Search Results (28)

Energy and mobility are currently powered by conventional fuels, and for the specific case of spark ignition (SI) engines, gasoline is dominant. Converting these power-units to hydrogen is an efficient and cost-effective choice for achieving zero-carbon emissions. The use of this alternative fuel can be combined with a circular-economy approach that gives new life to the existing fleet of engines and minimizes the need for added components. In this context, the current work scrutinizes specific aspects of converting a small-size passenger car to hydrogen fueling. The approach combined measurements performed with gasoline and predictive 0D/1D models for correctly including fuel chemistry effects; the experimental data were used for calibration purposes. One particular aspect of H₂ is that it results in lower volumetric efficiency compared to gasoline, and therefore boosting requirements can feature significant changes. The results of the 0D/1D simulations show that one of the main conclusions is that only stoichiometric operation would ensure the reference peak power level; lean fueling featured relative air–fuel ratios too low for ensuring the minimum value of 2 that would allow mitigating NO_x formation. Top speed could be instead feasible in lean conditions, with the same gearbox, but with an extension of the engine speed operating range to 7000 rpm compared to the 3700 rpm reference point with gasoline. Full article

Climate constraints impose greenhouse gas emissions mitigation, and passenger cars have considerable contributions to contribute to this. To improve the engine efficiency of vehicles equipped with conventional powertrains, many technologies are available but with limited individual contribution. The experimental assessment of some technology regarding fuel economy measurement results is sometimes lower than test uncertainties. This study proposes a methodology to compensate the fuel economy for two test uncertainties: vehicle speed variations and battery recharging. The proposed method can be applied when investigating the effects of different vehicle design changes, including engine power cell design. In this work, the proposed method is demonstrated on the test of two oils: one 5W40, the other 5W20, both without FM. Applying the proposed methodology to experimental results, the expected higher influence of oil viscosity on urban conditions could be observed, and the experimental results presented a much better correlation with the vehicle numerical simulation. Applying the proposed compensation, fuel savings of using the 5W20 in comparison to the 5W40 oil was 3.5% under urban conditions and 2.0% on highways. Full article

This article discusses how the introduction of corporate average fuel economy (CAFE) standards in Taiwan, whose market and industry size are much smaller than those of Europe, the United States, Japan, and China, can effectively improve vehicle energy efficiency. It examines the changes in passenger car energy efficiency under Taiwan’s CAFE framework and evaluates CAFE compliance performance to summarize its impacts and challenges. Observations indicate that the strategically flexible CAFE scheme is indeed more effective than mandatory minimum energy performance standards (MEPS) in encouraging manufacturers to comply through various methods. This approach has ultimately increased the overall average fuel efficiency of Taiwan’s passenger cars by 23.5% since 2012, while maintaining the diversity of vehicle models in the market. However, there are challenges to implementing CAFE in a small market, such as difficulties in introducing and promoting high-efficiency models, limited activity in the CAFE credit market, and the current overly favorable policy design. The design of the CAFE mechanism is crucial not only for benchmarking with larger economies but also for taking into account local market conditions and industrial capabilities. Taiwan’s next phase of CAFE must incorporate multi-dimensional adjustments to achieve higher, potentially net-zero vehicle efficiency targets. Full article

