Performance analysis and optimization of direct contact condensation in a PCM fixed bed regenerator

Aim of this work is to model, optimize and characterize the design of a direct contact condenser utilizing spherical phase change material (PCM) elements as a packing medium in a solar driven humidification dehumidification (HDH) desalination plant Assuming local thermal non-equilibrium and departing from the continuous solid phase model, a simplified one-dimensional heat and mass transfer model has been developed and solved using interpenetration continua approach with volume averaging technique. The model has been validated against experimental data and was then used for further parametric analysis. Comparison with measurements showed good agreement with less than 3% of the fresh water production rate. The thermal behavior of the new condenser equipment is discussed and analyzed. Fundamental variables and critical parameters affecting the system performance such as the effect of condenser geometrical aspect ratio, packing size, air to water mass flow rate ratio, PCM thermal properties, and the effect of different types of packing media were studied. A system parameters analysis and characteristic guidelines for the optimum parameters and operation conditions have been obtained and will be presented thoroughly. Comparative performance of the system is clearly documented using PCM and Non-PCM packing elements. (C) 2011 Elsevier B.V. All rights reserved.