Enhancing cooling tower efficiency using ammonium persulfate (APS) as a thermal performance additive

• APS introduced as a novel additive to enhance cooling tower performance. • Cooling range increased by up to 25 % and approach temperature lowered by 3 °C. • Optimal APS concentration (0.5–1.0 mol/L) boosts efficiency by 17.6 %. • APS enhances evaporation via reduced surface tension and endothermic action. • Model and experiments confirm APS as a scalable, cost-effective cooling enhancer. This study examines the influence of Ammonium Persulfate (APS) solutions at varying concentrations (0.1, 0.5, 1, and 2 mol/L) on the thermal performance of counterflow cooling towers. It focuses on their effects on outlet water temperature, air heat gain, humidity variation along the tower height, and overall thermal range. Experimental findings demonstrate that the APS solution markedly enhances cooling performance by expanding the cooling range by up to 25 %, lowering the approach temperature by as much as 3C, and boosting thermal efficiency. APS shows superior performance under higher inlet water temperatures and variable environmental conditions. At a concentration of 1 mol/L, particularly within the temperature range of 50–45C, the efficiency increases by 17.6 %, rising from 72.81 % to 85.69 %. The enhancement in heat transfer is attributed to three synergistic mechanisms: increased evaporation due to reduced surface tension, enhanced latent heat absorption through mild endothermic decomposition, and the strong agreement between a physics-based heat and mass transfer model and the experimental data. These results confirm the viability of APS as an efficient, practical, and scalable additive for optimizing cooling tower performance across a wide range of operating conditions.