Grantee Research Project Results

Final Report: Diesel Emissions Test Stand to Improve Selective Catalytic Reduction (SCR)

EPA Grant Number: SU835690
Title: Diesel Emissions Test Stand to Improve Selective Catalytic Reduction (SCR)
Investigators: Compere, Marc , Currier, Patrick , Boetcher, Sandra , Tang, Yan
Institution: Embry - Riddle Aeronautical University
EPA Project Officer: Page, Angela
Phase: I
Project Period: August 15, 2014 through August 14, 2015
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2014) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Challenge Area - Chemical Safety , P3 Awards , Sustainable and Healthy Communities

Objective:

The objective of our project was to use the diesel emission test stand as a physical emulator of a automotive diesel engine and exhaust system to develop models and advanced controls to reduce NOx emissions. Specifically, the intent is to develop advanced controls for Diesel hybrid vehicles. The goal was to get NOx emissions far below EPA regulations and as close to zero as possible without emitting harmful ammonia from the taipipe. With this emulator we characterized and implemented NOx and temperature sensors, and controlled the SCR actuator electronics to adjust the DEF fluid injection system. This NOx emissions reduction effort directly supports the EPA Clean Air Act (CAA) and Diesel Emissions Reduction Act (DERA) objectives. Reducing Diesel NOx emissions improves air quality, which contributes to improved human health, especially those susceptible to respiratory problems. It also supports the EPA drive for Prosperity and Planet sustainability by reducing the amount of acid rain that kills crops every year and by lowering total atmospheric NOx levels.

Summary/Accomplishments (Outputs/Outcomes):

Phase I focused on diesel emission test stand fabrication, load bank construction, custom electronics development, actuator control, NOx sensor interfaces, data logging, and temperature sensor calibration. A diesel generator, programmable load bank, and complete SCR system were mounted on a portable cart for quick development and outdoor Diesel emissions testing. NOx sensors were installed, interfaced through CANbus communications and calibrated with an emissions analyzer that measured temperature, NO and NO2 separately. Our industry partner, GFCS Corporaton provided access to the TESTO 350 portable emissions analyzer. A Simulink Test Manager software was developed for commanding the injector, pump, and heater actuators and reading the NOx sensors. An Arduino microcontroller with CANbus shield communicated to Simulink via bi-directional serial communications for both commanding actuators and logging sensor data. The three SCR heaters, the SCR pump, and SCR injector each required between 2A and 8A each for proper operation. Custom power electronics with high current MOSFETs were developed to accept signal-level inputs from an Arduino microcontroller to control the higher current actuators. The production NOx sensors were interfaced via an Arduino-based shield with Controllable Area Network (CAN) bus communication. Calibration from the production NOx sensors were independently verified with an emissions analyzer provided by the industry partner GFS Corporation. The recorded data from the NOx sensors showed a range of data that were between 3,200 ppm and 800 ppm depending on engine loading. This was an acceptable NOx emission range because it is similar to NOx output of a standard Diesel engine. In addition to the NOx sensors, the temperature sensors were calibrated to 650°C in a custom heater with type-K thermocouples. The calibrated temperature sensor measurements were also confirmed with the emissions analyzer’s exhaust gas temperature probe. Exhaust gas measurements of 355°C (670F) were recorded on the diesel test stand. The injector and pump were installed and tested for full functionality. DEF fluid line pressure is achieved to allow the injector to atomize the DEF fluid into the exhaust. The production pump, injector, and SCR catalyst and pipe were mounted and tested for fluid delivery into the running exhaust. The Simulink Test Manager software commands the injector and pump with simple on/off and PWM duty cycle commands. The tank heater, pump heater, and line heater all heat properly and can be commanded from the Test Manager Simulink software. With Matlab/Simulink as the Test Manager and logging software, test data are recorded and logged after each test. Testing of more than 1 hour was performed and post-processing revealed all ensors were logged properly for further analysys.

Conclusions:

The team at Embry-Riddle Aeronautical University has designed, built, and verified a physical emulator of an automotive diesel engine and exhaust system. Based on the results from the Phase I testing, the system is an excellent representation of a diesel automobile’s missions over standard EPA city and highway drive cycles. The small scale diesel engine and load bank can represent nearly any size diesel engine because of the normalized nature of parts-per-million (ppm) measurements. The ppm measurement normalizes exhaust gas measurements and is therefore independent of engine size. Temperature and production upstream and downstream NOx sensors were interfaced, calibrated, and their data logged in Matlab. The SCR injector, pump, and heaters were all made functional through the same Matlab/Simulink software interface. The test stand represents an optimal environment for advanced controls development for SCR-based NOx reduction. Emissions testing is straightforward, safe, and can be performed with constant or variable emissions commensurate with EPA city and highway drive cycles. The test stand provides straightforward access to the diesel engine, load bank, NOx and temperature sensors, SCR actuators and exhaust hardware. Testing is performed in a controlled, repeatable, and instrumented laboratory environment ideal for control system development. Based on these results, this diesel test stand is ideal for continued research and testing. It is an ideal foundation for continued NOx reduction research.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this project

Supplemental Keywords:

Diesel emissions, NOx, DPF, DOC, SCR, injector, catalyst

Relevant Websites:

Facebook Group for Clean Energy Club at Embry-Riddle,
Clean Energy Club at Embry-Riddle Aeronautical University Exit

P3 Phase II:

Diesel Emissions Test Stand to Improve Selective Catalytic Reduction  | 2016 Progress Report  | 2017 Progress Report  | Final Report