HVAC Zone Airflow Monitoring for Infiltration-Based Sensor Diagnostics
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Solution Overview
Problem
HVAC system zoning requires accurate air flow monitoring, but existing sensors may malfunction due to infiltration and exfiltration, leading to unreliable data and increased maintenance needs.
Innovation Solution
A method and control system that utilize first and second flow sensors to measure supply and return flows, determine infiltration and exfiltration components, and assess the operational state of the sensors, allowing for in-situ monitoring and reduced maintenance by recording temporal flow courses and detecting deviations indicative of sensor malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensors are used to detect air flow in HVAC zones, then air flow monitoring capability is provided, but sensor reliability deteriorates due to infiltration and exfiltration effects causing false readings
Solution Approach 1:
The system uses feedback by continuously monitoring both supply and return air flow measurements and comparing them against each other. The control system analyzes the relationship between supply flow (Q_supply) and return flow (Q_return) to detect deviations caused by sensor malfunction, infiltration, or exfiltration, and generates maintenance alerts when thresholds are exceeded.
Solution Approach 2:
The system performs self-diagnosis by using its own existing sensors to monitor its operational state. The control system automatically detects sensor fouling or malfunction by analyzing flow imbalances without requiring external inspection, and generates maintenance alerts autonomously based on predetermined thresholds.
2Measurement precision
If additional sensors or monitoring components are added to detect sensor malfunction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control system performs multiple functions using existing components: it controls HVAC operations, monitors air flow measurements, detects sensor malfunction, identifies infiltration/exfiltration events, and generates maintenance alerts. The system is designed to be universal, handling both normal HVAC control and diagnostic monitoring without requiring separate dedicated hardware.
Solution Approach 2:
The system monitors its own operational state using its existing sensors and control logic. No additional monitoring hardware is required because the control system autonomously analyzes its own performance data to detect sensor degradation, maintaining measurement precision while avoiding increased complexity.
3Loss of information
If sensor fouling is not detected, then device complexity remains low, but loss of information occurs due to unreliable air flow data
Solution Approach 1:
The system continuously feedbacks on the quality of its own measurements by comparing supply and return flow data. When deviations exceed predetermined thresholds, the system automatically generates maintenance alerts, ensuring that unreliable data is identified and flagged without requiring manual intervention or complex additional hardware.
Solution Approach 2:
The control system autonomously monitors its own operational state and data quality. It automatically detects sensor fouling, identifies infiltration/exfiltration events, and generates maintenance alerts without external assistance, minimizing information loss while maintaining appropriate automation levels.
Data Source
AI summary
A method of monitoring an air flow in a zone (1) of an HVAC system (10) is described, the zone (1) comprising a supply port (11) and a return port (12), a first flow sensor (111) configured to measure a supply flow (ϕ1) through the supply port (11), and a second flow sensor (121) configured to measure a return flow (ϕ2) through the return port (12), the method comprising: recording by a control system (20, 20′) the supply flow (ϕ1) measured by the first flow sensor (111) and the return flow (ϕ2) measured by the second flow sensor (121); determining by the control system (20, 20′) an infiltration and exfiltration component (ϕinf/exf), using the supply flow (ϕ1) and the return flow (ϕ2) recorded by the control system (20, 20′); and determining by the control system (20, 20′) an operational sensor state of at least one of the first flow sensor (111) and the second flow sensor (121), using the supply flow (ϕ1), the return flow (ϕ2), and the infiltration and exfiltration component (ϕinf/exf).