Hybrid Propulsion System Research Articles

A simplified automated approach for a preliminary safety assessment of distributed electric and hybrid propulsion systems

AbstractTo reduce the environmental impact of future aircraft, the usage of disruptive hybrid electric propulsion systems, in conjunction with distributed propulsion systems, is envisioned. The complexity of those novel powertrain concepts increases significantly. Besides nominal system characteristics, this particularly applies for off-nominal behaviour and consequences. As the safety impact on aircraft level is not always obvious, the suitability of a given component failure rate has to be analysed already in a preliminary design stage. Within this work, a method shall be introduced that allows a simplified automated safety assessment of any powertrain architecture. All relevant combinations of single and multiple failures are identified and a combined failure rate is derived. Thereafter, the impact of single and multiple component failures is evaluated on aircraft level. A selection of metrics for top-level-aircraft functions is used to implement an impact-driven analysis for each relevant failure case. The metrics used assess the adverse effects on climb performance, lateral controllability and range degradation. For all failure combinations, these effects can be validated against requirements imposed on the configuration. The possibility to formulate failure rate-related requirements follows the idea to target an equivalent level of safety compared to existing regulations, independently of the nature of the failure scenario. Results of this study show the necessity for a reevaluation of the configurations assessed, either regarding their architecture or the assumed component failure rate. The method allows an early detection of configuration-specific shortcomings of complex powertrain architectures already in a preliminary aircraft design stage.

Novel Nuclear Power and Fossil Fuel Hybrid Propulsion Systems for Long-Endurance Unmanned Aerial Vehicles: Configuration Comparison and Performance Optimization

Aircraft nuclear propulsion system can significantly enhance the endurance, but its large size and weight become disadvantages against the conventional fossil fuel propulsion system. In this paper, a novel nuclear power and fossil fuel hybrid propulsion system, which combines the lithium-cooled fast reactor and the kerosene-fueled turbine engine, is proposed to meet the power requirements of different flight segments. Performance assessment and comparison among different hybrid configurations is performed. Results indicate that the configuration combining the nuclear power module with a high bypass ratio turbofan engine is the most promising for aircraft. The primary optimization shows that there is a trade-off between the weight of the nuclear power module and the specific thrust, and the optimal weight of nuclear power module is 3942 kg, with the specific thrust of 195.8 N·kg-1·s-1. The aircraft equipped with the hybrid propulsion system operates at the maximum altitude of approximately 18.2 km and reaches a maximum Mach number of 0.71, allowing for sustained flight for several months in cruise segment. The turbofan engine, nuclear reactor, ancillary systems, shield, and heat exchanger account for 11%, 23%, 11%, 17% and 1% of the fuel mass of the original unmodified aircraft.

Empirical Evaluation of the Replacement of Conventionally Powered Vehicles with Hybrid and Electric Vehicles on the Example of the Poznań Agglomeration

From the collected data of the Central Register of Vehicles, an average of 15,000 vehicles were registered per month in the Greater Poland region in 2020–2022. It should be borne in mind that most of them were conventionally powered cars-spark-ignition or compression-ignition engines, the daily operation of which negatively affects the environment. Institutions responsible for regulating the homologation of passenger vehicles are introducing increasingly stringent emission standards to reduce the harmful effects of vehicles on the environment. In addition, more and more public campaigns are being conducted on the use of cars equipped with alternative propulsion systems, e.g., electric, full-hybrid or increasingly popular hydrogen-powered vehicles. The publication presents forecasts for the replacement of vehicles equipped with spark-ignition and compression-ignition engines with cars equipped with hybrid propulsion systems or electric systems. Tests of vehicles in real operating conditions were carried out in the Poznań agglomeration in an urban area, where the number of vehicles per area is higher than in the case of a nonurban zone. The research objects were both cars equipped with a conventional drivetrain and a hybrid system. The research made it possible to draw up a hybridization index, which was then applied to the number of vehicles registered over the past few years.

