Abstract
•Loading Al2O3 nano-scale particles into solar-assisted air handling unit.•Using Al2O3 into working fluid improved the annual collector efficiency up to 6.1%.•Integrating the solar system with AHU decreased the power usage by 17.9%.•Using nanofluid-based solar system led to energy-saving by 4700 .kWhJuly.
In summer, the ventilation requirements of the supply air in the air handling units (AHUs) are adjusted using reheating coils. The water temperature in reheating coils is in the range that can be integrated with a solar heating system.
In this study, the thermal behavior of nanofluid filled solar-assisted AHU was investigated. The first law of thermodynamics was developed considering two phases of vapor as well as air. Considering the Riyadh dew point temperature, vapor condensation was modeled in the cooling coil. Due to the time-dependent nature of solar radiation intensity, the energy, as well as continuity equations for the collector and stratified storage tank were approved.
The results showed that the use of Al2O3 nano-scale particles increased the loss coefficient (undesirable), but due to the enhancement in maximum efficiency (desirable), nanoparticles intensified the annual collector effectiveness up to 6.1%. In July, integrating a nanofluid-based solar system with AHU, the energy demand reduced by 4700 kWh, which was equivalent to 17.9% reduction in the heating coil load.
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