Kitchen Exhaust Fire Detection With IR-Optical Sensor Fusion
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Solution Overview
Problem
Existing fire suppression systems in exhaust ventilation systems for cooking appliances fail to differentiate between flare-ups from regular cooking and actual fires, leading to unnecessary activation or failure to suppress fires due to reliance on fixed temperature thresholds and lack of consideration for exhaust temperature changes.
Innovation Solution
A system that uses a combination of infrared (IR) and optical sensors to detect radiant temperature fluctuations and patterns, distinguishing between normal cooking, flare-ups, and fires by processing signals with high and low pass filters, and activating a fire suppression mechanism only when a sustained fire is detected, while adjusting exhaust fan speed and damper positions based on cooking appliance status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed absolute temperature threshold is used for fire detection, then the system is simple to operate, but it cannot differentiate between flare-ups from regular cooking and actual fires
Solution Approach 1:
The system transitions from using a single fixed temperature parameter to using multiple parameters including rate of temperature change, absolute temperature thresholds, and duration of temperature elevation. This allows the system to distinguish between normal cooking fluctuations and actual fire conditions by analyzing how temperature changes over time rather than relying on a static threshold.
Solution Approach 2:
The system continuously monitors temperature and uses the rate of change as feedback to adjust detection sensitivity. When temperature rises rapidly (high rate of change), the system interprets this as a potential fire condition even if the absolute temperature hasn't reached the fire threshold yet, enabling earlier and more accurate fire detection.
2Productivity
If the exhaust flow rate is continuously adjusted based on cooking appliance status, then the exhaust ventilation efficiency is improved, but the system complexity increases
Solution Approach 1:
The exhaust flow rate is made dynamic and adjustable based on detected cooking appliance status. The system automatically modifies exhaust parameters in response to changing cooking conditions, transitioning from a static fixed-flow system to a dynamic adaptive system that optimizes ventilation efficiency for different cooking scenarios.
Solution Approach 2:
The control system integrates multiple functions including temperature monitoring, appliance status detection, fire detection, and exhaust flow control into a single multi-functional unit. This consolidation manages complexity by combining what would otherwise be separate systems into one coordinated controller.
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
Effectively differentiates between cooking activities and fire conditions, ensuring timely and accurate activation of fire suppression mechanisms, minimizing false alarms and ensuring efficient exhaust airflow management.
Implementation Method 1
receiving, at a control module, an exhaust air temperature signal representing a temperature of the exhaust air in a vicinity of the exhaust hood, the exhaust air temperature signal being generated by a temperature sensor
Implementation Method 2
receiving, at the control module, a radiant temperature signal representing a temperature of a surface of a cooking appliance that generates the exhaust air, the radiant temperature signal being generated by a radiant temperature sensor
Data Source
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AI summary
Systems, devices, and methods for determining whether a fire condition exists based on a status of a cooking appliance, and systems, devices, and methods for controlling an exhaust air flow rate in an exhaust air ventilation system based on the status of the cooking appliance. At least one sensor type generating a predefined signal is used to detect fire condition and appliance cooking state, the predefined signal being applied to a controller which differentiates, responsively the predefined signal, in combination with other sensor signals, at least two cooking states each of the cooking states corresponding to at least two exhaust flow rates which the controller implements in response to the controller's differentiation of the two states and which predefined signal is simultaneously used to differentiate a fire condition, in response to the differentiation of which, the same controller activates a fire suppression mechanism.