Optimizing the thermal environment of greenhouse with multi-pipe earth-to-air heat exchanger system using the Taguchi method

Greenhouses rely on an appropriate environment to support vegetable growth, and multi -pipe earth -to -air heat exchangers (EAHEs) are commonly used to regulate the temperature. In greenhouses, the high humidity resulting from plant respiration and transpiration has a significant effect on the thermal performance of EAHEs. This study employs the Taguchi method to optimize the multi -pipe EAHE for greenhouse applications, and high humidity conditions were taken into account. A complete greenhouse model was established, and experiments were conducted in Shandong province with real-time monitoring data used to verify the thermal environment of the greenhouse. Multivariate analysis was performed on EAHE parameters to evaluate their integrated performance. The optimized design combination was then implemented in the greenhouse. The findings reveal that the inlet air temperature exerted the most substantial influence on the integrated performance of the EAHE system, contributing significantly with a percentage of 45.20%. The velocity of the inlet air and diameter of pipes followed with contributions of 21.98% and 18.39%, respectively. The optimized EAHE system significantly improved the greenhouse's thermal environment, with the air diffusion performance index (ADPI) increasing to 65% and 98.33% at noon and midnight, respectively, making it more suitable for tomato growth. This study provides guidelines for selecting EAHE parameters in greenhouse applications, paving the way for the widespread use of EAHE systems in greenhouses.