Research On Performance Of Phase Change Heat Storage Heating Device Based On Spherical Package

With the continuous development of China's economy,there has been a serious shortage of conventional energy to support growth.And the proportion of building energy consumption to national energy consumption reached 33%.Under this trend,the development of new energy sources has become inevitable.With the rapid development of heat utilization such as solar energy and air energy,in order to reduce the disadvantages of low energy density and poor continuity,heat storage technology has become particularly important.The heat storage technology has three types:latent heat,sensible heat and chemical reaction energy storage.Among them,phase change heat storage has attracted more extensive attention and research due to its large latent heat,high thermal efficiency,good stability and easy control.In this work,a phase change heat storage heating device based on spherical package is designed and its thermal performance is studied.The main work includes:Firstly,under the heating index,the heat load required for the 15m² ordinary housing is calculated and determined,and then the heat storage capacity of the phase change heat storage device is determined.Secondly,the thermal properties test of the PCM with Ba?OH?₈ as the main material was carried out to obtain the thermal property parameters.Then,according to the heat storage of the phase change heat storage heating device and the thermal property parameters of the PCM,the amount of PCM is calculated,and the structural form of the spherical package is determined.The phase change heat transfer theory is discussed and analyzed and related mathematical models are established.Finally,using Fluent's pre-processing software ICEM CFD for modeling and meshing,then importing Fluent and performing computational simulation.In order to study the performance of the phase change heat storage device,the performance analysis of the water tank containing three kinds of heat storage balls of different diameters of50mm,65mm and 80mm was firstly analyzed,and the phase change water storage tanks of the three different energy storage balls were obtained.The heat storage time is 2220s,2750s and3540s.The device with 50mm and 65mm diameter energy storage balls is shortened by 1320s and 790s respectively compared with the device with 80mm diameter energy storage ball.The heat storage efficiency is increased by about 37%and 22%respectively..The overall heat release time was 26620s,29370s and 31480s,and the exothermic time was shortened by 4860s and 2750s,respectively,and the exothermic efficiency was increased by about 15%and 9%,respectively.That is to say,in the actual heating,a reasonable choice of the diameter of the energy storage ball can effectively improve the heat storage efficiency;after that,the phase transition process of the heat storage ball inside and the whole heat storage ball is analyzed,and the phase change law and heat transfer mode are obtained.Finally,the simulation and analysis of the storage and release heat of the device are carried out for a number of different operating conditions.The heat transfer rates of the three different flow conditions are only slightly different.The change of different flow rates has little effect on the phase change process of PCM.The maximum difference in phase change overall time during heat storage is only 1.7%,and only 2.3%when exothermic.