ABSTRACT
Boiling heat transfer is defined as a mode of heat transfer that occurs with a change in phase from liquid to vapor. There are two basic types of boiling: pool boiling and flow boiling. Pool boiling is boiling on a heating surface submerged in a pool of initially quiescent liquid. Flow boiling is boiling in a flowing stream of fluid, where the heating surface may be the channel wall confining the flow. There are several boiling regimes in pool boiling as well as in flow boiling. The only difference lies in the influence of flow effect. The buoyancy effect is significant in a pool boiling system, while flow forced-convection effect is significant in flow boiling inside a channel. Two-phase flows are classified by the void distributions. Basic modes of void distribution are bubbles suspended in liquid stream; liquid droplets suspended in vapor stream; and liquid and vapor existing intermittently. Boiling crisis is a combined phenomenon of hydrodynamics and heat transfer.
