Performance evaluation of root zone heating system developed with sustainable materials for application in low temperatures

Abstract

The proposed system was developed to help the farmers of the Yangtze River Delta to grow greenhouse plants over winter, as the region has very low winter temperatures. For this reason, the experiment was undertaken during winter in extremely low temperatures to obtain optimal results. Keeping in mind the importance of sustainable practices, the authors developed the system using sustainable materials. The system was heated for 6 hours and then the hourly heat transfer rates were measured for 12 hours. The power consumption data of the heating system during different ambient temperatures were collected. Additionally, a simulation model of the heating system was developed using the COMSOL Multiphysics 5.3a package. The heat transfer in a porous media model was used in this study. Finally, the simulation results obtained from the COMSOL Multiphysics 5.3a package were analyzed and compared to the experimental results; these results were found to be in good agreement, thus authenticating the simulation model. After analyzing the data obtained from both methods, the power consumption of the heating system during different ambient temperature conditions were also calculated, which ranged from 15.73 W to 70.02 W in the simulated method and 28.2 W to 91.2 W in the experimental method. It was found that the root zone temperature remained in the range of 0-35 °C. This range of root zone temperature is suitable for many greenhouse horticultural crops such as tomato, cucumber, pepper, strawberry, lettuce, etc. The optimal root zone temperatures of many greenhouse horticultural plants are verified by many researchers.