Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
CONTENTS (Part -A of NSC-22 Proceedings) Preface Plenary Paper 1. Hundred years liquid helium 1 — A.T.A.M. de Waele 2. Cryogenics in launch vehicles and satellites 11 — Dathan M.C, Murthy M.B.N and Raghuram T.S 3. Nano-Kelvins in the laboratory 18 — Unnikrishnan. C. S. Cryo Component Development & Analysis 4. Development of plate and fin heat exchangers 27 — Mukesh Goyal, Rajendran Menon, Trilok Singh 5. Helium Liquefaction/Refrigeration System Based on Claude Cycle: A Parametric Study 33 — Rijo Jacob Thomas, Sanjay Basak, Parthasarathi Ghosh and Kanchan Chowdhury 6. Computation of liquid helium two phase flow in horizontal and vertical transfer lines 39 — Tejas Rane, Anindya Chakravarty, R K Singh and Trilok Singh 7. Experience in design and operation of a cryogenics system for argon cover gas 45 purification in LMFBRs — B.Muralidharan, M.G.Hemanath, K.Swaminathan, C.R.Venkatasubramani, A.Ashok kumar, Vivek Nema and K.K.Rajan 8. Design and implementation of an adiabatic demagnetization set up on a dilution refrigerator 51 to reach temperatures below 100mK — L. S. Sharath Chandra, Deepti Jain, Swati Pandya, P. N. Vishwakarma and V. Ganesan 9. Thermal design of recuperator heat exchangers for helium recondensation 57 systems using hybrid cryocoolers — G.Jagadish, G.S.V.L.Narasimham, Subhash Jacob 10. Experimental investigation on performance of aluminum tape and multilayer insulation 65 between 80 K and 4.2 K — Anup Choudhury, R S Meena, M Kumar, J Polinski, Maciej Chorowski and T S Datta 11. Finite element analysis of a spiral flexure bearing for miniature linear compressor 71 — Gawali B. S and Khot M. M. 12. Assessment of thermal radiation load on cryopanel of refrigerator based cryopump 77 — S G Gilankar and P K Kush Cryogenics for Space, Accelerator & Tokamak 13. On-orbit performance of Kalpana-1 VHRR radiant cooler 83 — B.S. Akkimaradi, Madhu Prasad, Santa Ram, Subramanya, A. K. Shrivastava, D. W. Tijare, S.C. Rastogi* and D. R. Bhandari 14. Commissioning of superconducting linear accelerator at IUAC 89 — R.Mehta, S.Ghosh, G.K.Chowdhury, A.Rai, P.Patra, B.K.Sahu, A.Pandey, D.S.Mathuria, J.Chacko, A.Chowdhury, S.Kar, S.Babu, M.Kumar, R.S.Meena, S.S.K.Sonti, K.K.Mistry, J. Zacharias, P.N.Prakash, T.S.Datta, A. Mandal, D.Kanjilal and A.Roy 15. Evolution of thermal shield for ITER torus & cryostat cryoline 95 — Badgujar S., Vaghela H., Shah N., Bhattacharya R. and Sarkar B. 16. Operating experience of cryogen distribution system for VECC K500 101 superconducting syclotron — Chinmay Nandi, Tamal Bhattacharyya, Tanmoy Das, Sanjay Bajirao, Santosh Mishra, Gautam Pal and Rakesh Kumar Bhandari 17. Cryo-Box for testing small components 107 — H.Anantha Krishna, N.K.Misra, M.S.Suresh 18. Superconducting electron cyclotron resonanceion source using gifford mcmahon cryo coolers 113 — G.Rodrigues, P.S.Lakshmy, P.Kumar, A.Mandal, D.Kanjilal, A.Roy 19. Performance prediction and test results of LOX tank pressurisation system of cryogenic 118 propulsion stage tested in ISRO facility — M. Xavier, P.P. Kailasanathan and Ashish K. Kartikeya Cryocooler 20. Performance investigation of pulse tube refrigerator using straight and stepped pulse tubes 124 — Lokanath Mohanta and M.D. Atrey 21. Analysis of irradiation problems in optical cryocooler 129 — Biju T. Kuzhiveli, Subhash Jacob 22. Theoretical analysis of sorption compressor for J–T cryocooler 135 — Rohit Mehta, S.L.Bapat and M.D.Atrey 23. Theoretical model for thermoacoustic devices 141 — S. Mehta, H. B. Naik, K. P. Desai, M.D.Atrey 24. Modeling of inertance tube based on RLC circuit analogy 147 — Sarkar M. and Atrey M. D. 25. Relationship between the composition of a four component nitrogen-hydrocarbon mixture 152 charged into the system and that in circulation during steady state operation of a J-T refrigerator — N. Lakshmi Narasimhan, S. Srinivasamurthy and G.Venkatarathnam 26. High frequency pulse tube refrigerator for 100 K 158 — C.V.Thaokar and M.D. Atrey 27. Comparison of stirling type pulse tube refrigerators by CFD simulations 164 Y. P. Banjare, R. K. Sahoo and S.K. Sarangi 28. Numerical analysis of performance and loss mechanisms of a two-stage pulse tube cryocooler 170 — S.Kasthurirengan, Upendra Behra, Rahul N. Sagar, K.V.Dinesh, N.K. Mohammed Sajid, K.A. Shafi 29. Characterisation of adsorption compressor used in a charcoal – nitrogen adsorption cryocooler 176 — Leena. R and M. Jose Prakash 30. Developmental studies on low mass cryocooler Developmental Studies on Low Mass Cryocooler 182 — Ramasamy, A., Padmanabhan and Gurudath, C.S. Cryogenic Instrumentation 31. Magnetocardiogram and magnetoencephalogram using a SQUID based system 187 — K.Gireesan, C.Parasakthi, S.Sengottuvel, L.S.Vaidhyanathan, R.Baskaran, M.P. Janawadkar and T.S.Radhakrishnan 32. Effect of tempering on the cryotreated intergral diaphragm pressure transducers 192 — Nadig D.S., Jacob S., Karunanithi R., Manjunatha. R, Patil. S & Subramanian D., Prasad M.V.N., Geetha Sen 33. Cryogenically multiplexed discrete array type liquid level sensor for calibration of 196
capacitance type cryo level sensors of LOX and LH2 systems of cryogenic upper stage — R.Karunanithi, Subhash Jacob, D.S. Nadig, D.Subramanian and M.V. Narasimha Prasad 34. A numerical model for prediction of effective thermal conductivity of perforated plates in 202 matrix heat exchangers — S. Sunil Kumar and T. K. Nandi Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
CONTENTS (Part -B of NSC-22 Proceedings)
Vol. 35 No. 1-4, 2010 Preface Plenary Paper 1. Development of the cryogenic systems for the superconducting cyclotron and operational 209 experiences at CECC — R.K. Bhandari (for the VECC team) 2. Cryogenic challenges in operating superconducting RF cavities in CW mode 219 — Shrikant Pattalwar 3. Recent developments in cryocooler technology at IIT Bombay 226 — Milind D. Atrey Cryo Component Development & Analysis 4. Development of tilting pad thrust bearings for cryogenic turboexpanders 235 — Anindya Chakravarty, Rajendran Menon, and Trilok Singh 5. Thermodynamic properties of helium: A comparative study on different equations of state 240 — Rijo Jacob Thomas, Sanjay Basak, Parthasarathi Ghosh and Kanchan Chowdhury 6. Experimental set up for the development of a room temperature bore cryogen free 246 superconducting magnet system — S. Kar, A.Choudhury, P. Konduru, R. Kumar, R.G.Sharma, & T.S.Datta 7. Coil design and development for 0.6 MJ SMES 252 — U. Bhunia, J. Pradhan, S. Bandyopadhyay, A. De, T. Bhattacharyya, U. S. Panda, A. Roy, A. DuttaGupta, S. K. Thakur, M. Das, S. Saha, and R.K. Bhandari 8. Performance analysis and experimental results of cryogenic reciprocating expansion engine 258 with helium gas — Rupul Ghosh, R S Doohan, R C Sharma and P K Kush 9. Design of vortex tube module for high purity LOX separation 263 — Upendra Behera, S. Jacob, P. J. Paul, S. Kasthurirengan, R. Karunanithi, K. Dinesh 10. Study on the performance of coiled heat exchanger for cryogenic application 269 — R.Satya Meher, S.Srinivasa Murthy and G.Venkatarathnam 11. Performance analysis of a moving coil, opposed piston linear compressor 274 — S. Jagan Mohan, S. L. Bapat, M. D. Atrey 12. Evaluation of key parameters involved in the design of a superconducting cable in conduit 280 conductor (CICC) — Soumen Kar, G. P. Vishnuvardhan, Sandeep Kumar Lakhera, K. V. Ekka, A. Venimadhav, N. K. Kishore and V. V. Rao Cryogenics for Space, Accelerator & Tokamak 13. Development of cryogen delivery system for VECC K500 superconducting cyclotron cryopanels 286 — Gautam Pal, Chinmay Nandi, Sanjay Bajirao, Santosh Mishra, Tanmoy Das, Tamal Bhattacharyya and Rakesh Kumar Bhandari 14. Integrated stress analysis for section of ITER torus & cryostat cryoline 292 — Vaghela H., Badgujar S., Shah N., Bhattacharya R. and Sarkar B. 15. Design of HYRA superconducting quadrupole magnet cryostat 298 — Anup Choudhury, Jacob Chacko, Soumen Kar, N Madhavan & T S Datta 16. The effect of stabilisation of sensing element on the performance of pressure transducer 304 in space applications — Geetha Sen, D.Subramanian, and M.V.N.Prasa d 17. Comparative study of two concepts for 80 K helium generation system 310 — Shah N., Bhattacharya R., Vaghela H., Badgujar S. and Sarkar B. 18. Thermal performance of 20 K helium cryotarget simulator for space environment simulation 316 of imager radiant cooler thermal balance testing — P. Govindan, D.P. Karnik, N.K. Mishra Madhu Prasad, Basavaraj S.Akkimaradi, Sant Ram, T. Selvan, Subramanya, A.K. Shrivastava, D.W. Tijare, S.C. Rastogi, K. Badarinarayana & D.R. Bhandari 19. Large-scale helium liquefier/refrigerator for fusion devices: A global review and Indian 321 perspective planning — Kanchan Chowdhury, Rijo Jacob Thomas, Parthasarathi Ghosh and B. Sarkar Cryocooler 20. Experimental investigations on 80 K stirling type coaxial pulse tube refrigerator 327 — Mridul Sarkar and M. D. Atrey 21. CFD Modeling of double inlet pulse tube refrigerator 333 — Ashwin T.R, Narasimham G.S.V.L, and Subhash Jacob 22. Performance investigations on single stage stirling type pulse tube refrigerator with inline 338 configuration — Tendolkar M. V., Narayankhedkar K. G., Atrey M. D. 23. Development of stirling miniature cryocooler 345 — Mohananand Jadhav and Trilok Singh 24. Performance of an auto refrigerant cascade refrigerator with a phase separator and operating 350 with nitrogen-hydrocarbon and argon-hydrocarbon mixtures — H. Gurudath Nayak, S. Srinivasa Murthy and G. Venkatarathnam 25. Phasor analysis of pulse tube refrigerator using cfd analysis and isothermal model 356 — Lokanath Mohanta and M.D. Atrey 26. Design guidelines for a thermoacoustic refrigerator 362 — Ram C. Dhuley and M.D. Atrey 27. Development of mixed refrigerant cascade refrigerator operating with nonflammable and 368 flammable refrigerant mixtures — K. Rajesh Reddy, S. Srinivasa Murthy and G.Venkatarathnam 28. Theoretical analysis of pulse tube cryocooler using gas mixture as working fluid 373 — P.P.Patunkar and M.D.Atrey 29. Effect of regenerator material compositions on the performances of a two-stage pulse tube 379 cryocooler — S. Kasthurirengan, Upendra Behera, Rahul N. Sagar, K.V.Dinesh, K. A. Shafi 30. Miniature hybrid regenerator for cryocoolers 385 — Kiran Kumar Reddy Kotla and Biju T. Kuzhiveli Cryogenic Instrumentation 31. Design of a cryogenic amplifier using GaAs MESFET 391 — Koushik. R and Arindam Ghosh 32. Temperature sensor bonding and thermalization for measurement of temperature during 395 proto-type cryoline test of ITER — Bhattacharya R., Sonara D., Vaghela H., Shah N., Badgujar S. and Sarkar B. 32. Breakthrough studies of activated carbon and oxysieve for helium purification at 77K 400 — Nisith K. Das, Pradeep Kumar, Amitava Sur, Rakesh K. Bhandari 34. Palladium doped tin oxide based hydrogen gas sensors for safety applications 405 — S.Kasthurirengan, Upendra Behera, D.S.Nadig, Mahesh.G.Magadum, N.Narendrababu, G.B.Sanmathi 35. Temperature measurement using fiber bragg grating sensors for superconducting magnets 411 — R. Rajini-Kumar, K.G. Narayankhedkar, M. Süßer, G. Krieg, M D Atrey 36. Analysis of heat transfer modes through multilayer insulation (MLI) in the ranges 300 – 77 K 418 and 77 – 4.2 K — A. Senthil Kumar, M. V. Krishna Murthy, Subhash Jacob and S. Kasthurirengan 37. Design of LOX/LH2 cooled hydrostatic journal bearings for cryogenic rocket engine turbopumps 424 — K.D. Choukekar, T.K. Nandi, Paul P. George and M. S. Suresh Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Hundred years liquid helium
A.T.A.M. de Waele
Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
This paper is a historical overview of the field of low-temperature physics since the liquefaction of helium by Kamerlingh Onnes in 1908. First the performance of the first helium liquefactor is analyzed using the Ts-diagram of 4He. Next a bird’s-eye overview will be given of the developments that followed: the discoveries of superconductivity, of superfluidity of 4He and 3He, Bose-Einstein condensation in dilute atomic gases, and of improved of cooling technology such as with cryocoolers, dilution refrigerators, and nuclear demagnetization. Alternative ways of cooling, such as the vortex cooler, thermoacoustic refrigeration, and the cooling of vibrating mechanical objects, are new techniques with high potential.
