Studies on temperature-controlled pool-boiling heat transfer

A new computer-controlled experimental system to realize the stable temperature-controlled operation in nucleate, transition and film boiling regions was developed. By using this system, characteristics of temperature-controlled pool-boiling heat transfer covering nucleate, transition and film boiling regions was studied for a platinum wire heater in water at atmospheric pressure. Effects of subcooling, heater orientation, heater dimension, heater surface contamination and of surface active agent were studied. Thermal hysteresis effects by increasing and decreasing heater temperature were found, for the first time, both in the nucleate boiling region and in the transition boiling region near the maximum heat flux point. Maximum heat flux of nucleate boiling and maximum heat flux of transition boiling were not the same. Artificial contamination on the heater surface and slight addition of surface active agent in water both severely influenced the transition boiling heat transfer. It was confirmed that the transition boiling was the combination of nucleate and film boiling. (auth.)