DOCSLIB.ORG

Thermodynamic Analysis of Three Compressed Air Energy Storage Systems: Conventional, Adiabatic, and Hydrogen-Fueled

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Thermodynamic Analysis of Three Compressed Air Energy Storage Systems: Conventional, Adiabatic, and Hydrogen-Fueled energies Article Thermodynamic Analysis of Three Compressed Air Energy Storage Systems: Conventional, Adiabatic, and Hydrogen-Fueled Hossein Safaei and Michael J. Aziz * Harvard John A. Paulson School of Engineering and Applied Sciences, Pierce Hall, 29 Oxford Street, Cambridge, MA 02138, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-617-495-9884 Received: 10 May 2017; Accepted: 27 June 2017; Published: 18 July 2017 Abstract: We present analyses of three families of compressed air energy storage (CAES) systems: conventional CAES, in which the heat released during air compression is not stored and natural gas is combusted to provide heat during discharge; adiabatic CAES, in which the compression heat is stored; and CAES in which the compression heat is used to assist water electrolysis for hydrogen storage. The latter two methods involve no fossil fuel combustion. We modeled both a low-temperature and a high-temperature electrolysis process for hydrogen production. Adiabatic CAES (A-CAES) with physical storage of heat is the most efficient option with an exergy efficiency of 69.5% for energy storage. The exergy efficiency of the conventional CAES system is estimated to be 54.3%. Both high-temperature and low-temperature electrolysis CAES systems result in similar exergy efficiencies (35.6% and 34.2%), partly due to low efficiency of the electrolyzer cell. CAES with high-temperature electrolysis has the highest energy storage density (7.9 kWh per m3 of air storage volume), followed by A-CAES (5.2 kWh/m3). Conventional CAES and CAES with low-temperature electrolysis have similar energy densities of 3.1 kWh/m3. Keywords: compressed air energy storage (CAES); adiabatic CAES; high temperature electrolysis; hydrogen storage; thermodynamics 1. Introduction Large penetrations of wind and solar energies challenge the reliability of the electricity grid, due to their intermittency and uncertainty. Storage technologies are being developed to tackle this challenge. Compressed air energy storage (CAES) is a relatively mature technology with currently more attractive economics compared to other bulk energy storage systems capable of delivering tens of megawatts over several hours, such as pumped hydroelectric [1–3]. CAES stores electrical energy as the exergy of compressed air. Figure1 is a simplified schematic of a CAES plant. Electricity is supplied by the grid to run the air compressors and charge the storage system. Waste heat is released during the compression phase. Air is stored for later use—often in an underground cavern. During the discharge phase, compressed air is combusted with a fuel, and expanded in a turbine (expander) to regenerate electricity. Currently, there are two commercial CAES plants in operation: Huntorf in Germany (since 1978) and McIntosh in USA (since 1991) [4]. Moreover, there are some smaller projects in operations or in construction and planning phases, most notably General Compression’s 2 MW, 300 MWh project in Texas, USA and SustainX’s 1.5 MW, 1 MWh project in New Hampshire, USA [5]. Energies 2017, 10, 1020; doi:10.3390/en10071020 www.mdpi.com/journal/energies Energies 2017, 10, 1020 2 of 31 Energies 2017, 10, 1020 2 of 31 Figure 1. SchematicSchematic of a generic conventional compressed air energy storage (CAES) system. The prospects forfor the the conventional conventional CAES CAES technology technology are are poor poor in low-carbonin low-carbon grids grids [2,6 –[2,6–8].8]. Fossil Fossil fuel (typicallyfuel (typically natural natural gas) combustiongas) combustion is needed is needed to provide to provide heat to heat prevent to prevent freezing freezing of the moisture of the moisture present presentin the expanding in the expanding air [9]. air Fuel [9]. combustion Fuel combustion also boosts also boosts the work the outputwork ou intput comparison in comparison to solely to solelyharnessing harnessing the energy the energy stored stored in the compressedin the compressed air. air. We develop analytical models to assess the thermodynamicsthermodynamics of two strategies to make CAES greenhouse gasgas (GHG) (GHG) emissions-free. emissions-free. Both Both utilize utilize the temperature the temperature increase fromincrease the airfrom compression the air processcompression to eliminate process the to needeliminate for gas the combustion. need for gas This combustion. heat is generated This heat during is generated the charging during phase. the chargingBecause ofphase. its low Because temperature of its low and temperature correspondingly and lowcorrespondingly exergy, the compression low exergy, heatthe compression is rejected to heatthe ambient is rejected environment to the ambient in the conventionalenvironment CAESin the setup.conventional This heat CAES could, setup. in principle, This heat be could, stored in to principle,heat the expanding be stored airto providedheat the expanding that the temperature air provided of this that stored the temperature heat is high enough.of this stored The primary heat is highmethod enough. to achieve The primary such high method temperatures to achieve is to such increase high thetemperatures operating pressureis to increase of the the compressors operating pressureand to eliminate of the intercoolingcompressors between and to compression eliminate stagesintercooling (i.e., adiabatic between compression). compression This, stages however, (i.e., posesadiabatic practical compression). challenges This, due however, to high operatingposes practical pressures