Thermal performance of modified polymeric heatsinks as an alternative for aluminum in heat rejection systems

Abstract

Many studies have been conducted to obtain a viable alternative for metallic compartments in heat exchangers. The present research has been conducted to distinctly reveal the performance characteristics of polymer based composite materials as heat transfer medium. Various prototypes of polymeric fins with different volume fractions for multiwalled-carbon nanotubes, copper as components, and high density polyethylene (HDPE) as a matrix, were fabricated and stacked around copper pipes as an air/water finned-pipe heat exchanger. The thermal performance of each case was tested and compared with those of aluminum fins under the same conditions in a miniature mechanically pumped cooling loop (MPCL). Results indicate that for the airside, the difference between total heat transfer rates of the aluminum heat sink increased more rapidly than that of polymeric cases at the beginning, and became constant when a certain Reynolds number is reached. Further, for the best case of new composite heat sinks, a 451% and 52% enhancement in thermal conductivity and heat rejection were achieved, respectively, compared with the pure HDPE. The thermographic method also was used for better visual comparison among the materials. Finally, numerical simulations using ANSYS Fluent, indicated consistency with the experimental results of heat distribution for each case.