Exergetic optimisation of a heat exchanger

Cornelissen, Renè; Hirs, Gerard

doi:10.1016/s0196-8904(96)00218-x

Cited by 35 publications

(14 citation statements)

References 6 publications

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“…A rectangular channel with aspect ratio of eight, gives the minimum entropy generation in laminar flow and turbulent flow according to Ratts and Raut [20]. Entropy generation and its minimisation have also been expressed for numerous heat exchangers and heat transfer surfaces: counterflow and nearly ideal heat exchanger neglecting fluid friction [24], tubular heat exchangers [25,26], heat exchangers restricted to perfect gas flows [27], balanced cross-flow recuperative plate-type heat exchangers with unmixed fluids [7]; and a parallel-plate ideal gas counterflow heat exchanger [28]. The ε-NTU method, based on the second law of thermodynamics, can be used to get the outlet temperatures and the total heat transfer from the hot fluid to the cold fluid [7,27,28].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic optimisation of the integrated design of a small-scale solar thermal Brayton cycle

Roux

Bello‐Ochende

Meyer

2011

Int. J. Energy Res.

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SUMMARYThe Brayton cycle's heat source does not need to be from combustion but can be extracted from solar energy. When a black cavity receiver is mounted at the focus of a parabolic dish concentrator, the reflected light is absorbed and converted into a heat source. The second law of thermodynamics and entropy generation minimisation are applied to optimise the geometries of the recuperator and receiver. The irreversibilities in the recuperative solar thermal Brayton cycle are mainly due to heat transfer across a finite temperature difference and fluid friction. In a small-scale open and direct solar thermal Brayton cycle with a micro-turbine operating at its highest compressor efficiency, the geometries of a cavity receiver and counterflow-plated recuperator can be optimised in such a way that the system produces maximum net power output. A modified cavity receiver is used in the analysis, and parabolic dish concentrator diameters of six to 18 metres are considered. Two cavity construction methods are compared. Results show that the maximum thermal efficiency of the system is a function of the solar concentrator diameter and choice of micro-turbine. The optimum receiver tube diameter is relatively large when compared with the receiver size. The optimum recuperator channel aspect ratio for the highest maximum net power output of a micro-turbine is a linear function of the system mass flow rate for a constant recuperator height. For a system operating at a relatively small mass flow rate, with a specific concentrator size, the optimum recuperator length is small. For the systems with the highest maximum net power output, the irreversibilities are spread throughout the system in such a way that the internal irreversibility rate is almost three times the external irreversibility rate.

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Section: Introductionmentioning

confidence: 99%

Thermodynamic optimisation of the integrated design of a small-scale solar thermal Brayton cycle

Roux

Bello‐Ochende

Meyer

2011

Int. J. Energy Res.

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“…Cornelissen and Hirs [105] did an exergetic optimisation of a balanced water-to-water counterflow heat exchanger by considering the irreversibilities due to pressure drop, due to temperature difference between the hot and the cold stream and also due to the production and construction of the heat exchanger. Heat loss to the environment and heat resistance of the tube walls were neglected.…”

Section: Recuperator or Heat Exchangermentioning

confidence: 99%

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

Roux

Bello‐Ochende

Meyer

2013

Renewable and Sustainable Energy Reviews

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Many studies have been published on the performance and optimisation of the Brayton cycle and solar thermal Brayton cycle showing the potential, merits and challenges of this technology. Solar thermal Brayton systems have potential to be used as power plants in many sun-drenched countries. It can be very competitive in terms of efficiency, cost and environmental impact. When designing a system such as a recuperative Brayton cycle there is always a compromise between allowing effective heat transfer and keeping pressure losses in components small. The high temperatures required in especially the receiver of the system presents a challenge in terms of irreversibilities due to heat loss. In this paper, the authors recommend the use of the total entropy generation minimisation method. This method can be applied for the modelling of a system and can serve as validation when compared with first-law modelling. The authors review various modelling perspectives required to develop an objective function for solar thermal power optimisation, including modelling of the sun as an exergy source, the Gouy-Stodola theorem and turbine modelling.With recommendations, the authors of this paper wish to clarify and simplify the optimisation and modelling of the solar thermal Brayton cycle for future work. The work is applicable to solar thermal studies in general but focuses on the small-scale recuperated solar thermal Brayton cycle.2

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“…The heat exchanger, a piece of heat and cold transfer equipment widely used in various aspects of industry, demands improvement in order to reduce its energy consumption and increase energy efficiency [1]. Among different types of heat exchangers, plate-fin heat exchangers (PFHEs) are regarded for excellent heat exchange capacity and compact size.…”

Section: Introductionmentioning

confidence: 99%

Irreversibility analysis for optimization design of plate fin heat exchangers using a multi-objective cuckoo search algorithm

Wang

2015

Energy Conversion and Management

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Exergetic optimisation of a heat exchanger

Cited by 35 publications

References 6 publications

Thermodynamic optimisation of the integrated design of a small-scale solar thermal Brayton cycle

Thermodynamic optimisation of the integrated design of a small-scale solar thermal Brayton cycle

A review on the thermodynamic optimisation and modelling of the solar thermal Brayton cycle

Irreversibility analysis for optimization design of plate fin heat exchangers using a multi-objective cuckoo search algorithm

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