|The ELF CNG-DI, a joint entry between Isuzu and Westport, won two gold medals at the 2003 Michelin Challenge Bibendum.|
Westport Innovations and Isuzu have signed a new joint partnership and funding agreement for the application of Westport’s Compressed Natural Gas Direct Injection (CNG-DI) technologies on Isuzu engines and commercial vehicles.
The companies have been working together since 2000 on the technology, which provides up to 20% less greenhouse gas emissions (mainly carbon dioxide) than equivalent diesel engines, and improved fuel efficiency over current spark-ignited natural gas engines. (Earlier post.)
CNG-DI relies on late-cycle high-pressure injection of natural gas into the combustion chamber of an internal combustion engine in much the same fashion as diesel fuel. Just like in the diesel cycle, the natural gas is injected near the end of the compression stroke.
Natural gas has a higher ignition temperature than diesel (1,000° C vs. 500° C) and will not easily ignite at the temperatures and pressures in the combustion chamber of a normal diesel engine. To ignite the natural gas, a hot surface is used in the engine.
The hot surface within the ignition system is a ceramic-tipped glow plug operating between 1,200°C and 1,300°C. This is surrounded by a closed shield to ensure that ignition occurs in a robust manner, and that all the fuel jets are ignited. The ignition system is controlled to ensure that correct glow plug temperature is maintained at all times, providing optimum ignition performance and minimum glow plug temperature.
Use of natural gas reduces emissions, but the diesel-cycle diffusion combustion retains the power, torque, and efficiency of the diesel engine. The Westport catalyst-equipped, dedicated, monofuel natural gas engines have near-zero emissions of particulate matter.
Westport offers another technology approach to natural gas combustion in a diesel-cycle: High Pressure Direct Injection (HPDI). This system pre-injects a small amount of diesel that combusts under compression prior to injecting the natural gas—the diesel thus functions as a liquid spark plug. (Earlier post.)
HPDI is a bifuel system, requiring diesel and natural gas ; CNG-DI is a monofuel system.
Under the new agreement, Isuzu will provide Westport with C$1.5 million (US$1.3 million) of new funding through the calendar year 2006 to demonstrate up to 25% improved fuel economy over current spark-ignited CNG engines. Westport’s CNG-DI system on a 5-liter 4-cylinder Isuzu diesel engine will meet Japan’s Post New Long Term Exhaust Emissions standard for 2009. Work will be performed in Isuzu and Westport engine laboratories in Japan and Canada.
Isuzu and Westport have agreed to work towards completing an Intellectual Property Rights agreement (IPR) during the first quarter of 2006. Upon completion of the IPR, Westport and Isuzu engineering teams will work on design for manufacturing and cost optimization.
The Japanese Ministry of Land, Infrastructure and Transport (MLIT) is supporting the move towards CNG use in vehicles and away from diesel vehicles due to the reduction in emissions.
Japan currently has more than 24,000 natural gas vehicles and almost 300 refuelling stations. CNG in Japan currently retails at 63 to 76 yen per cubic meter; compared to gasoline at 124 yen per liter and diesel at 100 yen per liter. At these fuel prices, CNG is up to 54% less than gasoline and up to 38% less than diesel on an energy-equivalent basis.
Isuzu has had its most successful year ever for commercial CNG vehicles (CNGVs) in 2005 in Japan and plans to introduce CNGVs in China and several Southeast Asian countries.