Pressure-Actuated Fan Backflow Preventer for Multi-Fan Arrays
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Solution Overview
Problem
Conventional backflow preventers in air handling systems reduce the efficiency of fans due to additional complexity and the need for strong airflow to overcome gravitational forces, disrupting air flow and requiring additional structures or mechanisms.
Innovation Solution
A backflow preventer with a main body and movable doors that attach to fans, allowing air to flow only when pressure differential is present, eliminating the need for gravity or additional closing mechanisms, and enhancing fan efficiency by funneling air towards the inlet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gravity actuated backflow preventers are used, then backflow prevention function is achieved, but fan efficiency decreases due to requiring strong airflow to overcome gravitational force
Solution Approach 1:
The patent replaces the gravity-based mechanical system with a pressure differential-based system. The doors are actuated by air pressure differences rather than gravitational force, eliminating the need for fans to overcome the weight of dampers. This substitution resolves the contradiction by maintaining backflow prevention while removing the efficiency penalty associated with gravity actuation.
Solution Approach 2:
The invention uses pneumatic pressure differential to actuate the doors. When a fan fails, the pressure difference across the backflow preventer causes the doors to close automatically, preventing backflow without requiring mechanical gravity-based mechanisms. This pneumatic approach eliminates the gravitational force resistance that reduces fan efficiency.
2Reliability
If manually operated or electric motor actuated backflow dampers are used, then backflow prevention is achieved, but device complexity increases due to additional parts and structure
Solution Approach 1:
The backflow preventer is designed to be self-actuating through pressure differential. The system automatically closes the doors when backflow conditions occur, eliminating the need for manual operation or electric motor actuators. This self-service mechanism reduces device complexity while maintaining reliable backflow prevention functionality.
Solution Approach 2:
The invention extracts and eliminates the complex actuation mechanisms (manual operators, electric motors, springs, and counterweights) from conventional backflow preventers. By using only the essential pressure differential principle, the design achieves backflow prevention with minimal parts and structure.
3Reliability
If conventional backflow preventers are installed, then backflow prevention is achieved, but airflow disruption occurs reducing fan efficiency
Solution Approach 1:
The doors in the backflow preventer are designed to be dynamic rather than fixed, opening freely during normal operation and closing only when pressure differential indicates backflow conditions. This dynamic design minimizes disruption to airflow during normal fan operation while providing automatic protection when needed.
Solution Approach 2:
The system prepares for potential backflow conditions by having doors that can quickly close in response to pressure changes. The design anticipates backflow scenarios and has the capability to prevent them before they cause system issues, while maintaining unrestricted airflow during normal operation.
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 solution increases fan static efficiency by at least 3% and reduces noise by approximately 10 dBA, while preventing backflow without disrupting airflow, as the doors move based on pressure differential, maintaining system operation even if one fan fails.
Implementation Method 1
The doors are movable between the open position and the closed position by a pressure differential between the inlet area and the discharge area
Data Source
AI summary
A backflow preventer for use in a multiple fan array system that draws air from an inlet area and expels it into a discharge area includes a main body defining an open front end and an open rear end and is adapted for attachment to a fan of the fan array system adjacent an inlet of the fan. Doors are attached to the main body and configured for movement between an open position in which air is permitted to enter through the open front end and a closed position in which the doors block the open front end and air is prevented from entering through the open front end. The doors are movable between the open position and the closed position by a pressure differential between the inlet area and the discharge area. The doors in the open position form a tapered intake passageway that funnels air into the fan.