Modeling of daytime radiative cooling enhanced vapor-compression refrigeration systems

Daytime Radiative Cooling (DRC) technologies use surfaces with tailored spectral properties to dissipate heat through the atmospheric transparency window towards outer space, even under direct sunlight. This study develops a transient simulation model to assess the energy-saving potential of integrating DRC materials into a typical vapor-compression refrigeration system (VCRS) for a residential building. The system employs flat-plate radiative panels coated with DRC material to cool a heat transfer fluid in a closed-loop circuit. This cooled liquid then reduces the temperature of the VCRS refrigerant via a supplementary heat exchanger located downstream of the air-cooled condenser, thereby enhancing the seasonal energy efficiency ratio (SEER) and reducing energy consumption. A parametric analysis examines key parameters, including radiative panel area, subcooler size, and panel fluid flow rate. The system is simulated for Las Vegas, Riyadh, Madrid, and Turin using experimental hourly meteorological data to capture the spectrally varying effects of atmospheric radiation. Moreover, the performance of different DRC materials is evaluated by comparing spectral selective and broadband emitters with two commercial options. Results show significant energy savings in hot, arid climates - 46.1 kW hel mDRC-2 in Riyadh and 37.5 kW hel mDRC-2 in Las Vegas - and up to a 10.1 % reduction in electric energy consumption.