Faculty Publications

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    Aspen Plus simulation of NH3-H2O-NaOH and NH3-H2O-KOH ternary cycles
    (Elsevier Ltd, 2022) Kolapkar, G.; Sathyabhama, A.
    The NH3-H2O is the most frequently utilized refrigerant-absorbent binary mixture in the vapor absorption refrigeration system (VARS) for low-temperature applications, but this mixture has the disadvantage of rectification requirement. To overcome this disadvantage, the researchers suggested the addition of salt to the binary NH3-H2O mixture. In this paper, a simulation of the ternary NH3-H2O-salt mixtures implemented in the VARS is presented. The NaOH and KOH salts are selected in the mass fraction range of 0 to 30% with 50 and 55% NH3 massconcentrations. The Aspen Plus process tool has been used to perform the simulation study. The addition of NaOH and KOH salts to the binary NH3-H2O mixture leads to an increase in thecoefficient of performance (COP) of the VARS with a simultaneous reduction in the initial generator operating temperature. The decrease in the generator temperature is slightly higher after adding NaOH salt than that by adding the KOH salt. TheCOP of thecycle increases after adding salt up to 20% salt mass fraction and then starts decreasing. The rise in the evaporator temperature leads to a gradual rise in theCOP of the ternary NH3-H2O-saltcycles. TheCOP of the ternary NH3-H2O-NaOHcycle is greater than that of the ternary NH3-H2O-KOHcycle under the same operating conditions. © 2022
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    EFFECTS OF NANOREFRIGERANTS FOR REFRIGERATION SYSTEM: A REVIEW
    (Begell House Inc., 2023) Kumar, A.; Narendran, G.; Arumuga Perumal, A.P.
    In this article various nanorefrigerants have been critically reviewed towards the performance enhancement of the refrigeration system. Research has been more focused on the different techniques to prepare nanorefrigerants. This paper is an attempt to summarize all aspects of nanorefrigerants such as preparation, thermophysical properties, hydrodynamic study, boiling heat transfer, and performance of nanorefrigerants. It also discusses the effects of different nanoparticles on ther-mophysical properties. Nanorefrigerants are a special category of nanofluid, advanced nanotech-nology-based refrigerants that are stable mixtures of nanoparticles and base fluid, which improve thermophysical properties such as heat transfer and pressure drop and bring compactness to the system. This article presents an overview of improving thermal performance by using different nanoparticle blends with different base refrigerants. Further, influential parameters of nanopar-ticles and thermal performance are discussed. This paper also discusses the effects of different nanoparticles such as Al2O3, TiO2, CuO, carbon nanotubes (CNTs), etc., on thermophysical prop-erties. The present situation requires a robust system and refrigerants for required performance. Some refrigerants cannot be used directly. So, this paper deals with using nanorefrigerants for better system performance such as coefficient of performance (COP) enhancement, compressor work reduction, and energy efficiency. It is seen that the use of nanorefrigerants, or nanotechnology-based refrigerants, results in highly effective cooling and thus enhances the thermophysical properties of refrigeration systems. © 2023 by Begell House, Inc. www.begellhouse.com.
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    Effect of salt on the performance of ammonia absorption refrigeration cycle: A simulation study
    (Elsevier Ltd, 2024) Kolapkar, G.; Sathyabhama, A.
    To overcome the drawbacks associated with conventional binary mixtures (NH3-H2O and H2O-LiBr) in the vapor absorption refrigeration system (VARS), salt is added to the NH3-H2O mixture. The present simulation study analyzes the influence of adding LiBr and LiNO3 salts within a salt mass fraction range of 0 to 35% on the coefficient of performance (COP) of the NH3-H2O cycle. The simulations are conducted using Aspen Plus software. Furthermore, the influence of generator temperature on the COP and evaporator capacity of the ternary NH3-H2O-LiBr and NH3-H2O-LiNO3 cycles are also studied. The simulation results demonstrate that adding LiBr and LiNO3 salts improves the COP and reduces the initial temperature requirement in the generator of the VARS. Specifically, the NH3-H2O-LiBr cycle achieves the highest COP of 0.645 at an NH3 mass fraction of 55% and a LiBr mass fraction of 25%. This represents an 8.81% improvement compared to the COP of the NH3-H2O cycle. Similarly, the NH3-H2O-LiNO3 cycle exhibits the peak COP of 0.603 with the same NH3 mass fraction and LiNO3 mass fraction of 20%, which is 2.2% greater than the COP of the NH3-H2O cycle. Under similar operating conditions, the COP of the NH3-H2O-LiBr cycle is greater than that of the NH3-H2O-LiNO3 cycle. © 2024 Elsevier Ltd