An Intercooled Recuperative Aero Engine for Regional Jets

2014 ◽  
Author(s):  
Maximilian Kormann ◽  
Reinhold Schaber
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Thermodynamic Efficiency ◽  
Parameter Study ◽  
Nox Emissions ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Aero Engines ◽  
Regional Jets

Flying requires a high power density in the propulsion system. Currently only turbofan engines can provide the required power at a low system mass. To counter a potential negative impact of aircraft emissions on global climate, the agreement Flightpath 50, created by European research establishments and industries, has set the target to reduce overall CO2 emissions from the year 2000 to 2050 by 75 %. In contrast, the air traffic volume has been growing constantly since the 1980s and will be growing further. Hence the fuel burn of aero engines has to be reduced to reach the Flightpath 50 target. High-end component technology has nearly exhausted full potential in the improvement of conventional turbofan engines. Further significant progress can only be achieved by new engine concepts. The geared turbofan has proven the feasibility of this approach. The introduction of a gear allows the IPC and LPT to run at more suitable speeds with the consequence of a lower stage count compared to conventional turbofans. According to Pratt&Whitney this will reduce the fuel burn by ”15–16% versus today’s best engines” [1]. As a next step towards Flightpath 50 MTU Aero Engines AG envisioned the Intercooled Recuperative Aero Engine (IRA) for long-haul application. This concept increases the thermodynamic efficiency of the core engine by utilizing two heat exchangers: an intercooler reduces the work which is necessary for the compression. A recuperator transfers heat of the exhaust gas to the compressed gas entering the burner. In long-haul aircraft the increased engine mass due to the heat exchangers has a lower influence on the fuel burn. To broaden the research, this paper investigates the application of the IRA for regional jets. An extensive predesign parameter study was performed to find the optimal IRA configuration for regional jets. Not only has fuel consumption been taken into consideration, additionally the influence of the increased weight of the IRA has been included. In optimum, the fuel burn on a regional mission according to this study could be reduced in the order of 1–2%. However, the overall pressure ratio is much lower compared to modern turbofan engines, which leads to relatively low NOx emissions. It allows the introduction of Lean Premixed Prevaporized (LPP) burner technology, promising an additional significant reduction in NOx emissions compared to modern turbofan engines. Compared to a longhaul application the heat exchangers are not a scaled version but the result of a cycle optimization considering the available space. The paper also gives an outlook for an innovative three dimensional heat exchanger. The novel heat exchanger arrangement promises a better integration into the annulus at turbine exit and less aerodynamical pressure losses due to 3D-effects.

scholarly journals Assessment of CO2 and NOx Emissions in Intercooled Pulsed Detonation Turbofan Engines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Carlos Xisto ◽  
Olivier Petit ◽  
Tomas Grönstedt ◽  
Anders Lundbladh
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Nox Emissions ◽  
Simulation Tool ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Pulsed Detonation ◽  
Detonation Combustion ◽  
Aero Engine ◽  
Computational Fluid Dynamics Cfd

In the present paper, the synergistic combination of intercooling with pulsed detonation combustion is analyzed concerning its contribution to NOx and CO2 emissions. CO2 is directly proportional to fuel burn and can, therefore, be reduced by improving specific fuel consumption (SFC) and reducing engine weight and nacelle drag. A model predicting NOx generation per unit of fuel for pulsed detonation combustors (PDCs), operating with jet-A fuel, is developed and integrated within Chalmers University's gas turbine simulation tool GESTPAN. The model is constructed using computational fluid dynamics (CFD) data obtained for different combustor inlet pressure, temperature, and equivalence ratio levels. The NOx model supports the quantification of the trade-off between CO2 and NOx emissions in a 2050 geared turbofan architecture incorporating intercooling and pulsed detonation combustion and operating at pressures and temperatures of interest in gas turbine technology for aero-engine civil applications.

scholarly journals Assessment of CO2 and NOx Emissions in Intercooled Pulsed Detonation Turbofan Engines

2018 ◽  
Author(s):  
Carlos Xisto ◽  
Olivier Petit ◽  
Tomas Grönstedt ◽  
Anders Lundbladh
Keyword(s):  
Gas Turbine ◽  
Equivalence Ratio ◽  
Nox Emissions ◽  
Simulation Tool ◽  
Trade Off ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Pulsed Detonation ◽  
Detonation Combustion ◽  
Aero Engine

