Experimental study on multi-layered type of gas-to-gas heat exchanger using porous media

Based on an effective energy conversion method between flowing gas enthalpy and thermal radiation, a multi-layered type of gas-to-gas heat exchanger using porous media has been proposed. A series of experiments have been conducted for the inlet temperature of high temperature gas 300–700 °C, the optical thickness of porous media 0–15.4, the number of layers 2–5 and two types of walls (bare or finned) placed in the system. As a result, a heat recovery section is shown to play an important role in lowering an outer wall temperature of the system and at the same time in increasing the total heat recovery rate Htot,N. In addition, it is clarified that the optical thickness of about 8 is enough to obtain sufficient Htot,N, and the finned walls are quite effective to promote Htot,N under the present experimental conditions.