Experimental study on sub-cooled flow boiling heat transfer in inclined non-uniform heating tube bundle channel

Abstract

Since the specific structure of the U-tube, non-uniform heating (NUH) occurs on the shell side of the U-tube steam generator or exchanger. When the above equipment are applied in ocean environments, they may be in an inclined condition. The coupled conditions of NUH and incline can enhance the complexity of the heat transfer on the shell side, especially in terms of the sub-cooled flow boiling, during which the heat transfer mechanism changes. In this paper, sub-cooled flow boiling in a tube bundle channel under the coupled conditions of NUH and incline are performed experimentally. The result shows that the Gungor-Winterson correlation is in good agreement with the experimental data under uniform heating (UH) conditions and the mean relative error is only about 10.05%, while the predicted ability is poor under the coupled conditions of NUH and incline. The heat transfer characteristics are affected by radial heat and mass transfer, convective flow, bubbles behavior, and bubbles migration, which are introduced by the coupled action of NUH and incline. At last, an improved Gungor-Winterson correlation is proposed for UH, NUH, and inclined NUH conditions. Its average relative error is only 5.56% in total, and less than 0.91% of data has a larger deviation than 15%.