STUDY ON TWO-PHASE FLOW AND TEMPERATURE UNIFORMITY CHARACTERISTICS OF MICROCHANNEL HEAT PIPE

In order to offset the local heat flux concentration phenomenon and ensure the steady performance of electronics, a test apparatus for evaluating the thermal performance of a microchannel heat pipe was constructed to investigate the thermal uniformity of the microchannel heat pipe under varying heat source placements. The experimental findings indicate that at a power of 25 W with the heat source positioned on plane C, the overall thermal resistance of the heat pipe differs by 60.1% compared to the local thermal resistance. Furthermore, the heat pipe exhibits a minimum overall thermal resistance of 0.3 K/W, highlighting improved temperature uniformity and quicker start-up performance. The mathematical model based on the lattice Boltzmann method is established and the dynamic operation mechanism of boiling and condensation under the action of local heat source in closed space is discussed. The simulation results suggested that when the heat source is positioned centrally on the underside, the diffusion of the working fluid vapor becomes more uniform and the most intense boiling occurs. The boiling of the working fluid in this area results in the most frequent and intense periodic improvement in heat transfer, thus achieving optimal thermal performance in terms of temperature distribution for the heat pipe.