Investigation of Thermal Management in a Diesel Exhaust System for Improved Emission Reduction Timothy Gardner Principal Engineer Tenneco, Inc.

Transcription

1 Investigation of Thermal Management in a Diesel Exhaust System for Improved Emission Reduction Timothy Gardner Principal Engineer Tenneco, Inc. 6 November 2017

2 Outline Background Objectives Model Description Model Validation Model Application Conclusions

3 Outline Background Objectives Model Description Model Validation Model Application Conclusions

4 Background The Challenge: Stringent Exhaust Emission Standards for Diesel Engines (CO, THC, NOx, PM) The Problem: Diesel Aftertreatment System components (DOC, DPF, SCR) require heat to reduce emissions. Diesel exhaust temperatures are too low for catalyst to lightoff, especially during cold-start. The Tenneco Solution: Apply a Thermal Unit (Burner) to provide additional heat!

5 Background Tenneco Thermal Unit PGM Free, Controlled heat supply Provides rapid emission system light-off Enables NOx emissions compliance for low temperature operations

6 Background

7 Outline Background Objectives Model Description Model Validation Model Application Conclusions

8 Objectives Investigate impact of a Thermal Unit on exhaust gas temperatures and emissions using GTSUITE: Location: Where to apply heat? Duration: How long to apply heat? Power: How much heat to apply?

9 Outline Background Objectives Model Description Model Validation Model Application Conclusions

10 Model Description: Thermal Unit Assumes 100% of injected fuel burns Combustion chamber modeled as a dual wall pipe w/air gap

11 Model Description Diesel Aftertreatment System Direct NH3 Inj. (SCR) Diesel Oxidation Catalyst (DOC) Diesel Particulate Filter (DPF) Selective Catalyst Reduction (SCR) Note: Adapted from GT Example Models

12 Outline Background Objectives Model Description Model Validation Model Application Conclusions

13 Model Validation (85 Steady-State pts) Test Set-up Thermocouple Locations

14 Outline Background Objectives Model Description Model Validation Model Application Conclusions

15 Model Application Apply GT Models to Investigate 5 Issues: Catalyst Light-Off: T50 Temperature Emissions: Secondary From TU Location: Where to apply heat? Duration: How long to apply heat? Power: How much heat to apply?

16 Model Application: Catalyst Light-Off Objective: Determine catalyst light-off temperatures in DOC & SCR Goals: Establish targets for evaluating TU impact Run Conditions: Temp Ramp: C Ramp Time: 600 sec TU Power: Off

17 Model Application: Secondary Emissions Objective: Determine best equiv. ratio (Φ) to operate TU Goals: Maximize Gas Temp. Minimize Sec. Emiss. Run Conditions: Eq. Ratio: 0.8 to 1.5 TU Power: 15 kw TU Duration: 300 sec

18 Model Application: TU Location Objective: Determine best location to apply TU Pre-DOC Goals: Faster Cat Light-Off Lower TP Emissions Pre-DPF Run Conditions: Equiv. Ratio: 0.9 TU Power: 15 kw TU Duration: 300 sec Pre-SCR

19 Model Application: TU Location Apply Pre-DOC Location for Best Cat Light-off!

20 Model Application: TU Location Apply Pre-DOC Location for Best Emission Conversion!

21 Model Application: TU Duration Objective: Determine how long to apply TU heat Goals: Lower Emissions Min. Fuel Consumption Run Conditions: TU Duration: s TU Power: 15 kw TU Location: Pre-DOC

22 Model Application: TU Duration Apply TU heat until SCR Substrate Temp reaches ~ 200 C

23 Model Application: TU Power Objective: Determine the best TU power input Goals: Faster Cat Light-Off Lower Emissions Min. Fuel Consumption Run Conditions: Equiv. Ratio: 0.9 TU Duration: 300 sec. TU Location: Pre-DOC

24 Model Application: TU Power Apply ~20 kw TU Power for Best Conversion Eff. & Fuel Consumption

25 Outline Background Objectives Model Description Model Validation Model Application Conclusions

26 Conclusions Based on the results of this study: 1. Thermal Unit Location Pre-DOC location is best for cat light-off & emissions 2. Thermal Unit Duration Apply TU heat until SCR temp stabilizes above 200 C for best NOx conversion & fuel consumption 3. Thermal Unit Power Apply ~20 kw TU power for optimum conversion efficiency and fuel consumption

27 Acknowledgements Special Thanks to the GTI Support Team: Jared Cromas Michael Pennisi Jon Brown Ryan Dudgeon

28 N o r t h A m e r i c a n G T - C o n f e r e n c e 28 THANK YOU! Q & A???