Method and apparatus for passively controlling airflow
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Solution Overview
Problem
Existing central ventilation systems face challenges in efficiently controlling airflow to specific zones, leading to excessive energy consumption, poor indoor air quality, and failure to meet building code requirements due to fluctuations in duct air pressure and inadequate zone control.
Innovation Solution
A ventilation terminal system with an integral primary zone-controlled damper and pressure-independent flow control devices that regulate airflow using sensors and motors, allowing for constant airflow levels and reduced power requirements, and can operate without direct electric or pneumatic power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If terminal devices are opened and closed to limit ventilation to occupied areas, then energy consumption is reduced, but duct air pressure fluctuates causing uneven airflow distribution
Solution Approach 1:
The flow control device uses the duct pressure differential itself to drive the damper operation, eliminating the need for external power sources. The device automatically responds to pressure changes by allowing the pressure differential to open or close the damper, creating a self-regulating system that maintains stable airflow distribution while reducing energy consumption.
2Ease of operation
If VAV terminals with electrically powered control devices are used to control airflow at each zone, then airflow control capability is improved, but device complexity and power requirements increase
Solution Approach 1:
The invention extracts and eliminates the complex electrical control components (motors, sensors, power sources) from the terminal devices. Instead, it uses a simple mechanically operated damper that responds directly to duct pressure differentials, maintaining airflow control capability while dramatically reducing device complexity and power requirements.
Solution Approach 2:
The invention replaces the electrical/pneumatic control system with a purely mechanical system. The damper is operated by the duct pressure differential itself through a mechanical linkage, eliminating the need for electrical motors, sensors, and control electronics while maintaining the ability to control airflow at each zone.
3Productivity
If central fan speed is controlled to prevent over or under-ventilation, then overall ventilation balance is improved, but airflow amounts at each zone remain inconsistent
Solution Approach 1:
The invention divides the central ventilation system into independently controllable zones, each with its own flow control device. This segmentation allows each zone to be controlled individually based on its specific requirements, ensuring consistent airflow delivery to each zone while maintaining overall system ventilation balance.
Data Source
AI summary
A system and method for providing a substantially constant volume exhaust or ventilation air terminal system is shown for controlling exhaust and/or return airflow rates in a system having a central fan or ventilator. The system and method permits zone-by-zone or area-by-area airflow regulation or control in non-demand areas in response to a demand or call for ventilation in demand areas. In one embodiment, the system employs at least one constant airflow controller or regulator situated in a damper. In one embodiment, a terminal houses a plurality of sub-ducts each having an airflow regulator. At least one of the sub-ducts has a damper. When the damper is open, a maximum airflow through the terminal is a sum of maximum airflow permitted by the regulators.