| Solar energy is considered as an important way to solve energy problems because of its characteristics of sustainability,and environmental protection.However,the use of solar energy has the limitation of non-uniform time distribution.Solar thermal storage technology is to study this issue.In addition to energy issues,people nowadays have a higher demand for living environment.Under the background of increasing house prices,how to use limited living space is also a very important research direction.This paper combines these two problems and designs a fast wall-mounted natural circulation phase-change solar thermal storage device.The device can be suspended or inlaid on an outdoor wall or balcony.It does not need to have a height difference with the collector to complete the natural circulation,and can quickly get the hot water needed for life.For the research of wall-mounted natural cycle phase-change instantaneous water solar thermal storage device,this paper seeks a suitable thermal storage material for the requirements of this paper by consulting the literature.Then it proposes a feasible thermal storage device structure.Then it calculates the natural circulation resistance of the heat storage structure.Finally,the heat storage and heat release process was simulated by Flunet software,and the feasibility of the device was verified.The following methods and conclusions have been obtained:1.A new structure of a heat storage device is proposed,which is flat and can be suspended or inlaid on an outdoor wall balcony.Besides,this device can achieve natural circulation by utilizing the temperature difference between the solar collector and the thermal storage device.Directly connecting to the municipal pipe network,it can also achieve rapid heat release.Finally,the size of a phase change thermal storage tank for a four-person shower with hot water is determined.2.Combining the engineering calculation method for the natural circulation of the plate solar hot water system and the heating system,a calculation method suitable for the natural circulation resistance of the thermal storage device is obtained,which can be used to calculate the circulation resistance of the natural circulation thermal storage tank of this structure and similar structures.Besides,resistance calculations for this design condition have been conducted.3.Through the simulation and calculation of the heat storage process at the designed flow rate and other different flow rate in the vicinity of which,it was found that the heat storage process can be completed within the design time under the design flow rate and the nearby flow velocity.The circulation pressure is calculated according to different water temperature of the heat storage process at different flow rates,which is greater than the resistance loss of the heat storage device.Thus,the heat storage device can perform natural circulation.4.Based on the simulation and calculations of the snake tube exothermic structure with different pipe diameters in this design scheme,it is found that the heat transfer will weaken as the flow rate increases for the same diameter pipe.For the same flow,it is not always the best heat transfer effect for a given diameter.When the flow rate is from 100 to 200kg/h,the heat exchange of the larger pipe diameter is better.When the flow rate is higher than 200kg/h,the heat transfer effect of the smaller pipe diameter is better.5.The exothermic structure of cross pipe was simulated and it was found that the structure is more suitable for the design.The parameters such as pipe diameter,pipe length,and tube bundle number under this working condition were determined. |
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