Numerical simulation on the flow and heat transfer characteristics in the one-side heating helically coiled tubes

Abstract

The circumferential heat flux often distributes non-uniformly in the heat exchange tubes, such as the coiled tubes water cooled wall in power plant boilers and the special heat exchangers used in the chemical reaction process. To study the thermal hydraulic characteristics of the flow in the helically coiled tube under different heating conditions, numerical simulations are conducted in tubes with uniform and one-side heating (7191⩽Re⩽47923, 0.983⩽Pr⩽6.992). The simulation results show that, compared with the case of uniform heating, the temperature difference between the outer side and inner side becomes more significant; The average volume fraction and the pressure drop of the two-phase flow are both lower. The local heat transfer coefficient mainly depends on the vapor distribution. The distribution of heat transfer coefficient around the cross-section is different in uniform and one-side heating tubes. The heat transfer coefficients around cross-section are found to display a “W” shape in uniform heating tube, but an “M” shape in one-side heating tube. Eventually, the differences of the average pressure drop and heat transfer coefficient under the two heating conditions are all lower than 15% within the present working conditions.