Fuel-saving Potential Research Articles

Speed and Route Planning in Evolving Weather for Efficient Voyages

Abstract Fuel-saving potential by optimizing speed as well as route has been studied in a wide variety of operating conditions on a trans-Pacific route. Analysis using different seasonal weather patterns and various ship speeds allows a more robust estimation of possible fuel savings. Up to 18% reduction in fuel consumption was observed on eastbound voyages and up to 13% savings could be obtained on westbound voyages. It was observed that higher energy savings can be obtained for longer voyage times. Because the share of added wave resistance in total resistance is higher for lower speeds and there is greater flexibility to speed up and slow down during the voyage. A detailed comparison between the hindcast and forecast of metocean data has been presented since actual fuel savings would depend on the accuracy of the weather forecast. For future work on operational optimization, it is suggested to use weather forecast data instead of hindcast for realistic estimation of fuel saving potential.

Effect of leaned blades on the aerodynamic performance of contra-rotating open rotor

The contra-rotating open rotor (CROR) engine has gained attention for its outstanding fuel-saving potential. Attention needs to be paid to the propulsion efficiency of the contra-rotating open rotor, as it is the key to realizing the engine’s fuel-saving advantage. In this paper, the performance of CRORs with different lean angles is investigated by numerical simulation. Furthermore, the mechanism of the influence of leaned blades on the propulsion efficiency of the CROR is analyzed. The results show that the positive leaned blades (pressure-surface down) significantly improve the propulsion efficiency of the CROR, with a maximum improvement of 1.34%. In contrast, the negative leaned blades (suction surface down) reduce propulsion efficiency. Due to the radial equilibrium equation, the positive lean increases the radial pressure gradient. The increased gradient enhances flow on the suction surface and reduces the flow reversal region, thus improving the propulsion efficiency. At low advance ratios, the enhanced radial flow due to the leaned blades makes the optimization less effective. By comparing the inlet conditions of the front and rear rotors, it was found that the front rotor was less likely to have a flow reversal region compared to the rear rotor. If a flow reversal region occurs in the channel, it is necessary to introduce leaned blades. The most recommended lean angle is the one that makes the flow reversal region disappear exactly.

Methodology for Evaluating a Distributed Variable-Camber Trailing-Edge System in Preliminary Aircraft Design

A controlled adjustment of the wing camber during cruise flight by an extension of each separate flap allows for wing shape optimization, depending on the current mission point including the prevailing conditions, contributing to an increase in efficiency. This is referred to as variable camber (VC). This paper aims to investigate a methodology for a retrofit application of VC technology with differential flap setting, especially for a segmented trailing-edge system at the overall aircraft level in the preliminary design phase. In addition, an assessment is conducted to clarify whether actuation on the basis of a central shaft system or a decentralized power-by-wire system is advantageous. The investigation is based on a commercial aircraft with a maximum takeoff mass of 270 t and compares the potential of a VC application with an aerostructural twist optimization of the wing. Different configurations of the trailing-edge flaps, ranging from a common two-flap configuration up to a configuration with six trailing-edge devices, are covered in order to give a holistic implementation recommendation, including actuation and flap segmentation. Depending on the reference aircraft, the study shows a considerable fuel-saving potential for VC applications, e.g., 3.5% for the pre-optimized reference on a long-range mission.

Bir yolcu uçağına şekil hafızalı alaşım malzemesi uygulanarak dönüşen kanatçık tasarımının ve etkilerinin araştırılması

Continuous research and development have focused on optimizing wing aerodynamics and reducing fuel consumption in air vehicles since their inception. Winglets, fixed curved structures at wingtips, gained significant attention during the oil crisis for their fuel-saving potential in the aviation industry. This study focuses on designing a morphing winglet using a shape memory alloy (SMA) for improved aerodynamic efficiency and fuel economy under various conditions. The XFLR5 software analyzes the wing's lift and drag ratios at different aircraft stages (take-off, cruise, landing) for different cant angles. Results indicate that a moving winglet enhances the lift/drag ratio and reduces induced drag. Cant angle and angle of attack (AOA) variations play key roles in increasing this ratio. Optimal values for different aircraft stages are determined and discussed alongside existing mechanisms for moving winglets. Experimental data validation from previous studies in the literature concludes the research.

