The first frame size in the new A100-L series of high-pressure turbochargers for low-speed, two-stroke engines has been released for sale by ABB Turbocharging. Labeled the A175-L, the new turbocharger is designed to give pressure ratios of 4.7 and above and volume flow of 25 m3/sec. The company said its target market is advanced low-speed, two-stroke diesel engines needing turbochargers with pressure ratios above 4.0 and featuring the highest turbocharging efficiencies.
Already, two A175-L turbochargers fitted with ABB Turbocharging’s variable turbine technology (VTG) are operational. One is a retrofit on the 1068 TEU container vessel Alexander Maersk, a demonstrator in the “Green Ship of the Future” project, which targets the development of technologies for reducing emissions from ships and under the auspices of the Government of Denmark, with ABB Turbocharging as a partner.
Klaus Fusstetter, ABB Turbocharging application engineer said, “First, due to its very high efficiency, this state-of-the-art turbocharger gives significant improvements in fuel consumption and the formation of oxides of nitrogen (NOx) compared to the older unit it has replaced. Second, the inclusion of VTG technology allows close matching of the quantity of charge-air reaching the combustion chamber to the amount of fuel injected. And, third, VTG is an essential part of the exhaust gas recirculation system fitted on the Alexander Maersk’s main engine to significantly reduce NOx.”
In ABB Turbocharging’s VTG turbochargers, the normal fixed nozzle ring upstream of the turbine is replaced by a nozzle ring with adjustable vanes. Under electronic control, the adjustable vanes allow the pressure of the exhaust gases impinging on the turbocharger turbine to be regulated. This varies the speed of the compressor wheel and so allows the quantity of charge-air delivered to the engine’s combustion chambers to be varied.
“VTG technology thus allows close matching of the power the engine produces to the power needed to propel the ship at a given time and under prevailing load and sea conditions,” Fusstetter added. “The benefits are optimized fuel consumption and related exhaust emissions. Further, the ability to regulate charge-air delivery across the engine’s complete operating profile gives improved engine response under load changes.”