An Estimation Method for Greenhouse Temperature Under the Influence of Evaporative Cooling System

Abstract

Temperature is one of the most important plant growth parameters that should be controlled in the greenhouses. The present study was aimed to assess the thermal behavior of a greenhouse with and without the fan and pad (FP) evaporative cooling system. A method was developed to approximate the greenhouse temperature based on the mass and energy balance equations. For this purpose, both of the fan and pad evaporative cooling system, and the greenhouse were studied. The results of the theoretical analysis were compared with those achieved by the experiments. Maximum deviations of 5.32, 5.56 and 4.53oC were observed between the theoretical and experimental temperatures of the inside air, the floor and the cover of the greenhouse without the cooling system, respectively. Whereas, the mean absolute error values associated with the predicted temperatures of the greenhouse with the FP system were ranged between 1.50 and 25.67%. Based on the obtained values for the correlation coefficient, root mean square error and mean absolute magnitude error, it was concluded that the models satisfactorily predicted the temperature of the greenhouse components. An air circulation system inside the greenhouse can be proposed to maintain the lumped condition even at the high temperatures, and lead to smaller errors. The results indicated that the inside air, the floor and the cover temperature of the greenhouse reduced by respectively 20.6, 13.0 and 20.6 o C when using the FP system with the air velocity of 4.4 ms -1 and the pad thickness of 6 cm.

Software for Sizing Pad-Fan Evaporative Cooling Systems of Greenhouses

“…This procedure is a constant need for professionals in the agricultural sector, especially those who work with greenhouses (NELSON, 1991;MISRA;GHOSH, 2018). Currently, this sizing is performed manually or through spreadsheets and tables, spending time as it requires caution when considering the values and equations applied (SHOJAEI et al, 2021). Thus, a software capable of performing these calculations and speeding up this procedure is required, helping the professionals of the agrarian sciences in their analyses and acting as a didactic tool.…”