A four-stroke gas engine developed in China is ready to be put into service, according to enginebuilder and designer Shanghai Marine Diesel Engine Research Institute (SMDERI).
The company’s eight-cylinder M23G engine deploys the lean-burn, Otto cycle method of low-pressure gas injection. It is notable for its ignition process, initiated by a spark plug in a pre-combustion chamber that features a separate gas supply to the engine cylinder. The air-to-fuel ratio in the cylinder is controlled by a throttle which adjusts the air inlet and exhaust wastegate.
The M23G meets IMO Tier III NOx emission limits without after-treatment. The eight-cylinder version, with a bore of 230mm and a stroke of 320mm, boasts a power output of 1,600kW at 1,000 rpm.
The engine, which has been in development since 2015, has accumulated 600 hours on the testbed, while a prototype based on SMDERI’s 6CS21 diesel engine has been installed on a tugboat and has been operated for several hundred hours. China Classification Society has issued a type approval certificate for the new engine.
“The design, production and test phase are complete and the engine has already been well developed,” said Li Xiang of SMDERI’s new technology department. “Based on the successful application of the 6CS21 diesel engine, we believe that the M23G will be accepted by the market in the near future.”
SMDERI’s gas engine development programme follows the introduction of the CS21 medium-speed diesel engine range in 2011. The company also co-designed the Auxpac 16 generating set with Wärtsilä. Described as the world’s smallest generating set, it delivers 735kW through six 160mm-bore cylinders.