Search Results (25)

Due to the limitations of pure electric power endurance, turbo-electric hybrid power systems, which offer a high power-to-weight ratio, present a reliable solution for medium- and large-sized vertical take-off and landing (VTOL) aircraft. Traditional energy management strategies often fail to minimize fuel consumption across the entire flight profile while meeting power demands under varying flight conditions. To address this issue, this paper proposes a deep reinforcement learning (DRL)-based energy management strategy (EMS) specifically designed for turbo-electric hybrid propulsion systems. Firstly, the proposed strategy employs a Prior Knowledge-Guided Deep Reinforcement Learning (PKGDRL) method, which integrates domain-specific knowledge into the Deep Deterministic Policy Gradient (DDPG) algorithm to improve learning efficiency and enhance fuel economy. Then, by narrowing the exploration space, the PKGDRL method accelerates convergence and achieves superior fuel and energy efficiency. Simulation results show that PKGDRL has a strong generalization capability in all operating conditions, with a fuel economy difference of only 1.6% from the offline benchmark of the optimization algorithm, and in addition, the PKG module enables the DRL method to achieve a huge improvement in terms of fuel economy and convergence rate. In particular, the prospect theory (PT) in the PKG module improves fuel economy by 0.81%. Future research will explore the application of PKGDRL in the direction of real-time total power prediction and adaptive energy management under complex operating conditions to enhance the generalization capability of EMS. Full article

Faulty synchronizations of synchronous generators can cause significant detrimental effects, primarily due to a large current and high electromagnetic torque. These effects not only impact the generator but they can also extend to the prime mover and the step-up transformer. Furthermore, such events can trigger disturbances in the power system, potentially leading to system collapse if not promptly cleared. Although the autosynchronizers and synchro-check technologies are well established in the industry, faulty synchronizations, such as those caused by incorrect wiring during maintenance or commissioning operations, can go undetected by these systems. Existing protections do not allow for the detection of faulty synchronizations in a timely manner. This paper presents novel protection methods specifically designed for this issue: one based on instantaneous current value and the other on the instantaneous current-derivative value. These schemes are activated exclusively during the synchronizations process, allowing for faster fault detection compared to existing methods, thereby reducing the duration of harmful electrical and mechanical stresses after a faulty synchronization. The effectiveness of the proposed schemes has been validated through computer simulations of a 362 MVA turbo-generator from a thermal power plant and also through experimental tests on a 5 kVA synchronous generator using a specialized laboratory synchronization test bench, yielding promising results. Full article

For next-generation power systems, particularly aero-gas turbine engines, ultra-light and highly efficient heat exchangers are considered key enabling technologies for realizing advanced cycles. Consequently, the development of efficient and accurate aero-engine heat exchanger test equipment is essential to support future gas turbine heat exchanger advancements. This paper presents the development of a high-pressure and high-temperature (HPHT) heat exchanger test facility designed for aero-engine heat exchangers. The maximum temperature and pressure of the test facility were configured to simulate the conditions of the last-stage compressor of a large civil engine, specifically 1000 K and 5.5 MPa. These conditions were achieved using multiple electric heater systems in conjunction with an air compression system consisting of three turbo compressor units and a reciprocating compressor unit. A commissioning test was conducted using a compact tubular heat exchanger, and the results indicate that the test facility operates stably and that the measured data closely align with the predicted performance of the heat exchanger. A commissioning test of the tubular heat exchanger showed a thermal imbalance of 1.02% between the high-pressure (HP) and low-pressure (LP) lines. This level of imbalance is consistent with the ISO standard uncertainty of ±2.3% for heat dissipation. In addition, CFD simulation results indicated an average deviation of approximately 1.4% in the low-pressure outlet temperature. The close alignment between experimental and CFD results confirms the theoretical reliability of the test bench. The HPHT thermal performance test facility will be expected to serve as a critical test bed for evaluating heat exchangers for current and future gas turbine applications. Full article

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle. Full article

To accurately predict the matching relationships between the various components and the engine performance in the whole aero-engine environment, this study introduces a two-dimensional throughflow simulation method for the whole aero-engine. This method is based on individual throughflow solvers for the turbo-machinery and the combustor. It establishes a throughflow simulation model for the whole engine by integrating with the compressor-turbine co-operating equations and boundary conditions. The turbo-machinery throughflow solver employs a circumferentially averaged form of the time-dependent Navier–Stokes equations (N-S) as the governing equation. The combustor solver uses the Reynolds Average Navier–Stokes (RANS) method to solve flow and chemical reaction processes by constructing turbulence, combustion, and radiation models. The accuracy of the component solver is validated using Pratt and Whitney’s three-stage axial compressor (P&W3S1) and General Electric’s high-pressure turbine (GE-EEE HPT), and the predicted results are consistent with the experimental data. Finally, the developed throughflow method is applied to simulate the throttling characteristics of the WZ-X turboshaft engine. The results predicted by the throughflow program are consistent with the GasTurb calculations, including the trends of shaft power delivered, specific fuel consumption (SFC), inlet airflow, and total pressure ratio of the compressor. The developed method to perform throughflow simulation of the whole aero-engine eliminates the dependence on a general component map. It can quickly obtain the meridian flow field parameters and overall engine characteristics, which is expected to guide the design and modification of the engine in the future. Full article

