Clamshell heat exchanger

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Solution Overview

Problem

Conventional heat exchangers face challenges in achieving high efficiency when dimensions are constrained, such as in space-limited furnace installations, making it difficult to recover heat effectively.

Innovation Solution

A clamshell heat exchanger design with a serpentine passageway and specific aspect ratio, featuring U-bends, seal regions, and a venturi inlet, formed from sheet metal halves, which allows for efficient heat transfer and compact installation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional heat exchanger designs are used with constrained dimensions, then installation space is reduced, but heat transfer efficiency deteriorates

Engineering Contradiction:
Improveinstallation spaceVSAvoidheat transfer efficiency
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent transforms the conventional heat exchanger geometry by extending the passageway in the depth direction rather than increasing height or width. This dimensional shift allows the heat exchanger to achieve sufficient heat transfer surface area and residence time within constrained vertical and horizontal spaces, thereby maintaining high heat transfer efficiency while reducing overall installation volume.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs serpentine (curved) passageways instead of straight channels, allowing the hot gas flow to follow a winding path through the heat exchanger. This curvature increases the effective heat transfer path length and surface area contact within a compact footprint, enabling high efficiency heat recovery without requiring large installation space.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Loss of energy

If heat exchanger efficiency is increased to achieve high heat recovery, then the device complexity increases, but manufacturing ease deteriorates

Engineering Contradiction:
Improveheat recovery efficiencyVSAvoidmanufacturing simplicity
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The patent divides the heat exchanger into two separate clamshell halves that can be manufactured independently using standard sheet metal forming processes. This segmentation allows each half to be produced using conventional manufacturing techniques, simplifying production while enabling the assembly of a complex serpentine passageway geometry that achieves high heat recovery efficiency when the halves are joined.

Inventive Principle:
Principle #1Segmentation

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 clamshell heat exchanger achieves an efficiency of at least 70% and enables subsequent heat recovery, resulting in an overall furnace efficiency of up to 90%, while maintaining a compact design suitable for constrained spaces.

Implementation Method 1

The passageway includes a venturi at an inlet

Methodology Applied
Scientific EffectVenturi effect: Venturi Effect

Implementation Method 2

A high-efficiency furnace typically employs several heat exchangers to warm an air stream passing through the furnace

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP2345844B1Clamshell heat exchanger
Publication Date: 2022.03.02 LENNOX IND INC
  • EP2345844B1 patent drawingFigure 1
  • EP2345844B1 patent drawingFigure 2
  • EP2345844B1 patent drawingFigure 3

AI summary

A clamshell heat exchanger includes a first clamshell half and a second clamshell half. When joined, the first and second clamshell halves form a passageway having an inlet and an outlet. The passageway has a height and a depth. A ratio of the height to the depth is about 0.5 or less. The heat exchanger has an efficiency of at least about 70%.