Department of Mechanical engineering

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Author: search.filters.author.Dasgupta, Mani SankarSubject: search.filters.subject.CFD

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    CFD supported thermodynamic analysis of a CO2 pressure exchanger based refrigeration system for supermarkets
    (Elsevier, 2023-04) Dasgupta, Mani Sankar
    This manuscript presents a method to thermodynamically model a pressure exchanger device. CFD-based model of a rotary energy recovery device used in desalination process is developed and validated with published experimental data with a maximum deviation of 5.19%. The dimensionality of the validated model was reduced to investigate the potential of the pressure exchanger device operating with CO2 as the working fluid. Based on the data obtained from several numerical experiments, two correlations were developed, by means of non-linear regression analysis, for estimating the pressure lift generated by the device as a function of inlet velocity of high pressure fluid (0.5 – 3 m/s), rotor speed (500 – 3000 rpm), receiver pressure (25 – 40 bar) and gas-cooler pressure (90 – 120 bar). The correlations were found to be within acceptable error margin. The pressure lift generated by the pressure exchanger was found to be directly proportional to the inlet velocity of the high pressure fluid and inverse proportionality to the rotor speed. The developed correlations are used to evaluate the thermodynamic performance of a multi evaporator supermarket refrigeration system integrated with pressure exchanger to a conventional parallel compression system and a published multi-ejector system in the ambient temperature range of 30 to 40°C. The pressure exchanger based system was found to outperform the parallel compression as well as the multi-ejector system and demonstrate significant energy savings.
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    CFD Modeling of a Scroll Work Recovery Expander for Trans-critical CO2 Refrigeration System
    (Elsevier, 2017-03) Dasgupta, Mani Sankar
    Fluid flow characteristics of CO2, as a refrigerant in a scroll work recovery expander is investigated using CFD approach. A 2D simulation is carried out, adopting dynamic mesh in Ansys environment (FLUENT) and turbulent flow in the scroll expander is modeled using PISO algorithm. Changing behavior of CO2 during suction, expansion and exhaust process in a scroll involute are captured at four rotation angles. Study is carried out for a commercially available geometry. Pressure and velocity distribution of CO2 along the involute profile for the trans-critical expansion process is presented. It is observed that the leakage space can be further optimized to reduce the internal leakage of CO2 which can increase the overall efficiency of the scroll expander.