Methods of Controlling the Loop Heat Pipe Operating Temperature

2008 ◽  
Author(s):  
Jentung Ku
Keyword(s):  
Heat Pipe ◽  
Operating Temperature ◽  
Loop Heat Pipe

Hydraulic operating temperature control of a loop heat pipe

2015 ◽  
Vol 86 ◽  
pp. 796-808 ◽  
Author(s):  
Wukchul Joung ◽  
Kee Sool Gam ◽  
Yong-Gyoo Kim ◽  
Inseok Yang
Keyword(s):  
Heat Pipe ◽  
Temperature Control ◽  
Operating Temperature ◽  
Loop Heat Pipe

Loop Heat Pipe Operating Temperature Dependence on Liquid Line Return Temperature

2004 ◽  
Author(s):  
Paul Rogers ◽  
Jeffrey Perez ◽  
Jentung Ku ◽  
Mark Kobel ◽  
Jay Ochterbeck ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Heat Pipe ◽  
Operating Temperature ◽  
Loop Heat Pipe ◽  
Liquid Line

Steady State Modeling of LHP and Analysis

2010 ◽  
Author(s):  
Yan Chen ◽  
Lin Cheng ◽  
Gongming Xin ◽  
Tao Luan
Keyword(s):  
Steady State ◽  
Ambient Temperature ◽  
Heat Pipe ◽  
Heat Sink ◽  
Heat Load ◽  
Operating Temperature ◽  
Working Fluid ◽  
Loop Heat Pipe ◽  
Heat Sink Temperature ◽  
Transition Heat

The loop heat pipe (LHP) was invented in Russia in the early 1980’s. It is a two-phase heat transfer device that utilizes the evaporation and condensation of a working fluid to transfer heat, and the capillary force developed in fine porous wicks to circulate the fluid. The temperature of LHP evaporator as functions of the heat load, sink temperature, ambient temperature is an important parameter which can reflect the performance of an LHP. Many factors can affect the LHP operating temperature and which can be divided into two parts: external and internal. The external factors including heat sink temperature, ambient temperature, fluid forces, the position between heat source and heat sink and the heat exchange between LHP and ambient. The internal factors related to the design and structure of the LHP, for example, the charging amount of the working fluid and the distribution status of the liquid phase during the LHP operating. Based on Sinda/Fluint software an ammonia-stainless steel steady state model of loop heat pipe was established, the impacts on the LHP operating temperature induced by alterable heat loads under 3 operating cases (the different position between evaporator and condenser, the changing of ambient temperature and the changing of heat sink temperature) were analyzed and conclusions were made. Changing the position between evaporator and condenser has a significant influence on the LHP operating temperature. Anti-gravity operation will reduce the performance of the LHP, this phenomenon is obviously in low heat load range. Further more, increasing of fluid pressure drop in the loop will induce decreasing of the LHP performance. The temperature difference between ambient and heat sink will influence the transition heat load (from variable conductance mode to fixed conductance mode), the bigger the temperature difference the higher the transition heat load.

Thermal Vacuum Testing of a Miniature Loop Heat Pipe With Multiple Evaporators and Multiple Condensers

2007 ◽  
Author(s):  
Jentung Ku ◽  
Laura Ottenstein ◽  
Hosei Nagano
Keyword(s):  
Low Power ◽  
Heat Pipe ◽  
Temperature Control ◽  
Heat Load ◽  
Operating Temperature ◽  
Loop Heat Pipe ◽  
Thermal Vacuum ◽  
Heater Power ◽  
Start Up ◽  
Vacuum Testing

This paper describes thermal vacuum testing of a miniature loop heat pipe (MLHP) with two evaporators and two condensers designed for future small systems applications requiring low mass, low power and compactness. Each evaporator contains a wick with an outer diameter of 6.4 mm, and each has its own integral compensation chamber (CC). Multiple evaporators provide flexibility for placement of instruments that need to be maintained at the same temperature, and facilitate heat load sharing among instruments, resulting in a reduced auxiliary heater power requirement. A flow regulator is used to regulate heat dissipations among all condensers, thus providing flexibility for placement of radiators on the spacecraft. A thermoelectric converter (TEC) is attached to each CC for operating temperature control and enhancement of start-up success. Tests performed include start-up, power cycle, sink temperature cycle, high power and low power operation, heat load sharing, and operating temperature control. The MLHP demonstrated excellent performance in the thermal vacuum environment. The loop started successfully and operated stably under various evaporator heat loads and condenser sink temperatures. The TECs were able to maintain the loop operating temperature within ±0.5K of the desired set point temperature at all power levels and all sink temperatures. The un-powered evaporator would automatically share heat from the other powered evaporator. The CC control heater power was reduced by more than 50 percent when a TEC was used instead of conventional electrical heaters. The flow regulator was able to regulate the heat dissipation among the radiators and prevent vapor from flowing into the liquid line.

scholarly journals Effect of evaporator tilt on the operating temperature of a loop heat pipe without a secondary wick

2014 ◽  
Vol 77 ◽  
pp. 600-603 ◽  
Author(s):  
Lizhan Bai ◽  
Guiping Lin ◽  
Hongxing Zhang ◽  
Dongsheng Wen
Keyword(s):  
Heat Pipe ◽  
Operating Temperature ◽  
Loop Heat Pipe
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