Fuel Efficiency Improvement Research Articles

Quantifying autonomous vehicles national fuel consumption impacts: A data-rich approach

Autonomous vehicles are drawing significant attention from governments, manufacturers and consumers. Experts predict them to be the primary means of transportation by the middle of this century. Recent literature shows that vehicle automation has the potential to alter traffic patterns, vehicle ownership, and land use, which may affect fuel consumption from the transportation sector. In this paper, we developed a data-rich analytical framework to quantify system-wide fuel impacts of automation in the United States by integrating (1) a dynamic vehicle sales, stock, and usage model, (2) an historical transportation network-level vehicle miles traveled (VMT)/vehicle activity database, and (3) estimates of automation’s impacts on fuel efficiency and travel demand. The vehicle model considers dynamics in vehicle fleet turnover and fuel efficiency improvements of conventional and advanced vehicle fleet. The network activity database contains VMT, free-flow speeds, and historical speeds of road links that can help us accurately identify fuel-savings opportunities of automation. Based on the model setup and assumptions, we found that the impacts of automation on fuel consumption are quite wide-ranging—with the potential to reduce fuel consumption by 45% in our “Optimistic” case or increase it by 30% in our “Pessimistic” case. Second, implementing automation on urban roads could potentially result in larger fuel savings compared with highway automation because of the driving features of urban roads. Through scenario analysis, we showed that the proposed framework can be used for refined assessments as better data on vehicle-level fuel efficiency and travel demand impacts of automation become available.

Subgrid Model Influence in Large Eddy Simulations of Non-reacting Flow in a Gas Turbine Combustor

Fuel efficiency improvement and harmful emission reduction are the paramount driving forces for development of gas turbine combustors. Lean-burn combustors can accomplish these goals, but require specific flow topologies to overcome their sensitivity to combustion instabilities. Large Eddy Simulations (LES) can accurately capture these complex and intrinsically unsteady flow fields, but estimating the appropriate numerical resolution and subgrid model(s) still remain challenges. This paper discusses the prediction of non-reacting flow fields in the DLR gas turbine model combustor using LES. Several important features of modern gas turbine combustors are present in this model combustor: multiple air swirlers and recirculation zones for flame stabilisation. Good overall agreement is obtained between LES outcomes and experimental results, both in terms of time-averaged and temporal RMS values. Findings of this study include a strong dependence of the opening angle of the swirling jet inside the combustion chamber on the subgrid viscosity, which acts mainly through the air mass flow split between the two swirlers in the DLR model combustor. This paper illustrates the ability of LES to obtain accurate flow field predictions in complex gas turbine combustors making use of open-source software and computational resources available to industry.

Fuel efficiency and air pollutant concentrations of wood-burning improved cookstoves in Malawi: Implications for scaling-up cookstove programs

Developing countries are grappling with how to reduce household air pollution (HAP) from cooking with solid fuels and the traditional three stone fire (TSF). Laboratory studies have shown that improved cookstoves may offer reductions in fuel use, emissions of carbon monoxide (CO) and fine particulate matter (PM2.5), yet there is limited evidence from “real-world” settings showing how improved stoves perform compared to the traditional TSF. Our study takes place in a semi-controlled setting in Malawi and was designed to quantify fuel efficiency improvements and air pollutant concentration reductions capabilities of two improved cookstoves. We perform a Water Boiling Test to compare the TSF with the locally produced clay stove known as the Chitetezo Mbaula (CM) and the Philips gasifying stove. We find that the CM uses 53% of the fuel used by the traditional TSF, and produces 59% of CO, and 50% of PM2.5 of the TSF. The Philips stove uses 31% of the fuel, and produces 38% of CO, and 22% of PM2.5 of the TSF. We consider the potential for the wide-scale adoption of these technologies given their relative costs and conclude that lower-cost, intermediate quality cookstoves are an important and realistic first step toward reducing HAP.