The H2-ICE project aims at developing, through numerical simulation, a new generation of hybrid powertrains featuring a hydrogen-fueled Internal Combustion Engine (ICE) suitable for 12 m urban buses in order to provide a reliable and cost-effective solution for the abatement of both CO₂ and criteria pollutant emissions. The full exploitation of the potential of such a traction system requires a substantial enhancement of the state of the art since several issues have to be addressed. In particular, the choice of a more suitable fuel injection system and the control of the combustion process are extremely challenging. Firstly, a high-fidelity 3D-CFD model will be exploited to analyze the in-cylinder H2 fuel injection through supersonic flows. Then, after the optimization of the injection and combustion process, a 1D model of the whole engine system will be built and calibrated, allowing the identification of a “sweet spot” in the ultra-lean combustion region, characterized by extremely low NOx emissions and, at the same time, high combustion efficiencies. Moreover, to further enhance the engine efficiency well above 40%, different Waste Heat Recovery (WHR) systems will be carefully scrutinized, including both Organic Rankine Cycle (ORC)-based recovery units as well as electric turbo-compounding. A Selective Catalytic Reduction (SCR) aftertreatment system will be developed to further reduce NOx emissions to near-zero levels. Finally, a dedicated torque-based control strategy for the ICE coupled with the Energy Management Systems (EMSs) of the hybrid powertrain, both optimized by exploiting Vehicle-To-Everything (V2X) connection, allows targeting H2 consumption of 0.1 kg/km. Technologies developed in the H2-ICE project will enhance the know-how necessary to design and build engines and aftertreatment systems for the efficient exploitation of H2 as a fuel, as well as for their integration into hybrid powertrains. Full article

Efficient and low-polluting mobility is a major demand in all countries. Hybrid electric vehicles have already shown to be suitable to respond to this need, being a reliable alternative to conventional cars, at least in urban environments. Nevertheless, such vehicles present a yet unexplored potential. In this paper, we will investigate how the powertrain efficiency may possibly benefit, in an integrated drivetrain for a hybrid electric vehicle, based on a turbocharged gasoline engine, of an innovative supercharging system. The compressor and turbine will be mechanically decoupled so as to independently optimize their operation, avoiding turbo lag and maximizing energy recovery by completely eliminating the waste-gate valve. This, in turns, requires changing the turbine so as to have a flattest possible efficiency/load curve. Therefore, an ad-hoc designed turbine will be implemented in the decoupled configuration, to be used to drive an electrical generator and produce electrical energy for charging the battery. This study presents a preliminary assessment of the potential of a turbo-compounded system for a 1L turbocharged gasoline engine for a small city car. To this aim, a one-dimensional dynamic model of the engine has been built in GT-Suite and has been calibrated and validated by means of experimental data obtained on a dynamometer, both in steady state and dynamic conditions. In particular, the model has been calibrated by means of experimental data obtained in stationary conditions and its robustness has then been verified through experimental data obtained under transient conditions. The model also includes data retrieved from the characterization of the existing turbine and compressor, while a new performance map for the turbine has been designed to better exploit the potential of the components’ decoupling. Results include the estimation of energy recovery potential of such a solution. Under the implementation of a straightforward control strategy, which runs both compressor and turbine at the same speed, the system is able to achieve a 60.57% increase in energy recovered from the exhaust gasses in the turbine. Afterwards, an attempt was made to limit the minimum turbine speed to 45000 rpm and simultaneously decrease the instantaneous speed by 3000 rpm compared to the compressor, attaining a further increase of 1.7% in the energy recovered by the turbine. Full article

