Various Criteria in Optimization of a Vapor Compression Refrigeration System

2010 ◽  
Author(s):  
Mostafa Nejatolahi ◽  
Hoseyn Sayaadi
Keyword(s):  
Pareto Frontier ◽  
Vapor Compression ◽  
Economic Criterion ◽  
Multi Objective ◽  
Total Product ◽  
Energy And Exergy ◽  
Vapor Compression Refrigeration ◽  
Exergy Analyses ◽  
Single Objective ◽  
Selection Of

A cooling tower assisted vapor compression refrigeration machine has been considered for optimization with multiple criteria. Two objective functions including the total exergy destruction of the system (as a thermodynamic criterion) and the total product cost of the system (as an economic criterion), have been considered simultaneously. A thermodynamic model based on the energy and exergy analyses and an economic model according to the Total Revenue Requirement (TRR) method have been presented. Three optimized systems including a single-objective thermodynamic optimized, a single-objective economic optimized and a multi-objective optimized are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final solution from the Pareto frontier has been presented. The exergetic and economic results obtained for three optimized systems have been compared and discussed. The results have shown that the multi-objective design more acceptably satisfies generalized engineering criteria than other two single-objective optimized designs.

Multi-Objective Pricing Optimization for a High-Speed Rail Network Under Competition

2019 ◽  
Vol 2673 (7) ◽  
pp. 215-226 ◽  
Author(s):  
Huizhuo Cao ◽  
Xuemei Li ◽  
Vikrant Vaze ◽  
Xueyan Li
Keyword(s):  
High Speed ◽  
Programming Model ◽  
Pareto Frontier ◽  
Multiple Objectives ◽  
Multi Objective Optimization ◽  
High Speed Rail ◽  
Multi Objective ◽  
Trade Offs ◽  
Conflicting Objectives ◽  
Single Objective

Multi-objective pricing of high-speed rail (HSR) passenger fares becomes a challenge when the HSR operator needs to deal with multiple conflicting objectives. Although many studies have tackled the challenge of calculating the optimal fares over railway networks, none of them focused on characterizing the trade-offs between multiple objectives under multi-modal competition. We formulate the multi-objective HSR fare optimization problem over a linear network by introducing the epsilon-constraint method within a bi-level programming model and develop an iterative algorithm to solve this model. This is the first HSR pricing study to use an epsilon-constraint methodology. We obtain two single-objective solutions and four multi-objective solutions and compare them on a variety of metrics. We also derive the Pareto frontier between the objectives of profit and passenger welfare to enable the operator to choose the best trade-off. Our results based on computational experiments with Beijing–Shanghai regional network provide several new insights. First, we find that small changes in fares can lead to a significant improvement in passenger welfare with no reduction in profitability under multi-objective optimization. Second, multi-objective optimization solutions show considerable improvements over the single-objective optimization solutions. Third, Pareto frontier enables decision-makers to make more informed decisions about choosing the best trade-offs. Overall, the explicit modeling of multiple objectives leads to better pricing solutions, which have the potential to guide pricing decisions for the HSR operators.

scholarly journals Energy and Exergy Analysis of Combined Organic Rankine Cycle-Single and Dual Evaporator Vapor Compression Refrigeration Cycle

2019 ◽  
Vol 9 (23) ◽  
pp. 5028 ◽  
Author(s):  
Pektezel ◽  
Acar
Keyword(s):  
Exergy Analysis ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Vapor Compression Refrigeration

This paper presents energy and exergy analysis of two vapor compression refrigeration cycles powered by organic Rankine cycle. Refrigeration cycle of combined system was designed with single and dual evaporators. R134a, R1234ze(E), R227ea, and R600a fluids were used as working fluids in combined systems. Influences of different parameters such as evaporator, condenser, boiler temperatures, and turbine and compressor isentropic efficiencies on COPsys and ƞex,sys were analyzed. Second law efficiency, degree of thermodynamic perfection, exergy destruction rate, and exergy destruction ratio were detected for each component in systems. R600a was determined as the most efficient working fluid for proposed systems. Both COPsys and ƞex,sys of combined ORC-single evaporator VCR cycle was detected to be higher than the system with dual evaporator.

scholarly journals Modeling and multi-objective optimization of an R450A vapor compression refrigeration system

2019 ◽  
Vol 100 ◽  
pp. 141-155 ◽  
Author(s):  
Alireza Zendehboudi ◽  
Adrián Mota-Babiloni ◽  
Pavel Makhnatch ◽  
R. Saidur ◽  
Sadiq M. Sait
Keyword(s):  
Vapor Compression ◽  
Refrigeration System ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Vapor Compression Refrigeration

Experimental evidence concerning the different behavior of energy and exergy performance indicators of refrigeration systems in transient regimes

2016 ◽  
Vol 41 (1) ◽  
Author(s):  
Elena Eugenia Vasilescu ◽  
Michel Feidt ◽  
Rahal Boussehain ◽  
Alexandru Dobrovicescu
Keyword(s):  
Exergy Analysis ◽  
Initial Temperature ◽  
Stationary Regime ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Transient Regimes ◽  
Energy And Exergy ◽  
Vapor Compression Refrigeration ◽  
Exergy Performance

AbstractThis article presents the results obtained from an energy-exergy analysis of a vapor compression refrigeration system during induced transient regimes. Using experimental data, exergy destruction as a function of time under the influence of some factors that perturb the stationary regime, such as deactivation of piston, variation of mass flow rate and initial temperature of cooled fluid, and diminution of the compressor rotation speed, was calculated. Under the perturbation, an antagonistic increase in the coefficient of performance and a decrease in exergy efficiency were noted.

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