Effective utilization of natural convection via novel fin design & influence of enhanced viscosity due to carbon nano-particles in a solar cooling thermal storage system

Abstract

Abstract The present work proposes a novel fin design for high temperature solar cooling thermal storage system (TES) which utilizes natural convection more effectively. Different fin structures are investigated for quick heat absorption, and their thermal performance is compared with carbon nanoparticles based TES. It has been observed that the dispersion of carbon nanoparticles increase the effective viscosity of the nano-composite which severely deteriorates the natural convection heat transfer. Moreover, the effective viscosity correlations available in the literature are limited to spherical nanoparticles (without surfactant). Huge discrepancies would result using the same correlations for non-spherical particles like Graphene nanoplates (GNP) dispersed in the Phase change material (PCM). So, the empirical viscosity equations (at different concentration of GNP) are developed in the present work through a series of experimental trials carried on rotational Rheometer. Dynamic Differential scanning calorimetry (DSC) tests are performed to obtain the melting curve and specific heat correlations. The best eutectic PCM for double effect solar cooling system is suggested through systematic and comprehensive methodology using Multi attributes decision making (MADM) tools. The thermal performance of TES with a combination of both fins and GNP is further studied to propose a highly efficient storage system. The case study of a 23\u202fkW solar absorption chiller is also presented to analyze the cost reduction using the proposed fin design. It is concluded that decreasing fin size configuration gives the highest rate of heat transfer. A maximum reduction of 43% in the melting time is observed for TES with the novel finned configuration (at 5% GNP).