DOCSLIB.ORG

Cooling Systems in Automobiles & Cars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cooling Systems in Automobiles & Cars International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-2, Issue-4, April 2013 Cooling Systems in Automobiles & Cars Gogineni. Prudhvi, Gada.Vinay, G.Suresh Babu Abstract: Most internal combustion engines are fluid cooled What the cooling system does for an engine. using either air (a gaseous fluid) or a liquid coolant run through a heat exchanger (radiator) cooled by air. 1. Although gasoline engines have improved a lot, they In air cooling system, heat is carried away by the air flowing are still not very efficient at turning chemical energy over and around the cylinder. Here fins are cast on the cylinder into mechanical power. head and cylinder barrel which provide additional conductive 2. Most of the energy in the gasoline (perhaps 70%) is and radiating surface. In water-cooling system of cooling engines, the cylinder walls and heads are provided with jacket converted into heat, and it is the job of the cooling through which the cooling liquid can circulate. system to take care of that heat. In fact, the cooling An internal combustion engine produces power byburning fuel system on a car driving down the freeway dissipates within the cylinders; therefore, it is oftenreferred to as a "heat enough heat to heat two average-sized houses! engine." However, only about25% of the heat is converted to 3. The primary job of the cooling system is to keep the useful power. Whathappens to the remaining 75 percent? Thirty engine from overheating by transferring this heat to the to thirtyfive percent of the heat produced in the air, but the cooling system also has several other combustionchambers by the burning fuel are dissipated by important jobs. thecooling system along with the lubrication and 4. The engine in your car runs best at a fairly high fuelsystems. Forty to forty- five percent of the heatproduced passes out with the exhaust gases. If this heatwere not removed temperature. quickly, overheating and extensive 5. When the engine is cold, components wear out faster, damage would result. Valves would burn and warp,lubricating and the engine is less efficient and emits more oil would break down, pistons and bearingwould overheat and pollution. seize, and the engine would soonstop.The necessity for cooling 6. So another important job of the cooling system is to may be emphasized byconsidering the total heat developed by an allow the engine to heat up as quickly as possible, and ordinary six-cylinder engine. then to keep the engine at a constant temperature. I. INTRODUCTION What is a Cooling System? We know that in case of Internal Combustion engines, A typical 4 cylinder vehicle cruising along the highway at combustion of air and fuel takes place inside the engine around 50 miles per hour, will produce 4000 controlled cylinder and hot gases are generated. The temperature of explosions per minute inside the engine as the spark plugs gases will be around 2300-2500°C. This is a very high ignite the fuel in each cylinder to propel the vehicle down temperature and may result into burning of oil film between the road. Obviously, these explosions produce an enormous the moving parts and may result into seizing or welding of amount of heat and, if not controlled, will destroy an engine the same. in a matter of minutes. Controlling these high temperatures So, this temperature must be reduced to about 150-200°C at is the job of the cooling system. which the engine will work most efficiently. Too much The modern cooling system has not changed much from the cooling is also not desirable since it reduces the thermal cooling systems in the model T back in the '20s. Oh sure, it efficiency. So, the object of cooling system is to keep the has become infinitely more reliable and efficient at doing it's engine running at its most efficient operating temperature. job, but the basic cooling system still consists of liquid It is to be noted that the engine is quite inefficient when it is coolant being circulated through the engine, then out to the cold and hence the cooling system is designed in such a way radiator to be cooled by the air stream coming through the that it prevents cooling when the engine is warming up and front grill of the vehicle. till it attains to maximum efficient operating temperature, Today's cooling system must maintain the engine at a then it starts cooling. constant temperature whether the outside air temperature is It is also to be noted that : 110 degrees Fahrenheit or 10 below zero. If the engine (a) About 20-25% of total heat generated is used for temperature is too low, fuel economy will suffer and producing brake power (useful