Numerical Simulation Of Flue Gas Condensation Heat Transfer In The Tail Of Natural Gas Boiler

Traditional coal-fired boiler for the environment pollution is serious,gas boiler is the country in recent years to promote clean burning,reduce the pollution of coal-fired boiler for the environment,emerged in the gas boiler,due to the natural gas of main composition is methane,the main products of combustion is water and carbon dioxide,so smoke contains lots of saturated steam and saturated steam in the process of temperature decreases gradually,when dropped to the dew point temperature,can release the huge latent heat,if this heat is not effective recycling,not only caused the greenhouse effect,causes the waste of energy.This part of heat recovery can improve the utilization rate of natural gas,therefore,this paper studies the gas boiler tail condensation heat transfer process.Before gas boiler,without the economizer,under the condition of waste heat recovery exhaust temperature up to 180 ? above,in the study of this topic,first of all,finned tube heat exchanger design calculation,on the basis of the combustion,by analyzing the composition of natural gas,it is concluded that natural gas components of the products of combustion in boiler,to a greater degree of absorption in the recovery of waste heat in flue gas,selects the high heat transfer efficiency,compact and lightweight,strong adaptability of finned tube heat exchanger as economizer expansion feature research,fully considering the symmetry boundary conditions,and the physical model was simplified reasonably,SolidWorks is used to establish a three-dimensional physical model of finned tube heat exchanger.Gambit was used to divide the grid,and fluent software was used to simulate the condensation and heat transfer process of flue gas in finned tube heat exchanger.This paper obtained by numerical simulation in the flue gas in the fin heat exchanger of the temperature field,velocity field,pressure field,and condensatevolume fraction distribution,and by changing the flue gas velocity,fin spacing,fin thickness,fin height,adopt the method of control variable to explore the optimal structure parameters,to optimize,the study found that as the structural parameters,flow around the intensity and location of all different,flow around sharp,because will produce larger disturbance,strengthen heat transfer,the structural parameters,the flue gas condensation occurred in the finned tube heat exchanger position is different,the effect of condensation is different also,Through analysis,it is concluded that within a certain range,the flue gas velocity and fin height have the largest influence on the heat transfer of flue gas condensation,followed by the fin spacing,and the fin thickness has the smallest influence on it.Through comprehensive heat transfer analysis,it is concluded that the heat transfer performance is the best when the finning ratio is within the range of 4.48 to 5.21.The research results have certain guiding significance for improving the heat exchange efficiency and design of finned tube heat exchanger.