DEVELOPMENT OF A NEW DEVICE TO MEASURE LOCAL HEAT-EXCHANGE BY EVAPORATION AND CONVECTION

According to the principles of heat and mass transfer, the rate of local heat exchange by convection (C) and local heat loss by evaporation (E) can be estimated if temperature and vapor concentration profiles in the boundary layer are measured. In addition, temperature (Ts) and vapor concentration (rho-s) at the surface may be predicted from the measured profiles. On this basis, a new device was developed to measure parabolic profiles by incorporating three relative humidity sensors coupled with thermistors into its probe. It has been evaluated from various tests including human experiments. The results showed that the device, with humidity sensors arranged perpendicular to the surface, could estimate C, E, Ts, and rho-s in closer agreement with direct measurements when compared with the conventional gradient method. This confirmed that our method had clear advantages over the conventional gradient method under laminar air flow conditions.