Integrative thermodynamic optimization of a vapor compression refrigeration system based on dynamic system responses

Yang, Sam; Ordóñez, Juan C.

doi:10.1016/j.applthermaleng.2018.02.088

Cited by 17 publications

(3 citation statements)

References 21 publications

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“…All the geometric dimensions and other data are presented in [9]. According to the literature review, previous models that address second law aspects of a system operation were developed for lumped parameter analysis [10], much alike the one presented in this work or the lumped parameter moving boundaries model [11], but focusing mainly on the pull-down operating regime. All models encountered in the literature review uses the integrative control volume approach for the system, including the one developed in this work, which can be justified by the fact that vapor compression cycles (VCS) are complex systems.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Irreversibility Analysis of Dual-Skin Chest-Freezer

Matsuda

Gardenghi

Tibiriçá

et al. 2022

Entropy

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In this work, a transient analysis of a dual-skin chest-freezer refrigeration system, operating with R290, is studied numerically with the purpose of performing the characterization of the system through the second law of thermodynamics. A mathematical model which accounts for refrigerant mass distribution inside the system is used. In addition, this work addresses the calculation of entropy generation and exergy destruction for characterizing the system performance during its operations. In order to validate the model, a comparison with measured experimental data is performed for both pull-down and on–off operations. The characterization of the system through the second law of thermodynamics is conducted using two different methods. One consists of a direct calculation of the entropy generation rate and the second one in the calculation of exergy destruction rate. The equivalence of these two methods is used as an indicative of the “correctness” of the performed calculations. The model results agree near 97% with the experimental data used in the comparisons. Entropy generation and exergy destruction results along time for the whole system and in its individual components are characterized with the second law. These results are very useful for improving refrigeration system design.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic Irreversibility Analysis of Dual-Skin Chest-Freezer

Matsuda

Gardenghi

Tibiriçá

et al. 2022

Entropy

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“…Regarding VCRSs, recent results on modeling and optimization considering single-objective functions can be found in [ 13 , 14 , 15 , 16 , 17 ] and multi-objective functions in [ 18 , 19 ]. By using energy, exergy, and economic analyses, Baakeem et al [ 14 ] theoretically investigated a multi-stage VCRS considering eight refrigerants (R407C, R22, R717, R134a, R1234yf, R1234ze(E), R410A, and R404A).…”

Section: Introductionmentioning

confidence: 99%

Superstructure-Based Optimization of Vapor Compression-Absorption Cascade Refrigeration Systems

Mussati

Morosuk

Mussati

2020

Entropy

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A system that combines a vapor compression refrigeration system (VCRS) with a vapor absorption refrigeration system (VARS) merges the advantages of both processes, resulting in a more cost-effective system. In such a cascade system, the electrical power for VCRS and the heat energy for VARS can be significantly reduced, resulting in a coefficient of performance (COP) value higher than the value of each system operating in standalone mode. A previously developed optimization model of a series flow double-effect H2O-LiBr VARS is extended to a superstructure-based optimization model to embed several possible configurations. This model is coupled to an R134a VCRS model. The problem consists in finding the optimal configuration of the cascade system and the sizes and operating conditions of all system components that minimize the total heat transfer area of the system, while satisfying given design specifications (evaporator temperature and refrigeration capacity of −17.0 °C and 50.0 kW, respectively), and using steam at 130 °C, by applying mathematical programming methods. The obtained configuration is different from those reported for combinations of double-effect H2O-LiBr VAR and VCR systems. The obtained optimal configuration is compared to the available data. The obtained total heat transfer area is around 7.3% smaller than that of the reference case.

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“…For the heat exchangers, the pressure loss was neglected, uniform external heat transfer properties, constant specific heat on sub-cooled and superheated regions, airflow uniformly distribute on the external surface and, all the heat transfer from the fluid is exchanged with the external air. Yang & Ordonez (2018) proposed a methodology to simulate, using the volume element method, proposed on Dilay et al (2014) and experimentally validated on Nunes et al (2015), and optimize the performance of vapor compression refrigeration systems, seeking the best combination of evaporator and condenser sizes. The higher and second law efficiencies and lower pull-down times were reached with smaller evaporator areas, where there was a little increasing on the compressor power and exergy destruction.…”

Section: Refrigeration Systems Modelingmentioning

confidence: 99%

Transient modeling of vapor compression refrigeration systems for domestic applications

Gardenghi¹

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The increasing on energetic efficiency of household vapor compression refrigeration systems brings about a substantial impact in the energy consumption: about 17% of the overall electricity consumption worldwide is attributed to the refrigeration sector (including air-conditioning), being 45% the residential demand. A case study showing it is the Brazilian panorama, where such systems are responsible for approximately 27% of the residential electric consumption, representing about 8% of the whole country's demand. This issue is intensified due the low thermodynamic efficiency presented by these products. Therefore, industry and research institutes are dedicating increasingly efforts and time to develop and apply solutions to promote advances on systems' operation. In this work, two mathematical models are presented: one based on a thermal analysis with the application of the first law of thermodynamics and other including the evaluation of the refrigerant mass distribution in the system. It is also developed an experimental procedure to calculate the thermal conductance and capacity of each component of a domestic refrigerator (compressor, condenser, capillary tube, evaporator, cabinet), which are necessary input data for the models. Experimental data describing the transient behavior of the refrigeration system are also obtained to validate the mathematical models. Two types of cabinets were studied: one with two compartments, operating with R134a and associated to constant speed and variable speed compressors; and a horizontal freezer, with one compartment and operating with R290. The simulation results follow the same experimental trends and are very satisfactory when compared to the transient and mean time experimental results. Two variable speed control strategies were evaluated, with gains up to 31% in consumption reduction by using them. An entropy generation analysis was performed for each system component and the overall system. Parametric analysis were conducted to identify the influence of ambient temperature, refrigerant charge and goods inside the compartments on the refrigeration system performance. The presented models are very appropriate for the transient simulation of vapor compression refrigeration systems for domestic applications.

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Integrative thermodynamic optimization of a vapor compression refrigeration system based on dynamic system responses

Cited by 17 publications

References 21 publications

Thermodynamic Irreversibility Analysis of Dual-Skin Chest-Freezer

Thermodynamic Irreversibility Analysis of Dual-Skin Chest-Freezer

Superstructure-Based Optimization of Vapor Compression-Absorption Cascade Refrigeration Systems

Transient modeling of vapor compression refrigeration systems for domestic applications

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