Performance Evaluation of Hybrid Propulsion System on Fast Patrol Boat

This paper presents a performance evaluation of a hybrid propulsion system applied to a fast patrol boat. The study aims to analyze the efficiency, fuel consumption, and overall operational effectiveness of the hybrid system compared to conventional propulsion methods. A combination of electric motors and diesel engines is utilized in the hybrid setup, allowing for optimized energy use in varying operational conditions. The performance of the system was evaluated through simulation and sea trials, focusing on key metrics such as speed, endurance, maneuverability, and emission reduction. Results indicate that the hybrid system offers significant advantages in terms of fuel savings and reduced environmental impact, particularly during low-speed or patrol operations. This research provides valuable insights into the practical benefits and challenges of implementing hybrid propulsion systems in maritime security operations.

Optimization for fuel consumption and TCO of a heavy-duty truck with electricity-propelled trailer

As renewable energy grows in the heavy-duty truck sector, exploration of diverse solutions with varied energy types and powertrain configurations becomes a necessity. While most studies focus on powertrain configurations in tractors, this study takes a different approach: propose and evaluate new plug-in hybrid configurations with multiple power sources for heavy-duty trucks. The tractor retains its engine powertrain, while the trailer is equipped with electric axle(s), forming a fuel-electricity hybrid propulsion system. The specifications of the electric propulsion system are optimized, using a multi-objective particle swarm optimization algorithm and dynamic programming control algorithm to evaluate the energy consumption and total cost of ownership (TCO). The results highlight the potential of the configuration with three electric axles and single reduction gear in regard to vehicle energy consumption. Conversely, the configuration with one electric axle and a two-speed transmission exhibits the lowest TCO. Under the China World Transient Vehicle Cycle, the fuel consumption of the diesel truck is reduced by up to 44.59 % with the use of the optimized hybrid configuration. The truck's TCO can be then reduced by up to 832 thousand CNY in one-million-kilometer operation. For an actual road operation, these figures change to 34.79 % and 284 thousand CNY, respectively.

Assessing the Impact of Hybrid Propulsion Systems on the Range and Efficiency of Aircraft

The demand for aviation continues to grow, posing issues in terms of fuel consumption, environmental effect, and operational efficiency. In addition, the COVID-19 pandemic has also highlighted the need for sustainable solutions in the aviation sector. To address these issues, hybrid electric propulsion systems have emerged as a potential option. Hybrid electric propulsion systems have the potential to improve airplane performance while reducing environmental impact. This article looks into the effects of hybrid electric propulsion technologies on optimal aircraft range. The study looks at aviation's environmental impact, several hybrid aircraft prototypes, and battery capacity and density challenges. Fuel usage increases in proportion to the weight of the aircraft. As a result, the range is shorter. In modern technology, along with to the added weight of batteries used as energy storage in hybrid propulsion systems, there are low battery densities and capacities. When the researches were reviewed, it was discovered that overcoming these limitations was easier for small aircraft and more difficult for large aircraft. As a consequence of the studies and research conducted, the development of light and reliable batteries with high energy density and capacity would expand the range of hybrid aircraft and allow them to be used more efficiently over long distances.

Fuzzy Logic-Based Energy Management Strategy for Hybrid Fuel Cell Electric Ship Power and Propulsion System

The growing use of proton-exchange membrane fuel cells (PEMFCs) in hybrid propulsion systems is aimed at replacing traditional internal combustion engines and reducing greenhouse gas emissions. Effective power distribution between the fuel cell and the energy storage system (ESS) is crucial and has led to a growing emphasis on developing energy management systems (EMSs) to efficiently implement this integration. To address this goal, this study examines the performance of a fuzzy logic rule-based strategy for a hybrid fuel cell propulsion system in a small hydrogen-powered passenger vessel. The primary objective is to optimize fuel efficiency, with particular attention on reducing hydrogen consumption. The analysis is carried out under typical operating conditions encountered during a river trip. Comparisons between the proposed strategy with other approaches—control based, optimization based, and deterministic rule based—are conducted to verify the effectiveness of the proposed strategy. Simulation results indicated that the EMS based on fuzzy logic mechanisms was the most successful in reducing fuel consumption. The superior performance of this method stems from its ability to adaptively manage power distribution between the fuel cell and energy storage systems.

