BMW has given us a sneak peek at several new heat-related technologies, which aim to reduce emissions and improve fuel efficiency.
The first system under development could virtually eliminate cold starts by fully encapsulating the engine with materials typically used to insulate a vehicle's underfloor. This allows a warm engine to "cool down much more slowly after being switched off and still has a temperature of approximately 40 degrees Celsius after 12 hours. Each degree Celsius above the ambient temperature reduces fuel consumption by 0.2%."
The second system is literally from the space age, albeit the 1960s. Using an electricity-generating principle similar to the one used on vintage space probes, BMW is working on integrating a thermoelectric generator (TEG) into the exhaust gas recirculation (EGR) cooler. The generator would use "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." While interesting and boring at the same time, the system would reduce fuel consumption and CO2 emissions by up to 2%.
The final system, dubbed the exhaust gas heat exchanger, would warm the drivetrain to reduce friction in components such as the gearbox. It would work by conveying heat from the exhaust to the oil in the automatic transmission. In a similar fashion, BMW is also considering a system that uses a heat exchanger to power the electric heater that is equipped on many diesel-powered vehicles.
Ok, sounds good, but why does all this techno-wizardry matter? According to BMW, "Even a highly efficient engine can only convert about one-third of the energy contained in fuel to actually propel a car. Two-thirds is lost as waste heat via the car's exhaust and radiator."
Most of the systems are currently in a prototype stage, so it'll likely be several years before we can expect to see them on production vehicles. Regardless, BMW says their engineers are carefully considering which objectives can be best reached with available technology.