A Combined Organic Rankine Cycle With Double Modes Used for Internal Combustion Engine Waste Heat Recovery

A combined organic Rankine cycle (ORC) was proposed for both engine coolant energy recovery (CER) and exhaust energy recovery (EER), and it was applied to a gasoline direct injection (GDI) engine to verify its waste heat recovery (WHR) potential. After several kinds of organic working medium were compared, R123 was selected as the working fluid of this ORC. Two cycle modes, low-temperature cycle and high-temperature cycle, were designed according to the evaporation way of working fluid. The working fluid is evaporated by coolant heat in low-temperature cycle but by exhaust heat in high-temperature cycle. The influence factors of cycle performance and recovery potential of engine waste heat energy were investigated by cycle simulation and parametric analysis. The results show that recovery efficiency of waste heat energy is influenced by both engine operating conditions and cycle parameters. At 2000 r/min, the maximum recovery efficiency of waste heat energy is 7.3% under 0.2 MPa brake mean effective pressure (BMEP) but 10.7% under 1.4 MPa BMEP. With the combined ORC employed, the fuel efficiency improvement of engine comes up to 4.7% points under the operations of 2000 r/min and 0.2 MPa BMEP, while it further increases to 5.8% points under the operations of 2000 r/min and 1.4 MPa BMEP. All these indicate that the combined ORC is suitable for internal combustion (IC) engine WHR.

Erratum to: Impact of Emerging Engine and After-Treatment Technologies for Improved Fuel Efficiency and Emission Reduction for the Future Rail Diesel Engines

The future stringent emission limits and fuel-saving requirements for non-road engines, in particular for the rail sector, require further research investments both on engine and after-treatment technologies. Therefore, the aim of this study is to identify, mainly on a literature data base, the most promising emerging engine technologies (waste heat recovery, turbocharging, etc.) and exhaust after-treatment systems (de-NO x catalyst systems, particulate filters, etc.) for improved fuel efficiency and emissions reduction of rail diesel engines. The considered technologies are currently from production series or under development mostly in the on-road research domain. The approach taken has been to gather available information and data from research and industry sources for the most promising emerging technologies of on-road heavy-duty (HD) engines. The collected data have been properly analyzed and elaborated in order to identify the most transferable data from road to the rail sector. The study is one of the results of a project carried out within the 7th European Framework program in which several academic and industrial partners have participated. Engine side and exhaust after-treatment system side technologies are discussed separately. The former takes into account quantitative data from the literature survey, mainly in terms of fuel efficiency benefits, and summarizes the evaluation in a return on investment calculation on the base of a reference rail engine cost. In the latter, essentially qualitative information has been collected. The analysis has been carried out by means of spider diagrams that are used to show the potential of the grouped after-treatment technologies in terms of pollutant emission reduction, size/weight reduction, technology maturity, and cost reduction. The results indicate that the emerging engine technologies are mostly about engine efficiency improvements, of which waste heat recovery shows the greatest potential in terms of fuel efficiency improvement. On the after-treatment system side, the integration of multiple after-treatment functionalities into a single device is particularly attractive for rail applications because it could significantly decrease space and weight requirements, as could the use of alternative to urea media for ammonia storage in the case of selective catalytic reduction (SCR) system functionalities.

Economics and environmental implications of fuel efficiency improvement in Malaysia: A computable general equilibrium approach

The continued increase in urbanization and vehicle ownership poses an increasing challenge in curbing the rising energy consumption and CO2 emissions in Malaysia. For more than a decade, road vehicles have been the leading contributor in the country, due mainly to their heavy reliance on petroleum products, particularly gasoline and diesel. The efficient utilization of petroleum products becomes paramount in reducing Malaysia’s overall CO2 emissions in the land transportation sector. The timely abolition of petroleum product subsidies in 2014 may provide a financial source to support the improvement of petroleum product efficiency. The primary purpose of this paper is to examine the impact on economic growth and sectoral performance with fuel subsidy savings being reallocated to the biofuel industry for research and development purposes. The study then investigates whether an environmental tax on petroleum products could induce more energy saving and emission control. This research applies the computable general equilibrium modeling for the simulation, as it takes into account the interaction between petroleum products and the economy as a whole. The Malaysia Input-Output Tables 2010 is the main database used in the simulation. The simulation results found that fuel efficiency improvement could produce a double dividend effect with simultaneous benefits on the economy and environmental quality. A simultaneous implementation with fuel tax policy appears to be one suitable complementary measure for a further emission cut. However, sufficient compensation schemes might be necessary to stimulate economic activities over time. Based on the simulation results, policymakers should emphasize fuel efficiency improvement as a crucial strategy to control the rising energy consumption and emissions in Malaysia.

