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On-Engine Turbocharger Performance Considering Heat Transfer
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). (Förbränningsmotorteknik, Internal Combustion Engines)
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Heat transfer plays an important role in affecting an on-engine turbocharger performance. However, it is normally not taken into account for turbocharged engine simulations.

Generally, an engine simulation based on one-dimensional gas dynamics uses turbocharger performance maps which are measured without quantifying and qualifying the heat transfer, regardless of the fact that they are measured on the hot-flow or cold-flow gas-stand. Since heat transfer situations vary for on-engine turbochargers, the maps have to be shifted and corrected in the 1-D engine simulation, which mass and efficiency multipliers usually do for both the turbine and the compressor. The multipliers change the maps and are often different for every load point. Particularly, the efficiency multiplier is different for every heat transfer situation on the turbocharger. The heat transfer leads to a deviation from turbocharger performance maps, and increased complexity of the turbocharged engine simulation. Turbochargers operate under different heat transfer situations while they are installed on the engines.

The main objectives of this thesis are:

  • heat transfer modeling of a turbocharger to quantify and qualify heat transfer mechanisms,
  • improving turbocharged engine simulation by including heat transfer in the turbocharger,
  • assessing the use of two different turbocharger performance maps concerning the heat transfer situation (cold-measured and hot-measured turbocharger performance maps) in the simulation of a measured turbocharged engine,
  • prediction of turbocharger walls’ temperatures and their effects on the turbocharger performance on different heat transfer situations.

Experimental investigation has been performed on a water-oil-cooled turbocharger, which was installed on a 2-liter GDI engine for different load points of the engine and different heat transfer situations on the turbocharger by using insulators, an extra cooling fan, radiation shields and water-cooling settings. In addition, several thermocouples have been used on accessible surfaces of the turbocharger to calculate external heat transfers.

Based on the heat transfer analysis of the turbocharger, the internal heat transfer from the bearing housing to the compressor significantly affects the compressor. However, the internal heat transfer from the turbine to the bearing housing and the external heat transfer of the turbine housing mainly influence the turbine. The external heat transfers of the compressor housing and the bearing housing, and the frictional power do not play an important role in the heat transfer analysis of the turbocharger.

The effect of the extra cooling fan on the energy balance of the turbocharger is significant. However, the effect of the water is more significant on the external heat transfer of the bearing housing and the internal heat transfer from the bearing housing to the compressor. It seems the radiation shield between the turbine and the compressor has no significant effect on the energy balance of the turbocharger.

The present study shows that the heat transfer in the turbocharger is very crucial to take into account in the engine simulations. This improves simulation predictability in terms of getting the compressor efficiency multiplier equal to one and turbine efficiency multiplier closer to one, and achieving turbine outlet temperature close to the measurement. Moreover, the compressor outlet temperature becomes equal to the measurement without correcting the map.

The heat transfer situation during the measurement of the turbocharger performance influences the amount of simulated heat flow to the compressor. The heat transfer situation may be defined by the turbine inlet temperature, oil heat flux and water heat flux. However, the heat transfer situation on the turbine makes a difference on the required turbine efficiency multiplier, rather than the amount of turbine heat flow. It seems the turbine heat flow is a stronger function of available energy into the turbine. Of great interest is the fact that different heat situations on the turbocharger do not considerably influence the pressure ratio of the compressor. The turbine and compressor efficiencies are the most important parameters that are affected by that.

The component temperatures of the turbocharger influence the working fluid temperatures. Additionally, the turbocharger wall temperatures are predictable from the experiment. This prediction enables increased precision in engine simulations for future works in transient operations.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 105 p.
Series
Trita-MMK, ISSN 1400-1179 ; 2012:08
Keyword [en]
turbocharger, Internal combustion engine, heat transfer, turbocharged engine, on-engine turbocharger, turbocharger performance
Keyword [fa]
توربو شارژر، موتور احتراق داخلی، انتقال حرارت، توربوچارجر
Keyword [sv]
turbo, turboladdare, förbränningsmotor, värmeöverföring, turboladdad motor
National Category
Vehicle Engineering Energy Engineering
Identifiers
URN: urn:nbn:se:kth:diva-93981ISBN: 978-91-7501-332-9 (print)OAI: oai:DiVA.org:kth-93981DiVA: diva2:524801
Presentation
2012-05-22, B242, Brinellvägeb 83, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20120504Available from: 2012-05-04 Created: 2012-05-03 Last updated: 2012-05-04Bibliographically approved
List of papers
1. Improving Turbocharged Engine Simulation by Including Heat Transfer in the Turbocharger
Open this publication in new window or tab >>Improving Turbocharged Engine Simulation by Including Heat Transfer in the Turbocharger
2012 (English)In: 2012 SAE International, SAE international , 2012Conference paper, Published paper (Refereed)
Abstract [en]

