TRNSYS-Based Performance Study of Solar-Assisted Single-Effect Absorption Cooling in Peshawar, Pakistan

Abstract

This study presents a detailed techno-economic and thermal performance evaluation of a solar-assisted absorption cooling system optimized for the climatic conditions of Peshawar, Pakistan. Through dynamic simulations conducted over the summer season (May to September), the performance of key subsystems, including the solar collector array, auxiliary heater, thermal storage, and absorption chiller, was analyzed. Simulation results demonstrate that the system successfully maintains the chilled water outlet temperature at 7°C, with consistent cooling water and hot water temperatures of 28°C and 95°C, respectively. The system exhibits steady-state flow rates of 650 kg/hr (cooling), confirming effective hydraulic control. Under variable load conditions, the auxiliary heater responded through frequent pulsed flow patterns, achieving peak flow rates up to 49,000 kg/hr without compromising outlet temperature. Parametric analysis revealed that the optimal tilt angle for solar collectors is approximately 15°, maximizing solar fraction (SF) for both flat plate collectors (FPC) and evacuated tube collectors (ETC). For ETCs, primary energy savings (PES) (fsav,shc) of 0.49 were achieved using 560 m² of collector area and 14.9 m³ of thermal storage. The ideal storage volume was found to be 25 L/m², beyond which auxiliary energy consumption increased. Seasonal simulations revealed strong diurnal variations in cooling demand, peaking around 1.6 MW, while heating loads remained negligible, reinforcing the cooling-dominated nature of the operational period. The system's average seasonal solar collector efficiency was calculated at 0.188 for FPCs and 0.52 for ETCs, underscoring the superior thermal performance of ETCs at higher driving temperatures (111°C). A minimum of 400 m² collector area was required to achieve 50% primary energy savings. These findings validate the hybrid solar-auxiliary configuration’s suitability for high-demand cooling applications in arid climates and offer design insights for optimizing collector area, storage volume, and control strategies. The results not only optimize system design for local climatic conditions but also underscore the broader potential of solar cooling technologies to mitigate urban heat, lower electricity demand, and enhance energy resilience in developing regions. These perceptions provide valuable guidance for renewable infrastructure planning and policy constitution across the same climatic regions.