Transient two-phase heat transfer in a capillary-pumped-loop reservoir for spacecraft thermal management

1993 ◽  
Author(s):  
Wei Shyy ◽  
William K. Gingrich ◽  
William J. Krotiuk ◽  
Joseph E. Fredley
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Capillary Pumped Loop ◽  
Two Phase ◽  
Two Phase Heat Transfer

Experiment of a Novel Capillary-Pumped Loop With a Semi-Arc Porous Evaporator in 1U Simulation Cabinet

2005 ◽  
Author(s):  
Hung-Wen Lin ◽  
Ming-Chieh Wu ◽  
Wei-Keng Lin
Keyword(s):  
Thermal Management ◽  
High Efficiency ◽  
Size Range ◽  
Working Fluid ◽  
Power Electronic ◽  
Capillary Pumped Loop ◽  
Two Phase ◽  
Scale Down ◽  
Two Phase Heat Transfer ◽  
Transfer Device

The CPL is a high efficiency two-phase heat transfer device using the phase change of working fluid to transport heat from evaporator to condenser; it is a cyclic circulation pumped by capillary force. Since CPL does not need any other mechanical force such as pump, it might be used to do the thermal management of high power electronic component on spacecraft. This study presents a novel CPL with a semi-arc porous evaporator in 1U server on the ground with a horizontal position and scale down the whole device to the miniature size (range from mm to cm). This miniature-CPL is made of aluminum with the shape of evaporator and the porous structure using a semi-arc instead of square and cylinder structure. Testing results show that the miniature-CPL could remove heat 45W in steady state and keep the heat source temperature about 73°C.

Steady State Thermal Behaviour of Ceramic Wick Structure for Application in Two Phase Heat Transfer Devices

2014 ◽  
Vol 1082 ◽  
pp. 302-308
Author(s):  
Lucas Freitas Berti ◽  
Paulo Henrique Dias dos Santos ◽  
Carlos Renato Rambo ◽  
Dachamir Hotza ◽  
Edson Bazzo
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Thermal Behaviour ◽  
Capillary Pumped Loop ◽  
Two Phase ◽  
Evaporator Temperature ◽  
Steady State Condition ◽  
Wick Structure ◽  
Permeability Constants ◽  
Two Phase Heat Transfer

This work reports on results from two phase heat transfer devices assembled with ceramic capillary structure. It is firstly presented the manufacturing of the ceramic wick structures and afterwards the characterization of the morphological-and fluid-dynamical properties of these ceramic wick structures. As closing results, it is presented the thermal behaviour of two different two phase heat transfer devices, i.e. a Capillary Pumped Loop and a Loop Heat Pipe. The properties of the ceramic wick structure are within the desirable range for a correct functioning of these devices, e.g. porosity, pore size and permeability constants ranging from 40 to 60%, from 5 to 30μm and from 10-10 to 10-13m2, respectively. The thermal behaviour tests of the heat transfer devices used power heat load input in range from 10 to 20W and for all devices the evaporator temperature reached steady state condition. Thus, as a result, it can be claimed these ceramic wick structures as successful alternative for assembling capillary evaporator of CPL and LHP.

Mathematical Modeling of Novel Two-Phase Heat Transfer Device for Thermal Management of Light Emitting Diodes

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Karthik S. Remella ◽  
Frank M. Gerner ◽  
Ahmed Shuja
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Management ◽  
Light Emitting Diodes ◽  
Working Fluid ◽  
Two Phase ◽  
Light Emitting ◽  
Phase Mixture ◽  
Two Phase Heat Transfer ◽  
Transfer Device

