Testing of A Loop Heat Pipe Subjected to Variable Accelerating Forces, Part 1: Start-up

2000 ◽  
Author(s):  
Jentung Ku ◽  
Laura Ottenstein ◽  
Tarik Kaya ◽  
Paul Rogers ◽  
Craig Hoff
Keyword(s):  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Start Up

Experimental study of heat transfer and start-up of loop heat pipe with multiscale porous wicks

2017 ◽  
Vol 117 ◽  
pp. 782-798 ◽  
Author(s):  
Xianbing Ji ◽  
Ye Wang ◽  
Jinliang Xu ◽  
Yanping Huang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Start Up

Effect of Sink Temperature on the Stability of the Pressure-Controlled Loop Heat Pipe

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Wukchul Joung ◽  
Joohyun Lee
Keyword(s):  
Heat Pipe ◽  
Temperature Control ◽  
Control Technique ◽  
Loop Heat Pipe ◽  
Heat Leak ◽  
Start Up ◽  
Recent Emergence ◽  
Compensation Chamber ◽  
The Stability ◽  
Pressure Controlled

Recently, a novel temperature control technique utilizing the unique thermohydraulic operating principles of the pressure-controlled loop heat pipes (PCLHPs) was proposed and proved its effectiveness, by which a faster and more stable temperature control was possible by means of the pressure control. However, due to its recent emergence, the proposed hydraulic temperature control technique has not been fully characterized in terms of the various operating parameters including the sink temperature. In this work, the effect of the sink temperature on the loop heat pipe (LHP)-based hydraulic temperature control was investigated to improve the stability of the proposed technique. Start-up characteristics and transient responses of the operating temperatures to different pressure steps and sink temperatures were examined. From the test results, it was found that there was a minimum sink temperature, which ensured a steady-state operation after the start-up and a stable hydraulic temperature control with the increasing pressure steps, due to the unstable balance between the heat leak and the liquid subcooling in the compensation chamber at low sink temperatures. In addition, the range of the stable hydraulic temperature control was extended with the increasing coolant temperature due to the decreased heat leak, which resulted in the increased pressure difference between the evaporator and the compensation chamber. Therefore, it was found and suggested that for a stable hydraulic temperature control in an extended range, it was necessary to operate the PCLHP at higher sink temperatures than the low limit.

scholarly journals Heat-Transfer Characteristics of a Cryogenic Loop Heat Pipe for Space Applications

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1616
Author(s):  
Jaehwan Lee ◽  
Dongmin Kim ◽  
Jeongmin Mun ◽  
Seokho Kim
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Infrared Detectors ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Zero Gravity ◽  
Heat Transfer Characteristics ◽  
Space Applications ◽  
Transfer Characteristics ◽  
Start Up

Infrared detectors on satellites and spacecraft require cooling to increase their measurement sensitivity. To efficiently cool infrared detectors in a zero gravity environment and in limited spaces, a cryogenic loop heat pipe (CLHP) can be used to transfer heat over a certain distance by the capillary forces generated from porous wicks without a mechanical power source. The CLHP presented in this study transfers the heat load to a condenser 0.5 m away from an evaporator at temperatures below −150 °C. The CLHP with two evaporators includes a subloop for initial start-up, and uses a pressure reduction reservoir (PRR) for the supercritical start-up from room to cryogenic temperature. Nitrogen is used as the working fluid to verify the thermal behavior of the CLHP, and the heat-transfer capacity according to the nitrogen charging pressure of the PRR is investigated. To simulate a cryogenic environment, the CLHP is installed inside a space environment simulator, including a single-stage GM (Gifford McMahon) cryocooler to cool the condenser. The CLHP is horizontally installed to simulate zero gravity. The heat-transfer characteristics are experimentally evaluated through the loop circulation of the CLHP.

Start-Up Behavior of Double-Condenser Loop Heat Pipe

2005 ◽  
Author(s):  
Hiroki Nagai ◽  
M Muto ◽  
M Murakami ◽  
S Ueno
Keyword(s):  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Start Up

EXPERIMENTAL STUDY ON START-UP BEHAVIOR OF MINIATURE LOOP HEAT PIPE CONSIDERING EFFECT OF GRAVITY

2014 ◽  
Vol 5 (1-4) ◽  
pp. 483-490
Author(s):  
Hiroki Nagai ◽  
Hiromichi Tamamura ◽  
Hosei Nagano ◽  
Hiroyuki Ogawa
Keyword(s):  
Experimental Study ◽  
Heat Pipe ◽  
Loop Heat Pipe ◽  
Start Up

Mathematical Modeling of a Miniature Loop Heat Pipe With Two Evaporators and Two Condensers

2009 ◽  
Author(s):  
Jentung Ku ◽  
Triem Hoang ◽  
Tamara O’Connell
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Analytical Model ◽  
Computer Code ◽  
Loop Heat Pipe ◽  
Performance Tests ◽  
Thermal Vacuum ◽  
Start Up ◽  
Gravity Effects ◽  
Transient Thermal

A loop heat pipe (LHP) analytical model that simulates the steady state and transient thermal behaviors of LHPs with multiple evaporators and multiple condensers has recently been developed. It can be used as a stand-alone computer code or as a subroutine to general spacecraft thermal analyzers. Multi-evaporator and multi-condenser LHPs are more complex in their operation when compared to single-evaporator LHPs because of the thermal and fluid interactions among the evaporators, compensation chambers, and condensers. This analytical model has been used to simulate the thermal performance of a miniature loop heat pipe (MLHP) with two evaporators and two condensers in laboratory and thermal vacuum tests. In addition, the MLHP was tested in the laboratory under five different configurations where the relative elevations and tilts among loop components were varied so as to investigate the gravity effects on the loop performance and to verify the analytical model’s capability to predict such effects. The MLHP performance tests that were simulated included start-up, high power, heat transport limit, and heat load sharing between the two evaporators. In all tests that were modeled, the LHP analytical model accurately predicted the steady state and transient behaviors of the LHP. Furthermore, the model was run-time efficient and yielded stable solutions in all cases.

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