In the present paper, the synergistic combination of inter-cooling with pulsed detonation combustion is analyzed concerning its contribution to NOx and CO2 emissions. CO2 is directly proportional to fuel burn and can, therefore, be reduced by improving specific fuel consumption and reducing engine weight and nacelle drag. A model predicting NOx generation per unit of fuel for pulsed detonation combustors, operating with jet-A fuel, is developed and integrated within Chalmers University’s gas turbine simulation tool GESTPAN. The model is constructed using CFD data obtained for different combustor inlet pressure, temperature and equivalence ratio levels. The NOx model supports the quantification of the trade-off between CO2 and NOx emissions in a 2050 geared turbofan architecture incorporating intercooling and pulsed detonation combustion and operating at pressures and temperatures of interest in gas turbine technology for aero-engine civil applications.

First and Second Law Analysis of Intercooled Turbofan Engine

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Xin Zhao ◽  
Oskar Thulin ◽  
Tomas Grönstedt
Keyword(s):  
High Pressure ◽  
Conceptual Design ◽  
Exergy Analysis ◽  
Second Law ◽  
Turbofan Engine ◽  
Blade Height ◽  
Turbofan Engines ◽  
Fuel Burn ◽  
Aero Engine ◽  
Last Stage

Although the benefits of intercooling for aero-engine applications have been realized and discussed in many publications, quantitative details are still relatively limited. In order to strengthen the understanding of aero-engine intercooling, detailed performance data on optimized intercooled (IC) turbofan engines are provided. Analysis is conducted using an exergy breakdown, i.e., quantifying the losses into a common currency by applying a combined use of the first and second law of thermodynamics. Optimal IC geared turbofan engines for a long range mission are established with computational fluid dynamics (CFD) based two-pass cross flow tubular intercooler correlations. By means of a separate variable nozzle, the amount of intercooler coolant air can be optimized to different flight conditions. Exergy analysis is used to assess how irreversibility is varying over the flight mission, allowing for a more clear explanation and interpretation of the benefits. The optimal IC geared turbofan engine provides a 4.5% fuel burn benefit over a non-IC geared reference engine. The optimum is constrained by the last stage compressor blade height. To further explore the potential of intercooling the constraint limiting the axial compressor last stage blade height is relaxed by introducing an axial radial high pressure compressor (HPC). The axial–radial high pressure ratio (PR) configuration allows for an ultrahigh overall PR (OPR). With an optimal top-of-climb (TOC) OPR of 140, the configuration provides a 5.3% fuel burn benefit over the geared reference engine. The irreversibilities of the intercooler are broken down into its components to analyze the difference between the ultrahigh OPR axial–radial configuration and the purely axial configuration. An intercooler conceptual design method is used to predict pressure loss heat transfer and weight for the different OPRs. Exergy analysis combined with results from the intercooler and engine conceptual design are used to support the conclusion that the optimal PR split exponent stays relatively independent of the overall engine PR.

Thermodynamics Cycle Analysis, Pressure Loss and Heat Transfer Assessment of a Recuperative System for Aero Engines

2014 ◽  
Author(s):  
A. Goulas ◽  
S. Donnerhack ◽  
M. Flouros ◽  
D. Misirlis ◽  
Z. Vlahostergios ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Fuel Consumption ◽  
Heat Exchangers ◽  
Engine Performance ◽  
Specific Fuel Consumption ◽  
Hot Gas ◽  
Research Activities ◽  
Aero Engine ◽  
Overall Efficiency ◽  
Aero Engines

Aiming in the direction of designing more efficient aero engines, various concepts have been developed in recent years, among which is the concept of an intercooled and recuperative aero engine. Particularly in the area of recuperation, MTU Aero Engines has been driving research activities in the last decade. This concept is based on the use of a system of heat exchangers mounted inside the hot-gas exhaust nozzle (recuperator). Through the operation of the system of heat exchangers, the heat from the exhaust gas, downstream the LP turbine of the jet engine is driven back to the combustion chamber. Thus, the preheated air enters the engine combustion chamber with increased enthalpy, providing improved combustion and by consequence, increased fuel economy and low-level emissions. If additionally an intercooler is placed between the compressor stages of the aero engine, the compressed air is then cooled by the intercooler thus, less compression work is required to reach the compressor target pressure. In this paper an overall assessment of the system is presented with particular focus on the recuperative system and the heat exchangers mounted into the aero engine’s exhaust nozzle. The herein presented results were based on the combined use of CFD computations, experimental measurements and thermodynamic cycle analysis. They focus on the effects of total pressure losses and heat exchanger efficiency on the aero engine performance especially the engine’s overall efficiency and the specific fuel consumption. More specifically, two different hot-gas exhaust nozzle configurations incorporating modifications in the system of heat exchangers are examined. The results show that significant improvements can be achieved in overall efficiency and specific fuel consumption hence contributing into the reduction of CO2 and NOx emissions. The design of a more sophisticated recuperation system can lead to further improvements in the aero engine efficiency in the reduction of fuel consumption. This work is part of the European funded research program LEMCOTEC (Low Emissions Core engine Technologies).

