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Technical Paper

Will Your Battery Survive a World With Fast Chargers?

Fast charging is attractive to battery electric vehicle (BEV) drivers for its ability to enable long-distance travel and to quickly recharge depleted batteries on short notice. However, such aggressive charging and the sustained vehicle operation that results could lead to excessive battery temperatures and degradation. Properly assessing the consequences of fast charging requires accounting for disparate cycling, heating, and aging of individual cells in large BEV packs when subjected to realistic travel patterns, usage of fast chargers, and climates over long durations (i.e., years). The U.S. Department of Energy's Vehicle Technologies Office has supported the National Renewable Energy Laboratory's development of BLAST-V-the Battery Lifetime Analysis and Simulation Tool for Vehicles-to create a tool capable of accounting for all of these factors. We present on the findings of applying this tool to realistic fast charge scenarios.
Technical Paper

Using a Sweating Manikin, Controlled by a Human Physiological Model, to Evaluate Liquid Cooling Garments

An Advanced Automotive Manikin (ADAM), is used to evaluate liquid cooling garments (LCG) for advanced space suits for extravehicular applications and launch and entry suits. The manikin is controlled by a finite-element physiological model of the human thermoregulatory system. ADAM's thermal response to a baseline LCG was measured.The local effectiveness of the LCG was determined. These new thermal comfort tools permit detailed, repeatable measurements and evaluation of LCGs. Results can extend to other personal protective clothing including HAZMAT suits, nuclear/biological/ chemical protective suits, fire protection suits, etc.
Technical Paper

Use of a Thermal Manikin to Evaluate Human Thermoregulatory Responses in Transient, Non-Uniform, Thermal Environments

People who wear protective uniforms that inhibit evaporation of sweat can experience reduced productivity and even health risks when their bodies cannot cool themselves. This paper describes a new sweating manikin and a numerical model of the human thermoregulatory system that evaluates the thermal response of an individual to transient, non-uniform thermal environments. The physiological model of the human thermoregulatory system controls a thermal manikin, resulting in surface temperature distributions representative of the human body. For example, surface temperatures of the extremities are cooler than those of the torso and head. The manikin contains batteries, a water reservoir, and wireless communications and controls that enable it to operate as long as 2 hours without external connections. The manikin has 120 separately controlled heating and sweating zones that result in high resolution for surface temperature, heat flux, and sweating control.
Technical Paper

Total Thermal Management of Battery Electric Vehicles (BEVs)

The key hurdles to achieving wide consumer acceptance of battery electric vehicles (BEVs) are weather-dependent drive range, higher cost, and limited battery life. These translate into a strong need to reduce a significant energy drain and resulting drive range loss due to auxiliary electrical loads the predominant of which is the cabin thermal management load. Studies have shown that thermal sub-system loads can reduce the drive range by as much as 45% under ambient temperatures below −10 °C. Often, cabin heating relies purely on positive temperature coefficient (PTC) resistive heating, contributing to a significant range loss. Reducing this range loss may improve consumer acceptance of BEVs. The authors present a unified thermal management system (UTEMPRA) that satisfies diverse thermal and design needs of the auxiliary loads in BEVs.
Technical Paper

Thermal Load Reduction System Development in a Hyundai Sonata PHEV

Increased market penetration of electric drive vehicles (EDVs) requires overcoming a number of hurdles, including limited vehicle range and the elevated cost in comparison to conventional vehicles. Climate control loads have a significant impact on range, cutting it by over 50% in both cooling and heating conditions. To minimize the impact of climate control on EDV range, the National Renewable Energy Laboratory has partnered with Hyundai America and key industry partners to quantify the performance of thermal load reduction technologies on a Hyundai Sonata plug-in hybrid electric vehicle. Technologies that impact vehicle cabin heating in cold weather conditions and cabin cooling in warm weather conditions were evaluated. Tests included thermal transient and steady-state periods for all technologies, including the development of a new test methodology to evaluate the performance of occupant thermal conditioning.
Technical Paper

Thermal Evaluation of Toyota Prius Battery Pack

As part of a U.S. Department of Energy supported study, the National Renewable Energy Laboratory has benchmarked a Toyota Prius hybrid electric vehicle from three aspects: system analysis, auxiliary loads, and battery pack thermal performance. This paper focuses on the testing of the battery back out of the vehicle. More recent in-vehicle dynamometer tests have confirmed these out-of-vehicle tests. Our purpose was to understand how the batteries were packaged and performed from a thermal perspective. The Prius NiMH battery pack was tested at various temperatures (0°C, 25°C, and 40°C) and under driving cycles (HWFET, FTP, and US06). The airflow through the pack was also analyzed. Overall, we found that the U.S. Prius battery pack thermal management system incorporates interesting features and performs well under tested conditions.
Technical Paper

