A simulation study on the condensation flow and thermal control characteristics of mixed refrigerant in a dimpled tube

Abstract

In this study, the condensation flow and heat transfer characteristics of ethane/propane in the dimple tube have been numerically investigated, and the liquid droplet entrainment caused by the dimple structure was considered. The effects of operation and structure parameters on flow and heat transfer were analyzed, including different dimple depths, helical pitch, and dimple pitch. The results showed that the dimple tube had a higher heat transfer coefficient compared to the smooth tube, which increased with the increase in the mass flow rate and the decrease in the saturation temperature. The effect of dimple depth on heat transfer is greater than that of the dimple pitch or helical pitch, and the dimple depth will cause the local mass transfer rate to increase under high vapor quality. Meanwhile, the existing heat transfer correlations for smooth tubes were compared, and a condensation heat transfer correlation suitable for the mixed refrigerant in the dimple tubes was proposed with an average deviation of 6.3%.The conclusions obtained can provide support for the optimization design of liquefied natural gas plants.