Experimental And Theoretical Study On Thermal Performance Of Adding Phase Change Materials To Salt Gradient Solar Pond

With the environmental and traditional energy shortages becoming more and more serious,solar energy as the ideal clean energy gradually play a more and more important role in the social and economic development.As a way of solar energy utilization,the salt gradient solar pond has the function of absorbing and storing solar radiant energy,which is not only an important supplement to today's traditional energies,but also an important form of solar energy application in the future.In this paper,we take the salt gradient solar pond as the research object and analyze from two aspects of experiment and theory.The method of adding composite PCMcapsule in the salt gradient solar pond(SGSP)LCZ is proposed to improve the SGSP thermal performance.The composite PCM heat storage capsule with low cost and good thermal performance is prepared by a feasible method.Based on programmed temperature simulation of salt gradient solar pond experiment device,the effect of the heat storage capsule of adding composite PCM on the SGSP temperature field is studied,and the transient exergy lose analysis of the SGSP is carried out according to the experimental data.The numerical simulation model was established by using COMSOL Multiphysics and compared with the experimental results.The main work and conclusions are as follows:The composite PCM heat storage capsule with low cost and good thermal performance,which increased the heat transfer coefficient by 17.16%(55?melting process),18.84%(65?melting process)and 35.15 %(solidification process)compared with paraffin wax.The latent heat of paraffin wax decreases by about 10% after 5 times of cyclic phase change,but the steel wire does not affect the melting potential and melting point of paraffin.The experimental results show that: the maximum temperature difference between day and night in the salt gradient solar pond with PCM decreased by 2.87?and 2.53? respectively,and the transient exergy parameters increased by 13.52?and 20.46? respectively.It is indicated that the phase change characteristic of PCM couple with the salt gradient solar pond system,which has good buffering effect on the SGSP system,and positive meaning for thermal performance of SGSP thermal storage layer.Numerical results show that: the maximum temperature difference between day and night in the salt gradient solar pond with PCM decreased by 1.29 ? and 1.99 ? respectively.The experiment and numerical results have good consistency,which verifies the reasonable and correctness of the numerical model.And PCM can reduce the LCZ region temperature of the salt gradient solar pond,restrain the velocity of the flow.It has positive significance for the stability of the SGSP.