Title: Energy and exergy optimisation of parallel flow direct and indirect fired triple effect vapour absorption systems

Authors: Md. Azhar; Mohammad Altamush Siddiqui

Addresses: Department of Mechanical Engineering, Maulana Mukhtar Ahmad Nadvi Technical Campus, Malegaon-423203, Maharashtra, India ' Department of Mechanical Engineering, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002, Uttar Pradesh, India

Abstract: In this study, optimisation of operating parameters (generator temperatures, concentrations, and solution distribution ratios) have been performed to achieve maximum thermodynamic performance and minimum energy consumption in the parallel flow triple effect direct and indirect-fired vapour absorption refrigeration systems. Energy and exergy analyses are considered for the formation of the objective function to optimise the above operating parameters. Moreover, comparison of performance parameters have been shown with parallel flow double effect, series flow double effect, and series flow triple effect cycles. After optimisation of triple effect parallel flow cycles, results show that coefficient of performance of both triple effect direct and indirect fired cycles are the same. While exergy performance of direct fired cycle is around 70 to 80% lower than indirect fired cycle. Moreover, COP of parallel flow triple effect cycle is 7 to 10% higher than its series flow configuration. Also, flow rate of gaseous fuels of parallel flow triple effect cycle require 5% less as compared to series flow. Moreover, exergy performance of parallel cycles was found to be around 9-11% better than series flow cycles, but at the expense of 5-10% higher inlet temperature of the main generator.

Keywords: triple effect; absorption system; parallel flow cycle; optimisation; direct fired; indirect fired; exergy analysis.

DOI: 10.1504/IJEX.2021.114090

International Journal of Exergy, 2021 Vol.34 No.4, pp.385 - 410

Received: 16 May 2020
Accepted: 05 Aug 2020

Published online: 08 Apr 2021 *

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