Thermodynamic analysis of irreversible closed Brayton engine cycles used in trigeneration systems

Dumitrașcu, Gheorghe; Feidt, Michel; Namat, A. R. J.; Grigorean, Ștefan; Horbaniuc, Bogdan

doi:10.1088/1757-899x/595/1/012022

Cited by 2 publications

(5 citation statements)

References 11 publications

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“…The first design of irreversible cycles can be performed using four imposed conditions see for instance [19]. These operational imposed conditions might be also combined, for instance constant specific power and constant energy efficiency for engines and constant heat input and constant energy efficiency for refrigeration units.…”

Section: Design Imposed Operational Conditionsmentioning

confidence: 99%

“…They have to define the internal main finite physical dimension parameters and after that to establish the dependence functions characterizing the performances of the irreversible cycle. For instance, [19] applied the four imposed operational conditions to evaluate the performances of a Joule-Brayton cycle working with two ideal gases, air and CO 2 . The main finite physical dimension parameter was the classical compression ratio, π C , and the dependence functions characterizing the performances of the irreversible cycle were:…”

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

“…Below are selected numerical results [19], see Figures 5-7, for imposed constant power 𝑤 = 500 kJ/kg and imposed irreversibility for graphs 1, 2, 3 and 4:…”

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

“…1: air, ηsC = 0.85, ηsT = 0.9, rp = 0.975; 2: air, ηsC = 0.8 and ηsT = 0.85, rp = 0.95 3: CO2, ηsC = 0.85, ηsT = 0.9, rp = 0.975; 4: CO2, ηsC = 0.8 and ηsT = 0.85, rp = 0.95 Below are selected numerical results [19], see Figures 5-7, for imposed constant power w = 500 kJ/kg and imposed irreversibility for graphs 1, 2, 3 and 4:…”

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

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Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

2021

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This paper develops simplifying entropic models of irreversible closed cycles. The entropic models involve the irreversible connections between external and internal main operational parameters with finite physical dimensions. The external parameters are the mean temperatures of external heat reservoirs, the heat transfers thermal conductance, and the heat transfer mean log temperatures differences. The internal involved parameters are the reference entropy of the cycle and the internal irreversibility number. The cycle’s design might use four possible operational constraints in order to find out the reference entropy. The internal irreversibility number allows the evaluation of the reversible heat output function of the reversible heat input. Thus the cycle entropy balance equation to design the trigeneration cycles only through external operational parameters might be involved. In designing trigeneration systems, they must know the requirements of all consumers of the useful energies delivered by the trigeneration system. The conclusions emphasize the complexity in designing and/or optimizing the irreversible trigeneration systems.

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Section: Design Imposed Operational Conditionsmentioning

confidence: 99%

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

“…Below are selected numerical results [19], see Figures 5-7, for imposed constant power 𝑤 = 500 kJ/kg and imposed irreversibility for graphs 1, 2, 3 and 4:…”

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

Section: Fpdt Internal Design Through Imposed Operational Conditionsmentioning

confidence: 99%

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Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

2021

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“…The preliminary design of irreversible cycles might be performed through four imposed operational conditions [14]: a. constant reference entropy, almost a theoretical approach, b. constant specific power, when the client requires this, c. constant energy efficiency, when we follow the maximum possible energy efficiency, and d. constant heat input when we have limited heat resources.…”

Section: The Design Imposed Operational Conditionsmentioning

confidence: 99%

Closed Irreversible Cycles Analysis Based on Finite Physical Dimensions Thermodynamics

Dumitrașcu

Feidt

Grigorean

2020

The First World Energies Forum—Current and Future Energy Issues

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The paper develops generalizing entropic approaches of irreversible closed cycles. The mathematical models of the irreversible engines (basic, with internal regeneration of the heat, cogeneration units) and of the refrigeration cycles were applied to four possible operating irreversible trigeneration cycles. The models involve the reference entropy, the number of internal irreversibility, the thermal conductance inventory, the proper temperatures of external heat reservoirs unifying the first law of thermodynamics and the linear heat transfer law, the mean log temperature differences, and four possible operational constraints, i.e., constant heat input, constant power, constant energy efficiency and constant reference entropy. The reference entropy is always the entropy variation rate of the working fluid during the reversible heat input process. The amount of internal irreversibility allows the evaluation of the heat output via the ratio of overall internal irreversible entropy generation and the reference entropy. The operational constraints allow the replacement of the reference entropy function of the finite physical dimension parameters, i.e., mean log temperature differences, thermal conductance inventory, and the proper external heat reservoir temperatures. The paper presents initially the number of internal irreversibility and the energy efficiency equations for engine and refrigeration cycles. At the limit, i.e., endoreversibility, we can re-obtain the endoreversible energy efficiency equation. The second part develops the influences between the imposed operational constraint and the finite physical dimensions parameters for the basic irreversible cycle. The third part is applying the mathematical models to four possible standalone trigeneration cycles. It was assumed that there are the required consumers of the all useful heat delivered by the trigeneration system. The design of trigeneration system must know the ratio of refrigeration rate to power, e.g., engine shaft power or useful power delivered directly to power consumers. The final discussions and conclusions emphasize the novelties and the complexity of interconnected irreversible trigeneration systems design/optimization.

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Thermodynamic analysis of irreversible closed Brayton engine cycles used in trigeneration systems

Cited by 2 publications

References 11 publications

Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

Closed Irreversible Cycles Analysis Based on Finite Physical Dimensions Thermodynamics

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