The Impact of Metal-free Solar Reflective Film on Vehicle Climate Control

The air-conditioning system can significantly impact the fuel economy and tailpipe emissions of automobiles. If the peak soak temperature of the passenger compartment can be reduced, the air-conditioner compressor can potentially be downsized while maintaining human thermal comfort. Solar reflective film is one way to reduce the peak soak temperature by reducing the solar heat gain into the passenger compartment. A 3M non-metallic solar reflective film (SRF) was tested in two minivans and two sport utility vehicles (SUV). The peak soak temperature was reduced resulting in a quicker cooldown. Using these data, a reduction in air-conditioner size was estimated and the fuel economy and tailpipe emissions were predicted.
Technical Paper

The Department of Energy's Hydrogen Safety, Codes, and Standards Program: Status Report on the National Templates1

A key to the success of the national hydrogen and fuel cell codes and standards developments efforts to date was the creation and implementation of national templates through which the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory (NREL), and the major standards development organizations (SDOs) and model code organizations coordinate the preparation of critical standards and codes for hydrogen and fuel cell technologies and applications and maintain a coordinated national agenda for hydrogen and fuel cell codes and standards
Technical Paper

The DOE/NREL Environmental Science Program

This paper summarizes the several of the studies in the Environmental Science Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of the Environmental Science Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based fuels and alternative transportation fuels from mobile sources. The Program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. Each project in the Program is designed to address policy-relevant objectives. Current projects in the Environmental Science Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements; emission inventory development/improvement; ambient impacts, including health effects.
Technical Paper

The DOE/NREL Environmental Science & Health Effects Program - An Overview

This paper summarizes current work in the Environmental Science & Health Effects (ES&HE) Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. The goal of the ES&HE Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based and alternative transportation fuels. Each project in the program is designed to address policy-relevant objectives. Studies in the ES&HE Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements, emission inventory development/improvement; and ambient impacts, including health effects.
Technical Paper

Test Results and Modeling of the Honda Insight using ADVISOR

The National Renewable Energy Laboratory (NREL) has conducted a series of chassis dynamometer and road tests on the 2000 model-year Honda Insight. This paper will focus on results from the testing, how the results have been applied to NREL's Advanced Vehicle Simulator (ADVISOR), and how test results compare to the model predictions and published data. The chassis dynamometer testing included the FTP-75 emissions certification test procedure, highway fuel economy test, US06 aggressive driving cycle conducted at 0°C, 20°C, and 40°C, and the SC03 test performed at 35°C with the air conditioning on and with the air conditioning off. Data collection included bag and continuously sampled emissions (for the chassis tests), engine and vehicle operating parameters, battery cell temperatures and voltages, motor and auxiliary currents, and cabin temperatures.
Technical Paper

Tensile and Fatigue Behaviors of Two Thermoplastics Including Strain Rate, Temperature, and Mean Stress Effects

An experimental investigation was conducted to evaluate tensile and fatigue behaviors of two thermoplastics, a neat impact polypropylene and a mineral and elastomer reinforced polyolefin. Tensile tests were performed at various strain rates at room, −40°C, and 85°C temperatures with specimens cut parallel and perpendicular to the mold flow direction. Tensile properties were determined from these tests and mathematical relations were developed to represent tensile properties as a function of strain rate and temperature. For fatigue behavior, the effects considered include mold flow direction, mean stress, and temperature. Tension-compression as well as tension-tension load-controlled fatigue tests were performed at room temperature, −40°C and 85°C. The effect of mean stress was modeled using the Walker mean stress model and a simple model with a mean stress sensitivity factor.
Technical Paper

Temperature Control of Water with Heating, Cooling and Mixing in a Process with Recycle Loop

A hot and cold water mixing process with a steam condenser and a chilled water heat exchanger is set up for an engine EGR fouling test. The test rig has water recycled in the loop of a pump, heat exchangers, a three-way mixing valve, and a test EGR unit. The target unit temperature is controlled by a heating, cooling and mixing process with individual valves regulating the flow-rate of saturated steam, chilled water and mixing ratio. The challenges in control design are the dead-time, interaction, nonlinearity and multivariable characteristics of heat exchangers, plus the flow recycle in the system. A systems method is applied to extract a simple linear model for control design. The method avoids the nonlinearity and interaction among different temperatures at inlet, outlet and flow-rate. The test data proves the effectiveness of systems analysis and modeling methodology. As a result, the first-order linear model facilitates the controller design.
Technical Paper

