Study On The Effects Of Walls On Temperature Field And Heat Flux Of Greenhouse

The north wall of greenhouse is a kind of maintenance structure with function of the heat storage and release, which occupies an important position compared with other building envelope. In this paper, the experiment and simulation analysis are conducted aimed at three greenhouses with different structure of the north wall in the north cold-arid areas, and explore the difference between the composite wall and ordinary wall on heat preservation.Temperature test data shows:the hourly average temperature is the highest in the greenhouse with75cm ashes layer, the second one is in the back to back greenhouse, and the lowest one is in the greenhouse with3cm of polystyrene. The commons of three greenhouses:due to the heat storage of wall and ground during the day, the farther the distance away from the wall and the ground is, the higher the temperature is; it is opposite at night. The differences of them:during the day, the average temperature in the greenhouse with75cm ashes layer is the lowest, the second one is in the greenhouse with3cm polystyrene, and the highest one is in the back to back greenhouse; but average temperature in the greenhouse with75cm ashes layer is the highest, the second one is back to back greenhouse, the lowest one is in the greenhouse with3cm of polystyrene at night.The heat flux test data shows the following results. The commons of three greenhouses:the heat flux near by the middle position of wall surface is the highest of five test sensors. Greenhouse wall has the obvious function of the heat storage during day and heat release at night. The average heat storage time is from9:00to14:30, the average heat release time is from14:30to the next9:00. In sunny days, the heat storage and release function of three walls are more obvious than in the cloudy days. The differences of them:the heat storage and release functions of the greenhouse with75cm ashes layer are most obvious, whether sunny or cloudy. The heat released by three greenhouse walls can make their temperature improve3.8℃,2.3℃and6.3℃(Room temperature is below15℃).Finally, it shows that the simulation results are approximate with the test results by using the Fluent software, which illustrated the reliability and applicability of Fluent software.