Key words: history, superconductivity, superfluidity, cryocooling
INTRODUCTION The first liquefaction of helium has been One hundred years ago Kamerlingh Onnes the topic of several books and publications. liquefied helium for the first time[1]. In some The most recent one is the book by D. van way this was the end of an era but, on the Delft[2]. Yet it still is interesting to read the other hand it marks the starting point of a new original report by KO[1]. It is written in a lively one: it is the starting point of the field of low- style that is unusual nowadays as it pays temperature physics as we know it now. This attention to such things as the time of the paper is a personal view on the highlights in events, the visitors walking by, hiccups in the the past and describes some promising new experiments, etc. The setup is given in Fig.1. developments. Here and there the work of the Blue is air, green is hydrogen, orange is Low-Temperature group of the Eindhoven helium, and pink is (warm) alcohol. The lighter University of Technology will be placed in the colors are gas; the darker colors high- historical context. But first the original pressure gas or liquid. There are four dewars liquefactor of Kamerlingh Onnes (KO) will be for liquid air and three for hydrogen. However, treated in terms of the Ts-diagram of helium the hydrogen container above the helium as we know it now. This will clarify some of cryostat is pumped to a pressure of 6 cm of the difficulties KO had on the tenth of July, mercury so that the temperature is about 15 1908. K, just above the triple point of hydrogen. There are two throttling valves: one for hydrogen and one for helium. JULY 10, 1908 Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Cryogenics in Launch Vehicles and Satellites
Cryogenics in launch vehicles and satellites Dathan M.C1, Murthy M.B.N1 and Raghuram T.S2
Dathan M.C1, Murthy M.B.N1 and Raghuram T.S2 1Satish Dhawan Space Centre SHAR and 2 1Satish Dhawan SpaceLSSF/ Centre SDSC SHAR SHAR and 2LSSF/ SDSC SHAR
Indian Space Research Organisation is in the forefront of developing cost effective launch vehicles and satellites for the developing technological needs of India. The ever- increasing quest for high performance Launch Vehicles resulted in choosing higher specific impulse generating propellant combination of fuel and oxidizer. Towards meeting this objective, development and establishment of Cryogenic propulsion systems and launch facilities are under taken in the past decade. Also the future missions of ISRO like GSLV-MK3 as well as missions which are being planned for human in space targets the extensive use of Cryo propellants. This paper outlines the applications of cryogenics in brief and rocket technology in particular the historical evolution of Cryo propellant based rocket stages in the world, the criteria for selection of propellants and its associated problems, related developments in Indian Space Program, establishment of propellant filling facilities at Satish Dhawan Space Centre for current and future GSLV missions and the criticalities associated with filling activities at Launch Complex during chronological operations before Vehicle Lift-Off.
Key words: Launch Vehicle, propellant, thrust, specific impulse, hydrogen and oxygen
INTRODUCTION cryogenic propellants like liquid hydrogen and liquid oxygen are to be used. Indian Space Research Organisation (ISRO) Towards meeting this objective is in the forefront of developing cost effective development and establishment of Cryogenic launch vehicles and satellites for the propulsion systems and launch facilities are developing technological needs of India. In its under taken in the past decade. The Geo- endeavor to provide high performance and Synchronous Satellite Launch Vehicle reliable launch systems, ISRO since its (GSLV), which has been successfully inception has been in search of various launched four times is configured with propulsion technologies. The process started Cryogenic propulsion using LH2 and LOX as with solid propulsion systems in 1970’s and propellants for its third stage. The achieved migrated to liquid propulsion systems in specific impulse of the cryostage in all the 1980’s. However, to launch heavy INSAT flights is of the order of 450-460s, which class communication satellites in Geo- corresponds with similar cryo stages launched Stationary Orbit and for future interplanetary in the world. missions it is mandatory that higher performance propulsion systems utilising For servicing the Cryostage propellant storage and transfer facilities comprising of 18 Nano-Kelvins in the laboratory
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Nano-Kelvins in the Laboratory
Nano-Kelvins in the laboratory Unnikrishnan. C. S.
Unnikrishnan. C. S. Gravitation Group, TIFR, Homi Bhabha Road, Mumbai 400005 Gravitation Group, TIFR, Homi Bhabha Road, Mumbai 400005
The quest for getting closer to the absolute zero temperature is driven by the ever-rich physics treasures that are hidden in the fragile and thin layers of temperatures near absolute zero. The application potentials of these discoveries so far have been spectacular. Gaseous samples containing millions of atoms can be cooled to a few nano- Kelvin temperature by a combination of laser cooling techniques, magnetic or optical trapping, and evaporative cooling. Important quantum phase transitions that are sensitive to the spin of the fundamental particles, like Bose-Einstein Condensation, happen in the region between 1 micro-K and 100 nano-K. Applications of some of these developments are in high precision measurements, ultra-stable atomic clocks, inertial sensing, gravimetry etc. This paper discusses the various principles and techniques involved in cooling gaseous atomic samples down to 100 nano-Klevin or lower, starting from room temperature, maintaining their vapor state. Some recent advances in the use of the familiar adiabatic demagnetization at the atomic scale in vapor state in this context are mentioned. A selected assortment of important applications that became possible due to these developments is briefly introduced.
Key words: Laser Cooling, Absolute Zero, Evaporative Cooling, Ultra-cold atoms, Bose- Einstein Condensation, Fermions, Demagnetization cooling.
INTRODUCTION between temperature and mean molecular kinetic energy. Indeed, it is the possibility to Temperature is one of the most direct physical change the temperature of all kinds of quantities that are not only sensible and materials and then study their properties that measurable by a variety of means, but also helped in the development of modern tunable over a wide range. Every complex microscopic physics of the solid state. There system in this universe, physical, chemical, are several motivating factors behind the and biological, responds to temperature desire to cool macroscopic samples below a changes in drastic ways, and in physical micro-Kelvin temperature. Control of transport systems the most spectacular of these properties like electrical conductivity, study of changes are phase transitions. While heating novel phase transition and ordering, a system to reach high temperature is very especially those related to magnetism, interesting for both applications and for observation and study of nonthermal quantum observing and studying interesting phase transitions, reduction of thermal noise phenomena, cooling physical systems occupy to reveal quantum fluctuations and their study a very special position in physics and etc. are some of these. Low temperature in a technology due to the microscopic link gas or vapor phase has a special significance Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Development of plate and fin heat exchangers
Development of plate and fin heat exchangers Mukesh Goyal, Rajendran Menon, Trilok Singh Mukesh Goyal, Rajendran Menon, Trilok Singh Cryo Technology Division, Bhabha Atomic Research Centre, Mumbai Cryo Technology Division, Bhabha Atomic Research Centre, Mumbai
This paper presents development of compact plate and fin heat exchangers with offset- strip fins carried out for use in helium liquefaction/ refrigeration systems. Various empirical correlations [1, 2, 3] available in the literature for dimensionless heat transfer and pressure drop characteristics have been reviewed. Design optimization and sizing calculations based on these empirical correlations taking into account axial heat conduction [4], temperature dependant fluid and material properties have been presented. Based on our design heat exchangers were fabricated. Testing for mechanical strength and leak- tightness was done. Destructive examination was done to see the quality of core brazing and distribution of fins inside the core. Thermal performance evaluation tests were carried out. Test results have been analysed and presented in this paper.
Key words: Offset strip fins, compact plate and fin heat exchangers, heat exchanger design, cryogenic system.
INTRODUCTION material properties can noticeably affect heat exchanger sizing [6]. Heat exchangers are one of the critical Plate and fin type of heat exchangers components of cryogenic process systems. which are commonly used in helium Cryogenic heat exchangers need high liquefaction/ refrigeration systems were effectiveness and high degree of developed for laboratory scale helium compactness. Practical helium refrigeration/ liquefaction system (Fig. 1).
