energies Article Thermodynamic Study of a Combined Power and Refrigeration System for Low-Grade Heat Energy Source Saboora Khatoon , Nasser Mohammed A. Almefreji and Man-Hoe Kim *   Citation: Khatoon, S.; Almefreji, N.M.A.; Kim, M.-H. Thermodynamic Study of a Combined Power and Refrigeration System for Low-Grade Heat Energy Source. Energies 2021, 14, 410. https://doi.org/10.3390/ en14020410 Received: 2 December 2020 Accepted: 11 January 2021 Published: 13 January 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). School of Mechanical Engineering & IEDT, Kyungpook National University, Daegu 41566, Korea; s.khatoon@knu.ac.kr (S.K.); nasser6164@naver.com (N.M.A.A.) * Correspondence: manhoe.kim@knu.ac.kr; Tel./Fax: +82-53-950-5576 Abstract: This study focuses on the thermal performance analysis of an organic Rankine cycle powered vapor compression refrigeration cycle for a set of working fluids for each cycle, also known as a dual fluid system. Both cycles are coupled using a common shaft to maintain a constant transmission ratio of one. Eight working fluids have been studied for the vapor compression refrigeration cycle, and a total of sixty-four combinations of working fluids have been analyzed for the dual fluid combined cycle system. The analysis has been performed to achieve a temperature of −16 ◦ C for a set of condenser temperatures 34 ◦ C, 36 ◦ C, 38 ◦ C, and 40 ◦ C. For the desired temperature in the refrigeration cycle, the required work input, mass flow rate, and heat input for the organic Rankine cycle were determined systematically. Based on the manifestation of performance criteria, three working fluids (R123, R134a, and R245fa) were chosen for the refrigeration cycle and two (Propane and R245fa) were picked for the organic Rankine cycle. Further, a combination of R123 in the refrigeration cycle with propane in the Rankine cycle was scrutinized for their highest efficiency value of 16.48% with the corresponding highest coefficient of performance value of 2.85 at 40 ◦ C. Keywords: organic Rankine cycle; energy efficiency; refrigeration cycle; waste heat 1. Introduction To improve the energy efficiency in the industrial world, heat recovery technologies employing standalone and combined cycle configurations have been advanced and im- proved continuously. All the energy-related challenges covering the resources, demand, and supply, as well as their applications, have always been a high concern issue globally. Governments around the globe, in particular, from developed nations such as the US and UK, have constantly allocated substantial budgets at national and international levels to bring contemporary evaluations on relevant issues. The most recent examples include the independent assessment delivered by the UK Committee on Climate Change [1] and the International Energy Outlook 2018 [2] by the US Energy Information Administration. To specify the seriousness of energy-related issues, the projected world energy consumption will reach up to 736 quadrillion British thermal units (Btu) by 2040. This, in general, in- cludes an 18% increase in the industrial sector along with a 50% increase in total world energy consumption. The UK government has set a national target to accomplish (<20%) improvement in industrial energy efficiency by 2030 [1]. Action plans are being established by all governments, such as enabling innovation and improvement opportunities across the globe. Implementing thermally efficient practices and taking advantage of industrial waste heat are some examples of possible techniques to improve industrial energy efficiency. With the deployment of advanced technologies, low-grade heat has the potential in pro- ducing (a) electrical power; (b) electricity, heat, and cooling simultaneously; (c) water desalination as well as (d) hydrogen production. The integration of bottoming cycles with Energies 2021, 14, 410. https://doi.org/10.3390/en14020410 https://www.mdpi.com/journal/energies