A Theoretical Model for Enhanced Passive Radiative Cooling by Utilizing Photon Chemical Potential

Abstract Passive radiative cooling has garnered significant attention due to its potential in energy conservation and environmental regulation.However the cooling power of passive radiative cooling is inherently limited by Planck' s law.Recent research found that positive photon chemical potential has the potential to enhance radiation power albeit it necessitates an active energy input.This study proposes a theoretical model integrating a heat engine and a thermal radiation diode (TRD) that can passively achieve positive photon chemical potential thereby enhanc ing radiative cooling power.The results demonstrate that the integrated system of TRD and thermoelectric generator (TEG) can effectively improve cooling power.Theoretical results indicate that the TRD-Carnot engine coupled sys tem has the potential to achieve a peak radiation power density of 606. 3 W/m when the Carnot engine operates at 300 K (hot reservoir) and 280 K (cold reservoir).The peak radiation power density has the potential to exceed the ideal blackbody radiation density at 300 K which is 459 W/m 2 .This study theoretically confirms that the synergistic effect between TRD and heat engine provides a novel approach for enhancing radiative cooling performance.