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CONDENSING HEAT TRANSFER IN AN ADVANCED TWO-PHASE CLOSED thermosyphon

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Chinese Journal of Chemical Engineering 1996年第1期4卷 88-92页

作者：李修伦闻建平单岩昆黄鸿鼎天津大学化学工程系天津

1 INTRODUCTIONClosed thermosyphon has been developed to enhance heat transfer and recover wasteheat in various process industries [1,2].Stimulated by this success,a new type oftwo-phase closed thermosyphon was designed by inserting respectively two inner tubesinto the thermosyphon,one in the boiling section and the other in the condensing *** two-phase flow boiling heat transfer coefficient was calculated successfully onthe basis of Chen’s dual-mechanism [3].A boiling heat transfer model for thetwo-phase closed thermosyphon with an inner tube in the boiling section was pro-

关键词： two-phase closed thermosyphon heat transfer narrow annulus

Centrifuge model test on performance of thermosyphon cooled sandbags stabilizing warm oil pipeline buried in permafrost

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Research in Cold and Arid Regions 2021年第3期13卷 234-255页

作者： GuoYu Li HongYuan Jing Nikolay Volkov Wei Ma PengChao Chen State Key Laboratory of Frozen Soil Engineering(SKLFSE) Northwest Institute of Eco-Environment and Resources(NIEER)Chinese Academy of Sciences(CAS)LanzhouGansu 730000China Da Xing'anling Observation and Research Station of Frozen-ground Engineering and Environment NIEERCASJiagedaqiHeilongjiang 165000China PipeChina North Pipeline Company LangfangHebei 065000China GEOINGSERVICE LLP(Fugro Group) 29 Vernadskogo AvenueMoscowRussia

The thaw settlement of pipeline foundation soils in response to the operation of the first China-Russia Crude Oil Pipeline along the eastern flank of the northern Da Xing'anling Mountains in Northeast China was simulated in a physical model test(with a similitude ratio of 1/73) in a geotechnical centrifuge. Two pipes of a supported and an unsupported section were evaluated over a testing period for simulating 20 years of actual pipeline operation with seasonal cyclically changing oil and ambient temperatures. The results show that pipe settlement of the supported pipe was 45% of settlement of the unsupported pipe. Settlement for the unsupported section was approximately 35% of the thaw bulb depth below the initial pipe elevation, only 30% of that for the supported pipe due to the influence of the supports. The final thaw bulbs extended approximately 3.6 and 1.6 times of the pipe diameter below the unsupported and supported pipe bottom elevations, respectively. The sandbag supports kept frozen during the test period because of cooling effect of the thermosyphons. The maximum bending stress induced over the 20 m span length from bearing of the full cover over the pipe would be equivalent to40% specified minimum yield strength(SMYS). Potential buckling of the pipe should be considered as the ground *** study also offers important data for calibration and validation of numerical simulation models.

关键词： centrifuge test oil pipeline frost heave thermosyphon thaw settlement permafrost engineering

Boiling　Delay　Phenomenon　in　a　thermosyphon　Heat　Sink　and　Its　Effect　on　Device　Performance

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Journal of Thermal Science 1994年第3期3卷 183-186页

作者： WeilinHu YihuiZhou 等 DepartmentofEngineeringMechanics TsinghuaUniversityBeijing100084China DepartmentofEngineeringMechan

A new kind of thermosyphon heat sink has been studied and developed, its performance being *** was found that a remarkable boiling delay phenomenon occurs during its work. The phenomenon is described and explained and its effects on thermoresistance performance at both steady and transient states are discussed. The thermoresistance of this sink is found to be 0.029°C/W at air velocity 5m/*** heat sink will satisfy the needs of cooling rectifier diodes and thyristors of rated currents up to 1000 amperes.

