Performance evaluation of low-pressure turbine, turbo-compounding and air-Brayton cycle as engine waste heat recovery method

ABSTRACTThe synergistic combination of two promising engine architectures for future aero engines is presented. The first is the Composite Cycle Engine, which introduces a piston system in the high pressure part of the core engine, to utilise closed volume combustion and high temperature capability due to instationary operation. The second is the Intercooled Recuperated engine that employs recuperators to utilise waste heat from the core engine exhaust and intercooler to improve temperature levels for recuperation and to reduce compression work. Combinations of both architectures are presented and investigated for improvement potential with respect to specific fuel consumption, engine weight and fuel burn against a turbofan. The Composite Cycle alone provides a 15.6% fuel burn reduction against a turbofan. Options for adding intercooler were screened, and a benefit of up to 1.9% fuel burn could be shown for installation in front of a piston system through a significant, efficiency-neutral weight decrease. Waste heat can be utilised by means of classic recuperation to the entire core mass flow before the combustor, or alternatively on the turbine cooling bleed or a piston engine bypass flow that is mixed again with the main flow before the combustor. As further permutation, waste heat can be recovered either after the low pressure turbine – with or without sequential combustion – or between the high pressure and low pressure turbine. Waste heat recovery after the low pressure turbine was found to be not easily feasible or tied to high fuel burn penalties due to unfavourable temperature levels, even when using sequential combustion or intercooling. Feasible temperature levels could be obtained with inter-turbine waste heat recovery but always resulted in at least 0.3% higher fuel burn compared to the non-recuperated baseline under the given assumptions. Consequently, only the application of an intercooler appears to provide a considerable benefit for the examined thermodynamic conditions in the low fidelity analyses of various engine architecture combinations with the specific heat exchanger design. Since the obtained drawbacks of some waste heat utilisation concepts are small, innovative waste heat management concepts coupled with the further extension of the design space and the inclusion of higher fidelity models may achieve a benefit and motivate future investigations.

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Design methodology of a low pressure turbine for waste heat recovery via electric turbocompounding

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2016.06.142 ◽

2016 ◽

Vol 107 ◽

pp. 1166-1182 ◽

Cited By ~ 4

Author(s):

Aman M.I. Bin Mamat ◽

Ricardo F. Martinez-Botas ◽

Srithar Rajoo ◽

Liu Hao ◽

Alessandro Romagnoli

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Design Methodology ◽

Waste Heat ◽

Low Pressure ◽

Low Pressure Turbine

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Optimization of Supercritical CO2 Brayton Cycle for Simple Cycle Gas Turbines Exhaust Heat Recovery Using Genetic Algorithm

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2017-63696 ◽

2017 ◽

Author(s):

Akshay Khadse ◽

Lauren Blanchette ◽

Jayanta Kapat ◽

Subith Vasu ◽

Kareem Ahmed

Keyword(s):

Genetic Algorithm ◽

Mass Flow Rate ◽

Flow Rate ◽

Supercritical Co2 ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Brayton Cycle ◽

Exhaust Heat ◽

Exhaust Heat Recovery

For the application of waste heat recovery (WHR), supercritical CO2 (S-CO2) Brayton power cycles offer significant suitable advantages such as compactness, low capital cost and applicable to a broad range of heat source temperatures. The current study is focused on thermodynamic modelling and optimization of Recuperated (RC) and Recuperated Recompression (RRC) S-CO2 Brayton cycles for exhaust heat recovery from a next generation heavy duty simple cycle gas turbine using a genetic algorithm. The Genetic Algorithm (GA) is mainly based on bio-inspired operators such as crossover, mutation and selection. This non-gradient based algorithm yields a simultaneous optimization of key S-CO2 Brayton cycle decision variables such as turbine inlet temperature, pinch point temperature difference, compressor pressure ratio. It also outputs optimized mass flow rate of CO2 for the fixed mass flow rate and temperature of the exhaust gas. The main goal of the optimization is to maximize power out of the exhaust stream which makes it single objective optimization. The optimization is based on thermodynamic analysis with suitable practical assumptions which can be varied according to the need of user. Further the optimal cycle design points are presented for both RC and RRC configurations and comparison of net power output is established for waste heat recovery.

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Analytical Investigation of a Thermal-Supercharged Internal Combustion Engine Compounded With Organic Rankine Cycle for Waste Heat Recovery

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration Applications; Organic Rankine Cycle Power Systems ◽

10.1115/gt2017-65096 ◽

2017 ◽

Cited By ~ 1

Author(s):

Manuel Jiménez-Arreola ◽

Fabio Dal Magro ◽

Alessandro Romagnoli ◽

Meng Soon Chiong ◽

Srithar Rajoo ◽

...

