Flame Pipe Dent Geometry for Heat Exchange With Low Flow Resistance

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Solution Overview

Problem

Existing flame pipes in fired heat exchangers do not effectively intensify heat exchange while maintaining low flow resistance for combustion gases.

Innovation Solution

A flame pipe with a circular cross-section featuring inward dents on its walls, where each dent has convergent surfaces positioned transversely or slantly with respect to the pipe axis, and pairs of dents differ in depth, arranged along the pipe length in various orientations to enhance turbulence while controlling flow resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If flame pipes are fitted with devices to turbulise the combustion gases, then heat exchange efficiency is intensified, but flow resistance increases

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidflow resistance
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent applies asymmetry by creating dent pairs where the two dents in each pair have different depths. This asymmetric configuration generates turbulence in the combustion gas flow while the specific geometric arrangement maintains lower flow resistance compared to symmetric turbulising devices. The asymmetric dent depths create varied flow paths that enhance mixing and heat transfer without excessive pressure drop.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent implements local quality by positioning dent pairs at specific locations along the pipe length and varying the dent characteristics locally. Each dent pair is designed with specific depth differences and angular orientations suited to local flow conditions, creating targeted turbulence zones that enhance heat exchange at critical locations without uniformly increasing flow resistance throughout the entire pipe.

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If conventional dent configurations are used, then manufacturing is simplified, but heat exchange intensification is insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidheat exchange intensification
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies parameter changes by systematically varying the dent depth, angle, and spacing parameters to optimize heat exchange performance. The dent pairs feature different depths (asymmetric parameter configuration) and specific angular orientations relative to the pipe axis. These parameter variations enhance turbulence and heat transfer while the dents remain pressable into the pipe wall using conventional forming techniques, maintaining manufacturing feasibility.

Inventive Principle:
Principle #35Parameter changes

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

The designed geometry increases turbulence of combustion gases, thereby enhancing heat exchange efficiency while keeping flow resistance low, as demonstrated by various embodiments and drawings.

Implementation Method 1

The designed geometry of the pipe according to the invention ensures increased turbulence of the flow of the combustion gases

Methodology Applied
Scientific EffectTurbulence: Turbulence

Implementation Method 2

heat exchanger pipe of other-than-circular shape in cross-section... which intensify the heat exchange process

Methodology Applied
Scientific EffectHeat exchange: Convection

Data Source

PatentEP3526536B1Flame pipe of a fired heat exchanger
Publication Date: 2022.12.07 AIC SPOLKA AKCYJNA
  • EP3526536B1 patent drawingFigure 1~4
  • EP3526536B1 patent drawingFigure 5~7
  • EP3526536B1 patent drawingFigure 8~9

AI summary

The flame pipe of a fired heat exchanger basically circular in cross section, having at least two inward dents in its walls according to the invention is characterised in that each dent (2) has two surfaces (3, 4) which are not longitudinal to the axis of the pipe, and preferably positioned transversely or slantways with respect to the axis of the pipe (1) and convergent to each other towards the inside of the pipe (1).