TRANSIENT POOL BOILING HEAT TRANSFER FROM SMOOTH SURFACE DUE TO EXPONENTIAL STEP HEAT INPUT
Dynamic pool boiling of saturated distilled water due to exponentially increasing step heat input (q α eγ) on the smooth (Ra=0.106 µm) copper circular surface of 20 mm diameter is experimentally studied. The rate of exponential transient (γ) is varied from 1 to 6 at atmospheric pressure. γ=1 corresponds to quasi-steady heat supply whereas γ=6 corresponds to rapid heat supply. Effect of rate of transient on the onset of boiling (ONB) and fully developed nucleate boiling (FDNB) regime is studied. The existence of overshoot (OV) temperature and onset of boiling driven (OBD)
heat transfer is examined during various transients. High speed visualization technique is used to observe the ONB, bubble coalescence and FDNB at different rate of transient.