Design and Simulation of eVTOL Aircraft Thermal Management System

Abstract Vertical Take-off and Landing (VTOL) aircraft with hybrid or fully-electric propulsion systems are becoming popular for Urban Air Mobility (UAM) applications. However, they face challenges such as limited power and energy density, stringent operating temperature constraints, and the generation of low-grade waste heat. These issues emphasize the need for effective Thermal Management Systems (TMS) design. In light of the above, this paper aims to design the TMS for a parallel hybrid electric XV-15 aircraft, a widely known civil tiltrotor concept. The TMS is integrated into the aircraft system to assess its impact on energy efficiency and emissions at both aircraft and mission levels. This study considers current state of the art technology and expected advancements over the next two decades to identify the benefits of electrification. In the designed TMS, liquid cooling cold plates serve as the main heat acquisition and cooling system for each electric component. An air-coolant heat exchanger is also incorporated to dissipate the accumulated heat load. The study conducts a comparative analysis to determine the optimal TMS design point. It involves a comparison between two design scenarios: one focused on the cruise condition, which constitutes a significant portion of the flight mission, and another designed specifically for peak heat load conditions. This ensures a holistic evaluation of the TMS's performance across various flight phases, balancing efficiency and resilience to peak demands. Finally, the energy efficiency and emission penalty associated with the TMS integration are quantified and discussed in the study.

Thrust Model and Trajectory Design of an Interplanetary CubeSat with a Hybrid Propulsion System

This paper analyzes the performance of an interplanetary CubeSat equipped with a hybrid propulsion system (HPS), which combines two different types of thrusters in the same deep space vehicle, in a heliocentric transfer between two assigned (Keplerian) orbits. More precisely, the propulsion system of the CubeSat considered in this work consists of a combination of a (low-performance) photonic solar sail and a more conventional solar electric thruster. In particular, the characteristics of the solar electric thruster are modeled using a recent mathematical approach that describes the performance of the miniaturized engine that will be installed on board the proposed ESA’s M-ARGO CubeSat. The latter will hopefully be the first interplanetary CubeSat to complete a heliocentric transfer towards a near-Earth asteroid using its own propulsion system. In order to simplify the design of the CubeSat attitude control subsystem, we assume that the orientation of the photonic solar sail is kept Sun-facing, i.e., the sail reference plane is perpendicular to the Sun-CubeSat line. That specific condition can be obtained, passively, by using an appropriate design of the shape of the sail reflective surface. The performance of an HPS-based CubeSat is analyzed by optimizing the transfer trajectory in a three-dimensional heliocentric transfer between two closed orbits of given characteristics. In particular, the CubeSat transfer towards the near-Earth asteroid 99942 Apophis is studied in detail.

Performance analysis method on the ship with waterjet-propeller hybrid propulsion system: A case study in model scale

The waterjet-propeller hybrid propulsion (WPHP) system shows remarkable potential for comprehensive performance enhancement in a wide speed range. As it consists of two types of significantly different marine propulsors, its performance analysis faces challenges. This paper first illustrates the performance analysis method on a ship model with WPHP system, where the momentum flux method is adopted for the analysis on waterjet subsystem while the classical propulsion theory is used for the propeller subsystem. The proposed method enables detailed investigations on overall performance of WPHP-hull system and respective performances of waterjet and propeller, respectively. As for the case studied, its overall propulsion efficiency is 58.77% at ship design speed in model-scale, where the corresponding propulsion efficiencies of waterjet and propeller subsystems are 59.19% and 56%. The waterjet affords 87.39% load of the bare hull resistance and provides 89.40% net thrust to force the self-propelled hull forward. The waterjet performance is less influenced by the flow-field interference between waterjet and propeller. However, the impact of waterjet intake is relatively significant on accelerating the propeller intake, where propulsion efficiency of propeller decreases. Moreover, high resistance increment fraction of the case is a point that should be further improved to enhance overall performance.