In order to improve fuel economy to meet the standard for passenger car oil, a new formulation with good viscosity–temperature performance for gasoline engine oil is required. In this study, coal-to-liquid (CTL) base oil, with a high viscosity index and good low-temperature performance, was selected as the base oil to develop the gasoline engine oil. A systematic study on the molecular interaction between the CTL base oil and the viscosity index improver (VII), including three kinds of hydrogenated styrene diene copolymers (HSD-type) and four kinds of ethylene propylene copolymers (OCP-type), was conducted. It was found that in general, in CTL base oil, the HSD-type VII exhibited a much higher viscosity index, a significantly lower shear stability index, a higher thickening ability, and a lower cold-cranking simulator (CCS) viscosity than that of OCP-type VII. Moreover, when comparing CTL base oil with mineral oil 150N, the combination of CTL base oil and the VII displayed a lower CCS viscosity than that of mineral oil, suggesting it had better low-temperature performance and was able to quickly form a protective oil film on the surface, which was beneficial for the cold start. The functional group distribution state of the VII in base oil was analyzed using synchrotron radiation micro-infrared microscope (SR Micro-IR) technology, which revealed that HSD-1 had a better molecular interaction with CTL6 than 150N because of the better uniformity of the C=C group distribution. Based on this, a SP 0W-20 gasoline engine oil was developed by the combination of CTL base oil and the HSD-1 viscosity index improver, together with an additive package, a polymethacrylate pour point depressant, and a non-silicone defoamer, which showed excellent low-temperature performance, thermal oxidation stability, and detergency performance compared to the reference oil. Full article

The automotive industry is experiencing radical changes under the pressure of institutions that are increasingly reducing the limits on CO₂ and pollutant emissions from road vehicles powered by internal combustion engines (ICEs). A way to decarbonize the transport sector without disrupting current automotive production is the adoption of alternative fuels for internal combustion engines (ICEs). Hydrogen is very attractive, thanks to the zero-carbon content and very high laminar flame speed, allowing for extending the lean burn limit. Other alternative fuels are methanol and ethanol. This work deals with the conversion of a small-sized passenger car powered by a three-cylinder spark ignition (SI) engine for the use of alternative fuels. In particular, the spark timing has been optimized to improve the fuel economy under every operating condition. The optimization procedure is based on the MATLAB/Simulink^® R2024a-GT-Power co-simulation analysis and minimizes the fuel consumption by varying the spark timing independently for each cylinder. In particular, at full load, the algorithm reduces the spark timing only for the cylinder in which knock is detected, reducing fuel consumption by about 2% compared to the base calibration. This approach will be adopted in future activities to understand how the use of alternative fuels affects the ignition control strategy. Full article

The pursuit of sustainable and environmentally friendly transportation has led to the exploration of alternative fuel sources, among which hydrogen stands out prominently. This work delves into the potential of hydrogen fuel for internal combustion engines (ICEs), emphasizing its capacity to ensure the required performance levels while concurrently enhancing overall efficiency. The integration of a mild hybrid powertrain in a small size passenger car was considered for obtaining a twofold advantage: mitigating power loss due to low volumetric efficiency and increasing fuel economy. A comprehensive approach combining 0D/1D modeling simulations and experimental validations was employed on a gasoline-powered small size ICE, considering its conversion to hydrogen, and mild hybridization. Vehicle simulations were performed in AVL Cruise M and validated against experimental data. Various electric motors were scrutinized for a small size battery pack typical of mild hybrid vehicles. Furthermore, the paper assesses the potential range achievable with the hydrogen-powered hybrid vehicle and compares it with the range reported by the manufacturer for the original gasoline and pure electric version. In terms of global results, these modifications were found to successfully improve efficiency compared to baseline gasoline and hydrogen fueling. Additionally, performance gains were achieved, surpassing the capabilities of the original gasoline vehicle despite its intrinsic volumetric efficiency limitations when using hydrogen. Along with the conversion to hydrogen and thus zero-carbon tail-pipe emissions, incorporating a Start/Stop system, and the integration of mild hybrid technology with energy recuperation during braking, overall efficiency was enhanced by up to 30% during urban use. Furthermore, the hybridization implemented in the H₂ version allows an autonomy comparable to that of the electric vehicle but with evident shorter refilling times. Specific aspects of the 48 V battery management are also scrutinized. Full article