work). emissions will rise. If the temperature is allowed to get too (b) Cooling system is designed to remove 30-35% of total hot for too long, the engine will self destruct. heat. (c) Remaining heat is lost in friction and carried away by How Does a Cooling System Work? exhaust gases. Actually, there are two types of cooling systems found on motor vehicles: Liquid cooled and Air cooled. Air cooled engines are found on a few older cars, like the original Volkswagen Beetle, the Chevrolet Corvair and a few others. Many modern motorcycles still use air cooling, but for the most part, automobiles and trucks use liquid cooled systems and that is what this article will concentrate on. Manuscript received April, 2013. The cooling system is made up of the passages inside the Gogineni. Prudhvi, KL University, Guntur (A.P.), India Gada.Vinay, KL University, Guntur (A.P.), India engine block and heads, a water pump to circulate the G.Suresh Babu, KL University, Guntur (A.P.), India coolant, a thermostat to control the temperature of the 688 Cooling Systems in Automobiles & Cars coolant, a radiator to cool the coolant, a radiator cap to Antifreeze control the pressure in the system, and some plumbing The coolant that courses through the engine and associated consisting of interconnecting hoses to transfer the coolant plumbing must be able to withstand temperatures well from the engine to radiator and below zero without freezing. It must also be able to handle also to the car's heater system where hot coolant is used to engine temperatures in excess of 250 degrees without warm up the vehicle's interior on a cold day. boiling. A tall order for any fluid, but that is not all. The A cooling system works by sending a liquid coolant through fluid must also contain rust inhibiters and a lubricant. passages in the engine block and heads. As the coolant The coolant in today's vehicles is a mixture of ethylene flows through these passages, it picks up heat from the glycol (antifreeze) and water. The recommended ratio is engine. The heated fluid then makes its way through a fifty-fifty. In other words, one part antifreeze and one part rubber hose to the radiator in the front of the car. As it water. This is the minimum recommended for use in flows through the thin tubes in the radiator, the hot liquid is automobile engines. Less antifreeze and the boiling point cooled by the air stream entering the engine compartment would be too low. In certain climates where the from the grill in front of the car. Once the fluid is cooled, it temperatures can go well below zero, it is permissible to returns to the engine to absorb more heat. The water pump have as much as 75% antifreeze and 25% water, but no has the job of keeping the fluid moving through this system more than that. Pure antifreeze will not work properly and of plumbing and hidden passages. can cause a boil over. II. TYPES OF COOLING SYSTEMS There are mainly two types of cooling systems : (a) Air cooled system, and (b) Water cooled system. Introduction to air cooling: Turbo cooling have been adopted for IC-engines at least since 1975 by I Kalmar and J Antal for Nox reduction in CI- engines. Engineers from SWRI contributed in the same subject between 1990-1991 with adress to M Shahed and RH Thring in the ”Clean Diesel Project” Volvo Truck also performed a MSc thesis work carried out by Jan Wiman in 1991. A thermostat is placed between the engine and the radiator to make sure that the coolant stays above a certain preset III. AIR COOLING SYSTEM temperature. If the coolant temperature falls below this Air cooled system is generally used in small engines say up temperature, the thermostat blocks the coolant flow to the to 15-20 kW and in aero plane engines. In this system fins or radiator, forcing the fluid instead through a bypass directly extended surfaces are provided on the cylinder walls, back to the engine. The coolant will continue to circulate cylinder head, etc. Heat generated due to combustion in the like this until it reaches the design temperature, at which engine cylinder will be conducted to the fins and when the point, the thermostat will open a valve and allow the coolant air flows over the fins, heat will be dissipated to air. back through the radiator. The amount of heat dissipated to air depends upon : Circulation (a) Amount of air flowing through the fins.b) Fin surface The coolant follows a path that takes it from the water area. pump, through passages inside the engine block where it (c) Thermal conductivity of metal used for fins. collects the heat produced by the cylinders. It then flows up to the cylinder head (or heads in a V type engine) where it Advantages of Air Cooled System collects more heat from the combustion chambers.
