Influence of temperature measurement method on surface heat transfer during spray cooling

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.