This is a systematic review paper that aims to discuss the performance enhancements of solar air heaters (SAHs) with the addition of sensible heat storage (SHS) and latent heat storage (LHS) systems. In light of the inherent intermittency of current solar energy availability, which restricts the operational time and effectiveness of conventional SAHs, this review examines how thermal energy storage (TES) can fill the intermittency gap between energy supply and demand, especially during off-sunshine periods.
The review technique is an extensive critical examination and comparative study of experimental, numerical and theoretical research conducted between 2015 and 2026, with special attention to the most important performance indicators, including thermal efficiency, exergy efficiency, operational extension and cost-effectiveness.
The results show that SHS integration, whether involving Therminol-55 or lava rock and sand or waste steel chips, can increase performance by a significant amount; thermal efficiencies of up to 78%–90.97% and exergy efficiencies to 27%–37.53%, and an increase in time of heat delivery of 1–3 h after the sun goes down. LHS systems that use phase change materials (PCMs) such as paraffin wax, with a few cases using nanoparticles (e.g. SiO2) or finned, are found to have better temperature stability, with extended operation of 1.5–3 h and thermal efficiencies up to 75.9%–90.97%, although there is a slight loss in 5%–7% efficiency during the charging phase due to energy uptake. It is concluded that SHS and LHS integrations have a substantial positive impact on the thermal performance, exergetic efficacy and operational duration of SAHs and hybrid or double-pass configurations tend to be the most effective. Moreover, such systems demonstrate economic and environmental advantages, such as smaller payback times (less than 0.65 years) and higher CO2 emissions (up to 9.23 t/year), highlighting their suitability for sustainable functions in space heating, drying and agricultural operations.
The originality of this review lies in its systematic, qualified synthesis of 2015–2026 experimental, numerical and theoretical investigations on SAH performance improvements particularly through SHS/LHS. By concentrating on key performance metrics like thermal and exergy efficiency, off-sun operating extension and cost-effectiveness – it associates how various storage materials and configurations (e.g. Therminol-55, rock-based media, PCMs like paraffin wax and cases with nanoparticles or finned designs) can impact both energy-quality indicators and time-delayed heat delivery. Accordingly, the innovative side of this paper is the structured assessment of how TES can bridge the supply–demand gap during intermittency and that storage/flow setups (including hybrid or double-pass designs) most reliably offer performance and sustainability advantages.
