Study On The Flow And Heat Transfer Characteristics In Regenerator

Stirling Engine is being payed more and more attention nowadays because of its abroad fuel adaption and good environmental character, whose most important component is regenerator. The working condition of regenerator is very complicated and bad,and even the Stirling Engine is working constantly ,the working parameters of regenerator are changing instantaneously.Because it works at oscillating pressure and velocity conditions.So the numerical simulation about regenerator is welcomed by a lot of people.With regard to the problem of heat transfer in regenerator, there are two models: local equilibrium model and non- equilibrium model. Equilibrium model assumes that the solid matrix and the fluid are in thermal equilibrium at each spatial location within the porous medium, and are one energy equation model; Non-equilibrium model is two-energy-equation model, which caculates energy equation of fluid and solid separately, and can make precise simulation on temperature of fluid and solid. But because of the complication of Non-equilibrium model, the thermal Non-equilibrium porous-media model presented is considered to be an initial, or"draft"model.Some parameters and correlations are gained from experimentation, so there are some errors. Regenerator working at strong pulsating condition, and temperature within it is changing sharply. There is violent heat transfer phenomenon between fluid and solid matrix, so Non-equilibrium model in simulation of regenerator is very important.This thesis adopts Darcy-Brinkman-Forchheimer model to calculate the flow in regenerator, compares with experiment results,and finally has gained resistance coefficient model fitted for the regenerator.This thesis adopted both thermal equilibrium porous media model and non-equilibrium porous media to simulate the heat transfer process in regenerator, gained the velocity distribution,temperature distribution , pressure distribution, and changing circs of each flow parameter with time,simulated the flow and heat transfer in regenerator under different inlet velocity of gas, different pulsating frequency,different porosity, and gained the synthesis parameter of regenerator—thermal efficiency.This thesis induced the influence of all the above condition to the regenerator capability.The investigation in this thesis indicated that the thermal non-equilibrium packed-bed porous model can simulate the flow and heat transfer process exactly in regenerator, can calculate the violent heat transfer between gas and solid matri–x, and simulated the"thermal sponge"function of regenerator intuitively that the solid matrix discharges thermal during cool fluid in period and sucks thermal during hot fluid in period.These make up the difficulty of experiment mesurement in regenerator.