F O C U S 3 1 to be simulated and the interactions reproduced. To this end, AVL has built a complete vehicle system model, consisting of the main model components of the engine, the auxiliary units, the powertrain, the ORC and the vehicle cooling system. This overall model is directly linked to the control logic, so that optimal control algorithms can be developed based on the model. Given the extensive analyses and tests that AVL has carried out on a variety of WHR system specifications, AVL can draw on a comprehensive library of parameterized and validated (sub) system models. These models allow engineers to make fast and reliable statements on the efficiency of different WHR concepts in real driving and optimize the complete system for each respective application case. This simulation-based development methodology is the only way to achieve such a high degree of optimization in a system of this complexity. Conventional hardware development of single components and subsequent development of the complete system on the test bed or in the vehicle are not suited. INTELLIGENT CONTROL One of the key components of safe, robust and efficient WHR system operation is the operating strategy and the control logic to which it is mapped. Over recent years, AVL has developed a model-based closed-loop control system that can be used for a variety of WHR concepts and specifications. The AVL WHR control technology enables optimum operation with maximum WHR efficiency, system security and coverage of dynamic vehicle conditions. These control algorithms are implemented in a rapid prototyping control unit to enable WHR operation on the engine testbed and in the vehicle. RELIABLE SAFETY CONCEPT One critical aspect, particularly when ethanol is chosen as a working fluid, is having a reliable and comprehensive safety concept in place. Based on a detailed hazard analysis, AVL has developed hardware and software measures over the last years that permit the safe operation of ethanol as WHR working fluid, both on the engine test bed and in vehicles on public roads. Aside from functional safety, a sophisticated safety concept is additionally of crucial significance in view of minimal product costs, maximum system efficiency and durability of WHR components. TESTING AND VALIDATION A further challenge for the integration of the WHR technology is the present lack of experience in the entire industry as to how these systems behave with regard to durability and reliability of the components and subsystems. Based on the AVL Load Matrix methodology, AVL has created corresponding test and validation plans. They are based on the possible combinations of components and damage types that are systematically analyzed and evaluated. This ensures that on the one hand the necessary reliability and durability objectives are achieved and, on the other, that the required testing measures are reduced to a minimum. EXTENSIVE WHR EXPERTISE FOR DIFFERENT MARKETS Not least due to the use of its tools and WHR methodology, AVL has also assumed a leading role in the development and integration of these complex systems. The comprehensive experience so far gained can now be put to use in a variety of applications – on-road, off-road and steadystate applications. The specialists at AVL can design the system best suited for any of these applications and develop it to series maturity. One of AVL’s most recent WHR projects is the development of a near-series WHR system in cooperation with CNH INDUSTRIAL for a truck for long distances that is also going to be made available at AVL in an IVECO STRALIS demonstrator vehicle. Right now, a transient optimization is being carried out on the engine test bed, then the on-road vehicle tests will follow. < > Demostrator truck with near series WHRsystem.
FOCUS_Aug_2015_E
To see the actual publication please follow the link above