LAUSR

In this paper, the visualization of the thermo-hydrodynamic behavior in flat-plate pulsating heat pipe (FP-PHP) with HFE-347 is experimentally investigated. The FP-PHP is vertically placed with filling rate of 20% to 70% and heating power of 20 W to 140 W. A high-speed camera is used to record the two-phase flow in the FP-PHP. Four flow pattern types and four flow directions are observed. The flow directions of the two-phase flow inside the FP-PHP with medium filling rate (40%–60%) are the most complex, and the FP-PHP with high filling rate (70%) is most likely to form a directional circulating flow. At high heating power (100 W to 140 W), the flow patterns in FP-PHP with medium (40%–60%) and high filling rate (70%) are dominated by mixed flow. The wall temperature fluctuates greatly at moderate heating power (60 W to 80 W) owing to the uncertainty of the flow direction. The temperature distribution of the FP-PHP is highly affected by the heat transfer intensity of the working fluid under different flow states, so that the state of fluid flow and the thermal performance of FP-PHP can be evaluated through the infrared thermal image of the FP-PHP.