喷雾冷却的热逆转现象及其传热强化特性

针对高热流密度激光介质散热问题，利用实验方法研究了以十二烷基硫酸钠水溶液作为工质的喷雾冷却传热特性。结果表明，在特定的热流密度范围内，随着热流密度的增加，加热面温度不升反降，称之为热逆转。热逆转现象对对流换热系数的提升作用可高达94.0%，提升大小与热流密度有关。热逆转对应的热流密度区间为80～130 W/cm2，与浓度关系较小。热逆转现象与实验过程有关，该现象仅在热流密度逐渐升高的过程中出现，降低和任调热流密度过程中未发现此现象。热逆转具体原因还有待研究。

Heat reversal phenomenon of spray cooling and its heat transfer enhancement characteristics

Aiming at the requirements of the heat dissipation for high heat flux laser medium, an experimental platform was designed and built. The spray cooling of heat transfer enhancement experiment with different concentrations of sodium dodecyl sulfate aqueous solution as the working fluid was studied. The results show that within a specific range of heat flux density, as the heat flux density increases, the temperature of the heating surface does not rise but drops, which was named heat reversal. The heat reversal phenomenon increased the convective heat transfer coefficient by as much as 94.0%. The heat flux density range corresponding to heat reversal was 80?130 W/cm2, which had a weak relationship with concentration. This means that, in spray cooling, an increment in heat load can cause a temperature drop of the heated surface under certain circumstances. This phenomenon only occured when the heat flux density was gradually increasing, and it was not found in the process of reducing and adjusting the heat flux density. Surfactant boiling in the pool will also cause thermal reversal, but the specific reason remains to be studied.