Load more

Recommended publications
  • Avionics Thermal Management of Airborne Electronic Equipment, 50 Years Later
    FALL 2017 electronics-cooling.com THERMAL LIVE 2017 TECHNICAL PROGRAM Avionics Thermal Management of Advances in Vapor Compression Airborne Electronic Electronics Cooling Equipment, 50 Years Later Thermal Management Considerations in High Power Coaxial Attenuators and Terminations Thermal Management of Onboard Charger in E-Vehicles Reliability of Nano-sintered Silver Die Attach Materials ESTIMATING INTERNAL AIR ThermalRESEARCH Energy Harvesting ROUNDUP: with COOLING TEMPERATURE OCTOBERNext Generation 2017 CoolingEDITION for REDUCTION IN A CLOSED BOX Automotive Electronics UTILIZING THERMOELECTRICALLY ENHANCED HEAT REJECTION Application of Metallic TIMs for Harsh Environments and Non-flat Surfaces ONLINE EVENT October 24 - 25, 2017 The Largest Single Thermal Management Event of The Year - Anywhere. Thermal Live™ is a new concept in education and networking in thermal management - a FREE 2-day online event for electronics and mechanical engineers to learn the latest in thermal management techniques and topics. Produced by Electronics Cooling® magazine, and launched in October 2015 for the first time, Thermal Live™ features webinars, roundtables, whitepapers, and videos... and there is no cost to attend. For more information about Technical Programs, Thermal Management Resources, Sponsors & Presenters please visit: thermal.live Presented by CONTENTS www.electronics-cooling.com 2 EDITORIAL PUBLISHED BY In the End, Entropy Always Wins… But Not Yet! ITEM Media 1000 Germantown Pike, F-2 Jean-Jacques (JJ) DeLisle Plymouth Meeting, PA 19462 USA
    [Show full text]
  • Valve Solutions for Pulp & Paper Applications 97.01-01
    BULLETIN 97.01-01 MAY 2021 VALVE SOLUTIONS FOR THE PULP & PAPER INDUSTRY The DeZURIK Difference Throughout our 250 years of combined history, DeZURIK, APCO, and HILTON have been recognized worldwide for collaborating with customers to design and engineer valves that provide superior performance and value. Each company was founded by an innovator who set out to solve a customer’s problem application. DeZURIK’s founder, Matt DeZURIK, started designing products for the Sartell Paper Mill in 1925 that included knot boring machines, consistency transmitters and shower pipes. When he noticed that valves weren’t able to seal due to pitch build-up, he invented the first Eccentric Plug Valve – a design still in use today, dutifully solving sealing problems worldwide. Today, the DeZURIK, APCO, and HILTON brands continue the tradition of partnering with our customers in the Pulp & Paper industry to provide the newest innovations in control, gate, plug, butterfly, automatic air and check DeZURIK’s original Eccentric Plug valves. Our vision is to deliver exceptional value to our customers Valve, developed in 1925 for the Sartell Paper Mill to solve a problem by applying our valve and problem-solving expertise to improve their with pitch build-up. operational performance. Full-Featured Valves for Today Applications DeZURIK recognizes the importance that control valves can play in process control performance and productivity. That’s why DeZURIK is dedicated to control valve testing. Regulating critical aspects of control valve performance such as accuracy, hysteresis, deadband and response time ensures that DeZURIK control valves provide optimum performance and help reduce costs. DeZURIK Knife Gate Valves and V-Port Ball Valves are widely used in pulping and stock prep operations throughout the mill.
