Thermal Management
Thermal management ensures the targeted use and associated needs-based redistribution of the heat produced during vehicle operation. To achieve this, all the heat sources and heat sinks must be known, as well as their time-dependent cooling and heating requirements.
One task of thermal management is to ensure cooling. This is needed for removing heat from the components concerned, and from the passenger compartment. Another objective is to use all available heat sources productively in order to conserve energy.
For example, focused thermal management strategies can be applied while the vehicle is warming up to reduce friction in the drivetrain, thus reducing energy consumption. Interior comfort for passengers is an important criteria, especially at low outdoor temperatures, since the heat needed to warm up the passenger compartment must be taken from the cooling system.
The three most important tasks of thermal management are
- Optimum design and conditioning of the vehicle cooling system
- Ensuring interior comfort
- Thermal protection of components
Thermal management is even more complex for vehicles with alternative drives, since, for example, the battery and power electronics need to be kept at consistently lower temperatures as far as is possible. Due to the higher efficiency, the quantity of available heat in the cooling system is lower, generally meaning that additional energy must be expended for interior comfort.
Numerical simulation is also extremely helpful in the thermal management development process. To design and optimize cooling systems, FKFS uses 1D simulation tools which have been specially developed for hydraulic and heat transfer applications. Components can be studied and optimized using special component test benches and 3D CFD.
Cooling System
Cooling System
A vehicle's cooling system does not just have the job of ensuring safe operation of all the vehicle's components – it must also be the right size to minimize the energy consumption for cooling. To design cooling systems, FKFS uses system simulation tools which depict the cooling system and its numerous components as a network. The results then enable specific conclusions to be drawn about the system behavior. The route can be taken into consideration by using standardized or customer-specific driving cycles and incorporating the relevant environmental conditions.
The accompanying measurements are made at FKFS, using the Institute's own thermal wind tunnel. Individual components and overall systems can be studied and optimized in the wind tunnel: both at constant operating points and in driving cycles. The measurement equipment used covers temperature, pressure and volumetric flow measurements for all operating media.
Contact
Dr.-Ing. Timo Kuthada
Ph.: +49 711 685-67615
Interior Comfort
Interior Comfort
Interior comfort can be evaluated, for example, by using the comfortable temperature in the passenger compartment. Temperature control is generally achieved by blowing heated or cooled air into the passenger compartment. FKFS has developed a special measurement system to accurately determine the individual volumetric flows of the discharge nozzles. This can be used to optimize airflow and temperature; helping improve interior comfort while simultaneously reducing energy consumption. This measurement system can also be used to study ventilated comfort seats.
At FKFS, interior comfort is investigated both experimentally – for example, by measuring the heating-up behavior of the passenger compartment – and by using numerical simulation. 3D flow simulations coupled with a thermal solver are used for this.
Contact
Dr.-Ing. Timo Kuthada
Ph.: +49 711 685-67615
Component Cooling
Component Cooling
One of the tasks of thermal management is to ensure that components are cooled under all conditions. The number of components requiring temperature control increases dramatically for vehicles with alternative drives. For example, the battery, power electronics and electrical drive each have a different permissible temperature range. Depending on the application spectrum, different media may be appropriate for cooling components, e.g. air-cooled or coolant-cooled.
FKFS uses simulations and experiments to investigate and optimize component cooling. Sometimes we also use test benches which we have developed in-house.
WHR
WHR
The potential for reducing consumption by electrifying the drivetrain is limited for heavy commercial vehicles traveling on long-distance routes. Steps to increase efficiency must be applied to the combustion engine environment; particularly promising here is waste heat recovery (WHR).
The residual exhaust gas heat can be utilized via a Rankine process or thermo-electric generators. Both concepts can result in a considerable load on the cooling circuit. They must be controlled in such a way that they use available cooling circuit reserves, without a corresponding increase in the fan power. Anticipatory control strategies can be used for this.
But there are also feedback effects on the thermodynamics of the base engine which must be compensated for, such as fresh charge loss and increasing raw nitrogen oxide emissions.
Contact
Ph.: +49 711 685-65611