C h a rco a l C h a rco a l liquefaction systems need heat exchanger A d so rb e r A d so rb e r E xp a n sio n E xp a n sio n T u rb in e -1 T u rb in e -2 P ro ce ss effectiveness of 0.95 or above. High degree of m e1 m e 2 compactness is required to accommodate a C o m p re sso r m f 1 2 8 large amount of surface area in a small volume 3 4 5 6 7 m - m f thus reducing heat in-leak from the 1 5 1 4 13 1 2 1 1 2 1 atmosphere. It also reduces thermal inertia of 1 5 9 JT va lve heat exchanger, which in turn, helps in faster g 10 3 L iq u e fie r cool down. 4 f m f 1 4 T 5 6 Longitudinal heat conduction can 7 1 3 8 1 2 seriously reduce the effectiveness of heat 9 11 f g exchangers with short flow length designed for 1 0 high effectiveness (� > 0.9) [5]. In few s cryogenic applications (like below 15K for Figure 1. Helium liquefier process schematic Helium) effect of temperature dependant fluid, with T-S diagram Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
HeliumHelium Liquefaction/Refrigeration liquefaction/refrigeration systemSystem basedBased on on claude Claude cycle: Cycle: A Parametricparametric studyStudy
Rijo Jacob Thomas, Sanjay Basak, Parthasarathi Ghosh and Kanchan Chowdhury
Cryogenic Engg. Centre, Indian Institute of Technology, Kharagpur, 721302, India.
Large-scale helium liquefaction/refrigeration systems are based on modified Claude cycleLarge-scale and its variations. helium These liquefaction/refrigeration systems are constituted syste ofms various are basedcomponents on modified including Claudecompressors, cycle and purification its variations. systems, These an array systems of heat are exchangers, constituted turbo-expanders, of various components etc. The includingperformance compressors, of these systems purification is dependent systems, on an the arr geometricay of heat and exchangers,operating parameters turbo- expanders,of each of etc.these The components. performance These of these parameters systems are is intricately dependent connected on the geometric with each andother, operatingand decide parameters the final output of each of ofthe these system. components. The combined These and parameters intertwined are action intricately of these connected with each other, and decide the final output of the system. The combined and process parameters makes the study of system behavior difficult. This necessitates the intertwined action of these process parameters makes the study of system behavior use of process simulators for understanding the steady state and dynamic behaviours of difficult. This necessitates the use of process simulators for understanding the steady statesuch and large-scale dynamic systems. behaviours As the of ground such large-scale work for designing systems. a large-scale As the ground helium work liquefier, for designinga parametric a large-scale study of a liquefaction helium liquefier, system a based paramet onric two-turboexpander study of a liquefaction Claude cycle system has basedbeen onundertaken. two-turboexpander Such a simple Claude cycle, cycle however, has been has all un thedertaken. basic characteristics Such a simple of cycle,a large- however,scale helium has all liquefier the basic and characteristics the results of the of studya large-scale can always helium be extrapolatedliquefier and to the large-scale results of systemsthe study effectively. can always be extrapolated to large-scale systems effectively.
Key words: Helium liquefaction, Parametric study, Cycle design, Multi-expander Claude cycle.
INTRODUCTION temperature [2]. While designing an highly energy intensive system like helium Helium liquefiers/ refrigerators are utilized in refrigeration/liquefaction system, therefore, contemporary large-scale installations like from the thermodynamic point of view, the Tokomaks, Particle Accelerators, Colliders, system parameters like component Synchrotrons, etc. Helium refrigeration/ efficiencies, stream pressures and flow rates, liquefaction systems are based on Claude temperature difference in heat exchangers, cycle, which is the combination of Linde and temperature levels of components etc have to Brayton cycles [1]. Large-scale helium be properly selected so that an optimum refrigerators/ liquefiers have multi-expander efficiency is achieved. But these parameters Claude cycle based configurations and thus are intricately connected with each other and involve many refrigeration stages to pre-cool their combined and intertwined action always the feed gas to below its inversion makes it difficult to understand the cycle temperature, before entering the throttle stage. behavior. Also some of these parameters will For cryogenic cycles, even when have to be traded off against others in order to considered reversible, expenditures of energy achieve an optimum efficiency. Thus, for the are substantial and increase with decrease in all round design optimization, an integrated Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Computation of liquid helium two phase flow in horizontal and vertical transfer lines Computation of liquid helium two phase flow in horizontal and vertical transfer lines Tejas Rane, Anindya Chakravarty, R K Singh and Trilok Singh
Tejas Rane, Anindya Chakravarty, R K Singh and Trilok Singh Bhabha Atomic Research Centre, Mumbai, India. Bhabha Atomic Research Centre, Mumbai, India.
In a liquid helium transfer line, heat transfer and pressure drop occurs along the length of the pipe resulting in boiling. The present work describes theoretical modeling and computation of two phase liquid helium flow in a pipe with pressure drop and heat transfer. Empirical correlations have been used for heat transfer coefficient and pressure drop. The transfer line has been modeled as a two dimensional, axisymmetric heat conduction problem, with a constant external heat flux (as a boundary condition) flowing into the pipe, through superinsulation. The heat transfer coefficient forms the other boundary condition. The pipe length is divided into small segments within which the fluid properties are assumed constant, however property variation along the length from segment to segment is considered. This model has been used to predict flow variables and their behavior for two-phase liquid helium flow.
Key words: two phase liquid helium flow, transfer line, empirical correlation.
INTRODUCTION flow. The solution method described in the paper is only confined to steady state flow in Optimization of heat in leak and pressure straight transfer lines with no other drop are the major considerations for design components such as valves, etc. in between. of transfer lines. Pressure drop in pipes is (Only a solid pipe has been modeled). sometimes not considered when other sources of pressure drop such as valves, DESCRIPTION OF PROBLEM bellows etc dominate. Generally heat transfer to cryo-lines is very low. Hence we assume a The definition of problem to be solved is linear variation of quantities such as pressure, shown schematically in figure1. vapour fraction. The heat transfer is also approximated to be one dimensional and Uniform heat flux through superinsulation radial. The aim of present work reported here is Liquid to solve the two phase liquid helium flow helium two phase flow problem in transfer lines, from a more holistic Pressure drop along angle, without making simplifying the length approximations as stated above and hence understand, behaviour of different variables, such as pressure, vapour fraction, during Figure 1. Problem definition Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Experience in design and operation of a cryogenics system for argon cover gas purification in LMFBRs Experience in design and operation of a cryogenics system for argon cover gas purification in LMFBRs B.Muralidharan1, M.G.Hemanath1, K.Swaminathan2, C.R.Venkatasubramani2, A.Ashok kumar1, 1 1 B.Muralidharan1, M.G.HemanathVivek Nema1, K.Swaminathan and K.K.Rajan2, C.R.Venkatasubramani2, A.Ashok kumar1, Vivek Nema1 and K.K.Rajan1 1Fast Reactor Technology Group, 2Chemistry Group 1Fast Reactor Technology Group, 2Chemistry Group Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 ([email protected]) Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 ([email protected])
The 500 MWe Prototype Fast Breeder Reactor (PFBR), is at an advanced stage of construction at Kalpakkam in India. In case of a breach of clad, the gaseous fission products – isotopes of krypton and xenon - are released to the argon cover gas. The simplest technique to remove these radioactive gases is by adsorption on activated charcoal. The process taking place is called Dynamic Adsorption and results in a time delay for the passage of the noble gases through the bed allowing the short lived radionuclides to decay. The Dynamic Adsorption Coefficient (DAC) increases substantially with decrease in temperature and at cryogenic temperatures, the residence time increases significantly for a given quantity of activated charcoal. To validate the design parameters used for the cover gas purification system in PFBR and to gain experience in operating a cryogenic system, it was decided to set up a pilot plant. This paper describes the design and operation of the pilot plant and the feedback from the same.
Key words : DAC, purification, adsorption, charcoal, cryogenic, CGPS, liquid nitrogen, cold box
INTRODUCTION is a commercial reactor designed to operate with up to four failed fuel pins (as gas leakers) Nuclear fission results in the break up of the in the core. Due to breach of clad, the argon fissile nucleus into two more or less equal cover gas over the sodium pool would be pieces. This process is highly exoergic and contaminated with fission gases. the heat liberated is converted to electric Computations have shown that even if this power in nuclear reactors. The fission gas is released without any treatment, the products formed in this process are highly dose at the site boundary would be well below radioactive and transform to stable nuclei by permissible limits. However, in accordance successive beta decay. The radioactive with the principle of ALARA (as low as fission products are contained inside the fuel reasonably achievable) and to ensure pin by the clad. In the case of a breach of minimum release (thus permitting more clad, the gaseous fission products – isotopes number of reactors in one site), it was of krypton and xenon – would be released decided to treat the cover gas to remove the from the fuel to the primary heat transport radioactive fission gases. The method chosen medium and thence to the cover gas. was adsorption on activated charcoal at The Prototype Fast Breeder Reactor (PFBR) cryogenic temperatures[1]; a method that has Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Design and implementation of an adiabatic demagnetization set up on a dilution Design and Implementationrefrigerator toof reachan Adiabatic temperatures Demagneti belowzation 100m setK up on a Dilution Refrigerator to Reach Temperatures below 100mK L. S. Sharath Chandra, Deepti Jain, Swati Pandya, P. N. Vishwakarma and V. Ganesan L. S. Sharath Chandra, Deepti Jain, Swati Pandya, P. N. Vishwakarma and V. Ganesan UGC-DAEUGC-DAE Consortium Consortium for for Scientific Scientific Research,Research, UniversityUniversity Campus, KhandwaKhandwa Road, Road, Indore Indore – – 452 452 001 001
The design and implementation of an adiabatic demagnetization cell using Cerium- Magnesium-Nitrate salt to work with an existing 100mK dilution refrigerator are presented. The salt crystals were grown by slow evaporation technique. Salt and Glycerin are mixed to make slurry and filled inside a copper can. Copper wires are used as thermal link between the salt and the can. Graphite rod was the thermal isolator below 1K. The measurement leads are the weak links between mixing chamber and the cell. The salt was magnetized and allowed to reach thermal equilibrium at ~150mK and then stepwise demagnetization trials were carried out to reach temperatures as low as 69mK.
