Numerical Simulation On The Working Pocess Of Gas Water Heater

Noises will bring gas water heater users a lot of inconvenience,including concerns about the product,fear generated in the process of using and so on.In addition,there will be security risks in the gas heaters which makes noises in a long time without repairment.So research on the noises will be of great significance.Gas water heater noise is mainly affected by the following four aspects,namely,mechanical vibration,fluid flow,gas mixture combustion and gas dynamics.This article is working on building a numerical simulation model of the gas water heater,analyzing the oscillation of combustion chamber pressure,and analyzing the causes of combustion noise from the point of the combustion gas mixture.This study is based on our previous work and this article is to perfect and improve our previous simulation model.Our previous work established the model of gas water heater during steady state,this article is mainly focused on the combustion chamber and the exhaust system model.Firstly,the combustion process in the combustion chamber has been studied,and then propose the idea of a two-region model,analyze the height of diffusion flame and the injection movement in the burner.And propose a hypothesis on the combustion pressure and combustion temperature in order to establish a steady-state model of the combustion chamber.Secondly,contact to the actual working process of the water heater,establish a transient model of the combustion.But the transient model should be added a time delay,there is a reasonable analysis to add the delay.Thirdly,using FLUENT to analyze the flow of flue gas in the exhaust system,combine the result of traveling-wave method and FLUENT,to verify the correctness of the model.Finally,add filter to build a steady-state model and a transient-model of water heater.To verify the justifiability of the two model,combine the experimental results and the simulation results in twelve simulated working conditions.After analyzing the simulation results,the difference between the phase of the combustion heat and the phase of chamber pressure is less than ? / 4.Constantly pressure oscillation in combustion can be explained by the Rayleigh criterion.Analyzing on pressure oscillation frequency,the study found that it is unrelated to helmholtz effect,it's related to time delay.