关键词： heat sink thermosyphon boiling heat transfer

Numerical analysis on the thermal regimes of thermosyphon embankment in snowy permafrost area

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Research in Cold and Arid Regions 2017年第6期9卷 668-674页

作者： Yan Lu Xin Yi WenBing Yu WeiBo Liu State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China College of Civil Engineering Chongqing Jiaotong UniversityChongqing 400074China College of Civil Engineering Jiangxi University of Science and TechnologyGanzhouJiangxi 341000China University of Chinese Academy of Sciences Beijing 100049China

Snow covers the road embankments in winter in high latitude permafrost zones. The effect of snow cover on embankments was simulated based on field measurements of boundary conditions and initial ground temperature profile in Mohe,China. The effect of thermosyphons on the embankment warmed by snow cover was evaluated by numerical simulations as well. The results indicate that the difference of thermal regimes between non-thermosyphon and thermosyphon embankments reaches to 22 m in depth below the ground surface. It is much warmer in the non-thermosyphon embankment body in winter. Affected by the snow cover, heat flux gradually spreads into the deep ground of the subgrade over time. The permafrost table under the slope toe of a thermosyphon embankment is 1.2 m higher than that of a non-thermosyphon embankment in the 20 th year. In addition, the permafrost table at the slope toe of a thermosyphon embankment is 26 cm deeper over 20 years. These results indicate that thermosyphons can greatly weaken the warm effect of snow cover. However,thermosyphons cannot avoid the degradation of permafrost under the scenarios of snow cover. Therefore, composite measures need to be adopted to keep embankment stability in snowy permafrost zones.

关键词： snow cover permafrost embankment thaw settlement thermosyphon

NUMERICAL INVESTIGATION ON THE PHASE CHANGE OF WATER-SATURATED POROUS MEDIA WITH thermosyphon

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2000年第2期 12-18页

作者：吴存真潘阳秦悦慧

Numerical investigations were carried out to determine the coupled heat transfer of water saturated porous media with a two phase closed thermosyphon for soil freezing, and to examine the characteristics of the freezing heat transfer in the water saturated porous media. The whole control volume includes the thermosyphon and the porous media. The two dimensional governing equations for the water saturated porous media are used. The conjugation of heat transfer between the thermosyphon and porous media is reflected through thermal balance between the thermosyphon and the porous media. The finite difference method was used to solve the two\|dimensional governing equation for the water saturated porous media and the heat transfer characteristics of the thermosyphon, obtain the flow fields and the temperature distributions in the soil. This paper deals mainly with the effect of some factors (such as soil properties, climate and thermosyphon dimensions) on the heat transfer rate of the thermosyphon and the growth of the freezing front. The predictions of the present study agree well with the measured data.

关键词： thermosyphon water saturated porous soil freezing coupled heat transfer

What is Going on in a Critical thermosyphon?

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Tsinghua Science and Technology 2002年第2期7卷 109-115页

作者： E. Hahne, U. Gross , G. BarthauInstitut für Thermodynamik und Warmetechnik, Universitat Stuttgart, Pfaffenwaldring 6, D 70550 Stuttgart, Germany, E mail: pm@itw.uni stuttgart.de TU Bergakademie Freiberg, Institut für Technische Th Institut für Thcrmodynamik und Wärmetechnik Universität Stuttgart Pfaffenwaldring 6 D-70550 Stuttgart Germany TU Bergakademie Freiberg Insfitut für Technische Thermedynamik G.-Zeuner-Str. 7 D-09596 Freiberg Germany

Critically filled thermosyphons for heat transport differ in size and temperature distribution from critically filled testcells for property research. Consequently, the thermodynamic states within a thermosyphon are distributed more heterogeneously. In a glass thermosyphon, flows and phase distributions were observed. A break down of the heat transport mechanism was found as a consequence of flooding the cooling region with liquid. Observed and explained-by use of a density/pressure diagram-were the effects of heating, of pressure and of fluid quantity on the distribution of the phases, the appearance of pulsations and the propagation of a heat pulse near the critical state. 

