Sandesh Rao’s research while affiliated with Southwest Research Institute and other places

div class="section abstract"> The US EPA and the California Air Resources Board (CARB) require electric vehicle range to be determined according to the Society of Automotive Engineers (SAE) surface vehicle recommended practice J1634 - Battery Electric Vehicle Energy Consumption and Range Test Procedure. In the 2021 revision of the SAE J1634, the Short Multi-Cycle Test (SMCT) was introduced. The proposed testing protocol eases the chassis dynamometer test burden by performing a 2.1-hour drive cycle on the dynamometer, followed by discharging the remaining battery energy into a battery cycler to determine the Useable Battery Energy (UBE). Opting for a cycler-based discharge is financially advantageous due to the extended operating time required to fully deplete a 70-100kWh battery commonly found in Battery Electric Vehicles (BEVs). This paper provides a review of the communication protocols enabling V2X (Vehicle to X, where X can be grid, vehicle, building, etc.) power transfer and the tools required to initiate, control, and terminate the vehicle testing procedure as per SAE J1634. The primary focus is on the series of ISO 15118 standards for road vehicles - vehicle to grid communication interface and SAE J2847/2 (Surface vehicle standard for communication between plug-in vehicles and off-board DC chargers). </div

div class="section abstract"> This work is a part of medium-duty Low NO _x technology development project with a focus on evaluating a combination of engine and advanced aftertreatment for 0.02 g/bhp-hr NO _x regulation proposed by CARB (California air resource board). In this project, a control oriented chemical kinetics model of SCR (Selective catalytic reduction) was used in the aftertreatment controller that is susceptible to performance degradation due to hydrothermal and chemical aging. This paper focuses on modeling the NO _x conversion and NH3 storage characteristics using a controls oriented SCR plant model which is further used for a model-based urea dosing scheme. A set of steady state reactor tests were used to calibrate the SCR performance at degreened, hydrothermal only and hydrothermal + chemical aging conditions and also to determine inhibition factors related to aging. The resultant model is capable of simulating SCR performance deterioration such as a reduction in NO _x conversion and NH3 storage. A non-linear aging profile was observed for Lo-SCR and downstream SCR showing a change in the NO _x conversion in the aged system when compared to a degreened system. Upon chemical aging further deterioration of low temperature performance was observed. This aging phenomenon impacts the dosing control strategy of the system. The results on controller performance for a set of Heavy Duty Federal Test Protocol(FTP), Ramp Modal Cycle (RMC), and Low Load Cycle (LLC) are presented. </div

div class="section abstract"> Eco-driving algorithms enabled by Vehicle to Everything (V2X) communications in Connected and Automated Vehicles (CAVs) can improve fuel economy by generating an energy-efficient velocity trajectory for vehicles to follow in real time. Southwest Research Institute (SwRI) demonstrated a 7% reduction in energy consumption for fully loaded class 8 trucks using SwRI’s eco-driving algorithms. However, the impact of these schemes on vehicle emissions is not well understood. This paper details the effort of using data from SwRI’s on-road vehicle tests to measure and evaluate how eco-driving could impact emissions. Two engine and aftertreatment configurations were evaluated: a production system that meets current NO_X standards and a system with advanced aftertreatment and engine technologies designed to meet low NO_X 2031+ emissions standards. For the production system, eco-driving on an urban cycle resulted in a CO₂ reduction of 8.4% but an increase of 18% in brake specific NO_X over the baseline cycle. With the low NO_X system, eco-driving achieved a similar reduction in CO₂. NO_X emissions increased 108% over the baseline but remained below the low NO_X standard. The eco-driving cycles generated lower exhaust temperatures than the baseline cycles, which inhibited SCR catalyst performance and increased tailpipe NO_X. Conversely, a port drayage cycle with eco-driving showed improvements in both CO₂ and NO_X emissions over the baseline. The results demonstrate that eco-driving algorithms can be a technological enabler to meet current and potential future emissions targets for heavy-duty applications. </div

div class="section abstract"> Trained human raters have been used by organizations such as the Coordinating Research Council (CRC) to assess the vehicle driveability performance effect of fuel volatility. CRC conducts workshops to test fuel effects and their impact on vehicle driveability. CRC commissioned Southwest Research Institute (SwRI) to develop a “Trick Car” vehicle that could trigger malfunctions on-demand that mimic driveability events. This vehicle has been used to train novice personnel on the CRC Driveability Procedure E-28-94. While largely effective, even well-trained human raters can be inconsistent with other raters. Further, CRC rater workshop programs used to train and calibrate raters are infrequent, and there are a limited number of available trained raters. The goal of this program was to augment or substitute human raters with an electronic driveability sensing system. The Automated Driveability Rating System (ADRS) was developed for Light Duty (LD) vehicles and can identify and rate fuel-related driveability events including hesitation, stumble, surge, stall, and idle quality at trace, moderate, and heavy severities. The portable system uses sensors such as accelerometers, and interfaces with a vehicle to gather and process an array of information. Overall, ADRS performance ranged from somewhat less accurate to significantly better than trained human raters depending on the event type and severity. For light and moderate vehicle throttle tests, detection of stumble, surge, and hesitation events by the ADRS was close to or better than 90%, while idle quality accuracy was 80%. These results are better when compared to the performance of trained raters. Additional effort in refining the calibration and improving event identification could enhance performance even further, and the system could be applied more broadly in rating ride quality and vehicle behavior. </div