INTRODUCTION where R is the universal gas constant. The spins are completely disordered in possible Adiabatic Demagnetization of a paramagnetic 2J+1 orientation with respect to a magnetic salt is the first tool that was discovered to reach field. This magnetic disorder entropy will be temperatures below 0.3K [1-4]. This technique utilized in refrigeration. For a spin half system, was independently proposed by Debye and below 1K, this magnetic entropy is about Giauque, during 1926-27. It was first put 5.76J/molK, which is very large compared to all forwarded for practical realization by Giauque other entropies like lattice and conduction and MacDougall, and little later by De Haas, electron entropies of the system. If the Wiersma and Kramers in 1933. Even though temperature is decreased, the interactions this method is mostly obsolete due to the between the magnetic moments will become advent of Dilution Refrigerator, it is the only comparable to the thermal energy. This will lead principle still available to reach sub mK to magnetic ordering such as ferromagnetism or temperatures through Nuclear Demagnetization antiferromagnetism, which makes the entropy [1-4]. zero. Hence, in presence of magnetic field entropy will decrease at much higher For paramagnetic ions in a solid with temperatures than that at zero magnetic field electronic magnetic moment µ and total angular [1-4]. In Figure 1., (reconstructed from ref. 1) momentum J, the magnetic entropy S is given the entropy of a popular paramagnetic salt by CMN salt is presented at various magnetic fields. S = R ln(2J+1) In our laboratory, we have a working dilution refrigerator with a base temperature of about Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Thermal design of recuperator heat exchangers for helium recondensation Thermal design of Recuperator heat exchangers for Helium Recondensation systems using hybrid cryocoolers systems using Hybrid Cryocoolers G.Jagadish1, G.S.V.L.Narasimham2, Subhash Jacob1 G.Jagadish1, G.S.V.L.Narasimham2, Subhash Jacob1 1Centre1Centre for for Cryogenic Cryogenic Technology, Technology, 2Department 2Department of Mechanical of Mechanical Engineering Engineering IndianIndian InstituteInstitute ofof Science,Science, Bangalore-560012, Bangalore-560012, India India
This paper reports the thermal design of heat exchangers for a pulse-tube refrigerator based helium recondensation system consisting of recuperators and regenerators of a two-stage pulse tube cooler. The constraints on the thermal design of the heat exchangers are the need for high effectiveness and lower pressure drop. A detailed study is carried out to choose the best recuperator heat exchangers out of Giauque-Hampson, Perforated plate and the Collins heat exchanger configurations, based on the design considerations in terms of temperature and pressure. The pressure drop should be commensurate with the optimal pressure ratio of the linear motor compressor. During the calculations, due consideration is given to the geometrical parameters and practical constraints for manufacturing, apart from performance and pressure drop. To this end, suitable computer programs have been developed. Results are presented in the form of graphs for pressure drop on the hot and cold sides and the effectiveness for varying physical dimensions of the recuperator heat exchangers.
Keywords: Heat exchangers, Collins heat exchanger, Giauque heat exchanger, Perforated plate heat exchanger
INTRODUCTION has shown in his analysis that decreasing the heat exchanger effectiveness from 97% to An important problem in developing helium 95% reduces the liquefaction yield in a helium refrigeration units is the selection of heat liquefier by 12%. This necessitates thorough exchangers. These should be reliable; the understanding of different loss contributing methodology of their fabrication should mechanisms that affect the performance of facilitate easier manufacturing and should be heat exchanger to arrive at optimum highly efficient. geometrical configurations. In the present Different heat exchangers like Collins heat work, relevant correlations for pressure drop, exchanger, perforated plate heat exchangers friction factor and other expressions related to and Giauque-Hampson heat exchanger are geometrical parameters are taken from the used in cryogenic refrigerators/liquefiers. The available literature and an attempt has been design of these cryogenic heat exchangers is made to develop computer codes for the always aimed at achieving limited pressure design of heat exchangers. Using these drops and high effectiveness. In fact, a codes, optimal configurations for better cryogenic liquefier will produce no liquid if the thermal and pressure drop performance have heat exchanger effectiveness is less than been arrived at for the operating parameters of approximately 85% in contrast to a the helium recondensation system shown in conventional heat exchanger used in other Figure 1. The geometry of recuperator heat systems with lesser effectiveness [1]. Atrey [2] exchangers (HX-1, HX-3 and HX-5) has been Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Experimental Investigation on Performance of Aluminum Tape and Multilayer Insulation Between 80 K and 4.2 K Experimental investigation on performance of aluminum tape and multilayer insulation between 80 K and 4.2 K Anup Choudhury1 , R S Meena1, M Kumar1, J Polinski2, , Maciej Chorowski2 and T S Datta1 Anup Choudhury1 , R S Meena1, M Kumar1, J Polinski2, , Maciej Chorowski2 and T S Datta1
1.Inter1Inter University Accelerator Centre (IUAC), Aruna AsafAsaf AliAli Road,Road, NewNew Delhi-110067Delhi-110067 2. Wroclaw University of Technology, Wroclaw, Poland 2Wroclaw University of Technology, Wroclaw, Poland [email protected] [email protected]
Complexity of fabrication, limited available space for insulation, requirement of clean environment around cavity for the development of cryomodules and cryo lines related to Superconducting linear accelerator at IUAC, necessitated to explore alternate cryogenic insulation between 80 K and 4.2 K. Thermal performance study of single layer adhesive aluminum tape between 80 and 4.2 K is carried out by an indigenously developed SS calorimeter. Comparison of performance with multi layer insulation at various level of vacuum is also reported here. This paper will present the experimental procedure and results on heat transfer rate for combination of different parameters.
Keywords : MLI, Aluminum tape, Calorimeter, Heat transfer
INTRODUCTION
A superconducting linear accelerator as a liquid nitrogen shielded, mutilayer insulated ii) booster of existing 14 UD pelletron is under liquid nitrogen shielded with one layer development at Inter University Accelerator adhesive aluminum tape iii) Only MLI Center Delhi. Acceleration is achieved by insulated, standard safe option (i) was chosen using quarter wave niobium cavities at 4.2 K, in spite of complex nature of fabrication work. and these cavities are housed in 5 beam line The measured total head load for 50 meters cryostats. Beam line cryostats are integrated length with four valve boxes comes about 40- with helium/nitrogen refrigerator through 50 W and major load contribution comes from indigenously developed liquid helium/ valves, instrument penetration, vacuum break nitrogen distribution line with valve boxes. (At and field joint. Multilayer insulation (MLI) is an present approx. 50 meters length with four efficient, well-proven and widely implemented valve boxes are developed and is being used technique [1] for reducing heat flux from for last 8 years for of line and on line tests of ambient to cryogenic temperature. The case partly established LINAC). The liquid helium is not clear for insulation below 80 K. As transfer line is liquid nitrogen shielded, radiation is significantly reduced below 80 K, multilayer insulated and enclosed in a multilayer option may not be economical. vacuum jacketed pipe of 8 inches diameter. Although significant reports are available on The cross section of IUAC distribution line is performance of widely used MLI but mostly presented in Fig 1. Out of various design restricts between 300-80 K [2,3,4] and few configuration options like i) Vacuum jacketed, are between 80-4.2 K [5,6,7,8]. For the Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Finite element analysis of a spiral flexure bearing for miniature linear compressor
GawaliGawali B. B. S S.,and Khot Khot M. M. M. M.
Department of Mechanical Engineering, Walchand College of Engineering, Sangli, Maharashtra.
Spiral flexure bearings are used in miniature cryocoolers to support the compressor motor assembly and displacer. Research has been carried out to present the methodology for the analysis of spiral flexure bearing. The parametric analysis is performed to study the influence of spiral swept angle on strain, stress and axial stiffness. Finite Element Analysis (FEA) has been used to determine the von mises strain characteristics and axial stiffness characteristics for different spiral swept angles using commercial code ANSYS 10. Some of the FEA model results are validated with experimental results.
Key words: spiral flexure bearing, finite element method, flexure thickness and spiral swept angles, strain and axial stiffness measurement.
INTRODUCTION the radial forces and lubrication problem. Figure 1 shows the schematic of linear The satellite based electronic sensors, infra- compressor in which the piston is supported red detectors system, thermal imaging by two stacks of bearings. The bearing cameras, SQUIDS and vast variety of circuits requirement of these compressors is achieved requires cryogenic cooling. Such type of with the help of a non conventional applications demand very high reliability, low suspension system called flexural suspension specific power consumption, a long or flexural bearing. Typical geometries of maintenance free life, small size, low weight these flexures are shown in Figure 2(a) and and low vibration levels. Miniature cryocoolers Figure 2(b). These bearings have increased are suitably used for these applications. Now the reliability and life of cryocoolers. The first a days linear compressors are commonly cryocooler using flexure bearings was used in miniature cryocoolers instead of rotary reported by the research group at the Oxford compressors because rotary compressors University in 1980s [1]. The problem of apply large radial forces on piston, which vibration is minimized by using a balanced- provide no useful work, cause large amount of opposed design. In this configuration, the wear, and usually require lubrication. As 0 pistons are counter balanced in line, 180 out miniature cryocoolers operate with of phase as shown in Figure 1. These regenerator, lubrication is a common problem compressors are driven by linear motors in these cryocoolers which contaminate the which can eliminate radial forces completely regenerators. Linear compressors eliminate Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009 `
Assessment of thermal radiation load on cryopanel of refrigerator based cryopump
S G Gilankar and P K Kush
Cryogenic Section, Raja Rammana Centre for Advanced Technology, Indore-452013
The cool-down time for a refrigerator cryopump is one of the important performance parameter as it determines total operation cycle, pumping speed, maximum pumping throughput and other parameters. A closed cycle refrigerator based cryopump for 1000 lit/s pumping speed for nitrogen was developed earlier using small indigenous two stage GM-cryocooler. Performance of this cryopump was evaluated over a long period by carrying out exhaustive tests in order to establish its cool-down time, ultimate pressure, pumping speed, cross-over rating, maximum throughput, and gas capacity. Thermal radiation load is a major heat load on cryopanel affecting the cool down time of cryopump, particularly in case of first stage radiation shield. In this paper, cool down time of cryopump with blank–off flange is approximately estimated and compared with experimental cool down performance. Thermal radiation load on cryopanels was assessed from experimental data of ideal cool down performance of cryopump with blank-off flange and the same is compared with theoretically estimated values. Variation of specific heat with temperature for copper was considered for cool down estimation.
Key words: Cool down time, Thermal radiation, Refrigeration capacity, Cryopump
INTRODUCTION helpful in estimating cool down time of designed cryopanels of cryopump or vice- The cool down time to reach 20 K is one versa. The cool down time for a given mass of of the critical parameter of closed cycle cryopanel is dependent on net refrigeration refrigerator based cryopump as it affects capacity of refrigerator. Thermal radiation operation cycle, pumping speed, maximum heat exchange between the panels and warm pumping throughput of the pump [1]. But cool surfaces of cryopump housing determines net down time is mainly influenced by thermal refrigeration power available for cool down. A radiation load on panel and mass of closed cycle refrigerator based cryopump of cryopanel. The cool down time to reach 20 K 1000 lit/s pumping speed for nitrogen was for second stage cold panel and 80 K for first developed earlier using small indigenous two stage radiation shield of cryopump can be stage GM-cryorefrigerator in cryogenic roughly estimated [1]. For a given two stage section of RRCAT [2]. In this paper, the cool refrigerator and shape of panel, assessment down for cylindrical cryopanels of this pump is of the expected radiation load on panel is analyzed. Variation of specific heat of copper Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
On-OrbitOn-orbit Performance performance ofof Kalpana-1Kalpana-1 VHRRVHRR Radiantradiant coolerCooler
B.S. Akkimaradi, Madhu Prasad, Santa Ram, Subramanya, A. K. Shrivastava, D. W. Tijare, S.C. Rastogi* and D. R. Bhandari
Thermal Systems Group, ISRO Satellite Centre, Bangalore 560 017
Three-stage passive radiant cooler has been designed and successfully realized in the KALPANA-1 spacecraft that was put into orbit on September 12, 2002 using the Polar Satellite Launch Vehicle (PSLV-C4). The radiant cooler maintains the detectors of the VHRR at cryogenic temperature (100–110 K) for optimum performance. The flight performance of the radiant cooler has been very much up to satisfaction. Now it has successfully completed six years in orbit. Initially cooler was maintained at nearly 300 K for one week to avoid contamination of thermo-optical surfaces. On-obit data for seasons like equinox (September, March), winter (December) and summer (June) of all the years in orbit are presented. Performance of the cooler over the years is depicted and prediction is done for end of life condition.
