Experimental evaluation of residential evaporative air cooler performance using natural waste fiber pads as low-cost alternatives to commercial pads

This study explores a low-cost cooling option suited to hot and dry regions, where unstable electricity limits access to conventional air conditioning. Evaporative cooling is regarded as a viable strategy to minimize CO 2 emissions originating from electricity production. Many low-income households rely on evaporative cooling. In this investigation, three locally available waste materials; rice straw, date palm fibers, and Alhagi maurorum, were examined as alternatives to a commercial cellulose pad in a domestic evaporative cooler. An experimental setup was operated under real summer conditions. Twenty tests were conducted for each pad. Key variables included the outdoor air conditions and supply volumetric airflow rate. Cooling effect, capacity, saturation effectiveness, and energy efficiency ratio were evaluated. Readings were recorded after steady-state conditions were reached, which required about 10–15 minutes. After that, data were collected at regular intervals. The results show clear performance differences among the tested pads. Regarding cooling capacity, increases in outdoor air temperature or supply volumetric airflow rate resulted in higher capacity across all pads. The cellulose pad consistently delivered the best performance. It showed an average increment of 9.2%, 14.3%, and 19.2% when compared with rice straw, date palm fibers, and Alhagi maurorum, respectively. In terms of effectiveness, the cellulose pad ranked highest among all pad materials. It exceeded rice straw by 10.6%, date palm fibers by 20.14%, and Alhagi maurorum by 27.36%. A similar pattern was observed for the energy efficiency ratio. Overall, rice straw demonstrates promising behavior. It can be considered a practical substitute for commercial pads. Despite the superior thermal performance of the commercial cellulose pad, rice straw provided the best balance between cooling performance and overall cost owing to its remarkably low fabrication cost. In addition, the lower moisture transfer achieved by the agricultural residues contributed to reduces seasonal water consumption, further improving their economic feasibility for low-cost evaporative cooling applications.