Reducing fuel consumption

Reducing fuel consumption

Over the past twenty-five years, combustion improvements, efficient filters and catalytic converters have virtually eliminated emissions of nitrogen oxides and particulate matter from vehicle traffic.

But the problem of carbon dioxide emissions contributing to the greenhouse effect still remains to be solved.

Increased efficiency
Today's diesels have an efficiency level of about 40%. Research indicates that a level of over 50% can be achieved.

We are working on a multitude of solutions that will contribute to increased fuel efficiency in the future. This includes engine combustion efficiency, powertrain friction reduction, waste-heat recovery, vehicle rolling resistance, air drag reduction, and improved controls.

Combustion optimization
The Volvo Group has a long history of improving and optimizing combustion, but this continues to be a critical area for efficiency gains. This includes fundamental work with fuel injection frequency, timing, shaping at pressures in excess of 2500 bar, ever improving turbochargers, piston bowl shapes and engine breathing.

Waste heat recovery
Although diesels are the most efficient engines in common use, still over half the fuel energy is wasted as heat in the exhaust and cooling systems. We are working to develop Rankine bottoming cycles that can work within vehicle constraints to extract useful mechanical or electrical energy.

Exhaust heat exchangers
One technology that reduces nitrogen oxide emissions involves re-circulation of exhaust gas into the engine cylinders. In this process, a heat exchanger can be used for recuperating unwanted heat carried by the gas. This benefits the exhaust gas after treatment system and reduces fan engagement.
Large heat exchanger systems may require more space than is currently available on the tractor, meaning that heat exchange systems may be fitted on truck trailers in the future. 

New aircraft engine concepts also include heat exchangers to reduce the air flow temperature in the engine and thereby increase engine performance.

Thermoelectric generators
Energy can also be recovered from the engine's exhaust gases using a thermoelectric generator. This device creates a current from the temperature difference across the thermoelectric elements.

It may be possible to recoup up to 10 % of the energy that passes through the system as electricity. The electricity can be stored in batteries or used for running electric auxiliaries or used for propulsion via an electric motor.

Driveline optimization
Supplying the full driveline, the Volvo Group is in a strong position to work on solutions that optimize not only the engine, gearbox and rear axle on component level - but also to optimize how they work together as a unit.

Continuous efforts are put into reducing frictional losses from the various engine and transmission components using new design and casting techniques.

Power on demand
Overcapacity is inefficient, both from the financial and environmental perspectives. It is likely that the future will see new generations of trucks designed primarily for lighter duties but equipped with the ability to access extra power and torque when needed.

Such vehicles will be particularly useful in parts of the world where infrastructure is poor.

Reducing air drag for the complete convoy
Some 30% of an average Volvo truck's air drag coefficient has been reduced over the last couple of decades. This is a result of aerodynamically optimized cab designs and accessories.

Now and in the near future, there is the potential to reduce air drag on the trailer and in the interface between tractor and trailer. Optimizing the complete vehicle combination could probably reduce fuel consumption by around 10%. However, this would require a change in the regulation on convoy length.