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 system duct pressure, eliminating the need for direct power sources and allowing for constant airflow regulation, even in the absence of primary power, and enabling easy maintenance and installation.
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 across zones
Solution Approach 1:
The patent changes the parameter of airflow resistance at each terminal device independently using dampers. By adjusting damper positions at individual terminals rather than opening/closing terminals completely, the system maintains relatively constant duct air pressure while controlling ventilation to occupied areas, resolving the contradiction between energy savings and pressure stability.
Solution Approach 2:
The system uses pressure sensors to monitor duct air pressure and provides feedback to the control device. The controller adjusts damper positions in response to pressure fluctuations, maintaining stable airflow distribution across zones while limiting ventilation to occupied areas, thus achieving both energy savings and pressure stability.
2Stability of the object's composition
If central fan speed is controlled to prevent over or under-ventilation, then airflow distribution improves, but control complexity and cost increase
Solution Approach 1:
The patent segments the central ventilation system into individually controllable terminal devices, each with its own damper and control capability. This allows localized airflow adjustment at each terminal without requiring complex central fan speed control, simplifying the overall control system while maintaining stable airflow distribution across zones.
Solution Approach 2:
Each terminal device is equipped with its own control mechanism (damper actuator) that can independently regulate airflow. This self-service capability at the terminal level eliminates the need for complex centralized control of fan speed, reducing system complexity while achieving proper airflow distribution.
3Ease of operation
If VAV terminals with electrically powered control devices are used to control airflow at each zone, then airflow regulation capability improves, but system reliability decreases when power is lost
Solution Approach 1:
The patent introduces spring-loaded dampers as mechanical intermediaries that provide default airflow control without requiring electrical power. The springs maintain damper positions and provide fail-safe operation, ensuring airflow control reliability even when electrical power is lost, while still allowing for electrically assisted regulation when power is available.
Solution Approach 2:
The system incorporates spring mechanisms that are pre-loaded to provide default damper positioning and airflow control. This beforehand cushioning ensures that even if electrical power fails, the dampers maintain their positions and continue to regulate airflow, preserving system reliability without compromising regulation capability when powered.
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
The system ensures consistent airflow to occupied zones while reducing energy consumption by optimizing fan requirements and maintaining indoor air quality, adhering to building codes by providing on-demand airflow and passive regulation.
Implementation Method 1
the airflow regulator regulating airflow along the predetermined path when the damper is in the closed position
Implementation Method 2
a damper hingeably coupled to the housing for controlling airflow between the area and a fan or ventilator
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. Another embodiment shows a combination of a first constant airflow controller or regulator situated or mounted on a damper with a second constant airflow controller or regulator situated in a duct associated with the damper. In still another embodiment, a constant airflow controller or regulator is provided in a duct, and used in combination with a solid damper.