    [Show full text]
  • Development of a Throttleless Natural Gas Engine
    February 2002 • NREL/SR-540-31141 Development of a Throttleless Natural Gas Engine Final Report John T. Kubesh Southwest Research Institute San Antonio, Texas National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 NREL is a U.S. Department of Energy Laboratory Operated by Midwest Research Institute ••• Battelle ••• Bechtel Contract No. DE-AC36-99-GO10337 February 2002 • NREL/SR-540-31141 Development of a Throttleless Natural Gas Engine Final Report John T. Kubesh Southwest Research Institute San Antonio, Texas NREL Technical Monitor: Mike Frailey Prepared under Subcontract No. ZCI-9-29065-01 National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 NREL is a U.S. Department of Energy Laboratory Operated by Midwest Research Institute ••• Battelle ••• Bechtel Contract No. DE-AC36-99-GO10337 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at http://www.osti.gov/bridge Available for a processing fee to U.S.
    [Show full text]
  • ENGINE COOLING and VEHICLE AIR CONDITIONING AGRICULTURAL and CONSTRUCTION VEHICLES What Is Thermal Management?
    ENGINE COOLING AND VEHICLE AIR CONDITIONING AGRICULTURAL AND CONSTRUCTION VEHICLES What is thermal management? Modern thermal management encompasses the areas of engine cooling and vehicle air conditioning. In addition to ensuring an optimum engine temperature in all operating states, the main tasks include heating and cooling of the vehicle cabin. However, these two areas should not be considered in isolation. One unit is often formed from components of these two assemblies which influence one another reciprocally. All components used must therefore be as compatible as possible to ensure effective and efficient thermal management. In this brochure, we would like to present you with an overview of our modern air-conditioning systems and also the technology behind them. We not only present the principle of operation, we also examine causes of failure, diagnosis options and special features. Disclaimer/Picture credits The publisher has compiled the information provided in this training document based on the information published by the automobile manufacturers and importers. Great care has been taken to ensure the accuracy of the information. However, the publisher cannot be held liable for mistakes and any consequences thereof. This applies both to the use of data and information which prove to be wrong or have been presented in an incorrect manner and to errors which have occurred unintentionally during the compilation of data. Without prejudice to the above, the publisher assumes no liability for any kind of loss with regard to profits, goodwill or any other loss, including economic loss. The publisher cannot be held liable for any damage or interruption of operations resulting from the non-observance of the training document and the special safety notes.
    [Show full text]
  • Using Radiators with Wetback Fires the Joy of Fire with the Comfort of Central Heating
    using radiators with wetback fires The joy of fire with the comfort of central heating. Heating Radiators with Fire Log burners are commonly available with a wetback system that heats • Heat more of your home with a hot water cylinder. It’s possible to extend the functionality of the your fire wetback by using radiators to spread the heat to other parts of the house. • Radiators available in a This means you can get the pleasure of watching a fire burn in your living variety of styles and endless room while the rest of the home is brought to a comfortable temperature colour options by the radiators. • Using a cheap and reliable People often try to move the hot air from a fire into other parts of the source of firewood means no house with duct work. Moving heat with water is so much more effective additional fuel costs as water transports energy four times better than air. The number of radiators you can heat depends on the heat output of the wetback and the rating of the radiators. A typical wetback only provides 2 to 4kW of heat as this is all that is needed to heat a hot water cylinder if the fire is on for five to ten hours per day. In order to heat a central heating system, a wetback with a higher output is often required. There are fires that have larger wetbacks (up to 15kW) and put out more heat to the wetback, enabling more radiators to be connected. How It Works While the fire is burning, the heat from the combustion process heats water jackets installed within the firebox.
