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Abstract Carbon fiber reinforced plastic (CFRP) has been used in automobiles as well as airplanes. Because of its light weight and high strength, CFRP is a good choice for making vehicle bodies lighter, which would improve fuel economy. Conventional metal bodies provide a convenient body return for electric wiring and offer good shielding against electromagnetic fields. Although CFRP is a conductor, its conductivity is much lower than that of metals. Therefore, CFRP bodies are usually not useful for electric wiring. In thunderstorms, an automotive body is considered to be a Faraday cage that protects the vehicle’s occupants from the potential harms of lightning. Before CFRP becomes widely applied to automotive bodies, its electric and electromagnetic properties need to be investigated in order to determine whether it also works as a Faraday cage against lightning. In this article, CFRP and metal body vehicles were tested under artificial lightning.

Abstract The objective of this work is to develop an integrated HVAC-VEHICLE model for climate control studies. A published lumped parameter based HVAC model has been used as the framework for the HVAC modeling with some modifications to realize the climate control and to improve the robustness of the model. R134a (1,1,2,2-Tetrafluoroethane) has been used as the refrigerant fluid in this study. The stand-alone HVAC model has been compared qualitatively with the experimental works available in the literature. The experimental trends of the thermodynamic and performance related parameters of HVAC are reasonably well captured by the HVAC model. In particular, Coefficient of Performance (CoP) was found to decrease with increase in compressor speed and increase in ambient temperature but increase with increase in evaporator blower mass flow rate.

Abstract Investigation of vehicle resistant forces and power losses is of crucial importance owing to current state of energy consumption in transport sector. Meanwhile, considerable portion of resistant forces in a ground vehicle is traced back to tires. Pneumatic tires are known to be a source of energy dissipation as a consequence of their viscoelastic nature. The current study aims to provide a modification to tire resistance by considering the power loss in a tire due to longitudinal slip. The modified tire resistance is comprised of rolling resistance and a newly introduced resistance caused by tire slip, called slip resistance. The physical model is chosen for parameters sensitivity study since the tractive force is described in this model via tangible physical parameters, e.g. tire tangential stiffness, coefficient of friction, and contact patch length.

Abstract The mechanical efficiency of the current continuously variable transmission (CVT) suffers from high pump loss induced by a high-pressure system. A novel wedge mechanism is designed into the CVT clamp actuation system to generate the majority of clamp force mechanically. Therefore, the hydraulic system can operate at a low-pressure level most of the time, and the pump loss is greatly reduced to improve the CVT’s mechanical efficiency. Through dynamic analysis and design optimization, 90% of clamp force is contributed by the wedge mechanism and the rest of the 10% is generated by a conventional hydraulic system. The optimal design is validated through dynamic modeling using Siemens Virtual.Lab software by simulating the wedge clamp force generation, ratio change dynamics, and system response under tip-in conditions. After that, we built prototype components that target 70% of the clamp force contributed by the wedge mechanism and tested them on a transmission dynamometer.

Abstract Rolling-resistance is leading the direction of numerous tire developments due to its significant effect on fuel consumption and CO2 emissions considering the vehicles in use globally. Many attempts were made to reduce rolling-resistance in vehicles, but with no or limited success due to tire complexity and trade-offs. This article investigates the concept of multiple chambers inside the tire as a potential alternative solution for reducing rolling-resistance. To accomplish that, novel multi-chamber designs were introduced and numerically simulated through finite-element (FE) modeling. The FE models were compared against a standard design as the baseline. The influences on rolling-resistance, grip, cornering, and mechanical comfort were studied. The multi-chambers tire model reduced rolling-resistance considerably with acceptable trade-offs. Independent air volumes isolating tread from sidewalls would maintain tire’s profile effectively.

Abstract To reduce fuel consumption and carbon dioxide (CO2) emissions from mobile air conditioning (A/C) systems, “U.S. Light-Duty Vehicle Greenhouse Gas Emissions and Corporate Average Fuel Economy Standards” identified solar/thermal technologies such as solar control glazings, solar reflective paint, and active and passive cabin ventilation in an off-cycle credit menu. National Renewable Energy Laboratory (NREL) researchers developed a sophisticated analysis process to calculate U.S. light-duty A/C fuel use that was used to assess the impact of these technologies, leveraging thermal and vehicle simulation analysis tools developed under previous U.S. Department of Energy projects. Representative U.S. light-duty driving behaviors and weighting factors including time-of-day of travel, trip duration, and time between trips were characterized and integrated into the analysis.

Abstract Power split in Fuel Cell Hybrid Electric Vehicles (FCHEVs) has been controlled using different strategies ranging from rule-based to optimal control. Dynamic Programming (DP) and Model Predictive Control (MPC) are two common optimal control strategies used in optimization of the power split in FCHEVs with a trade-off between global optimality of the solution and online implementation of the controller. This is due to the fact that DP that offers the global optimal solution requires the pre-known knowledge of the driving condition for the whole drive cycle, which makes the real-time implementation of the strategy more challenging. In this paper, both control strategies are developed and tested on a FC/battery vehicle model, and the results are compared in terms of total energy consumption. In addition, the effects of the MPC prediction horizon length on the controller performance are studied.