Engine simulation based on one-dimensional gas dynamics is well suited for integration of all aspects arising in engine and power-train developments. Commonly used turbocharger performance maps in engine simulation are measured in non-pulsating flow and without taking into account the heat transfer. Since on-engine turbochargers are exposed to pulsating flow and varying heat transfer situations, the maps in the engine simulation, i.e. GT-POWER, have to be shifted and corrected which are usually done by mass and efficiency multipliers for both turbine and compressor. The multipliers change the maps and are often different for every load point. Particularly, the efficiency multiplier is different for every heat transfer situation on the turbocharger. The aim of this paper is to include the heat transfer of the turbocharger in the engine simulation and consequently to reduce the use of efficiency multiplier for both the turbine and compressor. A set of experiment has been designed and performed on a water-oil-cooled turbocharger, which was installed on a 2 liter GDI engine with variable valve timing, for different load points of the engine and different conditions of heat transfer in the turbocharger. The experiments were the base to simulate heat transfer on the turbocharger, by adding a heat sink before the turbine and a heat source after the compressor. The efficiency multiplier of the turbine cannot compensate for all heat transfer in the turbine, so it is needed to put out heat from the turbine in addition to the using of efficiency multiplier. Results of this study show that including heat transfer of turbocharger in engine simulation enables to decrease the use of turbine efficiency multiplier and eliminate the use of compressor efficiency multiplier to correctly calculate the measured gas temperatures after turbine and compressor.

Place, publisher, year, edition, pages
SAE international, 2012
Keyword
Turbocharger, Heat Transfer, Turbocharged Engine, Simulation
National Category
Vehicle Engineering Energy Engineering Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-70200 (URN)2-s2.0-84877171285 (Scopus ID)
Conference
SAE 2012 World Congress & Exhibition, April 24-26, 2012, Detroit, Michigan, USA
Projects
On-Engine Turbocharger Performance
Note

QS 2012

Available from: 2012-04-24 Created: 2012-01-30 Last updated: 2016-12-22Bibliographically approved
2. Turbocharged SI-Engine Simulation with Cold and Hot-Measured Turbocharger Performance Maps
Open this publication in new window or tab >>Turbocharged SI-Engine Simulation with Cold and Hot-Measured Turbocharger Performance Maps
2012 (English)In: Proceedings of ASME Turbo Expo 2012, Vol 5, ASME Press, 2012, 671-679 p.Conference paper, Published paper (Refereed)
Abstract [en]

Heat transfer within the turbocharger is an issue in engine simulation based on zero and one-dimensional gas dynamics. Turbocharged engine simulation is often done without taking into account the heat transfer in the turbocharger. In the simulation, using multipliers is the common way of adjusting turbocharger speed and parameters downstream of the compressor and upstream of the turbine. However, they do not represent the physical reality. The multipliers change the maps and need often to be different for different load points. The aim of this paper is to simulate a turbocharged engine and also consider heat transfer in the turbocharger. To be able to consider heat transfer in the turbine and compressor, heat is transferred from the turbine volute and into the compressor scroll. Additionally, the engine simulation was done by using two different turbocharger performance maps of a turbocharger measured under cold and hot conditions. The turbine inlet temperatures were 100 and 600°C, respectively. The turbocharged engine experiment was performed on a water-oil-cooled turbocharger (closed waste-gate), which was installed on a 2-liter gasoline direct-injected engine with variable valve timing, for different load points of the engine. In the work described in this paper, the difference between cold and hot-measured turbocharger performance maps is discussed and the quantified heat transfers from the turbine and to/from the compressor are interpreted and related to the maps.

Place, publisher, year, edition, pages
ASME Press, 2012
Keyword
Turbocharger, Heat transfer, Performance Map, Turbocharged Engine
National Category
Energy Engineering Aerospace Engineering Vehicle Engineering Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-70231 (URN)10.1115/GT2012-68758 (DOI)000324956100070 ()2-s2.0-84881241280 (Scopus ID)978-079184471-7 (ISBN)
Conference
ASME Turbo Expo 2012: Turbine Technical Conference and Exposition, GT 2012; Copenhagen; Denmark; 11 June 2012 through 15 June 2012
Projects
On-Engine Turbocharger Performance
Note

QC 20131106

Available from: 2012-03-09 Created: 2012-01-30 Last updated: 2014-10-01Bibliographically approved

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