Auxiliary and Additional Heaters in Cars, Trucks and Buses
Among mobile heating systems, the research and development focus of OWI lies on auxiliary and additional heaters which are used in cars, trucks or buses. On the one hand, they are considered in their function as heat generators for the passenger compartment and on the other hand, as additional heaters for engines. During the cold start phase in diesel engines they generate, for instance, additional heat in order to reduce the exhaust gas emissions. Furthermore, additional heaters play an important role for the new concepts of hybrid drives in order to compensate heat deficits and increase the range of vehicles battery-independently.
As, especially in cars, the space for auxiliary and additional heaters is limited, the development trend moves towards smaller and more compact devices. Requirements for the burner design and an increasing thermal load on the materials used must be taken into consideration. Moreover, it is important that processes from the fuel metering to the heat transfer into the heating medium are coordinated optimally and emission limit values are fulfilled.
OWI is active in the following research and development fields regarding auxiliary and additional heaters:
- development of combustion systems that can be run by fuels available on board,
- research concerning the suitability of various fuels for the operation of auxiliary heaters, especially with regard to regenerative and biogenic fuels in different blends,
- Investigation and optimisation of the emission behaviour of pre- and auxiliary heaters
- Investigation of surface evaporation in heating devices concerning deposit formatio
- participation in the development of existing devices with regard to the integration of auxiliary and additional heaters into different vehicle types and models and
- research on the resistance of materials which are used for the production of heaters (Project GObio).
- With the help of attempts the stability of materials is estimated under fluctuating thermal change load. By means of strength calculation (finite element method FEM) highly loaded areas of the devices can be identified and an optimised constructive construction be determined or if necessary alternative materials be recommended.
Advancement of Existing Devices
A smooth start and operation of auxiliary heaters in all vehicle types and models cannot be taken for granted. For instance, due to biogenic shares in the fuel, deposits can occur in the burner, at the vaporiser or distribution system and in the fuel pipes. Usually, individual adaptations are necessary for the integration in a vehicle. OWI supports companies of the automobile supply industry by modelling and simulations as well as practical investigations.
Furthermore, the use of different fuel types and blends of regenerative fuels can affect the operation of auxiliary heaters. Bio ethanol-mixtures, such as E85, can have different characteristics that can effect evaporation and combustion leading to malfunctions. Furthermore, OWI supports the advancement of existing devices with fundamental research, for instance, the development of fuel sensors aiming at a fuel-dependent control of auxiliary heaters.