challenges and temperatures due to high operating of the compressors pressures (e.g.,and temperatures metallurgical of limits the compressors on compressor (e.g., blades). metallurgical limits on compressor blades). Physical storage of the compression heat is the core of the Adiabatic CAES (A-CAES) concept—the first first carbon-free CAES system we investigate.investigate. Chemical storage of the compression heat in the form of hydrogen, and combustion of hydrogen instead of natural gas during the discharge phase is is the the second second strategy strategy we we analyzed analyzed.. Hydrogen Hydrogen can can bebe produced produced via via electrolysis electrolysis of steamof steam at athigh high temperatures temperatures (HTE) (HTE) or or water water at at lo loww (ambient) (ambient) temperatures temperatures (LTE). (LTE). The The HTE HTE concept benefitsbenefits fromfrom the the lower lower electricity electricity demand demand of the of electrolysis the electrolysis process process at higher at temperatures.higher temperatures. Utilizing Utilizingthe high-temperature the high-temperature heat of compression heat of compression lowers the lowers electricity the demandelectricity of demand hydrogen of production hydrogen productionin the CAES-HTE in the CAES-HTE system. This system. saving This is achieved saving is at achieved the expense at the of higherexpense electricity of higher demand electricity of demandthe air compressor of the air compressor which, in CAES-HTE,which, in CAES-HTE, operates atop highererates at pressures higher pressures with limited with or limited no cooling. or no Thecooling. CAES-LTE The CAES-LTE concept isconcept comparable is comparable to the conventional to the conventional CAES system CAES (diabatic system compression (diabatic withcompression the use ofwith coolers the use between of coolers compressor between stages).compressor However, stages). hydrogen However, is hydrogen produced is onsite produced with onsitea low-temperature with a low-temperature electrolyzer. electrolyzer. Electrolysis of steam (HTE) instead of water (L (LTE)TE) requires more thermal but less electrical energy. FigureFigure2 illustrates2 illustrates the the theoretical theoretical energy energy requirements requirements as functions as functions of the electrolysis of the electrolysis reaction reactiontemperature temperature (see Appendix (see AppendixA for details). A for In adetails). high-temperature In a high-temperature electrolyzer, steamelectrolyzer, is disassociated steam is disassociatedin the cathode in to the produce cathode hydrogen to produce and Ohydrogen2−, while andO2− Ois oxidized, while O in the is anodeoxidized to producein the anode oxygen. to Theproduce theoretical oxygen. total The theoretical energy demand total energy of the demand electrolysis of the process electrolysis (change proc iness enthalpy, (change inDH enthalpy,) equals ΔtheH) electricity equals the demand electricity (reversible demand work, (reversible i.e., change work, in thei.e., Gibbschange free in energy,the GibbsDG )free plus energy, the heat Δ demandG) plus theof the heat reaction demand (change of the inreaction entropy (change multiplied in entropy by the multiplied reaction temperature, by the reactionDS ×temperature,T) from a source ΔST of) fromat least a source as high of a temperatureat least as high as thea temperature reaction temperature. as the reaction While temperature. the total energy While demand the total (enthalpy energy demandchange) of(enthalpy electrolyzing change) steam of electrolyzing increases at highersteam in temperatures,creases at higher its electricity temperatures, demand its decreases.electricity Thedemand savings decreases. in electricity The savings consumption in electricity of the consumpt electrolyzerion come of the at electrolyzer the expense come of its at higher the expense heat load. of Therefore,its higher heat electrolysis load. Therefore, of steaminstead electrolysis of water of stea couldm instead be particularly of water attractive
Load more

Recommended publications
  • Heat Transfer Model of a Rotary Compressor S
    Purdue University Purdue e-Pubs International Compressor Engineering Conference School of Mechanical Engineering 1992 Heat Transfer Model of a Rotary Compressor S. K. Padhy General Electric Company Follow this and additional works at: https://docs.lib.purdue.edu/icec Padhy, S. K., "Heat Transfer Model of a Rotary Compressor" (1992). International Compressor Engineering Conference. Paper 935. https://docs.lib.purdue.edu/icec/935 This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] for additional information. Complete proceedings may be acquired in print and on CD-ROM directly from the Ray W. Herrick Laboratories at https://engineering.purdue.edu/ Herrick/Events/orderlit.html HEAT TRANSFER MODEL OF A ROTARY COMPRESSOR Sisir K. Padhy General Electric C_ompany Appliance Park 5-2North, Louisville, KY 40225 ABSTRACT Energy improvements for a rotary compressor can be achieved in several ways such as: reduction of various electrical and mechanical losses, reduction of gas leakage, better lubrication, better surface cooling, reduction of suction gas heating and by improving other parameters. To have a ' better understanding analytical/numerical analysis is needed. Although various mechanical models are presented to understand the mechanical losses, dynamics, thermodynamics etc.; little work has been done to understand the compressor from a heat uansfer stand point In this paper a lumped heat transfer model for the rotary compressor is described. Various heat sources and heat sinks are analyzed and the temperature profile of the compressor is generated. A good agreement is found between theoretical and experimental results. NOMENCLATURE D, inner diameter D.
