Dynamic Simulation And Performance Study Of Phase Change Energy Storage Wall With Thermoelectric Conversion Technology

Building envelope has an important impact on building cooling and heating load and energy consumption level.Passive building envelope based on phase change energy storage technology has the characteristics of large heat capacity and strong heat storage capacity and can effectively reduce the impact of outdoor disturbance on indoor environment.But there are also some problems such as low thermal conductivity and slow heat absorption and release efficiency.The active building envelope with thermoelectric refrigeration（heating）technology has the advantages of rapid response and active control of heat flow.But there are also some problems such as large temperature difference between hot and cold end and low refrigeration efficiency.In this paper,phase change energy storage technology and thermoelectric refrigeration technology are combined to build a new wall system.The wall system not only has the characteristics of large heat capacity,strong heat storage capacity and active control of heat flow,but also can effectively improve the heat absorption and release efficiency of phase change materials,r educe the temperature difference between hot and cold end of thermoelectric module,and improve the refrigeration efficiency of thermoelectric module.It is an ideal new energy-saving building envelope.The envelope can make full use of the natural cold so urce at night in summer and the solar radiation in daytime in winter,and realize the functions of heat insulation and refrigeration in daytime in summer and heat insulation and heating in daytime in winter,which is of great significance to promote buildi ng energy conservation and reduce building carbon emissions.Firstly,this paper introduces the structure and working principle of the wall system.Secondly,the dynamic mathematical model of the wall system is established.Under the condition of typical meteorological parameters,this paper simulates and optimizes the performance of the wall system in hot summer and cold winter area in summer and winter,and analyzes the influence of current,thermoelectric arm length,phase change material thickness,phas e change latent heat and phase change temperature on the performance of the wall system.Finally,the model is used to simulate and analyze the performance of the wall system in summer and winter of typical cities in different climate regions.The relationship between the performance of the wall system in hot summer and cold winter areas and the influencing factors is as follows:（1）In summer,the wall system should be mainly heat insulation and supplemented by refrigeration.And the working current applied to the wall should be determined according to the surface temperature of the wall slightly lower than the indoor air temperature.In winter,heat preservation and heating should be considered at the same time.And the working current applied to the wall should be determined according to the average temperature of the phase change material slightly higher than the outdoor air temperature.（2）The performance of the wall system is positively correlated with the thermoelectric arm length.（3）The thickness of PCM should be determined according to the performance in summer.And the current should be adjusted to make full use of different thickness of PCM to absorb solar radiation heat in winter.（4）The latent heat of PCM has nothing to do with the maximum performance of the wall system,but has something to do with the duration of the wall.（5）The phase transition temperature of PCM should be 2-4℃higher than the average temperature in summer.The simulation results of the performance of the wall system in different climate regions show that:（1）In severe and cold regions,the cooling capacity of the wall system is between 25-30Wm^-2,and the cooling efficiency is between 0.7-0.8.The heating capacity is 35-50 Wm^-2,and the heating efficiency is between 1.2-1.6.In hot summer and cold winter areas,the cooling capacity of the wall system is about 10Wm^-2,and the cooling efficiency is about 0.3.The heating capacity is about 40 Wm^-2and the heating efficiency is about 1.2.In hot summer and warm winter areas,the cooling capacity of the wall system is about 5 Wm^-2,and the cooling efficiency is about 0.2.The heating capacity is about 35 Wm^-2 and the heating efficiency is about4.3.In mild areas,the heating capacity of the wall system is about 61 Wm^-2,and the heating efficiency is about 1.8.（2）In severe cold area and cold area,the performance of the wall system is relatively balanced.In ho t summer and cold winter areas and hot summer and warm winter areas,the performance is relatively poor in summer and better in winter.（3）The wall system can achieve the functions of heat insulation and cooling in summer and heat insulation and heating i n winter in different climate regions.In summer,the cooling performance of the wall is better in the area with large temperature difference between day and night.In winter,the heating performance of the wall is better in the area with larger solar radi ation.The wall system is an energy-saving building envelope and it has the functions of heat insulation and cooling in summer and heat insulation and heating in winter,which can make full use of the natural cold source at night in summer and the solar radiation in daytime in winter.The wall system provides a reference for the design and optimization of new building envelope.