Analysis Model Of Heat Transfer Characteristics And Heat Loss Of Regenerator For Stirling Cycle

Osicllating flow is a typical feature for Stirling engine with complex heat transfer and flow characteristics,which affect the heat distribution and thus,the heat loss of Stirling engine.An exact analysis of heat loss is one of the most significant basis on perfecting Stirling cycle analysis.Accroring to the existing study of Stirling engine heat loss,the regenerator contributes the most part of heat loss?more than 65%?.In this Study,the heat transfer characteristics and the heat loss of regenerator are analyzed by modelling a complete regenerator and simulating the heat transfer process numerically,which aims to perfect the Stirling cycle analysis methods and the design of Stirling engine.The unsteady temperature fields of unidirection and oscillation flows are analyzed and compared qualitatively.The influence of oscillation flow on heat loss is obtained.For wire mesh regenerator,the speed of heat transfer in the wall is much lower than that in the porous media,which results in the temperature difference and heat loss.The oscillation flow has effect on both axial and radial heat loss.The oscillation flow goes back and forth with long time,so the axial heat loss grows up with the increasing of time.The alternation of cold and hold flow will reduce the radial heat loss.Besides,the annular effect of oscillation flow is also a main factor of heat distribution,which can increase more than 20?of temperature difference.The influence of temperature,mass flow rate and frequency are analyzed quantitatively.The heat flux is affected mainly by convective heat transfer coefficient h and temperature difference?T.The impact of temperature can be described by temperature difference?T.The mass flow rate influences Re which is related to Nu,h and thus,the radial heat flux.Based on the theoretical analysis,the radial heat loss is related to Re and?T,which can be described by the correlations Q_?=6.24?10⁵+173.17 Re^0.66?35?T?unidirectionflow?andQ_?=-2.45?10⁴+0.14 Re?35?T?oscillation flow?.The impact of mesh porosity on regenerator heat loss is studied.When the porosity is larger,the characteristic flow rate and Re decreased which leads to weaker heat transfer.Thus,the heat loss will become smaller with larger porosity.The structure optimization is studied based on the impacts of mesh layout.When the average porosity is the same?similar Re?,putting lower mesh?20?on the hot side and putting higher mesh?100?on the cold side is helpful for reducing the radial heat loss.This layout can reduce 73.14%heat loss compared to putting 60 mesh directly.Finally,the method is discussed to apply the regenerator heat loss analysis to the Stirling cycle analysis.It can be an useful way to perfect 2^nd and 3^rd order analysis methods by considering the radial heat loss of regenerator and adding one source term?the correlations derived above?in the energy equation.