Kawasaki Heavy Industries’ new KG-18-T gas engine, fitted with PBST’s two-stage-turbocharging ‘Ecocharge’ system, has achieved a world record power generation efficiency burning Japanese standard city gas.
Designed for power applications, the Ecocharge solution consists of 1 × PBST TCX23 and 1 × PBST TCA66 turbochargers that have improved its power-generation efficiency by 1.5% compared to the previous generation of the engine, delivering a world-best 51.0% in its output class. KHI reports that the engine and turbochargers have passed a durability test and are now ready for serial production.
The Ecocharge principle optimally combines a low-pressure turbocharger – usually a TCT, TCA or TCR – with a high-pressure stage for which the newly developed TCX series was designed. Ecocharge is claimed to offer increased turbocharging efficiencies in comparison to single-stage turbochargers. This is mainly owing to the intercooler positioned between the low-pressure-stage and high-pressure-stage turbochargers that significantly reduces the energy required to compress the intake air to high pressure. The resulting higher efficiencies have an instantaneous impact on the engine by advantageously increasing the air pressure during the scavenging process.
Greater charging pressure via two-stage turbochargers improves the reduction of NOx emissions through the Miller cycle, while the improved scavenging efficiencies provided by the Ecocharge system make the engine more fuel efficient.
The higher power-density generated by fitting the Ecocharge technology presents the opportunity to choose between significantly boosting an engine’s power output or reducing engine size, while maintaining engine performance.