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Exergy and Energy Analysis of HP and LP EGR-system
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines. (CCGEx)
KTH, School of Engineering Sciences (SCI), Mechanics. (CCGEx)
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines. (CCGEx)
(English)Article in journal (Other academic) Submitted
Abstract [en]

The emission legislation throughout the world is getting moreand more stringent. Especially in the US and Europe, dieselengine manufacturers are facing big challenges in order tokeep their engine emissions within the limits. In addition totraditional legislation of harmful emissions, the emission ofCO2, i.e. the fuel consumption, is starting to be subject of newlegislation. Many measures that control the harmful emissionscounteract the reduction of fuel consumption. After treatmentsystems for example increase backpressure, thus lowering theengine efficiency.Exhaust gas recirculation (EGR) is an important tool foremission control in modern diesel engines. The EGR-loopinduces some pumping losses thus decreasing the overallengine efficiency. Many studies have been published that aimat minimizing these losses. The use of a low-pressure EGRloop is one of the most common ways to alternate the system.This study compares a low-pressure (LP) and a high-pressureHP) EGR-system with focus on single components.To analyze the gas exchange system, both energy and exergybalance methods can be used. In this study, both methods arecompared and specific advantages and disadvantages areshown. It is shown that the exergy analysis contains usefulinformation for engine development regarding the efficiencyof single components and their influence on the entire systems performance.

Keyword [en]
high-pressure EGR, low-pressure EGR, HP-EGR, LP-EGR, EGR, Exergy
National Category
Energy Engineering
URN: urn:nbn:se:kth:diva-140847OAI: diva2:692860

QS 2014

Available from: 2014-02-02 Created: 2014-02-02 Last updated: 2014-02-03Bibliographically approved
In thesis
1. Efficiency and Mixing Analysis of EGR-Systems for Diesel Engines
Open this publication in new window or tab >>Efficiency and Mixing Analysis of EGR-Systems for Diesel Engines
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The reduction of fuel consumption and the reduction of toxic emissions are the main goals of research and development in the area of internal combustion engines. The use of exhaust gas recirculation (EGR) to come further in that direction is today an established method for diesel engines. EGR reduces the emissions of nitrogen oxides with a low penalty in fuel consumption.

The increasingly hard regulations on emissions put high pressure on the manufacturers to improve these systems. The present work aims at increasing the knowledge in the area of EGR. Two of the main challenges when applying EGR are addressed, efficiency and mixing.

The efficiency of the EGR-system is analyzed, focusing on keeping the fuel penalty low for a given EGR-rate. Different layouts of the EGR system are studied and compared regarding their stationary and transient properties. Exergy analysis is used to show the potential for improvement in different system components. In the same time, exergy analysis as a tool is introduced and compared to energy analysis of a system. The usefulness of exergy analysis of the entire gas exchange is shown by the example of a heavy-duty diesel engine.

The problem of EGR and air mixing is approached by a detailed study of the mixing process in a heavy-duty diesel engine. Different methods for the measurement of EGR distribution are presented and compared. Additionally, the possibility to predict the mixing effects by 1-D and 3-D simulation is assessed. It is shown that the mixing between air and EGR is highly dependent on the pulsating nature of the flow. The EGR is shown to be transported in packets in the air flow. This leads to the conclusion that mixing not only at the mixing point, but also mixing in flow direction needs to be optimized, as the distribution of EGR between the cylinders is dependent on the timing between the passage of the EGR packets and the valve opening time.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. viii, 75 p.
TRITA-MMK, ISSN 1400-1179 ; 2014:01
EGR, Exergy, mixing, pulsating flow, HP-EGR, LP-EGR, high-pressure EGR, low-pressure EGR
National Category
Other Mechanical Engineering
urn:nbn:se:kth:diva-140850 (URN)978-91-7501-997-0 (ISBN)
Public defence
2014-02-28, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 14:00 (English)

QC 20140203

Available from: 2014-02-03 Created: 2014-02-02 Last updated: 2014-02-03Bibliographically approved

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Reifarth, SimonTillmark, NilsÅngström, Hans-Erik
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