Performance Improvement in Loop Heat Pipe Using Primary Wick with Circumferential Grooves

Abstract

This paper presents an investigation of 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, which resulted in better thermal performance. When the LHP operates at its maximum operational heat load, the heat source temperature for the evaporator with the primary wick with circumferential grooves is kept at levels 50% lower then when using the one with axial grooves. Besides the fact the 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. This represents a possibility of using the new designed LHPs operating at higher heat loads while keeping the source temperature at lower levels.