High performance copper-water heat pipes with nanoengineered evaporator sections

Abstract This experimental investigation aims to enhance the performance of heat pipes through nanoengineering the evaporator section, by integrating hydrophilic copper oxide (CuO) nanowires on the inner surface. Two types of CuO nanowires have been employed. Copper pipes measuring 440 mm in length with 12.7 mm O.D. and 0.8 mm wall thickness with inner grooves were used to manufacture heat pipes. All heat pipes were charged with ultra-filtered deionized (DI) water as a working fluid. By employing the hydrophilic CuO nanowires coating in the evaporator section of a heat pipe, its performance is substantially enhanced compared to a heat pipe with identical dimensions without the coating. Specifically, thermal resistance is reduced by 81.2% when using Type I CuO and 72% using Type II CuO nanowires compared to a heat pipe without coatings. The effects of the working load and orientation on the heat pipe thermal resistance have been systematically examined.