EFFECT OF WATER FLOW RATE AND AIR VELOCITY ON THE PERFORMANCE OF EVAPORATIVE COOLING SYSTEM FOR GREENHOUSE

Climate change has become one of the most critical challenges affecting agricultural production worldwide. Environmental control inside greenhouses provides an effective strategy to mitigate the adverse impacts of such climatic variations. The primary objective of this study was to optimize the operational parameters of an evaporative cooling system, namely water flow rate and air velocity. To achieve this, experiments were conducted under three different water flow rates (2, 4, and 6 L·min⁻¹·m⁻²) and three air velocities (1.0, 1.25, and 1.5 m·s⁻¹), with and without shading nets. The effects of these parameters on greenhouse air temperature, relative humidity, cooling efficiency, and cooling capacity were evaluated. The findings revealed a clear correlation between indoor and outdoor air temperatures, where the indoor temperature followed the outdoor trend, increasing during the early morning, peaking at noon, and then declining as solar radiation decreased. Similarly, the relative humidity of the outdoor air increased during nighttime and decreased during daytime in response to the temperature rise. The results demonstrated that the maximum cooling efficiency (94.36%) was achieved at an air velocity of 1.25 m·s⁻¹ and a water flow rate of 4 L·min⁻¹·m⁻² in the presence of shading nets. In contrast, the highest cooling capacity (91.96 kW) was obtained at an air velocity of 1.5 m·s⁻¹ with the same water flow rate under shaded conditions. In general, the most efficient performance is achieved by operating the evaporative cooling system with shading nets at a water flow rate of 4 L·min⁻¹·m⁻² and an air velocity of 1.25 m·s⁻¹. This combination not only maximizes cooling efficiency but also contributes to achieving a more stable greenhouse microclimate.