One route to reducing global CO₂ emissions is to improve the energy efficiency of machines. Even small improvements in efficiency can be valuable, especially in cases where an efficiency improvement can be realized over many millions of newly produced machines. For example, conventional passenger car combustion engines are being downsized (and also downspeeded). Increasingly, they are running on lower-viscosity engine lubricants (such as SAE 0W-20 or lower viscosity grades) and often also have stop–start systems fitted (to prevent engine idling when the vehicle is stopped). Some of these changes result in higher levels of mixed and boundary friction, and so accurate estimation of mixed/boundary friction losses is becoming of increased importance, for both estimating friction losses and wear volumes. Traditional approaches to estimating mixed/boundary friction, which employ real area of contact modelling, and assumptions such as the elastic deformation of asperities, are widely used, but recent experimental data suggest that some of these approaches underestimate mixed/boundary friction losses. In this paper, a discussion of the issues involved in reliably estimating mixed/boundary friction losses in machine elements is undertaken, highlighting where the key uncertainties lie. Mixed/boundary lubrication losses in passenger car and heavy-duty internal combustion engines are then estimated and compared with published data, and a detailed description of how friction is related to fuel consumption in these vehicles, on standard fuel economy driving cycles, is given. Knowing the amount of fuel needed to overcome mixed/boundary friction in these vehicles enables reliable estimates to be made of both the financial costs of mixed/boundary lubrication for today’s vehicles and their associated CO₂ emissions, and annual estimates are reported to be approximately USD 290 billion with CO₂ emissions of 480 million tonnes. Full article

Hydrogen is seen as a prime choice for complete replacement of gasoline so as to achieve zero-emissions energy and mobility. Combining the use of this alternative fuel with a circular economy approach for giving new life to the existing fleet of passenger cars ensures further benefits in terms of cost competitiveness. Transforming spark ignition (SI) engines to H₂ power requires relatively minor changes and limited added components. Within this framework, the conversion of a small-size passenger car to hydrogen fueling was evaluated based on 0D/1D simulation. One of the methods to improve efficiency is to apply exhaust gas recirculation (EGR), which also lowers NO_x emissions. Therefore, the previous version of the quasi-dimensional model was modified to include EGR and its effects on combustion. A dedicated laminar flame speed model was implemented for the specific properties of hydrogen, and a purpose-built sub-routine was implemented to correctly model the effects of residual gas at the start of combustion. Simulations were performed in several operating points representative of urban and highway driving. One of the main conclusions was that high-pressure recirculation was severely limited by the minimum flow requirements of the compressor. Low-pressure EGR ensured wider applicability and significant improvement of efficiency, especially during partial-load operation specific to urban use. Another benefit of recirculation was that pressure rise rates were predicted to be more contained and closer to the values expected for gasoline fueling. This was possible due to the high tolerance of H₂ to the presence of residual gas. Full article

The negative consequences of toxic emissions from internal combustion engines, energy security, climate change, and energy costs have led to a growing demand for clean power sources in the automotive industry. The development of eco-friendly vehicle technologies, such as electric and hydrogen vehicles, has increased. This article investigates whether hydrogen vehicles will replace electric vehicles in the future. The results showed that fuel-cell cars are unlikely to compete with electric cars. This is due to the advancements in electric vehicles and charging infrastructure, which are becoming more cost-effective and efficient. Additionally, the technical progress in battery electric vehicles (BEVs) is expected to reduce the market share of fuel-cell electric vehicles (FCEVs) in passenger vehicles. However, significant investments have been made in hydrogen cars. Many ongoing investments seem to follow the sunk cost fallacy, where decision-makers continue to invest in an unprofitable project due to their already invested resources. Furthermore, even with megawatt charging, fuel-cell trucks cost more than battery-powered electric trucks. The use cases for fuel-cell electric trucks are also much more limited, as their running expenses are higher compared to electric cars. Hydrogen vehicles may be beneficial for heavy transport in remote areas. However, it remains to be seen if niche markets are large enough to support fuel-cell electric truck commercialization and economies of scale. In summary, we believe that hydrogen vehicles will not replace electric cars and trucks, at least before 2050. Full article

