| Energy shortage has always been an urgent problem hindering the rapid development of human economy and society.Promoting the optimization of the energy structure and accelerating the large-scale development and utilization of renewable energy and clean energy are of great significance for promoting the rapid and stable growth of the global economy.Energy shortage has always been an urgent issue that hinders economic globalization.Promoting large-scale development and utilization of renewable energy and clean energy is an effective means to promote the rapid and stable growth of the global economy.Phase change energy storage technology is an effective means to solve the mismatch/imbalance in the process of supply and demand of clean energy and improve energy utilization efficiency.In addition,phase change energy storage technology has been widely used due to its highly energy storage density,constant temperature and easy process control.However,phase change materials have poor thermal conductivity,which greatly hinders the efficient storage and release of heat in the entire energy storage system.Adding fins is the most simple,safe and reliable method to improve the low thermal conductivity of phase change materials and the heat transfer rate of phase change energy storage device.Based on the computational fluid software Fluent 15.0,the structural parameters of the developed cavity type embedded U-tube energy storage unit is optimized.the phase transition temperature is 36.23-41.25?modified paraffin as phase change material,in view of the heat storage unit cooling time is long,heat transfer rate in the solidification process of problem,add the ribbed reinforcement/heat storage performance of the heat storage unit.Water and air has used as Heat Transfer Fluid?HTF?in heat storage and heat dissipation processes,respectively.By means of numerical simulation,the influence of structural parameters?heat dissipation distance and unit height?of heat storage unit on heat dissipation performance was investigated.The influence of changing the air inlet temperature on the solidification process of the heat storage unit was analyzed under the optimal structural parameters of the heat storage unit.In addition,the experimental platform was built to test the performance of the heat storage unit,and the effect of fin addition on the melting and solidification mechanism of PCM in the storage/cooling process of the energy storage unit under specific operating conditions was compared and studied.The effects of the number of fins,fin height,thickness and distribution method on the thermal performance of the regeneration unit during the solidification process were studied,respectively.The results show that,for the heat storage process,the addition of fins can enhance the heat transfer,but it can inhibit the natural convection to some extent.For the heat dissipation process,the addition of fins has an obvious strengthening effect on the solidification process of the heat storage unit.The addition of fins can effectively enhance the release of heat in the latent heat release phase.The temperature distribution of the energy storage unit with fins is more evenly in the process of heat storage or heat dissipation and has better heat transfer performance.In addition,in the pr ocess of heat dissipation,the lower the ambient temperature,the greater the heat transfer temperature difference,the faster the heat dissipation;The higher the fin height and thickness,the shorter the heat dissipation time.The smaller the fin spacing is,the larger the effective heat transfer area is,which is more beneficial to heat dissipation.When the fin thickness is 2mm and the number of fins is 5,the comprehensive performance of the heat storage unit is the best.In addition,the forced convection also has an obvious strengthening effect on the heat dissipation process.When the wind speed is 6m·s-1,the complete solidification time of the heat storage unit is 14h,which is 69.57%stronger than that of the natural convection heat dissipation. |
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