Design and Simulation of a Fuel Cell-based Hybrid Underwater Vehicle Propulsion System in Matlab/Simulink

Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs) have many applications in underwater missions. A recurring issue is managing the power source of the vehicle, especially air-independent propulsion sources, such as batteries, accumulators, and fuel cells, to increase diving depth, underwater endurance, and range. The current article proposes the use of both fuel cells and batteries simultaneously. The subject of the study is Pluto Plus ROVs, which are mine sweeping and counter-terrorism underwater vehicles. The considered system is simulated in Matlab/Simulink. The result was a block diagram that simulates a hybrid propulsion system for submersibles in general and serves as the basis for improving the propulsion system for Pluto Plus ROVs.

Energy efficiency research of propulsion system for series-parallel hybridization of amphibious vehicles

The series-parallel hybrid system has attracted much attention from scholars for its effective integration of the power advantages and operating characteristics of different power sources, which is influenced by international emission regulations, energy-saving and emission reduction policies. As such, a series-parallel hybrid powertrain is introduced to the amphibious vehicle, and an innovative powertrain topology architecture is proposed. Meanwhile, the operation mode and energy efficiency characteristics are investigated during the working process. Firstly, the energy flow simulation model of a series-parallel gas-electric hybrid propulsion system is constructed using a modular modeling approach. Secondly, four operating modes, namely mechanical propulsion, electric propulsion, hybrid propulsion and charging mode, were formulated due to the fact that the propulsion system has multiple forms of power sources in the form of natural gas engine and reversible motor. Meanwhile, the energy flow states were investigated under different operating modes. Meanwhile, a comprehensive investigation of the energy efficiency associated with propulsion, storage and start-up energy was conducted for each specific mode. The results of the research indicated that the energy efficiency of the electric propulsion mode can reach up to 35.15 %, which is the gain from the wide operating range of the motor's high efficiency. The hybrid propulsion mode can obtain the highest energy efficiency of 35.88 %, which fully demonstrates the advantages of coordinating and complementing the two power sources, the natural gas engine and the reversible electric motor. This investigation also provides theoretical and empirical support for optimizing energy matching and formulating energy management strategies.

Cooling of 1 MW Electric Motors through Submerged Oil Impinging Jets for Aeronautical Applications

Electrification of aircraft is a very challenging task as the demand for energy and power is high. While the storage and generation of electrical energy are widely studied due to the limited specific energy and specific power of batteries and fuel cells, electric machines (power electronics and motors) which have years of experience in many industrial fields must be improved when applied to aviation: they generally have a high efficiency but the increase in power levels determines significant thermal loads which, unlike internal combustion engines (ICE), cannot be rejected with the exhaust. There is therefore a need for thermal management systems (TMSs) with the main objective of maintaining operating temperatures below the maximum level required by electric machines. Turboprop aircraft, such as the ATR 72 or the Dash 8-Q400, are commonly used for regional transport and are equipped with two gas turbine engines whose combined power is in the order of 4 MW. Electric and hybrid propulsion systems for these aircraft are being studied by several leading commercial aviation industries and start-ups, and the 1MW motor size seems to be the main option as it could be used in different aircraft configurations, particularly those that exploit distributed electric propulsion. With reference to the topics mentioned above, the present work presents the design of a TMS for a high-power motor/generator whose electrical architecture is known. Once integrated with the electrical part, the TMS must allow a weight/power ratio of 14 kW/kg (or 20 kW/kg at peak power) while maintaining the temperature below the limit temperature with reasonable safety margins. Submerged jet oil is the cooling technique here applied with a focus on diathermic oil. Parameters affecting cooling, like rotor speed and filling factor, are analysed with advanced CFD.