Passenger cars account for the largest share of GHG emissions in the road sector. However, given that the number of heavy-duty vehicles registered is lower but accounts for about a quarter of GHG emissions in the road sector, it is necessary to reduce carbon dioxide (CO₂) emissions by improving the fuel efficiency of heavy-duty vehicles. However, experiments using dynamometers during the vehicle development process consume a lot of time and cost. Conversely, simulations can quantitatively analyze the sensitivity of parameters and accelerate optimization. Therefore, in this study, we modeled a heavy-duty vehicle using an AVL Cruise simulation and analyzed the effects of payload, air drag coefficient, and rolling resistance on fuel economy, CO₂ emission, and the valid window ratio among the moving average window (MAW) for three driving routes. When the average vehicle speed was higher, the effect of the air drag coefficient on fuel economy was high. Additionally, when the average vehicle speed was lowered, the effect of the reduced rolling resistance on improving fuel efficiency was higher than that of the reducing air drag. Thus, the fuel efficiency improvement rate according to each 10% decrease in rolling resistance was higher by 2.2%, on average, in the low average speed route. Additionally, it was confirmed that the valid window ratio was high when driving in a section with a high vehicle speed first. Thus, the valid window ratio was almost 100% in the test of the route conditions starting from the highway section. Full article

In the current scenario, where environmental concern determines the evolution of passenger cars, hybrid electric vehicles (HEV) represent a hub in the automotive sector to reach net-zero CO₂ emissions. To fully exploit the energy conversion potential of advanced powertrains, proper energy management strategies are mandatory. In this work, a simulation study is presented, aiming at developing a new control strategy for a P3 parallel plug-in HEV (PHEV). The simulation model is built on MATLAB/Simulink. The proposed strategy is based on an alternative utilization of the thermal engine and electric motor to provide the vehicle power demand (efficient thermal/electric skipping strategy (ETESS)). An adaptive function is then introduced to develop a charge-blended control strategy. Fuel consumption along different driving cycles is evaluated by applying the novel adaptive-ETESS (A-ETESS). To have a proper comparison, the same adaptive function is built on the equivalent consumption minimization strategy (ECMS). Processor-in-the-loop (PIL) simulations are performed to benchmark the A-ETESS. Simulation results highlighted that the proposed strategy provides for a fuel economy similar to ECMS (worse of about 2.5% on average) and a computational effort reduced by 99% on average, opening the possibility of real-time on-vehicle applications. Full article

Under the dual−carbon goal, the research on energy conservation and emission reduction of new energy vehicles has once again become a current hotspot, and plug−in hybrid electric vehicles (PHEVs) are the first to bear the brunt. In order to improve the fuel economy of PHEV, an adaptive energy management strategy is designed on the basis of the intelligent prediction of driving cycles. Firstly, according to the vehicle dynamics model, the optimal control objective function of PHEV is established, and the relationship between vehicle fuel consumption and driving cycle is analyzed. Secondly, the initial weights and threshold of the backpropagation (BP) neural network are optimized using the particle swarm optimization (PSO) algorithm, and a PSO−BP neural network vehicle velocity prediction controller is established. Thirdly, combined with the approximate equivalent consumption minimization strategy (ECMS) algorithm to calculate the optimal initial equivalent factor in the prediction time domain, the fast−planning SOC and PI control are introduced to determine the optimal equivalent factor sequence, and the optimal torque distribution ratio of the engine and motor is calculated. Lastly, three different energy management strategies are simulated and verified under six China light−duty vehicle test cycle−passenger car (6*CLTC−P) driving cycles. Simulation results show that the established velocity prediction model has good prediction accuracy, and the proposed adaptive energy management strategy based on prediction is 9.85% higher than the rule−based strategy in terms of fuel saving rate and 5.30% higher than the ECMS strategy without prediction, which further improves the fuel saving potential of PHEV. Full article

