Modeling the influences of a phase change material and the Dufour effect on thermal performance of a salt gradient solar pond

Abstract

The influences of a layer of a Phase Change Material (PCM) and the Dufour effect on thermal performance of a Salt Gradient Solar Pond (SGSP) are investigated numerically. The enthalpy model is used to model the heat transfer in the PCM layer. The transfer equations in the SGSP are solved using the implicit Finite Volume Method, the Gauss method and the SIMPLE algorithm. The explicit Finite Volume Method is retained for the heat transfer equation of the PCM layer. The developed numerical model that has been validated experimentally and numerically is used to simulate the operation of the SGSP during ten days under the meteorological data of Tangier in Morocco. Two cases are considered for analysis; the first one is the SGSP without the PCM layer (case 1) and the second one is the SGSP with the PCM layer disposed at its bottom (case 2). The simulation results showed that the temperature, the thermal efficiency of the SGSP with the PCM layer are inferior and the amount of heat losses across the saline water free surface is superior to those of the SGSP without the PCM layer. Furthermore, the increase of the dimensionless Dufour coefficient from 0 to 0.8 leads to decrease, in case 1, the dimensionless temperature of the storage zone from 0.894 to 0.764 and the thermal storage efficiency from 37.41 % to 31.85 %. For the same range of variation of the dimensionless Dufour coefficient, the dimensionless temperature of the storage zone decreases from 0.800 to 0.688 and the thermal storage efficiency reduces from 33.32 % to 28.66 % in case 2. Thus, the Dufour effect is mitigated in the SGSP with the PCM compared to the SGSP without the PCM.