Influence of graphene nanoplatelets dispersion in food graded heat transfer fluid on the performance of Non-Centrifugal cane sugar unit- a CFD approach

Abstract

Non-centrifugal cane sugar unitusing food-grade heat transfer oils to make excellent jaggery is an emerging technology. Thermophysical characteristics of such fluids are crucial for improving the system’s efficiency. Graphene nanoplatelets with low weight concentrations are dispersed into Sigma-thermic fluid (STF) to prepare nanofluids which is utilized as heat transfer oils in the NCCS unit. To envisage the potential of these fluids a numerical model is developed by validating the experimental results of STF. Firstly, experiments with STF at 20 lpm, 433 K, were conducted in the NCCS unit, which was fabricated in the laboratory. The results are agreed with the error of 1.14 %; further, the developed numerical model is employed to envisage the potential of STF based graphene nanofluids. Morphological graphene studies are conducted, and nanofluids with different weight concentrations are subsequently prepared. Experimentally measured nanofluid thermophysical characteristics are employed in the numerical model. Simulations are run until the bowl inner surface achieves concentrated sugar cane juice temperature. The effect of inlet temperature and concentration of nanoparticles on the sugar cane juice boiling time, bowl inner surface temperature, heat transfer rate, performance index ratio, thermohydraulic performance, and entropy generation is investigated. The results show that the Nusselt number increases with temperature, and the Nusselt number enhanced by 13.48 %, 22.18 %, and 30.09 % at temperatures of 413 K, 423 K, and 433 K, respectively compared to 403 K temperature for GrS0.3 %. Moreover, heat transfer is enhanced by 22.17 % with GrS0.3 % nanofluid compared to base fluid (STF) in the shortest duration, i.e., 7767 s. As the intake fluid temperature rises from 403 K to 413 K, 423 K, and 433 K, fluid friction irreversibilities are 13 %, 20 %, and 25 %.