    [Show full text]
  • Thermodynamics of Solar Energy Conversion in to Work
    Sri Lanka Journal of Physics, Vol. 9 (2008) 47-60 Institute of Physics - Sri Lanka Research Article Thermodynamic investigation of solar energy conversion into work W.T.T. Dayanga and K.A.I.L.W. Gamalath Department of Physics, University of Colombo, Colombo 03, Sri Lanka Abstract Using a simple thermodynamic upper bound efficiency model for the conversion of solar energy into work, the best material for a converter was obtained. Modifying the existing detailed terrestrial application model of direct solar radiation to include an atmospheric transmission coefficient with cloud factors and a maximum concentration ratio, the best shape for a solar concentrator was derived. Using a Carnot engine in detailed space application model, the best shape for the mirror of a concentrator was obtained. A new conversion model was introduced for a solar chimney power plant to obtain the efficiency of the power plant and power output. 1. INTRODUCTION A system that collects and converts solar energy in to mechanical or electrical power is important from various aspects. There are two major types of solar power systems at present, one using photovoltaic cells for direct conversion of solar radiation energy in to electrical energy in combination with electrochemical storage and the other based on thermodynamic cycles. The efficiency of a solar thermal power plant is significantly higher [1] compared to the maximum efficiency of twenty percent of a solar cell. Although the initial cost of a solar thermal power plant is very high, the running cost is lower compared to the other power plants. Therefore most countries tend to build solar thermal power plants.
    [Show full text]
  • Why Does the Wisconsin Boiler and Pressure Vessel Code, 636 41
    Why does the Wisconsin Boiler and Pressure Vessel Code, SPS 341, regulate air compressors? By Industry Services Division Boiler and Pressure Vessels Program Almost everyone forms a definite picture in their mind when they hear the term “air compressor.” They probably think of a steel tank of some shape and dimension, with an electric motor, and an air pump mounted on top of the tank. To better understand the requirements of the Wisconsin Boiler Code, SPS 341, pertaining to air compressors, we need to have some common terminology. If a person wanted to purchase an “air compressor” at a hardware or home supply store, they would certainly be offered the equipment described above, consisting of three separate mechanical devices; the motor, the pump, and the storage tank. First, there is an electric motor, used to provide power to the device that pumps air to high pressure. This pumping device is the only part of the unit that is properly called an "air compressor." The compressor delivers high-pressure air to the third and final part of the mechanical assembly, the air storage tank; commonly called a pressure vessel. Because the pressure vessel receives pressurized air, this is the only part of the device described above that is regulated SPS 341. SPS 341 regulates pressure vessels when the pressure vessel's volume capacity is 90 gallons (12 cubic feet) or larger, and the air pressure is 15 pounds per square inch or higher. A typical pressure vessel of this size would be 24 inches in diameter and 48 inches long. In industrial settings, it is common practice to mount very large air compressors in a separate location from the pressure vessels.
