Performance investigation of a compact loop heat pipe with parallel condensers

• Comparisons of LHPs with different condenser configurations were conducted.
• Operation characteristics for the LHP with parallel condensers were identified.
• High heat flux of 120 W/cm2 was achieved for the LHP with forced air cooling.
• The compact LHP can manage a wide range of heat loads.

Two compact copper–water loop heat pipes (LHP) with flat plate evaporators were fabricated and tested in this study: one with a single condenser and the other with dual parallel condensers. A series of experiments were carried out to compare their heat transfer performance and operating behavior in stepwise heat loads with the assistance of an infrared thermographic technique. A maximum heating power of 1500 W (∼100 W/cm2) for the LHP with individual condenser and 1700 W (∼120 W/cm2) for the LHP with dual parallel condensers were obtained under forced air cooling condition when the vapor temperature in the evaporator was below 100 °C, and the corresponding total thermal resistance from the heating source to the ambient were 0.072 °C/W for the LHP with individual condenser and 0.067 °C/W for the LHP with dual parallel condensers, respectively. In addition, the uneven-distribution of working fluid into different condensers existed at comparatively low heat loads for the loop heat pipe with dual parallel condensers, which could bring forth deleterious consequences. Further visual investigations are needed to help better understanding the operation mechanism of the LHP with dual parallel condensers.