Comparative parametric analysis of solar adsorption cooling systems driven by evacuated tube and parabolic trough concentrators in hot arid climates

The growing global energy demand, especially for air conditioning in hot, dry climates such as the Middle East, necessitates clean technology alternatives to conventional vapor compression systems. This article presents a comprehensive parametric study comparing solar adsorption cooling systems comparing Evacuated Tube Collectors (ETCs) and Parabolic Trough Concentrators (PTCs) in a hot arid climate. Transient simulations for four peak days in July in Baghdad, Iraq, utilized a 9 kW silica gel/water chiller model in TRNSYS 18. Results indicate the PTC consistently achieved higher outlet temperatures (107.93 °C vs. 91.3 °C) and energy acquisition rates (peak 32.17 kW vs. 24.82 kW) than the ETC model. Increasing collector area was linearly proportional to higher Coefficient of Performance (COP) and operating hours. A 55 m² PTC system, for instance, maintained continuous COP of 0.70–0.75, while a 55 m² ETC achieved COP as high as 0.83. Although higher storage tank capacities reduced overall operating hours, PTC-driven chillers consistently had longer operated hours across tested tank capacities compared to ETCs. The techno-economic analysis shows that the ETC system enjoys both a lower levelized cost of cooling at 0.096 $/kWh and a significantly reduced simple payback period of 6.6 years compared with the PTC system, which scored 0.099 $/kWh and 12.9 years, respectively, hence giving it a clear economic advantage under the analyzed conditions.