Abstract With increased consumer demand for fuel efficient vehicles as well as more stringent greenhouse gas regulations and/or Corporate Average Fuel Economy (CAFE) standards from governments around the globe, the automotive industry, including the OEM (Original Equipment Manufacturers) and suppliers, is working diligently to innovate in all areas of vehicle design. In addition to improving aerodynamics, enhancing internal combustion engines and transmission technologies, and developing alternative fuel vehicles, mass reduction has been identified as an important strategy in future vehicle development. In this article, the development, analysis, and experiment of multi-cornered structures are presented. To achieve mass reduction, two non-traditional multi-cornered structures, with twelve- and sixteen-cornered cross-sections, were developed separately by using computer simulations.

Abstract The pursuit of improved fuel economy through weight reduction, reduced manufacturing costs, and improved crash safety can result in increased compliance in automobile structures. However, with compliance comes an increased susceptibility to aerodynamic and vibratory loads. The hood in particular withstands considerable aerodynamic force at highway speeds, creating the potential for significant aeroelastic response that may adversely impact customer satisfaction and perception of vehicle quality. This work seeks an improved understanding in computational and experimental study of fluid-structure interactions between automobile hoods and the surrounding internal and external flow. Computational analysis was carried out using coupled CFD-FEM solvers with detailed models of the automobile topology and structural components. The experimental work consisted of wind tunnel tests using a full-scale production vehicle.

Abstract Sustainable practices are taking precedence across many industries, as evident from their shift towards the use of environmentally responsible materials, such as natural fiber-reinforced acrylated epoxidized soybean oil (NF-AESO). However, due to the lower reactivity of AESO, the curing reaction usually requires higher temperatures and longer curing time (e.g., 150°C for 6-12 h), thus making the entire process unsustainable. In this study, we demonstrate the potential power of photons towards manufacturing NF-AESO composites in a sustainable manner at room temperature (RT) within 10 min. Two photoinitiators, i.e., the 2,2-dimethoxy phenylacetophenone (DMPA) and 1-hydroxycyclohexyl phenyl ketone (HCPK), were evaluated and compared with the thermal initiator, i.e., tert-butyl perbenzoate (TBPB). Based on the mechanical performance of the AESOs, the photoinitiation system for NF-AESO was optimized.

Abstract Catalytic converters, a primary component in most automotive emissions control systems, do not function well until they are heated substantially above ambient temperature. As the primary energy for catalyst heating comes from engine exhaust gases, plug-in hybrid electric vehicles (PHEVs) that have the potential for short and infrequent use of their onboard engine may have limited energy available for catalytic converter heating. This article presents a comparison of multiple hybrid supervisory control strategies to determine the ability to avoid engine cold starts during a blended charge-depleting propulsion mode. Full vehicle and catalytic converter simulations are performed in parallel with engine dynamometer testing in order to examine catalyst temperature variations during the course of the US06 City drive cycle. Emissions and energy consumption (E&EC) calculations are also performed to determine the effective number of engine starts during the drive cycle.

Abstract Modern vehicles have incorporated numerous safety-focused advanced driver-assistance systems (ADAS) in the last decade including smart cruise control and object avoidance. In this article, we aim to go beyond using ADAS for safety and propose to use ADAS technology to enable predictive optimal energy management and improve vehicle fuel economy (FE). We combine ADAS sensor data with a previously developed prediction model, dynamic programming (DP) optimal energy management control, and a validated model of a 2010 Toyota Prius to explore FE. First, a unique ADAS detection scope is defined based on optimal vehicle control prediction aspects demonstrated to be relevant from the literature. Next, during real-world city and highway drive cycles in Denver, Colorado, a camera is used to record video footage of the vehicle environment and define ADAS detection ground truth. Then, various ADAS algorithms are combined, modified, and compared to the ground truth results.

Abstract Under contract to the EPA, Eastern Research Group analyzed light-duty vehicle OBD monitor readiness and diagnostic trouble codes (DTCs) using inspection and maintenance (I/M) data from four states. Results from roadside pullover emissions and OBD tests were also compared with same-vehicle I/M OBD results from one of the states. Analysis focused on the evaporative emissions control (evap) system, the catalytic converter (catalyst), the exhaust gas recirculation (EGR) system and the oxygen sensor and oxygen sensor heater (O2 system). Evap and catalyst monitors had similar overall readiness rates (90% to 95%), while the EGR and O2 systems had higher readiness rates (95% to 98%). Approximately 0.7% to 2.5% of inspection cycles with a “ready” evap monitor had at least one stored evap DTC, but DTC rates were under 1% for the catalyst and EGR systems, and under 1.1% for the O2 system, in the states with enforced OBD programs.

