Numerical Study Of Heat Transfer Performance Of Phase Transition Trumbo Walls

With the development of science and technology,people’s quality of life is improving.People have many more requirements for the comfort of the building environment,which lead to the growth of building energy consumption,especially the consumption of fossil energy.The passive application of solar energy in Trombe-wall building can effectively reduce building energy consumption and environmental pollution caused by fossil energy.However,the traditional Trombe-wall is greatly affected by the periodic change of solar radiation,and it is easy to reach a high temperature during the day and a low temperature at night.In order to enhance the adaptability of the traditional Trombe-wall,phase change materials can be added into the traditional Trombe-wall to store much more thermal energy through the phase change process.As a result,the influence of the periodic change of solar radiation and the fluctuation of indoor temperature can be reduced effectively.In the western region of China,the Trombe-wall has been widely used due to the high intensity of solar radiation.In Eastern China,the application of phase change Trombe-wall is relatively less because the solar radiation intensity is lower than that in Western China.This paper focuses on the heat transfer and storage characteristics of phase change Trombe-wall in winter cold climate in Eastern China.Firstly,taking Jinan area as an example,the enthalpy method mathematical model of phase change Trombe-wall system is established by combining theoretical analysis with numerical simulation,the general structure and working principle of Trombe-wall are described,and the heat transfer process from outside to inside is analyzed according to the different materials of each layer of the enclosure.Secondly,the mathematical model of turbulent flow and heat transfer inside the wall is established by enthalpy method.COMSOL software,based on finite element method is used to solve the equations,and the validity of the mathematical model is verified.The thermal performance of phase change Trombe-wall in Jinan area is analyzed in the follow part.In order to obtain the characteristics of heat transfer and storage the Trombe-wall under the actual meteorological conditions,and determine the advantages of phase change Trobe-wall in building energy saving in Jinan area,the outdoor temperature and solar radiation wall in Jinan area obtained through experimental test,are brought into the mathematical model as the input condition.The changes of the parameters of the enclosure and the phase change materials play important roles in the performance optimization of the phase change Trombe-wall.The function of heat transfer and heat storage of the phase change wall are affected by the thickness of the air passage,the air supply volume,the thickness of the phase change material layer and the utilization rate of solar energy.The results show that the thermal properties are better when the thickness of windway is 100 mm than other cases.The air supply volume affects the air flow uniformity in the duct,and then affects the convective heat transfer between the air and the surrounding media,as well as the air temperature uniformity in the windway.The performance of Trombe-wall will be best among the presented cases while the emissivity and absorptivity of PCM are 0.1 and 0.9 respectively,and the thickness of PCM(phase change material)layer is 15 mm.In this paper,the relevant optimization parameters of phase change wall under Jinan Meteorological conditions are given,which can provide a theoretical reference for the application of phase change wall in winter cold areas with suitable solar radiation intensity.