Regulation of gas-liquid stratified flow boiling dynamic instabilities in horizontal tube: Effects of heat load distribution and wall thermal capacity

In this work, an experimental investigation on the regulation of gas-liquid stratified flow boiling dynamic instabilities was carried out in a 1530 mm long horizontal arranged copper tube with an inner diameter of 12 mm. Two different thermal boundary conditions, namely (i) heat load distribution, (ii) wall thermal capacity were investigated. Three different heat load distributions (uniform heating, power decrease and power increase) and three kinds of tube with different thickness of graphite casing tubes (bare, 6 mm and 12 mm) were analyzed, respectively. The results showed that the oscillation intensity of gas-liquid stratified flow boiling dynamic instabilities was highly related to occurrence of the onset of nucleating boiling (ONB). In comparison with the based cases, the power increase heat load condition especially that with lower inlet subcooling degree and the case with thicker graphite casing tube had delayed the occurrence of ONB. And finally a suppression of dynamic instabilities was obtained. On the contrary, an early occurrence of ONB and an enhancement of gas-liquid stratified flow boiling instability were obtained for the other two cases.