scholarly journals Improving the efficiency of aviation turbofan engines by using an intercooler and a recuperative heat exchanger

2020 ◽  
Vol 19 (3) ◽  
pp. 85-99
Author(s):  
H. Omar ◽  
V. S. Kuz'michev ◽  
A. Yu. Tkachenko
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Fuel Efficiency ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Working Process ◽  
Thermodynamic Cycles ◽  
Turbofan Engines ◽  
Aircraft System ◽  
Recuperative Heat Exchanger

Continuous improvement of fuel efficiency of aircraft engines is the main global trend in modern engine construction. To date, aviation gas turbine engines have reached a high degree of thermodynamic and design-and technology perfection. One of the promising ways to further improve their fuel efficiency is the use of complex thermodynamic cycles with turbine exhaust heat regeneration and with intermediate cooling in the process of air compression. Until recently, the use of cycles with a recuperative heat exchanger and an intercooler in aircraft gas turbine engines was restrained by a significant increase in the mass of the power plant due to the installation of heat exchangers. Currently, it has become technologically possible to create compact, light, high-efficiency heat exchangers for use on aircraft without compromising their performance. An important target in the design of engines with heat recovery is to select the parameters of the working process that provide maximum efficiency of the aircraft system. The article focuses on the statement of the task of optimization and choice of rational parameters of the working process of a bypass three-shaft turbojet engine with an intercooler and a recuperative heat exchanger. On the basis of the developed method multi-criteria optimization was carried out by means of numerical simulations. The results of optimization of thermodynamic cycle parameters of a bypass three-shaft turbojet engine with an intercooler and a recuperative heat exchanger in the aircraft system according to such criteria as the total weight of the engine and fuel required for the flight, and the aircraft specific fuel consumption per ton - kilometer of the payload are presented. A passenger aircraft of the Airbus A310-300 type was selected. The developed mathematical model for calculating the mass of a compact heat exchanger, designed to solve optimization problems at the stage of conceptual design of the engine is presented. The developed methods and models are implemented in the ASTRA program. The possibility of improving the efficiency of turbofan engines due to the use of complex thermodynamic cycles is shown.

Aero Engine Concepts Beyond 2030: Part 1 - the Steam Injecting and Recovering Aero Engine

2020 ◽  
Author(s):  
Oliver Schmitz ◽  
Hermann Klingels ◽  
Petra Kufner
Keyword(s):  
Specific Power ◽  
Thermodynamic Efficiency ◽  
Nox Formation ◽  
Noticeable Increase ◽  
Fuel Burn ◽  
Exhaust Heat ◽  
Aero Engine ◽  
Technology Level ◽  
The Impact ◽  
Engine Concept

Abstract Recognizing the attention currently devoted to the environmental impact of aviation, this three-part publication series introduces two new aircraft propulsion concepts for the timeframe beyond 2030. This first part focuses on the steam injecting and recovering aero engine concept. Exhaust heat generated steam is injected into the combustion chamber. By use of a condenser, installed behind the steam generator, the water is recovered from the exhaust gas-steam mixture. Both lead to a noticeable increase in specific power compared to a conventional gas turbine and, foremost, to a significant increase in thermodynamic efficiency. The proposed concept is expected to reduce fuel burn and CO2 emissions by about 15 % and NOx formation can be almost completely avoided compared to state-of-the-art engines of the same technology level. Moreover, the described concept has the potential to drastically reduce or even avoid the formation of condensation trails. Thus, the steam injecting and recovering aero engine concept operated with sustainable aviation fuels offers the potential for climate-neutral aviation. Based on consistent thermodynamic descriptions, preliminary designs and initial performance studies, the potentials of the concepts are analyzed. Complementarily, a detailed discussion on concrete engineering solutions considers the implementation into aircraft. Finally, the impact on emissions is outlined.