    [Show full text]
  • Comparison of a Novel Polymeric Hollow Fiber Heat Exchanger and a Commercially Available Metal Automotive Radiator
    polymers Article Comparison of a Novel Polymeric Hollow Fiber Heat Exchanger and a Commercially Available Metal Automotive Radiator Tereza Kroulíková 1,* , Tereza K ˚udelová 1 , Erik Bartuli 1 , Jan Vanˇcura 2 and Ilya Astrouski 1 1 Heat Transfer and Fluid Flow Laboratory, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic; [email protected] (T.K.); [email protected] (E.B.); [email protected] (I.A.) 2 Institute of Automotive Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic; [email protected] * Correspondence: [email protected] Abstract: A novel heat exchanger for automotive applications developed by the Heat Transfer and Fluid Flow Laboratory at the Brno University of Technology, Czech Republic, is compared with a conventional commercially available metal radiator. The heat transfer surface of this heat exchanger is composed of polymeric hollow fibers made from polyamide 612 by DuPont (Zytel LC6159). The cross-section of the polymeric radiator is identical to the aluminum radiator (louvered fins on flat tubes) in a Skoda Octavia and measures 720 × 480 mm. The goal of the study is to compare the functionality and performance parameters of both radiators based on the results of tests in a calibrated air wind tunnel. During testing, both heat exchangers were tested in conventional conditions used for car radiators with different air flow and coolant (50% ethylene glycol) rates. The polymeric hollow fiber heat exchanger demonstrated about 20% higher thermal performance for the same air flow. The Citation: Kroulíková, T.; K ˚udelová, T.; Bartuli, E.; Vanˇcura,J.; Astrouski, I.
    [Show full text]
  • LIO-360-B1G6 Engine Maintenance Manual Lycoming Part Number: MM-LIO-360-B1G6
    Engine Maintenance Manual (Principal Manual) LIO-360-B1G6 Engine September 2017 Part No. MM-LIO-360-B1G6 © 2017 Avco Corporation. All Rights Reserved. LIO-360-B1G6 Engine Maintenance Manual Lycoming Part Number: MM-LIO-360-B1G6 Contact Us: Mailing Address: Lycoming Engines 652 Oliver Street Williamsport, PA 17701 USA Phone: U.S. and Canada Toll Free: +1 (800) 258-3279 Factory Direct: +1 (570) 323-6181 Technical Support Hotline • +1 (877) 839-7878 (Toll Free) • +1 (570) 327-7222 Lycoming’s regular business hours are Monday through Friday from 8:00AM through 5:00PM Eastern Time (-5 GMT). Visit us Online: www.Lycoming.com LIO-360-B1G6 Engine Maintenance Manual RECORD OF REVISIONS Revision Revised Revision Date By Revision Description Original Original Release of Maintenance Manual - Part No. MM-LIO-360-B1G6 © 2017 Avco Corporation. All Rights Reserved Record of Revisions September 2017 Page i LIO-360-B1G6 Engine Maintenance Manual This page intentionally left blank. Record of Revisions © 2017 Avco Corporation. All Rights Reserved Page ii September 2017 LIO-360-B1G6 Engine Maintenance Manual SERVICE DOCUMENT LIST NOTICE: The following is a list of service documents referenced in or incorporated into the information in this manual. Always refer to the latest revision of any service document (including any supplements) for changes or additional information. Number Incorporation Subject Date S.B. 201 09/17 Inspection of Crankshaft Flange S.B. 240 09/17 Mandatory Parts Replacement at Overhaul and During Repair or Maintenance S.B. 342 09/17 Fuel Line (Stainless Steel Tube Assy.) and Support Clamp Inspection and Installation S.B.
