Review of transpired solar collectors: Heat and mass transfer mechanisms and enhancement, system integration, and performance assessment and optimisation

Abstract

This review paper presents an overview of transpired solar collectors (TSCs) - a clean energy technology that has gained considerable attention due to its potential to minimise building energy demand and contribute to achieving net zero emissions. The review is mainly focused on scrutinising the disparities in heat and mass transfer mechanisms, specifically the impact of homogeneous and inhomogeneous suction flow distributions on the TSC, encompassing performance improvement methods, performance assessment, and optimisation strategies for TSCs. The inconsistency between the theoretical and real-world performance of TSCs was observed, attributed to the high turbulence wind with non-uniform speed distribution and suction flow interactions with the main flow in the plenum. Corrugations on the absorber improved thermal performance but increased wind heat loss on the exterior surface, which could be mitigated by adding glazing to corrugated TSCs. The review highlighted the flexibility of integrating TSCs with other technologies, including coupling with separate phase change material (PCM) thermal energy storage units, which outperformed those placing the PCM plate into the plenum. Moreover, integrating TSCs with desiccant wheel cooling systems showed some interesting results in terms of cost and payback period, while integration with heat pump systems could reduce electricity consumption, but it was not recommended in cold climates. Exergetic analysis has been frequently used to determine thermodynamic losses of TSCs and it could provide a more accurate performance assessment when integrating TSCs with power generation systems. The review identified several research gaps in related study fields and provided recommendations, encompassing dimensionless analysis of the relationships between wind effect and heat transfer of TSC absorbers, the development of convective heat transfer correlations for TSC's absorber, and the exploration of cost-effective design and optimisation strategies for hybrid TSCs.