Method of first-approximation calculation of take-off weight of a light aircraft with a hybrid propulsion system

The article discusses a method for calculating, as a first approximation, the take-off weight of a light aircraft with a hybrid power plant based on piston and electric engines. A brief overview of organizations dealing with hybrid power plants is given. The influence of the degree of hybridization of the power plant on the take-off weight of the aircraft is shown. The degree of hybridization of a power plant is understood as a relative value characterizing the distribution of the total power of all engines installed on the aircraft between piston and electric engines. The main parameters necessary to determine the take-off weight of an aircraft to a first approximation are presented. The take-off weight of the aircraft is determined to a first approximation from the equation of its existence. Statistical data of aircraft with different types of power plants are provided on the basis of which calculations are carried out. As a first approximation, the relative mass of the hybrid power plant is determined by analyzing the statistical data of light aircraft with piston and electric engines, from which the corresponding graphs are constructed. After the calculations, conclusions were drawn about the optimal range of characteristics of a light aircraft with a hybrid power plant.

Aircraft electric power plants

The paper presents a review of electrification of the existing propulsion systems and creating new hybrid propulsion systems based on the concept of more electric aircraft and all-electric aircraft in Russia and abroad. New promising directions of electrification of the existing aircraft propulsion systems and creating new hybrid aircraft propulsion systems are specified on the basis of the review.

Investigation on ignition characteristics of charring conductive polymers stimulated by electric energy

The arc ignition based on charring conductive polymers has advantages of simple structure, low ignition power consumption and restart capacity, which bringing it broadly application prospect in hybrid propulsion system of micro/nano satellite. In order to optimize the performance of arc ignition system, it is essential to have a deeper understanding of the ignition processes and ignition characteristics of charring conductive polymers. In this paper, the thermal decomposition, electrical conductivity and thermal conductivity characteristics of charring conductive polymers with different conductive additives and matrix materials were comprehensively evaluated. An experimental investigation was conducted to determine the ignition behaviors and characteristics of different charring conductive polymers in a visual ignition combustor. The experiment result showed that the ignition delay and external energy required for ignition are negatively correlated with voltage and initial temperature of the ignition grain, but positively correlated with oxidizer flow velocity. Compared with charring conductive polymers containing multi-walled carbon nanotube, the ignition delay of charring conductive polymers with carbon black is significantly higher and the pyrolysis time is relatively longer. However, the ignition and initial flame propagation of charring conductive polymers with carbon black is more violent and more inclined to carbon particle ignition. Finally, the restart characteristic of different charring conductive polymers was studied. The ignition delay and external energy required for ignition of different charring conductive polymers all reduced with the increasing of the number of ignitions. However, the ignition characteristics would not change a lot after repeated ignition.

Comparative Analysis of CO2 Emissions, Fuel Consumption, and Fuel Costs of Diesel and Hybrid Dredger Ship Engines