    [Show full text]
  • Performance Comparison Between an Absorption-Compression Hybrid Refrigeration System and a Double-Effect Absorption Refrigeration Sys-Tem
    Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com Procedia Engineering 00 (2017) 000–000 ScienceDirect www.elsevier.com/locate/procedia Procedia Engineering 205 (2017) 241–247 10th International Symposium on Heating, Ventilation and Air Conditioning, ISHVAC2017, 19- 22 October 2017, Jinan, China Performance Comparison between an Absorption-compression Hybrid Refrigeration System and a Double-effect Absorption Refrigeration Sys-tem Jian Wang, Xianting Li, Baolong Wang, Wei Wu, Pengyuan Song, Wenxing Shi* Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Department of Building Science, Tsinghua University, Haidian District, Beijing 100084, China Abstract Conventional absorption refrigeration systems (ARSs), which are mainly driven by heat, have a competitive primary energy efficiency (PEE) compared with chillers driven by electricity. In the typical ARS, a large quantity of high-temperature heat is supplied into the generator, while a substantial amount of low-temperature heat is rejected to the environment from the condenser, it’s a huge waste. In order to decrease the input heat for generator and enhance the performance of conventional ARS, a kind of absorption-compression hybrid refrigeration system recovering condensation heat for generation (RCHG-ARS) was ever proposed. In the present study, the models of both RCHG-ARS and double-effect absorption refrigeration system (DEARS) are established, and the effects of different parameters on them are simulated and compared with each other. As a conclusion, the PEE of RCHG-ARS can be 29.0% higher than that of DEARS, and RCHG-ARS has a wider working conditions than DEARS due to the existence of the compressor.
    [Show full text]
  • Bendix® Ba-922® Sae Universal Flange Air Compressor
    compressors BENDIX® BA-922® SAE UNIVERSAL FLANGE AIR COMPRESSOR High output compressed air generation for ultra demanding commercial & industrial applications. Experience Counts Ideal for niche industrial, agricultural, and For generations, Bendix Commercial Vehicle Systems (Bendix CVS) has petroleum applications, the universal flange been leading the way in air charging system experience and expertise. model . More fleets specify our hard-working products and systems than any other. Features an adapter mount to meet SAE J744 Bendix CVS continues its legacy of quality, reliability and durability with hydraulic pump, engine & motor mounting, a next generation high-performing, energy-saving compressor option – and drive dimensions standards; the Bendix® BA-922® SAE Universal Flange compressor. Can be mounted at several different angles An Ideal Solution For A Wide Range Of depending on physical constraints and application necessities; and Unique Applications Utilizing a standard SAE B Flange, and a 15-tooth BB spline for strength, Is driven by an engine PTO, hydraulic motor, the Bendix® BA-922® SAE compressor is designed to address a wide or electric motor. Option for belt drive as well. variety of commercial and industrial applications. Its clock-able front adapter allows the compressor to be easily mounted in several different positions depending on your requirement. Building On The Power Of The Bendix® BA-922® Compressor: High Air Delivery A dependable workhorse, the Bendix® BA-922® compressor provides maximum air delivery even at low speeds. Its high-output, two-cylinder design supplies 32 cfm (cubic feet per minute) displacement at 1,250 rpm (revolutions per minute). Power like this delivers the ability to recharge the system quickly and efficiently – even at low speeds – making it ideal for more demanding brake system applications.
    [Show full text]
  • Solar Thermal Energy
    22 Solar Thermal Energy Solar thermal energy is an application of solar energy that is very different from photovol- taics. In contrast to photovoltaics, where we used electrodynamics and solid state physics for explaining the underlying principles, solar thermal energy is mainly based on the laws of thermodynamics. In this chapter we give a brief introduction to that field. After intro- ducing some basics in Section 22.1, we will discuss Solar Thermal Heating in Section 22.2 and Concentrated Solar (electric) Power (CSP) in Section 22.3. 22.1 Solar thermal basics We start this section with the definition of heat, which sometimes also is called thermal energy . The molecules of a body with a temperature different from 0 K exhibit a disordered movement. The kinetic energy of this movement is called heat. The average of this kinetic energy is related linearly to the temperature of the body. 1 Usually, we denote heat with the symbol Q. As it is a form of energy, its unit is Joule (J). If two bodies with different temperatures are brought together, heat will flow from the hotter to the cooler body and as a result the cooler body will be heated. Dependent on its physical properties and temperature, this heat can be absorbed in the cooler body in two forms, sensible heat and latent heat. Sensible heat is that form of heat that results in changes in temperature. It is given as − Q = mC p(T2 T1), (22.1) where Q is the amount of heat that is absorbed by the body, m is its mass, Cp is its heat − capacity and (T2 T1) is the temperature difference.