Due to the high operating temperature of solid oxide fuel cells (SOFC), the system efficiency depends on efficient thermal integration and the effective construction of system configuration. In this study, nine configurations of system integration design were investigated to evaluate the possible improvement of system efficiency with energy separation devices. The models were developed under the Matlab/Simulink^® platform with Thermolib^® module. The reference layout of the simulation included an SOFC stack, a compressor, an external reformer with a burner, a three-way valve, a heat exchanger, and a water pump. From the reference case, eight cases extended layouts for the capability of thermal energy utilization with a catalytic converter, SOFC hybridization, and an energy separation device. Since the energy separation device was beneficial to thermal energy utilization via a boost to the gas temperature, electric efficiency, and combined heat and power (CHP) efficiency was improved with the thermal integration of the energy separation device with a turbo generator. Full article

The efficiency of hybrid electric vehicles may be substantially increased if the energy of exhaust gases, which do not complete the expansion inside the cylinder of the internal combustion engine, is efficiently recovered using a properly designed turbo-generator and employed for vehicle propulsion. Previous studies, carried out by the same authors of this work, showed a potential hybrid vehicle fuel efficiency increment up to 15% employing a 20 kW turbine on a 100 HP-rated power thermal unit. The innovative thermal unit proposed here is composed of a supercharged engine endowed with a properly designed turbo-generator, which comprises two fundamental elements: an exhaust gas turbine expressly designed and optimized for the application, and a suitable electric generator necessary to convert the recovered energy into electric energy, which can be stored in the on-board energy storage system of the vehicle. In this two-part work, the realistic efficiency of the innovative thermal unit for hybrid vehicles is evaluated and compared to a traditional turbocharged engine. In Part 1, the authors presented a model for the prediction of the efficiency of a dedicated radial turbine, based on a simple but effective mean-line approach; the same paper also reports a design algorithm, which, thanks to some assumptions and approximations, allows fast determination of the right turbine geometry for a given design operating condition. It is worth pointing out that, being optimized for quasi-steady power production, the exhaust gas turbine here considered is quite different from the ones commonly employed for turbocharging applications; for this reason, and in consideration of the required power size, such a turbine is not available on the market, nor has its development been previously carried out in the scientific literature. In this paper, Part 2, a radial turbine geometry is defined for the thermal unit previously calculated, employing the design algorithm described in Part 1; the realistic energetic advantages that could be achieved by the implementation of the turbo-generator on a hybrid propulsion system are evaluated through the performance prediction model under different operating conditions of the thermal unit. As an overall result, it was estimated that, compared to a reference traditional turbocharged engine, the turbo-compound system could gain vehicle efficiency improvement between 3.1% and 17.9%, according to the output power delivered, with an average efficiency increment of 10.9% evaluated on the whole operating range. Full article

Life without mobility is inconceivable. To enable this connectivity, one must find a way to progress towards a more sustainable transportation. In the aviation industry, a comprehensive understanding of greening technologies such as electrification of the propulsion system for commercial aircraft is required. A hybrid-electric propulsion concept applied to a regional aircraft is studied in the context of the FutPrInt50 project. To this end, the hybrid-electric propulsive system components are modeled, validated, and evaluated using computational and experimental data presented in the literature. The components are then assembled to construct the three powertrains for the hybrid-electric propulsion systems (Series, Parallel and Turboelectric) and parametric studies are carried out to study the influence of various battery parameters and hybridization factor. The performance results for a simple mission profile are generated. Together with a thermal management system, multi-objective optimization studies for the different architectures are then performed, with the power hybridization factor as the design variable and minimization of total mass and emissions as objective functions. Full article

Worldwide concerns over energy optimization and harnessing have sparked a variety of research on utilizing wasted energy. Natural gas, in particular, has been an essential energy commodity for domestic and industrial applications. This paper approaches the same principle throughout the Egyptian natural gas conventional national grid. The real case of Egypt’s Al-Alamein city gas line extension is analytically studied for energy harness. Thus, this paper aims to study the replacement of conventional energy-wasting pressure-reducing stations with power-producing expander generator systems to utilize pressure reduction in electricity generation. The mathematical equations that describe the energy recovery processes are presented. Reliable commercial software is used to verify the possible implementation of turbo expander stations in three scenarios. Each scenario is defined, and its main components and numerical parameters are introduced. Hence, the resulting energy outputs and applicability of all scenarios are compared to provide adequate energy recovery solutions. Full article

