University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 36 1 2026 04 20 Evaluation the effect of soil moisture on the performance and the efficiency of an open or closed loop geothermal system in a sample greenhouse Evaluation the effect of soil moisture on the performance and the efficiency of an open or closed loop geothermal system in a sample greenhouse 169 181 21388 10.22034/saps.2024.61526.3217 FA Abolfazl Hedayatipour Department of Biosystems Engineering, Shahid Chamran University of Ahvaz Mohsen Soleymani Department of Biosystems Engineering, Shahid Chamran University of Ahvaz Mostafa Kiani Deh-Kiani Department of Biosystems Engineering, Shahid Chamran University of Ahvaz Journal Article 2024 05 05 Background & Objectives: One of the accessible renewable energy sources in all parts of the world is surface geothermal energy. The objective of this experiment was evaluation the effect of the type of air circulation and soil moisture around the air transmission pipe on the output air temperature, efficiency and coefficient of performance (COP) of a shallow geothermal system in the cooling of greenhouse. Materials and Methods: A split plot experiment in the form of randomized complete blocks was conducted in a experimental greenhouses located in Arak region in four replications, from July to August 2022. The main plots were the soil moisture contents around the air transmission pipe at two levels of 25% and 10%, and sub plots were two types of air circulation, including open loop and closed loop. A centrifugal fan with a power of 760 watts was used for air circulation. Air circulation was open one day and closed the next. Using a single-channel data logger, the ambient temperature and air temperature entering and exiting the system were recorded and stored at 10-minute intervals. Efficiency and coefficient of performance were calculated during the hottest hours of the day. Finally, analysis of variance of the effect of experimental factors on dependent factors, and comparison of means were performed using MSTAT-C software. Results: According to the results, the effect of soil moisture content on the variables of system outlet air temperature, COP and efficiency was significant. Also, although the effect of the air circulation method (closed or open circuit) on the outlet air temperature was not significant, it significantly affected the coefficient of performance and efficiency. The interaction effect of these two independent variables was not significant on any of the dependent variables. The temperature of the fan inlet air (ambient air) during hot hours of the day had no effect on the fan outlet air temperature. Therefore, the use of the system is recommended both in temperate regions (central regions of the country) and in very hot regions (southern regions of the country). In the closed-loop method, with an increase in the difference between the inlet and outlet air temperatures of the system, the amount of power produced and the coefficient of performance of the system are greater compared to the open-loop method. Conclusion: The higher the ambient air temperature, the higher the COP and efficiency of the system. As soil moisture around the air transmission pipe increases, the output temperature of the system decreases. Therefore, the efficiency and COP of the system increases. Background & Objectives: One of the accessible renewable energy sources in all parts of the world is surface geothermal energy. The objective of this experiment was evaluation the effect of the type of air circulation and soil moisture around the air transmission pipe on the output air temperature, efficiency and coefficient of performance (COP) of a shallow geothermal system in the cooling of greenhouse. Materials and Methods: A split plot experiment in the form of randomized complete blocks was conducted in a experimental greenhouses located in Arak region in four replications, from July to August 2022. The main plots were the soil moisture contents around the air transmission pipe at two levels of 25% and 10%, and sub plots were two types of air circulation, including open loop and closed loop. A centrifugal fan with a power of 760 watts was used for air circulation. Air circulation was open one day and closed the next. Using a single-channel data logger, the ambient temperature and air temperature entering and exiting the system were recorded and stored at 10-minute intervals. Efficiency and coefficient of performance were calculated during the hottest hours of the day. Finally, analysis of variance of the effect of experimental factors on dependent factors, and comparison of means were performed using MSTAT-C software. Results: According to the results, the effect of soil moisture content on the variables of system outlet air temperature, COP and efficiency was significant. Also, although the effect of the air circulation method (closed or open circuit) on the outlet air temperature was not significant, it significantly affected the coefficient of performance and efficiency. The interaction effect of these two independent variables was not significant on any of the dependent variables. The temperature of the fan inlet air (ambient air) during hot hours of the day had no effect on the fan outlet air temperature. Therefore, the use of the system is recommended both in temperate regions (central regions of the country) and in very hot regions (southern regions of the country). In the closed-loop method, with an increase in the difference between the inlet and outlet air temperatures of the system, the amount of power produced and the coefficient of performance of the system are greater compared to the open-loop method. Conclusion: The higher the ambient air temperature, the higher the COP and efficiency of the system. As soil moisture around the air transmission pipe increases, the output temperature of the system decreases. Therefore, the efficiency and COP of the system increases.

https://sustainagriculture.tabrizu.ac.ir/article_21388_e0e83abada308894bd34ea8abe6aa58e.pdf