    [Show full text]
  • Empirical Modelling of Einstein Absorption Refrigeration System
    Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 75, Issue 3 (2020) 54-62 Journal of Advanced Research in Fluid Mechanics and Thermal Sciences Journal homepage: www.akademiabaru.com/arfmts.html ISSN: 2289-7879 Empirical Modelling of Einstein Absorption Refrigeration Open Access System Keng Wai Chan1,*, Yi Leang Lim1 1 School of Mechanical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia ARTICLE INFO ABSTRACT Article history: A single pressure absorption refrigeration system was invented by Albert Einstein and Received 4 April 2020 Leo Szilard nearly ninety-year-old. The system is attractive as it has no mechanical Received in revised form 27 July 2020 moving parts and can be driven by heat alone. However, the related literature and Accepted 5 August 2020 work done on this refrigeration system is scarce. Previous researchers analysed the Available online 20 September 2020 refrigeration system theoretically, both the system pressure and component temperatures were fixed merely by assumption of ideal condition. These values somehow have never been verified by experimental result. In this paper, empirical models were proposed and developed to estimate the system pressure, the generator temperature and the partial pressure of butane in the evaporator. These values are important to predict the system operation and the evaporator temperature. The empirical models were verified by experimental results of five experimental settings where the power input to generator and bubble pump were varied. The error for the estimation of the system pressure, generator temperature and partial pressure of butane in evaporator are ranged 0.89-6.76%, 0.23-2.68% and 0.28-2.30%, respectively.
    [Show full text]
  • Teaching Psychrometry to Undergraduates
    AC 2007-195: TEACHING PSYCHROMETRY TO UNDERGRADUATES Michael Maixner, U.S. Air Force Academy James Baughn, University of California-Davis Michael Rex Maixner graduated with distinction from the U. S. Naval Academy, and served as a commissioned officer in the USN for 25 years; his first 12 years were spent as a shipboard officer, while his remaining service was spent strictly in engineering assignments. He received his Ocean Engineer and SMME degrees from MIT, and his Ph.D. in mechanical engineering from the Naval Postgraduate School. He served as an Instructor at the Naval Postgraduate School and as a Professor of Engineering at Maine Maritime Academy; he is currently a member of the Department of Engineering Mechanics at the U.S. Air Force Academy. James W. Baughn is a graduate of the University of California, Berkeley (B.S.) and of Stanford University (M.S. and PhD) in Mechanical Engineering. He spent eight years in the Aerospace Industry and served as a faculty member at the University of California, Davis from 1973 until his retirement in 2006. He is a Fellow of the American Society of Mechanical Engineering, a recipient of the UCDavis Academic Senate Distinguished Teaching Award and the author of numerous publications. He recently completed an assignment to the USAF Academy in Colorado Springs as the Distinguished Visiting Professor of Aeronautics for the 2004-2005 and 2005-2006 academic years. Page 12.1369.1 Page © American Society for Engineering Education, 2007 Teaching Psychrometry to Undergraduates by Michael R. Maixner United States Air Force Academy and James W. Baughn University of California at Davis Abstract A mutli-faceted approach (lecture, spreadsheet and laboratory) used to teach introductory psychrometric concepts and processes is reviewed.