    [Show full text]
  • Crankshaft Kit Catalog • 2013 Engine Vin Code / Liters Cyl
    Distributed by: Sterling Bearing: Kansas City, Minneapolis, Worcester 800/821-5148 www.sbi.qwik-order.com Crankshaft Kit Catalog • 2013 Engine Vin Code / Liters Cyl. Years Description Forging numbers Wt. Part # CI / CC Engine Model ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA • ACURA ACURA Integra. Flywheel flange has six bolt holes. Neck 1.6 4 86-87 D16A1 36 80013 diameter is .865". Integra. Flywheel flange has six bolt holes. Neck 1590cc 1.6 4 88-89 D16A1 32 80014 diameter is .944". Integra. Flywheel flange has eight bolt holes. Neck 1.6 4 88-89 D16A1 36 80015 diameter is 1.102". 1678cc 1.7 4 92-93 B17A1 DOHC, Integra GS-R, Vigor, V-TEC engine. 38 80016 DOHC. Integra GS-R 94-01, R Type 97-01, V-TEC 1797cc 1.8 4 94-01 B18C1 B18C5 38 80017 engine. 1834cc 1.8 4 90-01 B18A1 B18B1 Integra - Except GS-R and V-TEC. 36 80018 2156cc 2.2 4 97 F22B1 CL - Crankshaft has a 16mm bolt hole in neck. 38 80019 2.5 5 92-94 G25A1 Vigor. 38 80020 2456cc 2.5 5 95-98 G25A4 38 80020 For engines with housing bore of 2.7165" and 14mm 2675cc 2.7 V6 87-90 C27A1 35 80021 bolt hole in neck. Legend. Isuzu engine used in SLX. Remove reluctor ring from 3165cc 3.2 V6 96-97 6VD1 37 92031 old unit and install on new unit 3.2 V6 91-95 C32A1 Legend.
    [Show full text]
  • Marine Safety Investigation Report 170
    MARINE SAFETY INVESTIGATION REPORT 170 Independent investigation into the disabling of the Antigua and Barbuda flag general cargo vessel ANL Purpose in the Coral Sea on 6 August 2001 AUSTRALIAN GOVERNMENT — DEPARTMENT OF TRANSPORT AND REGIONAL SERVICES Department of Transport and Regional Services Australian Transport Safety Bureau Navigation Act 1912 Navigation (Marine Casualty) Regulations investigation into the disabling of the Antigua and Barbuda flag general cargo vessel ANL Purpose in the Coral Sea on 6 August 2001 Report No 170 August 2003 ISSN 1447-087X ISBN1 877071 35 8 Readers are advised that the Australian Transport Safety Bureau investigates for the sole purpose of enhancing transport safety. Consequently, Bureau reports are confined to matters of safety significance and may be misleading if used for other purposes. Investigations commenced on or before 30 June 2003, including the publication of reports as a result of those investigations, are conducted in accordance with the Navigation (Marine Casualty) Regulations 1990, made pursuant to subsections 425(1)(ea) and 425 (1AAA) of the Navigation Act 1912. Investigations commenced on or after 1 July 2003, including the publication of reports as a result of those investigations, are authorised by the Executive Director of the Bureau in accordance with the Transport Safety Investigation Act 2003 (TSI Act). Reports released under the TSI Act are not admissible as evidence in any civil or criminal proceedings. It is ATSB policy to publish such reports in full as an educational tool to increase awareness of the causes of marine incident reports so as to improve safety at sea and enhance the protection of the marine environment, To increase the value of the safety material presented in this report, readers are encouraged to copy or reprint the material, in part or in whole, for further distribution, but should acknowledge the source.
    [Show full text]
  • Small Block Chevy Compatible Head Instructions
    301 Maple Ave. • P.O. Box 1347 Mena, AR • 71953 (479) 394-1075 • Fax: (479) 394-1996 www.brodix.com GENERAL INSTRUCTIONS FOR SMALL BLOCK CHEVY COMPATIBLE HEADS AND Important Notice This catalog has been completed using our best efforts.ATTENTION: We assume no liability for errors contained herein. Our website is LS COMPATIBLE HEADS updated on VALVEa regular basisSPRING and can WARNING be used to supplement FOR ALLthe information PACKAGES contained herein. On allIt iscomplete the responsibility packages, of the installer it is very to ensure possible that all that of the your products valve are springs correct beforeare not installation. correct Properfor your assembly camshaft. always All 301 Maple Ave. • P.O. Box 1347 Use Loc-Tite “271” sealant on rocker stud threads. Torque requires that the installer measure all tolerances for proper clearance. We assume no liability for any errors made in product to 40-45 ft-lb. valve springs should be checked for compatibilityselection to or your installation camshaft. Severe wear of valve train components Mena, AR • 71953 and severe engine damage could result from failure to do this. Check spring requirements before heads (479) 394-1075 • Fax: (479) 394-1996 are installed on the engine. BRODIX requires you to supply the valve springs for any engine that has a flat Do not cut spring pockets any larger or deeper than stan- www.brodix.com dard size before consulting with a BRODIX technician. tappet camshaft with over .615 valve lift. WARRANTY DISCLAIMER: WARNING! Fel-Pro or Cometic head gaskets are recommended. No warranties of any nature (expressed, implied, fitness of usage or merchantability) are given on these Always check for gasket overlap into chambers.
