Gas Viscosity Sensor Using Thin Membrane and LTCC Integration
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Solution Overview
Problem
Existing gas viscosity sensors are costly to manufacture, difficult to produce in a compact and reliable form, and struggle to provide accurate measurements in chemically aggressive environments, especially for mass applications related to natural gas combustion optimization.
Innovation Solution
A gas viscosity sensor comprising a signal processing circuit and a sensor element with a gas pressure generating system and differential pressure measuring system, featuring a thin membrane with a heat-sensitive resistor and heat sink, integrated into a ceramic substrate using LTCC technology, which measures time-dependent membrane displacement to correlate with gas viscosity and Wobbe index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gas viscosity sensors are used, then measurement capability is achieved, but manufacturing cost is high and device complexity is increased
Solution Approach 1:
The patent combines the pressure generating system, pressure measuring system, and signal processing circuit into a single integrated sensor device. The measuring chamber with membrane, heating element, and pressure sensor are merged into one compact unit, eliminating the need for separate equipment and reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The sensor device performs multiple functions within a single system: the heating element generates pressure changes, the membrane responds to pressure variations, the pressure sensor measures the changes, and the circuit processes signals to determine viscosity. This multi-functionality reduces the number of separate components needed and simplifies the overall measurement system.
2Measurement precision
If conventional gas viscosity sensors are used, then measurement capability is achieved, but manufacturing cost is high
Solution Approach 1:
By integrating all measurement functions into a single sensor device with shared components, the patent reduces the total number of parts that need to be manufactured and assembled. This consolidation lowers manufacturing costs while maintaining measurement precision through the coordinated operation of the integrated components.
Solution Approach 2:
The sensor uses the gas being measured as part of the measurement process itself - the gas flows through the measuring chamber and its own viscosity properties directly affect the membrane displacement and pressure changes. This eliminates the need for separate calibration standards or reference materials, simplifying manufacturing and reducing costs.
3Measurement precision
If conventional gas viscosity sensors are used, then measurement capability is achieved, but reliability in chemically aggressive environments is poor
Solution Approach 1:
The patent uses a thin membrane as the sensing element that directly interacts with the gas. This thin film structure allows for careful material selection that can resist chemical corrosion while maintaining the sensitivity needed for precise viscosity measurement. The membrane's flexibility also allows it to respond accurately to pressure changes without being damaged by aggressive gases.
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 provides a compact, reliable, and cost-effective sensor capable of accurately measuring gas viscosity and correlated parameters like density and Wobbe index, suitable for chemically aggressive environments, with improved manufacturing efficiency and long-term reliability.
Implementation Method 1
a heat-sensitive resistor positioned or the this membrane, and opposed thereto a heat sink
Implementation Method 2
a heat-sensitive resistor positioned or the this membrane, and opposed thereto a heat sink
Implementation Method 3
an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which the viscosity is to be determined, the inlet-outlet channel or orifice having dimensions adapted to provide resistance to the outflow and inflow of gas
Data Source
Figure 1~6
Figure 2
Figure 3
AI summary
A gas viscosity sensor comprises a signal processing circuit and a sensor element, including a gas pressure generating system and a differential pressure measuring system in fluid communication therewith, the differential pressure measuring system comprising a measuring chamber (14) bounded by a thin membrane (28), an inlet-outlet channel or orifice interconnecting the measuring chamber to a source of gas for which the viscosity is to be determined, the inlet- outlet channel or orifice having dimensions adapted to provide resistance to the outflow and inflow of gas in the measuring chamber, and a membrane displacement sensor (32) adapted to measure a time dependent displacement of the membrane due to pressure variations in the measuring cavity.