Key words: radiant cooling, cryogenic cooling, on-orbit performance
INTRODUCTION KALPANA-1 (Figure 1) is the first dedicated Indian Satellite for meteorological applications. Also, unlike earlier satellites, which carried radiant cooler, it is without solar sail and boom. It was launched on 12th September 2002 (10:23:43 UT) on PSLV-C4 from Satish Dhawan Space Centre. Radiant cooler for KALPANA-1 spacecraft developed at Thermal Systems Group of ISRO Satellite Centre, Bangalore, is a sub assembly for 3- channel Very High Resolution Radiometer (VHRR). VHRR is the meteorological payload on-board KALPANA-1 spacecraft. It takes Earth imagery in visible channel (0.55 to 0.75 m band), Water Vapour channel (WV) in 5.7 to 7.1 m band and Thermal Infra Red (TIR) channel in 10.5 to 12.5 m band. TIR and WV, Mercury Cadmium Telluride (HgCdTe) Figure 1. KALPANA-1 Spacecraft detectors need to b0.e maintained at cryogenic temperature. The radiant cooler Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Commissioning of Superconducting Linear Accelerator at IUAC Commissioning of superconducting linear accelerator at IUAC
R.Mehta, S.Ghosh, G.K.Chowdhury, A.Rai, P.Patra, B.K.Sahu, A.Pandey, D.S.Mathuria, J.Chacko, R.Mehta,A.Chowdhury, S.Ghosh, S.Kar, G.K.Chowdhury, S.Babu, M.Kumar, A.Rai, P.Patra, R.S.Meena, B.K.Sahu, S.S.K.Sonti, A.Pandey, K.K.Mistry, D.S.Mathuria, J. Zacharias, J.Chacko, A.Chowdhury, S.Kar,P.N.Prakash, S.Babu, M.Kumar,T.S.Datta, R.S.Meena,A. Mandal, D.KanjilalS.S.K.Sonti, and K.K.Mistry, A.Roy J. Zacharias, P.N.Prakash, T.S.Datta, A. Mandal, D.Kanjilal and A.Roy Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi – 110067 Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi – 110067
First module of niobium (Nb) based Superconducting Linear Accelerator (LINAC) has been commissioned to augment the energy of the ion beam from the Pelletron of Inter University Accelerator Centre (IUAC). Full accelerator will consist of three LINAC modules, one superbuncher cryostat and one rebuncher cryostat. At present one LINAC module along with superbuncher and rebuncher cryostat is operational. This paper deals with basics of rf superconductivity, various surface preparation techniques to improve the cavity performance and acceleration of beam through the first LINAC module.
Key words: Superconductivity, RF, Cavity, Surface Treatment, LINAC
INTRODUCTION high CW voltage grows with particle energy. Here superconductivity brings immense Superconducting RF (SRF) cavities excel in benefits. The surface resistance of a applications requiring continuous wave (CW) superconducting cavity is many orders of or long-pulse accelerating fields above a few magnitude less than that of a copper cavity. million volts per meter (MV/m). The There are also practical limits to dissipating accelerating device is an electromagnetic high power in the walls of a copper cavity. cavity resonating at a microwave frequency The surface temperature becomes excessive, between 50 and 3000 MHz. There are two causing vacuum degradation, stresses and distinct types of cavities, depending on the metal fatigue due to thermal expansion. Other velocity of the particles. The first category is important advantage that SRF cavities bring for accelerating charged particles that move to accelerators is their capability to provide at nearly the speed of light, such as electrons higher voltage, hence SRF systems can be in a high-energy linear accelerator or in an shorter. electron storage ring. The second type of cavity is for particles that move at a small fraction (e.g. 0.01–0.3) of the speed of light QUARTER WAVE CAVITY RESONATOR such as the heavy ions emerging from a dc high voltage Van de Graaff accelerator, or The Pelletron accelerator at IUAC is capable from an electron cyclotron resonance ion of accelerating ions having mass up to 40 source. Since the ohmic power loss in the amu above Coulomb barrier. To augment the walls of a cavity increases as the square of beam energy above Coulomb barrier for mass the accelerating voltage, copper cavities up to 100 amu, a booster superconducting become uneconomical when the demand for LINAC is being installed [1] (Figure 1). The Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Evolution of thermal shield for ITER torus & cryostat cryoline
Badgujar S., Vaghela H., Shah N., Bhattacharya R. and Sarkar B.
ITER-India, Institute for Plasma Research, Bhat, Gandhinagar – 382428, India
The design, engineering and analysis of the torus and cryostat (T & C) cryoline of International Thermonuclear Experimental Reactor (ITER) cryogenic system, have been done to satisfy the functional requirements. It has been understood from the design that the performance of the cryoline greatly depends on the performance of thermal shield and it has a great influence in achieving the target of minimizing overall heat load for the cryoline. During the design evolution of T & C cryoline, various options of thermal shield have been considered. The design options considered are of varied thickness and configuration with fixed and demountable assembly. The thermal analysis has been carried out using ANSYS© Simulation 10.0 for the thermal equilibrium. Aluminum as material of construction (MOC) with 3 mm thickness has been considered for the design of cryoline. The paper presents the design, configuration, analysis, optimization and prototype test concept of the thermal shield for the T & C cryoline.
Key words: ITER, T & C cryoline, Thermal shield, Finite element analysis
INTRODUCTION
The T & C cryoline is an ensemble of six process pipes, thermal shield (TS), fixed and sliding supports as well as outer vacuum jacket. It consists of straight, T, curved and elbow sections [1]. Figure 1 (a) and (b) shows the layout and cross-section for main Cross-section line and branch line of T & C cryoline (C/s) of main respectively. The thermal shield is used in cryostats and cryolines to reduce the heat inflow. The thermal shield design of industrial grade cryolines greatly depends on the C/s branch line fabricability aspects, MOC and steady state thermalization i.e effective temperature transfer to the shield. Stainless steel (SS), copper and aluminum are generally used as MOC for the thermal shield. It is understood Figure 1(a). Layout of T & C cryoline Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
OperatingOperating experienceexperience ofof Cryocryogengen distribution systemsystem forfor VECCVECC K500K500 Superconductingsuperconducting Cyclotronsyclotron
Chinmay Nandi, Tamal Bhattacharyya, Tanmoy Das, Sanjay Bajirao, Santosh Mishra, Gautam Pal and Rakesh Kumar Bhandari
Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata.
The VECC superconducting cyclotron is now undergoing commissioning test for beam trial. The 6.5 ton cold mass cyclotron magnet was first cooled down from room temperature to liquid helium temperature in a controlled manner during the year 2004. Detailed magnetic field mapping at different current was then carried out for almost 15 months. The magnet was cooled for the second time in March 2008. A dedicated control logic was developed to operate various controls, generate interlocks and communicate with the supervisory control of the cryogen distribution system for superconducting cyclotron magnet. The control parameters are operated through control loops operating independently on the dedicated PLC. Based on the earlier operating experience, some modifications in the hardware and control logic have been incorporated. During the operation and commissioning periods, many relevant parameters have been measured. The paper presents the improvements made, the operating experience and some observations related to cryogen distribution system.
Key words: Superconducting Cyclotron, Cryogenic system
INTRODUCTION cryogenic system for cryopanel was commissioned in February 2007 [2]. The A superconducting cyclotron for characteristics of VEC Cryogen distribution accelerating heavy ion is now in system, operating experience and observation commissioning stage at VECC Kolkata. The on various systems are reported in the main part of the cyclotron, the following sections. superconducting magnet was first cooled down from room temperature to liquid helium MODIFICATIONS IN CRYOGEN temperature during the year 2004 using DISTRIBUTION SYSTEM dedicated PLC controlled cryogen distribution system [1]. Magnet cryostat was filled with The cryogenic system of the liquid helium. Detailed magnetic field mapping superconducting cyclotron operates in a at different current combinations was carried closed loop. The detailed layout and the out for almost 15 months. The magnet was, control logic of the cryogen distribution system then, warmed up. Assembly of radio are described in [1], [2] and [3]. Construction frequency system, trim coils and cryogenic of cryogen distribution system was carried out system for cryopanel were then taken up. The in two phases. In the first phase, cryogen Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Cryo-Box for testing small components Cryo-Box for testing small components
H.Anantha Krishnaa, N.K.Misraa, M.S.Sureshb H.Anantha Krishnaa, N.K.Misraa, M.S.Sureshb aISROaISRO Satellite Satellite Centre Centre Bangalore; Bangalore; bBNM bBNM Institute Institute of ofTechnology, Technology, Bangalore. Bangalore.
Spacecrafts in Geostationary earth orbit and Low earth polar orbit experience temperatures in the range of -1800C to +800C[1][2] depending on the orbit. Environmental chambers and thermo vacuum chambers are used for tests (from small packages to a complete satellite) in temperature range -1500C to +1000C. The operation and maintenance of these chambers are very expensive and consume a lot of resources. As these chambers / facilities are huge, test setup needs to be relocated depending upon the availability of the chambers. A simple Cryo-box that use easily available components and materials is designed, built, tested and calibrated for operation in the temperature range of -1800C to +800C. The Cryo-box was specifically designed and developed for measuring the characteristics of a solar cell but it may be used for any other small component. A linear temperature sweep of 1.40C/min is achieved using this facility.
Key words: Cryo-box, Cryo-box component testing, Expanded Polystyrene (EPS).
