Building airflow measuring system and method
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Solution Overview
Problem
Current airflow measuring systems in buildings lack accuracy, particularly at low flow rates, and interfere with air duct flow, impacting occupant comfort and energy efficiency.
Innovation Solution
A mass airflow measuring device with a main air passageway, first and second channels, and a sample channel, equipped with a mass airflow sensor that outputs a non-linear signal, which is processed to provide a linear and averaged airflow signal, integrated with HVAC systems for precise airflow control and energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional airflow measuring structures are used, then airflow measurement is achieved, but measurement accuracy deteriorates and interference with air duct flow increases
Solution Approach 1:
The invention extracts the measurement function from the main airflow path by using a separate sample channel that branches off to draw a portion of the airflow. This allows the main air passageway to remain unobstructed while the mass airflow sensor measures a representative sample, thereby maintaining measurement accuracy without interfering with the primary airflow.
Solution Approach 2:
The sample channel acts as an intermediary between the main air passageway and the mass airflow sensor. It selectively extracts a portion of the airflow for measurement while allowing the majority of the air to flow uninterrupted through the main passageway, thus mediating between the need for accurate measurement and the need to minimize flow interference.
2Measurement precision
If traditional airflow measuring structures are used, then airflow measurement is achieved, but measurement accuracy at low flow rates deteriorates
Solution Approach 1:
The invention changes the measurement parameters by using a mass airflow sensor that measures mass flow rate directly rather than relying on differential pressure measurements. This approach provides superior accuracy at low flow rates because mass flow measurement is less susceptible to errors from minor pressure fluctuations and maintains reliability across a wider range of flow conditions.
3Loss of information
If non-linear airflow signal is output by the mass airflow sensor, then measurement information is captured, but signal processing complexity increases
Solution Approach 1:
The invention replaces complex mechanical signal conditioning with electronic/digital processing. The mass airflow sensor outputs a non-linear signal that is processed using floating-point mathematics and averaging algorithms in a processing unit, substituting simple mechanical linearization with more flexible computational methods that can accurately handle non-linear relationships while maintaining system manageability.
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
Enables real-time, precise measurement of airflow and temperature, allowing controlled temperature adjustments and significant energy savings by minimizing interference with air duct flow and improving measurement accuracy at low flow rates.
Implementation Method 1
a selectively heated wire, with the housing having an inlet aperture and an exit aperture where airflow enters the housing through the inlet aperture, passes over the wire, and exits through the exit aperture
Implementation Method 2
airflow enters the housing through the inlet aperture, passes over the wire
Data Source
AI summary
A mass airflow measuring device includes an air passageway and a body positioned in the passageway. The body includes a peripheral section including a first channel, a sample section located radially inward of the peripheral section, and including an inlet port and a support section connecting the sample section to the peripheral section. The support section includes a second channel which communicates at a first end with the inlet port and at a second end with the first channel. A mass airflow sensor is mounted to the body.