Performance Evaluation of Volcanic Stone Pad Used in Evaporative Cooling System

Abstract

The evaporative cooling system (ECS) is an energy-efficient and eco-friendly air-cooling technology that is very effective in dry climates, and the conventional method with cellulosic pads is widely used. However, because of the accumulation of dust and salts, these pads have a tendency to degrade quickly. This study aimed to examine the viability of using volcanic stone (Scoria) as an innovative material for evaporative cooling pads. The experiments were conducted in a wind tunnel (0.4 m × 0.6 m) with different pad thicknesses (d = 10 cm and 15 cm), water addition rates (mw =1.6, 2.4, and 4 kg.min−1.m−1), and air speeds (v = 0.75, 1.25, and 1.75 m·s−1). The results showed that the 10 cm thick pad consistently performed better than the 15 cm thick pad across all air speeds and water addition rates. The 10 cm thick pad achieved the highest cooling efficiency of 82% at a water addition rate of 2.4 L.min−1.m−1 and an air speed of 1.75 m·s−1. In contrast, the cooling efficiency for the 15cm-t hick pad was 64% under the same conditions. The 10 cm thick pad consumed more water (1.8 to 2.8 kg·h−1 compared to 1.0 and 2.4 kg·h−1 for the 15 cm pad), as the ECS performance was directly associated with the amount of water used. Higher air speed led to a drop in pressure, which impacted fan performance. The pressure drops across the pads were between 10 and 13 Pa for an air speed of 1.75 m·s−1. These results suggest that volcanic stone (Scoria) pads can provide effective cooling performance similar to that of commercial cellulosic pads but have added benefits of durability, less maintenance, and biological degradation resistance. The non-evaporative medium, especially the 10 cm thick Scoria pad, could be a more viable medium for evaporative cooling applications in arid areas.