Experimental investigation on the thermal performance of a novel loop heat pipe (LHP) with micro-channel structure

Abstract

Loop heat pipe (LHP) is widely used to solve the problem of high heat flux in electronic chips due to its excellent heat transfer efficiency, good thermal equilibrium, and large heat transfer limit. To further improve the heat transfer efficiency of the LHP, a novel LHP was designed with a parallel arrangement of 13 vapor channels (2 mm × 2 mm) capillary wick structure. Experimental investigations were conducted to evaluate the start-up and steady-state performance of the LHP under both regular and random variable loads ranging from 30 W to 180 W. The findings indicate that the LHP exhibits rapid start-up and operates smoothly within the heat load range of 30 W–180 W, maintaining the heat source temperature below 75 °C, thereby meeting the temperature requirements for chip operation.Under a regular variable heat load, the LHP experiences minimal temperature fluctuations, but the system operated with good stability. Meanwhile, under random variable heat loads, the LHP demonstrates quick responsiveness within 5 s and reaches a stable state within 8 min. The temperature fluctuations remain within 2 °C, effectively fulfilling the temperature control demands of electronic devices. Furthermore, the evaporator thermal resistance, condenser thermal resistance, loop thermal resistance and system thermal resistance of the LHP gradually decrease with increasing of heat load. When reaching a heat load of 180 W, the evaporator thermal resistance (Re), condenser thermal resistance (Rc), loop thermal resistance (RLHP), and system thermal resistance (Rsys) reach their minimum, with values of 0.0168 °C/W, 0.121 °C/W,0.137 °C/W and 0.229 °C/W, respectively. In comparison with other LHPs, the evaporator temperature was only 59.56 °C with the highest heat load of 210 W (52.5 W/cm2), which expanded the application range of the LHP for electronic devices cooling.