Natural gas technology company Westport Innovations has unveiled its newest proprietary technology, the first generation of an enhanced spark-ignited (ESI) natural gas system. This marks a change in the company’s philosophy of recent years, when it went down the route of direct gas injection and compression ignition on its natural gas engines for trucks.
Westport reckons the new design is cost competitive while providing similar levels of power, torque, and fuel economy to a larger diesel engine. Using 100 per cent dedicated natural gas as fuel, Westport’s new technology is said to optimise the combustion and thermal efficiencies of the engine by taking advantage of the positive properties of natural gas. The new Westport ESI combustion system is targeted at engines up to nine litres.
“As gasoline and diesel engines progress, it is critical that OEMs offer natural gas engines that retain their expected performance while providing the environmental and economic benefits of natural gas,” said Jack Keaton, Westport EVP of Global Spark Ignited Direct Injection. “Westport is taking its technology leadership to the next level by introducing a long term technology solution that allows improvements in engine performance and fuel economy, thus offering highly attractive operating costs and a low emissions profile. As the ESI technology continues to be developed, Westport will incorporate competitive performance upgrades to support the longevity of this system.”
As part of the new design, improvements in combustion and thermal management compared to typical spark-ignited natural gas engines are claimed to enhance the engine’s reliability. The new engines are showing up to a 10 per cent improvement in power and torque over the base diesel engine. This higher performance from a spark-ignited natural gas engine compared to a diesel engine potentially allows a four litre natural gas engine to replace a six litre diesel engine, at much lower mass.
Westport is claiming the design will provide up to 40 per cent brake thermal efficiency putting it in the same ballpark as a diesel, in terms of how much fuel is converted to useful energy. Typical spark ignited natural gas engines have approximately 25-30 per cent brake thermal efficiency and diesel engines have approximately 41 percent.
The new engine design is five per cent lighter than the comparable diesel engine. The port injection system provides better cylinder to cylinder control of the air fuel ratio. The new system is also designed to work with both liquefied and compressed natural gas.
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