| 摘要 |
<p>The exhaust cooler (20) has a conical inlet (21), conical transition section (22) and intermediate tube bundle (23). The outlet integrates with the inlet of the storage catalyst (10). Injected engines are generally lean-burn, a storage catalyst removing NOx over intervals of 1-2 minutes. Normal operation for 1.3 seconds regenerates the catalyst, controlled by the engine management system. In this mode, temperature is kept below 800 degrees C by the cooling bundle, preventing thermal destruction of the storage catalyst. The unit is fully interchangeable between models. Combination of cooler outlet and catalyst inlet minimizes length and simplifies design. Tube size may be varied to adjust cooling area and to reduce noisy resonance effects. PREFERRED FEATURES:- The tube bundle surrounds a central zone. Conical sections each have a formation assisting flow, at the ends of the tube bundle. Tubes, in the bundle, have diverse cross-sections. The bundle is encased by a housing, in which coolant (e.g. air) circulates. The catalyst casing (11) and all conical sections (13,21,22) are made in one piece.</p> |