Application of Analytic Hierarchy Process (AHP) in the analysis of the fuel efficiency in the automobile industry with the utilization of Natural Fiber Polymer Composites (NFPC)

A systematic method of material analysis aiming for fuel efficiency improvement with the utilization of natural fiber reinforced polymer matrix composites in the automobile industry is proposed. A multi-factor based decision criteria with Analytical Hierarchy Process (AHP) was used and executed through MATLAB to achieve improved fuel efficiency through the weight reduction of vehicular components by effective comparison between two engine hood designs. The reduction was simulated by utilizing natural fiber polymer composites with thermoplastic polypropylene (PP) as the matrix polymer and benchmarked against a synthetic based composite component. Results showed that PP with 35% of flax fiber loading achieved a 0.4% improvement in fuel efficiency, and it was the highest among the 27 candidate fibers.

Fuel Efficiency Improvements: Feedback Mechanisms and Distributional Effects in the Oil Market

We study the interactions between fuel efficiency improvements in the transport sector and the oil market, where the efficiency improvements are policy-induced in certain regions of the world. We are especially interested in feedback mechanisms of fuel efficiency such as the rebound effect, carbon leakage and the “green paradox”, but also the distributional effects for oil producers. An intertemporal numerical model of the international oil market is introduced, where OPEC-Core producers have market power. We find that the rebound effect has a noticeable effect on the transport sector, with the magnitude depending on the oil demand elasticity. In the benchmark simulations, we calculate that almost half of the energy savings may be lost to a direct rebound effect and an additional 10% to oil price adjustments. In addition, there is substantial intersectoral leakage to other sectors through lower oil prices in the regions that introduce the policy. There is a small green paradox effect in the sense that oil consumption increases initially when the fuel efficiency measures are gradually implemented. Finally, international carbon leakage will be significant if policies are not implemented in all regions; we estimate leakage rates of 35% or higher when only major consuming regions implement fuel economy policies. Non-OPEC producers will to a larger degree than OPEC producers cut back on its oil supply as a response to fuel efficiency policies due to high production costs.

Characterisation, control, and energy management of electrified turbocharged diesel engines

The electrification of engine components offers significant opportunities for fuel efficiency improvements. The electrified turbocharger is one of the most attractive options since it recovers part of the engine exhaust gas mechanical energy to assist boosting. Therefore, the engine can be downsized through improved transient responsiveness. In the electrified turbocharger, an electric machine is mounted on the turbine shaft and changes the air system dynamics, so characterisation of the new layout is essential. A systematic control solution is required to manage energy flows in the hybrid system. In this paper, a framework for characterisation, control, and energy management for an electrified turbocharged diesel engine is proposed. The impacts of the electric machine on fuel economy and air system variables are analysed. Based on the characterisation, a two-level control structure is proposed. A real-time energy management strategy is employed as the supervisory level controller to generate the optimal values of critical variables, while a model-based multi-variable controller is designed as the low level controller to track the values. The two controllers work together in a cascade to address both fuel economy optimisation and battery state-of-charge maintenance. The proposed control strategy is validated on a high fidelity physical engine model. The tracking performance shows the proposed framework is a promising solution in regulating the behavior of electrified engines.

Improvement of Fuel Efficiency of Passenger Cars by Taking Advantage of Tribology

Improvement of Fuel Efficiency of Passenger Cars by Taking Advantage of Tribology

Метод повышения топливной экономичности дизель-генераторной установки тепловоза в условиях эксплуатации

Метод повышения топливной экономичности дизель-генераторной установки тепловоза в условиях эксплуатации

A Study of Adaptive Cruise Control System to Improve Fuel Efficiency

This paper presents modelling and control strategy of adaptive cruise control system. The algorithm utilize the information of subject and target vehicles to against waste energy. The Control strategy operates to follow the preceding vehicle with the optimal fuel consumption speed trajectory while the target vehicle is in the control distance range. This algorithm focuses on reducing unnecessary acceleration and deceleration. The simulation is conducted by Matlab/Simulink® and CarSim® simulator to verify its effectiveness.

