Visualization study on boiling heat transfer of ultra-thin flat heat pipe with single layer wire mesh wick

In this paper, an experimental study on the ultra-thin flat heat pipe with a single-layer wire mesh core is carried out through a visual experimental platform. Combined with the analysis of temperature and phenomena, it is found that the peak value of temperature fluctuation of ultra-thin flat heat pipe is affected by thermal load, and the period of temperature fluctuation is an integral multiple of the working fluid flow. The working modes of the ultra-thin flat-plate heat pipe under different heat loads include evaporation heat transfer, subcooled boiling heat transfer, nucleated boiling heat transfer and the drying zone beyond the heat transfer limit. When the boiling working medium in the ultra-thin finite cavity enters the nucleate boiling zone, the thermal resistance in the evaporation section will decrease and the thermal resistance in the condensation section will increase slightly. The overall thermal resistance shows certain regularity, with the minimum value about 21.7% lower than the maximum value. Under the condition of sufficient condensation reflux, the heat resistance of the ultra-thin flat heat pipe reaches the minimum when the oscillation intensity of the vapor-liquid two-phase working medium reaches the maximum. (C) 2021 Elsevier Ltd. All rights reserved.