What is turbocharging & Where did it start?
In 1905, a “highly supercharged compound engine,” referring to the coupling of a four-stroke diesel engine with an axial turbine and axial compressor mounted on a common shaft was patented by Dr Alfred Büchi. This marked the birth of exhaust gas turbocharging, and the key ideals remain unchanged to this day.
From these comparatively humble beginnings, few would have imagined the impact this staple of forced induction would have on the modern world. Far from being an accessory to improving engine performance, turbocharging has become possibly the key enabling technology in engine development. All areas of modern internal combustion engines, from motorcycles through to marine engines avail of the significant advantages has been brought about by turbocharging.
- 1924 – Brown Boveri capitalised on the idea and built the first heavy duty turbocharger for use on an experimental two-stroke engine.
- 1926 – the first practical application of turbocharging of large marine engines in German passenger liners.
- 1945 – the world’s merchant shipping fleet doubled in size, creating the market required for turbocharging to really flourish.
- 2010 – It is widely accepted that 90% of global trade is carried by sea, equating to approximately 8.4 billion tonnes of cargo, with turbocharged two-stroke diesels being by far the dominant engine configuration used in deep sea shipping (amounting to 85% of all new orders for merchant ships).
Where it stands today?
The pinnacle of modern marine engine development is the Wärtsilä-Sulzer RT-flex96C, which in its largest 14 cylinder variant produces 114,800bhp at 102 rpm. This exceeds 50% brake thermal efficiency and is recognised as the largest reciprocating engine in the world. These statistics would quite simply have been unimaginable without the inclusion of exhaust gas turbocharging. Being a two-stroke diesel, the benefits of turbocharging are even more deeply rooted than for four-stroke engines, which although would suffer a reduction in power output and efficiency without a turbocharger, can run quite happily in a naturally aspirated configuration. By comparison, forced induction is essential for the operation of two-stroke engines used in marine applications.
This technology is every bit as relevant and important today as it was at its inception. The same basic challenges remain, but have now been supplemented by an increased environmental awareness that has brought about legislation which can only be met with the help of further developments to the turbocharger. In spite of the passage of time and the development of innumerable new technologies, the prevalence of and challenges presented for turbocharging in the marine sector show no signs of abating.