Research On Heat Transfer Characteristics And Through-flow Structure Optimization Of Flue Gas Evaporator

In the process of actively promoting economic sustainable development in the country,the waste heat recovery and utilization technology has been widely promoted,and the heat exchange performance and operating efficiency of heat exchange equipment were deeply concerned by the enterprises.Based on the problems of acid dew point corrosion present in heat exchangers and uneven heat transfer of heat exchanger due to uneven distribution of flue gas flow field,the boiling heat transfer characteristics of the flue gas evaporator components in the separated phase change heat exchanger and the current sharing design of through-flow structure were studied in this paper.According to the actual conditions of the project and the structure characteristics,the model of the flue gas evaporator was reasonably simplified.Based on the Realize k-? turbulence model and the mixed multiphase flow model,a phase change model based on the De Schepper source equation under pressure control was added to establish numerical method of fluid boiling heat transfer in the heat pipe.At the same time,based on the experimental objects and parameters studied in related literatures,the above numerical methods were used to simulate.The simulation results were compared with experimental data to verify the feasibility of the numerical model.Based on the establishment of the numerical model for the boiling heat transfer process of the flue gas evaporator,the influence of in-tube static pressure on the fluid boiling heat transfer process was analyzed.When considering the influence of in-tube static pressure,the fluid boiling heat transfer coefficient in the heat transfer tube gets larger.An increase in wall heating temperature,evaporation temperature,and tube length will enhance boiling heat transfer.The influence of various parameters on the boiling heat transfer characteristics in the tube was summarized,and the heat transfer temperature difference correction coefficient of the boiling heat transfer process under different tube lengths was proposed.Based on the study of physical properties of flue gas,combined with engineering examples,a calculation model of the flue gas through-flow structure was established.A numerical model of the flue gas flow in the flue duct was established using a porous medium model which was equivalent to the heat exchanger,Realize k-? turbulence model,and a basic control equation.The pressure drop of the heat exchanger obtained by numerical simulation was compared with the calculated value of the empirical formula.The maximum error is 8.86%,verifying the feasibility of the porous media model.Standard deviation of the flow field velocity and the improvement coefficient of regional velocity distribution were used as evaluation parameters,to evaluate the uniformity of flow field velocity distribution in the flow structure under different panel elevation angles and deflector numbers.The effect of different deflector numbers on the uniformity of flow field velocity distribution in the through-flow structure under changing conditions were analyzed.The simulation results show that reducing the elevation angle of the panel and increasing the number of deflectors can effectively improve the uniformity of the flow field velocity distribution.This paper focused on the analysis of the influence of different factors on the boiling heat transfer characteristics in the heat transfer tubes under consideration of Intra-pipe static pressure.At the same time,this paper studied the influencing factors of the flow field distribution on the heated surface and how to improve it on the basis of ensuring the heat transfer characteristics of the heat exchanger,in order to achieve the greatest degree of waste heat recovery.And it has important guidance and reference significance for improving the economic efficiency of enterprises in practical projects.