Heat Flux Sensor Transient Measurement for Faster Material Testing

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Solution Overview

Problem

Existing stationary measurement methods for heat flow require lengthy stabilization periods, leading to long measurement times and potential thermal aging of samples, especially for materials operating under variable conditions, which affects data comparability and reliability.

Innovation Solution

A transient measurement method using a heat flow sensor with a measuring surface in thermal contact with the sample, coupled with a heat sink and heat source, determines heat flux by measuring local temperature changes and considering the sensor's heat capacity, establishing quasi-steady-state conditions to reduce measurement time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If stationary measurement methods are used to ensure measurement accuracy, then measurement precision is improved, but measurement time increases significantly due to lengthy stabilization periods

Engineering Contradiction:
Improveheat flux measurement accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent transitions from stationary measurement to transient measurement, making the measurement process dynamic. By measuring heat flux during the transient phase before thermal equilibrium is reached, the method eliminates the need for lengthy stabilization periods while maintaining accuracy through proper mathematical evaluation of the transient temperature data.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the measurement parameter from steady-state temperature difference to transient temperature change rate. By measuring how temperature changes over time during the transient phase and using the heat capacity of the sensor, the method calculates heat flux without requiring the system to reach thermal equilibrium, thus reducing measurement time significantly.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If stationary measurement methods are used to ensure accurate heat flux determination, then measurement precision is improved, but sample thermal aging occurs due to prolonged measurement duration

Engineering Contradiction:
Improveheat flux measurement accuracyVSAvoidsample integrity and data comparability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent uses dynamic transient measurement instead of static stationary measurement. By completing the measurement during the transient phase before thermal equilibrium, the exposure time of the sample to elevated temperatures is minimized, preventing thermal aging and maintaining sample integrity while still obtaining accurate heat flux data.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent performs the measurement action during the transient phase before the harmful thermal aging effect has time to occur. By capturing the temperature change data during this preliminary phase and evaluating it mathematically, the method obtains accurate results without subjecting the sample to prolonged thermal stress that would cause degradation.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If stationary measurement methods are used to characterize materials under varying conditions, then measurement precision is improved, but productivity decreases due to repeated stabilization requirements

Engineering Contradiction:
Improveheat flux measurement accuracyVSAvoidmeasurement throughput
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent enables rapid sequential measurements by using transient measurement for each data point. Instead of requiring stabilization before each measurement, the method captures transient temperature changes and evaluates heat flux immediately, allowing multiple measurements under varying conditions to be performed in quick succession, thus dramatically increasing productivity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent maintains continuous measurement action without interruption for stabilization. By continuously recording temperature during the transient phase and evaluating heat flux from the temperature change rate, the method eliminates idle stabilization time between measurements, keeping the measurement process continuous and maximizing throughput.

Inventive Principle:
Principle #20Continuity of useful action

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

Accurately measures heat flux with significantly reduced time compared to stationary methods, allowing for rapid characterization of materials under varying conditions without thermal aging, maintaining measurement accuracy.

Implementation Method 1

a heat flow sensor with a measuring surface 14 that is in thermal contact with the sample 10

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the determined heat flow is adjusted as a function of the heat power delivered or absorbed due to the heat capacity of the heat flow sensor 20, 20'

Methodology Applied
Scientific EffectHeat capacity:

Implementation Method 3

a heat sink 26 and a heat source 24 are provided, wherein the heat flow sensor 20, 20' and the sample 10 are arranged between the heat sink 26 and the heat source 24

Methodology Applied
Scientific EffectThermal gradient: Temperature Gradient

Implementation Method 4

a heat flow passes from the heat source 24 to the heat sink 26

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP4682520A1Method for transient measurement of a heat flux
Publication Date: 2026.01.21 DEUTSCHES ZENTRUM FÜR LUFT UND RAUMFAHRT E V
  • EP4682520A1 patent drawingFigure 1
  • EP4682520A1 patent drawingFigure 2A~2b
  • EP4682520A1 patent drawingFigure 3A~3B

AI summary

Method for transient measurement of a heat flow using a heat flow sensor with a measuring surface in contact with a sample, a heat source and a heat sink, wherein the heat flow sensor and the sample are arranged between the heat source and the heat sink, wherein the heat flow at the measuring surface is determined, wherein, to determine the heat flow at the measuring surface, the heat flow measured by the heat flow sensor is adjusted depending on the heat power emitted or absorbed due to the heat capacity of the heat flow sensor, wherein the measurement result in the steady state can be deduced from the measured values ​​of several measurements with different temporal temperature change rates.