Fire protection device
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Solution Overview
Problem
In heat pumps using flammable natural working fluids, existing safety measures face challenges in detecting and mitigating critical concentrations of escaped gases, particularly propane, due to the difficulty in designing explosion-proof sensors and the risk of ignition in hermetically sealed spaces, especially during rare situations like icing, power failures, or extended downtime.
Innovation Solution
A device for an externally installed heat pump with a housing containing a container of fire extinguishing powder under pressure, a gas detector, a switchable shut-off valve, and a dispersing device that releases the powder as a fine mist when the gas concentration reaches above 40% of the ignitability limit, preventing ignition by dispersing the powder through the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical sensors are used to detect critical concentrations of flammable working fluid, then detection capability is improved, but explosion risk increases
Solution Approach 1:
The patent replaces electrical sensors with infrared sensors for detecting flammable gas concentrations. Infrared sensors use optical detection instead of electrical components, eliminating the explosion risk associated with electrical sparks while maintaining detection capability. This substitution resolves the contradiction by removing the harmful electrical element while preserving the measurement function.
Solution Approach 2:
The patent introduces inert gas (nitrogen or carbon dioxide) into the housing when flammable gas concentration reaches a critical level, creating an inert atmosphere that prevents ignition. This approach allows continuous monitoring and response without requiring electrical sensors to be present in the potentially explosive environment, as the inerting system activates preventively before ignition can occur.
2Reliability
If the housing is hermetically sealed to contain leaks, then containment is improved, but detection and response time deteriorates
Solution Approach 1:
The patent segments the containment space into the hermetically sealed housing and the surrounding environment, with a controlled interface. The housing maintains hermetic sealing for reliability, while the interface includes ventilation openings and sensor positions that allow detection of leaks without compromising the seal. This segmentation enables both containment and timely detection.
Solution Approach 2:
The patent introduces an intermediary detection system (infrared sensors positioned at strategic locations) that can detect flammable gas concentrations through the hermetic seal or at ventilation interfaces without requiring the seal to be breached. This intermediary detection mechanism maintains containment integrity while enabling timely leak detection and response.
3Reliability
If fire extinguishing powder is released at low concentrations to prevent ignition, then safety is improved, but powder consumption increases
Solution Approach 1:
The patent implements preliminary action by introducing inert gas or fire extinguishing powder when the flammable gas concentration reaches a predetermined threshold level (before reaching the lower flammability limit). This preventive measure stops the concentration from rising to dangerous levels, ensuring safety while minimizing powder consumption by acting only when necessary rather than continuously.
Solution Approach 2:
The patent uses parameter changes by monitoring and responding to specific concentration thresholds of the flammable working fluid. The system activates safety measures at predetermined concentration levels (e.g., 25% of the lower flammability limit), optimizing the balance between safety and resource consumption by acting only when parameters indicate potential danger.
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 prevents the ignitability of the working fluid-air mixture by releasing fire extinguishing powder at strategic concentrations, ensuring safety by avoiding explosive situations and protecting against fires through controlled dispersion of inerting agents.
Implementation Method 1
a gas detector with a measurement of the content of gaseous working fluid
Implementation Method 2
the fire extinguishing powder is finely atomized or sprayed under pressure upon triggering
Implementation Method 3
Other chemicals that neutralize free radicals, such as those formed during combustion, can also be used. By binding these free radicals beforehand, ignition is reliably prevented.
Data Source
Figure 1
AI summary
Device for an externally installed heat pump (1) comprising a refrigeration circuit with a flammable working fluid, comprising a housing (2) with at least one opening (7), at least one container (3) containing fire extinguishing powder under pressure, a gas detector (4) with a measurement of the content of gaseous working fluid, a switchable shut-off valve (5) which is connected to the container (3) under pressure, and an outlet line into the housing (1) which is connected to the shut-off valve (5).