Abstract Fuel consumption is at an all-time high, with crude oil set to get depleted in the next two decades. Drag force is one of the major components responsible for decreasing mileage and thus increasing fuel consumption in vehicles. Using passive modifications such as spherical depressions on the body surface, aerodynamic drag experienced by passenger vehicles can be significantly reduced. Spherical depressions are designed to delay flow separation, following which the wake size is reduced, resulting in a decrease in drag force. In this study, computer-aided design (CAD) models of generalized lightweight vehicles are made with dimples at the sides of the car, having a diameter of 60 mm and a center-to-center distance of 90 mm. Several models are created having depression aspect ratios (ARs) of 2, 4, 6, and 8, and each model is simulated to velocities of 22 m/s, 24 m/s, 26 m/s, 28 m/s, and 30 m/s.

Abstract The principal issue in choosing an energy management strategy (EMS) for hybrid electric vehicles (HEVs) has been the way of determining the optimal share of electric energy in hybrid drive. In this article, a novel EMS is proposed that, along with maximum engine efficiency in the hybrid drive, can optimize the share of battery energy for the maximum efficiency of vehicle power train expanded with an imaginary power plant that, by delivering the electric energy to a grid, feeds the vehicle battery. It is proved that the expanded power train efficiency has the local maximum for a wide range of wheel power demand. The relation between the wheel power demand in hybrid drive, the share of battery energy, and the maximum efficiency of the expanded power train is conducted offline. Downloaded to the onboard control system, it enables the operation with the instantaneously optimal share of battery energy and the control system to operate with the low computational load.

Abstract In this study low temperature plasma technology was applied to expand auto-ignition operation region and control auto-ignition phasing of the homogeneous charge compression ignition (HCCI) combustion. The low temperature plasma igniter of a barrier discharge model (barrier discharge igniter (BDI)) with high-frequency voltage (15 kHz) was provided at the top center of the combustion chamber, and the auto-ignition characteristics of the HCCI combustion by the low temperature plasma assistance was investigated by using a single-cylinder gasoline engine. HCCI combustion with compression ratio of 15:1 was achieved by increasing the intake air temperature. The lean air-fuel (A/F) ratio limit and visualized auto-ignition combustion process on baseline HCCI without discharge assistance, spark-assisted HCCI, and BDI-assisted HCCI were compared.

Abstract The article describes the results achieved in developing a new diesel combustion system for passenger car application that, while capable of high power density, delivers excellent fuel economy through a combination of mechanical and thermodynamic efficiencies improvement. The project stemmed from the idea that, by leveraging the high fuel injection pressure of last generation common rail systems, it is possible to reduce the engine peak firing pressure (pfp) with great benefits on reciprocating and rotating components’ light-weighting and friction for high-speed light-duty engines, while keeping the power density at competitive levels. To this aim, an advanced injection system concept capable of injection pressure greater than 2500 bar was coupled to a prototype engine featuring newly developed combustion system. Then, the matching among these features has been thoroughly experimentally examined.

Abstract The wide application of Gasoline Direct Injection (GDI) engines and the increasingly stringent Particulate Matter (PM) and Particulate Number (PN) regulations make Gasoline Particulate Filters (GPFs) with high filtration efficiency and low pressure drop highly desirable. However, due to the specifics of GDI operation and GDI PM, the design of these filters is even more challenging as compared to their diesel counterparts. Computational Fluid Dynamics (CFD) studies have been shown to be an effective way to investigate filter performance. In particular, our previous two-dimensional (2D) CFD study explicated the pore size and pore-size distribution effects on GPF filtration efficiency and pressure drop. The “throat unit collector” model developed in this study furthers this work in order to characterize the GPF wall microstructure more precisely.

Abstract This study shows the development of low-temperature and high-temperature reactions in a gasoline-fuelled compression ignition (GCI) engine realizing partially premixed combustion for high efficiency and low emissions. The focus is how the ignition occurs during the low- to high-temperature reaction transition and how it varies due to single- and double-injection strategies. In an optically accessible, single-cylinder small-bore diesel engine equipped with a common-rail fuel injection system, planar laser-induced fluorescence (PLIF) imaging of formaldehyde (HCHO-PLIF), hydroxyl (OH-PLIF), and fuel (fuel-PLIF) has been performed. This was complemented with high-speed imaging of combustion luminosity and chemiluminescence imaging of cool flame and OH*.

Abstract In order to meet the worldwide increasingly stringent particulate matter (PM) and particulate number (PN) emission limits, the diesel particulate filter (DPF) is widely used today and has been considered to be an indispensable feature of modern diesel engines. To estimate the soot loading amount in the DPF accurately and in real-time is a key function of realizing systematic and efficient applications of diesel engines, as starting the thermal regeneration of DPF too early or too late will lead to either fuel economy penalty or system reliability issues. In this work, an open-loop and on-line approach to estimating the DPF soot loading on the basis of soot mass balance is developed and experimentally investigated, through establishing and combining prediction models of the NOx and soot emissions out of the engine and a model of the catalytic soot oxidation characteristics of passive regeneration in the DPF.