Measurement and numerical simulation on the heat transfer characteristics of reciprocating flow in microchannels for the application in magnetic refrigeration

Experimental and numerical studies were conducted on the heat transfer characteristics of reciprocating flow in different types of microchannels for the application in the active magnetic regenerator (AMR) of magnetic refrigeration systems. Experimental measurements were performed for a flat plate type microchannel fabricated using MEMS technique, and with intermittent heating as the boundary condition. The results of the experiments are in good accordance with those of 2-D numerical simulations conducted using the same conditions as the experiments. Therefore, it is considered that the numerical mode is effective for evaluation of the heat transfer for reciprocating flow. Furthermore, numerical simulations on two types of microchannel (flat plate type and staggered mini-plates type) were conducted with alternative heating and cooling conditions which corresponding to the volumetric temperature rise/drop of solid material as a result of magnetocaloric effect. The influence of various factors on the heat transport of reciprocating flow was analyzed. It was found that enhancement of the heat transport could be realized by utilizing the microchannel of staggered mini-plates type, and there is an optimum ratio of amplitude to flow channel length (ΔL/L) to achieve high efficiency heat transport.