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Table 5.2 |
Comparison of Characteristics of Metallic and Ceramic Monolith Catalyst Substrates |
| Characteristics |
Metallic Monolith |
Ceramic Monolith |
Geometric Data |
|
| Wall thickness, mm |
0.02 - 0.04 |
0.06 -0.20 |
| Range of cell density , cells / cm2 |
16 - 186 |
16 - 186 |
| OFA (uncoated) for 62 cells / cm2, % cross section |
89- 91 |
67 -75.0 |
| area |
3.2 |
2.4-2.8 |
| GSA (uncoated) for 62 cells / cm2, m2/l |
|
|
Physical Data |
|
| Thermal conductivity, W/m.ºK |
14-22 |
0.1-0.8 |
Specific Heat capacity, kJ/kg.ºK |
0.4- 0.5 |
0.75-1.05 |
Density, g/cm3 |
7.4 |
2.2-2.7 |
| Coefficient of thermal expansion, 1/ºK |
15 |
1 |
Maximum short duration operating temperature, ºC |
1275-1375 |
1400 |
Maximum continuous operating temperature, ºC |
900-1150 |
1200 |
| Mass (105.7 mm dia. x 98 mm length) 62 cells / cm2, g |
680 |
340 |
Metallic monoliths have the following advantages compared to the ceramic monoliths:
- Higher mechanical strength
- High thermal conductivity and faster warm-up
- Higher flow area and lower pressure drop
- Higher tolerance to high temperature spikes
- Higher conversion efficiency
- Smaller size
- No special housing is required.
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