연비개선 및 소음저감을 위한 지로터 최적설계 (타원 1-타원형 인벌루트-타원2)

연비개선 및 소음저감을 위한 지로터 최적설계 (타원 1-타원형 인벌루트-타원2)

Study of the abatement options available to reduce carbon emissions from Australian international flights

ABSTRACTIn 2012, 14 airlines emitted a combined total of 13.1 Mt of CO2 while flying 72% of the international passengers into and out of Australia. In the Asia-Pacific region, passengers and cargo traffic are predicted to grow at 6% and 5% per annum respectively from 2013 to 2033. The International Air Transport Association has committed to an average fuel efficiency improvement of 1.5% from 2009 to 2020, carbon-neutral growth from 2020, and 50% reduction in CO2 emissions by 2050 compared to 2005 levels. To develop policies for reducing aircraft emissions, policy makers need to consider the effectiveness of abatement options used to curb the growth in emissions. In this study, five scenarios were developed to evaluate abatement options that have been or will be implemented by airlines flying on Australian international routes. Analysis reveals that by acquiring more efficient aircraft and increasing the average number of passengers per flight by 10%, 15.6 Mt and 29.2 Mt of CO2 would likely be emitted in 2020 and 2033 respectively, with CO2 emissions increasing at 6.1% per annum and CO2 efficiency dropping at 1.6% per annum. To achieve carbon-neutral growth after 2020, additional abatement options will be required to reduce CO2 emissions by a further 13.6 Mt (i.e., 46.6%) in 2033.

Oil drilling rig diesel power-plant fuel efficiency improvement potentials through rule-based generator scheduling and utilization of battery energy storage system

This paper presents the development of a rule-based energy management control strategy suitable for isolated diesel power-plants equipped with a battery energy storage system for peak load shaving. The proposed control strategy includes the generator scheduling strategy and peak load leveling scheme based on current microgrid active and reactive power requirements. In order to investigate the potentials for fuel expenditure reduction, 30days-worth of microgrid power flow data has been collected on an isolated land-based oil drilling rig powered by a diesel generator power-plant, characterized by highly-variable active and reactive load profiles due to intermittent engagements and disengagements of high-power electric machinery such as top-drive, draw-works and mud-pump motors. The analysis has indicated that by avoiding the low-power operation of individual generators and by providing the peak power requirements (peak shaving) from a dedicated energy storage system, the power-plant fuel efficiency may be notably improved. An averaged power flow simulation model has been built, comprising the proposed rule-based power flow control strategy and the averaged model of a suitably sized battery energy storage system equipped with grid-tied power converter and state-of-charge control system. The effectiveness of the proposed rule-based strategy has been evaluated by means of computer simulation analysis based on drilling rig microgrid active and reactive power data recorded during the 30day period. The analysis has indicated that fuel consumption of thus modified drilling rig diesel generator power-plant can be reduced by about 12% compared to current practice in the field relying on human operator-based decision making, which would also result in proportional reduction of carbon-dioxide emissions. Finally, the analysis has also shown that the return-of-investment period for the considered battery energy storage system might be between one and two years depending on the power-plant utilization (duty) ratio.

Design and optimization of automotive thermoelectric generators for maximum fuel efficiency improvement

Automotive fuel efficiency can be increased by thermoelectric power generation using exhaust waste heat. A high-temperature thermoelectric generator (TEG) that converts engine exhaust waste heat into electricity is simulated based on a light-duty passenger vehicle with a 4-cylinder gasoline engine. Strategies to optimize TEG configuration and heat exchanger design for maximum fuel efficiency improvement are provided. Through comparison of stainless steel and silicon carbide heat exchangers, it is found that both the optimal TEG design and the maximum fuel efficiency increase are highly dependent on the thermal conductivity of the heat exchanger material. Significantly higher fuel efficiency increase can be obtained using silicon carbide heat exchangers at taller fins and a longer TEG along the exhaust flow direction when compared to stainless steel heat exchangers. Accounting for major parasitic losses, a maximum fuel efficiency increase of 2.5% is achievable using newly developed nanostructured bulk half-Heusler thermoelectric modules.

