Thermal performance of loop heat pipe with porous copper fiber sintered sheet as wick structure

Novel porous copper fiber sintered sheets (PCFSSs), with both single and composite porosities, were fabricated by the low-temperature solid-phase sintering technology. Subsequently, a new type of loop heat pipe (LHP) was constructed with the PCFSS as its wick structure. Results show that the capillary suction height is increased with porosity decreasing from 90% to 60%. With the single-porosity PCFSS, the evaporator wall temperature and the thermal resistance gradually decrease with the decreasing porosity. Compared to a single-porosity PCFSS, the LHP with a composite-porosity PCFSS as its wick structure shows a lower evaporator wall temperature and thermal resistance, and its start-up time reduces slightly because of the enhanced heat transfer and reduced back heat leak. The lowest evaporator wall temperature and minimum thermal resistance are obtained with the 70% + 60% composite-porosity PCFSS, while the larger porosity is closer to the heat source. When the evaporator temperature is controlled to remain less than 100 °C, the proposed LHPs tolerate a maximum heat load of 200 W, with thermal resistance of 0.047 °C/W.