    [Show full text]
  • Heat Transfer and Cooling Techniques at Low Temperature
    Heat Transfer and Cooling Techniques at Low Temperature B. Baudouy1 CEA Saclay, France Abstract The first part of this chapter gives an introduction to heat transfer and cooling techniques at low temperature. We review the fundamental laws of heat transfer (conduction, convection and radiation) and give useful data specific to cryogenic conditions (thermal contact resistance, total emissivity of materials and heat transfer correlation in forced or boiling flow for example) used in the design of cooling systems. In the second part, we review the main cooling techniques at low temperature, with or without cryogen, from the simplest ones (bath cooling) to the ones involving the use of cryocoolers without forgetting the cooling flow techniques. Keywords: heat-transfer, cooling techniques, low-temperature, cryogen. 1 Introduction Maintaining a system at a temperature much lower than room temperature implies that the design of your cooling system must ensure its thermal stability in the steady-state regime; that is, the temperature of your system must remain constant in the nominal working condition. It also requires a certain level of thermal protection against transient events; that is, your temperature system must stay below a certain value to avoid problematic situations such as extra mechanical constraints due to the thermal expansion of materials with temperature. The ultimate goal is to minimize the heat load from the surroundings and to maximize the heat transfer with a cooling device. To be able to achieve this objective, identification of the different heat loads on the system is required, as well as knowledge of the fundamental laws of heat transfer, the thermo-physical properties of materials and fluids such as the density (kg·m–3) and heat capacity (J·kg–1·K –1), and thermal conductivity (W·m–1·K–1) and the cooling techniques such as conduction, radiation or forced flow based techniques.
    [Show full text]
  • HEAT PIPE COOLING of TURBOSHAFT ENGINES William G
    E AMEICA SOCIEY O MECAICA EGIEES -G-220 y t 345 E. 47th St., New York, N.Y. 10017 C e Sociey sa o e esosie o saemes o oiios aace i ^7 papers or discussion at meetings of the Society or of its Divisions or Sections, m ® o ie i is uicaios iscussio is ie oy i e ae is u- ise i a ASME oua aes ae aaiae om ASME o mos ae e meeig ie i USA Copyright © 1993 by ASME EA IE COOIG O UOSA EGIES Downloaded from http://asmedigitalcollection.asme.org/GT/proceedings-pdf/GT1993/78903/V03AT15A071/2403426/v03at15a071-93-gt-220.pdf by guest on 27 September 2021 William G. Anderson Sandra Hoff Dave Winstanley Thermacore, Inc. Power Systems Division John Phillips Lancaster, PA U.S. Army Scott DelPorte Fort Eustis, Virginia Garrett Engine Division Allied Signal Aerospace Co. Phoenix, Arizona ASAC an effective thermal conductivity that is hundreds of times larger Reduction in turbine engine cooling flows is required to meet than copper. Because of their large effective thermal the IHPTET Phase II engine performance levels. Heat pipes, conductivity, most heat pipes are essentially isothermal, with which are devices with very high thermal conductance, can help temperature differences between the evaporator and condenser reduce the required cooling air. A survey was conducted to ends on the order of a degree celsius. The only significant identify potential applications for heat pipes in turboshaft engines. temperature drop is caused by heat conduction through the heat The applications for heat pipe cooling of turbine engine pipe envelope and wick.
    [Show full text]