Parametric Study and Seasonal Simulations of a Solar Powered Adsorption Cooling System

Abstract

Models of solar-thermal powered adsorption cooling systems with and without heat recovery developed in TRNSYS and results from steady-periodic and seasonal simulations are presented. A normalized model is presented and used to process the seasonal TRNSYS results to investigate the coincidence between the solar-supplied cooling power and cooling load as the relative sizes of the cooling system and storage are varied. The normalized model yields a seasonal solar fraction and seasonal loss fraction (the excess solar-supplied cooling lost to the environment due to insufficient storage). Simulations were run for a zeolite-water adsorbent-refrigerant pair. Hourly weather data for Antalya, Turkey, were used for the transient simulations. Basic trends in performance were investigated as the following parameters were varied: system type (with or without heat recovery); incident radiation; maximum and minimum bed temperatures; condensation temperature; difference between condensation and minimum bed temperatures (bed excess temperature); bed's dead mass; collector type (flat plate vs. evacuated tube); cooling tower type (wet vs. dry); cooling system size; and, storage size. Results for the conditions explored include the following. Steady-periodic simulations show that the system's COP decreases with decreases in radiation and increases with minimum bed and condensation temperatures. Increasing the excess bed temperature increases the system's COP. Systems with an evacuated tube collector and wet cooling tower give higher system COP's than systems with a flat plate collector and dry cooling tower. The increase in system's COP due to decreasing the bed's dead mass and adding heat recovery is quantified. The solar fraction increases and the loss fraction decreases with increases in storage capacity, and both fractions decrease with increases in maximum bed temperature. The required evacuated tube collector area is smaller than the flat plate collector area while the required mass of adsorbent is independent of collector and adsorption cycle types. © 2009 by ABCM.