Heat transfer investigation of a flat-plate oscillating heat pipe with tandem dual channels under nonuniform heating

Abstract To provide cooling of electronics under nonuniform heating from multiple heat sources, a novel tandem dual-channel flat-plate oscillating heat pipe (OHP) is tailored and experimentally studied with a “center-multiple-heat-source nonuniform heating and two-end air cooling” layout under different inclination angles, heat loads and nonuniform heating levels. Flow pattern diagrams together with thermal resistance contour maps are organized for two tandem mirror-symmetric halves of the flat-plate OHP, and the thermal performance differences under nonuniform and uniform heating are compared. It is indicated that, compared with uniform heating, nonuniform heating produces better thermohydrodynamic performance at a low heat load with quasi-steady “stop-oscillation” fluid motion in the flat-plate OHP, while it results in poorer thermohydrodynamic performance when the heat load is large enough to maintain sustainable fluid flow in the flat-plate OHP. Under nonuniform heating conditions, concentrating more heat to overcome the negative effects rather than to amplify the positive effects on the fluid flow and heat transfer in OHPs is more beneficial to the overall thermal performance. For the 540 tested conditions, the flat-plate OHP has a much smaller overall thermal resistance than a pure 6063 aluminum alloy plate with the same configuration (approximately 15.3% on average) along a heat transfer distance of 101.8 mm. In addition, it possesses good adaptability to gravity, with coefficients of variation of 27.6% in the overall thermal resistance for inclination angles from 0° to 90°. Accordingly, this flat-plate OHP has good potential for high-efficiency and good-adaptability cooling of electronics under nonuniform heating by multiple heat sources.