Theoretical Analysis of the Pressure Oscillation Phenomena in Capillary Pumped Loop

INTRoDUCTIONCaPillaryPumpedLoop(CPL)isakindofheat-transferdevicewithhighefficiencyandhighreliabilityItcanmeettherequlrmellts0fthefuturelargespace-craftandisconsideredtobeoneofthemostpromisingthermal-Controlequlpmentinthefuturel1'2'3].Inthec0nventi0nalCPLanalysism0del,itiscon-sideredthattheheat-transfercapabilityofCPLisoalydetendnedbythecaPinarYf0rceofthewickintheeVaPor8tor.Thelo0PwinoperatenormallywhenPc@ishigherthantheresistanceofthewholel00pAPont,i.e.,Pc@>APont.However,sincethe…     

The Effect of Disturbance in the Evaporator on the Performance of Capillary Pumped Loop（CPL）

The disturbance, caused by the boiling phenomena in the inverted meniscus type evaporator, is of great importance in the normal operation of the CPL, especially when the heat load is low. By theoretical and experimental studies on this issue, it shows that the evaporator of the CPL operates in a mode of boiling in the wick. By solving a set of momentum equations, it concludes that, this kind of boiling phenomena in the wick cause no notable negative influence on the normal performance of the CPL, although there really exists some adverse influence during the CPL start-up. Additionally, the causes of the dry-out of the evaporator under low heat load are conducted in the paper. The conclusions are verified by subsequent experiments. More details about the experiments are also described in the paper.     

Experimental Studies on Heat Transfer in the Tip Gap of a Sectorial Turbine Cascade

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎｔｈｅＴｉｐＧａｐｏｆａＳｅｃｔｏｒｉａｌＴｕｒｂｉｎｅＣａｓｃａｄｅＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｉｅｓｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎｔｈｅＴｉｐＧａｐｏｆａＳｅｃｔｏｒｉａ...     

Experimental Study on Heat Transfer and Pressure Drop Characteristics of Four Types of Plate Fin－and－TUbe Heat Exchanger Surfaces

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎＨｅａｔＴｒａｎｓｆｅｒａｎｄＰｒｅｓｓｕｒｅＤｒｏｐＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＦｏｕｒＴｙｐｅｓｏｆＰｌａｔｅＦｉｎ－ａｎｄ－ＴＵｂｅＨｅａｔＥｘｃｈａｎｇｅｒＳｕｒｆａｃｅｓ￥Ｈ．Ｊ．Ｋａｎｇ；Ｗ．Ｌ...     

Influence of Tube‘s Diameter on Boling Heat Transfer Performance in Small Diameter Tubes

This paper reports the experiments of evaporation study in 6 mm inner copper diameter tubes using HFC-134a, HCFC-22 and CFC-12 as working fluid. The results show that the evaporation heat transfer coefficient increases with the decreasing of inner diameter of tubes. A new concept of non-dimensional tube diameter U is proposed in this paper for correction of the influence of the tube diameter on the evaporation heat transfer coefficient. And further, a convenient empirical correction method is presented.     

Experimental Research on Heat Transfer and Pressure Drop of Two Configurations of Pin Finned—Tubes in an In—line Array

ＥｘｐｅｒｉｍｅｎｔａｌＲｅｓｅａｒｃｈｏｎＨｅａｔＴｒａｎｓｆｅｒａｎｄＰｒｅｓｓｕｒｅＤｒｏｐｏｆＴｗｏＣｏｎｆｉｇｕｒａｔｉｏｎｓｏｆＰｉｎＦｉｎｎｅｄ－ＴｕｂｅｓｉｎＩｎ－ｌｉｎｅＡｒｒａｙＳｈｏｕＧｕａｎｇＹａｏ；ＤｅＳｈｕＺｈｕ（Ｄｅｐａ...     

