Blower control system
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Solution Overview
Problem
Existing building ventilation systems face challenges in minimizing power consumption while preventing toxic vapors from contaminated ground from entering buildings, as they require continuous operation of exhaust blowers to maintain pressure below impermeable sub slabs, which can be inefficient and require complex control to adapt to varying environmental conditions.
Innovation Solution
A blower control system that monitors pressure drops across the sub slab at multiple points and adjusts blower speed based on real-time and long-term changes, using a progressive control algorithm to maintain a minimum pressure drop, ensuring effective vapor removal while optimizing power usage across different time scales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exhaust blower operates continuously to maintain pressure below the sub slab, then toxic vapors are prevented from entering the building, but power consumption increases
Solution Approach 1:
The blower control system dynamically adjusts the blower speed based on real-time pressure differential measurements. The system transitions from continuous operation at fixed speed to variable speed operation, where the blower motor speed is modulated to maintain the minimum required pressure differential while consuming less power. This resolves the contradiction by making the system adaptive rather than static.
Solution Approach 2:
The system implements a feedback control loop where pressure sensors continuously monitor the pressure differential across the sub slab, and this information is fed back to the controller which adjusts the blower speed accordingly. This closed-loop feedback mechanism ensures that the blower operates only at the necessary power level to maintain vapor prevention, eliminating unnecessary energy consumption while maintaining reliability.
2Use of energy by moving object
If the blower speed is reduced to minimize power consumption, then energy efficiency improves, but the pressure drop may become insufficient allowing vapor ingress
Solution Approach 1:
The feedback control system continuously monitors the pressure differential and adjusts blower speed to maintain the minimum required pressure drop. The controller compares the measured pressure differential against the target minimum value and modulates the blower motor speed to correct any deviations, ensuring that power reduction never compromises vapor prevention effectiveness.
Solution Approach 2:
The system dynamically responds to changing environmental conditions (such as wind, temperature, and soil moisture changes) by adjusting blower speed in real-time. This dynamic adaptation ensures that the pressure differential remains above the minimum threshold required for vapor prevention, even as operating conditions vary, thereby maintaining reliability while optimizing power consumption.
3Reliability
If multiple pressure sensors are deployed to monitor pressure drops at different locations, then vapor prevention reliability improves, but system complexity increases
Solution Approach 1:
The system divides the monitoring function into multiple independent pressure sensor locations under the sub slab. Each sensor independently monitors the pressure differential at its specific location, providing localized data that contributes to overall system reliability. This segmentation allows comprehensive monitoring without requiring a monolithic complex control system.
Solution Approach 2:
The control system is designed to handle multiple sensor inputs using a universal control algorithm that processes data from any number of pressure sensors. The same control logic and communication infrastructure serve both monitoring and control functions, reducing overall system complexity despite the presence of multiple sensors. The system can scale from one to many sensors without fundamental redesign.
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 effectively maintains a stable pressure drop across the sub slab, minimizing power consumption and preventing toxic vapor ingress, with the progressive control algorithm allowing for quick responses to sudden changes and gradual adjustments over longer periods, ensuring consistent performance from minutes to months.
Implementation Method 1
The pressure below the sub slab can be reduced by using an exhaust blower. The blower sucks air from underneath the sub slab and exhausts it away from the building. This reduces the pressure below the sub slab causing air to flow from the building down into the ground.
Implementation Method 2
The pressure drop is computed by measuring the pressure below the sub slab at different points, relative to a reference pressure above the sub slab.
Data Source
AI summary
A controller for controlling a system for mitigating the flow of vapors from contaminated soil into a building controls a blower pulling an exhaust from underneath the sub slab of the building and blowing the vapors away from the building. The blower is controlled by pressure sensors that measure the pressure drop across the sub slab. The sensors are monitored by the controller to make sure they all have a minimum pressure drop. If any of the sensors have an inadequate pressure drop, the blower speed is increased a small amount by the controller. If all of the sensors have adequate pressure drop, then the blower speed is decreased by a small amount. The controller then rechecks the pressure drops on a periodic basis and makes appropriate blower speed adjustments after each measurement.