Abstract
Decreasing the temperature of a greenhouse in summer is very important for the growth of plants. To investigate the effects of a roof sprinkler on the heat environment of a greenhouse, a three-dimensional symmetrical model was built, in which a k-ε (k-epsilon) turbulent model, a DO (Discrete Ordinates) irrational model, a Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm, and a multiphase model were used to simulate the effects of the roof sprinkler, at different flow rates. Based on the simulation results, it was found that the temperature could be further reduced under a proper sprinkle rate, and the temperature distribution in the film on the roof was more uniform. A test was conducted to verify the accuracy of the model, which proved the validity of the numerical results. The simulation results of this study will be helpful for controlling and optimizing the heat environment of a greenhouse.
Highlights
In summer, the air temperature in a greenhouse can exceed 40 ◦ C, which has implications for the growth of crops [1] and increases the cooling-energy consumption
This study investigated the effects of the roof sprinkle process on a greenhouse, in summer, by using numerical methods, combined with a solar radiation and porous media model, to explore the effects of different roof sprinkler flow rates on greenhouse cooling
The temperature decrease range was 10−12 ◦ C, which was better than the result from He et al (2018), who found that sprinkling water reduced the roof temperature 2−7 ◦ C
Summary
The air temperature in a greenhouse can exceed 40 ◦ C, which has implications for the growth of crops [1] and increases the cooling-energy consumption. Roof sprinkling is one of the most effective ways to reduce the temperature of a building It works by sprinkling water on the roof and utilizing the process of evaporation to cool it [5,6,7]. He et al [5] adopted the method of sprinkling water on the external surfaces of greenhouses, which were coated with a super-hydrophilic photocatalyst (TiO2 ). The cooling effects of a passive roof cooling method, i.e., a roof with a water jacket, a water pond, and a radiation shield, respectively, were investigated by Sabzi et al [6]. Zhao et al [7] found that in a roof that is exposed to the solar radiation condition, the maximum temperature of the outer roof could reach 57.8 ◦ C, while the maximum temperature of the outer roof was about 37.2 ◦ C with a roof spraying water system
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