Visual Observation and Analytical Study of the Heat Load Sharing Mode in Multi-Evaporator Loop Heat Pipe

Abstract

Abstract In this paper, the operating characteristics of the heat load sharing mode of multiple-evaporator loop heat pipe (MLHP) were elucidated based on a visual observation test. The heat load sharing mode is a function of MLHPs that can share the heat between the evaporators through the vapor without electronic power for the heat storage utilization. A visualized MLHP with two evaporators and one condenser was designed and fabricated. To simulate the heat load sharing mode in the MLHP, one evaporator was heated in the range of 40–280 W and the other evaporator was cooled using a water jacket in the range of 10–80 °C. Under the heat load sharing mode, the flow behaviors in the evaporator cores and the compensation chambers were visually observed using borescope cameras, respectively. Moreover, two operating modes (defined as Mode A and Mode B) that affect the maximum heat sharing capability were identified. In Mode A, the heat sharing rate was proportional to the heat dissipation at the cooled side of evaporator, where the capillary force at the wick significantly affected the operation mode. By contrast, in Mode B, the heat sharing rate reached the upper limit and then was constant regardless of the heat dissipation. Furthermore, the proposed concept model can predict the transition of the operation mode from Mode A to Mode B.