Self-calibration of a ventilation system
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Solution Overview
Problem
Existing ventilation systems face challenges in accurately determining pressure losses, especially during initial commissioning and after prolonged use, due to unknown specific aeraulic network losses and potential duct clogging, which affects the control of extraction flow rates without relying on expensive flow sensors.
Innovation Solution
A self-calibration method for controlled mechanical ventilation systems that determines pressure loss coefficients in situ by controlling flow regulators and measuring flow rates and pressure differences, allowing for precise calculation of pressure losses and their storage for future reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive flow sensors are used to control extraction flow rates, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the flow measurement function from dedicated flow sensors and relocates it to the existing pressure sensor by utilizing pressure differential measurements across known resistance elements. This eliminates the need for expensive flow sensors while maintaining measurement capability through the relationship Q = sqrt(2*ΔP/(ρ*k)).
Solution Approach 2:
The patent introduces pressure sensors as intermediary devices that indirectly measure flow rates through pressure differential measurements. Instead of directly measuring flow with expensive sensors, the system uses pressure sensors to measure ΔP across known resistance elements, then calculates flow rate from the pressure differential using the derived relationship.
2Reliability
If pressure loss coefficients are determined during initial commissioning only, then device complexity is reduced, but reliability deteriorates due to duct clogging over time
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors pressure differentials and compares actual flow rates with target flow rates. When deviations are detected (indicating duct clogging or system changes), the system automatically adjusts flow regulator positions or fan speed to compensate, and can trigger recalibration procedures to update pressure loss coefficients.
Solution Approach 2:
The patent performs preliminary determination of pressure loss coefficients during commissioning to enable immediate operational control. Additionally, the system is designed to perform periodic or on-demand recalibration to update these coefficients, proactively maintaining accuracy before significant performance degradation occurs.
3Ease of operation
If flow regulators are adjusted without knowing pressure losses, then ease of operation is improved, but measurement precision of flow rates deteriorates
Solution Approach 1:
The patent replaces manual mechanical adjustment of flow regulators based on empirical estimates with an automated control system that uses pressure sensor measurements and computational algorithms. The control unit calculates required regulator positions based on measured pressure differentials, target flow rates, and stored pressure loss coefficients, then automatically adjusts regulators to achieve precise flow control.
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 precise determination and memorization of pressure loss coefficients, enabling the ventilation system to accurately calculate real-time pressure losses, reducing the need for expensive sensors and improving system efficiency and maintenance.
Implementation Method 1
a fan for extracting an air flow, characterized in that it determines in situ at least one pressure drop coefficient associated with each duct of the installation
Implementation Method 2
a flow regulator with adjustable passage opening for each air extraction or supply duct
Data Source
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AI summary
The invention relates in particular to a ventilation system comprising: - a central unit (2) with an air extraction or supply fan (1), - N air extraction or supply ducts (41, 42, 43), each connected to an air inlet or outlet of said central unit (2); - at least one air discharge or supply duct (8), and - a flow regulator (51", 52", 53") with an adjustable opening for each air extraction or supply duct (41, 42, 43). The system is characterized in that the central unit (2) includes self-calibration means capable of determining and storing in situ a pressure drop coefficient associated with each air extraction or supply duct (41, 42, 43).