There is a consensus on the need to reduce the emissions of carbon compounds. The increase in global greenhouse gas (GHG) emissions in the maritime industry poses a serious challenge to environmental sustainability, climate change, and the operating costs of ships. This article shows how hybrid versus diesel propulsion technology for ships can help reduce carbon dioxide (CO2) emissions and fuel consumption, and how these changes can be achieved. The need to reduce exhaust emissions and the increasing need for the shipping industry to seek alternative fuels means that existing regulations for marine engines and engine emissions are being updated almost constantly and new regulations are being formulated. The cost implications of the new regulations may lead to an increase in emissions as engines with lower fuel consumption are chosen, i.e., larger marine engines. Alternative approaches are needed to reduce CO2 emissions and fuel consumption, which could ultimately lead to hybrid propulsion for ships. This paper examines the current state of greenhouse gas emissions in shipping by analyzing the CO2 emissions and operating costs of two ships of the same type with similar technical and technological characteristics and different propulsion systems to gain insight into the problem. This paper compares the reductions in CO2 emissions, fuel consumption, and fuel costs for two suction hopper dredgers with standard diesel and hybrid propulsion. The technical characteristics, CO2 emissions, fuel consumption, and price of the two ships were analyzed to determine the advantages and disadvantages of each propulsion system. The novelty of this study is that two suction hopper dredgers from the same company with similar technical–technological characteristics but different propulsion systems were used for the case study and a mathematical procedure for calculating CO2 and other greenhouse gasses was presented in comparison, all to determine to what extent and in what way the hybrid propulsion system of a ship can contribute to reductions in CO2 emissions and fuel costs at the ship and company levels compared to a standard diesel propulsion system. This comparative analysis shows how much lower CO2 emissions, fuel consumption, and fuel cost savings can be expected when using a hybrid propulsion system compared to a standard diesel propulsion system. Finally, a conclusion is drawn on the efficiency and environmental compatibility of the two systems.

Energy storage technologies and their combinational usage in micro/mini unmanned aerial vehicles: a review

As the world population increases, energy consumption extensively increases in every field. Energy is a need in several applications, and depending on its importance, its production should be renewable and clean. In order to meet energy requirements sustainably nowadays various alternative energy resources and improvements are recommended in each sector. One of the environmental steps taken in the aviation industry is the improvement of the propulsion systems and the resources used. For this purpose, the use of electrical energy, a more sustainable option than the energy obtained from fossil fuels, is suggested. In order for electrical energy to be used efficiently, it must be stored. This article reviews energy storage technologies used in aviation, specifically for micro/mini Unmanned Aerial Vehicles (UAVs). Combinational energy storage technologies in hybrid propulsion system architectures and their individual usage in all-electric propulsion system architectures are examined. New-generation propulsion technologies are also evaluated and classified in detail.

Research on hybrid propulsion system with parallel power configuration: theory and experiment based on dynamics

Research on hybrid propulsion system with parallel power configuration: theory and experiment based on dynamics

Navigating legal pathways: Optimizing energy sustainability through compliance, renewable integration, and maritime efficiency

This concept paper explores the intricate interplay between legal frameworks and energy sustainability, focusing on compliance, renewable energy integration, and maritime efficiency. The maritime industry, a significant contributor to global emissions, faces unique challenges and opportunities in transitioning towards sustainability. By examining current legal pathways and best practices, this paper aims to provide insights and recommendations for optimizing energy sustainability in the maritime sector. The concept paper begins by outlining the current regulatory landscape, highlighting key international conventions, regional regulations, and emerging trends shaping the maritime industry's sustainability agenda. It then delves into compliance challenges faced by maritime stakeholders, including regulatory complexities, enforcement issues, and the need for harmonization. The paper also explores the role of renewable energy in maritime sustainability, analyzing successful integration strategies, such as hybrid propulsion systems, wind-assisted propulsion, and shore power solutions. It highlights legal frameworks supporting renewable energy adoption and identifies opportunities for further innovation. Furthermore, the concept paper examines maritime efficiency through legal lenses, discussing measures to improve operational efficiency, reduce emissions, and enhance overall sustainability. It considers the impact of digitalization, automation, and data-driven technologies on maritime operations, emphasizing the need for legal frameworks to adapt to these technological advancements. Based on these analyses, the concept paper proposes recommendations for policymakers, industry stakeholders, and legal practitioners to enhance energy sustainability in the maritime sector. These recommendations include fostering international cooperation, promoting renewable energy investment, and enhancing regulatory clarity and enforcement mechanisms. In conclusion, this concept paper underscores the importance of legal pathways in optimizing energy sustainability in the maritime sector. By embracing compliance, integrating renewable energy, and enhancing efficiency, the maritime industry can transition towards a more sustainable future while navigating the complex legal landscape effectively. Keywords: Energy, Sustainabiltiy, compliance, Policy, Renewable.