Loop heat pipe performance enhancement using primary wick with circumferential grooves

This paper presents an investigation of loop heat pipes (LHPs) that operate with acetone as working fluid, for maximum operational heat loads of 80 W, where the results of tests performed in laboratory conditions are presented. Two identical LHPs were tested, where one presents the capillary evaporator primary wick with axial grooves, while the other presents the design of circumferential grooves and both evaporators present microgrooves in their internal diameter. For the same active length, there has been a gain of 20% on the contact area when using circumferential grooves on the primary wick. When the LHP operates at its maximum operational heat load, the heat source temperatures for the evaporator with the primary wick with circumferential grooves are kept at levels 50% lower then when using the one with axial grooves. Besides the fact that an increase on the contact area has been achieved, other factors related to the design of the capillary evaporator have also resulted in the overall improvement, which were also verified with the results obtained from a mathematical model. This represents a possibility of using the new designed LHPs operating at higher heat loads while keeping the source temperatures at lower levels.