Characteristics of Boiling Curve in Transition Region between Nucleate Boiling and Film Boiling

An experimental study has been carried out for estimating surface temperature and heat flux during a transient heating process from nucleate boiling to film boiling and a inverse process including nucleate boiling region at atmospheric pressure using newly developed inverse solution. Three different materials of gold, copper and brass are employed to make the effect of thermal properties on the boiling curves in the transient region including both ends, which correspond to maximum and minimum heat fluxes. It is found that the histories of surface temperature and heat flux for the transition boiling region during either heating process or cooling process can be traced well. The experiment shows that the histories for the heating and cooling processes are different in the transition region while these are overlapped in the nucleate boiling region except that the maximum heat fluxes reached during heating and cooling processes are much different. It is found that the histories for the heating process are little influenced by the thermal properies, while these for the cooling process are much affected.