Energy Management Strategy for P1 + P3 Plug-In Hybrid Electric Vehicles

In order to simultaneously improve the fuel economy and overall performance of plug-in hybrid electric vehicles (PHEVs), this study selected the P1 + P3 configuration as its research object. Through a configuration analysis of hybrid vehicles, it confirmed the feasibility of P1 + P3 configuration-PHEV operating modes. Based on this, a rule-based control strategy was developed, and simulation models for the entire vehicle and control strategy were constructed in both Cruise and MATLAB/Simulink software. The study conducted simulation analysis by combining three sets of Worldwide Harmonized Light vehicles Test Cycle (WLTC) driving cycles to assess the fuel-saving potential of the dual-motor P1 + P3 configuration. The simulation results showed that the vehicle model was reasonably constructed and the proposed control strategy had good control effects on the entire vehicle. Compared to conventional gasoline vehicles, the P1 + P3 configuration PHEV achieved a 67.4% fuel economy improvement, demonstrating a significant enhancement in fuel efficiency with the introduction of electric motors.

Eco-Coasting Controller Using Road Grade Preview: Evaluation and Online Implementation Based on Mixed Integer Model Predictive Control

Coasting is a common method used in eco-driving to reduce fuel consumption by utilizing kinetic energy. However, in order to avoid excessive computation induced by integer coasting maneuvers, the powertrain model used in eco-driving controllers that rely on look-ahead road information has been oversimplified. This oversimplification assumes that the engine goes to idle when coasting, which significantly limits the fuel-saving potential. To address this issue, we propose an eco-coasting strategy that calculates the optimal timing and duration of coasting maneuvers using road information preview. Different from the engine-idling method, two control-oriented coasting methods, fuel cut-off method and engine start/stop method are formulated for the model-based optimal control. To evaluate and choose the best coasting mechanism for eco-coasting strategy, dynamic programming (DP) is performed to provide the globally optimal performance (i.e., benchmark results) for evaluating the engine-idling method, fuel cut-off method, and engine start/stop method. Based on the offline simulation results, the engine start/stop method consistently outperforms the fuel cut-off method in terms of both fuel consumption and travel time. This is attributed to the engine start/stop method eliminating the engine drag torque during deceleration, despite the additional energy cost required for engine restart being taken into account in the modeling, thus providing a fair evaluation. Then, the online performance of the eco-coasting strategy with engine start/stop mechanism is evaluated using Mixed Integer Model Predictive Control (MIMPC). We propose a tailored mixed-integer programming algorithm to facilitate online implementation. Simulation results show that the proposed eco-coasting strategy achieves near-optimal performance compared to DP and outperforms the rule-based method.

Ship speed optimization method combining Fisher optimal segmentation principle

An iterative optimization method that combines the principle of ordered clustering was proposed to address the strong correlation among route segmentation, weather loading, and ship speed optimization. Focusing on a single voyage task on a given route, the speed of an ocean-going container ship was optimized to achieve the minimum fuel consumption of the ship. The verified data-driven method was used to build a ship fuel consumption prediction model, and the Fisher optimal segmentation method was applied to segment ship routes. Subsequently, the speed optimization problem was solved using an iterative optimization method. The optimization results confirmed that the iterative optimization method has significant advantages in realizing route segmentation with the highest weather similarity within the segment. Extensive empirical studies on six case routes revealed the significant fuel-saving potential of the proposed iterative optimization method. Under different routes and weather conditions, the proposed iterative optimization method achieves a ship fuel-saving rate of 2.4 %–5.4 % and provides a reliable technical reference for the shipping industry to reduce the energy consumption and emissions of ships.

