| The central heating mode of a thermal power plant requires the laying of heating pipes,which is costly and difficult to radiate to remote rural areas far away from thermal power plants.Therefore,rural residents can only rely on small coal fired boilers for heating in winter,which increases environmental pollution and energy waste.On the other hand,some industrial processes other than electric power production,such as metal smelting,wine making,etc.,would generate a large amount of industrial waste heat and waste heat,and the general temperature can reach above 200 °C.It is the focus of this paper that how to storage industrial waste heat and waste heat to alleviate the waste of resources,environmental heat pollution and the lack of heating in some areas.In order to realize the long-term storage and space transfer of waste heat,this paper designs a phase change heat storage device composed of energy storage plates,which takes advantage of the amount of thermal energy transfer in the process of storage/discharge using phase change materials.Considering the factors such as industrial waste heat temperature,device heat storage,phase change material thermal conductivity and economy,70# phase change material produced by Shanghai Huangming Solar Energy Co.,Ltd.is selected as the energy storage medium.The phase change material loaded in the energy storage plate absorbs or releases a large amount of latent heat when a phase change occurs,thereby realizing the storage/discharge function of the energy storage device.The first part of the paper is to design the physical model of the latent heat storage device.In case of considering natural convection,the numerical simulation of the storage/discharge process of Fluent is carried out,and the temperature field,solid-liquid interface and liquid phase curve of the phase change material at different times are obtained.The simulation results show that natural convection occurs under the action of the lift force and the temperature difference,and the heat transfer is enhanced as the liquid phase ratio of the phase change mat erial increases during the heat storage process.It lasts about 5 h of heat storage.After solidification,the phase change material settles to the lower wall surface of the energy storage plate by gravity,which hinders the heat exchange between the heat exchange fluid and the phase change material,and seriously reduces the heat release efficiency.The exothermic process lasts about 6.5 h.Subsequently,this paper proposes a method of adding fins to enhance heat transfer,which breaks through the technical “bottleneck” of slow heat storage and poor heat release performance of traditional heat storage devices,improves the heat storage rate,and optimizes the heat release effect.This paper also discusses the influence of fin mounting position and fin geometry such as spacing,height and thickness on the heat transfer effect of phase change materials.The results show that the effect of strengthening the heat transfer on the side of the phase change material is more obvious.At the same time,the most obvious fin spacing is 40 mm,the fin height is 40 mm,and the fin thickness is 8 mm.Finally,based on the model of the energy storage device optimized by the simulation results,a mobile energy storage and heating system is designed to heat the winter heating of a residential building.On this basis,the heating capacity and equipment cost of the mobile heat source are calculated,and the feasibility and economy of the heating system are analyzed.By replacing the coal-fired boiler,the calculation shows that the operating cost of each heating season of the heating system is 240,000 yuan to 320,000.By this way,360 tons of coal can be saved,and the cost per ton of coal saved is 660~880 yuan.This is a win-win situation for both economic and social benefits. |
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