The growing demand for sustainable energy conversion systems has motivated the development of more efficient solar thermal technologies. Conventional collectors using water or oxide-based nanofluids often suffer from limited heat-transfer capability, poor stability, and high exergetic losses under variable solar conditions. High-altitude regions such as Kabul—characterized by strong solar irradiance, low ambient temperatures, and reduced convective losses—provide ideal conditions for advanced nanofluid-based solar collectors; however, existing studies mainly address isolated energetic or exergetic aspects and lack an integrated sustainability evaluation. This work fills this gap by presenting the first comprehensive 5E (energy, exergy, economic, exergoeconomic, and exergoenvironmental) assessment of an evacuated-tube solar collector operating with molybdenum disulfide (Mos 2) /water nanofluid under mountainous climatic conditions. A closed-loop MATLAB–Fluent–EES framework is developed to quantify thermal–hydraulic interactions and sustainability indicators. Results show that at the optimal operating condition of 1 vol% MoS 2 and 0. 06 kg/s, the collector achieves an average 25% increase in thermal efficiency, 22% improvement in exergy efficiency, and nearly 375% enhancement in useful heat gain, while the levelized cost of energy (LCOE) decreases from 0. 108 to 0. 078 /kWh and the specific exergy cost drops to 0. 110 USD/kWh-exergy. Environmentally, the exergo-environmental efficiency improves by approximately 15% despite the small rise in pumping power. These results demonstrate that the MoS 2 /water nanofluid provides an effective, stable, and economically viable working medium for high-altitude solar-thermal systems and establishes a new benchmark for 5E-integrated collector design.
Smaisim et al. (2026) studied this question.