| The solar greenhouse is an important infrastructure building for the growth of counterseason vegetables.Due to the instability and intermittentity of solar energy,as well as the cold winter in Northwest China,the passive thermal environment construction technology of solar greenhouse is constantly challenged.In this paper,the method of theoretical analysis,experimental verification and numerical combination is used to carry out exploratory research focusing on the construction method of active and passive phase change greenhouse north wall.Under the premise of meeting the thermal environment in greenhouse and improving the thermal performance and land utilization ratio of walls,the thermal design principles and methods of active and passive phase change greenhouse walls are studied as follows:(1)By setting up the thermal performance test bench of the wall of the active and passive phase change greenhouse and building the heat transfer model of the 1:1 active and passive solar greenhouse,and comparing the measured data such as the surface temperature of the wall,the air temperature in the greenhouse and the average temperature of the phase change material,the results show that the numerical results of the heat transfer model are in good agreement with the test results,and the average error is less than 10.2%.(2)The heat transfer model of active and passive phase change greenhouse is used to optimize the thickness of insulation layer,phase change heat storage layer and bearing brick wall layer in the wall structure of active and passive phase change greenhouse.The research shows that under typical weather conditions in Lanzhou,the XPS insulation layer of active and passive phase change greenhouse in Lanzhou is 80 mm,the phase change material thickness is 160 mm and the bearing brick wall thickness is 490 mm.That is,120 mm brick wall + 160 mm phase change material layer + 490 mm bearing brick wall + 80 mm XPS insulation layer is the preferred structural thickness of active and passive phase change greenhouse wall in Lanzhou area.(3)A better active and passive phase change greenhouse wall structure in Lanzhou is obtained.By comparing various parameters under typical sunny conditions,it is found that the heat storage of active and passive phase change wall structure is 17.7%,22.1% higher than that of common wall structure,and the overall heat storage and release efficiency is increased by about 3%.In this paper,a heat transfer model is built for the active and passive phase change greenhouse,and the wall structure is optimized by the model.A method for building the active and passive solar greenhouse wall is proposed.It plays a certain reference role for the construction of active and passive phase change solar greenhouse wall in Lanzhou area.It provides relevant reference for wall structure optimization of active and passive phase change greenhouse in the future. |