Data-driven predictive energy consumption minimization strategy for connected plug-in hybrid electric vehicles

Powertrain electrification incorporating advanced combustion-based dedicated hybrid engines (DHEs) is an effective and affordable approach to automotive energy saving. To explore the concealed fuel-saving potential of connected plug-in hybrid electric vehicles (CPHEVs) and manage engine dynamics, a data-driven predictive energy consumption minimization strategy (D-PECMS) is proposed in a hierarchical framework. The strategy relies on multi-source trip information provided by advanced driving assistance systems (ADAS) combined with maps and realizes power demand prediction by designing a multivariable long-term and short-term memory (M-LSTM) network. The upper level adopts dynamic programming (DP) to realize SOC planning, while the bottom layer utilizes D-PECMS to achieve computationally-efficient energy management with the engine combustion process being regulated in transient. This strategy is featured with predictive SOC tracking ability with less computational burden and look-ahead engine start-stop control. To ensure the credibility of validation, bench test data are used from a high-efficiency spark-induced compression ignition (SICI) engine to model the CPHEV, and the real-world driving scenarios are reconstructed based on real-time traffic data collected in China. The proposed D-PECMS strategy is tested through comprehensive experiments and compared against both the adaptive ECMS and offline DP. The results demonstrate that the proposed strategy effectively reduces fuel consumption by 3.1% and 13.2% in contrast to the adaptive ECMS and rule-based control respectively. Moreover, the D-PECMS strategy successfully avoids frequent engine operation mode switching as well as engine startup and shutdown.

Real-Time Suitable Predictive Control Using SPaT Information from Automated Traffic Lights

Traffic intersections throughout the United States combine fixed, semi-actuated, and fully actuated intersections. In the case of the semi-actuated and actuated intersections, uncertainties are considered in phase duration. These uncertainties are due to car waiting queues and pedestrian crossing. Intelligent transportation systems deployed in traffic infrastructure can communicate Signal and Phase Timing messages (SPaT) to vehicles approaching intersections. In the connected and automated vehicle ecosystem, the fuel savings potential has been explored. Prior studies have predominantly focused on fixed time control for the driver. However, in the case of actuated signals, there is a different and significant challenge due to the randomness caused by uncertainties. We have developed a predictive control using the SPaT information communicated from the actuated traffic intersections. The developed MPC-based algorithm was validated using model-based design platforms such as AMBER®, Autonomie®, MATLAB®, and SIMULINK®. It was observed that the proposed algorithm can save energy in a single phase, in multiple phase scenarios, and in compelled stopping at stop signs when employed considering communications.

Investigating energy saving and climate mitigation potentials in cement production – A case study in Ethiopia

The cement industry is one of the most energy and emission-intensive sectors, accounting for approximately 7% of total-industrial energy use and 7% of global CO2 emissions. This study investigates the potential energy savings and CO2 abatement in the cement plants of Ethiopia. A Benchmarking and Energy Saving Tool for Cement is used to compare the energy use performance of the individual cement plants to best practices. The study reveals that all the surveyed plants are less efficient, with an average energy saving potential of 36% indicating a significant potential for energy efficiency improvement. Then, twenty-eight energy efficiency measures are identified and analyzed using a bottom-up energy conservation supply curve model. The results show that the cost-effective electrical energy and fuel-saving potentials of these measures are estimated to be 99 Gigawatt hours per year which is about 11.5% of the plants’ annual electrical energy consumption and, 2.7 Petajoules per year which is to be 12.5% of the plants’ annual fuel consumption, respectively. The cost-effective fuel measures have an annual average CO2 emission reduction potential of 254 kilo-tonnes per year which covers about 5% of the total CO2 emission. Sensitivity analysis is conducted using the key parameters that show some discrepancy in the base case results. This study could be used as a reference for policymakers to understand the potential for energy savings and CO2 abatement. It could also be used to design policies in improving energy efficiency in the cement sector.

