Research On Flow And Heat Transfer Characteristics Of Stirling Engine Regenerator

Stirling engine is one of the most promising devices in the field of renewable energy such as solar energy and biomass energy because of its high efficiency,compact structure and low noise.Regenerator is the core component of Stirling engine,which plays an important role in the whole system.The performance of the regenerator has a significant impact on the overall efficiency of Stirling engine,so the research on regenerator has been obtained more and more attention in recent years.Due to the high temperature inside the regenerator,the influence of radiation on the heat transfer inside the regenerator cannot be neglected.In this thesis,the heat transfer model considering the influence of radiation was put forward and simulated by FLUENT15.0 software.The results show that the pressure and temperature distribution of the regenerator are similar to those without radiation.The working fluid temperature increases by considering the radiation effect in the regenerator.And for materials with a small thermal conductivity such as stainless steel,the effects of radiation will be greater,so the radiation effects inside the regenerator should not be ignored.Considering the radiation,the effect of the metal mesh structure and the properties of the metal mesh on the performance of the regenerator were carried out by numerical simulation for optimizing the regenerator.The results show that when the mesh count N is constant,the diameter of mesh changes,the radiation effect has the greatest influence on the comprehensive performance of the regenerator,and its comprehensive performance parameter Rosc is the largest.Therefore,changing ds is the most effective way to increase the regenerator efficiency.The influence of specific heat capacity on the performance of regenerator is also studied,with the specific heat capacity increases,Rosc first increases and then decreases,and there exists an optimum Rosc at which the comprehensive performance of regenerator is the best.In this thesis,the performance of screen regenerator with uniform decreasing porosity was calculated.The results show that the regenerator with variable porosity screen has small internal flow resistance and high average temperature compared with the regenerator with constant porosity.And the change of temperature near the hot end is more obvious and the overall performance of the regenerator is improved.At the same time,it can be found that there is no sudden change in temperature due to no obvious delamination boundary of the screen with variable porosity,which is beneficial to reduce the thermal stress loss of the regenerator.