Experimental study on thermal performance of loop heat pipe with a composite-material evaporator for cooling of electronics

A loop heat pipe (LHP) is one of the most efficient two-phase heat transfer devices. During its operation, a portion of the heat load applied to the evaporator is transferred to its compensation chamber (CC) through the evaporator sidewall, which is known as a heat leak, decreasing the performance of the LHP startup to a certain degree. To reduce a heat leak through the evaporator sidewall, an LHP with a composite-material evaporator was proposed. The evaporator is composed of two types of material, namely, red copper (heating surface) and 316L stainless steel (upper part), and has a reinforced rib structure on the heating surface to improve the evaporator strength. Two sintered nickel wicks are incorporated inside the evaporator. The experimental results demonstrate that the LHP with a composite-material evaporator can operate successfully within a heat load range of 10–140 W while heating the surface to below 80 °C at a heat sink temperature of 25 °C and 35 °C. Compared with an LHP with the same evaporator structure (but with a different in material) [17], the temperature difference between the evaporator outlet and the CC left (right) is smaller under the same heat load, indicating that the heat leak through the evaporator sidewall is reduced.