Research

Warm-up Behaviour of Combustion Engines

An intelligent thermal management optimises the heat flows in the engine with the goal of lowering fuel consumption and emissions. In order to identify suitable measures and to complete a cost-use analysis, a simulation model was developed as part of the project. This made it possible to realistically represent the engine warm-up. In addition to heat input changes within combustion, the model took into consideration auxiliary heating sources, loading cycle influences, tribological measures and an active piston crown cooling. The theoretical and practical tests for validating the simulation data were carried out on a 4- cylinder common rail diesel engine with 2.0-litre cubic capacity. In this way, measures with the greatest potential in the warm-up phase were identified. Through the use of low-friction oils, consumption in the warm-up phase can be lowered by 3 per cent. As the simulation model is transferrable to other engines, it can be widely applied throughout the automotive industry.

» With the thermal engine model, it is possible to assess constructive measures relating to improved warm-up behaviour. «
Prof. Dr.-Ing. Hermann Rottengruber | Institute of Mobile Systems (IMS | OVGU Magdeburg)

Motivation

With the help of an optimised warm-up phase, combustion engines can be designed more efficiently. The measures for accomplishing this can be summarised under the heading “thermal management”. An intelligent thermal management aims to optimise the distribution of heat in the engine and by doing this to lower fuel consumption. In order to identify effective measures, models are necessary that realistically represent heat flows in a combustion engine's warm-up phase.

Methodology

The theoretical and practical work was based on tests conducted on a reference engine, a 4- cylinder common rail diesel engine with 2.0-litre cubic capacity. To simulate the engine warm-up time, a thermal network was used that showed the heat distribution in the components. To consider the changes in heat inputs owing to wall heat dissipation and friction in the warm-up phase, the thermal network was coupled with a combustion model. In the theoretical work, additional models for a piston crown cooling and a camshaft phasing adjustment were examined. The validation of the entire model occurred on the test stand which was also used for tests of technical measures with high fuel reduction potential. The transferability of the simulation model was tested using two comparison engines.

Result

The standing coolant – a very small volume flow for cooling the engine – as well as the use of a friction-modified oil as lubricant brought the greatest fuel economy, with 3 per cent. But also very simple procedures such as the choice of coolant with a very high ethylene glycol content or a reduction in oil lowered consumption by up to 1.8 per cent in the warm-up phase. A variable piston crown cooling in connection with a variable oil pump not only resulted in the possibility of optimising the warm-up phase, but also sustained savings potential once the operating temperature was reached. With the simulation model, a tool is available to test the effectiveness of thermal management measures. It is also transferable to other engines with the same general principle, so that numerous applications in the area of thermal management of engines are possible.

Documentation

Engine Heat Transfer I | Simulation of the heat transfer in combustion engines for reducing friction and CO2 emission under warm-up conditions | Project No. 1034 | AiF Funding ID: 16349 BR

Engine Heat Transfer II | Proof of the predictive power of the thermal motor model for the evaluation of design measures in terms of an improved warm-up behaviour | Project No. 1111 (self-financed)

Engine Heat Transfer III | Simulation of the heat transfer in combustion engines for reducing friction and CO2 emission under warm-up conditions | Project No. 1047 (self-financed)

Themis

Status
Finalised

Programme
Public & FVV Funding

Budget
659,401.00 EUR

Time Period
2010-04-01 to 2012-03-31 Part I
2012-07-01 to 2013-02-28 Part II
2013-09-01 to 2015-08-31 Part III

Federal Ministry for Economic Affairs and Energy (BMWi)

Scharnhorststrasse 34-37
10115 Berlin
Germany

German Federation of Industrial Research Associations (AiF) e.V.

Bayenthalgürtel 23
50968 Cologne
Germany

Research Association for Combustion Engines (FVV) eV

Lyoner Strasse 18
60528 Frankfurt am Main
Germany

Industry

Dipl.-Ing. Felix Klingebiel | I+II

Dipl.-Ing. Andreas Rundkowski | III
Volkswagen AG

RTD Performers

1 | Institute of Mobile Systems (IMS) | Mechanical Engineering Department (FMB) | Otto-von-Guericke University Magdeburg (OVGU)

Head of Research:
Prof. Dr.-Ing. Hermann Rottengruber

Research Associates:
Dr.-Ing. Volker Zeitz
Johannes Oder, MSc


2 | Institute of Fluid Dynamics and Thermodynamics (ISUT) | Faculty of Process and System Engineering (FVST) | Otto-von-Guericke University Magdeburg (OVGU)

Head of Research:
Prof. Dr.-Ing. Jürgen Schmidt

Research Associate:
Dipl.-Wirt.-Ing. Patrick Varga

Otto-von-Guericke-University Magdeburg (OVGU)

Institute of Mobile Systems (IMS)/Chair of Energy Conversion Systems for Mobile Applications (EMA)

Universitätsplatz 2
39106 Magdeburg
Germany

Otto-von-Guericke-University Magdeburg (OVGU)

Institute of Fluid Dynamics and Thermodynamics (ISUT)

Universitätsplatz 2
39106 Magdeburg
Germany

Project Management

Ralf Thee

FVV
+49 (0) 69 6603 1349
+49 (0) 69 6603 2349


Research Association for Combustion Engines eV

Lyoner Strasse 18
60528 Frankfurt am Main
Germany
T +49 69 6603 1345