INTRODUCTION dissipated as heat. The solar panels radiate heat into cold space (4K) and equilibrium is 0 0 Earth bound spacecrafts, both in near earth attained around 50 C to 80 C. During eclipse and geostationary orbits, use solar panels for Sun light is absent and the solar panels reach 0 generating the required power for its very low temperatures, up to -180 C. The operation. Solar cell is the basic building unit solar panel temperature varies during seasons in the solar panels, large numbers of which and over its life of 4 to 20 years. As the solar are bonded on a honeycomb panel, cell characteristics are a function of connected in series-parallel to generate power temperature it is essential to know the at the required voltage and current. The solar characteristics of solar cells over the operating 0 0 panels are illuminated during sunlit period temperature range (-180 C to +80 C). when it generates power needed by the The current voltage characteristics of satellite and is eclipsed from the Sun when solar cells and hence, the power generated, is the satellite goes behind the earth. Batteries highly dependent on temperature [3]. Typical supply power during eclipse, which are characteristics of silicon solar cells at different charged by solar panels during sunlit period. temperatures are shown in Figure1. When the solar panels are illuminated the It is observed that for a fixed illumination solar energy falling on it is about 1.35 kW/ m2 the solar cell voltage varies considerably with and only 12% to 25% of it is converted to temperature while its current is fairly constant. electrical energy, the remaining being Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
SUPERCONDUCTING ELECTRON CYCLOTRON RESONANCE ION SOURCE USING GIFFORD MCMAHON CRYO-COOLERS
G.Rodrigues,Superconducting P.S.Lakshmy, electron P.Kumar, cyclotron A.Mandal, resonanceion D.Kanjilal, A.Roy source using gifford mcmahon cryo coolers
G.Rodrigues,Inter University P.S.Lakshmy, Accelerator P.Kumar, Centre, A.Mandal, New Delhi D.Kanjilal, – 110067 A.Roy [email protected] Inter University Accelerator Centre, New Delhi–110067 [email protected]
As a part of the accelerator augmentation program at the Inter University Accelerator Centre, New Delhi, a high temperature superconducting (HTS) electron cyclotron resonance (ECR) ion source using single stage Gifford McMahon cryo-cooler has been developed and installed. It will be used as a high current injector device for injection of ion beams having a A/q (max) up to 7 for further acceleration into the superconducting linear accelerator. The novel feature of this ion source is the use of high temperature superconducting BSCCO wires instead of normal copper to minimize the power requirements from ~ 200 kW to ~ 20 kW for operating the source on a 400 kV high voltage platform. The high temperature superconducting coils are cooled using single stage Gifford McMahon cryo-cooler to ~ 20 K for optimum operation. The ion source is presently in continuous operation at ground potential and being utilized for various kinds of experiments. The source will be placed on a high voltage platform in order to prepare for injection into the superconducting linear accelerator. Some of the operational experiences of the Gifford McMahon cryo-coolers and its impact on the performance of the ion source will be presented and highlighted.
Key words: ECR ion source, cryo-coolers, high voltage platform
INTRODUCTION higher operating temperatures and makes the system more compact to construct. With the advancement of technology of Although the cost estimates are orders of Gifford McMahon cryo-coolers, most of the magnitude higher than those of LTS superconducting magnets have been materials, a one-time capital investment will designed using these cryo-coolers minimize the long term power requirement depending on the cooling requirements of for the system. At the Inter University the magnets. These cryo-coolers broadly fall Accelerator Centre, New Delhi, the into two categories; viz., single stage cooling accelerator augmentation programme [1] for magnets above 20 K or two-stage cooling demands the use of high current injectors for magnets which are designed for for a wide range of ions throughout the operation at 4 K. Together with these periodic table of elements. A high improvements, the high temperature performance electron cyclotron resonance superconducting (HTS) materials have ion source is the most suitable choice with gained more popularity over low temperature the constraint that the ion source has to be superconducting (LTS) materials due to their operated on a 400 kV high voltage platform 118 Performance prediction and test results
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Performance prediction and test results of LOX tank pressurisation system of cryogenic propulsion stage tested in ISRO facility Performance prediction and test results of LOX tank pressurisation system of cryogenic propulsion stage tested in ISRO facility M. Xavier, P.P. Kailasanathan and Ashish K. Kartikeya
M. Xavier, P.P. Kailasanathan and Ashish K. Kartikeya Cryogenic Propulsion Stages Group, LPSC /ISRO, Thiruvananthapuram, India Cryogenic Propulsion Stages Group, LPSC /ISRO, Thiruvananthapuram, India
Indian space research organisation has successfully completed the ground testing of a cryogenic propulsion stage using LOX and LH2 as propellant. This stage has propellant loading of 15,700 kg and engine thrust of 75 kN. Out of 15,700 kg of propellant, about 13,300 kg of LOX is stored in a foam insulated tank at sub-cooled condition and is pressurised by a cold gas pressurisation system during engine operation. Two gas bottles made of titanium alloy are kept inside LOX tank for storing helium gas at 22 MPa and 80 K and is regulated to 0.17 MPa by tank pressurisation module. This is to meet the net positive suction head required for the booster pump mounted inside the LOX tank. Helium bubbler circuit provided as part of tank pressurisation system stirs up the LOX and keeps the liquid uniformly mixed in the tank during engine operation. The pressurisation process is mathematically modeled incorporating heat transfer effect of pressurant gas inside the ullage volume, thermodynamic change of helium in gas bottle, helium mass consumption from gas bottle to maintain the required tank pressure, pressure fall trend in gas bottle during engine operation etc. This paper presents the test scheme, system configuration and comparison of pre-test predictions and test results.
Key words: LOX tank, Cryogenic propulsion stage, Helium gas, Pressurisation system
INTRODUCTION configured for 15,700 kg propellant loading capacity and engine thrust of 75 kN. Liquid propulsion systems centre of Indian LOX tank pressurisation system is one of space research organisation had embarked the sub-systems employed in the above test on the development of cryogenic propulsion hardware for evaluating its performance stage in the early 1990s to substitute the during engine operation phase. This system cryogenic stages procured from Russia for the uses helium gas stored in high pressure launches of Geosynchronous satellite launch cryogenic gas bottle as pressurant and is vehicle (GSLV). This stage has large number regulated through regulator module for LOX of design improvements and system simplicity tank pressure maintenance. compared to the procured stage. The maiden This paper outlines the mathematical flight stage, which is in a advanced stage of formulation of the pressurisation system and integration, has propellant loading capacity of the computer program developed for 12,500 kg while the future stages will have predicting its performance during long 15,000 kg capacity. Considering this duration hot test. Also, the hot test data is requirement, development test hardware was 124 Performance investigation of pulse tube refrigerator
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009 Performance investigation of pulse tube refrigerator using straight and stepped pulse tubes Lokanath Mohanta, M.D. Atrey Refrigeration and Cryogenics Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai – 400 076
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Analysis of irradiation problems in optical cryocooler
Biju T. Kuzhiveli1, Subhash Jacob2
1Department of Mechanical Engineering National Institute of Technology Calicut, India-673601, 2Indian Institute of Science, Bangalore-560 012 Email: [email protected]
A network matrix method has been envisaged and developed to encompass complicated combined heat transfer mechanism associated with all solid state optical cryocooler. A numerical solution and computer program package has been made to asses the radiation penalties caused by external and different internal surfaces of an optical cryocooler. The network matrix method so developed is unique in its nature and been able to incorporate all the heat transfer modes. The study takes in to account of the following factors which can affect performance of the cryocooler: Radiation coupling between the optical material and the sink, effect of shape factors and emmisivities, influence of heat generation and absorption on the elements of the cryocooler, effect of conductivities of different materials used in the construction, Influence of connecting wires to cryotip, sensors and optical material, contribution of laser heat etc.
Key words: cryocooler, phonon, photon, emissivity
INTRODUCTION glass doped with a rare earth ion that has spectrally broad ground and excited states Optical refrigeration is based on absorbing (refer figure 1). light on the low energy side of a material Each energy state or a manifold absorption spectrum and re-emission at consists of several closely spaced levels that higher energies after equilibration with the are in thermal equilibrium among each other thermal vibrations of the solid. Anti-Stokes and undergo the following processes: (1) fluorescence is the phenomenon by which a Laser pumping: electrons in the upper level of substance is excited by radiation at one the ground-state manifold are pumped to the wavelength ~1060 to1030 nm and fluoresces lower level of the excited-state manifold. at a shorter wave length typically ~995 nm. During this process thermal equilibrium within This results in more energy being radiated each manifold is upset. The upper level of the than is absorbed for each photon. A multi-watt ground state manifold is under populated and laser is focused on to a nearly transparent the lower level of the excited state manifold is material to accomplish this task. Utilizing this overpopulated. (2)Energy absorption from the process for cooling may at first, appear to be thermal bath: the population of the energy a misnomer which violates thermodynamic levels re-equilibrate through phonon (heat) principles. A closer look at a specific cooling absorption. Both manifolds quickly return to process reveals how this works. Consider a equilibrium by absorbing phonons from the Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009 Theoretical analysis of sorption compressor for J–T cryocooler 1,2 1 1 Rohit Mehta , S.L.Bapat , M.D.Atrey 1Department of Mechanical Engineering, IIT Bombay Mumbai - 400076 2Government Engineering College Bharuch Gujarat - 392002 Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
TheoreticalTheoretical Modelmodel forfor Thermoacousticthermoacoustic devicesDevices
S. Mehta1, H. B. Naik1, K. P. Desai1, M.D.Atrey2
1Mechanical Engineering Department, S.V. National Institute of Technology, Surat 2 Mechanical Engineering Department, IIT Bombay, Mumbai
The Pulse Tube Cryocooler has the chief advantage of not having any moving component in the cold region. However it does require a mechanical compressor. If this mechanical compressor is replaced by a thermoacoustic prime mover then the system will be without any moving component. Design and development of a thermoacoustic prime mover is a challenging work. This requires thorough understanding of thermoacoustic phenomenon. The performance of a thermoacoustic prime mover depends upon various parameters viz. heat input, hot and cold end temperatures, stack type, geometrical dimensions of different components, mean pressure etc. These parameters are correlated by Rott’s wave equation [1]. The present work aims to solve Rott’s wave equation in various components of a thermo acoustic device. The results obtained will be compared with those available in the literature [8].
Key words: Pulse tube, Thermoacoustic Prime mover, Wave Equation
INTRODUCTION can be used directly to drive a pulse tube cooler to realize a cooling system without any With wide application of cryocoolers, stability moving part. Two of the most important becomes a key problem for their further advantages of thermoacoustic prime mover development. One of the effective means is to are, ‘there are no moving components except eliminate moving components. Pulse tube is for the movement of the working fluid’ and ‘it most reliable and most long-lived coolers, can be driven by “heat energy”, which can which is in great demand in rapidly advancing utilize “solar energy”, “fuel gas” etc’. However, space technology. There is no moving part in low efficiency of the thermoacoustic driver is a pulse tube cooler except the unit supplying one of the barriers to further development of an oscillating gas flow. A thermoacoustic this refrigeration method. prime mover instead of a mechanical The thermoacoustic Prime mover compressor to drive a pulse tube is a generates the sound. Sound waves in gas are promising refrigeration concept. Moreover, usually expressed in terms of oscillations of pulse tube and thermoacoustic prime mover displacement and pressure. Temperature usually use the same gas as working fluid. It oscillations also exist together with pressure means that a thermoacoustic prime mover oscillations. In the Thermoacoustic prime Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Modeling of inertance tube based on RLC circuit analogy Sarkar M. and Atrey M. D. Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India. 152 Relationship between the composition of a four component
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Relationship betweenBetween thethe compositionComposition of of a a four Four component Component nitrogen-hydrocarbon Nitrogen-Hydrocarbon mixtureMixture chargedCharged intointo thethe systemSystem and and that that in in circulation Circulation during During steady Steady state State operationOperation of of a a J-T J-T refrigerator Refrigerator
N.N. Lakshmi Lakshmi Narasimhan, Narasimhan, S. S. Srinivasamurthy Srinivasamurthy and and G.Venkatarathnam G.Venkatarathnam RefrigerationRefrigeration and and Airconditioning Airconditioning Laboratory, Laboratory, Dept. Dept Mech. Mech Engg., Engg., IIT IIT Madras, Madras, Chennai-36,Chennai-36, India.