关键词： critical state thermosyphon heat pipe opalesence

Thermal Modeling of thermosyphon Integrated Heat Sink for CPU Cooling

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Journal of Electronics Cooling and Thermal Control 2011年第2期1卷 15-21页

作者： A. Shanmuga Sundaram Anirudh Bhaskaran 不详

A thermal model has been developed to study the thermal behavior of thermosyphon integrated Heat Sink during CPU cooling. An Indirect cooling module has been experimentally studied and analyzed under steady state condition for both natural and forced convection. The thermal model is employed to determine the actual heat transfer and the effectiveness of the present model and compared it with the conventional cooling method and found that there is an appreciable improvement in the present model.

关键词： thermosyphon Heat Sink Effectiveness Conventional Cooling Method

A Loop thermosyphon Type Cooling System for High Heat Flux

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Journal of Electronics Cooling and Thermal Control 2014年第4期4卷 128-137页

作者： Jiwon Yeo Seiya Yamashita Mizuki Hayashida Shigeru Koyama Interdisciplinary Graduate School of Engineering Sciences Kyushu University Fukuoka Japan Faculty of Engineering Sciences Kyushu University Fukuoka Japan International Institute for Carbon-Neutral Energy Research (WPI-I2CNER) Kyushu University Fukuoka Japan

With rapid development of the semiconductor technology, more efficient cooling systems for electronic devices are needed. In this situation, in the present study, a loop thermosyphon type cooling system, which is composed mainly of a heating block, an evaporator and an air-cooled condenser, is investigated experimentally in order to evaluate the cooling performance. At first, it is examined that the optimum volume filling rate of this cooling system is approximately 40%. Next, four kinds of working fluids, R1234ze(E), R1234ze(Z), R134a and ethanol, are tested using a blasted heat transfer surface of the evaporator. In cases of R1234ze(E), R1234ze(Z), R134a and ethanol, the effective heat flux, at which the heating block surface temperature reaches 70°C, is 116 W/cm2, 106 W/cm2, 104 W/cm2 and 60 W/cm2, respectively. This result indicates that R1234ze(E) is the most suitable for the present cooling system. The minimum boiling thermal resistance of R1234ze(E) is 0.05 (cm2·K)/W around the effective heat flux of 100 W/cm2. Finally, four kinds of heat transfer surfaces of the evaporator, smooth, blasted, copper-plated and finned surfaces, are tested using R1234ze(E) as working fluid. The boiling thermal resistance of the blasted surface is the smallest among tested heat transfer surfaces up to 116 W/cm2 in effective heat flux. However, it increases drastically due to the appearance of dry-patch if the effective heat flux exceeds 116 W/cm2. On the other hand, in cases of copper-plated and finned surfaces, the dry-patch does not appear up to 150 W/cm2 in effective heat flux, and the boiling thermal resistances of those surfaces keep 0.1 (cm2·K)/W.

关键词： Cooling Boiling Loop thermosyphon Grobal Warming Potential Thermal Resistance

Effect of Non-Condensable Gas Leakage on Long Term Cooling Performance of Loop thermosyphon

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Journal of Electronics Cooling and Thermal Control 2013年第4期3卷 131-135页

作者： Hiroyuki Toyoda Yoshihiro Kondo Hitachi Research Laboratory Hitachi Ltd. 832-1 Horiguchi Hitachinaka Ibaraki Japan

We have developed a loop thermosyphon for cooling electronic devices. The cooling performance of a thermosyphon deteriorates with an increasing amount of non-condensable gas (NCG). Design of a thermosyphon must consider NCG to provide guaranteed performance for a long time. In this study, the heat transfer performance of a thermosyphon was measured while changing the amount of NCG. The resultant performances were expressed as approximations. These approximations enabled us to predict the total thermal resistance of the thermosyphon by the amount of NCG and input heating. Then, using the known leakage in the thermosyphon and the amount of dissolved NCG in the water, we can predict the amount of NCG and the total thermal resistance of the thermosyphon after ten years. Although there is a slight leakage in the thermosyphon, we are able to design a thermosyphon with a guaranteed level of cooling performance for a long time using the proposed design method.

关键词： thermosyphon Boiling Condensation Non-Condensable Gas Heat Transfer Performance CPU Cooling