Background, 49 CFR 179.18 specifies that, to be qualified for use, a thermal protection system of a rail tank car has to pass a 30 min torch fire test. Fabricating the 1.22 x 1.22-m specimens needed to conduct a series of torch fire tests on different formulations of a novel thermal protection system is very expensive and presents major logistical challenges because of the quantity of material needed.…, Approach, The method that was developed in the IR&D project consists of the following components: A small-scale torch fire test that is used to obtain the thermal properties of the constituent materials of a new thermal protection system, needed for input into a numerical model of the full-scale torch fire test described in the CFR A validated numerical model of the small-scale torch fire test coupled…, Accomplishments, Reasonable agreement was obtained between the measured and calculated unexposed surface temperatures, which provides a proof-of-concept for the proposed method. However, the heat transfer model needs to be extended to three dimensions so that the non-uniformity of the thermal exposure, lateral heat transfer and heat losses at the edges of the specimen can be accounted for in the calculations.…
Type: IRD Synopsis
Background, There are several different computer-aided engineering (CAE) tools in the market to assist engineers in modeling vehicle and component-level performance under various driving conditions. However, few, if any, CAE tools allow a user to evaluate the thermal and mechanical performance while also considering a vehicle’s unique control strategy. The objective of this project was to use two CAE tools…, Approach, This effort was broken into several tasks focused to improve the performance model and, later, simulate the preliminary control strategy in conjunction with the performance model. The performance model was improved by parameterizing the mechanical and thermal characteristics of key powertrain components such as engine, battery and electric machine. With the mechanical and thermal modeling…, Accomplishments, The co-simulated CAE tools were setup to allow for easy parametrization of the models such that they can be adjusted to simulate several different architectures, hardware, and controls strategies. For this application, the battery pack, motor/inverter, on-board charger, and DC-DC converter was sized and selected. The model output indicated a P2 hybrid architecture was the most optimal solution…
Type: IRD Synopsis
Background, It is well known that NO and NO2 (NOx) are emitted from internal combustion engines as a byproduct of combustion, but the NO2:NOx ratio produced can vary depending on engine specifications and operating conditions. For example, stoichiometric gasoline engines produce nearly all NO, while diesel engines may produce varying NO2:NOx ratios depending on the given operating condition. Southwest…, Approach, In this program, a baseline HNO3 decomposition system was developed, and steady-state experiments were performed to determine the kinetic parameters associated with nitric acid decomposition reactions. The kinetic experiments conducted included the determination of the activation energy and reaction order associated with HNO3 decomposition. It was expected that the reaction rate would be first…, Accomplishments, It was determined that NO2:NOx control can be achieved by varying the nitrogen containing fuel flow rate and nitric acid flow rate. It was determined that total NOx control was approximately ± 20 ppm with a target NOx setpoint of 1000 ppm, and the gas phase HNO3 concentration was maintained below 3 ppm for all operating points. The maximum NO2:NOx ratio achieved was 90 %, and the minimum was 2%.…
Type: IRD Synopsis
Background, Since the mid-2000s, the global Automated Vehicle (AV) industry has invested more than $80 billion developing self-driving passenger, cargo, and industrial vehicles. Almost all of this research has assumed that other vehicles are manually driven. As a result, multi-vehicle maneuvers that ordinary human drivers trivially accomplish many times per day (such as highway merging, making unprotected…, Approach, The system is composed of a CV subsystem, a negotiation subsystem, and an autonomy subsystem. SwRI's novel negotiation subsystem uses the CV subsystem and a state machine to manage the status of all the vehicles involved in the maneuver, requesting and organizing the maneuver at a high level. The autonomy system of each vehicle is tasked with controlling the vehicle and providing information to…, Accomplishments, The three main possible merging scenarios were performed successfully on three of SwRI's autonomous vehicles in both phases (see attached demonstration video). The experiment was executed at SwRI’s test track and involved performing a multi-vehicle merge at approximately 25 mph. Depending on the arrival time of each vehicle, the merging vehicle would merge in front of, between, or behind the…
Type: IRD Synopsis
Background, Low-temperature combustion (LTC) concepts can demonstrate higher engine efficiencies than traditional pre-mixed spark-ignition combustion modes. Most LTC concepts, however, are extremely sensitive to slight changes in inlet temperature, pressure, or composition, posing challenges for practical application and transient control. One relatively new combustion strategy known as Spark Assisted…, Approach, An initial concept evaluation was carried out as a part of the prior Presidential Discretion IR project R8988. The study was limited to CFD modeling of the process in a PSA EB2 1.2 L engine with a modified compression ratio (CR) of 17:1 which demonstrated that there was a potential for engine efficiency improvement over the baseline operating with SACI + EGR. The CFD results confirmed the…, Accomplishments, The SCRE was first operated in a traditional SI combustion mode with EGR and H 2 to establish a baseline. The gross indicated thermal efficiency (gITE) results are shown in Figure 2. The results show that the engine was unstable at 33% EGR in absence of any H 2 . Upon introduction of H 2 , the engine stability and gITE could be extended further. The max gITE achieved during this testing was…
