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Research Papers: Gas Turbines: Cycle Innovations

The Benefits of an Inverted Brayton Bottoming Cycle as an Alternative to Turbocompounding

[+] Author and Article Information
Colin D. Copeland

Department of Mechanical Engineering,
University of Bath,
Bath BA2 7AY, UK
e-mail: C.D.Copeland@bath.ac.uk

Zhihang Chen

Department of Mechanical Engineering,
University of Bath,
Bath BA2 7AY, UK
e-mail: z.chen3@bath.ac.uk

Contributed by the Cycle Innovations Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 23, 2015; final manuscript received October 12, 2015; published online December 4, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 138(7), 071701 (Dec 04, 2015) (11 pages) Paper No: GTP-15-1374; doi: 10.1115/1.4031790 History: Received July 23, 2015; Revised October 12, 2015

The exhaust gas from an internal combustion engine contains approximately 30% of the thermal energy of combustion. Waste heat-recovery systems aim to reclaim a proportion of this energy in a bottoming thermodynamic cycle to raise the overall system thermal efficiency. The inverted Brayton cycle (IBC) considered as a potential exhaust-gas heat-recovery system is a little-studied approach, especially when applied to small automotive power plants. Hence, a model of an air-standard, irreversible Otto cycle and the IBC using finite-time thermodynamics (FTT) is presented to study heat recovery applied to an automotive internal combustion engine. The other two alternatives power cycles, the pressurized Brayton cycle and the turbocompounding system (TS), are compared with the IBC to specify the strengths and weaknesses of three alternative cycles. In the current paper, an irreversible Otto-cycle model with an array of losses is used as a base for the bottoming cycle. The deviation of the turbomachinery from the idealized behavior is described by the isentropic component efficiencies. The performance of the system as defined as the specific power output and thermal efficiency is considered using parametric studies. The results show that the performance of the IBC can be positively affected by five critical parameters—the number of compression stages, the cycle inlet temperature and pressure, the isentropic efficiency of the turbomachinery, and the effectiveness of the heat exchanger. There exists an optimum pressure ratio across the IBC turbine that delivers the maximum specific power. In view of the specific power, installing a single-stage of the IBC appears to be the best balance between performance and complexity. Three alternative cycles are compared in terms of the thermal efficiency. The results indicate that the pressurized and IBCs can improve the performance of the turbocharged engine (TCE) only when the turbomachinery efficiencies are higher than a value which changes with the operating condition. High performance of the IBC turbomachinery is required to ensure that the TCE with the IBC is superior to that with TS.

