喷雾冷却发热壁面温度非均匀性实验研究

Experimental study of temperature non-uniformity on spray cooling surface

喷雾冷却是一种新型的高热流密度换热方式,利用可视化手段对喷雾冷却中发热体壁面温度非均匀性进行了实验研究。采用热电偶多点测温及红外成像相结合的方法测量发热体壁面温度,通过分析提出了温度不均匀度现象;结合壁面液膜特性及多普勒激光测速仪所测之液滴参数的空间分布,分析阐述了温度非均匀现象的成因与影响因素。研究结果表明,发热壁面温度的不均匀来自于喷雾特性的变化,通过选择合适的喷雾高度使工质从壁面中心向四周附壁流出,可以克服喷嘴空心回流区影响、增强壁面中心的换热,使发热壁面温度更均匀、同时提高冷却效果。本文突破了将壁面温度分布视为均匀的传统观点,为喷雾冷却的性能评估提供了新的途径,对喷雾冷却特性进一步的科学研究和工程应用具有参考价值。

Spray cooling is a new type of high heat flux heat transfer, Surface temperature and internal distribution of the heating cooper rod were discussed and studied in this paper which adopts visualization tools. A multi-point thermocouple and a infrared＇ imaging device was applied to measure the heating surface temperature, The conception of temperature uneven degree was put forward through the analysis of spray cooling experiment which was carried out in a series of spray height and heat flux~ and the cause of temperature uneven degree and its influencing factors were presented by combining with special distribution of the droplet parameters measured by Doppler PDA and liquid-film characteristics. The results show that proper spray height can improves the utilization efficiency of the working medium , cool the surface evenly, and enhances heat transfer. This experiment breaks through the traditional opinion that the surface temperature is uniform, providing a new approach for the performance assessment of spray cooling, a reference for establishment of technology standards and evaluation of heat transfer performance of spray cooling, and has a guiding significance for the science research and engineering application of the spray cooling.