Double-Pipe Heat Exchanger Inner Pipe Corrugation Without Rolling

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Solution Overview

Problem

The existing methods for manufacturing double-pipe heat exchangers with corrugated portions for enhanced heat transfer are costly and time-consuming, primarily due to the need for continuous rolling processes.

Innovation Solution

A method involving the use of a cored bar and a metal movable claw to form corrugated portions on an inner pipe by radially pressing it inward, allowing for efficient formation of outward and inward protrusions in a predetermined range, thereby increasing the heat transfer area without requiring expensive equipment or extrusion processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If grooves are formed by rolling using a grooving tool, then the heat transfer area is increased and heat exchange efficiency is improved, but the manufacturing apparatus becomes expensive and the manufacturing process takes a long time

Engineering Contradiction:
Improveheat transfer areaVSAvoidmanufacturing apparatus cost
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive, complex rolling equipment with simple, inexpensive forming tools (forming tool with pressing element and support tool). These simple tools can be easily manufactured and discarded, eliminating the need for costly rolling apparatus while achieving the same corrugated groove formation on the heat exchanger tube surface

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the complex mechanical rolling system with a simpler pressing and support mechanism. Instead of using a grooving tool that rolls along the tube surface, the invention uses a forming tool that presses the tube surface against a support tool, creating corrugated grooves through plastic deformation rather than rolling

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If grooves are formed by rolling, then the heat transfer area is increased, but the manufacturing process must be continuous and takes a long time

Engineering Contradiction:
Improveheat transfer areaVSAvoidmanufacturing time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs periodic action by moving the forming tool and support tool in alternating pressing and release cycles along the heat exchanger tube. The pressing element presses the tube surface to form corrugated grooves, then releases to allow the tube to elastic rebound, creating a rhythmic forming process that is simpler and faster than continuous rolling

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent divides the heat exchanger tube into multiple sections, with corrugated grooves formed in predetermined ranges rather than continuously along the entire tube length. This segmentation allows for more efficient manufacturing by focusing the forming process on specific areas that require enhanced heat transfer

Inventive Principle:
Principle #1Segmentation

3Manufacturing precision

If corrugated portions are formed in a predetermined range of the inner pipe, then the heat exchange efficiency is improved, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by forming corrugated grooves only in specific predetermined ranges of the heat exchanger tube where enhanced heat transfer is most needed. The forming tool and support tool are positioned to create corrugated portions in targeted sections rather than uniformly along the entire tube, optimizing heat exchange efficiency in critical areas while simplifying the overall manufacturing process

Inventive Principle:
Principle #3Local quality

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 method enables the rapid formation of corrugated portions on the inner pipe, improving heat exchange efficiency while using an inexpensive manufacturing apparatus, and allows for easy fixation of the inner pipe to the outer pipe without special treatment at the ends.

Implementation Method 1

forming the corrugated portion in a predetermined range of the inner pipe in the axial direction by pressing the inner pipe radially inward by the metal movable claw and plastically deforming the inner pipe

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP4056294B1Method for manufacturing double-pipe heat exchanger
Publication Date: 2023.12.20 NICHIRIN CO LTD
  • EP4056294B1 patent drawingFigure 1A~1B
  • EP4056294B1 patent drawingFigure 1C~1D
  • EP4056294B1 patent drawingFigure 2A~2B

AI summary

A method includes: an inner pipe insertion step of inserting an inner pipe 3 to between a cored bar 1 and a metal movable claw 2; a designated section corrugated portion formation step of forming a corrugated portion 3h (3a) in a first designated section 3a by pressing the first designated section 3a of the inner pipe 3 radially inward by the metal movable claw 2 and plastically deforming the first designated section 3a; a movable claw moving step of moving the metal movable claw 2 outward in the radial direction of the inner pipe 3; and an inner pipe moving step of moving a second designated section 3b that is the next designated section to between the cored bar 1 and the metal movable claw 2.