梯度润湿表面脉动热管传热性能的研究

为提高脉动热管水平方向的运行性能，本文通过控制化学刻蚀时间，制备出冷凝段到蒸发段接触角由83.8°至0°均匀变化的纳米草结构梯度润湿表面。并将此结构引入至6弯管板式脉动热管中，在不同充液率、加热功率以及运行方向下开展可视化和传热性能试验。试验结果表明，在竖直运行时，梯度润湿表面脉动热管相比于纯铜脉动热管展现出较好的传热性能。水平方向上，相较于纯铜脉动热管几乎完全烧干、无法启动的情况，梯度润湿表面由于附加的梯度润湿驱动力，促进了液体工质的回流，脉动热管成功启动。且汽液界面脉动振幅、脉动速度以及脉动热管的传热性能显著提高，充液率50%时热阻最多降低45%。

Heat transfer performance of wettability gradient surface oscillating heat pipe

With the aim of enhancing the heat transfer performance of oscillating heat pipes in horizontal mode, wettability gradient surface with nano-grass structure was prepared with a gradient of contact angles from 0°to 83.8°from the evaporation section to the condensation section by controlling chemical etching time, and introduced into oscillating heat pipes. Six-turn flat plate oscillating heat pipes were investigated visually and experimentally under different filling ratios, heat input and orientations. The results demonstrated that wettability gradient surface oscillating heat pipe showed slightly better thermal performance than bare copper oscillating heat pipe in vertical heating mode. While in horizontal heating mode, there were great improvement in both startup and heat transfer performance of the wettability gradient surface oscillating heat pipe due to its additional wettability-driven effect and more backflow liquid compared with bare copper oscillating heat pipe which scarcely started up and showed severe dry out. The amplitudes of the vapor-liquid interface, the oscillating instantaneous velocities, and thermal performance were significantly improved in the wettability gradient surface oscillating heat pipe compared with bare copper oscillating heat pipe. The maximum reduction of thermal resistance of wettability gradient surface oscillating heat pipe was 45% at the filling ratio of 50%.