Abstract:

Spray cooling is widely used in industries. Cryogen spray cooling has been implemented for the epidermis protection during laser surgery. For the improvement of cooling efficiency, the surface temperature was measured to calculate the surface heat transfer characteristics by the reverse heat conduction method. In order to investigate the influence of temperature measurement methods on the experimental result, a transient spray cooling rig was constructed to study the different heat transfer characteristics by using the thin film thermocouple (TFTC) fabricated by magnetron sputtering, the fine thermocouple (FTC) and the slice thermocouple (STC). The result suggested that the TFTC had the most sensitive thermal response, which can accurately reflect the temperature variation and corresponding heat flux. As for the FTC and STC, due to the limitation of indirect measurement, there was an obvious lag in temperature variation, which affected the subsequent analysis such as heat flux and apparent convective heat transfer coefficient. The employment of thin film thermocouple ensured the precise investigation of surface heat transfer during transient spray cooling, with reliable reference for clinical treatment.

Key words: spray cooling, surface heat transfer, temperature measurement, R404A

摘要：

喷雾冷却在工业过程中应用广泛，制冷剂喷雾是激光皮肤手术中实施表皮冷保护的必要手段。为提高冷却效率，需要通过表面温度的测量反推表面传热特性。为探索不同表面温度测量方式对实验结果的影响，搭建了瞬态喷雾冷却实验台，分别使用磁控溅射薄膜热电偶（TFTC）、丝状热电偶（FTC）和片状热电偶（STC）研究了R404A制冷剂喷雾环氧树脂表面传热特性的差异。实验结果表明，磁控溅射薄膜热电偶（TFTC）热响应性能最佳，能准确及时地反映表面温度的瞬态变化且可与热通量变化准确对应。丝状热电偶（FTC）和片状热电偶（STC）属于间接测温，温度变化存在明显滞后，影响热通量、对流传热系数等表面传热特性的精确分析。薄膜溅射热电偶测温是准确研究瞬态喷雾冷却表面传热过程的可靠手段，可为临床治疗提供理论指导。

关键词: 喷雾冷却, 表面传热, 温度测量, R404A