The Equivalent Consumption Minimization Strategy (ECMS) is a well-known control strategy for the definition of optimal power-split in hybrid-electric vehicles, because of its effectiveness and reduced calibration effort. In this kind of Energy Management Systems (EMS), the correct identification of an equivalence factor (K), which translates electric power in equivalent fuel consumption, is of paramount importance. To guarantee charge sustaining operation, the K factor must be adjusted to different mission profiles. Adaptive ECMS (A-ECMS) techniques have thus been introduced, which automatically determine the optimal equivalence factor based on the vehicle mission. The aim of this research activity is to assess the potential in terms of fuel consumption and charge sustainability of different A-ECMS techniques on a gasoline hybrid-electric passenger car. First, the 0D vehicle and powertrain model was developed in the commercial CAE software GT-SUITE. An ECMS-based EMS was used to control the baseline powertrain and three alternative versions of an auto-adaptive algorithm were implemented on top of that. The first A-ECMS under study was based on feedback from the battery State of Charge, while the second and third on a Driving Pattern Recognition/Prediction algorithm. Fuel consumption was assessed using the New European Driving Cycle (NEDC), the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) and Real Driving Emissions (RDE) driving cycles by means of numerical simulation. A potential improvement of up to 4% Fuel Economy was ultimately achieved on an RDE driving cycle with respect to the baseline ECMS. Full article

This paper is concerned with the development and performance of high-energy density electrochemical supercapacitors (ECCs) and their application in HEVs, PHEVs, and HFCVs. Detailed test data are shown for the Skeleton Technology 5000 F carbon/carbon EDLC device and the Aowei 9000 F hybrid (4 V) supercapacitor (HSC). The EDLC device had an energy density of 8.4 Wh/kg and the hybrid SC had an energy density between 30 and 65, depending on its rated voltage and the power of the discharge. These energy densities are significantly higher than previous ECCs tested. They indicate that good progress is being made in increasing the energy density of commercial ECCs. Vehicle applications of the advanced ECCs were evaluated based on Advisor simulations on city and highway driving cycles. Simulations were made for six vehicle types ranging from compact passenger cars to Class 8 long haul trucks. The fuel economy was calculated for each vehicle type using a lithium battery, the EDLC Skeleton Technology capacitor and the two Aowei hybrid capacitors as energy storage in the powertrain. The 4.1 V hybrid capacitor in all cases was lighter and smaller than the lithium battery. The fuel economies of the HEVs on the FUDS cycle were significantly higher (30–50%) than that of the corresponding ICE vehicle, except for the long haul truck, for which the fuel economy improvement was 20%. In almost all cases, the fuel economy improvement was highest when using the 4.1 V hybrid capacitor. Simulations were also run for fuel cell-powered vehicles. For the fuel cell vehicles, the fuel economies using the three energy storage technologies varied only slightly. For all the fuel cell vehicles simulated, the 4.1 V hybrid capacitor was the lightest and smallest of the energy storage options, and produced the best fuel economy. As in the case of HEVs, the hybrid capacitors appeared to be the best option for energy storage in fuel cell vehicle applications. Full article

With the increase of the requirement for the economy of vehicles and the strengthening of the concept of environmental protection, the development of future vehicles will develop in the direction of high efficiency and cleanliness, and the current power system of vehicles based on traditional fossil fuels will gradually transition to hybrid power. As an essential technological direction for new energy vehicles, the development of fuel cell passenger vehicles is of great significance in reducing transportation carbon emissions, stabilizing energy supply, and maintaining the sustainable development of the automotive industry. To study the fuel economy of a passenger car with the proton exchange membrane fuel cell (PEMFC) during the operating phase, two typical PEMFC passenger cars, test vehicles A and B, were compared and analyzed. The hydrogen consumption and hydrogen emission under two operating conditions, namely the different steady-state power and the Chinese Vehicle Driving Conditions-Passenger Car cycle, were tested. The test results show the actual hydrogen consumption rates of vehicle A and vehicle B are 9.77 g/kM and 8.28 g/kM, respectively. The average hydrogen emission rates for vehicle A and vehicle B are 1.56 g/(kW·h) and 5.40 g/(kW·h), respectively. By comparing the hydrogen purge valve opening time ratio, the differences between test vehicles A and B in control strategy, hydrogen consumption, and emission rate are analyzed. This study will provide reference data for China to study the economics of the operational phase of PEMFC vehicles. Full article