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References

Frost, T. , Anderson, A. , and Agnew, B. , 1997, “ A Hybrid Gas Turbine Cycle (Brayton/Ericsson): An Alternative to Conventional Combined Gas and Steam Turbine Power Plant,” Proc. Inst. Mech. Eng., Part A, 211(2), pp. 121–131. [CrossRef]
Zheng, J. , Sun, F. , Chen, L. , and Wu, C. , 2001, “ Exergy Analysis for a Braysson Cycle,” Exergy Int. J., 1(1), pp. 41–45. [CrossRef]
Tyagi, S. K. , Zhou, Y. , and Chen, J. , 2004, “ Optimum Criteria on the Performance of an Irreversible Braysson Heat Engine Based on the New Thermoeconomic Approach,” Entropy, 6(2), pp. 244–256. [CrossRef]
Zheng, J. , Chen, L. , Sun, F. , and Wu, C. , 2002, “ Powers and Efficiency Performance of an Endoreversible Braysson Cycle,” Int. J. Therm. Sci., 41(2), pp. 201–205. [CrossRef]
Zheng, T. , Chen, L. , Sun, F. , and Wu, C. , 2002, “ Power, Power Density and Efficiency Optimization of an Endoreversible Braysson Cycle,” Exergy Int. J., 2(4), pp. 380–386. [CrossRef]
Zhou, Y. , Tyagi, S. , and Chen, J. , 2004, “ Performance Analysis and Optimum Criteria of an Irreversible Braysson Heat Engine,” Int. J. Therm. Sci., 43(11), pp. 1101–1106. [CrossRef]
Agnew, B. , Anderson, A. , Potts, I. , Frost, T. , and Alabdoadaim, M. , 2003, “ Simulation of Combined Brayton and Inverse Brayton Cycles,” Appl. Therm. Eng., 23(8), pp. 953–963. [CrossRef]
Fujii, S. , Kaneko, K. , Otani, K. , and Tsujikawa, Y. , 2001, “ Mirror Gas Turbines: A Newly Proposed Method of Exhaust Heat Recovery,” ASME J. Eng. Gas Turbines Power, 123(3), pp. 481–486. [CrossRef]
Alabdoadaim, M. , Agnew, B. , and Potts, I. , 2006, “ Performance Analysis of Combined Brayton and Inverse Brayton Cycles and Developed Configurations,” Appl. Therm. Eng., 26(14), pp. 1448–1454. [CrossRef]
Besarati, S. , Atashkari, K. , Jamali, A. , Hajiloo, A. , and Nariman-Zadeh, N. , 2010, “ Multi-Objective Thermodynamic Optimization of Combined Brayton and Inverse Brayton Cycles Using Genetic Algorithms,” Energy Convers. Manage., 51(1), pp. 212–217. [CrossRef]
Bianchi, M. , di Montenegro, G. N. , Peretto, A. , and Spina, P. , “ A Feasibility Study of Inverted Brayton Cycle for Gas Turbine Repowering,” ASME Paper No. GT2003-38186.
Zhang, W. , Chen, L. , and Sun, F. , 2009, “ Power and Efficiency Optimization for Combined Brayton and Inverse Brayton Cycles,” Appl. Therm. Eng., 29(14), pp. 2885–2894. [CrossRef]
Zhang, Z. , Chen, L. , and Sun, F. , 2012, “ Energy Performance Optimization of Combined Brayton and Two Parallel Inverse Brayton Cycles With Regeneration Before the Inverse Cycles,” Sci. Iran., 19(5), pp. 1279–1287. [CrossRef]
Zhang, Z. , Chen, L. , and Sun, F. , 2012, “ Exergy Analysis for Combined Regenerative Brayton and Inverse Brayton Cycles,” Int. J. Energy Environ., 3(5), pp. 715–730.
Bailey, M. M. , 1985, “ Comparative Evaluation of Three Alternative Power Cycles for Waste Heat Recovery From the Exhaust of Adiabatic Diesel Engines,” NASA Lewis Research Center, Cleveland, OH, Report No. NASA TM-86953.
Ge, Y. , Chen, L. , and Sun, F. , 2008, “ Finite-Time Thermodynamic Modelling and Analysis of an Irreversible Otto-Cycle,” Appl. Energy, 85(7), pp. 618–624. [CrossRef]
Huleihil, M. , 2011, “ Effects of Pressure Drops on the Performance Characteristics of Air Standard Otto Cycle,” Phys. Res. Int., 2011, p. 496057. [CrossRef]
Mehta, H. B. , and Bharti, O. S. , “ Performance Analysis of an Irreversible Otto Cycle Using Finite Time Thermodynamics,” World Congress on Engineering, London, July 1–3.
Bejan, A. , 1988, “ Theory of Heat Transfer-Irreversible Power Plants,” Int. J. Heat Mass Transfer, 31(6), pp. 1211–1219. [CrossRef]
Kaneko, K. , Ohtani, K. , Tsujikawa, Y. , and Fujii, S. , 2004, “ Utilization of the Cryogenic Exergy of LNG by a Mirror Gas-Turbine,” Appl. Energy, 79(4), pp. 355–369. [CrossRef]
Hu, B. , Brace, C. , Akehurst, S. , Copeland, C. , and Turner, J. W. G. , 2014, “ 1-D Simulation Study of Divided Exhaust Period for a Highly Downsized Turbocharged SI Engine-Scavenge Valve Optimization,” SAE1 Technical Paper No. 2014-01-2550.

Figures

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Fig. 1

(Top left) Turbocharging and turbocompounding; (top right) pressurized Brayton; and (bottom) inverted Brayton

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Fig. 2

Schematic of the TCE with the IBC

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Fig. 3

Temperature and entropy diagram of a TCE with three stages compression of IBC

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Fig. 4

P–V diagram of the air-standard Otto cycle

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Fig. 5

The system-specific work output as a function of subatmospheric pressure and number of compression stages in the IBC

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Fig. 6

Effect of compression stages and subatmospheric pressure on the thermal efficiency

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Fig. 7

The specific work output variation depending on the bottoming turbine inlet temperature and subatmospheric pressure

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Fig. 8

The thermal efficiency variation depending on the bottoming turbine inlet temperature and subatmospheric pressure

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Fig. 9

IBC performance versus subatmospheric pressure plotted for different values of turbomachinery efficiency (turbine and compressor—ηit  and ηic: (a) 0.9 and 0.85; (b) 0.85 and 0.8; (c) 0.8 and 0.75; (d) 0.75 and 0.7; and (e) 0.7 and 0.65)

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Fig. 10

PIBC* –  ηIBC  curves varying with p6  and rt

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Fig. 11

PIBC* –  ηIBC  curves varying with plow  and ηex 

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Fig. 12

Schematic of the TCE with the pressurized Brayton cycle

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Fig. 13

Comparison of three alternative power cycles at different values of the turbomachinery efficiency, heat exchanger effectiveness, and turbine pressure ratio

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Fig. 14

The efficiency of TCE with various stages IBC versus IBC turbomachinery efficiency

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Fig. 15

The efficiency of TCE with various stages IBC versus pressure drop in the heat exchanger

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