This paper evaluates the performance and practical challenges associated with fabricating and flight testing an unmanned aircraft powered by a turboelectric system based on a 7 kW turbine engine. Emerging hybrid gas-electric aircraft concepts have been the subject of numerous design studies and analytical evaluations; however, there is a critical need to identify and assess practical issues associated with integrating a hybrid turboelectric power system into an aircraft. The purpose of this study, relevant to emerging hybrid-powered aircraft, is to evaluate and retrofit a prototype turboelectric power system to an existing 391 N gross take-off weight unmanned airframe. The representative 7 kW turboelectric system was installed to identify challenges and to formulate data-driven recommendations for general application to urban air mobility. This work addresses performance, power and thermal management, vibration, and acoustic emissions. Results include a weight breakdown with the turboelectric system making up 21% of the total aircraft weight, in-flight voltage and current measurements with maximum loads observed during a dive pull-out, temperature measurements, accelerometer measurements, and far field sound pressure level measurements. Practical recommendations from this study are applicable to power system reliability, electronic component selection, cooling requirements, and peak power behavior, informing the design of future hybrid gas–electric aircraft. Full article

As is widely known, internal combustion engines are not able to complete the expansion process of the gas inside the cylinder, causing theoretical energy losses in the order of 20%. Several systems and methods have been proposed and implemented to recover the unexpanded gas energy, such as turbocharging, which partially exploits this energy to compress the fresh intake charge, or turbo-mechanical and turbo-electrical compounding, where the amount of unexpanded gas energy not used by the compressor is dedicated to propulsion or is transformed into electric energy. In all of these cases, however, maximum efficiency improvements between 4% and 9% have been achieved. In this work, the authors deal with an alternative propulsion system composed of a CNG-fueled spark ignition engine equipped with a turbine-generator specifically dedicated to unexpanded exhaust gas energy recovery and with a separated electrically driven turbocompressor. The system was conceived specifically for hybrid propulsion architectures, with the electric energy produced by the turbine generator being easily storable in the on-board energy storage system and re-usable for vehicle traction. The proposed separated electric turbo-compound system has not been studied in the scientific literature, nor have its benefits ever been analyzed. In this paper, the performances of the analyzed turbo-compound system are evaluated and compared with a traditional reference turbocharged engine from a hybrid application perspective. It is demonstrated that separated electric compounding has great potential, with promising overall efficiency advantages: fuel consumption reductions of up to 15% are estimated for the same power output level. Full article

Research in the process of internal combustion engines shows that their efficiency can be increased through several technical and functional solutions. One of these is turbocharging. For certain engine operating modes, the available energy of the turbine can also be used to drive an electricity generator. The purpose of this paper is to highlight the possibilities and limitations of this solution. For this purpose, several investigations were carried out in the virtual environment with the AMESim program, as well as experimental research on a diesel engine for automobiles and on a stand for testing turbochargers (Turbo Test Pro produced by CIMAT). The article also includes a comparative study between the power and torque of the naturally aspirated internal combustion engine and equipped with a hybrid turbocharger. The results showed that the turbocharger has a very high operating potential and can be coupled with a generator without decreasing the efficiency of the turbocharger or the internal combustion engine. The main result was the generation of electrical power of 115 W at a turbocharger shaft speed of 140,000–160,000 rpm with an electric generator shaft speed of 14,000–16,000 rpm. There are many constructive solutions for electrical turbochargers with the generator positioned between the compressor and the turbine wheel. This paper is presenting a solution of a hybrid turbocharger with the generator positioned and coupled with the compressor wheel on the exterior side. Full article

Taking a 1000 MW turbine generator as the research object, the short-circuit fault in electrical disturbance is analyzed. Since it is very difficult to carry out fault analysis experiments and research on actual systems, simulation analysis is one of the more effective means of electrical fault diagnosis; the simulation’s results approach the actual behavior of the system and are ideal tools for power system analysis, and can provide an empirical basis for practical applications. The short-circuit fault model of the SIMULINK power system is built to analyze the two types of faults of generator terminals short-circuit and power grid short-circuit. The impact load spectrum, fault current and speed fluctuation between low-voltage rotors were extracted and analyzed. The conclusion is that the impact value of electromagnetic torque at the generator terminal is greater than that on the power grid side. The impact value of a two-phase short-circuit at the generator terminal is the largest, and that of a three-phase short-circuit on the power grid side is the smallest. The transient impulse current of a three-phase short-circuit at any fault point is greater than that of a two-phase short-circuit; the impulse current of the grid side short-circuit is much greater than that of the generator terminal short-circuit; the speed fluctuation and fluctuation difference caused by the three-phase short-circuit in the grid side are the largest. The alternating frequency of the transient electromagnetic force of the four kinds of faults avoids the natural frequency of the torsional vibration of the shaft system, and the torsional resonance of the shaft system in the time domain of the short-circuit fault will not appear. However, after the fault is removed, the residual small fluctuation torque in the system has a potential impact on the rotor system. This research shows an analysis of the structural integrity and safe operation of turbine generator units after a short-circuit fault, which can not only be applied to engineering practice, but also provide a theoretical basis for subsequent research. Full article