Abstract
In future mobility, the mix of different drive trains will probably be much more diverse than it is today. According to a large number of scenario analyses, a predominant number of vehicles will continue to be based on the internal combustion engine (ICE), while an increasing number of hybrid vehicles are expected. To achieve the required reductions in CO2 emissions it is necessary to investigate all potential technologies for efficiency improvement. Therefore in this work the potential of waste heat recovery is examined for conventional and hybrid vehicles. Due to the fact that in an internal combustion engine approximately 2/3 of the fuel's chemical energy dissipates as waste heat, the potential for the recovery of this energy in all ICE driven powertrains is, in principle, high. The results of this work show that in hybrid vehicles the highest share of the energy supplied by the fuel is lost in the exhaust gas. In order to further elaborate this result, we conduct an exemplary examination of two comparable vehicles of the compact class within the worldwide harmonized light duty test cycle. Measurement data from the two vehicles at the roller dynamometer is used. The result shows that the averaged exhaust gas heat flow of the conventional vehicle is 5.0 kW. For the hybrid vehicle, driving in the charge sustaining mode, the averaged exhaust gas heat flow results in 8.1 kW. The comparison shows that the temperature level of this exhaust gas is even higher than that of the conventional vehicle. In addition, this work shows that through the higher temperatures, the exergy in the exhaust gas is higher in hybrid vehicles even if the combustion engine works with a higher efficiency. In the exemplary comparison the averaged exergy of the exhaust gas is 3.2 kW for the conventional and 5.7 kW for the hybrid vehicle. As a result of this work, the high potential for waste heat recovery in hybrid vehicles could be demonstrated.
Article PDF
Similar content being viewed by others
Explore related subjects
Discover the latest articles, news and stories from top researchers in related subjects.Avoid common mistakes on your manuscript.
Abbreviations
- \( c_{p} \) :
-
Specific heat capacity (J/kg K)
- \( \dot{E} \) :
-
Exergy flow (W)
- \( h \) :
-
Heat of combustion (J/kg)
- \( m \) :
-
Mass (kg)
- \( \dot{m} \) :
-
Mass flow (g/s)
- \( p \) :
-
Pressure (Pa)
- \( \dot{Q} \) :
-
Heat flow (W)
- \( T \) :
-
Temperature (K)
- \( U \) :
-
Internal energy (J)
- \( V \) :
-
Volume (dm3)
- \( \eta_{\rm{C}} \) :
-
Carnot efficiency (–)
- \( \varphi \) :
-
Crank angle (°)
- CO2 :
-
Carbon dioxide
- DLR:
-
Deutsches Zentrum für Luft- und Raumfahrt/German Aerospace Center
- DSG:
-
Dual-clutch gearbox
- ICE:
-
Internal combustion engine
- ORC:
-
Organic Rankine cycle
- PHEV:
-
Plug-in hybrid
- TEG:
-
Thermoelectric generator
- TEM:
-
Thermoelectric module
- TSI:
-
Turbocharged stratified injection
- WLTC:
-
Worldwide harmonized light duty driving test cycle
- WLTP:
-
Worldwide harmonized light duty vehicles test procedure
- A:
-
Ambient
- CO:
-
Coolant
- F:
-
Fuel
- HG:
-
Hot gas
- I:
-
In
- Leak:
-
Leakage
- max:
-
Maximum
- mi:
-
Average
- O:
-
Out
- W:
-
Wall
References
M. Kober, Holistic Optimization of Thermoelectric Generators for Automotive Applications: Reaching a Cost Benefit Ratio of 81€ /(g/km). (elib DLR, 2016), https://elib.dlr.de/125922/. Accessed 10 Jan 2019.
M. Kober, Thermoelectric Generators for Automotive Applications: A New Approach to Reach the Cost-Benefit Target. (elib DLR, 2016), https://elib.dlr.de/115947/. Accessed 10 Jan 2019.
M. Kober and H. Friedrich, Thermoelectric Generators (TEG) with high power density for application in hybrid cars. (elib DLR, 2016), https://elib.dlr.de/107902/. Accessed 10 Jan 2019.
C. Häfele, Entwicklung fahrzeuggerechter Thermoelektrischer Generatoren zur Wandlung von Abgaswärme in Nutzenergie, Forschungsbericht 2016-08 (Köln: Deutsches Zentrum für Luft- und Raumfahrt, 2016).
M. Kober, C. Häfele, and H. Friedrich, Methodical Concept Development of Automotive Thermoelectric Generators. (elib DLR, 2016), https://elib.dlr.de/79163/. Accessed 10 Jan 2019.
U. Kugler, J. Brokate, C. Schimeczek, and S. Schmid, Powertrain scenarios for cars in european markets to the year 2040. (elib DLR, 2017), https://elib.dlr.de/114744/ Accessed 10 Jan 2019.
G. Berckmans, M. Messagie, J. Smekens, N. Omar, L. Vanhaverbeke, and J.V. Mierlo, Energies, 10(9). (2017). https://doi.org/10.3390/en10091314.
D. Grebe and L. Nitz, Voltec–the propulsion system for Chevrolet Volt and Opel Ampera. AutoTechnology (ATZ) 11, 28–35 (2011).
WLTP DHC, Development of a World-wide Worldwide harmonized Light duty driving Test Cycle (WLTC). (UN/ECE, 2014), https://www.unece.org/fileadmin/DAM/trans/doc/2014/wp29grpe/GRPE-68-03e.pdf. Accessed 10 Jan 2019.
M. Kober, J. Electron. Mater. (2020). https://doi.org/10.1007/s11664-020-07966-6.
R. Pischinger, M. Klell, and T. Sams, Thermodynamik der Verbrennungskraftmaschine (Wien: Springer, 2009).
Acknowledgments
Open Access funding provided by Projekt DEAL.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Kober, M. The High Potential for Waste Heat Recovery in Hybrid Vehicles: A Comparison Between the Potential in Conventional and Hybrid Powertrains. J. Electron. Mater. 49, 2928–2936 (2020). https://doi.org/10.1007/s11664-020-07991-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11664-020-07991-5