Study On The Performance Of GAS Water Heater Based On CFD

The research object of the paper is heat exchanger which is the core component of gas water heater.First,the paper analyzes the heat transfer process of gas water heater which are made by the copper fin tube heat exchanger.On this basis,the paper analyzes the internal fluid flow and heat transfer conditions of copper fin tube heat exchanger through numerical simulation and puts forward opinion to improve its structure.Further to improve gas water heater performance and reduce the production cost,the paper designs a kind of herringbone corrugated flat tube heat exchanger which made by stainless steel,and prove it is feasible in theory through numerical simulation.The paper mainly do the following work:(1)With simplified model reasonably,the paper analyzes the internal fluid flow and heat transfer conditions of copper fin tube heat exchanger through CFX and find that there are vortex area in the wind pipe surface which will weaken the heat transfer.For reduce this situation,the improvement opinion is punching in this area or changing for the convex shape.Besides the paper also study the impact on the thermal efficiency by fin thickness, fin spacing and tube diameter and estimate their Value range and point out that the influence of fin spacing is the largest.(2)The paper designs a kind of herringbone corrugated flat tube heat exchanger which made by stainless steel and determine its structural form Preliminary. Through numerical simulation,the results show that the herringbone corrugated strong heat transfer,but it also makes the fluid form a larger vortex area in part of areas which will weaken the heat transfer.In order to solve this problem,the paper proposes two improvement program that is increasing the slot width and changing into trapezoidal groove.Trapezoidal groove can improve the flow and heat transfer conditions,but the same time due to the extension of heat exchange area is reduced,the heat exchange efficiency ascension is not big.When increasing groove width to1.5mm,it will have an stronger heat transfer effect.(3)The results of simulation on herringbone corrugated flat tube heat exchanger are that thermal efficiency is85.24%,temperature rise is2℃,exhaust smoke temperature is192℃.It has reached the national standard,which proving it is feasible in theory.Compared with the copper fin tube heat exchanger,it can improve performance of heat transfer,and can reduce the production cost.