Analyzing the moderating effects of respondent type and experience on the fuel efficiency improvement in air transport using structural equation modeling

The limited nature of oil, and hence aviation fuel is increasingly becoming a restraining factor for the air transport industry. Also, fuel efficiency is crucial for commercial air transport as fuel is one of the most costly operating parameters for an airline. This study employs structural equation modelling (SEM) approach to identify key dimensions influencing fuel efficiency in air transport (FEAT) and to explore the correlational relationships among constructs from the perspectives of fuel efficiency improvement. Self-administered questionnaires were used to collect data from 375 aviation experts. Correlation, multi-group moderation analysis, and interaction using structural equation model were used to analyses these data. The results and applications of SEM evolve a variety of findings; aircraft technology & design, aviation operations infrastructure, socioeconomic & political measures, and alternative fuels & fuel properties, and aviation infrastructure are proved to be the five key influential dimensions affecting the fuel efficiency and have a positive effect on the FEAT. In addition, the moderating effect of industry type and experience were established. The results also showed that no significant interaction effect between dimensions of FEAT. The findings of this research can provide air transport valuable information for designing appropriate strategy for fuel efficiency improvement.

Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three-way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in the oxygen-rich exhaust. Thus, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategymore » based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. 15% excess NH3 production over a 1:1 NH3:NOX ratio was required (via longer rich cycle timing) to achieve 99.7% NOX conversion at an SCR average inlet temperature of 350 C. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher temperatures, NH3 oxidation becomes important and limits NH3 availability for NOX reduction. At the engine conditions studied here, greater than 99% NOX conversion was achieved with passive SCR while delivering fuel efficiency benefits ranging between 6-11% compared with stoichiometric operation.« less

Feasibility Study of a Scroll Expander for Recycling Low-Pressure Exhaust Gas Energy from a Vehicle Gasoline Engine System

The growing number of vehicles on the road has led to a rapid increase in fuel consumption and toxic gas emissions, so the challenges in fuel efficiency improvement and reduction of CO2 and NOx emissions have always been on the top agenda of the automotive industry. The paper presents a feasibility study of recovering the low-pressure exhaust gas energy via by-pass connection of a scroll expander to the engine system exhaust. The paper starts with the description of the proposed new exhaust energy recycling scheme and the mathematical modelling of the system. A feasibility study is carried out to investigate whether this new scheme can work with the engine operation conditions specified by the engine test data. The initial study indicated that the scroll expander structure needs to be modified; otherwise, it cannot be used for exhaust energy recovery. The experimental test and simulation results presented in this paper indicate that it is feasible to recover the low-pressure exhaust gas energy using a scroll expander with a modified structure. The proposed energy recovery system has the potential to produce over 400 W power output with over 90% of engine exhaust flow recycling.

A CFD study on spray characteristics of heavy fuel oil-based microalgae biodiesel blends under ultra-high injection pressures

Blended fuels have intrinsic potential for substitution with petro fuel for the purpose of emission control and fuel efficiency improvement. Therefore, in the current study, non-reacting spray characteristics of heavy fuel oil (HFO) combined with microalgal biodiesel as blended fuel under ultra-high injection pressure is numerically investigated. To accomplish this task with spray morphology, the characteristics of spray penetration, spray cone angle, spray volume and Sauter Mean Diameter (SMD) are studied. The OpenFOAM CFD toolbox is employed with Eulerian–Lagrangian multiphase formulation for fuel discrete phase interacting with gaseous continuous phase modeling. Lagrangian particle tracking (LPT) method is applied for the fuel droplet tracking by Lagrangian scheme. Moreover, hybrid breakup model of KH-RT and k − ϵ as the standard model in Reynolds Averaged Navier–Stokes (RANS) are used for liquid fuel core breakup and turbulence modeling, respectively. Computational results are validated against existing experimental data for HFO and good agreements are displayed. Longer spray penetration length with sharper tip, wider spray cone angle, more obese spray volume and lower SMD are obtained for the blended fuels. Overall, it is concluded that HFO-microalgal biodiesel blended fuels present a better fuel–air mixture and improves atomization procedure under high and ultra high injection pressures.