Recent Trends for Filter Development for Diesel Particulate Aftertreatment

Transcription

1 7 th International ETH-Conference on Combustion Generated Particles August 18 2, 23 Recent Trends for Filter Development for Diesel Particulate Aftertreatment A. Schäfer-Sindlinger, C.D. Vogt NGK Europe GmbH Germany S. Hashimoto, R. Matsubara, T. Hamanaka, F. Katsube and S. Miwa NGK Insulators Ltd., Japan Abstract: This paper will give an overview about the recent trend filter development for diesel particulate aftertreatment for passenger cars and heavy duty vehicles. The material development for passenger car diesel particulate filters lead to new materials like silicon carbide while for heavy duty applications still Cordierite plays a major role. However in the future Cordierite might also be used for passenger cars in 4 way catalyst system applications This paper will show the basic difference between both applications and describe the materials in terms of properties (material, back pressure aspects, filtration efficiency) and application on vehicles. Furthermore an outlook will be given on catalysed soot filters.

2 Recent Trends for Filter Development in Diesel Particulate Aftertreatment A. Schäfer fer-sindlinger,, C.D. Vogt NGK Europe GmbH S. Hashimoto, R. Matsubara,, T. Hamanaka,, F. Katsube and S. Miwa NGK Insulators Ltd. 7th International ETH-Conference on Combustion Generated Particles, Zurich, August 18-2, 23 1

3 Content Introduction Particulate Filter Applications Material Properties Pressure Drop of Cordierite and Si-SiC Filters Filtration Efficiency Regeneration of Particulate Filters Summary 2

4 Introduction Trend of Particulate Limits for Diesel Passenger Cars [g/km],9,8,7,6,5,4,3,2, Source: Automobilwoche, VDA Year Normalised, different test cycles Particulate limits tighten globally 3

5 Introduction Market Share Diesel Passenger Cars in Europe 8 6 [%] 4 2 Germany 2 Source: Automobilwoche, VDA Year EU Growing market share for diesel vehicles in EU 4

6 Particulate Filter Applications Passenger Cars - Higher SOF content - Max. back pressure high - Temperature level: 15-3 C - Lower NO content - Discont. regeneration Heavy Duty Vehicles - Lower SOF content - Max. back pressure low - Temperature level: 2-5 C - Higher NO content - Cont. regeneration targeted NO 2 regeneration possible with Heavy Duty Vehicles 5

7 Particulate Filter Applications Fuel Additive Systems - Fast regeneration - High exotherm - High ash deposition - High pressure drop - Filter cleaning necessary Catalysed Soot Filter (CSF) - Softer regeneration - No CO and HC peaks - Only oil ash deposition - Lower pressure drop over service life - No Filter cleaning needed CSF should reduce ash and back pressure 6

8 Passenger Car Soot Filter System EGR Cooler EGR Valve Common-Rail Fuel Injection DI Diesel Engine Intercooler Turbo Charger Inlet Air Exhaust DPF System Oxidation Catalyst Uncatalysed or catalysed Filter Possible diesel passenger car aftertreatment system 7

9 Heavy Duty Aftertreatment System Oxidation Catalyst (1) CO + 1/2 O 2 CO 2 (2) HC + O 2 CO 2 + H 2 O (3) NO + 1/2 O 2 NO 2 Source: Johnson Matthey Plc. Soot Filter (Catalysed or non catalysed) (1) 2 NO 2 + C CO NO Heavy duty application maybe combined with SCR 8

10 Cordierite and Si-SiC Filters Cd-DPF SiC-DPF Monolithic Segmented Coefficient of Thermal Expansion A-axis (x1-6 / o C: 4-8 o C) Cordierite (Cd)-DPF Material Properties Cd-DPF SiC-DPF.4-1. SiC-DPF 4 Thermal Conductivity (W/m K) 1 12 Major difference in design and material properties 9

11 NGK Material Properties of Cordierite Filters Material C 558 Std. Cordierite C 611 High Porosity Filter (w/o coating) Filter for CSF High Porosity Filter for CSF (high loading) 5µm 5µm 5µm Porosity [%] Mean Pore Size [µm] Therm. Conductivity [W/mK] CTE, A Axis [x 1 6 / C] 1, 1, 1, 1

12 NGK Material Properties of Si-SiC Filters NGK Materials Si-SiC Material for Fuel Additive Systems Si-SiC Material for Catalysed Filters (CSF) Si-SiC Material for Catal. Filters (CSF) (High Porosity) 1? µ m 1? µ m 1? µ m Porosity [%] Mean Pore Size [µm] Therm. Conductivity [W/mK] CTE, A Axis [x 1 6 / C] 4,

13 65DHC-611DHC-5Cordierite Filters Impact of Coating on Initial Pressure Drop 6 5 C-6 Uncoated 8 5 C-65 DHC-611 DHC-558 Coated Pressure Drop, kpa Air Flow Rate, Nm3/min Air Flow Rate, Nm3/min. Coating increases initial back pressure by ~ 1 % 12

14 Cordierite Filters Impact of Porosity on Pressure Drop with Soot 25 Before Coating C-65 DHC C-65 DHC DHC DHC-558 Pressure Drop, kpa After Coating 5 5 DPF : 5.66"Dx6"L, 12/3 Gas Flow Rate : 2.27Nm3/min Gas Temp. : 2deg.C NGK Soot Generator Amount of Soot Loading, g Amount of Soot Loading, g High porosity filters provide lowest pressure drop 13

15 Si-SiC Filters Impact of Porosity on Initial Pressure Drop Pressure Drop [ kpa] % Porosity, 2 µm catalysed 52% Porosity, 2µm catalysed Gas Flow [Nm3/min] 52 and 6 % Porosity uncatalysed Almost no impact with high porosity filters 14

