BMW is currently working on new technologies to better manage heat released from its vehicles. By improving heat management, fuel consumption and CO2 emissions can be reduced. Even a very fuel efficient engine can only convert about one-third of the energy contained in fuel to actually propel a car.
The rest is lost as waste heat via the car’s exhaust and radiator. To be more specific the auto maker is working on three systems including technologies to eliminate cold starts, convert heat from a car’s exhaust into electricity and use waste heat for interior heating.
To eliminate cold starts, BMW is working on improving heat insulation of engines (pictured below) that can help prevent them from cooling down quickly and retain as much residual heat as possible for the next start. With the technology that is being developed, the engine will take longer to cool down and even after 12 hours, engine temperature can still be figured at about 40 degrees Celsius.
BMW claims that each degree Celsius above the ambient temperature can help reduce fuel consumption by 0.2%. To help achieve better heating, a vehicle will be surrounded by fully clad walls and panels using materials that are normally used in the car’s underfloor for insulation.
Heat can also be converted into electric power. The automaker says that between 3 and 8% of the total fuel consumed by modern cars is due to the rising number of electricity-dependent features. BMW is testing a component called a thermoelectric generator (pictured below).
This generator uses the effect of the temperature gradient in thermoelectric semi-conductor elements generating electrical voltage (the Seebeck Effect). The bigger the difference in temperature, the higher the voltage generated. Exhaust gas temperatures, which are usually between 300 and 900 degrees Celsius, are on the hot side of the generator, and engine coolant is used for the cold side.
Basically up to 250 W of energy can be produced by integrating the component with the exhaust gas recirculation cooler. 250 W equals to about half the on-board electricity consumption in a BMW 5 Series. This can help reduce fuel consumption and CO2 emissions by up to 2%.
The final technology of the heat management idea is an exhaust gas heat exchanger. This system can be placed close to the catalytic converter and it can convey heat to other components or areas like the interior. It can replace the need for electrical heating modules which consume additional fuel (by about 1 litre per 100 kilometers).
Furthermore, the feature can also be used to help warm up components like the transmission (example, oil in the automatic transmission). The above mentioned technologies are in testing stages hence it can take years before we can actually see them in production cars.