Investigation on Operational Unsteady Characteristics of CPL：The Effects of Evaporator and Reservoir

INTRODUCTIONTwo-phaseCapillaryPUmpedLoopasanewthermalcontrolsysteminspacetechniqueshasmanyadVantages.Ittransportsrelativelylargeamountofheatforalongdistance.TheevaporatorandreservoirofCPLactasimportantpartsinthedevice,thesteadyandunsteadyoperationalperformancesofCPLstronglydependonbothofthemli'2].T'heCPLunsteadycharacteristicsconsistofsac-upandoperationalunsteadycharacteristics.WhenthemeasuredtemperatureoftypicalCPLpointdeviatesfromitsnormalvalueanddisplayscontinualoscillationchara…     

Experimental Study of Melting Heat Transfer in an Enclosure with Three Discrete Protruding Heat Sources

INTRoDUCTIONTheremovalofheatfr0melectroniccomp0nelltisessentialtothereliableoperationofelectronicequiP-mellt.TurnerandFlarkl1],Kelleheretal.l2]andotherinvestigatorsreportedtheirexperimentalresultsonairnaturalc0nvecti0nheattransferinrectangularenclDesurewithconcentratedheatsources,simulatingtheliaturalcoolingofchipsmouned0nprintedcircuitboard.Theirresultsshownthatthecoolingcapac-ity0fairnaturalc0nvecti0nisqultelimited.UsingsolidniquldphasechangetocoolelectroniccompDenelltsmaybeaprondsinga…     

Study on Characteristics of Steady Flow Condensation Heat Transfer in a Fube Under Zero—Gravitation

ＳｔｕｄｙｏｎＣｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆＳｔｅａｄｙＦｌｏｗＣｏｎｄｅｎｓａｔｉｏｎＨｅａｔＴｒａｎｓｆｅｒｉｎａＴｕｂｅｕｎｄｅｒＺｅｒｏ－ＧｒａｖｉｔａｔｉｏｎＱｎＷｅｉ（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈａｒｂｉ...     

Experimental and Numerical Investigation of Enhancement of Heat and Mass Transfer in Adsorbent Beds

ＥｘｐｅｒｉｍｅｎｔａｌａｎｄＮｕｍｅｒｉｃａｌＩｎｖｅｓｔｉｇａｔｉｏｎｏｆＥｎｈａｎｃｅｍｅｎｔｏｆＨｅａｔａｎｄＭａｓｓＴｒａｎｓｆｅｒｉｎＡｄｓｏｒｂｅｎｔＢｅｄｓＬｉｕＺｈｅｎｙａｎ；ＦｕＺｈｕｍａｎ；ＧｅＸｉｎｓｈｉ；ＳｕＹｕｅｈｏｎｇ；...     

Heat transfer with flow and phase change in an evaporator of miniature flat plate capillary pumped loop

An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop (CPL) evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick structure, liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall. The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The effect of heat conduction of metallic side wall on the performance of miniature flat plate CPL evaporator is analyzed, and side wall effect heat transfer limit is introduced to estimate the performance of evaporator. The shape and location of vapor-liquid interface inside the wick are calculated and the influences of applied heat flux, liquid subcooling, wick material and metallic wall material on the evaporator performance are investigated in detail. The numerical results obtained are useful for the miniature flat plate evaporator performance optimization and design of CPL.     

Study on heat transfer characteristics of reservoir embedded loop heat pipe (1st report,Influence of evaporator orientation against gravity and charged liquid weight on heat transfer characteristics)

High‐powered satellites need larger heat rejection areas. A deployable radiator is one of the key technologies for a high‐powered satellite bus. A Reservoir Embedded Loop Heat Pipe (RELHP) is a two‐phase heat transfer device that constitutes a deployable radiator. RELHP has an evaporator core which is used as a liquid reservoir to enhance operational reliability. This paper presents the heat transport characteristics of a RELHP under changing evaporator orientation against gravity and charged ammonia weight by experiment and calculation. Liquid slug position in the reservoir has a great influence on heat transport characteristics, caused by changing heat transfer coefficients between returned liquid into the evaporator and vapor in the reservoir. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(3): 143– 157, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20150     

Study on heat transfer characteristics of reservoir embedded loop heat pipe (Influence of condenser cooling method on heat transfer characteristics)

As heat generation in satellites increases, securing sufficient radiator panel area is an important problem. Deployable radiators, whose radiator panels are deployed post‐launch in space to increase the effective radiator panel area of the satellite, is becoming an important thermal control technology. A reservoir embedded loop heat pipe (RELHP) is applied to the deployable radiator for a thermal transport device. This paper presents the heat transport dynamic characteristics of a RELHP using a radiant cooling condenser and liquid forced convection cooling condenser by an experimental study. It was found that heat leak into the liquid line, flexible line, and reservoir increases the length of the sub‐cooling region in the condenser. In the case of the radiant cooling condenser, the sub‐cooling region length is shorter than that of a liquid forced convection cooling condenser. Furthermore, vapor temperature is mainly decided by the radiation capacity of the radiator panel, because liquid temperature returned into the evaporator rises with an increase in radiator panel temperature. In addition, time length from start‐up until steady state is greater than the liquid forced convection cooling condenser case, because the radiator panel has a large heat capacity. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20229     

