(3-04) Development of the Lean Burn Miller Cycle Gas Engine((AF-2)Alternative Fuels 2-Gas Engines)

概要

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Cogeneration systems, using natural gas engine, have been increased because of low NOx emission and low particulate emission. But recently electric power company have been reduced the price of electric power, so it is necessary to increase power generation efficiency of gas engine. To improve thermal efficiency of gas engine, we applied the Miller cycle to the lean burn gas engine. And we improved combustion system and turbocharger for Miller cycle. In order to decide compression ratio and expansion ratio, we used a cycle simulation and a single cylinder test engine. Compression ratio was set to 11 and expansion ratio was set to 15. Inlet swirl ratio was reduced to prevent knocking. In case of low swirl, the combustion rate was decreased, so ignition timing could be advanced. In case of Miller cycle, high boost pressure is necessary to keep engine power. So we developed the high pressure ratio and high efficiency turbocharger. And high durability type spark plug and electrical fuel supply system were applied for high reliability. Finally thermal efficiency of Miller cycle gas engine reached to 42%(Power generation efficiency is 40%). We confirmed that 42% of thermal efficiency during 4000Hr. We have already put 280kW cogeneration package in the market.
一般社団法人日本機械学会の論文
2001-07-01