Joule Thomson (JT) cryocoolers are small refrigerators that can provide refrigeration at temperatures in the range 30-200 K. JT cryocoolers operating with mixed refrigerants are being studied worldwide including our laboratory. Previous studies have shown that the performance of JT cryocoolers is markedly influenced by the composition of mixtures in circulation. The mixture composition in circulation is quite different from that charged into the system due to the solubility of some of the components in the compressor lubricating oil as well as the liquid hold up in the heat exchanger. In the present work, the variation of composition during circulation of four component nitrogen-hydrocarbon mixed refrigerants operating in a single stage Joule-Thomson cryocooler has been investigated experimentally. A method has been developed to predict the composition of the refrigerant to be charged for obtaining a desired mixture in circulation based on the experimental data. The efficacy of the method has been tested experimentally. The details of the experiments performed, results obtained and the basis of the method are presented in this paper.
Key words: JT cryocoolers, mixed refrigerants, composition variation
INTRODUCTION carried out in the past regarding the optimization of refrigerant mixtures and Progress in mixed refrigerant (MR) performance characteristics of JT cryocoolers technology has considerably improved the operating with mixed refrigerants. Longsworth development of Joule Thomson (JT) et al. [1] presented a thermodynamic analysis cryocoolers to provide refrigeration at on different nitrogen-hydrocarbon based temperatures down to 60 K with an mixtures as well as experimental studies. The acceptable reliability. Prominent applications lowest temperature achieved was 79 K. Khatri of JT cryocoolers are the cooling of MR, and Boiarski [2] showed experimentally that SQUIDS, missiles, cryosurgery, space, etc., temperatures as low as 70 K could be where refrigeration is needed at cryogenic achieved with the addition of helium to temperatures. JT cryocoolers offer several nitrogen-hydrocarbon mixtures. Arkhipov et al. advantages such as low vibration and noise, [3] have carried out both analytical and separation of the compressor unit and cold experimental studies on JT cryocoolers and head, low operating pressures, use of off-the found the addition of Ne above 6-15% to N2- shelf airconditioning compressors, low HC mixtures could result in refrigeration electromagnetic interference, miniaturization, temperatures down to 65 K. Boiarski et al., [4] easy integration to critical electronic developed a software to optimize the design components, etc. Several studies have been of a JT cryocooler by performing a system 158 High frequency pulse tube refrigerator for 100 K
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009 High frequency pulse tube refrigerator for 100 K C.V.Thaokar and M.D. Atrey Refrigeration and Cryogenics Laboratory Department of Mechanical Engineering Indian Institute of Technology Bombay, Powai, Mumbai – 400 076 164 Comparison of stirling type pulse tube refrigerators by CFD simulations
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
ComparisonComparisonComparison of of ofStirling Stirling Stirling Type Type Type Pulse Pulse Pulse Tube Tube Tube Refrigerators Refrigerators Refrigerators byby by CFDCFD CFD SimulationsSimulations Simulations Comparison of stirling type pulse tube refrigerators by CFD simulations
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Pulse tube refrigerators have no moving parts in the cold region. It brings longlife operation, high reliability,Pulse Pulse Pulse tube tube tube and refrigerators refrigerators refrigerators low vibration have have have at no no the nomoving moving coldmoving parts section.parts parts in in the in Inthe the thiscoldcold cold paper, region.region. region. the ItIt brings bringsIt commercial brings long-long- long- lifelifelifecomputational operation, operation, operation, high high fluid high reliability, reliability, dynamic reliability, and (CFD) and and low low lowpackage vibration vibration vibration Fluent atat theat the is the cold coldutilized cold section. section. section. for twodimensional In In this In this this paper, paper, paper, axis- the the the commercialcommercialcommercialsymmetric computational modeling computational computational of entire fluid fluid fluid inertance dynamic dynamic dynamic tube (CFD) (CFD) (CFD) pulse package package tube package refrigerator Fluent Fluent Fluent is is (ITPTR) utilizedis utilized utilized and for for for orifice two- two- two- dimensionaldimensionaldimensionalpulse tube axis-symmetricrefrigerator axis-symmetric axis-symmetric (OPTR). modeling modeling modeling In order of of to ofent entcompare entireire ire inertance inertance inertancethe performance tube tube tube pulse pulse pulse of tubeITPTR tube tube refrigerator refrigerator and refrigerator OPTR (ITPTR)(ITPTR)(ITPTR)by CFD and andand simulation, orifice orifice orifice pulse pulse pulse a sametube tube tube refrigerator compressionrefrigerator refrigerator (O (O PTR).(O andPTR).PTR). expansion In In order Inorder order to to process compare tocompare compare and thethe athe performance performance same performance piston of ofofmovement ITPTR ITPTR ITPTR and and and was OPTR OPTR OPTR applied by by by CFD for CFD CFD both simulation, simulation, simulation, the systems a a same a same same that compression compression were compression geometrically and and and expansion expansion similar expansion except process process process the andandandinertance a asamea samesame tubepiston piston piston in ITPTRmovement movement movement is replaced was was was applied applied by applied an fororifice for forboth both bothvalve the the the insystems systems OPTR. systems thatThethat that weregeneralwere were geometricallygeometrically resultsgeometrically such similarsimilarsimilaras phase except exceptexcept relations the the the inertance inertance inertance between tube tube tube mass in in ITPTRin ITPTR flow ITPTR rateis is replaced isreplaced and replaced pressure, by by byan an anorifice massorifice orifice flowvalvevalve valve rate inin OPTR. OPTR.in at OPTR. cold TheThe end The generalgeneralgeneralsection, results results resultstemperature such such such as as ascontourphase phase phase relations alongrelations relations the between betweenaxial between direction, mass mass mass flow flow velocity flow rate rate rate and andvectors and pressure,pressure, pressure, in pulse massmass tubemass flowflow are flow raterateratepresented at atcoldat cold cold end for end end bothsection, section, section, the modelstemperature temperature temperature to compare contour contour contour their along along alongperformance. the the the axial axial axial direction, direction,Results direction, showed velocityvelocity velocity that vectorsvectors vectorsthe use inin in pulsepulsepulseof the tube tubeITPTR tube are are areconfi presented presented presentedguration for offers for for both both botha thebetter the the model model potential modelss tos to compareforto compare comparehigher theirperformance their their performance. performance. performance. and effi Results Resultsciency. Results showedshowedshowed that that that the the the use use use of of of the the the ITPTR ITPTR ITPTR configuration configuration configuration offers offers offers a a better abetter better potential potential potential for for for higher higher higher performanceperformanceperformance and and and efficiency. efficiency. efficiency.
Keywords:Keywords:Keywords: Orifice Orifice Orifice pulse pulse pulse tube, tube, tube, Inertance Inertance Inertance pulse pulse pulse tube, tube, tube, dual dual dual opposed opposed opposed piston piston piston compressor,compressor, compressor, Fluent.Fluent. Fluent.
IntroductionIntroductionIntroduction refrigeratorrefrigeratorrefrigerator (DIPTR) (DIPTR) (DIPTR) by by by adding adding adding a a double doublea double inletinletinlet valve valve valve in in in an an an orifice orifice orifice pulse pulse pulse tube tube tube BasicBasicBasic pulse pulsepulse tube tube tube refrigerator refrigerator refrigerator (BPTR) (BPTR) (BPTR) refrigerator,refrigerator,refrigerator, which which which improved improved improved the the waswaswas originally originally originally proposed proposed proposed by by by Gifford Gifford Gifford and and and refrigerationrefrigerationrefrigeration performance performance performance significantly. significantly. significantly. LongsworthLongsworthLongsworth [1] [1] [1] in in in 1964. 1964. 1964. Mikulin Mikulin Mikulin et et et al. al. al. [2] [2] [2] ManyManyMany theoreticaltheoretical theoretical analysisanalysis analysis methods,methods, methods, as aswell well mademademade an anan important importantimportant improvement improvementimprovement by by byadding adding adding asas as numericalnumerical numerical modelsmodels models havehave have beenbeen been developeddeveloped developed ananan orifice orifice orifice valve valve valve between between between pulse pulse pulse tube tube tube and and and toto to investigate investigate investigate the the the mechanism mechanism mechanism of of reservoirreservoirreservoir to to to improve improve improve the the the performance performance performance of of of refrigerationrefrigerationrefrigeration and and and intrinsic intrinsic intrinsic loss loss loss [4-6]. [4-6]. BPTR.BPTR.BPTR. This This This modification modification modification leads leads leads to to to orifice orifice orifice However,However,However, the the the exact exact exact nature nature nature of of theof the the physical physical pulsepulsepulse tube tube tube refrigerator refrigerator refrigerator (OPTR). (OPTR). (OPTR). The The The phenomenaphenomenaphenomena underlying underlying underlying the the the operation operation operation of of inventioninventioninvention of of of this this this simple simple simple OPTR OPTR OPTR is is is regarded regarded regarded PTRsPTRsPTRs is is so isso sofor for fornot not not well-understoodwell-understood well-understood [7].[7]. [7]. Up Upto to asasas the the the milestone milestone milestone of of of the the the developments developments developments of of of now,now,now, most most most of of ofthese these these approaches approaches approaches are are are based based pulsepulsepulse tube tube tube refrigerator. refrigerator. refrigerator. Zhu Zhu Zhu et et et al. al. al. [3] [3] [3] onon onthe the the assumption assumption assumption ofof one-dimensionalofone-dimensional one-dimensional flow, flow, proposedproposedproposed a adoublea doubledouble inlet inlet inlet pulse pulse pulse tube tube tube 170 Numerical analysis of performance and loss mechanisms
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Numerical analysis of performance and loss mechanisms of a Numerical Analysistwo-stage of Performance pulse tube and cryocooler Loss Mechanisms of a Two-Stage Pulse Tube Cryocooler
S.Kasthurirengan1, Upendra Behra1, Rahul N. Sagar1, K.V.Dinesh1, 2 2 N.K.1 Mohammed Sajid1 , K.A. Shafi 1 1 S.Kasthurirengan , Upendra Behra , Rahul N Sagar , K V Dinesh , N.K. Mohammed Sajid2, K.A Shafi2 1 1Centre for Cryogenic Technology, Indian Institute of Science, Bangalore, 560012, India. Centre for Cryogenic2 Technology, Indian Institute of Science, Bangalore, 560012, India. 2TKM College of Engineering,Kollam,Kerala,691005,India. TKM College of Engineering,Kollam,Kerala,691005,India.
