On-board Measurements of City Buses with Hybrid Electric Powertrain, Conventional Diesel and LPG Engines

On-board measurements of fuel consumption and vehicle exhaust emissions of NO_x, HC, CO, CO₂, and PM are being conducted for three types of commercially available city buses in Guangzhou, China. The selected vehicles for this test include a diesel bus with Eaton hybrid electric powertrain, a conventional diesel bus with automated mechanical transmission (AMT), and a LPG powered city bus with manual transmission (MT). All of the tested vehicles were instrumented with on-board measurements. Horiba OBS-2200 was used for measuring NO_x, HC, and CO emissions; ELPI (Electrical Low Pressure Impactor) was used for PM measurement. The vehicles were tested at Hainan National Proving Ground in southern China.

Test data of fuel consumption and exhaust emissions were analyzed. The city bus with Eaton hybrid electric powertrain demonstrated more than 27% fuel consumption reduction over the conventional diesel powered bus, and over 68% over the LPG bus. The Eaton hybrid bus also showed 13% NO_x and 35% HC reductions compared with the conventional diesel powered bus and 29% NO_x and 99% HC reductions over the LPG bus when the buses are operated with air conditioning in an official China City Bus Cycle. The Eaton hybrid bus also showed 27% PM reduction compared with conventional diesel power bus; however, the PM emission level of Eaton hybrid bus was higher than the LPG powered bus.