Numerical Simulation On Condensation Heat Transfer In Shell Side Of Double-inlet Condenser

The object of this article is a double inlet condenser,and the double inlet condenser is optimized and reformed on the basis of the traditional surface condenser.The dual inlet condenser has two steam inlets that receive the exhaust steam from the two steam turbines,respectively.Due to the presence of two steam inlets,the internal flow and heat transfer conditions are more complicated than conventional condensers.Therefore,there is a strong engineering application value to study the internal flow and heat transfer characteristics of the dual inlet condenser.At present,the domestic and foreign research on the condenser mostly adopts two-dimensional numerical simulation or quasi-three-dimensional numerical simulation,which can not fully reflect the three-dimensional characteristics of condenser flow and heat exchange.In this paper,Fluent software will be used to conduct full three-dimensional numerical simulation of the condensation heat transfer process of double-inlet condenser shell.In this paper,the mathematical model describing the condensation heat transfer inside the condenser and the UDF are established first,and a surface condenser is numerically simulated.The simulation results are compared with the experimental data to verify the correctness of the mathematical model and the UDF.Then according to the structure and the operating parameters of the double-inlet condenser,the relevant program statements in the UDF are modified to perform full three-dimensional numerical simulation of the double-inlet condenser operating under design conditions.The spatial distribution of the important parameters of the condenser shell is analyzed.On this basis,a series of numerical simulations were performed on the inlet temperature of cooling water,the flow of main and auxiliary steam,the concentration of non-condensable gas and the thickness of fouling on the inside of the pipe wall by using the control variable method.The influence of the above four factors on the flow and heat transfer characteristics of double-inlet condenser shell is obtained.The inlet temperature of the cooling water increases,the flow rate of the mixed gas in the condenser decreases,the condensation rate decreases,the vapor resistance increases,the back pressure of the steam inlet increases,the steam flow decreases,the heat load of the condenser decreases,the flow rate of the mixed gas decreases,and the vapor resistance When the pressure is reduced,the back pressure at the inlet decreases;the increase in the concentration of non-condensable gas increases the uncondensed vapor and non-condensable gas in the condenser,hindering the flow of the mixed gas inside the condenser,and the concentration of non-condensable gas.The slight increase will cause great damage to the heat transfer effect of the double inlet condenser;the increase of the thickness of the dirt layer will increase the steam resistance of the condenser rapidly,the back pressure of the air inlet will increase,the heat resistance of the heat transfer will increase,and the steam will increase.The heat transfer effect of the cooling water becomes worse,and the steam condensation amount decreases,which has a serious impact on the performance of the condenser;when the steam inlet angle at the upper side increases,the average flow rate of the mixed gas,the back pressure at the top steam outlet,and condensation Both the vapor resistance and the average air concentration decrease with increasing inlet angle.When the inlet angle exceeds the critical value,these parameters increase with the inlet angle.