Study of direct water injection on knock suppressing and engine performance of a gasoline engine

Turbocharger technology has become an essential method for the internal combustion engine to improve fuel economy. However, too high a boost pressure leads to too high a temperature in the combustion chamber at the end of the compression stroke, which can cause knocking or worsen abnormal combustion. Water injection technology plays a role in cooling the intake air and components in the cylinder, which can control the combustion process and suppress knock. This work focused on the influence of direct water injection (DWI) on knock suppression and efficiency improvement using a small turbocharged gasoline engine, investigating the fuel-saving potential of DWI and the optimal strategy of DWI for different engine operating conditions. Taking knock intensity (KI) as the evaluation index, KI decreases from 0.052 to 0.04 MPa, and knock limit spark angle (KLSA) increases with increasing water injection. This work shows that the DWI strategy plays a critical role in earlier spark timing, optimized combustion phase, and improved efficiency. Fuel consumption decreases by 11.55% with the optimal DWI strategy at an operating condition of 2000 rpm and a brake mean effective pressure (BMEP) of 1.3 MPa. Moreover, the optimal water injection timing is at −180°CA under various engine loads. Due to the stronger knock tendency under higher load conditions, the knock suppression is less effective for the same amount of water, so more water injection mass is necessary for higher efficiency.

Research on exhaust energy distribution regulation for fuel economy improvement of turbocompound diesel engine

The stringent requirements for reducing CO2 emissions from internal combustion engines promote the development of waste heat recovery (WHR) technologies. Turbocompounding is a promising WHR technology offering fuel-saving potential along with low volume and weight requirements. Meanwhile, the exhaust energy distribution regulation plays a significant role in improving the engine fuel economy. In this study, the coupling influence and mechanism of the variable geometry turbocharger (VGT) turbine and power turbine (PT) regulation on the recovery power and engine performance were studied from novel perspective of exhaust energy distribution. And the cooperative control strategies of VGT rack position and PT speed under whole operating conditions were first proposed. It is concluded that the increase in the VGT rack position and the PT speed leads to a decrease in the proportion of exhaust energy distributed to the VGT turbine, which affects the intake and exhaust conditions, resulting in changes in PT power and net engine output power. In addition, as the engine speed increases under full load, the optimal VGT rack position and PT speed increase. Compared to the base engine, the equivalent brake specific fuel consumption can be reduced by 3.8% at the engine speed of 2200 r/min with the optimized control of the exhaust energy distribution for the turbocompounding. The control strategy of exhaust energy distribution is of great significance to explore the maximum potential of energy efficiency improvement of turbocompound diesel engines.

Influence of ambient conditions on the marine two-stroke engine integrated with a bottoming Rankine cycle system: Energy and exergy analyses

The varied ambient condition brings challenges to highly efficient operation of the marine engine especially when a bottoming Rankine cycle system is integrated. However, few theoretical studies on it were reported. This paper aims at providing a comprehensive energy and exergy study on the marine two-stroke engine and its integrated bottoming Rankine cycle operating at different ambient temperatures. First, the thermodynamic processes of the combined cycle power plant and its tuning methods are described in detail, followed by model building and validation. Parametric studies on the combined cycle power plant operating under varied ambient conditions are then performed from energy and exergy perspectives. It is concluded that the high-pressure tuning can effectively control the scavenging process under varied ambient conditions but has a limited effect on the exergy distributions of the marine engine. With the bypass tuning, every 10 °C rise in the ambient temperature requires a decrease of the bypass ratio by 2% in absolute, which increases the exhaust gas temperature by only 5 °C compared to that of 16 °C in the base engine case. In the bottoming Rankine cycle system, the optimum evaporation pressure is mainly determined by the exhaust temperature rather than the ambient temperature. The fuel-saving potential of the combined cycle with the power turbine tuning reaches up to 7% and is deteriorated with the increasing ambient temperature.

