Research And Optimization Design Of Casing Phase Change Energy Storage Floor Heat Transfer Model

The casing phase change energy storage floor is a new type of heating terminal technology which provides a possibility to solve the problem of mismatch between supply and demand in the solar heating process by storing solar radiation heat in the internal phase change energy storage material.In this paper,the phase change storage floor model was established,and the system was simulated by Trnsys software to analyze the thermal characteristics of the phase change storage floor heating building.The casing type phase change energy storage floor is mainly composed of casing phase change energy storage device and floor structure layers.The inner tube of the casing phase change energy storage device is hot water,and the phase change material is filled between the inner and outer tubes,and the storage and release energy of the phase change material is realized by heat exchange between the tubes.In this paper,a two-dimensional mathematical model of casing phase change energy storage floor was established by using the apparent heat capacity method.Based on the framework of Trnsys software,the casing phase change storage floor model Type178 and Type179were written by Fortran language.The accuracy and consistency of the model were proved by the error and consistency analysis of the experimental data and the simulated data.In order to study the thermal performance of the heating system of the casing phase change energy storage floor combined with solar energy,the system was established in Trnsys.The effects of tube pitch,phase change material layer thickness,melting and solidification temperature,and solar collector area on the thermal performance of the system were analyzed by single factor test.Taking the indoor average temperature and indoor temperature fluctuation as the objects,the multi-factor orthogonal test method was used to analyze the factor optimal level and significance level,and obtain the optimal combination and the significant level of each factor's impact on the objects.The heating system using solar energy as the heat source which cannot guarantee continuous and stable heating should set auxiliary heat source.In this paper,a casing phase change energy storage floor heating system based on solar energy and valley price electricity was established.A comprehensive evaluation index CEI,which considers both energy conservation and economy was proposed.The tube pitch,phase change material layer thickness,solar collector area and valley price electric heating time of the heating system were optimized by the hybrid generalized pattern search algorithm with particle swarm optimization algorithm in the Trnopt optimization tool.Through case analysis,the optimized system annual cost reduction rate is 58%compared with the primary system,and the operating cost reduction rate is 38%.The economic analysis results show that the optimized system operating cost reduction rate is 60%compared with the electric boiler system,operating cost reduction rate is 28.2%compared with the solar energy combined with auxiliary electric boiler system,and operating cost reduction rate is 13.1%compared with the valley electric energy storage system.The energy-saving analysis results show that the energy saving rate is 31.8%compared with the valley electric energy storage system and the energy saving rate is31.6%compared with the electric boiler system.The environmental benefit results show that the annual carbon emission reduction per unit area compared with the valley electricity storage system is 22.78 kgCO₂/m²,and the annual carbon emission reduction per unit area with the electric boiler system is 22.59 kgCO₂/m².