Numerical and experimental investigations of the heat transfer and fatigue life of a new W-type mini microchannel heat exchanger

Abstract

To solve the problems of heat dissipation and improve the reliability of high heat flux electronic devices, a new W-type mini microchannel heat exchanger is proposed. Firstly, the effect of the inlet and outlet positions on the flow and thermal behaviors are discussed. Secondly, two traditional heat sinks are introduced to compare the cooling ability with the new exchanger. The results shows that the temperature difference of W-type heat exchanger is 10.4 K, which is lower than that of the two traditional channels. Thirdly, the effect of width for the intermediate channel and inlet annular channel length on heat transfer characteristics are analyzed. The results indicate that when the width of the intermediate channel is 4 mm and the channel length is 15.5 mm, the temperature uniformity of the heat exchanger is the best with appropriate pressure drop. On this basis, the experimental test is carried out to verify the numerical results. It is found that the maximum Nusselt number and pressure drop errors between numerical and experimental tests are 8.01% and 5.06%, respectively, which verifies the correctness of the numerical results. In addition, the strength of the heat exchanger is checked, and the maximum working stress is 249.76 MPa indicating that the strength of the heat exchanger meets the using requirements. Finally, the influence of ambient temperature on the fatigue life of heat exchanger is analyzed. The results show that the fatigue life presents a trapezoidal trend with the change of ambient temperature. Moreover, the numerical correlation of fatigue life is achieved.