INFLUENCE OF PREPARATION METHOD AND THICKNESS ON HEAT TRANSFER PERFORMANCE OF POROUS COPPER FOAM WICK IN HEAT PIPES WITH Al2O3 NANOFLUID AS WORKING MEDIUM

摘要

The heat transfer performance of heat pipes with porous copper foam wick prepared by powder composite method and electrochemical deposition was investigated. Al2O3 nanofluids were used as working medium. The effects of different wick preparation methods and thickness on the heat transfer performance of the heat pipes were discussed. Results show that the thickness of the porous copper foam wick prepared by powder composite method remarkably influenced the heat transfer performance. In this paper, four different thicknesses (0.25, 0.5, 0.75, and 1.0 mm) were tested, of which 0.75 mm was found to be the optimum thickness that resulted in minimum thermal resistance and maximum heat transfer limit as well as enhanced isothermal characteristic. Under similar conditions, the porous copper foam wick prepared by powder composite method performed worse than the electrochemically deposited wick, although, theoretically, the former should have better wick material. The difference in the microstructure, surface features, and pore density caused by the different preparation methods may also significantly affect the heat transfer of the heat pipe as inferred from the heat transfer enhancement mechanism of the interaction of Al2O3 nanofluids in the heat pipes with porous copper wick.