OPTIMIZATION OF PULSATING HEATING IN POOL BOILING

This paper describes an experimental and theoretical study of the peri odic on and off heating of water on a horizontal surface. The heat tra nsfer is effected by natural convection and isolated bubbles. The expe riments cover the heat flux range 33-154 kW/m(2) and the wall excess t emperature range 7-13 degrees C. It is shown experimentally that the c ycle-averaged thermal conductance between the surface and the pool can be maximized by properly selecting the time intervals of the on and o ff heating cycle. The maximum relative augmentation of the thermal con ductance is approximately 15 percent. In the second part of tile study , an order of magnitude analysis shows that the cycle-averaged thermal conductance can be maximized analytically by considering only the sin gle-phase natural convection effect, and that the optimal time interva l when heating is ''on'' agrees with the experimental results.