Experimental study on the Onset of Nucleate Boiling in a narrow rectangular channel under transversely non-uniform heating

Many researchers have investigated the Onset of Nucleate Boiling (ONB) in a narrow rectangular channel. The power released from the edge of plate-type fuel is higher than the middle of plate-type fuel. Al-Yahia et al. investi-gated the effect of transverse power distribution on the subcoold boiling in a narrow channel. They found different thermal-hydraulic characteristic between non-uniform and uniform power distribution. Thus, non-uniform heating must be considered in research reactors which use the plate-type fuel. The objective of this experimental study is to find the effect of transversely non-uniform heating on the ONB. The effect of transversely non-uniform heating on the ONB in a narrow rectangular channel is studied. The experiments under non-uniform and uniform heating are performed, and the results are compared. The thermal power at ONB is decreased under non-uniform heating. Since the non-uniform heating causes the local high heat flux and wall temperature, ONB occurs at relatively low thermal power compared to uniform heating condition. The local heat flux and wall temperature at ONB under non-uniform heating are similar with the results of uniform heating condition. Since bubble generation is depends on the local condition, under the same system condition, the non-uniform heating has no effect on the local heat flux and wall temperature at ONB.