The importance of Pulse Tube Cryocoolers (PTC) has grown rapidly in the last two decades due to the absence of moving parts at cryogenic temperatures, high mechanical stability and reliability for long-term performance. Although commercial PTCs are available, the basic mechanisms of cooling are still a subject of detailed studies and hence many numerical models have been used. The theoretical analysis of PTC has been carried out using an one dimensional adiabatic model, assuming real gas properties of the working fluid. The refrigeration power is determined taking into account of various loss mechanisms such as axial heat conduction through the walls of pulse tube and regenerator matrix, regenerator ineffectiveness, pressure drop and radiation from the ambient. A heat balance analysis is carried out for the second stage to understand the relative magnitudes of various losses. The predicted refrigeration power and temperature profiles have been compared with the available experimental results. The reasonably good agreement between them indicates the validity of the model developed here.
Keywords: Pulse tube, Cryocooler, Regenerator, Cooling power, Numerical model
INTRODUCTION significant improvements of this cooler have been achieved by addition of a buffer volume There have been significant developments in and an orifice to produce the phase shift the area of cryocoolers such as Gifford between mass flow rate and pressure of the McMahon, Stirling and Pulse Tube (PT) etc. working fluid (known as orifice PTC). The over the last few decades. Of these, Pulse next significant improvement resulted by the Tube Cryocoolers (PTC) offer significant addition of a second orifice between the warm advantages such as lower vibration levels, ends of the PT and regenerator (called double greater reliability by the absence of moving inlet PTC). This reduces the mass flow components at low temperatures, and hence through the regenerator resulting in reducing are chosen for various applications such as the no-load temperature of single stage cooling of devices and superconducting system down to ~30K [2]. Using staging, one magnets, recondensation of cryogenic liquids, could reach liquid helium temperatures [3]. cryo-pumping etc. Since the discovery of Although commercial PTCs are available as basic PTC by Gifford and Longsworth [1], on date, the basic cooling mechanisms in 176 Characterisation of adsorption compressor used in a charcoal–nitrogen adsorption cryocooler
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Characterisation of Adsorption Compressor Used in a Charcoal – Nitrogen Characterisation of adsorptionAdsor pcompressortion Cryoco usedoler in a charcoal – nitrogen adsorption cryocooler
Leena.R1, M. Jose Prakash2 Leena. R1 and M. Jose Prakash2
1 1DDepartmentepartment ooff MMechanicalechanical EEngineering,ngineering, Y Younusounus CCollegeollege ooff EEngineeringngineering aandnd T Technology,echnology, KKollam,691010ollam,691010 2 Depa2rDepartmenttment of Me cofh aMechanicalnical Engin eEngineering,ering, TKM CTKMolleg Collegee of Eng ofin eEngineering,ering, Kollam Kollam,, 69100 691005,5, Kerala Kerala
Adsorption refrigeration is a relatively new breakthrough in the field of cryogenic cooling. A knowledge of the adsorption compressor characteristics is necessary to calculate the cooling load the cryocooler can cater to. A procedure for simulating the compressor characteristics is described. Although the procedure is tested for a charcoal - nitrogen system, this scheme can be used for any adsorbent adsorbate pair. The temperature distribution in the adsorbent bed, which is necessary for the simulation is obtained using finite difference method. It is observed that by increasing the packing density of the adsorbent, higher operating pressure in the compressor cycle can be achieved and the throughput of the gas can be increased. It is also observed that for a given packing density there is a limit to the higher operating pressure that can be attained. With this simulation extensive experimentation to characterise the compressor can be avoided.
Key words: Cryocooler, Charcoal, Adsorption, Simulation
INTRODUCTION Adsorption cryocoolers are becoming recognized as a very attractive refrigeration Cryocoolers are required to maintain method for long duration space borne applic- temperatures of detectors of electro-optical ations in the 4-150K range. Their positive devices in on-board satellites, space stations features are (i) no moving parts are involved etc. used for i) application oriented missions in the thermal compressor (ii) negligible vibra- such as weather monitoring, remote sensing tion and electromagnetic interference, (iii) the and surveillance ii) high energy gamma ray compressor can be scaled to accommodate astronomy, ii) infra red (IR) astronomy and iv) different heat loads and (iv) compressor can superconductivity missions. The operating be powered by waste heat or extra terrestrial temperatures of these detectors range from 1 solar energy. The principle of operation of to 200 K and typical heat loads range from sorption cryocooler is well documented[1-5]. 0.1mW to 10W. For space applications, the primary considerations are low weight, low PRINCIPLE OF OPERATION operating power requirement and reliability The basic components of an adsorption over long duration (of the order of a few cryocooler are a thermal compressor, a pre- years). cooler, a recuperative heat exchanger and a 182 Developmental studies on low mass cryocooler
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Developmental studies on low mass cryocooler Developmental Studies on Low Mass Cryocooler
Ramasamy, A., Padmanabhan and Gurudath, C.S.
Thermal Systems Group, ISRO Satellite Centre, Bangalore-560 017, India
ISRO Satellite Centre (ISAC) has developed and completed the technology demonstration phase of a single stage split Stirling cryocooler for cooling of onboard IR Detectors. The development model has capability to provide 80K temperatures with 1W load for an input power of 25W. The mass of the present development model is around 11 kg, which is high compared to the present development trends that are reported in literature. To realize the low mass cryocooler (<4kg) for space applications, developmental studies were done, from which it is concluded that it is possible to realize a cryocooler whose mass can be less than 4 kg for cooling capacity of 1W at 80K.
Keywords: cryocooler, development, space application
INTRODUCTION BACKGROUND
Cryogenic cooling with compact, low mass and ISAC has demonstrated the thermal high reliability cryocooler is required for future performance of single stage Stirling cryocooler ISRO missions. Cryogenic cooling is required and reported the technology maturity [1]. The for cooling the infrared detector on spacecraft performance of this developed model (DM) is for improving the signal to noise ratio. For this comparable to the performance of units made purpose, various techniques exist to cool the by other space agencies. During this detector. ISAC has developed and development phase, various issues related to demonstrated the thermal performance of the hardware fabrication, assembly and testing single stage split Stirling cryocooler [1] whose were sorted out / learned. A few more units mass is around 11 kg. were made and demonstrated the Any unit that goes on the spacecraft performance consistency. After acquiring this should have low mass and power for the technology, one of the units was converted required functional aspects. Currently, coolers into two-stage Stirling cryocooler and it’s with mass of 4 kg or less are being used in performance was reported earlier [2]. The satellites made by other space agencies. To mass of this unit is around 12 kg. Because of realize such low mass, long life cryocooler for the higher mass, further development has Indian satellites, various development been diverted to low mass cryocooler (LMC). approaches are being studied and this paper Mass less than 4 kg is called as low mass presents the same and current development cryocooler in this development. status. Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Magnetocardiogram and magnetoencephalogram using a SQUID based system 192 Effect of tempering on the cryotreated intergral diaphragm pressure transducers
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
Effect of Tempering on the Cryotreated Intergral Diaphragm Pressure Effect of tempering onTransducers the cryotreated intergral diaphragm pressure transducers
Nadig D.S.+, Jacob S. +, Karunanithi R.+, Manjunatha. R+, Patil. S+ & Subramanian D.*, Prasad M.V.N.*, Geetha Sen* +Centre for Cryogenic Technology, Indian Institute of Science, Bangalore – 560 012, India *Liquid Propulsion System Centre, ISRO, Bangalore, India
Any machined component develops residual stresses during machining and heat treatment. In many cases, the presence of these induced residual stresses are seriously detrimental for the functional reliability of the system. In this study, a cryotreatment system is designed and developed to reduce the residual stresses induced within the integral diaphragm of the pressure transducers during machining. These pressure transducers machined out of precipitation-hardened stainless steel were cryotreated for 24 hours at 98K. The residual stress results of cryotreated transducers indicated significant reduction. These reductions have reduced the problems of zero shift of the outputs of transducers
Key words: Residual stress, Martensite, Austenite, Tempering
INTRODUCTION (cooling period), held for extended length of time (soak time) and gradual warming The practice of cryogenic treatment on metals (warming time) to room temperature. In normal has been done extensively over years mainly practice a complete cryotreatment cycle takes for applications like stabilization of close around 36 hours with 5 hours of cooling, 24 toleranced machine parts of hours of soaking and 7 hours of warming. watches,improvement in tool life of cutting tools These parameters can be modified for etc. The results of cryotreatment on cutting optimized results. tools have been definitely encouraging. However, there is large scope for research to study the effect of cryogenic treatment in various areas like removal of residual stresses, conversion of Retained Austenite to Martensite in steels etc. The effects of Cryotreatment to reduce the residual stresses of Internal Diaphragm Pressure Transducers used for measurement of propellant pressures are discussed in this paper. Figure 1. Cryo-Treatment Cycle A typical Cryo treatment cycle involves mainly 3 phases where the metal samples are When metals are gradually cooled to cryogenic cooled gradually to cryogenic temperature temperatures, soaked for a prolonged period
1 196 Cryogenically multiplexed discrete array type liquid
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
202 A numerical model for prediction of effective thermal conductivity
Indian Journal of Cryogenics Vol. 34. No. 1-4, 2009
A numerical model for prediction of effective thermal conductivity of perforated plates in matrix heat exchangers
S. Sunil Kumar and T. K. Nandi Cryogenic Engineering Centre, IIT, Kharagpur, WB-721 302
Effective thermal conductivity (keff) of the perforated plates is essential for design and optimization of matrix heat exchangers (MHEs). The cylindrical holes in the plates may be arranged in square or hexagonal array. Published data show that for porosity up to 0.6, which mostly covers the MHE applications, the keff values for square and hexagonal arrays are very close. Thus, the keff values for square array can also be used for hexagonal array (up to porosity 0.6). This paper presents a numerical model using finite difference method for predicting keff of plates having holes in square array. The results obtained are compared with the available experimental data and with the data obtained from analytical expressions. An appropriate correlation suitable for the design of MHEs is also identified.
Key words: Perforated plates, effective thermal conductivity, matrix heat exchanger
INTRODUCTION
Matrix heat exchangers (MHEs) offer high effectiveness, large surface area per unit volume (>6000m2/m3) and better flow characteristics [1]. Construction wise an MHE comprises a stack of alternate layers of high thermal conductivity perforated plates and low thermal conductivity insulating spacers, which are bonded together to form leak free passages for the heat exchanging fluids [2-3]. Fig.1 shows longitudinal section of an MHE. Thermal resistances in heat flow path include convective resistance between the hot fluid and the plate, conduction resistance along the plate and convective resistance between the plate and the cold fluid [4]. Heat transfer characteristics of MHEs are affected by plate geometry, plate thickness, porosity, hole size, and hole arrangement. Hole centre pitch P and radius of the holes R are related Fig.1 Longitudinal section of an MHE to the porosity of a perforated plate with holes 2 2 decrease. This will increase conductive in square array by f = πR /P . Hence if R is resistance of the perforated plate. The benefit constant and P is too small, f will increase of increase in heat transfer area due to and the metal width from hole to hole will