Heat Transfer and Pressure Loss Characteristics of a Channel Flow with Fibrous Aluminum Layer

Abstract

Heat transfer experiment and pressure loss measurement have been done for the channel flow with aluminum fiber layers in order to investigate their effectiveness as an insertion device to improve the heat exchanger's performance. Aluminum fiber layers focused in this paper are composed of aluminum fibers of 100 μm in diameter, once laminated as a non-woven fabric and then hardened by diffusion bonding as a bulk insertion body, and are expected to attain large heat transfer enhancement due to their high thermal conductivity and fine heat spread structures. Since heat conduction anisotropy exists in such fibrous layers, mainly two orientations, that is, fibers axes parallel and perpendicular to the heat transfer wall, were tested as parameter in addition to the other parameters, such as the porosity and the bonding method to the wall. It was found that the aluminum fiber layers with their axes mainly perpendicular to the wall showed quite high heat transfer performance, that is, heat transfer of twenty times as large as that of the non insertion case was obtained, although quite large pressure loss was required.