High-Rise Vent Shaft Segmentation for Uniform Fire-Floor Airflow
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Solution Overview
Problem
Existing high-rise building ventilation systems face challenges in maintaining consistent airflow and preventing smoke ingress during fires, particularly due to height-dependent outflow conditions and complex control technologies, which can lead to incomplete evacuation scenarios.
Innovation Solution
The system incorporates an outflow shaft with a modified shaft effect, utilizing air direction and velocity sensors to regulate airflow independently of building height, ensuring homogeneous flow velocities and directions, and employs adjustable outflow devices and fans to maintain airflow within predetermined limits, regardless of floor height, using either positive or negative pressure systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fan is used to generate negative pressure in the outflow shaft, then air flow is created in the fire floor, but the flow speed on lower floors becomes lower than on upper floors due to increasing resistance with suction height
Solution Approach 1:
The outflow shaft is divided into multiple sections with individual adjustable outflow devices on each floor. This segmentation allows independent control of outflow conditions on each floor, enabling the system to compensate for height-dependent resistance variations and maintain uniform air flow speeds across all floors.
Solution Approach 2:
The outflow devices are made dynamically adjustable rather than fixed. Each outflow device can be independently opened or closed to modify the outflow cross-section, allowing the system to adapt to varying resistance conditions at different heights and maintain optimal air flow distribution.
2Productivity
If the outflow shaft geometry is optimized for upper floors, then outflow is improved there, but lower floors experience complete standstill of air flow
Solution Approach 1:
Each floor is equipped with its own adjustable outflow device that can be independently controlled. This local control capability allows the system to optimize outflow conditions for each specific floor location, compensating for the cumulative resistance effect of shaft geometry and maintaining adequate air flow speeds on lower floors while preserving outflow efficiency on upper floors.
3Reliability
If complex control technology is used to maintain pressure differentials, then smoke-free escape routes are achieved, but the control system becomes prone to failure and requires extensive wiring
Solution Approach 1:
The system uses the natural shaft effect (temperature-driven buoyancy) to generate air flow automatically without requiring complex active control. The heat from the fire naturally creates upward air movement in the shaft, and the adjustable outflow devices simply need to be opened to allow this natural flow to occur, significantly simplifying the control system while maintaining reliability.
Solution Approach 2:
The system converts the harmful heat from the fire into a beneficial force by utilizing the temperature difference to drive natural convection currents in the shaft. This thermally-driven natural flow replaces the need for complex mechanical control systems, reducing complexity while maintaining the smoke-free escape route function.
4Measurement precision
If pressure sensors are installed to monitor outflow conditions, then negative pressure formation is detected, but the control system becomes more complex and wiring requirements increase
Solution Approach 1:
The system incorporates simple feedback mechanisms through the adjustable outflow devices that respond to local conditions on each floor. Rather than using complex pressure sensors and centralized control, the system allows operators to adjust outflow openings based on observed conditions, providing sufficient feedback for safe operation without excessive complexity.
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
This approach simplifies control processes, reduces sensor and wiring requirements, and ensures consistent airflow across all floors, preventing smoke ingress into escape routes and ensuring effective evacuation by maintaining airflow without exceeding maximum values.
Implementation Method 1
According to the well-known barometric height formula, a pressure difference occurs between the top and bottom of a vertical shaft, i.e. also in the outflow shaft. This leads to a flow in the shaft if the shaft base and shaft head are not closed.
Implementation Method 2
For example, a suction effect should be able to occur, as is known from water jet pumps.
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a high-rise building comprising: - a number of n floors, - a stairwell which is connected to the individual floors via stairwell doors, - an antechamber for each floor, said antechamber being connected to the stairwell via one of the stairwell doors, - a vent shaft which has a geometrically open cross-sectional area of at least 0.6 sq. m and which has a shaft head above the highest floor and a shaft base below the ground floor (EG), - a motor-driven venting means at the shaft head, - a motor-driven venting device for each floor, the venting device being fitted between the usable area and the vent shaft and being normally closed, - a smoke detector for each floor, each smoke detector being fitted in the usable area, and - a controller, which is connected to the smoke detectors, the venting devices, and the venting means, and which in the event of a fire on a given floor activates the venting device of said floor and the venting means at the shaft head.