The Turbo
One way in which we can improve emissions of current petrol/diesel cars.
One way in which we can improve the efficiency of a combustion engine is to implement the use of a turbocharger. Turbochargers were originally for ‘racers’ as they allowed the car to go fastest without having to increase engine size, however as government emission regulations are becoming stricter, the turbocharger now plays a greater role.
What is a turbocharger? And how does it work?
‘A small turbine turned by the waste gases from an engine that pushes the fuel and air mixture into the engine at a higher pressure, so increasing the power produced by the engine’ [1].
Naturally aspirated engines take air from the surroundings into the engine, where it mixes and ignites with the fuel to produce power. A turbocharger uses waste exhaust gases to spin a turbine connected to a compressor. The compressor wheel compresses the air and feeds more air back into the engine. With more air expansion, the engine gains more power. The turbine and compressor are connected by an adjoining shaft. As the turbine rotates, it subsequently turns the compressor wheel and is designed to rotate at over 100,000rpm. An oil lubricant is used on the shaft and connecting bearings to reduce the friction between components as they rotate [2].
The Ideal gas law states, with a constant volume and increasing pressure, the temperature must increase proportionally. Therefore, before the air in the compressor can be fed into the engine, an intercooler must be introduced to reduce the temperature of the air.
How does it reduce CO2 emissions?
By increasing the combustion efficiency with which an engine burns diesel, a turbocharger increases the amount of energy diesel produces and reduces emissions by converting a greater percentage of diesel fuel into carbon dioxide or water as opposed to a toxic emission.
Turbochargers are known for making cars go faster but they actually help reduce the amount of CO2 emissions in a petrol/diesel car. It is a cost-effective route. The basic concept of a turbocharger is to recycle wasted energy from exhaust gas, transforming more of the fuel energy consumed into power. A turbocharged engine, therefore, offers improved fuel economy, less CO2 emissions and better performance over a non-turbocharged engine.
Key improvements made by the implementation of a turbocharger:
- Decrease size of engine, but retain power
- Smaller engine – means less weight
- Better fuel efficiency
Current technology improvements
Cummins Turbo Technologies is leading in the development of engines for medium to heavy duty vehicles and have conducted extensive research into ways of improving their emissions to align with the government standards. At this stage in the blog, it is clear that petrol and diesel engine production will eventually have to stop however, this will not happen overnight, and Cummins are attempting to make any necessary adaptions until a suitable transition option is possible.
The Exhaust Throttle Valve (ETV) was developed for the aftertreatment of thermal management and exhaust braking. It offers flexible design needs which means it can be adapted and configured with other products and reduces NOx and hydrocarbon (HC) emissions [3].
New wastegate technology has been developed to prevent the turbocharger from over-speeding. A wastegate is a valve that controls the flow of exhaust gases to the turbine wheel, the diversion of exhaust gases helps regulate the speed of the turbine which is connected to the compressor. The wastegate turbochargers are both cost effective and reliable, with a 3% increase in efficiency [4].
As discussed in the previous blog, I believe it will be harder for trucks and lorries to transfer to electric until the mileage range of those vehicles has drastically improved and with the developments made at Cummins, it shows that we have time to make these advances with the electric vehicle range. The technology improvements developed by Cummins continues to meet the emission standards set by the government and therefore we can focus our attention primarily onto cars, as other vehicles are polluting less and have the necessary improvements to temporarily exclude them from the transition.
[1] https://dictionary.cambridge.org/dictionary/english/turbocharger
[2] https://www.youtube.com/watch?v=ji3MpElXr4s
[3] https://www.cummins.com/news/2020/03/09/cummins-turbo-technologies-launches-exhaust-throttle-valve
[4] https://www.cummins.com/components/holset-turbo-technologies/holset-turbochargers