Decomposition Tube Mesh Device for Reductant Spray Interception

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Solution Overview

Problem

Conventional exhaust treatment systems for work vehicles face issues with reductant deposits forming in the decomposition tube, leading to reduced efficiency and flow characteristics due to temperature differences causing liquid reductant to impinge on surfaces and sublime into solid deposits.

Innovation Solution

The exhaust treatment system incorporates a decomposition tube with a mesh device that intercepts the reductant spray, ensuring it passes through and mixes with the exhaust before reaching the housing wall, enhancing atomization and evaporation, and a catalyst device to reduce NOx emissions, thereby preventing solid deposits and improving efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If liquid reductant is sprayed into the decomposition tube, then NOx reduction efficiency is improved, but solid deposits form on housing walls due to temperature differences causing liquid reductant to impinge and sublime

Engineering Contradiction:

ImproveNOx reduction efficiencyVSAvoidsolid deposits

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

A mesh device is introduced as an intermediary element between the reductant spray nozzle and the decomposition tube housing wall. The mesh device intercepts liquid reductant droplets that would otherwise impinge on the housing wall, allowing them to evaporate and mix with the exhaust stream instead of sublimating into solid deposits. This mediator resolves the contradiction by providing a temporary holding structure that enables complete vaporization before contact with the housing surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the physical state parameters of the reductant by controlling its temperature and pressure conditions. By optimizing the spray parameters and utilizing the heat from the exhaust stream, the liquid reductant is transformed into a vapor phase before reaching the housing wall, preventing the temperature differential that causes sublimation and solid deposit formation while maintaining effective NOx reduction.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If reductant spray is delivered directly into the exhaust flow path, then atomization is enhanced, but liquid reductant impinges on housing walls before complete evaporation

Engineering Contradiction:

Improveatomization qualityVSAvoidcomplete evaporation

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The mesh device serves as an intermediary structure that captures atomized droplets and provides extended surface area for evaporation. This allows the reductant to maintain its atomized state while gaining additional time and surface area for complete vaporization, resolving the contradiction between achieving fine atomization and ensuring complete evaporation before housing wall contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If mesh device is added to intercept reductant spray, then solid deposits are prevented, but device complexity increases

Engineering Contradiction:

Improvesolid deposits preventionVSAvoiddecomposition tube structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The mesh device utilizes a porous or perforated structure that provides numerous small surfaces for droplet interception and evaporation. This porous configuration achieves effective solid deposit prevention through its high surface-area-to-volume ratio, minimizing the need for additional complex components while maintaining the protective function.

Inventive Principle:

Principle #31Porous materials

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration effectively reduces or eliminates solid deposits, enhancing the atomization and evaporation of reductant, improving the efficiency of NOx reduction and maintaining or reducing emission levels while minimizing backpressure and reductant usage.

Implementation Method 1

enhancing atomization and evaporation

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

enhancing atomization and evaporation

Methodology Applied

Scientific EffectAtomization:

Implementation Method 3

a catalyst device fluidly coupled to receive the mixture of the reductant and the exhaust from the decomposition tube and configured to reduce NOx in the exhaust with the reductant

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 4

reduce NOx in the exhaust with the reductant

Methodology Applied

Scientific EffectChemical reaction:

Implementation Method 5

temperature differences causing liquid reductant to impinge on surfaces and sublime into solid deposits

Methodology Applied

Scientific EffectSublimation: Sublimation

Data Source

PatentUS10519832B2Decomposition tube for exhaust treatment systems

Publication Date: 2019.12.31 DEERE & CO

AI summary

A decomposition tube for an exhaust treatment system includes a housing with a housing wall that defines an exhaust flow path for exhaust; a reductant delivery mechanism coupled to the housing and having a nozzle configured to deliver a spray of reductant into the exhaust flow path; and a mesh device with a mounting element mounted on the housing wall and a mesh basket secured to the mounting element proximate to the nozzle to enclose and intercept the spray such that effectively all of the reductant passes through the mesh basket and into the exhaust flow path prior to impinging on the housing wall.