Type: IRD Synopsis
Background, There has been a rapid shift towards decarbonization of transportation; for light-duty applications it is feasible to use battery electric vehicles, but in heavy-duty applications the range limits and recharge times of batteries are impractical. Hydrogen fuel cells have been proposed as the alternative, but fuel cells are far more expensive than engines and have significant durability limits. To…, Approach, Computational fluid dynamics simulations of three compression-ignition concepts were carried out (see Figure 1): glow-plug assisted ignition, spark-assisted ignition, and diesel pilot ignition. These simulations were run using a baseline diesel engine combustion system and predicted indicated thermal efficiency of the combustion process and the emissions from combustion. Computational fluid…, Accomplishments, The simulation results showed promising results with similar or better indicated thermal efficiency than diesel combustion (see Figure 2) and similar emissions. These suggest the potential for a compression-ignited hydrogen engine to have similar fuel efficiency as a fuel cell vehicle. The emissions can easily be addressed using similar technology to a diesel engine. These results are being used…
Type: IRD Synopsis
Background, Thermal insulative coatings are an area of high interest in the diesel engine community; these coatings offer the potential to reduce heat losses through the piston to the engine oil and coolant. The energy can then serve to increase the engine power output and to increase exhaust temperatures, which is useful for aftertreatment thermal management and waste heat recovery. However, the design and…, Approach, An optical periscope was built to replace one of the exhaust valves on the engine. A yttrium aluminum garnet phosphor applied to the surface of the piston emits a temperature-dependent spectrum between 450-500 nm when illuminated with a 355 nm laser. Measurement of the spectral features from this phosphorescence allows for a direct measurement of the temperature of the piston surface. Optical…, Accomplishments, Spectral data have been acquired for a phosphor-coated steel piston. Correlation data to convert the spectral lines into a temperature measurement will be collected to complete the work and validate the experimental method and thermal models of the combustion-piston system.
Type: IRD Synopsis
Background, Simultaneous demands for improved efficiency, reduced emissions, and reduced weight have pushed many engine components (specifically cylinder heads) up against the limits of design, materials, and manufacturing capabilities. Additive manufacturing (AM) offers the potential of new design approaches to these issues. However, complex parts such as cylinder heads produced to date via AM have failed…, Approach, This project aimed to design an advanced cylinder head for ultra-high PCP capability by exploring two design paths: DOE and Topology Optimization. Each path first explored the structural requirements of the cylinder head, including combustion seal deflection and stress response to pressure loading via FEA. Cooling features were then evaluated though iterations of cooling flow CFD analysis. The…, Accomplishments, DOE simulations revealed different features were most influential in preventing cylinder head fire deck deflection when AM-based features are available compared using sand cast-only features in the design. A topology optimization path was introduced and refined that allowed input of several important cylinder head parameters such as component stress, fire deck deflection, and head bolt load. To…
Type: IRD Synopsis
Background, Regulated emissions output for medium-duty diesel engines are set to be significantly reduced over the coming decade. There are significant concerns that diesel engines will have difficulty meeting these future NOx and greenhouse gas (GHG) emission standards with reasonable aftertreatment costs. New technologies, such as cooled EGR, have recently been developed for stoichiometric SI engines which…, Approach, The SwRI high-efficiency medium-duty single-cylinder engine was operated on natural gas fuel with a first-generation (Gen 1) and second-generation (Gen 2) combustion system. The Gen 1 combustion system was had a compression ratio of 9:1, while the Gen 2 system had a compression ratio of 12:1. The cylinder head was also modified to adjust the tumble ratio and turbulent kinetic energy, as well as…, Accomplishments, The gross-efficiency of the second-generation combustion system increased almost 5% at some operating conditions. Gross efficiency achieved almost 45.5% as well. The increase of efficiency was mostly due to the increase compression ratio, but the changes to the cylinder head to optimize tumble ratio and flow performance also improved overall losses of the engine at some operating conditions as…
Type: IRD Synopsis
Background, Electric vehicles have been increasing in popularity in recent years. The drive units (motor, gear reduction, differential, and power electronics) within these electric vehicles typically use a petroleum-based fluid to lubricate the gear train and cool the electric motor and/or power electronics. There is a high likelihood that the fluid may encounter high-voltage components; therefore, the fluid…, Approach, The objective of this project was to develop a method to accurately and repeatably measure an electric drive unit’s electrical power consumption and mechanical power output to calculate overall drive unit efficiency while on a test stand so that it can be used to evaluate different drive unit fluids. The 150 kW Chevrolet Bolt drive unit was used as the device under test. The original equipment…, Accomplishments, The results from the testing were analyzed to determine the within-set, set-to-set and total variation produced by the developed test procedure. The target was to be able to detect an efficiency difference of ≤ 0.5% with 95% confidence. There were a few points that had too much variation to achieve this target. These points were at relatively low power where the signal-to-noise ratio of the…
Type: IRD Synopsis
