ABSTRACT
As the surface temperature of a heater is increased in nucleate boiling, heat flux increases and reaches a maximum. If heat the surface with the heat flux beyond the maximum, transition from nucleate boiling to film boiling takes place. The maximum heat flux that can be obtained with nucleate boiling is called as critical heat flux (CHF). The effect of gravity level on CHF was investigated by Merte and Clark who conducted a transient cooling test in liquid nitrogen at reduced gravity using a copper sphere with 25.4 mm diameter. In high heat flux nucleate boiling, evaporation from the part of triple contact line at the nucleation sites plays an important role in heat transfer. Surface roughness, wettability, and thermal properties of the heater affect CHF. There are other secondary factors of CHF that connect to the fluid motion, i.e., the size and the geometry of the heater.
