Design and Implementation of an Infrared Radiant Source for Humidity Testing

Area of Science:

• Physics
• Engineering
• Environmental Science

Background:

• Accurate humidity measurement is crucial for various environmental and industrial applications.
• Existing humidity sensors can be limited by temperature sensitivity and environmental interference.
• Developing novel sensing principles is essential for advancing humidity metrology.

Purpose of the Study:

• To present a novel method for measuring relative humidity (RH) using thermal emissivity.
• To design and validate a grooved radiant source for humidity sensing applications.
• To investigate the performance of the system under varying environmental conditions.

Main Methods:

• A grooved radiant source operating in the 8–12 μm far-infrared band was developed.
• A Monte-Carlo model was employed to analyze the thermal radiation characteristics of the V-grooved surface.
• Heat pipe technology ensured an isothermal radiant surface, and fuzzy-PID control enhanced stability.
• Experimental validation was performed using a scanning radiant thermometer.

Main Results:

• The grooved radiant source demonstrated uniform thermal radiation suitable for humidity testing.
• The system operated effectively in the temperature range of 5–95 °C and 20–90% RH.
• The fuzzy-PID control system mitigated heat inertia and environmental interference, ensuring robust performance.
• A calibration method for humidity testing using the radiant source was successfully explored.

Conclusions:

• The proposed method provides a viable and precise approach for humidity measurement based on thermal emissivity.
• The developed radiant source and control system offer robust and accurate performance across a broad operational range.
• This technology has the potential to improve humidity monitoring in diverse environments.