Combustion Device Mass Flow Sensor Placement for Condensation Control

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Solution Overview

Problem

Condensation occurs on mass flow sensors in combustion devices due to moist air, leading to potential short-circuiting and inaccurate measurements, and existing solutions like heating or using pressure sensors incur additional costs or limitations.

Innovation Solution

The mass flow sensor is arranged within a side channel that is partially located within the feed channel, maintaining the same temperature as the fluid, and the side channel is designed with a homogeneous temperature and vapor pressure distribution to prevent condensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a heating device is installed to prevent condensation on the mass flow sensor, then condensation prevention is improved, but device complexity and operational costs increase

Engineering Contradiction:
Improvecondensation on mass flow sensorVSAvoidadditional heating component
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The mass flow sensor is nested within the side channel, which itself is integrated into the feed channel structure. This nested arrangement allows the sensor to be positioned in a location where the existing feed channel walls provide thermal protection, eliminating the need for separate heating devices while preventing condensation.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The feed channel structure itself provides the thermal protection needed to prevent condensation on the mass flow sensor. The walls of the feed channel act as a thermal barrier, using the existing system structure to protect the sensor without requiring external heating components or additional energy input.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If the mass flow sensor is placed in the side channel, then flow rate measurement is improved, but condensation risk increases

Engineering Contradiction:
Improveflow rate measurementVSAvoidcondensation on sensor
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The side channel is designed with specific local qualities - its walls are positioned and dimensioned to create a thermal barrier that protects the mass flow sensor from condensation while still allowing the channel to serve its flow measurement function. The local geometry of the side channel within the feed channel provides targeted protection where needed.

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If pressure sensors are used instead of mass flow sensors, then condensation problems are reduced, but flow rate measurement capability is lost

Engineering Contradiction:
Improvecondensation issuesVSAvoidflow rate measurement
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The side channel acts as an intermediary structure that allows the mass flow sensor to be positioned in a protected environment. This intermediary arrangement enables the sensor to measure flow rate while the side channel walls provide thermal protection, solving both the measurement need and the condensation problem simultaneously.

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

Prevents condensation on the mass flow sensor, ensuring stable flow rate measurements without additional heating components or operational costs, while maintaining consistent flow behavior.

Implementation Method 1

the mass flow sensor (13) is located within the walls that delimit the feed channel (11) on the outside... the fluid in the supply channel (11) and the side channel (24) have the same temperature... the mass flow sensor (13) has the same temperature as the fluid in the supply channel (11) and as the side channel (24)

Methodology Applied
Scientific EffectTemperature equilibrium:

Implementation Method 2

the side channel (24) and the supply channel (11) are arranged in a volume with a homogeneous temperature distribution... the side channel (24) and the supply channel (11) are arranged in a volume with a homogeneous distribution of the partial pressure of the water vapor

Methodology Applied
Scientific EffectHomogeneous temperature distribution:

Implementation Method 3

The dew point temperature is a function of the relative humidity and/or the partial pressure of the water vapor. p D in a dry fluid, for example air

Methodology Applied
Scientific EffectDew point:

Data Source

PatentEP4306912B1Combustion device with mass flow sensor
Publication Date: 2025.10.29 SIEMENS AG
  • EP4306912B1 patent drawingFigure 1
  • EP4306912B1 patent drawingFigure 2
  • EP4306912B1 patent drawingFigure 3

AI summary

Combustion device with mass flow sensor. Combustion device comprising a burner (1), a side channel (24), and a feed channel (11); wherein the side channel (24) includes an inlet, an outlet, and a mass flow sensor (13) located between the inlet and the outlet of the side channel (24); wherein the mass flow sensor (13) is configured to detect a signal corresponding to a flow rate (15) of a fluid through the side channel (24); wherein the mass flow sensor (13) is flush with the inner wall of the side channel (24) or projects into the side channel (24); wherein the side channel (24) comprises a first section and a second section; wherein the first section of the side channel (24) is different from the second section of the side channel (24); wherein the first section of the side channel (24) includes the mass flow sensor (13); and wherein the first section of the side channel (24) projects into the feed channel (11).and wherein the first section of the side channel (24) projects into the supply channel (11) such that the mass flow sensor (13) is arranged within the supply channel (11).