![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
Abstract
In power plant applications it is state of the art to recover waste heat in combined-cycle power plants. Hence, overall efficiencies are increased from 35% to more than 45%. Actually, in marine applications as well as in commercial vehicle applications, similar technologies are developed to recover waste heat. The common basis of all these applications is running only or mostly at steady-state conditions. With passenger cars the operation conditions are completely different, as passenger cars are operated under highly transient conditions. In the work presented, the characteristics of a passenger car-based internal combustion engine are analyzed. From exhaust gas temperatures and exhaust gas mass flows, the characteristic of available waste heat over load and speed is estimated. Based on this characteristic an ideal, a water-based Rankine cycle is designed and compared with different organic Rankine cycles. Finally, the expected waste heat recovery at typical passenger car operation conditions is determined by weighting the waste heat recovery characteristics with the operation conditions of the new European driving cycle (NEDC). Based on NEDC scenario, only about 0.2 kW of power could be recovered. By moving toward range extender conditions, between 2.5 and 4.0 kW would be recoverable.
NOMENCLATURE
| A | = | cross-sectional area, m2 |
| cp | = | specific heat capacity, J kg−1 K−1 |
| cw | = | aerodynamical drag coefficient, dimensionless |
| FR | = | resistance force, N |
| fR | = | resistance force coefficient, dimensionless |
| g | = | gravitational acceleration, m s−2 |
| i | = | transmission ratio, dimensionless |
| M | = | torque, N-m |
| m | = | mass, kg |
| n | = | engine speed, s−1 |
| P | = | engine power, W |
| = | heat flux, W | |
| r | = | radius, m |
| T | = | temperature, K |
| ΔT | = | temperature difference, K |
| t | = | time, s |
| = | volumetric flow rate, m3 s−1 | |
| v | = | velocity, m s−1 |
Greek Symbols
| α | = | relative throttle angle, dimensionless |
| β | = | ascending slope angle, ° |
| ϵi | = | gear acceleration coefficient, dimensionless |
| ρ | = | density, kg m−3 |
Subscripts
| ac | = | after catalytic converter |
| acc | = | acceleration periods |
| aero | = | aerodynamical influences |
| air | = | referring to air |
| axle | = | axle drive including differential gear |
| bc | = | before catalytic converter |
| exhaust | = | referring to exhaust gas |
| gear | = | gearbox |
| ICE | = | internal combustion engine |
| NEDC | = | referring to new European driving cycle |
| out | = | outlet of HRSG |
| throttle | = | referring to throttle angle |
| total | = | total value |
| wheel | = | referring to wheel |
Additional information
Notes on contributors
Peter Heidrich
Peter Heidrich is a professor of automotive engineering and energy systems at the University of Applied Science Kaiserslautern, Germany. He received his diploma in mechanical engineering in 1996 from Universität Stuttgart, Germany. After 9 years in the automotive industry he joined the Institute of Aerospace Thermodynamics, Stuttgart, Germany, where he received his Ph.D. in 2010. In 2011 he became a professor at University of Applied Science Kaiserslautern. His main research work is carried out in the field of hybrid power train systems and heat recovery technologies in automotive applications.
Thomas Krisch
Thomas Krisch is a mechanical engineer. He received a master of engineering in mechanical and energy systems degree in 2013 from the University of Applied Science Kaiserslautern, Germany. During his diploma studies he worked as a draftsman and constructing engineer in the field of materials handling. In his master's thesis he investigated the potential of recuperating electrical energy from the internal combustion engine's exhaust systems.