Thermal Diffuser for Accurate Weld Zone Temperature Measurement

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Solution Overview

Problem

The challenge in nuclear power plant maintenance is accurately measuring the temperature of weld zones during local stress-relieving heat treatments, as existing methods struggle to precisely measure the skin temperature, leading to deviations from required temperature ranges.

Innovation Solution

A temperature measurement assembly is introduced, featuring a thermal diffuser with a temperature sensor housed in a receiving cavity, positioned between the heating device and the treatment surface, to accurately measure the temperature of the weld zone, reducing thermal gradients and ensuring precise temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature sensor is placed directly on the treatment surface to measure temperature, then measurement precision is improved, but the sensor is exposed to high thermal gradients and direct heat from the heating device causing measurement errors

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidthermal gradient exposure to sensor
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A thermal diffuser is introduced as an intermediary component between the heating device and the temperature sensor. The diffuser spreads and homogenizes the thermal field, creating a more uniform temperature distribution in the measurement region. This mediator protects the sensor from direct exposure to high thermal gradients while still allowing accurate temperature measurement of the treatment surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the temperature sensor is housed in a receiving cavity within the thermal diffuser, then protection from thermal gradients is improved, but the device complexity increases

Engineering Contradiction:
Improvethermal gradient protectionVSAvoidmeasurement assembly structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The temperature sensor is nested within a receiving cavity that is itself integrated into the thermal diffuser structure. This nested arrangement provides thermal protection for the sensor while maintaining a compact overall structure. The cavity is formed as part of the diffuser body rather than being a separate component, which helps minimize the increase in device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Manufacturing precision

If local stress relief heat treatments are applied to weld zones, then manufacturing precision is improved, but accurate temperature measurement becomes difficult due to thermal gradients

Engineering Contradiction:
Improveheat treatment temperature controlVSAvoidskin temperature measurement
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The thermal diffuser acts as a mediator that distributes heat uniformly across the measurement region, eliminating steep thermal gradients that plague conventional direct measurement methods. This allows accurate temperature measurement during local stress relief heat treatments of weld zones, enabling precise control of the manufacturing process.

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 solution allows for precise temperature measurement and control during heat treatments, ensuring the weld zone reaches the required temperature range, thereby maintaining the integrity and mechanical characteristics of the assembly while adhering to technical manufacturing references.

Implementation Method 1

a thermal diffuser configured to be interposed between the heating device and a measurement region of the treatment surface such that the measurement region is heated by the heating device through the thermal diffuser

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a temperature sensor housed in a receiving cavity arranged in the first surface to be in contact with the measurement region and to measure the temperature of the measurement region

Methodology Applied
Scientific EffectTemperature sensing: Thermocouple

Data Source

PatentEP4113081A1Assembly for measuring the temperature of a surface of an object during the performance of a heat treatment, assembly and method for heat treatment
Publication Date: 2023.01.04 FRAMATOME SA
  • EP4113081A1 patent drawingFigure 1
  • EP4113081A1 patent drawingFigure 2
  • EP4113081A1 patent drawingFigure 3

AI summary

The measurement assembly includes a thermal diffuser (20) configured to be interposed between a heating device (10) and a measurement region (8A) of a treatment surface (8) such that the measurement region (8A) is heated by the heating device (10) through the thermal diffuser (20), the thermal diffuser (20) comprising a first surface (22) intended to be applied against the measurement region (8A) and a second surface (24) intended to be covered by the heating device (10), and a temperature sensor (28) housed in a receiving cavity (32) provided in the first surface (22) to be in contact with the measurement region (8A) and to measure the temperature of the measurement region (8A), while being covered by the thermal diffuser (20).