Thermal recuperation of waste heat is able to drastically reduce the consumption of vehicles. At the moment, no system is commercially available on the market. Even though the development of OEM advances, a fundamental investigation of working media and their influence on the component layout is necessary in order to understand the complex interrelations. Recuperation of waste energy via equivalent additional matters poses a high consumption saving potential. For the thermal recuperation of the lost heat of an engine, concepts have not been established yet in the motor vehicle sector, even though this source of waste heat has, energetically, the highest potential with more than 60%. During thermal recuperation heat is converted into chemical, electrical and mechanical energy or can be used to power a cooling engine. Examples for suitable concepts in passenger cars at an experimental stage have already been published at subject-specific conferences. At the time being, published data about similar systems for use in heavy goods vehicles are missing. In HGVs, similar improvements of efficiency can be basically expected. Although the diesel engine is operated closer to the optimum in the map, leading to a reduction of exhaust enthalpy in relation to engine performance, EGR and charge air cooling offer additional interesting energy sources for thermal recuperation and the conversion into mechanical work. A special constraint, both in HGVs and passenger cars, poses the heat emission to the environment. Each kind of energy, absorbed by the exhaust or other sources in a working cycle, has to be finally emitted to the environment at a preferably low level. Overall, the use of a steam cycle process in vehicles involves many restrictive boundary conditions, which are well displayed in the listing of the following assessment criteria. They are: thermal efficiency, pressure level and ratio, part load behaviour, integration of energy (drive effusion), lubrication of the expander, thermal stability of the working medium, freezing point, environmental compatibility, compatibility of materials, complexity, space, weight, etc. First, two vehicles (passenger car, german OEM) and (HGV, MAN) are investigated and evaluated regarding the available waste heat and exhaust enthalpy in the most important operating points. On the basis of these data, all possibilities of the conversion into mechanical energy via cycle processes (Joule, Stirling, Rankine) should again be compared to each other. At the moment, the steam cycle process with water or ORC-medium seems to have the best aspects. Thus the project deals with the further investigation of the most important components of a steam cycle process, i.e. the working medium, the evaporator and the expander. They can only be assessed in a multidisciplinary collaboration of experts. Beside the relevant collaborators of both OEMs, the following institutions and companies are involved: Graz University of Technology (thermodynamics steam, cycle process and components), Delft University of Technology (thermodynamics, steam, cycle process, components, thermo physical properties, simulation programs for ORC media), Forschungsgesellschaft für Verbrennungskraftmaschinen und Thermodynamik mbH (design, expander) and Proionic (assessment of ionic fluids). Finally the assessment will also be carried out for the entire cycle process concluding with a report.
|Effective start/end date||1/02/10 → 30/11/11|
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