Analysis of thermal and hydraulic performance of V-shape corrugated carbon foam

摘要

A study of the hydraulic and thermal characteristics of V-shape corrugated carbon foams in air flow is presented. The hydraulic performance is assessed by the pressure drop across the foam while thermal performance is evaluated by the overall heat transfer coefficient. Numerical solution, using Finite Element Method (FEM), is established and validated with experimental data. Foam geometries under study are further analyzed to better understand the transport process within the porous matrix. Four different V-shape corrugated carbon foam geometries are selected based on design considerations and availability. Foam geometries under study have varying lengths and heights. The foam length is chosen to be 25.4, 38.1 or 52.1 mm while the height is 6.8 or 11.7 mm. The wall thickness for all geometries is 2.5 mm. The effects of the foam length and height on thermal and hydraulic performance are presented and discussed. For laminar flow of air with an average inlet velocity of 0.71-4 m/s, the pressure drop ranges from 53 to 531 Pa and the heat transfer coefficient ranges from 186 to 1602 W/m~2 K. A key finding from the present analysis is that the heat transfer efficiency of the foam approaches unity within a distance of 1.2 mm (or about 3 pore size) upon air penetrating into the foam, which means there is no significant heat transfer occurring after this distance. This establishes the foundation for the design of corrugated foam to maximize the thermal performance while minimizing the pressure drop.