Conceptual design and analysis of a novel process for hydrogen liquefaction assisted by absorption precooling system Majid Aasadnia a , Mehdi Mehrpooya a, b, * a Department of renewable energies and environment, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran b Hydrogen and Fuel Cell Laboratory, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran article info Article history: Received 28 April 2018 Received in revised form 21 August 2018 Accepted 1 September 2018 Available online 11 September 2018 Keywords: Liquid hydrogen Hydrogen liqueﬁer Large-scale hydrogen liquefaction Mixed-refrigerant Cascade refrigeration Hybrid refrigeration abstract Hydrogen liquefaction processes have effective function in the hydrogen supply chain. However low efﬁciency and high liquefaction costs are still the most important concerns about the liquefaction plants. In this study a new conﬁguration for a hydrogen liqueﬁer process is proposed and energy-exergy analyzed. The production rate of the liquid hydrogen ðLH 2 Þ is 90 tons per day that can supply the required LH 2 of at least 90 k-180 k hydrogen vehicles in an urban area that results in the reduction of pollutions caused by carbon dioxide emission. The process is simulated in Aspen HYSYS simulator. In addition, it is optimized thorough a trial and error approach that is a functional and simple method of complicated systems analysis. The process includes a mixed refrigerant (MR) refrigeration cycle that precools feed gas hydrogen from 25  C temperature to 199:9  C temperature. A new MR is used in a cascade Joule-Brayton cycle that deep-cools the low-temperature gaseous hydrogen from 199:9  C temperature to 252:2  C temperature in the cryogenic section of the plant. The novel process involves also an absorption refrigeration system (ARS) that cools some hydrogen streams in the precooling and cryogenic sections of the process. The consumed energy per kilogram of produced LH 2 is achieved as 6:47 kWh. This quantity is 2:89 kWh in the ideal conditions. The exergy efﬁciency of the plant is evaluated to be 45.5% that is signiﬁcantly more than the exergy efﬁciency of the in operating hydrogen liqueﬁers in the world. The energy analysis reveals that the coefﬁcient of performance (COP) of the overall system is 0.2034. The achieved COP is a higher amount in compare to the other similar processes. A sensitivity analysis is done to show the effect of the various operation conditions of the process on the features of the plant. Accordingly, the optimum mass ﬂow of the ARS is determined as 207 kg=s for the proposed conﬁguration. As well as, the effect of the change in the temperature approach of the heat exchangers and the changes in the adiabatic efﬁciency of the compressors and expanders on the SEC, COP, and the exergy efﬁciency of the overall plant is discussed. Furthermore, ﬁnancial analysis of the plant estimates the capital expenditures (CAPEX), energy expenditures (EEX), and operational and maintenance ex- penditures (OMEX) as 25413 V 2000 , 7370 V 2000 , and 2033 V 2000 respectively. These can be specially improved be improving of the exergy efﬁciency of the plant. The results implicates that the proposed conﬁguration has better performance indicators than the in-service liqueﬁers. Therefore, LHL plant manufacturer can be considered it in the design and development of new plants. As well as, researchers may utilize its operating conditions to improve the proposed processes. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Hydrogen can be considered as a clean energy source and can be produced from various renewable and nonrenewable sources (Aghaie et al., 2016)(Mehrpooya et al., 2017a)(Mohammadi and Mehrpooya, 2018). From chemical and nuclear fuels, LH 2 is the best fuel among chemical fuels (Hoffman, 1994). Accordingly, it has a high energy density or energy storage capacity per unit mass, versus gaseous hydrogen. As a matter of fact, gaseous hydrogen transportation requires high-pressure bulky storage tanks that are not feasible because of vessel resistance (Trevisani et al., 2007). However, special storage tanks containing LH 2 may be addressed the transportation problem, especially at long distances (Yang and * Corresponding author. Renewable Energies Department, Faculty of New Sci- ences and Technologies, University of Tehran, Tehran, Iran. E-mail address: mehrpoya@ut.ac.ir (M. Mehrpooya). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2018.09.001 0959-6526/© 2018 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 205 (2018) 565e588