    [Show full text]
  • Thermodynamics of Interacting Magnetic Nanoparticles
    This is a repository copy of Thermodynamics of interacting magnetic nanoparticles. White Rose Research Online URL for this paper: https://eprints.whiterose.ac.uk/168248/ Version: Accepted Version Article: Torche, P., Munoz-Menendez, C., Serantes, D. et al. (6 more authors) (2020) Thermodynamics of interacting magnetic nanoparticles. Physical Review B. 224429. ISSN 2469-9969 https://doi.org/10.1103/PhysRevB.101.224429 Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Thermodynamics of interacting magnetic nanoparticles P. Torche1, C. Munoz-Menendez2, D. Serantes2, D. Baldomir2, K. L. Livesey3, O. Chubykalo-Fesenko4, S. Ruta5, R. Chantrell5, and O. Hovorka1∗ 1School of Engineering and Physical Sciences, University of Southampton, Southampton SO16 7QF, UK 2Instituto de Investigaci´ons Tecnol´oxicas and Departamento de F´ısica Aplicada, Universidade de Santiago de Compostela,
    [Show full text]
  • Understanding Psychrometrics, Third Edition It’S Really a Mine of Information
    Gatley The Comprehensive Guide to Psychrometrics Understanding Psychrometrics serves as a lifetime reference manual and basic refresher course for those who use psychrometrics on a recurring basis and provides a four- to six-hour psychrometrics learning module to students; air- conditioning designers; agricultural, food process, and industrial process engineers; Understanding Psychrometrics meteorologists and others. Understanding Psychrometrics Third Edition New in the Third Edition • Revised chapters for wet-bulb temperature and relative humidity and a revised Appendix V that includes a summary of ASHRAE Research Project RP-1485. • New constants for the universal gas constant based on CODATA and a revised molar mass of dry air to account for the increase of CO2 in Earth’s atmosphere. • New IAPWS models for the calculation of water properties above and below freezing. • New tables based on the ASHRAE RP-1485 real moist-air numerical model using the ASHRAE LibHuAirProp add-ins for Excel®, MATLAB®, Mathcad®, and EES®. Includes Access to Bonus Materials and Sample Software • PDF files of 13 ultra-high-pressure and 12 existing ASHRAE psychrometric charts plus three new 0ºC to 400ºC charts. • A limited demonstration version of the ASHRAE LibHuAirProp add-in that allows users to duplicate portions of the real moist-air psychrometric tables in the ASHRAE Handbook—Fundamentals for both standard sea level atmospheric pressure and pressures from 5 to 10,000 kPa. • The hw.exe program from the second edition, included to enable users to compare the 2009 ASHRAE numerical model real moist-air psychrometric properties with the 1983 ASHRAE-Hyland-Wexler properties. Praise for Understanding Psychrometrics, Third Edition It’s really a mine of information.
    [Show full text]
  • Quantized Refrigerator for an Atomic Cloud
    Quantized refrigerator for an atomic cloud Wolfgang Niedenzu1, Igor Mazets2,3, Gershon Kurizki4, and Fred Jendrzejewski5 1Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21a, A-6020 Innsbruck, Austria 2Vienna Center for Quantum Science and Technology (VCQ), Atominstitut, TU Wien, 1020 Vienna, Austria 3Wolfgang Pauli Institute, c/o Fakultät für Mathematik, Universität Wien, 1090 Vienna, Austria 4Department of Chemical Physics, Weizmann Institute of Science, Rehovot 7610001, Israel 5Heidelberg University, Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, D-69120 Heidelberg, Germany June 24, 2019 We propose to implement a quantized ther- a) mal machine based on a mixture of two atomic species. One atomic species implements the working medium and the other implements two (cold and hot) baths. We show that such a setup can be employed for the refrigeration of a large bosonic cloud starting above and end- ing below the condensation threshold. We ana- lyze its operation in a regime conforming to the b) quantized Otto cycle and discuss the prospects for continuous-cycle operation, addressing the experimental as well as theoretical limitations. <latexit sha1_base64="xPORfqE4jiv0WYJsIrI5dlUB7fE=">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</latexit>Beyond
    [Show full text]
  • Factsheet Open-Flash-Economizer
    Better performance and efficiency from chillers Advantages and functions of an open flash economizer An open flash economizer can be used for both water-cooled and air-cooled compact machines, and also for split cooling systems. To optimise the cooling output, ENGIE Refrigeration equips all QUANTUM and QUANTUM-G models, as well as the SPECTRUM chiller, with open flash economizers. Effect Benefits for customer Explanation INCREASED • Lower investment costs per kilowatt of • Thermodynamic optimisation of the one-step COOLING OUTPUT cooling output (€/kW) cooling circuit through the integration of a mean pressure level with flash gas extraction, resulting in higher specific evaporation enthalpy SMALL • Higher cooling output per m² • The optimum integration of the open flash INSTALLATION AREA of installation area economizer means that the installation dimen- sions of the chiller remain the same INCREASE IN ENERGY • Lower operating costs at full load • Less technical work is required for the two-step EFFICIENCY (EER value compression process in comparison with the increases by up to 20 %) one-step compression process HIGHER • Lower operating costs at partial load • The benefits of the economizer affect all ESEER VALUE operating points OPTIMUM OPERATING • Maximum possible efficiency gain • Open flash economizer is inherently the BEHAVIOUR AT ALL under all operating conditions guaran- thermodynamically optimum solution LOAD LEVELS teed (e. g. changing cooling and heating media temperatures) • Flash gas in saturation state; extraction without superheating • Maximum possible efficiency gain with partial load guaranteed • No efficiency-lowering suction gas superheating, with superheating control required Increased cooling output log p Cooling process in log p h diagram with open flash econo- mizer (Eco) (green) and without economizer (grey).
    [Show full text]