Energy management of vehicles is an important issue to meet the targets of CO2-emission regulations of vehicles. The variety of recently introduced vehicle concepts including HEVs and EVs imply a remarkable optimisation potential. Therefore a simulation method was developed which allows the consideration of multiple vehicle topologies with respect to driving performance, vehicle dynamics and energy management. Different user-related and legal-based driving cycles for both passenger cars and commercial trucks were analysed to verify energy flows and CO2 emissions. The energy saving potential of waste heat recovery using thermoelectric generators is presented as an example application.
The reduction of CO2 emissions and fuel consumption is still the main requirement for the development of new vehicle drive trains. Several technically interesting solutions are intensively developed or will have their start of production soon. Some of them are already well known, but due to cost reasons they are not in production until now. One example is thermal management technique, which uses energy losses to heat up the engine faster to reduce the friction torque and therefore the fuel consumption. Another approach is the electrification, which covers the use of electrically driven auxiliaries, hybrid and electric vehicles. Simulation got a completely new significance for the successful and fast development. On the one hand it is useful and even necessary to assess and select the various numbers of possible solutions with complex interactions virtually. On the other hand the influence of particular solutions to the fuel consumption is within the measurement accuracy, which means that simulation is the only way of assessment.
This paper describes the simulation of the thermal behavior of hybrid vehicles as well as the energy recuperation from exhaust gas by means of thermo electrical generator for selected applications under the aspect of CO2 reduction. For the virtual consideration the commercial 1D thermal management software KULI with integrated driving simulation module for the evaluation of driving cycles was used.
There is high potential in the hybrid drive technology for reducing fuel consumption and CO2 emissions. The use and requirements of a hybrid drive for commercial vehicles differ in many ways from the one of hybrid passenger cars. The success of hybrid solutions for commercial vehicles relies primarily on significant fuel savings, whereas energy storage and energy management play an important role.
This paper shows a simulation model which has been used for the dimensioning and detailed simulations of hybrid drive trains. To simulate the thermal effect, a co-simulation environment between longitudinal dynamics and thermal management software has been applied. The longitudinal dynamics software calculates the propulsion power which determines the thermal load of the components. Particular attention has been directed to electrical and thermal behavior of the high-traction battery. The coupling of longitudinal and
thermal simulation enables a realistic calculation of the energy use, since the effects such as the change of efficiency by temperature and load effect can be considered. This behavior also plays an important role in the development and tuning of the vehicles’ components and operating strategy.
Finally this application shows simulated data of a hybrid commercial vehicle with a lithiumion battery. For these simulations standardized driving cycles (HUDDS, JE05, …) and also cycles with a high proportion of urban driving have been simulated. These simulations show a meaningful influence on the temperature of the components, especially the battery.
For a higher hybrid market share in the future, the development of electrical components, especially energy storage systems with high power and energy densities and the reduction of system cost and weight will be essential.
This paper describes how the hybridization of conventional vehicles affects the cooling system layout. Combustion engines, electric drives, power electronics and batteries run at different temperature levels, thus, the heat loss should dissipate to individual cooling circuits. To ensure safe and reliable operation a thorough design of the cooling system is required. In the second part of the paper, the system layout for a SUV is shown. The hybrid vehicle presented here uses the power from an internal combustion engine and two electric drives. It features three different cooling circuits. The layout process is supported by a sophisticated simulation technique: by means of co-simulation of the mechanical, electrical and thermal systems, the system behaviour has been analyzed under various ambient conditions and vehicle loads. The results of these simulations will be the basis for the final system layout and thermal management strategy of the vehicle.
Different cooling systems for severa vehicles are replaced by a single one fulfilling the demands for all vehicles. This system is further optimized by choosing its components from an assortment and by changing their dimensions and further parameters (e.g. transmission ratios). The model of the cooling system is evaluated with a commercial thermodynamic cooling simulation system tool. Further results, as price and mass of the sub-components, are considered outside of this tool. The optimizing cooling systems in terms of thermodynamic efficiency, and minimized operating and material cost.
The engine warm-up after a cold start depends not only on the engine, the driving cycle and on the vehicle itself, but also on the behavior of systems like cooling circuit and power train. The individual systems stand in interaction both with the engine as well as with the other systems. This requires for the simulation of the thermal management system that all relevant subsystems are simulated simultaneously and that the interaction between the individual systems is being considered in a correct way. Therefore, a generic simulation platform was developed. The main advantage of the platform is in being able to couple the simulation models without the need of special interfaces between the individual programs. Based on an example, the modeling of the individual subsystems of the vehicle is shown. For the verification of the single subsystems experimental measurements on a vehicle dynamometer have been performed. The comprehensive vehicle model is verified with the measurement data of a ‘real-world’ driving cycle. Key parameters such as coolant temperature, engine temperature, and cabin temperature are compared therefore. Based on an example, the modeling of the individual subsystems of the vehicle is shown. For the verification of the single subsystems experimental measurements on a vehicle dynamometer have been performed. The comprehensive vehicle model is verified with the measurement data of a ‘real-world’ driving cycle. Key parameters such as coolant temperature, engine temperature, and cabin temperature are compared therefore.
Reliability of CAE processes is one of the major tasks of development groups within the automotive business in our days. Since more than 15 years ECS is dealing with the simulation of vehicle thermal management including the engine cooling package as well as the HVAC system. For these purposes the 1D software (KULI) and various 3D approaches are used to analyze the thermal efficiency of such systems. This paper shows examples where 1D and 3D simulations were combined to increase the reliability of the results.
The wide experience in thermal management for vehicles with combustion engine based drive trains could be used to optimize fuel cell driven vehicles. For the simulation task, 1d software KULI was used. By comparing two vehicles of similar size, one with combustion engine the other with a fuel cell, differences in the thermal behaviour were highlighted. For two typical operation points, relevant for the layout of cooling systems, the vehicles were compared. Additionally, the behaviour for a transient cycle with significant fractions of high load was verified. To reach temperature levels of the fuel cell vehicle the heat exchange area had to be increased by 70% compared to the conventional vehicle. Also water flow and fan speed had to be adapted.