Applying heat pipes to a novel concept aero engine: Part 2 – Design of a heat-pipe heat exchanger for an intercooled-recuperated aero engine

2011 ◽  
Vol 115 (1169) ◽  
pp. 403-410
Author(s):  
R. Camilleri ◽  
S. Ogaji ◽  
P. Pilidis
Keyword(s):  
Heat Exchanger ◽  
Heat Pipe ◽  
Gas Turbine ◽  
Heat Exchangers ◽  
Heat Pipes ◽  
Advisory Council ◽  
Pressure Losses ◽  
Aero Engine ◽  
Cold Pressure ◽  
Pipe Heat

Abstract With the ever-increasing pressure for cleaner and more fuel efficient aero engines, gas turbine manufacturers are faced with a big challenge which they are bound to accept and act upon. The path from current high bypass ratio (BPR) engines to ultra high BPR engines via geared turbo fans will enable a significant reduction in SFC and CO2 emissions. However, in order to reach the emission levels set by the advisory council for aeronautics research in Europe (ACARE), the introduction of more complex cycles that can operate at higher thermal efficiencies is required. Studies have shown that one possibility of achieving higher core efficiencies and hence lower SFC is through the use of an intercooled recuperated (ICR) core. The concept engine, expected to enter into service around 2020, will make use of a conventional fin plate heat exchangers (HEX) for the intercooler and a tube type HEX as the recuperator. Although the introduction of these two components promises a significant reduction in SFC levels, they will give also rise to higher engine complexity, pressure losses and additional weight. Thus, the performance of the engine relies not only on the behaviour of the usual gas turbine components, but will be heavily dependent on the two heat exchangers. This paper seeks to introduce a heat pipe heat exchanger (HPHEX) as alternative designs for the intercooler and the recuperator. The proposed HPHEX designs for application in an ICR aero engine take advantage of the convenience of the geometry of miniature heat pipes to provide a reduction in pressure losses and weight when compared to conventional HEX. The proposed HPHEX intercooler design eliminates any ducting to and from the intercooler, offering up to 32% reduction in hot pressure losses, 34% reduction in cold pressure losses and over 41% reduction in intercooler weight. On the other hand the proposed HPHEX recuperator design can offer 6% improvement in performance, while offering 36% reduction in cold pressure losses, up to 80% reduction in hot pressure losses and over 31% reduction in weight. An ICR using HPHEX for the intercooler and recueprator may offer up to 2·5% increase in net thrust, while still offering 3% reduction in SFC and up to 7·7% reduction in NOX severity parameter, when compared to the ICR using conventional HEX.

Best Strategies for the Development of a Holistic Porosity Model of a Heat Exchanger for Aero Engine Applications

2015 ◽  
Author(s):  
K. Yakinthos ◽  
D. Misirlis ◽  
Z. Vlahostergios ◽  
M. Flouros ◽  
S. Donnerhack ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Pressure Loss ◽  
Engine Performance ◽  
Operational Parameters ◽  
Tubular Heat Exchanger ◽  
Tube Heat Exchanger ◽  
Aero Engine ◽  
Porosity Model

In an attempt to manage CFD computations in aero engine heat exchanger design, this work presents the best strategies and the methodology used to develop a holistic porosity model, describing the heat transfer and pressure drop behavior of a complex profiled tubular heat exchanger for aero engine applications. Due to the complexity of the profile tube heat exchanger geometry and the very large number of tubes, detailed CFD computations require very high CPU and memory resources. For this reason the complex heat exchanger geometry is replaced in the CFD computations by a simpler porous medium geometry with predefined pressure loss and heat transfer. The present work presents a strategy for developing a holistic porosity model adapted for heat exchangers, which is capable to describe their macroscopic heat transfer and pressure loss average performance. For the derivation of the appropriate pressure loss and heat transfer correlations, CFD computations and experimental measurements are combined. The developed porosity model is taking into consideration both streams of the heat exchanger (hot and cold side) in order to accurately calculate the inner and outer pressure losses, in relation to the achieved heat transfer and in conjunction with the selected heat exchanger geometry, weight and operational parameters. For the same heat exchanger, RAM and CPU requirement reductions were demonstrated for a characteristic flow passage of the heat exchanger, as the porosity model required more than 80 times less computational points than the detailed CFD model. The proposed porosity model can be adapted for recuperation systems with varying heat exchanger designs having different core arrangements and tubes sizes and configurations, providing an efficient tool for the optimization of the heat exchangers design and leading to an increase of the overall aero engine performance.

