There has been plenty of coverage of BMW’s Efficient Dynamics strategy over the last few days (see article) – which aims to reduce CO2 emissions and fuel consumption while increasing vehicle performance. However, how does this strategy apply to battery electric vehicles?
The answer is that BMW is looking to extend the range of electric cars with a host of new techniques that come under the general heading of “Intelligent Energy Management” – and one of the key focus areas has been using heat pumps and infrared systems in compartment heating.
According to BMW, the efficient delivery of heat to the passenger compartment is particularly challenging with electric and plug-in hybrid cars, especially when temperatures outside are cold. However, heat pumps, which are regularly used in the housing sector, offer a potential solution.
Similarly to how they are used for heating buildings, a heat pump in a car uses ambient heat from the surrounding air. With an air conditioning compressor, the refrigerant is compressed before being elevated to a higher temperature.
For use in a car, the refrigerant circuit has been extended with additional regulators and components and in addition to using the heat from the air outside, it also makes use of heat originating in the vehicle. The process is controlled by an intelligent thermal management system.
It is believed that by using heat pumps, about 50 per cent of the energy needed to heat an interior can be saved: and this translates to an extension of range of between 10 and 30 per cent when the outside temperature is freezing.
In addition, BMW is looking at infrared heating surfaces. Thermal radiation from infrared heating surfaces can provide a type of warmth comparable to that of an infrared lamp. When used in electric vehicles the benefits are multiplied because an electric car relies on electrical energy to maintain temperatures at comfortable levels.