Cross flow heat exchange of textile cellular metal core sandwich panels

This paper presents a combined experimental and theoretical study on the thermal-hydraulic performance of a novel type of periodic textile cellular structure, subjected to forced convection using both air and water as a coolant. The samples were fabricated as sandwich panels, with the textile cores bonded to two solid face-sheets using a brazing alloy. These efficient load supporting sandwich structures can also be used for active cooling. The effects of cell topology, pore fraction and material properties (high thermal conductivity copper or low thermal conductivity stainless steel) on both coolants flow resistance and heat transfer rate were measured. The flow friction factor is found to depend mainly on the open area ratio in the flow direction (which is dependent upon cell topology and pore fraction), whilst the amount of heat transferred is dependent upon solid conductivity, pore fraction and surface area density. Analytical models were used to develop predictive relations between both the pressure loss and heat transfer performance for different textile geometries. Good agreement between the predictions and measurements were obtained. Due to high thermal capacity of water, it was found that the model for water cooling must account for the additional contribution due to thermal dispersion. The dispersion conductivity was found to be related to coolant property, local How velocity, wire diameter and pore fraction. Finally, the thermal performance of brazed woven textiles is compared with other heat exchanger media, such as open-celled metallic foams and louvered fins. (C) 2007 Elsevier Ltd. All rights reserved.