Vented Dryer Fire Containment Using Cold Water Injection
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Solution Overview
Problem
Vented clothes dryer appliances face challenges in meeting the UL 2158 Dryer Fire Containment Standard due to their open air system, requiring an effective fire containment system that can be implemented with minimal structural changes.
Innovation Solution
A fire containment system using a cold water flow through a flexible hose connected to a heat-sensitive electromechanical switch, which activates upon detecting high temperatures to deliver cold water into the dryer tub to extinguish fires, with minimal modifications to the appliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fire containment system is added to a vented dryer, then fire safety is improved, but device complexity increases
Solution Approach 1:
The fire containment system merges multiple functions into a single integrated assembly: the water delivery hose provides water supply, the thermistor sensor detects temperature, the valve actuator controls water flow, and the heater box assembly serves both heating and fire suppression functions. This consolidation improves fire safety while minimizing the increase in device complexity by utilizing existing appliance components.
Solution Approach 2:
The heater box assembly serves dual purposes: normal operating heating during dryer cycles and fire suppression heating when activated by the thermistor. The water delivery system similarly serves both routine moisture removal and emergency fire containment. This multi-functionality allows the system to improve fire safety without adding entirely separate dedicated components.
2Ease of manufacture
If minimal structural changes are made to implement fire containment, then ease of manufacture is improved, but fire containment effectiveness may be compromised
Solution Approach 1:
The system performs preliminary actions by pre-positioning the water delivery hose within the heater box assembly and pre-configuring the thermistor sensor to monitor temperatures. The valve actuator is pre-connected to the water supply system. These preliminary arrangements enable rapid response to fire conditions while requiring minimal structural modifications to the existing dryer, thus maintaining ease of manufacture while ensuring fire containment effectiveness.
Solution Approach 2:
The thermistor sensor acts as an intermediary between the heating elements and the water delivery system, detecting temperature changes and triggering the valve actuator. The valve actuator serves as an intermediary between the control system and the water supply, converting electrical signals into mechanical valve operation. These intermediary components enable effective fire containment with minimal structural changes by mediating between detection and response functions.
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 contains and extinguishes fires within the dryer tub by delivering cold water, meeting fire safety standards with minimal alterations to the existing appliance design.
Implementation Method 1
cold water flow through a fire suppression fluid conduit and into an interior space of a tub of the appliance to contain and extinguish a fire burning within the interior space
Implementation Method 2
The electromechanical switch has a heat sensitive surface and is secured in a fluid-tight seal to the tub so that the heat sensitive surface is exposed to the interior of the tub to measure an internal temperature in the interior of the tub
Data Source
AI summary
A preferred embodiment of a fire containment system is implemented in a combination washer-dryer appliance equipped with air-vented exhaust. A fire suppression fluid conduit connected between a cold water valve outlet and a fire suppression fluid inlet positioned in a top portion of a tub of the appliance provides a path of cold water flow into an interior space of the tub. A valve control signal applied to a valve actuator associated with the cold water valve outlet actuates it upon a presumed occurrence of presence of fire in the interior space, as indicated by an electromechanical switch set in the top portion of the tub to measure an internal temperature of the interior space. The valve control signal thereby causes cold water flow through the fire suppression fluid conduit and into the interior space of the tub to contain and extinguish a fire burning within it.