16 Non Coated Si-SiC Filters Cell Structure, Porosity and Pressure Drop Pressure Drop [ kpa] % Porosity 15 mil/2cspi 52 % Porosity 15 mil/2 cpsi Soot Loading [g/l] 52 and 6 % Porosity 12 mil/3 cpsi With soot cell structure has an impact 15

17 Si-SiC Filters CSF Impact of Porosity on Pressure Drop with Soot Pressure Drop [ kpa] % Porosity catalysed 6% Porosity catalysed Soot Loading [g/l] 6% Porosity uncatalysed 52% Porosity uncatalysed High porosity filters advantageous for CSF 16

18 Engine Bench Pressure Drop Evaluation Experimental Conditions Engine and particulate filter Engine Type Common Rail Direct Injection Engine Displacement [L] 2, Filter size [inch] 5,66 x 6 Filter volume [L] 2,47 Test procedure Engine Speed [rpm] 15 (5) - 5 Sampling time per step [min] 6 Load Up to full load NGK Engine Bench with 2,l Common Rail DI Diesel Engine 17

19 Engine Bench Pressure Drop Evaluation Pressure Drop Test up to Full Load (1 g/l soot loading) Pressure Drop [kpa] Mass Flow [kg/h] % Porosity 15mil/2cpsi 6 % Porosity 12mil/3cpsi 52 % Porosity 12mil/3cpsi Engine Speed [rpm] High porosity and high surface filters advantageous 18

20 Filtration Efficiency of Cordierite Filters Non coated Cordierite Filters versus Soot Loading 1 Filtration Efficiency(%) C-65, 12mil/3cpsi 65 % Porosity DHC-611, 12mil/3cpsi 58 % Porosity Engine conditions: Speed : 2 rpm Torque : 5 Nm DPF In Temp. : C Air Flow Rate : Nm3/min Filter Size: D 129 x L 152 mm,5 1 1,5 2 Amount of soot loading(g/l) Already ~ 95 % efficiency at.2 g/l soot loading 19

21 Filtration Efficiency Non coated Si-SiC Particulate Filters 1 Filtration Efficiency (%) % Porosity 12 mil/3 cpsi 48 % Porosity 15 mil/2 cpsi Amount of Soot Loading (g/l) Filtration efficiency > 9 % at,1 -,2 g/l soot 2

22 Determination of the Filtration Efficiency Scanning Mobility Particle Sizer Sheath Flow: 3 l/min Sample Flow:.3 l/min DMA CPC Dilution Air R/B Thermodenuder Sampling Dilution Air Heater Flow rate adjustment Exhaust Engine Sample Dilution Tunnel PM Filter Inlet DPF Outlet Exhaust Gas Sample area: 2 C Tunnel area: 8 C Sample: 35 C Dilution Ratio: 5 : 1 21

23 Filtration Efficiency of Catalysed Si-SiC DPF Comparison of the Filtration Efficiency by SMPS Filtration Efficiency [%] Soot Loading: -.1 g/l Catalysed DPF 52% Porosity Catalysed DPF 6% Porosity Particle Size [nm] Filtration Efficiency [%] Soot Loading: g/l Catalysed DPF 52% Porosity Catalysed DPF 6% Porosity Particle Size [nm] Already > 9 % efficiency at.1 g/l soot loading 22

24 Filtration Efficiency of Cordierite Filters Impact of Soot Loading x35,1 g/l Soot Loading x35,3 g/l Soot Loading x35,5 g/l Soot Loading x245 x245 x245 After soot cake build up filtration efficiency > 95 % 23

25 Filtration Efficiency and Porosity Filtration Efficiency of catalysed Si-SiC Filters Soot Amount: g/L Soot Amount: -.1g/L Filtration Efficiency [%] Catalysed DPF 52% Porosity Catalysed DPF 6% Porosity Mean Pore Size before Cat. Coating [µm] Soot loading has an impact on filtration efficiency 24

26 Regeneration with Fuel Additives DPF Temperature ( C) Pressure Drop (mbar) inlet 4 Sample: SiC 5.66 Dx1 L, 1g/L soot loading in out :5 5:34 6:17 7: 7:43 Time (mm:ss) CATA IN DPF IN DPF OUT T4 T5 T6 T7 T8 Post Injection Pressure Drop 5 Engine: 2.L DI, 25ppm Ce additive High soot mass limits with Si-SiC materials 25

27 Regeneration with Catalysed Si-SiC Filters Engine: DI 2.L ( Common Rail) Conditions: 17 rpm x 95 Nm 1 min post injection 4 g/l soot 1 Regeneration Efficiency [%] Catalysed DPF 52% Porosity high washcoat loading Non catalysed DPF 52% Porosity DPF Inlet temperature 7 sec after Starting PI [ C] Improved regeneration efficiency with CSF 26

28 Summary Passenger cars discontinuous regeneration CRT and SCRT systems likely for heavy duty Low pressure drop with high porosity filters Filtration efficiency > 9 % from.1 g/l soot High heat mass and therm. conductivity favourable Good thermal shock resistance with Si-SiC filters High soot mass limits for Si-SiC filters Improved regeneration efficiency with CSF 27

29 Thank you very much for your attention! The Authors A. Schäfer fer-sindlinger,, C.D. Vogt S. Hashimoto, R. Matsubara, T. Hamanaka,, F. Katsube and S. Miwa wish to thank for submitting catalysts and catalysed soot filters (CSF) Johnson-Matthey Plc. for providing the cut-away of the CRT CRT TM is a Trademark of Johnson-Matthey Plc. 28

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