Comparison tests of loop heat pipes with flat evaporators of different types

Comparison tests have been conducted on a flat-oval evaporator with a longitudinal replenishment of the evaporation zone with a working fluid (ELR) measuring 110 x 50.5 x 10 mm(3) and a flat disk-shaped evaporator with opposite replenishment (EOR) 50 mm in diameter and 19 mm in thickness. The evaporators have been tested as parts of copper-water loop heat pipes (LHPs) with identical design parameters, with a heat source of 40 x 40 mm(2) at a heat sink temperature of 40 degrees C. It is shown that an LHP with an ELR has a significantly lower operating temperature in the whole range of heat loads. The maximum heat load of the device with an ELR was 800 W at an evaporator temperature of 109.5 degrees C and with an EOR it was 600 W at a temperature of 121.1 degrees C. The corresponding thermal resistances of the evaporators were 0.025 degrees C/W and 0.046 degrees C/W. At a nominal heat load of 300 W the ELR temperature was 70.2 degrees C and the EOR temperature 87.4 degrees C . The devices were designed for use in energy-efficient cooling systems for high-power electronics. A computer simulation of heat exchange processes in the evaporators was carried out taking into account parasitic heat flows into the compensation chamber. (c) 2021 Elsevier Ltd. All rights reserved.