Keyword(s):

Internal Combustion Engine ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Combustion Engine ◽

Rankine Cycle ◽

Internal Combustion ◽

Analytical Investigation ◽

Back Pressure ◽

Recovery Method

Waste heat recovery is seen as one of the key enablers in achieving powertrain of high efficiency. The exhaust waste heat from an internal combustion engine (ICE) is known to be nearly equivalent to its brake power. Any energy recovered from the waste heat, which otherwise would be discarded, may directly enhance the overall thermal efficiency of a powertrain. Rankine cycle (indirect-recovery method) has been a favorable mean of waste heat recovery due to its rather high power density yet imposing significantly lesser back pressure to the engine compared to a direct-recovery method. This paper presents the analytical investigation of a thermal-supercharged ICE compounded with Rankine cycle. This system removes the turbocharger turbine to further mitigate the exhaust back pressure to the engine, and the turbocharger compressor is powered by the waste heat recovered from the exhaust stream. Extra caution has been taken when exchanging the in/output parameters between the engine and Rankine cycle model to have a more realistic predictions. Such configuration improves the engine BSFC performance by 2.4–3.9%. Water, Benzene and R245fa are found to be equally good choice of working fluid for the Rankine cycle, and can further advance the BSFC performance by 4.0–4.8% despite running at minimum pressure setting. The off-design analyses suggested the operating pressure of Rankine cycle and its expander efficiency have the largest influence to the gross system performance.

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Waste heat recovery method for the air pre-purification system of an air separation unit

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2018.07.072 ◽

2018 ◽

Vol 143 ◽

pp. 123-129 ◽

Cited By ~ 3

Author(s):

L.G. Tong ◽

P. Zhang ◽

S.W. Yin ◽

P.K. Zhang ◽

C.P. Liu ◽

...

Keyword(s):

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Air Separation ◽

Separation Unit ◽

Recovery Method ◽

Purification System ◽

Air Separation Unit

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Performance assessment of steam Rankine cycle and sCO 2 Brayton cycle for waste heat recovery in a cement plant: A comparative study for supercritical fluids

International Journal of Energy Research ◽

10.1002/er.5138 ◽

2020 ◽

Vol 44 (15) ◽

pp. 12329-12343 ◽

Cited By ~ 1

Author(s):

Onder Kizilkan

Keyword(s):

Comparative Study ◽

Performance Assessment ◽

Supercritical Fluids ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Rankine Cycle ◽

Cement Plant ◽

Brayton Cycle

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Brayton Cycle Supercritical CO2 Power Block for Industrial Waste Heat Recovery

Volume 2: Combustion, Fuels, and Emissions; Renewable Energy: Solar and Wind; Inlets and Exhausts; Emerging Technologies: Hybrid Electric Propulsion and Alternate Power Generation; GT Operation and Maintenance; Materials and Manufacturing (Including Coatings, Composites, CMCs, Additive Manufacturing); Analytics and Digital Solutions for Gas Turbines/Rotating Machinery ◽

10.1115/gtindia2019-2347 ◽

2019 ◽

Author(s):

Sharath Sathish ◽

Pramod Kumar ◽

Logesh Nagarathinam ◽

Lokesh Swami ◽

Adi Narayana Namburi ◽

...

Keyword(s):

Industrial Waste ◽

Heat Recovery ◽

Waste Heat Recovery ◽

Waste Heat ◽

Rankine Cycle ◽

Coke Oven ◽

Brayton Cycle ◽

Steam Power ◽

Power Block ◽

Industrial Waste Heat

Abstract The Brayton cycle based supercritical CO2 (sCO2) power plant is an emerging technology with benefits such as; higher cycle efficiency, smaller component sizes, reduced plant footprint, lower water usage, etc. There exists a high potential for its applicability in waste heat recovery cycles, either as bottoming cycles for gas turbines in a combined cycle or for industrial waste heat recovery in process industries such as iron & steel, cement, paper, glass, textile, fertilizer and food manufacturing. Conventionally steam Rankine cycle is employed for the gas turbine and industrial waste heat recovery applications. The waste heat recovery from a coke oven plant in an iron & steel industry is considered in this paper due to the high temperature of the waste heat and the technological expertise that exists in the author’s company, which has supplied over 50 steam turbines/ power blocks across India for various steel plants. An effective comparison between steam Rankine cycle and sCO2 Brayton cycle is attempted with the vast experience of steam power block technology and extending the high pressure-high temperature steam turbine design practices to the sCO2 turbine while also introducing the design of sCO2 compressor. The paper begins with an analysis of sCO2 cycles, their configurations for waste heat recovery and its comparison to a working steam cycle producing 15 MW net power in a coke oven plant. The sCO2 turbomachinery design follows from the boundary conditions imposed by the cycle and iterated with the cycle analysis for design point convergence. The design of waste heat recovery heat exchanger and other heat exchangers of the sCO2 cycle are not in the scope of this analysis. The design emphasis is on the sCO2 compressor and turbine that make up the power block. This paper highlights the design of a sCO2 compressor and turbine beginning from the specific speed-specific diameter (Ns-Ds) charts, followed by the meanline design. Subsequently, a detailed performance map is generated. The relevance of this paper is underscored by the first of a kind design and comparative analysis of a Brayton sCO2 power block with a working Steam Power block for the waste heat recovery in the energy intensive iron and steel industry.

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