Design of miniature loop heat pipe

In the present study, the loop heat pipe (LHP) was miniaturized for application to electronic cooling. According to the capillary limitation, the wick structure parameters that would affect the heat transfer capacity were analyzed theoretically. Among the various wick parameters, this study especially investigated the effect of wick thickness, which has rarely been mentioned in the literature. Here, various thicknesses were analyzed theoretically and then tested experimentally. The results showed that the temperature on the evaporator wall dropped with decreasing wick thickness. This effect would lead to the raising of heat transfer capacity and the descending of thermal resistance. According to the analysis and the practical demand for electronic cooling, a miniature LHP was fabricated with the evaporator outer diameter of 13 mm and the evaporator length of 50 mm. The testing results showed that, at the allowable working temperature of 80 °C, the maximum heat transfer capacity was up to 200 W and the thermal resistance was 0.17 °C/W. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(1): 42–52, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10133     

Experimental study on the operating characteristics of a capillary pumped loop with a flat evaporator

Recent advances in electronics technology have led to growing demand for highly efficient heat transfer devices with operating temperature controllability. Although capillary pumped loops are excellent candidates for this requirement and have been successful in various applications, their typical cylindrical evaporator shape has been a major drawback for applications to flat heat sources. Moreover, operating characteristics and the corresponding physical understanding of the capillary pumped loops are still uncertain, and lack of data for their operation makes their application unreliable. Thus, in this work, a capillary pumped loop with a flat evaporator was devised, and its operating characteristics were investigated.     

水平管降膜蒸发器传热传质实验研究

水平管降膜蒸发器因传质传热系数高而被广泛应用于淡化水处理中。搭建了水平管降膜蒸发传热实验台,通过对实验结果的归纳,得到了水平管降膜蒸发器的蒸发量随喷淋密度、蒸发温度、热通量的变化规律及热量利用率随蒸发温度的变化规律。结果表明,热通量范围不同时,蒸发量随喷淋密度的变化规律不同;蒸发量随热通量的增大而增大,随蒸发温度的增大而增大;热量利用率随蒸发温度的增大而增大。     

The Effect of Disturbance in the Evaporator on thePerformance of Capillary romped Loop (CPL)

INTRODUCTIOXWiththedevelOPmentofheatpipeteclmology,severalldndsofcapillarystrUctUrehasbeendeveloped,especiallytheadvertedMeniscusbeeEVaporator(IMTE)duetoitshigh-efficiencyandhighreliability['].Inthepast20years,withtheresearchesonCPL,moredetailsaboutthe~havebeenstUdied.NoW,nearlyallofthedesignedevaporatorforCPLis~.DL~stalevandA.FaghriconductedlotsofhelpfulstUdiesontheheattransfermechanismofthe~[v;Solov'evandKovalev'sexplorationonthissubjectwas-al-soinstrUchveinthisfield[3].Howev…     

Heat transfer characteristics of a reservoir embedded loop heat pipe (2nd report,Influence of noncondensable gas on heat transfer characteristics)

High‐powered satellites need larger heat rejection areas. A deployable radiator is one of the key technologies for a high‐powered satellite bus. A Reservoir Embedded Loop Heat Pipe (RELHP) is a two‐phase heat transfer device that constitutes the deployable radiator. RELHP has an evaporator core which is used as a liquid reservoir to enhance operational reliability. For use on satellites, RELHP is required to have a lifetime greater than 10 years. In the case of conventional heat pipes, it is generally known that noncondensable gas (NCG) has worse heat transport characteristics. On the other hand, the influence of NCG on a RELHP is not still obvious. This paper presents the heat transport characteristics of RELHP for the case of changing NCG volume by experiment and calculation. It was found that NCG increases temperature rise at the evaporator. NCG volume in a RELHP has a great influence on heat transport characteristics due to the reservoir pressure increase caused by NCG. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 459–473, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20181