Operation-dependent exergetic sustainability assessment and environmental analysis on a large tanker ship utilizing Organic Rankine cycle system

This study focuses on the novel perspective of marine ORC systems with a detailed marine diesel generator plant simulation integrated with an ORC system model to evaluate environmental impacts and energy efficiency increments by reducing the number or the load of generators by using the ORC system support during operation. It is aimed to analyze the fuel-saving potential and sustainability performance of the power generation plant of a tanker ship when an ORC is integrated. The thermodynamic system simulation determined the fuel consumption of the plant within two years regarding six operation modes. The results show that the optimum working fluid is R1336mzz (Z) for the evaporation pressure of 16 bar. Organic Rankine cycle system integration provided a total fuel-saving of 15% from diesel generators and the total fuel consumption of the vessel was reduced by 5.16%. The sustainability performance of the system was ensured with a novel operation-dependent approach that enhances the exergetic sustainability assessment by considering the operation modes of the vessel and the time spent on these operations for a certain time. The load reduction in the generators resulted in better sustainability performance and the operation-dependent indicators were affected by operations having more working hours.

VOYAGE OPTIMIZATION WITH WIND PROPULSION

Wind propulsion has been proven to produce significant fuel savings on commercial vessels. The typical savings potential of wind propulsion on conventional cargo ships is 5-25%. On the other hand, voyage optimization and weather routing has been shown to produce similarly large fuel savings in the order of 15%. Wind is an intermittent energy source, and it often occurs together with waves, making ships installed with wind propulsion especially interesting from weather routing point of view. This means that a holistic approach is needed when conducting weather routing for ships with wind propulsion. Using detailed simulations, this paper studies how the fuel savings potential of wind propulsion can be further improved by coupling it with state-of-the-art voyage optimization software. Via case study examples, it is shown that the savings potential of wind propulsion can be more than doubled by using voyage optimization.

Traffic Flow Funnels Based on Aircraft Performance for Optimized Departure Procedures

Aircraft departures often follow standardized and restrictive routes intended to guarantee a safe transition to the en-route network. Since the procedures must take the flight performance of many aircraft types into account, they represent a compromise between numerous optima and must be consistent with noise abatement strategies. This paper investigates the concept of departure funnels, in which flights can adopt their optimal profile within a procedural space based on actual flight performance to replace standard routes. For this, an algorithm based on DBSCAN identifies typical traffic flow funnels for a set of radar tracks as reference and individually optimized flight trajectories as preferred funnels. For the latter, an innovative 3D pathfinding grid is developed, which expands dynamically using the specific flight performance of the aircraft type and enables evaluation of operating costs due to wind and fuel consumption. From the clustered traffic flows, a funnel starting at the runway is determined based on the variance of the flight profiles along their mean trajectory. This funnel provides a restricted space for individual trajectory optimization for the day of operation. The procedure is applied using the example of Munich Airport, where the funnel size and the associated fuel-saving potential are determined. The results indicate an average fuel-saving potential of 0.4% with respect to the trip fuel.

Analysis of hydrogen-powered propulsion system alternatives for diesel-electric regional trains

Non-electrified regional railway lines with typically employed diesel-electric multiple units require alternative propulsion systems to meet increasingly strict emissions regulations. With the aim to identify an optimal alternative to conventional diesel traction, this paper presents a model-based assessment of hydrogen-powered propulsion systems with an internal combustion engine or fuel cells as the prime mover, combined with different energy storage system configurations, based on lithium-ion batteries and/or double-layer capacitors. The analysis encompasses technology identification, design, modelling and assessment of alternative powertrains, explicitly considering case-related constraints imposed by the infrastructure, technical and operational requirements. Using a regional railway network in the Netherlands as a case, we investigate the possibilities in converting a conventional benchmark vehicle and provide the railway undertaking and decision-makers with valuable input for planning of future rolling stock investments. The results indicate the highest fuel-saving potential for fuel cell-based hybrid propulsion systems with lithium-ion battery or a hybrid energy storage system that combines both energy storage system technologies. The two configurations also demonstrate the highest reduction of greenhouse gas emissions compared to the benchmark diesel-driven vehicle, by about 25% for hydrogen produced by steam methane reforming, and about 19% for hydrogen obtained from electrolysis of water with grey electricity.

