Examination of the performance envelope of combined Rankine, Brayton and two parallel inverse Brayton cycles

Alabdoadaim, Mohamed; Agnew, Brian; Alaktiwi, A.

doi:10.1243/0957650041761883

Cited by 19 publications

(15 citation statements)

References 7 publications

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“…Alabdoadaim et al [10] investigated a combined Rankine, Brayton and two parallel inverted Brayton cycles, and found that the system had a maximum thermal efficiency of 54%, achieved by altering the expansion ratio of the second inverted Brayton cycle. Alabdoadaim et al [11] studied a combined Rankine, Brayton and inverse Brayton cycle and attained a maximum thermal efficiency of 57.7%.…”

Section: Figure 1: Inverted Brayton Cyclementioning

confidence: 99%

Experimental Investigation of an Inverted Brayton Cycle for Exhaust Gas Energy Recovery

Kennedy

Chen

Ceen

et al. 2018

Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines

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Exhaust gases from an internal combustion engine (ICE) contain approximately 30% of the total energy released from combustion of the fuel. In order to improve fuel economy and reduce emissions, there are a number of technologies available to recover some of the otherwise wasted energy. The inverted Brayton cycle (IBC) is one such technology. The purpose of the study is to conduct a parametric experimental investigation of the IBC. Hot air from a turbocharger test facility is used. The system is sized to operate using the exhaust gases produced by a 2 litre turbocharged engine at motorway cruise conditions. A number of parameters are investigated that impact the performance of the system such as turbine inlet temperature, system pressure drop and compressor inlet temperature. The results confirm that the output power is strongly affected by the turbine inlet temperature and system pressure drop. The study also highlights the packaging and performance advantages of using a 3D printed heat exchanger to reject the excess heat. Due to rotordynamic issues, the speed of the system was limited to 80,000 rpm rather than the target 120,000 rpm. However, the results show that the system can generate a specific work of up to 17 kJ/kg at 80,000 rpm. At full speed it is estimated that the system can develop approximately 47 kJ/kg, which represents a thermal efficiency of approximately 5%.

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Section: Figure 1: Inverted Brayton Cyclementioning

confidence: 99%

Experimental Investigation of an Inverted Brayton Cycle for Exhaust Gas Energy Recovery

Kennedy

Chen

Ceen

et al. 2018

Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines

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show abstract

“…The study of combined Brayton/Rankine cycle with the use of regenerators has been a point of focus for some researchers. Bejan et al (2012) showed that the path to improve the efficiency of regenerator, aiming the maximum heat transfer and minimum head loss, was to turn the current parallel channel Engenharia Térmica (Thermal Engineering), Vol. 16 • No.…”

Section: Introductionmentioning

confidence: 99%

“…In order to do that, it would be necessary to make appropriate use of the existing technologies, without the need of waiting for new technological development of turbines. Alabdoadaim et al (2004) investigated the performance of a big cycle composed of a Brayton, two reverse parallel Brayton and a Rankine cycle. The expansion pressure relation between the two reverse Brayton cycles was varied, considering values above the atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Analysis of a Combined Brayton/Rankine Cycle With Two Regenerators in Parallel

Santos

Fagundes

Santos

et al. 2017

RETERM

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This work presents a configuration of two regenerators in parallel for a power generation Brayton/Rankine cycle where the output power is 10 MW. The working fluids considered for the Brayton and Rankine cycles are air and water, respectively. The addition of a regenerator with the previous existing cycle of this kind resulted in the addition of a second-stage turbine in the Rankine cycle of reheat. The objective of this modification is to increase the thermal efficiency of the combined cycle. In order to examine the efficiency of the new configuration, it is performed a thermodynamic modelling and numerical simulations for both cases: a regular Brayton/Rankine cycle and the one with the proposed changes. At the end of the simulations, the two cycles are compared, and it is seen that the new configuration reaches a 0.9% higher efficiency. In addition, the vapor quality at the exit of the higher turbine is higher, reducing the required mass flow rate in 14%.

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“…The exergy analysis and optimization of the combined Brayton and inverse Brayton cycles were performed by Zhang et al [39]. Based on the combined Brayton and inverse Brayton cycles, Alabdoadaim et al [40][41][42] proposed its developed configurations including regenerative cycle and reheat cycle, and using two parallel inverse Brayton cycles as bottom cycles. They found that the system with regeneration attains higher heat efficiency than that of the base system, but with smaller work output based on the first law analysis.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle

Chen

Zhang

Sun

2012

Entropy

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A thermodynamic model of an open combined regenerative Brayton and inverse Brayton cycles with regeneration before the inverse cycle is established in this paper by using thermodynamic optimization theory. The flow processes of the working fluid with the pressure drops and the size constraint of the real power plant are modeled. There are 13 flow resistances encountered by the working fluid stream for the cycle model. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining nine flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, regenerator inlet and outlet, combustion chamber inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle, and control the air flow rate, the net power output and the thermal efficiency. The analytical formulae about the power output, efficiency and other coefficients are derived with 13 pressure drop losses. It is found that the combined cycle with regenerator can reach higher thermal efficiency but smaller power output than those of the base combined cycle at small compressor inlet relative pressure drop of the top cycle.

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Examination of the performance envelope of combined Rankine, Brayton and two parallel inverse Brayton cycles

Cited by 19 publications

References 7 publications

Experimental Investigation of an Inverted Brayton Cycle for Exhaust Gas Energy Recovery

Experimental Investigation of an Inverted Brayton Cycle for Exhaust Gas Energy Recovery

Analysis of a Combined Brayton/Rankine Cycle With Two Regenerators in Parallel

Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle

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