Multi-Objective Optimization of a Regenerative Rotorcraft Powerplant: Quantification of Fuel Economy and Environmental Impact

2015 ◽  
Author(s):  
Fakhre Ali ◽  
Konstantinos Tzanidakis ◽  
Ioannis Goulos ◽  
Vassilios Pachidis ◽  
Roberto d’Ippolito
Keyword(s):  
Heat Exchanger ◽  
Environmental Impact ◽  
Fuel Economy ◽  
Pareto Front ◽  
Pressure Ratio ◽  
Nox Emissions ◽  
Fuel Burn ◽  
Engine Design ◽  
Compressor Pressure Ratio ◽  
Pressure Compressor

A computationally efficient and cost effective simulation framework has been proposed to perform a multidisciplinary design and optimization of a conceptual regenerative rotorcraft powerplant configuration at mission level. A generic rotorcraft model, representative of a modern twin-engine light civil rotorcraft has been investigated, operating under a representative passenger air taxi mission. The design space corresponding to the conceptual regenerative engine thermodynamic cycle parameters as well as engine and mission design outputs in terms of low pressure compressor pressure ratio, high pressure compressor pressure ratio, turbine entry temperature, mass flow, heat exchanger effectiveness, engine design point specific fuel consumption, engine weight, mission fuel burn and mission CO2 and NOx emissions has been thoroughly investigated through the application of a latin hypercube sampling, design of experiment approach. The interdependencies between the various engine design inputs/outputs are quantified by establishing the corresponding linear correlations between the aforementioned engine inputs/outputs as well as for the corresponding mission output parameters. A multi-objective Particle Swarm Optimizer is employed to derive Pareto front models quantifying the optimum interrelationship between the mission fuel burn and NOx emissions inventory. The acquired engine cycle design parameters corresponding to the span of the Pareto front suggest that the heat exchanger design effectiveness is the key design parameter representing the interdependency between engine fuel economy and environmental impact. The acquired optimum engine models, obtained from the Pareto front, are subsequently deployed for the design of conceptual rotorcraft engine configurations, targeting improved mission fuel economy, enhanced payload-range capability and overall environmental impact.

Aero Engine Concepts Beyond 2030: Part 1 — The Steam Injecting and Recovering Aero Engine

2020 ◽  
Author(s):  
Oliver Schmitz ◽  
Hermann Klingels ◽  
Petra Kufner
Keyword(s):  
Specific Power ◽  
Thermodynamic Efficiency ◽  
Nox Formation ◽  
Noticeable Increase ◽  
Fuel Burn ◽  
Exhaust Heat ◽  
Aero Engine ◽  
Readiness Level ◽  
The Impact ◽  
Engine Concept

Abstract Recognizing the attention currently devoted to the environmental impact of aviation, this three-part publication series introduces two new aircraft propulsion concepts for the timeframe beyond 2030. This first part focuses on the steam injecting and recovering aero engine concept. In the second part, the free-piston Composite cycle engine concept is presented. A third publication, building upon those two concepts, presents the project which aims for demonstrating the proof of concept with numerical simulation and test-bench experiments up to a technology readiness level of three. In the steam injecting and recovering aero engine concept, exhaust heat generated steam is injected into the combustion chamber. The humidified mass flow contains significantly more extractable energy than air. Furthermore, the pumping of liquid water up to the necessary pressure requires a magnitude less power than the compression of air, which reduces the internal power demand. Both lead to a noticeable increase in specific power compared to a conventional gas turbine and, foremost, to a significant increase in thermodynamic efficiency. By use of a condenser, installed behind the steam generator, the water is recovered from the exhaust gas-steam mixture. The proposed concept is expected to reduce fuel burn and CO2 emissions by about 15 % and NOx formation can be almost completely avoided compared to state-of-the-art engines of the same technology level. Moreover, the described concept has the potential to drastically reduce or even avoid the formation of condensation trails. Thus, the steam injecting and recovering aero engine concept operated with sustainable aviation fuels offers the potential for climate-neutral aviation. Based on consistent thermodynamic descriptions, preliminary designs and initial performance studies, the potentials of the concepts are analyzed. Complementarily, a detailed discussion on concrete engineering solutions considers the implementation into aircraft. Finally, the impact on emissions is outlined.

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