Evaporative Cooling on Building Surfaces Through a Microporous Hydrophobic Membrane

Abstract

In a greenhouse-constrained world, reductions in energy costs and increases in thermodynamic efficiency will be paramount in coming years. This current paper seeks to examine the material and theoretical performance of a novel microporous hydrophobic evaporative cooling membrane. Latent heat is removed through the evaporation of water through the membrane, where contaminants remain in solution as the hydrophobic membrane allows for passage of only water vapor. Through steady-state analysis of a proposed cooling system for building exterior walls, cooling capacity was shown to exceed cooling loads for large indoor areas. Candidate materials produced from recycled glass were examined through sintering, hydrophobing, and various processes to create material properties reliably as dictated by Matlab simulations. Real data acquired for Princeton, NJ from July 2011 was inputted to the simulations to quantify behavior of the system under real conditions. Even in the humid climate of New Jersey in July, the system could at the very least supplement a conventional cooling system, and at the most was demonstrated to effectively cool interior spaces to a 20 °C thermostat setpoint. This study fully examines the thermodynamics, heat transfer, and associated cooling ability of the proposed system.