A Universal Calibration Device for an Air Flow Sensor of the VAV Terminal Unit

Area of Science:

• HVAC systems
• Sensor technology
• Calibration techniques

Background:

• Accurate airflow measurement is critical for Variable Air Volume (VAV) terminal units.
• Existing calibration methods can be complex and require specialized equipment for different sensor types.

Purpose of the Study:

• To design and validate a novel, versatile calibration device for VAV terminal unit airflow sensors.
• To achieve intelligent, one-button calibration with high accuracy.

Main Methods:

• Development of a calibration device featuring multi-aperture air outlets and a movable flow rectifier.
• Integration of a Raspberry Pi for a high-performance GUI and control algorithm enabling intelligent calibration.
• Experimental calibration of airflow sensors across three different VAV terminal unit types.

Main Results:

• The developed device successfully calibrated airflow sensors with an accuracy of 5% after formula conversion.
• Identified the critical importance of maintaining specific, close distances between flow rectifiers and the VAV unit for accurate results.
• Demonstrated the device's capability to calibrate various VAV terminal unit airflow sensors without redesigning the calibration pipeline.

Conclusions:

• The new calibration device offers an accurate and efficient solution for VAV terminal unit airflow sensor calibration.
• Precise calibration is essential for establishing accurate airflow equations from differential pressure measurements.
• Optimal placement of flow rectifiers is crucial to minimize errors and ensure reliable airflow sensing.