Three-Dimensional Numerical Analysis of Mini-Grooved Flat Heat Pipe Filled with Different Working Fluids with Experimental Validation

Abstract

Mini-grooved flat heat pipe (FHP) is an efficient approach to cool the electronics within small space. As it was hard to measure the flow and thermal characteristics inside the FHP, a novel three-dimensional model was set up to couple velocity, pressure, temperature, and mass transport inside the FHP, anticipating understanding the working mechanisms of FHP filled with different working fluids under transient and steady states. Temperature-dependent physical properties of working fluid and simulated thermal conductivity of wick were employed. The numerical results were validated by experiment with the maximum deviations in thermal resistance and maximum temperature of 17.9% and 5.0%, respectively. It was found that working fluid types, properties and input heat affected the FHP performance. The deionized water filled FHP shows more excellent thermal characteristics. Under input heat of 10 W, the thermal resistance, maximum temperature, and temperature nonuniformity of deionized water filled FHP were numerically lower than those of anhydrous ethanol filled FHP by 48.1%, 11.5% and 56.4%, and lower than those of hexane filled FHP by 54.4%, 14.3% and 62.6%, respectively. However, the starting performance of deionized water filled FHP is comparatively poorer. FHP filled with anhydrous ethanol or hexane is more appealing for electronics cooling.