div class="section abstract"> Despite considerable progress towards clean air in previous decades, parts of the United States continue to struggle with the challenge of meeting the ambient air quality targets for smog-forming ozone mandated by the U.S. EPA, with some of the most significant challenges being seen in California. These continuing issues have highlighted the need for further reductions in emissions of NO_X, which is a precursor for ozone formation, from a number of key sectors including the commercial vehicle sector. In response, the California Air Resources Board (CARB) embarked on a regulatory effort culminating in the adoption of the California Heavy-Duty Low NO_X Omnibus regulation.[ 1 ] This regulatory effort was supported by a series of technical programs conducted at Southwest Research Institute (SwRI). These programs were aimed at demonstrating technologies that could enable heavy-duty on-highway engines to reach tailpipe NO_X levels up to 90% below the current standards, which were implemented in 2010, while maintaining a path towards compliance with current heavy-duty Phase 2 GHG standards. These efforts culminated in the Stage 3 Low NO_X program, the results of which have been documented in previous publications. In parallel with the completion of the Stage 3 technical effort, EPA began an effort to promulgate a national heavy-duty low NO_X regulation, with the goal of completing the regulation in 2022 to support a 2027 model year implementation.[ 2 , 3 ] As part of that regulatory effort, EPA leveraged the test platform that was developed under the Stage 3 program to continue investigation of Low NO_X technology capabilities and limitations. The emission control system was upgraded in several ways, and a number of topics were examined that expanded the scope of the evaluation. These included investigation of system performance under a variety of field duty cycles, examination of extended useful life out to 800,000 miles, the impact of low ambient temperatures on performance, and others. The performance of the updated system, and the results of the wider system investigations are summarized in this paper. </div

div class="section abstract"> Typical two-site storage-based SCR plant models in literature consider NH₃ stored in the first site to participate in NH₃ storage, NO _x conversion and second site to only participate in NH₃ storage passively. This paper focuses on quantifying the impact of stored NH₃ in the second site on the overall NO _x conversion for an ultra-low NO _x system due to intra site NH₃ mass transfer. Accounting for this intra site mass transfer leads to better prediction of SCR out NH₃ thus ensuring compliance with NH₃ coverage targets and improved dosing characteristics of the controller that is critical to achieving ultra-low NO _x standard. The stored NH₃ in the second site undergoes mass transfer to the first site during temperature ramps encountered in a transient cycle that leads to increased NO _x conversion in conditions where the dosing is switched off. The resultant NH₃ coverage fraction prediction is critical in dosing control of SCR. This phenomenon is evaluated and quantified with different aging conditions, where the increased second site storage and reduced standard SCR activity due to hydrothermal aging leads to further increase in the reported phenomena. Although this phenomenon was observed for both light-off SCR (Lo-SCR) and downstream SCR based on analysis of the data, the impact on Lo-SCR performance was found to be higher compared to the downstream system due to the transient thermal conditions and higher temperatures experienced by the Lo-SCR system. This mass transfer mechanism also plays a role in determining NH₃ slip characteristics of Lo-SCR for real world conditions where the gradual transfer of NH3 in the axial direction leads to NH3 slip. This phenomenon is demonstrated using experimental data collected on a production engine for a set of HFTP, CFTP, RMC and LLC cycles </div

div class="section abstract"> Despite considerable progress over the last several decades, California continues to face some of the most significant air quality problems in the United States. These continued issues highlight the need for further mobile source NO_X reductions to help California and other areas meet ambient air quality targets mandated by the U.S. EPA. Beginning in 2014, the California Air Resources Board (CARB) launched a program aimed at demonstrating technologies that could enable heavy-duty on-highway engines to reach tailpipe NO_X levels up to 90% below the current standards, which were implemented in 2010. At the same time, mandated improvements to greenhouse gas emissions (GHG) require that these NO_X reductions be achieved without sacrificing fuel consumption and increasing GHG emissions. The CARB demonstration program has progressed through several stages since it was initiated, and the Stage 3 Low NO_X program completed in 2020 represents the culmination of these technology demonstration efforts. This effort, using a 2017 production diesel engine as a baseline, demonstrated a combination of technologies that enabled Low NO_X emission levels near the 90% reduction target, while at the same time maintaining GHG emission rates at the same levels as the base engine. Previous publications have gone into detail regarding individual elements of the Stage 3 technology package. This paper will present a summary of the final configuration and final results of the Stage 3 program, including results for the fully aged aftertreatment system after the equivalent of 435,000 miles of operation. The performance of the final test article will be shown over a variety of both regulatory duty cycles and other off-cycle operations. The final fuel consumption and GHG performance of the system will also be described based on the benchmarking methods specified by EPA in the Phase 2 GHG standards. </div