| The climate in northwestern my country and the Qinghai-Tibet Plateau is harsh in winter,and the heating demand lasts for a long time.The existing heating measures in rural areas are backward,and the indoor thermal environment needs to be improved urgently.However,this area is rich in solar energy resources,with most low-rise buildings,which can obtain a higher guarantee rate of solar heating,and has the prerequisites for the development of solar heating.The solar hot air heating system is simple in structure and convenient to maintain.It is not prone to freezing and damage to the hot water heating system.It is suitable for popularization and application in Northwest my country and the Qinghai-Tibet Plateau.According to previous studies by scholars,local residents have a distinct day and night differentiated activity law,that is,the living room and bedroom are the main activity spaces,and the use time is concentrated in the day and night respectively.Based on this,this paper proposes a solar hot air asymmetric phase change internal wall heating terminal,through the direct heating of the living room during the day,the bedroom heat storage during the day,and the night heat release to meet the needs of residents for the day and night differentiated heat of adjacent rooms.Environmental demand,and then realize the efficient use of solar energy.This paper first conducts a theoretical analysis of the heat transfer process of the asymmetric phase change solar hot air heating inner wall,and proposes thermal performance evaluation indicators such as heating efficiency and heat loss rate;builds a solar hot air wall thermal performance experimental platform,and analyzes the change The influence of phase change on the heat storage and release performance of the ventilated wall under the conditions of wind temperature and variable wind speed;a numerical model of the heat transfer process of the solar hot air wall is established,and the ordinary wall,symmetrical phase transition and asymmetrical phase transition are analyzed and compared The heat transfer characteristics of the wall;and then the influence of asymmetrical phase change ventilation wall on the indoor thermal environment is analyzed.The main research conclusions are as follows:(1)Compared with non-phase-change ventilated interior walls,the surface temperature and heat flow density on both sides of the asymmetric phase-change ventilated walls are significantly different.For the asymmetric phase change ventilation wall heating system,the average temperature of the bedroom side wall during the heat storage process is 4.68 ℃ lower than the average temperature of the living room side,and the average heat flux is reduced by 43.15 W/㎡;the bedroom side wall surface during the heat release process The temperature is 2.24 ℃ higher than that of the side wall of the living room,the surface heat flux density is increased by 29.65 W/㎡,and the time for the wall surface temperature to stay above 20 ℃ is prolonged by 3.1 h.(2)Through numerical simulation,the influence of wall material,phase change material thickness,phase change temperature,ventilation pipe diameter,pipe spacing and other parameters on the heat transfer characteristics of the wall is analyzed.For asymmetrical phase change interior walls,when lightweight concrete materials are selected,the surface temperature and heat flux amplitude of the ventilated wall are significantly reduced,but compared with heavy concrete walls,the heating effect of lightweight walls is poor.Increasing the thickness of the phase change material can extend the heating time of the system and reduce the temperature fluctuation of the wall surface.When the thickness of the phase change material is 20 mm,the effective utilization rate of the phase change material will be reduced by 38.19%.The lower the melting point of the phase change material,the smaller the temperature fluctuation of the wall adjacent to the bedroom surface,and the longer the heating period.When the phase change temperature is 26℃,the average heat flux density on the side wall surface of the bedroom decreases by 62.54 W/㎡ during the heat storage process.,The average surface temperature is reduced by 4.45 ℃.During the heat release process,the temperature of the bedroom side wall surface can be kept above 18℃ for 14 h.(3)By analyzing the heating efficiency and heat loss rate of the asymmetric phase change heating interior wall,the results show that the phase change heat storage material improves the heating efficiency of the light wall more significantly,and its heating temperature meets the acceptable heating temperature range Time is longer.Reducing the thickness of the phase change material can increase the heating efficiency and heat loss rate of the wall at the same time.When the distance between the phase change material and the center of the wall is 50 mm,the heating efficiency and heat loss rate of the wall are the highest;the melting point of the phase change material is 26 The heating efficiency of the wall is higher at ℃,and the utilization rate of the phase change material is 0.83.(4)Compared with the indoor thermal environment of the non-phase-change ventilated interior wall heating system,the asymmetric phase-change interior wall heating system can reduce the fluctuation range of indoor temperature and extend the heating time of the system.In the heat storage stage,the living room temperature of the asymmetrical phase change ventilation wall heating system is higher than the bedroom temperature,and the maximum temperature difference is 10℃.In the heat release stage,the bedroom side indoor temperature is higher than the living room indoor temperature,and the maximum temperature difference is 4 ℃,Which shows that through the asymmetrical design of the phase change heat storage layer of the ventilated wall,the day and night differential heating can be realized.Based on the above research,the heat storage and release characteristics of solar hot air concrete ventilated walls,symmetrical phase change ventilated walls and asymmetric phase change ventilated walls are analyzed,revealing that the solar hot air asymmetric phase change ventilated interior wall heating system heats indoors The influence of the environment provides a theoretical basis for the promotion and application of solar hot air heating systems. |
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