Heat Flux Sensor Thermal Conductor Design

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Solution Overview

Problem

Temperature and heat flow measurements in industrial processes are prone to errors due to ambient temperature fluctuations and process temperature differentials, especially in short thermowells, which affect the accuracy and repeatability of measurements.

Innovation Solution

A heat flux sensor with a thermally conductive rod attached to a heat flux sensor capsule, which directs heat flow from the hot end to the cold end, reducing spacing sensitivity and improving response time, and using multiple temperature-sensitive elements with a high thermal conductivity material like copper for accurate heat flux calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a short thermowell is used for heat flux measurement, then the device complexity is reduced and installation is easier, but measurement precision deteriorates due to ambient temperature fluctuations and process temperature differentials

Engineering Contradiction:
Improvethermowell structureVSAvoidtemperature measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

A thermally conductive rod is introduced as an intermediary element between the hot end and cold end of the sensor capsule. This rod acts as a thermal bridge that directs heat flow through the sensor elements, ensuring accurate temperature gradient measurement despite the short thermowell length and external temperature fluctuations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple temperature-sensitive elements are used to improve measurement precision, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improveheat flux measurement accuracyVSAvoidsensor capsule structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple temperature-sensitive elements (hot end and cold end elements) are merged onto a single thermally conductive rod structure. This integration allows the sensor capsule to maintain multiple measurement points while using a unified thermal conduction path, thereby improving heat flux measurement accuracy without proportionally increasing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Temperature

If thermal grease is used to improve heat transfer, then heat transfer improves, but manufacturing precision deteriorates due to difficulty in controlling element placement and thermal grease distribution

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidelement placement accuracy
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical/chemical method of using thermal grease for heat transfer with a solid thermally conductive rod structure. This substitution eliminates the need for precise thermal grease application and distribution, thereby improving manufacturing precision while maintaining effective heat transfer from the hot end to the cold end through the rod's high thermal conductivity.

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

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 measurement accuracy and repeatability by maintaining a uniform temperature gradient across the sensor elements, allowing for precise process fluid temperature estimation and reducing the impact of external influences.

Implementation Method 1

A heat flux sensor with a thermally conductive rod attached to a heat flux sensor capsule, which directs heat flow from the hot end to the cold end

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

using multiple temperature-sensitive elements with a high thermal conductivity material like copper for accurate heat flux calculations

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3762695B1Heat flux sensor with improved heat transfer
Publication Date: 2024.04.17 ROSEMOUNT INC
  • EP3762695B1 patent drawingFigure 1
  • EP3762695B1 patent drawingFigure 2A~2B
  • EP3762695B1 patent drawingFigure 3A~3C

AI summary

A sensor capsule (300) for a heat flux sensor includes a hot end (304) and a cold end (302). The sensor capsule (300) includes a thermal conductor (310) extending from the hot end (304) toward the cold end (302), and a plurality of temperature sensors (312, 354) coupled to the thermal conductor (310) at different distances from the hot end (304).