Helical Ceramic Heating Resistor for Compact Fluid Heating Elements

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Solution Overview

Problem

Existing electrical heating elements for fluids, particularly air, face inefficiencies in heat transfer due to small surface area relative to size, high maintenance needs, and costly production of silicon carbide ceramics, leading to labor-intensive constructions prone to contamination and wear.

Innovation Solution

A compact electrical heating element featuring a ceramic heating resistor with two open helical surface bodies coiled without contact, an electrically insulating tubular element, and a composite material of molybdenum disilicide and feldspar, optimized for efficient heat transfer and reduced thermal stress, allowing for automated manufacturing and lower operational temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a tubular resistance element with thin walls is used, then mechanical strength is improved and energy dissipation is enhanced, but the surface area effective for heat transfer remains small

Engineering Contradiction:
Improvemechanical strengthVSAvoidheat transfer surface area
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The patent transitions from a conventional tubular geometry to a helical coil geometry. This dimensional change allows the heating element to achieve a significantly larger surface area within a compact volume, enabling effective heat transfer to the fluid while maintaining structural integrity through the coiled configuration

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

2Loss of energy

If the cross section of fluid flow is only slightly larger than the resistance element, then heat transfer to the fluid is effective, but the device is not adaptable to different flow conditions

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidadaptability to different flow conditions
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent employs a flexible helical coil structure that can dynamically adapt to different fluid flow conditions. The coil configuration allows the heating element to effectively transfer heat to fluids with varying flow rates and cross-sectional areas, maintaining efficiency across diverse operating conditions without requiring a precise match between element size and flow channel

Inventive Principle:
Principle #15Dynamics

3Temperature

If silicon carbide ceramics are used for the heating resistor, then high temperature resistance is achieved, but production costs increase significantly

Engineering Contradiction:
Improvehigh temperature resistanceVSAvoidproduction cost
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The patent replaces expensive silicon carbide ceramics with a composite material consisting of molybdenum disilicide (MoSi2) particles embedded in a feldspar matrix. This composite achieves comparable high-temperature resistance and mechanical strength at significantly lower production costs, as both materials can be sintered at similar temperatures and the feldspar provides a cost-effective binding phase

Inventive Principle:
Principle #40Composite materials

4Ease of operation

If traditional helical heating wires are drawn into ceramic tubes by hand, then the heating element can be assembled, but labor intensity and contamination risk increase

Engineering Contradiction:
Improveassembly capabilityVSAvoidautomation of manufacturing
Core Design Contradiction:
Ease of operationVSExtent of automation

Solution Approach 1:

The patent merges the heating function and structural support into a single integrated ceramic component. The MoSi2-feldspar composite heating resistor is formed as a self-supporting structure that can be directly inserted into the ceramic tube without manual wire drawing, enabling automated manufacturing and eliminating contamination risks associated with hand assembly

Inventive Principle:
Principle #5Merging (Combining)

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 solution enhances heat transfer efficiency, reduces maintenance, and lowers production costs by using a compact, efficient ceramic heating resistor design with a composite material that withstands high temperatures and minimizes thermal stress, resulting in a longer service life and improved heat distribution.

Implementation Method 1

the heating resistor being produced by sintering at least one ceramic raw material having green body is produced, has an electrically insulating component and an electrically conductive component... the electrically conductive component is accommodated

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

heating a fluid, preferably air, with at least one tubular element through which a fluid flows or can flow

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

through which a fluid flows or can flow

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

a composite material of molybdenum disilicide and feldspar, optimized for efficient heat transfer and reduced thermal stress, allowing for automated manufacturing and lower operational temperatures

Methodology Applied
Scientific EffectThermal stability of refractory materials: Refractory Material

Implementation Method 5

the heating resistor being produced by sintering at least one ceramic raw material having green body

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3777473B1Ceramic heating resistance, electrical heating element and apparatus for heating a fluid
Publication Date: 2021.11.24 LEISTER TECHNOLOGIES AG
  • EP3777473B1 patent drawingFigure 1~3
  • EP3777473B1 patent drawingFigure 4~7
  • EP3777473B1 patent drawingFigure 8~9

AI summary

The invention relates to a ceramic heating resistor (1) for arranging in a tubular element (8) of an electrical heating element (9) for heating a fluid, preferably air. The heating resistor (1) can be produced by sintering a green body having at least one ceramic raw material. The heating resistor (1) has an electrically insulating component and an electrically conductive component. The electrically insulating component forms a matrix, in which the electrically conductive component is held. The invention further relates to an electrical heating element (9) for heating a fluid, preferably air, comprising at least one tubular element (8), through which a fluid flows or can flow, and to a device (17, 19) for heating a fluid, preferably air, comprising at least one such heating element (9).