scholarly journals Hybrid Electric Propulsion

2020 ◽  
Vol 142 (06) ◽  
pp. 54-55
Author(s):  
Charles E. Lents
Keyword(s):  
Gas Turbine ◽  
Co2 Emissions ◽  
Electric Propulsion ◽  
Electric Energy ◽  
Time Frame ◽  
Battery Pack ◽  
Level Energy ◽  
System Architectures ◽  
Fuel Burn ◽  
Gas Turbine Cycle

Abstract Electrified propulsion holds the promise of reducing aviation’s CO2 emissions footprint through three means: access to green grid electric energy, improvements in aircraft performance through new airframe and propulsion system architectures and enabling further optimization of the gas turbine cycle. Charging an aircraft battery pack with green electric energy and using this energy to drive electric propulsors results in a zero emissions vehicle. This is practical for light aircraft and short missions. Boosting a Jet-A burning gas turbine with green electric energy (again stored in a ground charged battery), in either a parallel or series turbo-electric architecture can yield a net reduction in CO2 emissions, as long as the fuel burn required to carry the weight of a discharged battery pack does not overcome the reduction in fuel burn afforded by the ground charged battery. Several studies have indicated that a net savings is possible with cell level energy densities approach ∼ 500 whr/kg, a reasonable target for the 2030 time frame. Electrified propulsion can also enable unique aircraft configurations, employing a veryhigh efficiency prime mover (gas turbine) designed for running only a generator at peak efficiency, and/or distributing the propulsors throughout the aircraft, for improvement in L/D and propulsive efficiency.

Cycle Optimization Potential of Composite Cycle and Turbocompound Aero-Engines

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Felix Klein ◽  
Stephan Staudacher
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Exchange Process ◽  
Aircraft Engine ◽  
Time Frame ◽  
Fuel Burn ◽  
Component Efficiency ◽  
Low Efficiency ◽  
Aero Engines

Abstract Fair comparison of future aircraft engine concepts requires the assumption of similar technological risk and a transparent book keeping of losses. A 1000 km and a 7000 km flight mission of a single-aisle airplane similar to the Aribus A321neo LR have been used to compare composite cycle engines, turbocompound engines and advanced gas turbines as potential options for an entry-into-service time frame of 2050+. A 2035 technology gas turbine serves as reference. The cycle optimization has been carried out with a peak pressure ratio of 250 and a maximum cycle temperature of 2200 K at cruise as boundary conditions. With the associated heat loss and the low efficiency of the gas exchange process limiting piston component efficiency, the cycle optimization filtered out composite cycle concepts. Taking mission fuel burn (MFB) as the most relevant criterion, the highest MFB reduction of 13.7% compared to the 2035 reference gas turbine is demonstrated for an air-cooled turbocompound concept with additional combustion chamber. An intercooled, hectopressure gas turbine with pressure gain combustion achieves 20.6% reduction in MFB relative to the 2035 reference gas turbine.

Optimal Control and Energy Management for Hybrid Gas-Electric Propulsion

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Hanz Richter ◽  
Joseph W. Connolly ◽  
Donald L. Simon
Keyword(s):  
Optimal Control ◽  
Electric Propulsion ◽  
Electric Energy ◽  
Generic Model ◽  
Control Approach ◽  
Electric Energy Consumption ◽  
Speed Regulation ◽  
Fuel Burn ◽  
Energy Conversion And Storage ◽  
Linear State

Abstract The paper considers a generic model for a turbofan engine coupled to electromechanical (EM) elements used for energy conversion and storage in electric form. The electromechanical systems apply torque to the engine shafts, allowing for controllable power injection or extraction to and from the engine. The standard proportional-integral (PI) control law used to command fuel flow for turbofan speed regulation is maintained for compatibility with industry practices, leaving the electromechanical torque to be specified. The paper adopts an optimal control approach for this purpose, where a weighted combination of electric energy consumption and fuel consumption is minimized subject to the dynamics of the electrified propulsion system. The solution for the optimal torques is given by linear state feedback plus bias, with gains calculated numerically from engine linearization data. Energy balance equations are derived and used to guide the optimization, evaluate the resulting power distributions, and check for errors. Simulation studies are presented for a chop-burst transient and for a realistic flight mission profile with environmental input variations. The paper shows the economic advantage of operating the engine with the electrified components. Specifically, fuel burn can be reduced in exchange for electric energy, which must be replenished, but at lower cost.

