Mixing device

Abstract

 The invention relates to a mixing device providing an even distribution of a gas stream, which has a perforated pipe with a number of external deflectors attached to the pipe.

Description

[0001] To clean up emissions from diesel engines, (e.g. for vehicles such as trucks and cars, and stationary engines) it is known to use diesel particulate filters (DPFs) and Selective Catalytic Reduction (SCR). For either system to work reliably and effectively it is necessary that the gases are highly dispersed and are evenly distributed onto the catalyst or filter. Mixers can be used to aid dispersion of gases and liquids. However these mixers create pressure losses with consequent reduction in engine performance and fuel economy.

[0002] The objective of this disclosure is to create good gas flow diffusion and mixing with minimum pressure loss in within a minimum package space.

[0003] In a typical engine exhaust the flow diffusion and mixing device is placed within the exhaust pipe. For a typical heavy duty engine of 12 litres capacity the exhaust pipe diameter is 5 inches.

[0004] It could be shown by the applicant that improved flow diffusion and mixing and reduced pressure loss is achieved by having a perforated pipe with a number of external deflectors attached to the pipe to direct the flow towards the substrate front face. The defectors size and number is then optimized depending on the flow conditions and design of the after treatment assembly. The deflectors may be full rings or partial rings attached at different angle to the external of the perforated pipe.

[0005] This results in improved mixing and gas flow diffusion and the back pressure is reduced simultaneously. Thus the adverse impact on engine performance and fuel economy is reduced.

Figure 1: shows an example of the combined diffusion and mixer unit with guiding deflectors. Case 01.

Figure 2: shows an example of the diffuser and mixer unit without the deflectors as disclosed in XC7000159-D. Case 02.

Figure 3: shows an example of the diffuser and mixer unit with partial deflectors as disclosed in XC7000159-F. Case 03.

Figure 4: shows the CFD analysis performed on a suitable combined flow diffuser and mixer unit with full deflectors within a vehicle after treatment assembly. Case 01.

Figure 5: show the CFD analysis performed on a suitable combined flow diffuser and mixer unit with out deflectors within a vehicle after treatment assembly. Case 02.

Figure 6: shows the CFD analysis performed on a suitable combined flow diffuser and mixer unit with partial deflectors within a vehicle after treatment assembly. The deflectors in this case are semi-circular. Case 03.

Claims

1. A mixing device having a member with a plurality of openings.

2. A mixing device having at least one feature as disclosed in the specification and/or the drawings.

Drawing