Virtual Flow Meter Calibration for HVAC Valve and Pump Systems
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Solution Overview
Problem
Current HVAC systems face challenges in accurately measuring airflow and water flow rates due to the impracticality of physical flow meters, which are hindered by space limitations and high installation costs, and virtual flow meters lack accurate calibration procedures and equipment models, leading to inaccuracies in energy performance evaluation.
Innovation Solution
A flow device system that determines airflow and water flow rates using valve, fan, and pump characteristic models, incorporating empirically-obtained stiction and deadband data to convert valve commands into actual positions, and employs a controller to alter valve positions and determine flow rates with improved accuracy, reducing the need for physical meters and simplifying calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical flow meters are installed to measure airflow and water flow rates, then measurement precision is improved, but device complexity and installation cost increase due to space requirements and infrastructure needs
Solution Approach 1:
The patent creates virtual copies of physical flow meters by using mathematical models and existing sensor data (temperature, pressure, humidity, equipment status) to calculate and estimate flow rates. Instead of installing actual physical meters, the system generates virtual measurements through computational algorithms that replicate the function of physical flow measurement devices.
Solution Approach 2:
The patent replaces mechanical/physical flow measurement systems with an information-processing system. Instead of using physical meters that require installation infrastructure, the system uses software algorithms, mathematical models, and data processing to determine flow rates, substituting mechanical measurement with computational analysis.
2Ease of operation
If virtual flow meters are used to avoid physical installation, then ease of operation is improved, but measurement precision deteriorates due to lack of accurate calibration procedures and equipment models
Solution Approach 1:
The patent implements feedback mechanisms where the virtual flow meter system continuously monitors multiple parameters (temperature, pressure, humidity, equipment status) and adjusts its calculations based on real-time data. The system uses feedback from various sensors and system states to refine flow rate estimates and improve measurement accuracy over time.
Solution Approach 2:
The patent changes the parameters used for flow measurement from direct physical flow detection to indirect parameter analysis. Instead of measuring flow directly, the system analyzes changes in temperature, pressure, humidity, and equipment operational parameters to infer flow rates, transforming the measurement approach from direct to indirect parameter-based measurement.
3Measurement precision
If multiple sensors are placed throughout the building system to obtain flow rate data, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes existing multi-functional sensors serve additional purposes. Temperature, pressure, humidity, and equipment status sensors that were originally designed for their primary functions are also utilized for virtual flow rate measurement. This multi-functionality approach allows the system to extract flow rate information from sensors already present in the HVAC system without requiring dedicated flow measurement devices.
Solution Approach 2:
The patent merges the flow measurement function with existing sensor networks and control systems. Instead of creating a separate flow measurement infrastructure, the system combines virtual flow metering with temperature sensing, pressure monitoring, humidity detection, and equipment status tracking into an integrated measurement and control platform.
Data Source
AI summary
Flow device systems for use in an HVAC system (“HVAC”) are described. The system may include a controller receiving sensor signals including differential pressure, valve commands, fan/pump speed, and fan/pump motor power signal from the HVAC. The controller transmits override valve commands for multiple valve positions of the valve and multiple speeds of the fan and pump. A characteristic curve may be determined from the signals provided from the HVAC and the measured flow rate at each valve position or fan/pump speed during transmission of the plurality of override valve commands for the valve positions of the valve and fan/pump speed for fan/pump operation frequencies. Virtual flow rate through the valve, fan or pump is determined using the characteristic curve. In addition, valve dynamic behavior is determined using valve stiction and valve stiction plus deadband. Valve commands are updated based on valve dynamic behavior and a valve characteristic curve.