| Energy is the basic material conditions of human development,severe energy situation calls for the development of energy conservation and new energy.Today’s energy crisis and environmental pollution have become two of the social development problems,and energy storage technology can ease the contradiction between energy supply and demand mismatch,which is one of the most effective ways of energy saving and emission reduction.Phase change energy storage due to its energy density,heat temperature changes little and it’s easy to control,and then became one of the most promising storage technologies.Meanwhile,the efficient implementation of phase change energy storage can’t achieve without thermal storage performance of phase change materials and heat transfer performance of storage devices.This paper has studied a plate-type phase change energy storage heat exchanger,establish a mathematical model of the heat transfer process,use Computational Fluid Dynamics(CFD)theory and numerical simulation of the plate-type structure of heat exchanger under the same conditions with different geometric parameters on heat transfer performance.Reached after comparing an optimal model of performance required to satisfy the given condition,and manufacture a heat exchanger based on the model,built an experimental platform for experimental investigation.The research results have a guiding role for phase change energy storage heat exchanger design and optimization.The specific studies and conclusions are as follows:1.Check out literature and combine the condition,this paper has chosen 64th paraffin as phase change material(PCM)for research.The phase transition temperature of this PCM is 64℃,isotropic,thermal performance stable,no toxic corrosive,and without undercooling,which is suitable as a PCM for the research;2.Design a heat exchanger of plate-type structure,taking into account the effects of geometric parameters of performance of the heat exchanger,use control variables,design 9 different geometrical size of heat exchanger models,and use Fluent software numerical simulation those heat exchanger models.Research shows that,in the context of geometric parameters of this paper,in the case of dHTF as constant,larger dPCM of heat exchanger can store more energy and get more stable thermal output,but the storage rate will be slow,smaller dPCM of heat exchanger storage rate more quickly;in the case of dPCM as constant,larger dHTF of heat exchanger,the rate at which heat energy faster,but can not get a stable heat output,smaller dHTF of heat exchanger heat output more stable.Considering the storage rate and stability of output,this paper has chosen M4(dHTF=10,dpcM=15)as the optimal model,in this model the PCM completely melted when t-12h,energy release continued about 30min with stable output of 61’C hot water,then reference on the optimal model manufacture a heat exchanger for experimental study.3.Manufacture a heat exchanger and built an experimental platform for experimental investigation.In the energy storage experiment,the PCM melted trend as in numerical simulation,and costs the same time as in numerical simulation.In the energy release experiment,the outlet fluid temperature trends over time also match the numerical result.By analyzing the outlet fluid temperature trends over time found that,the three stages of energy storage/release is clear,and consistent with the trend of numerical simulation.In experiment,exporting hot water with an average temperature of 55℃,the numerical simulation of exporting hot water with an average temperature of 610℃,error is 9.84%,can meet the conditions of living water. |
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