Artistic Expression And Performance Analysis Of Building Envelope Integrated With Solar Thermal System

The appearance of solar collectors is generally black or dark blue,which is difficult to integrate with some architectural styles.At present,there are few studies on the appearance modification of solar collectors,and some modification methods lead to the serious decline of thermal collecting performance.Therefore,it is necessary to explore a method to enrich the appearance of solar collectors,so that the solar collectors can be integrated with a variety of architectural styles on the premise of maintaining a high thermal collecting performance.Due to its flat shape and simple structure,the flat-plate solar collector is easy to be integrated with buildings.This paper proposes to change the appearance of flat-plate solar collector by color coating on the cover plate,which provides a new idea for the development of building integrated with solar thermal system.There are three main research works in this paper.First,using halftone technique for reference,the "dot matrix" spraying process and the "mesh" coating process of photosensitive seals were tested,and the coating samples were tested for spectrophotometry and chroma.Secondly,the effect of coating on thermal collecting performance was investigated by comparing the flat-plate solar collectors with different types of cover plates.Thirdly,an experimental building based on northern folk houses was designed and constructed.The building envelopes including walls and roofs were integrated with the flat plate solar collectors,whose cover plates were coated by sprayed "dot matrix".The imitation effect of painting on the appearance of northern folk houses was evaluated by questionnaire survey and expert scoring.The thermal performance and energy saving effect in winter of water heater mode,thermal storage wall mode and night insulation mode of the building envelope integrated with solar thermal system were investigated.EnergyPlus was used to simulate the working conditions of the wall integrated with solar collector in summer.The main conclusions of this paper are as follows.1.Compared with the “dot matrix” coating,the “mesh” coating of photosensitive seal has higher transmittance and lower color chroma and lightness.Compared with continuous coating,half-tone coating has higher transmittance,lower chroma and lightness of color,and slight changes in tone.The above results show that the high transmittance of coating on the cover plate of flat-plate solar collector will cause low brightness and chroma.2.The reduction of thermal collecting performance caused by coating on the cover plate is less than the reduction of transmittance of the cover plate.Coating reduces the transmittance of the cover plate and increases the absorption rate,resulting in lower temperature of the heat absorber plate and higher temperature of the cover plate,which can reduce the heat loss of the heat absorber plate through the cover plate.Most of the heat absorbed by coating on the outer surface of the cover plate is directly lost,so coating on the inner surface of the cover plate is better than coating on the outer surface of the cover plate.3.The results of questionnaire survey and expert scoring show that the coating effect of the breast of the experimental building is the most recognized,followed by the coating effect of the roof,and the coating effect of the east and west walls is not recognized.Three performance strategies to imitate the effects of other exterior finishes with painting have been verified,namely,shape features are given priority,contrast between light and shade is given priority,and viewing distance and viewing angle are taken into account.4.The test results of the experimental building show that the water heater mode of the building envelope integrated with solar thermal system can provide sufficient domestic hot water for the average home.The thermal storage wall mode can greatly increase the temperature of the wall,and the heat stored in the wall can continue to provide indoor heating for 5 hours after the end of solar irradiation,reducing heating energy consumption.The night insulation mode can reduce the heat consumption of the wall and reduce the heating energy consumption by about 8%.The simulation results show that the building envelope integrated with solar thermal system has the problem of overheating in summer,which can be alleviated by internal sunshade combined with water heater mode.To sum up,the coating on the cover plate can enrich the appearance of the flatplate solar collector and make it easy to integrate with the building.Although the performance of the flat-plate solar collector is decreased due to the influence of coating,the integration of the flat-plate solar collector with the building improves the thermal insulation performance of the building envelope and achieves the energy-saving effect.