System Architectures for Solid Oxide Fuel Cell-Based Auxiliary Power Units in Future Commercial Aircraft Applications

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
R. J. Braun ◽  
M. Gummalla ◽  
J. Yamanis
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Solid Oxide ◽  
Department Of Energy ◽  
Oxide Fuel ◽  
System Architectures ◽  
Auxiliary Power ◽  
Fuel Burn ◽  
Auxiliary Power Units

Recent advancements in fuel cell technology through the auspices of the Department of Energy, the National Aeronautics and Space Administration, and industry partners have set the stage for the use of solid oxide fuel cell (SOFC) power generation systems in aircraft applications. Conventional gas turbine auxiliary power units (APUs) account for 20% of airport ground-based emissions. Alleviating airport ground emissions will continue to be a challenge with increased air travel unless new technology is introduced. Mission fuel burn and emissions can be significantly reduced through optimal systems integration of aircraft and SOFC subsystems. This study examines the potential total aircraft mission benefits of tightly integrating SOFC hybrids with aircraft subsystems using United Technologies Corporation Integrated Total Aircraft Power Systems proprietary methodologies. Several system concepts for optimal integration of the SOFC stack with aircraft subsystems are presented and analyzed in terms of mission fuel burn for technologies commensurate with 2015 entry into service. The performance of various hybrid SOFC-APU system architectures is compared against an advanced gas turbine-based APU system. In addition to the merits of different system architectures, optimal SOFC system parameter selection is discussed. The results of the study indicate that despite the lower power density of SOFC-based APU systems, significant aircraft fuel burn (5–7%) and emission reductions (up to 70%) are possible. The majority of the fuel burn savings are realized during aircraft ground operations rather than in-flight mission segments due to the greater efficiency difference between the SOFC system and the advanced APU technology.

Multi-objective optimization of a recuperative gas turbine cycle using non-dominated sorting genetic algorithm

2011 ◽  
Vol 225 (8) ◽  
pp. 1041-1051 ◽  
Author(s):  
H Sayyaadi ◽  
H R Aminian
Keyword(s):  
Genetic Algorithm ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Mixed Integer ◽  
Design Stage ◽  
Tube Length ◽  
Pareto Optimal ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Gas Turbine Cycle

A regenerative gas turbine cycle with two particular tubular recuperative heat exchangers in parallel is considered for multi-objective optimization. It is assumed that tubular recuperative heat exchangers and its corresponding gas cycle are in design stage simultaneously. Three objective functions including the purchased equipment cost of recuperators, the unit cost rate of the generated power, and the exergetic efficiency of the gas cycle are considered simultaneously. Geometric specifications of the recuperator including tube length, tube outside/inside diameters, tube pitch, inside shell diameter, outer and inner tube limits of the tube bundle and the total number of disc and doughnut baffles, and main operating parameters of the gas cycle including the compressor pressure ratio, exhaust temperature of the combustion chamber and the air mass flowrate are considered as decision variables. Combination of these objectives anddecision variables with suitable engineering and physical constraints (including NO x and CO emission limitations) comprises a set of mixed integer non-linear problems. Optimization programming in MATLAB is performed using one of the most powerful and robust multi-objective optimization algorithms, namely non-dominated sorting genetic algorithm. This approach is applied to find a set of Pareto optimal solutions. Pareto optimal frontier is obtained, and a final optimal solution is selected in a decision-making process.

A chemically intercooled gas turbine cycle for recovery of low-temperature thermal energy

Energy ◽  
2006 ◽  
Vol 31 (10-11) ◽  
pp. 1554-1566 ◽  
Author(s):  
Hongguang Jin ◽  
Hui Hong ◽  
Ruixian Cai
Keyword(s):  
Low Temperature ◽  
Gas Turbine ◽  
Thermal Energy ◽  
Gas Turbine Cycle

Substantiation of the parameters and layout solutions for an energy conversion unit with a gas-turbine cycle in a nuclear power plant with HTGR

Atomic Energy ◽  
2005 ◽  
Vol 98 (1) ◽  
pp. 21-31 ◽  
Author(s):  
A. V. Vasyaev ◽  
V. F. Golovko ◽  
I. V. Dmitrieva ◽  
N. G. Kodochigov ◽  
N. G. Kuzavkov ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Energy Conversion ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Conversion Unit ◽  
Gas Turbine Cycle

scholarly journals Evaluation of the Climate Impact Reduction Potential of the Water-Enhanced Turbofan (WET) Concept

Aerospace ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 59
Author(s):  
Regina Pouzolz ◽  
Oliver Schmitz ◽  
Hermann Klingels
Keyword(s):  
Co2 Emissions ◽  
Aircraft Engine ◽  
Steam Injection ◽  
Climate Impact ◽  
Formation Mechanisms ◽  
Water Recovery ◽  
Impact Reduction ◽  
Fuel Burn ◽  
Starting Point ◽  
Reduction Of Co2

Aviation faces increasing pressure not only to reduce fuel burn, and; therefore, CO2 emissions, but also to provide technical solutions for an overall climate impact minimization. To combine both, a concept for the enhancement of an aircraft engine by steam injection with inflight water recovery is being developed. The so-called Water-Enhanced Turbofan (WET) concept promises a significant reduction of CO2 emissions, NOx emissions, and contrail formation. Representative missions for an A320-type aircraft using the proposed new engine were calculated. Applying a first-order one-dimensional climate assessment prospects the reduction of more than half of the Global Warming Potential over one hundred years, compared to an evolutionarily improved aero-engine. If CO2-neutrally produced sustainable aviation fuels are used, climate impact could be reduced by 93% compared to today’s aircraft. The evaluation is a first estimate of effects based on preliminary design studies and should provide a starting point for discussion in the scientific community, implying the need for research, especially on the formation mechanisms and radiation properties of potential contrails from the comparatively cold exhaust gases of the WET engine.

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