Multi-objective optimization of a cascade refrigeration system: Exergetic, economic, environmental, and inherent safety analysis

Abstract Inherently safer design is the new approach to maximize the overall safety of a process plant. This approach suggests some risk reduction strategies to be implemented in the early stages of design. In this paper a multi-objective optimization was performed considering economic, exergetic, and environmental aspects besides evaluation of the inherent safety level of a cascade refrigeration system. The capital costs, the processing costs, and the social cost due to CO 2 emission were considered to be included in the economic objective function. Exergetic efficiency of the plant was considered as the second objective function. As a measure of inherent safety level, Quantitative Risk Assessment (QRA) was performed to calculate total risk level of the cascade as the third objective function. Two cases (ammonia and propane) were considered to be compared as the refrigerant of the high temperature circuit. The achieved optimum solutions from the multi–objective optimization process were given as Pareto frontier. The ultimate optimal solution from available solutions on the Pareto optimal curve was selected using Decision-Makings approaches. NSGA-II algorithm was used to obtain Pareto optimal frontiers. Also, three decision-making approaches (TOPSIS, LINMAP, and Shannon’s entropy methods) were utilized to select the final optimum point. Considering continuous material release from the major equipment in the plant, flash and jet fire scenarios were considered for the CO 2 /C 3 H 8 cycle and toxic hazards were considered for the CO 2 /NH 3 cycle. The results showed no significant differences between CO 2 /NH 3 and CO 2 /C 3 H 8 with respect to economic and exergy efficiency objectives. But the CO 2 /NH 3 cycle was the inherently safer cascade system in comparison with the CO 2 /C 3 H 8 one. This is mainly due to the jet fire scenario for the CO 2 /C 3 H 8 cycle in which the effects are very severe in the farther distance as well as the areas close to the release point.

[1]  Haldun Dingeç,et al.  Thermoeconomic optimization of simple refrigerators , 1999 .

[2]  Genserik Reniers,et al.  Optimization procedure to select an inherently safer design scheme , 2015 .

[3]  Mehdi Mehrpooya,et al.  Thermodynamic and thermo-economic analysis and optimization of performance of irreversible four-temperature-level absorption refrigeration , 2014 .

[4]  Saeed Eini,et al.  Multi-objective optimization of industrial membrane SMR to produce syngas for Fischer-Tropsch production using NSGA-II and decision makings , 2016 .

[5]  Cezar O.R. Negrão,et al.  Thermoeconomic design and optimization of frost-free refrigerators , 2013 .

[6]  Fabio Rinaldi,et al.  Thermal–economic–environmental analysis and multi-objective optimization of an internal-reforming solid oxide fuel cell–gas turbine hybrid system , 2012 .

[7]  R. Selbas,et al.  Thermoeconomic optimization of subcooled and superheated vapor compression refrigeration cycle , 2006 .

[8]  Trevor Kletz.  Plant Design For Safety: A User-Friendly Approach , 1990 .

[9]  Gang Liu,et al.  Thermo-economic multi-objective optimization for a solar-dish Brayton system using NSGA-II and decision making , 2015 .

[10]  Jahar Sarkar,et al.  Optimization of a CO2–C3H8 cascade system for refrigeration and heating , 2005 .

[11]  Héctor Medina,et al.  Process design optimization and risk analysis , 2009 .

[12]  M. Sam Mannan,et al.  Development of inherently safer distillation systems , 2014 .

[13]  Ernest E. Ludwig,et al.  Applied Process Design for Chemical and Petrochemical Plants , 1977 .

[14]  M. Peters,et al.  Plant design and economics for chemical engineers / Max S. Peters, Klaus D. Timmerhaus, Ronald E. West , 2004 .

[15]  Surendra Singh Kachhwaha,et al.  NLP model based thermoeconomic optimization of vapor compression–absorption cascaded refrigeration system , 2015 .

[16]  Mehmet Kopac,et al.  Effect of saturation-temperature on the performance of a vapour-compression refrigeration-cycle working on different refrigerants using exergy method , 2006 .

[17]  F. Kreith,et al.  Principles of heat transfer , 1962 .

[18]  José Fernández-Seara,et al.  Theoretical analysis of a CO2–NH3 cascade refrigeration system for cooling applications at low temperatures , 2009 .

[19]  Juan M. Belman-Flores,et al.  NLP model of a LiBr–H2O absorption refrigeration system for the minimization of the annual operating cost , 2012 .

[20]  David Corne,et al.  The Pareto archived evolution strategy: a new baseline algorithm for Pareto multiobjective optimisation , 1999, Proceedings of the 1999 Congress on Evolutionary Computation-CEC99 (Cat. No. 99TH8406).

[21]  Daniel A. Crowl,et al.  Inherently safer chemical processes : a life cycle approach , 1997 .

[22]  Fabio Rinaldi,et al.  Exergetic, economic and environmental (3E) analyses, and multi-objective optimization of a CO2/NH3 cascade refrigeration system , 2014 .

[23]  Olcay Kincay,et al.  Thermoeconomic optimization of LiBr/H2O-R134a compression-absorption cascade refrigeration cycle , 2015 .

[24]  Fabio Rinaldi,et al.  4E analysis and multi-objective optimization of an integrated MCFC (molten carbonate fuel cell) and ORC (organic Rankine cycle) system , 2015 .

[25]  Kalyanmoy Deb,et al.  A fast and elitist multiobjective genetic algorithm: NSGA-II , 2002, IEEE Trans. Evol. Comput..

[26]  Kalyanmoy Deb,et al.  Visualizing multi-dimensional pareto-optimal fronts with a 3D virtual reality system , 2008, 2008 International Multiconference on Computer Science and Information Technology.

[27]  Ali Behbahaninia,et al.  Thermoeconomic optimization and exergy analysis of CO 2/NH 3 cascade refrigeration systems , 2011 .

[28]  Xing Ziwen,et al.  Experimental investigation on the performance of NH3/CO2 cascade refrigeration system with twin-screw compressor , 2009 .

[29]  Sepehr Sanaye,et al.  Thermal and economical optimization of air conditioning units with vapor compression refrigeration system , 2004 .