Pulsed Combustible Gas Sensor for Species Identification
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Solution Overview
Problem
Conventional combustible gas sensors face challenges such as measurement errors due to ambient temperature, humidity, and pressure changes, as well as catalyst deactivation by poisons, which affect their accuracy and power consumption, and require long response times for detecting combustible gases.
Innovation Solution
A combustible gas sensor with a first sensing element that periodically cycles between a temperature above the combustion temperature of analytes and a temperature at which the catalyst is inactive, using electronic circuitry to determine gas species and concentration, and optionally includes a compensating element and filter to minimize interference and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensing element is continuously heated to combustion temperature, then the sensor can continuously detect combustible gases, but power consumption increases and response time is prolonged
Solution Approach 1:
The sensing element is heated periodically in pulses rather than continuously. The controller activates the heating element in periodic cycles, allowing the sensor to reach combustion temperature for detection then cool down, reducing overall power consumption while maintaining detection capability through repeated cycling.
Solution Approach 2:
The sensing element is pre-heated to combustion temperature before gas detection begins. By establishing the high temperature state in advance during the pulse cycle, the sensor is ready for immediate gas detection when the pulse occurs, eliminating the need for continuous heating and reducing power consumption.
2Productivity
If the sensing element is continuously heated to combustion temperature, then gas detection can proceed without delay, but response time for detecting combustible gases is prolonged
Solution Approach 1:
The sensor operates in periodic pulse cycles where the sensing element is rapidly heated to combustion temperature during the pulse, enabling quick detection. The periodic nature allows the system to cycle through heating and cooling, achieving fast response times while reducing the duration of high-power operation.
Solution Approach 2:
The heating element's temperature is dynamically adjusted through periodic pulsing rather than maintained at a static high temperature. This dynamic operation allows the sensor to rapidly reach operating temperature for detection, then cool down, achieving fast response times while reducing overall energy consumption and improving detection speed.
3Measurement precision
If a compensating element is added to minimize environmental interference, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The compensating element is integrated into the same sensor housing and gas flow path as the sensing element. Both elements share the same environmental exposure and heating/pulsing mechanism, allowing the compensating element to offset environmental effects on the sensing element without requiring separate, complex systems.
Solution Approach 2:
The compensating element is designed with different catalytic properties or temperature characteristics that allow it to respond differently to environmental factors. By carefully selecting the compensating element's properties, the system can offset the effects of temperature, humidity, and pressure changes on the sensing element, improving measurement accuracy through parameter modification rather than structural complexity.
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 approach reduces power consumption, improves response time, and enhances the accuracy of gas detection by analyzing dynamic output during cycling, allowing for early determination of gas concentrations and species identification before reaching stable output, while minimizing the impact of environmental factors and catalyst deactivation.
Implementation Method 1
a heating element in operative connection with the catalyst to heat the catalyst above a temperature to combust gas analytes of interest
Implementation Method 2
catalytic oxidation of combustible gases
Implementation Method 3
catalytic oxidation of combustible gases
Implementation Method 4
The oxidation catalysts may, for example, operate in the temperature range of 350-600° C. for methane detection. A platinum alloy is often used because of its large temperature coefficient of resistance, resulting in a large signal in target or analyte gas.
Data Source
AI summary
A combustible gas sensor including a first sensing element having a catalyst and a heating element and electronic circuitry in operative connection with the heating element of the first sensing element to change a temperature thereof between a temperature above a temperature to catalyze oxidative combustion and a temperature at which the catalyst is substantially inactive to catalyze oxidative combustion of a plurality of gas analytes of interest. The electronic circuitry being configured to determine a species of at least one of the plurality of gas analytes of interest from a first, dynamic output of the combustible gas sensor while the temperature of the first sensing element is changing. The electronic circuitry further being configured to determine a concentration of the species from a second output of the combustible gas sensor.