E4-Mistra, a research program for the development of an energy efficient low emission exhaust aftertreatment system for heavy duty vehicles

Transcription

1 E4-Mistra, a research program for the development of an energy efficient low emission exhaust aftertreatment system for heavy duty vehicles World Renewable Energy Forum 2012 paper 0940 Jazaer Dawody Volvo Group Trucks Technology 1

2 The E4 Mistra programme The E4 Mistra is a joint research programme between academic and industrial partners. The programme is financially supported by Mistra, a Swedish Foundation for Strategic Environmental Research, and the Swedish Energy Agency. The system approach is applied to reach the goals of energy efficiency and low emissions exhaust aftertreatment system for heavy duty vehicles. The system is based on four technological advances: Thermoelectric materials for heat recuperation, catalytic reduction of NO x over innovative catalyst substrates using hydrocarbons from the fuel and H 2 from a high efficiency fuel reformer, and particulate filtration over a porous metal filter.

3 An illustration of how the individual components can be connected in an integrated system. KTH APU Fuel Reformer H 2 TYK EGR Thermoelectric heat recovery Heat exchanger Inlet KRT Exhaust Metal powder DPF KCK Lean NOx Catalyst

4 The E4 Mistra Project targets Fullfil very low emission levels 1. NO X : 0.1 g/kwh 2. PM : g/kwh 3. without an increase in CO 2 emissions Phase 1( ) was focused on fossil diesel, phase 2 ( ) includes also methanol and bio-diesel

5 Emission legislation and project goal PM (g/kwh) 0.15 On Road US On Road EU On Road Japan EU-II 95/96 US EU-III 00/ Japan NLT 05 US 07 EU-IV 05/06 Project goal US 10 EU-VI 13/ EU-V 08/ NO x (g/kwh) 7.0

6 Programme sub-projects and participants Catalytic reduction of NOx: Competence center of catalysis (KCK), Chalmers University of Technology Reformer systems for hydrogen production: Chemical Engineering and Technology, Royal Institute of Technology (KTH) Sintered metal powder filters: Höganäs AB Thermoelectric materials: Applied surface chemistry (TYK), Chalmers University of Technology CFD for heat exchangers: Chemical Reaction Engineering (KRT), Chalmers University of Technology Thermoelectric generators for power generation: Termo-Gen AB Heat exchangers for thermoelectric generator Alfa Laval AB System integration: Volvo Group Trucks Technology, Advanced Technology & Research (AT&R)

7 Catalytic reduction of NOx:

8 LNC Lean NOx catalysis Continuous addition of reductant (HC-SCR) Cu-zeoliter Ag/Al 2 O 3 Pt

9 Methods for manufacturing Ag/Al 2 O 3 catalysts Impregnation Sol-gel technique Thermal Freeze-dried impregnation sol-gel (thermally) sol-gel (freeze-dried)

10 NO x reduction (%) NO x reduction activity Different catalyst formulations Up-scaling of catalyst Influence of different fuels and H st generation LNC 2nd generation LNC C, 350 ppm CO250 C, 850 ppm CO300 C, 350 ppm CO300 C, 850 ppm CO Feed: 10 % O 2, 6 % CO 2, 5 % H 2 O, 1000 ppm H 2, 300 ppm n-octane, 200 ppm NO 400 CPSI monolith, GHSV 30,000 h-1, C/N=12.

11 Reformer systems for hydrogen production

12 Full-scale reformer with zoned catalysts

13 Catalyst manufacturing Reformer catalysts Layer:Rh(1.0)Pt(1.0) Layer: Rh(3.0) Layer 1: Rh(1.0)Pt(1.0) Layer 2: Rh(3.0) H 2 (vol %): 39 H 2 (vol %): 36 H 2 (vol %): 40 CH 4 (vol %): 0.12 CH 4 (vol %): 0.04 CH 4 (vol %):0.06 X (%): 99.0 X(%): 99.9 X (%): 99.9 Promoter: CeO 2 (10)La 2 O 3 (10). Support: δ-alumina Reaction condition: H 2 O/C= 2.4, O 2 /C=0.47, λ= 0.32 GHSV~17700 h -1,

14 Catalyst development focus on lower levels of precious metals

15 Main challenges for reformer development Using low PM loadings in reforming catalysts Reactant mixing in autothermal reforming Balancing exothermic and endothermic reactions Heat integration Controlling by-product formation, i.e. catalyst selectivity Catalyst stability Catalyst coking

16 Sintered metal powder filters

17 DPF Diesel Particulate Filters Reduce the particulate flow, typically > 99% Ceramic filters are most common Corderit, MgO-Al 2 O 3 -SiO 2 SiC Filtration through filter media and filter cake

18 Advantages of particulate filters based on sintered metal Less restricted design Higher heat conductivity Lower pressure drop less problems with ash loading Sintered porous metal powder sheet Corrugated solid (gas impermeable) sheet

19 Diesel Particulate filter (DPF) DPF system built and tested in singlecylinder engine bench Particulate filtration efficiency typically >99 % (by mass and number) Improved design in order to reduce bypass Pressure drop lower than comparable ceramic wallflow filters due to less ash storage on the filter walls and no channel plug formation at the end of the channels.

