Numerical Simlllation Oin Heat Transfer Characteristics Of Regenerative Heat Exchanger

The heat and power cogeneration units in heating season generally adopt the operation mode of "ordering power by heat",and the power load is limited by the heat supply,as a result,the peak load regulation capacity of generating units decreases and the generation load of renewable energy such as wind and solar energy is squeezed out,resulting in a serious phenomenon of wind abandonment and light abandonment.In this paper,a new type of regenerative heat exchanger is designed,which not only keeps the quality of heating,but also enhances the heat storage capacity of cogeneration units.It can make "decoupling heat-power",improve the peak shaving capacity of cogeneration units,and leave more space for renewable energy generation.Firstly,a regenerative plate heat exchanger and a double-layer regenerative shell-and-tube heat exchanger are designed.Regenerative plate heat exchanger encapsulates phase change material between two heat exchanger plates as phase change heat exchanger plates.The lower layer of double-layer regenerative shell-and-tube heat exchanger is a heat transfer process,and heat transfer between the cold and hot fluids is in progress through the wall of the tube.The upper layer is a heat storage process.The superfluous heat of the hot fluids is absorbed by the heat storage medium and stored in the latent heat of phase change.When the heat load is low,the heat storage medium solidifies and releases heat to maintain the cold fluids’temperature to a certain extent.It can not only make the cold fluids reach a certain temperature rise,but also reuse the heat source and improve the heat transfer efficiency of the heat exchanger.The basic part of regenerative plate heat exchanger and the phase change region of the double-layer regenerative shell-and-tube heat exchanger is selected as the regenerative heat transfer unit,and the model is built.This paper uses Fluent software to simulate the heat storage and release process of the regenerative heat transfer unit and the control variable method is used to simulate the heat transfer characteristics of regenerative heat transfer unit by changing the flow rate of heat transfer fluid,the number and thickness of fins,the thermal conductivity of phase change material and the thickness of phase change material.The results show that increasing the thermal conductivity of phase change layer and changing the flow rate of heat transfer fluid play a great role in enhancing heat transfer of regenerative heat transfer unit and increasing phase change layer thickness can prolong the time of maintaining the outJet temperature of heat transfer fluid during exothermic process.Finally,the heat storage and release process of double-layer regenerative heat exchanger unit is simulated.It can be seen that adding heat exchange layer can effectively ensure the heating quality of regenerative heat exchanger.The future research work on regenerative heat exchangers is prospected.