Experimental study on combustion and emission characteristics of LIVC Miller cycle with asynchronous intake valves

An experiment was conducted to explore the performance, combustion, and emission characteristics of the Miller cycle by asynchronous late intake valve closing (LIVC) on a direct-injection turbocharged gasoline engine. Asynchronous LIVC Miller cycle uses geometric compression ratio (GCR) of 12.5:1 (Miller-CR12.5), compared with Otto cycle original engine with GCR of 12.5:1 (Otto-CR12.5) and 10:1 (Otto-CR10). The study indicates that one late intake valve closing can not only realize the Miller cycle but also control the load to effectively reduce the pumping loss. When the brake mean effective pressure (BMEP) is below 4 bar, Miller-CR12.5 shows a very short combustion duration and lower combustion cycle variation compared with the Otto cycle, which solves the problem of low combustion efficiency due to the low actual compression ratio of the Miller cycle. In addition, the Miller cycle of asynchronous LIVC is similar to that of synchronous LIVC, which all can improve knock resistance at medium and high loads. Based on the above factors, Miller-CR12.5 reduces fuel consumption, especially at low and heavy loads. Besides, Miller-CR12.5 shows great fuel-saving potential at high speeds. In terms of emissions, Miller-CR12.5 significantly increases CO and THC emissions within the range of tested loads, but the NOx emissions are reduced under low and high loads.

ADAPTIVE ENERGY MANAGEMENT STRATEGY FOR SUSTAINABLE OPERATION OF HYBRID ELECTRIC VEHICLE

Hybrid electric vehicles (HEVs) in the transportation sector is spearheading the industry towards embracing green technology to ensure the sustainability of the environment. HEVs offer significant reduction of exhaust emissions while retaining vehicle performance achieved via a revolutionary energy management strategy (EMS) which reforms the management of power flow from the dual energy sources of a HEV. However, researchers are faced with challenges to extract the maximum performance out of HEVs due to the contradicting nature between its main objectives, namely vehicle performance, fuel consumption and cost. In this study, an investigation focusing on the fuel-saving potential of a power-split type HEV using a fuzzy logic-based EMS is conducted. The purpose of this research is to explore methods to improve fuel efficiency of a HEV through a smart and adaptive EMS. The power flow in the proposed model is decided based on its current vehicle speed and the global discharge rate value derived from the real-time battery state-of-charge and remaining trip distance. From simulations over standard drive cycles, the proposed controller is able to outperform a rule-based EMS by an improvement of up to 65.4% in terms of fuel consumption which subsequently reduces the volume of pollutants released to the atmosphere.

Long Range Air Traffic Flow Management with Flight-Specific Flight Performance

The increasing need for dynamic in-flight adjustments of a trajectory allows the airport, air traffic control and the airline a high degree of flexibility in terms of in-flight execution. This concept enables numerous optimisation options to jointly meet the requirements of sustainable air transport to increase economic and ecological efficiency, as well as safety. One promising measure is to control the aircraft arrival rate to prevent over-demand in the approach sector around the airport. In so-called Long-Range Air Traffic Management, the arrival time of long-haul flights, in particular, is already controlled many hours before arrival. However, the control options and their effects on arrival time and fuel burn are heavily dependent on flight performance and the (hardly predictable) influence of the weather. In this study, we optimize the arrival time of 26 long-haul flights in the Asia-Pacific region with arrival at Changi Airport within a peak hour considering the arrival rate of medium-haul and short-haul flights. This control is done by speed adjustments and by choosing alternative routes. For the first time, we model each long-haul flight and its control options individually in real weather conditions. We found that speed adjustments should start three to four hours before arriving at the approach sector to maximize the fuel-saving potential of small deviations from the optimal cruising speed, considering the predictability of the arrival time under real weather conditions. Allowing the aircraft to additionally choose an alternative lateral route, different from the filed flight plan, both maximizes the potential for harmonization of the number of aircraft in the approach sector and minimizes the total fuel burn. Unlike speed adjustments, alternative routes changes are effective even during the last hour of the cruise phase.