Condensing Heat Exchanger With Annular Gap to Prevent Soot Fouling

Solution Overview

Problem

Condensing heat exchangers in gas boilers face rapid deterioration due to soot and impurities entering the heat exchange zone, leading to fouling and reduced efficiency over time, which is difficult to remove and affects the constant heat exchange capacity.

Innovation Solution

The design features a casing with an annular gap between two walls, preventing soot and impurities from entering the heat exchange zone, and a helical gap with fins that direct combustion fumes for extended contact with the liquid, eliminating the need for a deflecting member and simplifying construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the gap is sized to optimize heat exchange efficiency, then heat transfer performance is improved, but soot and impurities can enter and cause fouling that deteriorates performance over time

Engineering Contradiction:

Improveheat exchange efficiencyVSAvoidheat exchange capacity stability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The heat exchanger is divided into two distinct zones: a first zone with a smaller gap optimized for heat exchange between combustion fumes and the hollow elongated member, and a second zone with a larger gap that prevents soot and impurities from reaching the heat exchange surfaces. This segmentation allows each zone to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A deflecting member is introduced as an intermediary element that redirects combustion fumes and prevents soot-laden flows from directly contacting the hollow elongated member. This mediator protects the heat exchange surfaces from fouling while maintaining the optimized gap dimensions for efficient heat transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a deflecting member is added to prevent soot entry, then fouling is reduced, but device complexity increases

Engineering Contradiction:

Improvefouling resistanceVSAvoidconstruction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The heat exchanger is divided into two distinct zones: a first zone with a smaller gap optimized for heat exchange between combustion fumes and the hollow elongated member, and a second zone with a larger gap that prevents soot and impurities from reaching the heat exchange surfaces. This segmentation allows each zone to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

3Duration of action of moving object

If the hollow elongated member is coiled in a helix, then heat exchange time is increased, but soot and impurities can contact and foul the surfaces

Engineering Contradiction:

Improveheat exchange contact timeVSAvoidsoot and impurity contamination

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The heat exchanger is divided into two distinct zones: a first zone with a smaller gap optimized for heat exchange between combustion fumes and the hollow elongated member, and a second zone with a larger gap that prevents soot and impurities from reaching the heat exchange surfaces. This segmentation allows each zone to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A deflecting member is introduced as an intermediary element that redirects combustion fumes and prevents soot-laden flows from directly contacting the hollow elongated member. This mediator protects the heat exchange surfaces from fouling while maintaining the optimized gap dimensions for efficient heat transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 maintains a constant heat exchange efficiency over time, enhances heat transfer, and simplifies assembly and cleaning, while preventing soot from contacting the heat exchanger components, ensuring prolonged performance and efficiency.

Implementation Method 1

achieve heat exchange between the combustion fumes and the liquid

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

heat exchange between the combustion fumes and the liquid

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

combustion fumes cross the gap between the adjacent turns in radial direction

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 4

Condensing heat exchanger for a gas boiler

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentEP2434227B1Condensing heat exchanger for a gas boiler

Publication Date: 2017.02.01 RIELLO

AI summary

A condensing heat exchanger for a gas boiler has a casing (3) for conducting combustion fumes; a hollow elongated member (4) for conducting a liquid, and which is coiled about an axis (A) to form a helix (5) which is housed inside the casing (3) and has a number of adjacent turns (12) and a helical gap (13); and a first combustion fume feed region (11) for feeding combustion fumes into the helix (5); the casing (3) having a first wall (6) extending about the axis (A) and the helix (5) and equipped with a first outlet (23) for the combustion fumes; and a second wall (7) extending about the first wall (6) and spaced apart from the first wall to form an annular gap (22) between the first wall (6) and the second wall (7), which has a second outlet (24) offset with respect to the first outlet (23).