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Capillary Limit in a Loop Heat Pipe with Dual Evaporators
Technical Paper
2002-01-2503
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
This paper describes a study on the capillary limit of a loop heat pipe (LHP) with two evaporators and two condensers. Both theoretical analysis and experimental investigation are performed. Experimental tests conducted include heat load to one evaporator only, even heat loads to both evaporators, and uneven heat loads to both evaporators. Test results show that after the capillary limit is exceeded, vapor will penetrate through the wick of the weaker evaporator, and the compensation chamber (CC) of that evaporator will control the loop operating temperature regardless of which CC has been in control prior to the event. Because the evaporator can tolerate vapor bubbles, the loop can continue to work after vapor penetration. As the loop operating temperature increases, the system pressure drop actually decreases due to a decrease in liquid and vapor viscosities. Thus, the loop may reach a new steady state at a higher operating temperature after vapor penetration. Furthermore, this process can be repeated with a modest increase in the heat load each time the capillary limit is exceeded until the evaporator temperature exceeds the maximum allowable value. When the heat load is applied to only one of the evaporators, the capillary limit can be identified by a rapid increase in the operating temperature and in the temperature difference between the evaporator and the CC. However, it is more difficult to identify when the capillary limit is exceeded if the heat load is applied to both evaporators. In all cases, the loop can recover by reducing the heat load to the loop.
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Citation
Ku, J. and Birur, G., "Capillary Limit in a Loop Heat Pipe with Dual Evaporators," SAE Technical Paper 2002-01-2503, 2002, https://doi.org/10.4271/2002-01-2503.Also In
References
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- Bienert, W. B. et al. The Proof-of-Feasibility of Multiple Evaporator Loop Heat Pipes, 10th International Heat Pipe Conference, Stuggart, Germany September 1997
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- Goncharov, K. A. Golovin, O. A. Kolesnikov, V. A. Loop Heat Pipe with Several Evaporators, SAE Paper No. 2000-01-2407 2000
- Ku, J. Birur, G. An Experimental Study of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers, SAE Paper No. 2001-01-2189 2001
- Ku, J. Birur, G. Testing of a Loop Heat Pipe with Two Evaporators and Two Condensers, SAE Paper No. 2001-01-2190 2001
- Ku, J. Birur, G. Active Control of the Operating Temperature in a Loop Heat Pipe with Two Evaporators and Two Condensers, SAE Paper No. 2001-01-2188 2001
- Ku, J. Ottenstein, L Rogers, P. Cheung, K. Capillary Limit in a Loop Heat Pipe with a Single Evaporator,” SAE paper No. 2002-01-2502 2002