Development of measurement technology for surface heat fluxes and temperatures

Liu, W.; Takase, Kazuyuki

A system for measuring the surface temperature and the surface heat flux of a heating block was developed that has no need for a sensor set on the surface. The system consisted of two parts: (1) inner block temperatures were measured using micro-thermocouples; (2) using the measured temperatures, an inverse heat conduction problem was solved to get the surface heat flux and surface temperature. For the inner block temperature measurement, special T-type micro thermocouples with a common positive pole were developed. A total of 10 thermocouples were set at a depth of 3.1 m beneath the boiling surface, in a circle with a radius of 5 mm. The developed system was used to measure the change of surface heat flux and surface temperature in a pool nucleate boiling process. Experiments were performed at atmospheric pressure. The experiments showed that the developed special T-type micro thermocouples can successfully measure the temperature change in a boiling process. By using the measured temperature, a semi-infinite inverse heat conduction problem was solved to get the surface heat flux and surface temperature. The change in surface heat flux and surface temperature in a bubble cycle was derived.