Emission and Performance Comparison of the Natural Gas C-Gas Plus Engine in Heavy-Duty Trucks: Final Report

Abstract

Managed on-road prototype development at Viking Freight. Cummins Inc. Acted as primary subcontractor for this project (Product Development, Advanced Engineering, Service and Application teams participated); managed project for NREL. Cummins Westport Inc. (CWI) Joint venture between Cummins and Westport Innovations to develop, manufacture, and market natural gas engines; will produce the C-Gas Plus engine in the future. Southern California Gas Company Coordinated vehicle retrofit activities and Viking Freight support; installed Viking's in-house fueling station. Viking Freight Operated field test site for the two natural gas trucks and the two diesel control trucks. NGV Ecotrans Retrofitted natural gas vehicles used in study.

The GREET Model Expansion for Well-to-Wheels Analysis of Heavy-Duty Vehicles

“…This finding agrees with the WVU findings that lean-burn CNG transit buses with oxidation catalysts had about 84% less CO emissions compared to their diesel counterparts (Clark et al, 1999). Chassis dynamometer emission testing of MY 1997 diesel and MY 1994 CNG tractor trailers with oxidation catalysts showed that the CNG trucks had 90% less CO emissions compared to their diesel counterparts (Lyford-Pike, 2003).…”

“…For CNG engines, the HC mass primarily consists of CH 4 , with a limited portion being NMHCs. NMHC emissions from lean-burn CNG trucks with oxidation catalysts were found to be comparable to those from their diesel counterparts (Lyford-Pike, 2003). Tests of transit buses powered by 1997 Cummins 10-L lean-burn engines showed that about 95% of their HC emissions were CH 4 (Clark et al, 1997), which is typical for lean-burn NG vehicles (McKain et al, 2000).…”

“…Engine and exhaust control technologies used in CNG HDVs have advanced from leanburn, to lean-burn with an oxidation catalyst, to stoichiometric combustion with a TWC (Yoon et al, 2013) to meet these tighter emission standards. Chassis dynamometer emission testing showed that in CNG trucks with 1994 C-Gas Plus engines with oxidation catalysts, NO x emissions were significantly reduced, by 24-45% depending on duty cycles, and PM emissions were reduced by more than 90%, relative to their conventional diesel counterparts (Lyford-Pike, 2003). The Detroit Diesel Series 50G NG-powered buses using open-loop fueling controls produced, on average, 34% less NO x and 96% less PM on the Central Business District (CBD) cycle compared to Detroit Diesel Series 50 diesel-powered buses.…”

“…For lean-burn engines with oxidation catalysts, a duty-cycle-averaged tailpipe CH 4 emission factor of 7.7 g/mi was measured for heavy-duty trucks (Lyford-Pike, 2003). The tailpipe CH 4 emission factors for U.S. CNG transit buses with lean-burn engines tested by Yoon et al (2013) were 9.0 g/mi (standard error of 0.4 g/mi) for the CBD drive cycle, 6.4 g/mi (standard error of 0.2 g/mi) for the HD-UDDS drive cycle, and 3.0 g/mi (standard error of 0.3 g/mi) for a steady-state 45-mi-per-hour cruise test.…”

“…EPA's MOVES model suggests that there are no evaporative VOC emissions from NG transit buses, so we assumed the same for NG HDVs. a Lyford-Pike (2003). b Representing the lean-burn engine technology with oxidation catalyst, according to Clark et al (1999) and Lyford-Pike (2003).…”