Experimental investigation of loop heat pipe with a large squared evaporator for multi-heat sources cooling

Abstract

A heating area of 190 mm × 90 mm large flat-plate loop heat pipe was designed for the heat dissipation problem of multi-heat sources. The design process was also briefly introduced. The evaporator was made of aluminum alloy, and heat dissipation fins were arranged on the back side of the compensation chamber to enhance the heat transfer between the compensation and the ambient. The stainless steel wire mesh worked as the porous wick, and the acetone was chosen as the working fluid. Six ceramics heating blocks were used as the heat sources. The results showed that the system could start up and work normally between 20 W–140 W, and maintained the heating surface temperature below 90 °C. The system behaved as a zigzag start below 20 W, and the condenser inlet temperature oscillated periodically, and the system could start up stably between 25 W and 140 W. When the heat load was increased, there occurred periodic temperature fluctuation in condenser outlet. The system could establish a new balance quickly during variable heat loads operation, which reflected the good reliability of the LHP. The experiment of changing the heat dissipation condition on the condenser side and the evaporator side was carried out. When the heat load was 120 W and the ambient temperature was constant, the system equilibrium temperature difference caused by the air ventilation of the condenser was changed, which was less than the heat dissipation of the evaporator under the same conditions. The evaporator thermal resistance decreased with the increase in heat load, and the minimum thermal resistance of 0.032 °C/W was achieved at the heat load of 120 W. The total thermal resistance of the LHP was distributed between 0.312 °C/W and 0.212 °C/W. It was also pointed out that it was very important to improve the thermal uniformity of the heated surface of a large-plane loop heat pipe system with multiple heat sources.