Mitsubishi Heavy Industries (MHI) is moving towards the final verification of a new gas engine that it claims will be one of the most efficient engines of its type in the world.
The new Mach II-SI engine represents a significant step forward in efficiency for engines of its class, says MHI. The engine has already undergone performance testing and has now progressed to the next stage, which will include durability testing and final verification of its reliability.
The Mach SI-II is based on MHI’s existing Mach-30G gas engine, but uses a spark ignition (SI) system rather than a micro-pilot ignition. This, and other improvements mean that the new unit can achieve an efficiency of 66.1 per cent – combining power generation and heat recovery via steam – the world’s highest level among 6000 kW-class engines. MHI also says that it has improved electrical conversion efficiency by one percentage point.
The enhanced efficiency means that the engine is expected to make a significant contribution towards the increasing need for CO2 emission reduction, according to the Japanese firm, which tested the unit at its Yokohama Machinery works last year.
To enhance overall efficiency, MHI focussed on enhanced heat recovery in steam generation and effective utilisation of exhaust gas energy. It has also shortened the lead-time to full load by 50 per cent, enhancing the engine’s load-following capability.
The increase in power generation efficiency has been achieved through a redesign of the combustion chamber, including the cylinder cover and piston. By optimising formulation of the fuel-air mixture, as well as modifying the pre-chamber’s shape and fuel-air mixture ratio, MHI has raised combustion efficiency and reduced thermal loss.
Some of the technology developed for the engine is based upon results obtained from a joint development project between MHI, the Japan Gas Association and the New Energy and Industrial Technology Development Organization (NEDO), says MHI. Some of the new technologies will be applied to existing Mach engines.
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