Research On Condensation Heat Transfer Method Used In Deep Recovery For The Residual Heat Of Flue Gas From Natural Gas Boilers

In the natural gas boiler,exhaust smoke temperature is higher and exhaust heat loss is bigger.Overheated vapor along with smoke goes into the atmosphere which will cause a huge waste of vapor latent heat.Exhaust smoke temperature is higher in the natural gas boiler.Therefore,it is an urgent issue to be solved that is of vapor latent heat in the state of overheated recycle.With fine heat transfer performance,tube heat exchanger has other advantages at the same time,such as tight structure and easy cleaning.Therefore,it plays an important role in reducing exhaust temperature and recovering waste heat of flue gas among many methods.This paper aims to the issue of exhaust smoke temperature is higher in the natural gas boiler and of vapor latent heat in the state of overheated recycle.On the basis of combining engineering thermodynamics and related calculation of heat transfer theories,it equips with finned tube heat exchanger in the tail gas boiler system which deeply recycles sensible heat in the process of exhaust flue gas and latent heat released from vapor condensation.In order to achieve the goal of reducing the exhaust temperature and deeply recycling flue gas heat.In this paper,the physical model established by the analysis of its nature pattern,and the use of simulation methods to restore the actual situation.We compared the accuracy of simulation calculation results of finned tube heat exchanger according to previous experimental data,then validated that the method was operable.Derived the laws of condensation and heat transfer characteristics of the flue gas on the change of parameters of flue gas side entrance velocity,fin spacing,fin thickness and fin height and so on.These include:1.In the four parameters,i.e.the flue gas inlet velocity,the spacing,thickness,and height of the fin,the first parameter makes the most influence to the heatexchange,the fin spacing and thickness rank second and third respectively,and the fin height produces the minimal impact.2.When changing the gas side inlet velocity,with the increase of the inlet flue gas velocity,the average heat transfer coefficient increases,as well as the flow resistance,resulting that heat transfer performance is enhanced.The fin spacing and thickness decrease,and the average heat transfer coefficient and the heat transfer increase.When the height of the fin decreases,the average heat transfer coefficient and the heat transfer also decrease.Taking static payback period method to analyse the economic benifit with the finned tube heat exchanger.Natural gas boiler system running and to get the shortest economic recovery cycle.