Technology Improvement Pathways to Cost-effective Vehicle Electrification

Electrifying transportation can reduce or eliminate dependence on foreign fuels, emission of green house gases, and emission of pollutants. One challenge is finding a pathway for vehicles that gains wide market acceptance to achieve a meaningful benefit. This paper evaluates several approaches aimed at making plug-in electric vehicles (EV) and plug-in hybrid electric vehicles (PHEVs) cost-effective including opportunity charging, replacing the battery over the vehicle life, improving battery life, reducing battery cost, and providing electric power directly to the vehicle during a portion of its travel. Many combinations of PHEV electric range and battery power are included. For each case, the model accounts for battery cycle life and the national distribution of driving distances to size the battery optimally. Using the current estimates of battery life and cost, only the dynamically plugged-in pathway was cost-effective to the consumer.
Technical Paper

Technological Comparison for Dual Phase and Advanced High Strength Low Alloy Steels Regarding Weldability and Mechanical Properties

This paper presents a technological comparison of weldability and mechanical properties between a dual phase steel (DP) and an advanced high strength low alloy steel (AHSLA) used for automotive structural parts in order to demonstrate some unclear characteristics of each. Samples were spot welded and had their hardness and microstructure analyzed, also a shear test was applied on the weld button area. The edge stretchability was analyzed using hole expansion tests and tensile tests to determine the tensile and yield strength, anisotropic coefficients and total elongation. Data were used to estimate crash energy absorption. The results showed an AHSLA steel with higher than typical ductility. Finally, while DP showed improved stretchability, it was also concluded that such AHSLA could perform better bendability, drawability, flangeability and weldability.
Journal Article

Subsystem Rollover Tests for the Evaluation of ATD Kinematics and Restraints

The development of a repeatable dynamic rollover test methodology with meaningful occupant protection performance objectives has been a longstanding and unmet challenge. Numerous studies have identified the random and chaotic nature of rollover crashes, and the difficulty associated with simulating these events in a laboratory setting. Previous work addressed vehicle level testing attempting to simulate an entire rollover event but it was determined that this test methodology could not be used for development of occupant protection restraint performance objectives due to the unpredictable behavior of the vehicle during the entire rollover event. More recent efforts have focused on subsystem tests that simulate distinct phases of a rollover event, up to and including the first roof-to-ground impact.
Journal Article

Strain Field Measurement in the Vicinity of Ductile Rupture from Digital Image Correlation

A methodology that enables two-dimensional strain field measurement in the vicinity of ductile rupture is described. Fully martensitic steel coupons were strained to fracture using a miniature tensile stage with custom data and image acquisition systems. Rupture initiated near the center of each coupon and progressed slowly toward the gage section edges. A state-of-the-art digital image correlation technique was used to compute the true strain field before rupture initiation and ahead of the resulting propagating macroscopic crack before final fracture occurred. True strains of the order of 95% were measured ahead of the crack at later stages of deformation.
Technical Paper

Solar Heat Load on the Vehicle Occupants

Vehicle occupants, unlike building occupants, are exposed to continuously varying, non-uniform solar heat load. Automotive manufacturers use photovoltaic cells based solar sensor to measure intensity and direction of the direct-beam solar radiation. Use of the time of the day and the position - latitude and longitude - of a vehicle is also common to calculate direction of the direct-beam solar radiation. Two angles - azimuth and elevation - are used to completely define the direction of solar radiation with respect to the vehicle coordinate system. Although the use of solar sensor is common in today’s vehicles, the solar heat load on the occupants, because of their exposure to the direct-beam solar radiation remains the area of in-car subjective evaluation and tuning. Since the solar rays travel in parallel paths, application of the ray tracing method to determine solar insolation of the vehicle occupants is possible.
Technical Paper

Sleeper Cab Climate Control Load Reduction for Long-Haul Truck Rest Period Idling

Annual fuel use for long-haul truck rest period idling is estimated at 667 million gallons in the United States. The U.S. Department of Energy's National Renewable Energy Laboratory's CoolCab project aims to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by working closely with industry to design efficient long-haul truck climate control systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In order for candidate idle reduction technologies to be implemented at the original equipment manufacturer and fleet level, their effectiveness must be quantified. To address this need, a number of promising candidate technologies were evaluated through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads.
Journal Article

Simulation Fidelity Improvement of H350 Lower Tibia Indices

Finite element dummy models have been more and more widely applied in virtual development of occupant protection systems across the automotive industry due to their predictive capabilities. H350 dyna dummy model [1] is a finite element representation of the Hybrid III male dummy [2], which is designed to represent the average of the United States adult male population. Lower extremity injuries continue to occur in front crash accidents despite increasing improvement of vehicle crashworthiness and occupant restraint system. It is therefore desirable to predict lower tibia injury numbers in front occupant simulations. Though lower tibia loading/index predictions are not studied as much as the FMVSS 208 regulated injury numbers, the tibia indices are injury criteria that need to be assessed during IIHS and Euro NCAP frontal offset occupant simulations. However during front crash simulations, it is very difficult to achieve good correlations or predictions of lower tibia loadings.