Parametric Analysis of Cold Surface Temperature for Enhanced Thermal Regulation and Moisture Recovery in Greenhouses

Greenhouses in arid and semi-arid regions simultaneously face two major challenges: severe water scarcity and excess humidity, the latter causing condensation on the inner surfaces and the dripping of droplets onto crops, which encourages fungal diseases and physiological stress. Existing studies typically address these issues separately and often rely on energy-intensive cooling or dehumidification systems. In this work, we propose a fully passive and autonomous condensation-based strategy that combines a geometrically optimized roof inclination with a naturally cooled surface supplied by a Canadian well. The 7° inclination is selected based on a prior comparative study demonstrating its ability to channel buoyancy-driven humid air toward the roof apex of the greenhouse, where condensation can be maximized. A 3-D transient CFD (Computational Fluid Dynamics) model coupling airflow, heat transfer, radiation, and vapor transport is used to evaluate the impact of three cooling temperatures (20, 16, and 12°C) on the internal thermo-hygrometric dynamics. Results show that lowering the cooling temperature intensifies upward convection, enhances moisture accumulation at the roof apex, and significantly increases the condensation potential. The 12°C configuration produced the strongest airflow acceleration and the highest vapor recovery efficiency, aligning with the natural cooling potential provided by a Canadian well. This parametric analysis establishes the optimal operating temperature for future integration of a passive condensation–recovery system aimed at improving both microclimate regulation and freshwater generation in arid-climate greenhouses.