The paper introduces a novel two-phase heat transfer device (TPHTD) which is employed in the thermal management of light emitting diodes (LEDs). The heat transfer device structurally resembles a conventional loop heat pipe (LHP) without a compensation chamber, but operates very differently from it. The device is comprised of a central evaporator package and a circular coil that acts as a heat exchanger loop. The working fluid leaving the evaporator has a two-phase mixture quality of approximately 0.2. Having introduced the device, the paper delineates a mathematical model for predicting its thermal performance. The primary objective of the model is to provide a fundamental understanding of the operation of the device. A one-dimensional thermal resistance model (TRM) is utilized in modeling the evaporator. The paper presents a detailed discussion on obtaining these resistances from experiments conducted on the device. A correlation for the external heat transfer coefficient of the heat exchanger loop is proposed based on experiments and is found to be in good agreement with literature. The model predicts performance parameters such as board temperature, two-phase mixture quality, and saturation and subcooled temperatures (Tsat and Tsc) of the working fluid for different input thermal powers (Qtot). Based on experimental evidence, it is concluded that the majority of Qtot (∼75%) is utilized in phase change of the working fluid, and the rest reheats the working fluid from a lower subcooled temperature (Tsc) to the saturation temperature (Tsat) of the evaporator.

Experimental Characterization of a Unique Carbon Fiber Brush Heat Sink in Two-Phase Heat Transfer

2005 ◽  
Author(s):  
Harish Chengalvala ◽  
Amy S. Fleischer ◽  
G. F. Jones
Keyword(s):  
Heat Transfer ◽  
Carbon Fiber ◽  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Management Strategies ◽  
Liquid Cooling ◽  
Two Phase ◽  
Two Phase Heat Transfer ◽  
Power Densities

The performance enhancements and footprint decreases of advanced electronic devices result in soaring power densities which may in turn lead to elevated operating temperatures. As elevated device temperatures lead to decreased device reliability and increased thermal stresses, it is necessary to employ aggressive thermal management techniques to maintain an acceptable junction temperature at high power densities. For this reason, interest is growing in a variety of liquid cooling techniques This study analyzes an advanced engineered-material heat sink which provides significant improvements in thermal management strategies for advanced electronics. The heat sink consists of a very large number of small cross-section fins fabricated from carbon pitch fibers. For these carbon pitch fibers, the high thermal conductivity reduces the temperature drop along the length of the fin creating a longer effective fin length than for copper fins. The longer length results in more heat transfer surface area and a more effective heat sink. In liquid cooling, the rough surface of the fin will provide multiple bubble nucleation sites, strongly promoting active two-phase heat transfer over the entire fin surface. This surface enhancement is expected to lead to significant increases in performance over conventional heat sinks. This experimental analysis characterizes the thermal performance of the carbon-fiber heat sink in two-phase closed loop thermosyphon operation using FC72 as the operating fluid. The influence of power load, thermosyphon fill volume and condenser operating temperature on the overall thermal performance is examined. The results of this experiment provide significant insight into the possible implementation and benefits of carbon fiber heat sink technology in two-phase flow leading to significant improvements in thermal management strategies for advanced electronics.

MICROSCALE TWO PHASE HEAT TRANSFER ENHANCEMENT IN POROUS STRUCTURES

Equipment ◽  
2006 ◽  
Author(s):  
Leonid L. Vasiliev ◽  
A. Zhuravlyov ◽  
A. Shapovalov ◽  
L. L. Vasiliev, Jr
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Porous Structures ◽  
Transfer Enhancement ◽  
Two Phase ◽  
Two Phase Heat Transfer

Reduced Pressure Boiling Heat Transfer in Rectangular Microchannels With Interconnected Reentrant Cavities

2005 ◽  
Vol 127 (10) ◽  
pp. 1106-1114 ◽  
Author(s):  
Ali Koşar ◽  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Transfer ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Convective Boiling ◽  
Reduced Pressure ◽  
Exit Pressure ◽  
Mass Fluxes ◽  
Mechanism Transition ◽  
Two Phase Heat Transfer

Boiling flow of deionized water through 227μm hydraulic diameter microchannels with 7.5μm wide interconnected reentrant cavities at 47 kPa exit pressure has been investigated. Average two-phase heat transfer coefficients have been obtained over effective heat fluxes ranging from 28 to 445W∕cm2 and mass fluxes from 41 to 302kg∕m2s. A map is developed that divides the data into two regions where the heat transfer mechanisms are nucleation or convective boiling dominant. The map is compared to similar atmospheric exit pressure data developed in a previous study. A boiling mechanism transition criterion based on the Reynolds number and the Kandlikar k1 number is proposed.

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