Study On Numerical Simulation Of Gas-liquid Two-phase Flow And Heat Transfer Of Shell Side In A Shell-and-tube Heat Exchanger

Heat exchanger requiring a large investment has been extensively applied in the relative areas and the shell-and-tube Heat Exchanger, by its unique merits, became one of the most common heat exchange equipment. However, almost a half at shell-side in heat exchangers characterize two-phase flow and phase change and heat transfer, and the randomness of two-phase flow makes its heat transfer coefficient and the pressure drop at the shell-side unpredictable. The study on the two-phase flow and heat transfer of the equipments is of vital significance in improving the efficiency of exchanging heat.Numerical-simulation methods are adopted in this paper. With the help of CFD and FLUENT software, the paper stimulates the two-phase flow and phase change and heat transfer by using different media fluids, one of which is the saturated steam and another is cooling water. Based on the characteristics of shell-side in the shell-and-tube heat exchangers, the paper writes User-defined Function (UDF) to describe the phase transition of quality and quantity through the use of the conversion formula. A turbulence model and a two-phase flow model are selected in this experiment. Compared the results from formula and numerical-simulation date, the result validates that the feasibility and accuracy of selected model. By analyzing the influence on the heat transfer coefficients and its pressure, the paper draws the conclusion that the effects on the heat exchanger of shell-side of shell-and-tube heat exchanger are different by using vapor (condensation heat transfer) and cooling water (boiling heat transfer) as different media, the heat coefficient in the vapor can be 2.9 times that in the cooling water.This study shows that the characteristics of the flow fields of shell-side in shell-and-tube heat exchanger and its effects on the heat exchange, and these will be provided some valuable references for the improvement of tube heat exchangers. Analyzing the results from the heat transfer coefficients and the pressure distribution, the study is of guiding significance to the reasonable selection of the flow medium at shell-side in shell-and-tube heat exchangers.