Prototype development of a fogging evaporative cooler for indoor thermal comfort in the CPU Engineering student council office

Abstract

This research tackles the growing issue of indoor thermal discomfort in tropical regions by designing, assembling, and evaluating a fogging evaporative cooler prototype for the Engineering Student Council Office at Central Philippine University in Iloilo City. Due to increasing global temperatures and elevated humidity in the Philippines, traditional air conditioning systems consume a significant amount of energy and are expensive. The evaporative cooler with fogging features a 50-liter water reservoir, a 12-head ultrasonic mist generator (8.4 kg/hr fog production), a chassis fan, and a stand fan, designed as an energy-saving option. The cooling load for the office was determined to be 4405.18 W (5.91 HP) utilizing psychrometric analysis and evaluations of thermal load.

Testing in both open (ventilated) and closed (sealed) setups during 8-hour operation periods showed temperature decreases of 0.6–1.1°C (for open) and 1.2–3.0°C (for closed) when compared to outdoor maximums of 31.1°C. While the desired conditions of 24°C and 50% relative humidity (RH) were not met, indoor temperatures settled between 27–30.9°C. Humidity increased to 68–73% RH (open) and 84–90% RH (closed), underscoring the essential role of ventilation in managing moisture. The system used 0.8 L/h of water (6.4 L overall) and functioned at ₱67.80/day (0.565 kW total power).

Despite its affordability and low energy consumption, the research does not recommend the prototype for practical application. Rather, it serves as an exploratory study that reveals the performance limitations of fog-based evaporative cooling in humid indoor conditions. The study provides a foundation for further investigation and refinement of low-cost cooling technologies suitable for tropical climates.