Development of Emissive Porous Polymers and Parabolic Trough Underside Reflectors for Enhanced Radiative Cooling

Abstract

A trough-enhanced radiative cooling (RC) system was developed and experimentally evaluated to achieve high-efficiency passive cooling under real outdoor conditions. Polymer-based porous PVDF-HFP emitters with high solar reflectance and strong atmospheric emittance were fabricated and integrated with parabolic trough reflectors. Monte Carlo ray tracing and heat balance simulations were conducted to predict temperature performance under various solar irradiance and convection scenarios. The experimental results revealed stable sub-ambient cooling of 1.2–4.2 °C during the day and up to 4 °C at night, demonstrating consistent cooling even under partial cloud coverage. Numerical predictions agreed well with measurements, showing less than 1 °C deviation, indicating the model’s reliability in evaluating RC performance. The validated model enables predictive design and optimization of trough-integrated RC systems, while the findings highlight the potential of reflective geometries in enhancing cooling power and scalability for energy-efficient thermal management and sustainable building applications.