20 Thermoelectric Recuperation

21 Thermoelectricity T h U h - = Charge carrier (e.g. electron) T h > T c Higher thermal velocity for the electrons in the warm region results in a thermal diffusion of electrons to the cold region. charge density difference potential (voltage) difference Thermoelectric power (Seebeck coefficient): T c U c Thermoelectric Figure of merit : K: Thermal conductivity, s: Electric conductivity

22 Thermoelectric power generation N-type semi-conductors has negative electrones as charge carriers P-type semi-conductors has positive holes as charge carriers TE generator Characteristics Solid-state material Simple to install No moving parts High reliability Low maintenance Long life expectancy

23 Materials developed within E4 Mistra n-ba 8 Ga 16 Ge 30 Ba 8 Ga 16 Ge 30 sample from Chalmers

24 Material development at TYK Fundamental research Clathrate substrates BiTe nanostructured materials Doping of clathrate substrates with different materials (TiO 2, Au) HR TEM picture of p-ba 8 Ga 16 Ge 30 E4-Mistra sample

25 Material synthesis Raw materials Synthesis Ingot Ag, Pb, Te, Ge, Bi, Sb... Dopants Iodine, Na...

26 Powder TAGS85 Planetary mill Clathrate TYK Bi2Te3 Other materials Atomizing Ultrasound mill and rough

27 Compaction Powder Pre-compaction Material dependent final compaction of single material elements TAGS85 Clathrate,TYK Bi2Te3 PbTe Other or casting Press-sinter SPS Ultrasonic assisted compaction Warm compaction + Annealing

28 Elements M1 TAGS85 M2 M3 Clathrate TYK Bi2Te3 PbTe etc Coatings: Diffusion barrier layer Compatibility layer Sublimation barrier Solder binder layer Segmented elements

29 Modules and TEG Design and Calculation Produce couples and rows Assembly modules Thermal insulation Plate heat exchanger TEG Module enclosure Heat exchanger Integration Module design depends on operating temperature Assembly, test and verification

30 Sealing and test Sealing station Row- and module test

31 CFD of thermoelectric generators Main challenges: 1. Modelling of TEG material - Seebeck, Peltier, Thomson, Joule effects - Transient - General 2. Increase temperature drop over element - Good heat transfer on gas side - Low pressure drop - Design choices 1. Jets penetrating boundary layer 2. Heat Pipes 3. Extended surface 3. Avoid fouling - Smart design

32 Results parallell flow Temperature across the channal and TE-material Total potential in thermocouple

33 Temperature at TE-surface Jets hit direct on TE-material A thin plate, 0.35mm SS316 distributes the heat on surface More material such as a ceramic and small copper plates will increase the lateral heat transfer further and hence, the jets does not have to be located over the TE-elements.

34 System integration (Volvo s responsibility area in the programme) Programme coordination and management. Supports all sub-projects by providing specifications, boundary conditions and design ideas. Testing of individual components in Synthetic gas bench and engine lab. Build and integrated system from the individual part and test the complete system.

35 Progresses during 6 out of 8 programme years Cost effective NOx reduction catalyst which has the potential to reduce the NOx level to the set targets using bio-diesel together with hydrogen as reducing agents. Reliable Autothermal reactor design and catalytic material for Hydrogen production. Novel sintered metal powder diesel particulate filter which has a high particulate filtration efficiency and less pressure drop compared to conventional DPF systems. Development of thermoelectric materials to be used in the thermoelectric generator. Fundamental understanding of heat and mass transfer phenomenon in the thermoelectric generator developed with in the project. Several improvements in TE materials processing techniques to allow these materials to be utilized in TE device manufacturing and improve their performance. Successful integration of one TEG module developed within the project in a heat exchange demonstration system.

36 Planned activities during the programme last two years Further optimizations of the NOx reduction and reformer catalysts. Coating the DPF with catalytic material to optimize the soot oxidation and for exhaust gas system optimization purposes. Improve the efficiency of the thermoelectric materials. Develop a heat exchanges with integrated TEG to replace the Exhaust gas recirculation (EGR) unit in the truck exhaust gas system.

37 Acknowledgments Project participants Jonas Edvardsson Heije Westberg Jazaer Dawody Lennart Andersson Miroslawa Milh Hanna Härelind Ingelsten Hannes Kannisto Fredrik Gunnarsson Anders Palmqvist Rickard Heijl Yi Ma Daniel Cederkrantz Ronnie Andersson Olle Högblom Lars J. Pettersson Xanthias Karatzas Moa Ziethèn Granlund Per-Olof Larsson Fredrik Andreasson Special thanks to Mistra and the Swedish Energy Agency for the Financial support