Exhaust Stack Cooling via Mixing with Cooling Air

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Solution Overview

Problem

Skid steer machines face challenges in managing high exhaust temperatures during diesel particulate filter regeneration, which poses risks to operators and bystanders due to the compact design and limited space for exhaust aftertreatment systems.

Innovation Solution

The solution involves mixing exhaust gas with cooling air from a blower fan in a high temperature zone surrounding the exhaust stack outlet, using a cooling package positioned above the diesel particulate filter, to reduce the temperature of the fluid mixture below 200 degrees Celsius, thereby cooling the exhaust gases effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If exhaust aftertreatment systems are installed in skid steer machines, then particulate matter emissions are reduced, but exhaust temperatures become excessively high posing risks to operators and bystanders

Engineering Contradiction:

Improveparticulate matter emissionsVSAvoidexhaust temperature risk

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

Cooling air is introduced as an intermediary substance that mixes with hot exhaust gases in the exhaust stack. This cooling air acts as a mediator to transfer heat away from the exhaust stream, reducing the temperature of the exhaust plume without interfering with the diesel particulate filter regeneration process. The cooling air is drawn from the engine compartment and directed into the exhaust stack through strategically positioned openings.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If a diesel particulate filter is packaged within the engine compartment, then space is optimized, but heat management becomes more difficult

Engineering Contradiction:

Improveengine compartment spaceVSAvoidheat management

Core Design Contradiction:

Volume of moving objectVSTemperature

Solution Approach 1:

The cooling air intake openings are strategically positioned in specific locations within the engine compartment to optimize heat management. The openings are located to draw cooling air from regions that are naturally cooler and to direct it toward the exhaust stack where it is most effective. This localized approach to cooling air intake ensures efficient heat management while maintaining the compact packaging of the diesel particulate filter within the engine compartment.

Inventive Principle:

Principle #3Local quality

3Temperature

If cooling air is mixed with exhaust gas in the exhaust stack, then exhaust temperature is reduced, but the mixing process requires precise control of airflow

Engineering Contradiction:

Improveexhaust gas temperatureVSAvoidairflow control system

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The system utilizes the natural buoyancy and flow characteristics of the exhaust gases and cooling air to achieve effective mixing without requiring complex active control mechanisms. The cooling air is introduced at a position where it naturally mixes with the hot exhaust plume through turbulence and diffusion. The high temperature differential between the cooling air and exhaust gases creates natural flow patterns that facilitate mixing, eliminating the need for sophisticated airflow control systems while still achieving effective temperature reduction.

Inventive Principle:

Principle #25Self-service

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 approach effectively cools the exhaust gases to safe temperatures, reducing the risk of high temperature exposure for operators and bystanders, while maintaining efficient regeneration of the diesel particulate filter, even during active regeneration events.

Implementation Method 1

Exhaust gas exiting the exhaust stack outlet is mixed with the cooling air exiting the cooling package outlet in a high temperature zone surrounding the exhaust stack outlet to form a fluid mixture, and a temperature of the fluid mixture at a perimeter of the high temperature zone is below 200 degrees Celsius

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS8869516B2Method of mixing exhaust gas exiting an exhaust stack outlet with cooling air exiting a cooling package outlet and machine using same

Publication Date: 2014.10.28 CATERPILLAR SARL

AI summary

A machine includes an internal combustion engine disposed within an engine compartment and supported on a machine frame. An exhaust stack has an inlet fluidly connected to an exhaust manifold of the internal combustion engine and an outlet in fluid communication with ambient air. A diesel particulate filter is disposed along the exhaust stack. A cooling package includes at least one heat exchanger and a blower fan. The blower fan is configured to blow cooling air from the engine compartment sequentially through the at least one heat exchanger and an outlet of the cooling package. Exhaust gas exiting the exhaust stack outlet is mixed with the cooling air exiting the cooling package outlet in a high temperature zone surrounding the exhaust stack outlet to form a fluid mixture, and a temperature of the fluid mixture at a perimeter of the high temperature zone is below 200 degrees Celsius.