Helical Steam Generator Bypass Duct Heat Recovery

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Solution Overview

Problem

Existing waste heat utilization devices in internal combustion engines face challenges in achieving high energy efficiency and cost-effective manufacturing, particularly in the design of steam generators, where heat transfer efficiency and compactness are crucial.

Innovation Solution

A steam generator design featuring a heat exchanger duct with a bypass duct, where the heat exchanger is arranged helically around the bypass duct, allowing for efficient heat transfer with low flow resistance and reduced risk of overheating, and incorporating a control element like a rotatable bypass flap for adjusting heat flow, along with a thermal insulation layer and coiled tubing for ease of maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the heat exchanger is arranged in a conventional configuration, then heat transfer efficiency can be achieved, but the device complexity and manufacturing costs increase

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The heat exchanger duct is arranged concentrically around the bypass duct, with the heat exchanger coils wrapped around the bypass duct. This nested configuration allows the heat exchanger to utilize the space around the bypass duct effectively, improving heat transfer efficiency while maintaining a compact and simple overall structure that reduces device complexity and manufacturing costs.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Volume of moving object

If the heat exchanger is designed for compactness, then space utilization improves, but heat transfer efficiency may deteriorate

Engineering Contradiction:
Improvesteam generator volumeVSAvoidheat transfer efficiency
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

The heat exchanger transitions from a planar arrangement to a three-dimensional helical configuration wrapped around the bypass duct. This dimensional change allows the heat exchanger to maximize surface area contact with the exhaust gas flow within a compact volume, achieving both compactness and high heat transfer efficiency simultaneously.

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

3Stability of the object's composition

If the bypass duct is positioned off-center, then structural stability improves, but flow resistance increases

Engineering Contradiction:
Improvestructural stabilityVSAvoidflow resistance
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The design accepts the asymmetric positioning of the bypass duct within the housing as a compromise, where the asymmetric layout provides structural stability and ease of installation, while the concentric arrangement of the heat exchanger around the bypass duct compensates for any flow resistance issues by ensuring uniform heat distribution.

Inventive Principle:
Principle #4Asymmetry

4Loss of energy

If the heat exchanger is tightly coupled to the bypass duct, then heat transfer efficiency improves, but risk of overheating increases

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidoverheating risk
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The bypass duct serves as an intermediary element between the exhaust gas flow and the heat exchanger. By positioning the heat exchanger around the bypass duct rather than directly in contact with the exhaust stream, the bypass duct mediates the heat transfer process, allowing efficient heat extraction while preventing direct exposure to excessive temperatures that could cause overheating.

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 design enhances energy efficiency, reduces production costs, and allows for a compact, maintenance-friendly steam generator system that effectively utilizes waste heat, improving the integration of waste heat recovery in internal combustion engines.

Implementation Method 1

a heat exchanger for transferring heat from the heating fluid to the working medium

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

a thermal insulation layer for thermally insulating the heat exchanger channel relative to the bypass channel

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP2815086B1Waste heat recovery device with a rankine cycle
Publication Date: 2017.10.04 EBERSPACHER EXHAUST TECH GMBH & CO
  • EP2815086B1 patent drawingFigure 1
  • EP2815086B1 patent drawingFigure 2
  • EP2815086B1 patent drawingFigure 3

AI summary

The invention relates to a steam generator (1) for a Rankine process, in particular for a waste-heat utilization device (37) of an internal combustion engine (36), preferably in a motor vehicle, comprising: a heat exchanger duct (2) in which a heat exchanger (3) is arranged, and a bypass duct (4) for bypassing the heat exchanger duct (2), wherein the heat exchanger duct (2) and the bypass duct (4) can, during operation of the steam generator (1), be traversed by a flow of a heating fluid, and wherein the heat exchanger (3) can, during operation of the steam generator (1), be traversed by a flow of a medium (47) to be evaporated. A compact design with high energy efficiency can be attained if the heat exchanger duct (2) encases the bypass duct (4).