Title: Exergy-based evaluation of a waste heat driven polygeneration system with CO₂ as the working fluid

Authors: Jing Luo; Tatiana Morosuk; George Tsatsaronis; Bourhan Tashtoush

Addresses: Institute for Energy Engineering, Technische Universität Berlin, Marchstr. 18, 10587 Berlin, Germany ' Institute for Energy Engineering, Technische Universität Berlin, Marchstr. 18, 10587 Berlin, Germany ' Institute for Energy Engineering, Technische Universität Berlin, Marchstr. 18, 10587 Berlin, Germany ' Mechanical Engineering Department, Jordan University of Science and Technology, Ar Ramtha 3030, Jordan

Abstract: A waste heat driven polygeneration system that couples a supercritical power cycle with a transcritical refrigeration cycle is proposed and evaluated in this study. The stand-alone system using carbon dioxide as the working fluid produces power, refrigeration, and heating capacities simultaneously. Three scenarios of the system with different ambient temperatures (25-35°C) are optimised using exergoeconomic approach to obtain the lowest average cost of the products. The obtained results show that the average product cost is the highest ($113/GJ) for the scenario with the ambient temperature of 30°C, while the product cost is reduced to $82/GJ when the ambient temperature is 35°C. Moreover, the pressure for merging the sub-systems influences the performance of the system significantly, and the variations of the operating conditions differ among the scenarios by increasing the merging pressure. Besides, a multi-objective optimisation is implemented for supporting decision-makers to find the optimal solutions.

Keywords: polygeneration system; carbon dioxide; supercritical power cycle; transcritical refrigeration cycle; exergoeconomics; optimisation.

DOI: 10.1504/IJEX.2021.112035

International Journal of Exergy, 2021 Vol.34 No.1, pp.50 - 75

Received: 08 Nov 2019
Accepted: 30 May 2020
Published online: 23 Dec 2020 *

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