Ammonia Sensor with Acid-Functional Sorbent and Thermal Indicator
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Solution Overview
Problem
Current ammonia sensors have limitations in detecting a wide range of concentrations, are often power-intensive, and are not compact enough for efficient use in identifying source points of ammonia leaks in industrial settings, particularly in refrigeration systems, where ammonia is hazardous and requires precise monitoring to prevent explosions and ensure worker safety.
Innovation Solution
The development of an ammonia sensor comprising a thermal indicator component, such as an electronic thermal sensor, irreversible temperature indicator, or heat-shrinkable film, in thermal contact with an acid-functional porous sorbent that generates thermal energy upon ammonia exposure, allowing for detectable responses indicating ammonia presence through dimensional changes, electronic signals, or colorimetric changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrochemical or polymer thin film capacitive sensors are used for ammonia detection, then sensitivity is improved, but upper detection limit is restricted to around 20,000-30,000 ppm
Solution Approach 1:
The patent changes the detection mechanism from electrochemical/polymer-based to thermal-based, utilizing the exothermic reaction between ammonia and acid-functional porous sorbent. This parameter change enables detection across a broader concentration range (from low ppm to high percentage levels) while maintaining sensitivity through the thermal indicator component.
2Measurement precision
If IR sensors or other electronic sensors are used, then detection capability is improved, but device size and power consumption increase
Solution Approach 1:
The sensor utilizes the exothermic reaction between ammonia and the acid-functional porous sorbent to generate its own thermal signal. The chemical reaction itself provides the energy needed for detection, eliminating the need for external power sources or complex electronic components, thereby achieving self-powered operation.
Solution Approach 2:
The patent replaces electronic/digital sensing systems with a chemical-thermal system. The detection is achieved through the exothermic chemical reaction and subsequent thermal indication, substituting complex electronic infrastructure with a simpler chemical-based mechanism that requires no external power.
3Area of stationary object
If area sensors are deployed for ammonia monitoring, then coverage is improved, but ability to locate source points quickly deteriorates
Solution Approach 1:
The patent creates sensors with localized high sensitivity to ammonia through the acid-functional porous sorbent material. The sorbent concentrates and reacts with ammonia at the local sensor site, providing strong thermal signals even at low concentrations, enabling rapid source location when multiple sensors are deployed across an area.
4Ease of operation
If handheld devices are used for worker safety monitoring, then portability is improved, but operational efficiency and continuous monitoring capability deteriorate
Solution Approach 1:
The sensor design uses inexpensive acid-functional porous sorbent material that can be replaced or regenerated. The simple thermal indicator components are also cost-effective, allowing for disposable or easily replaceable sensor units that maintain high portability while enabling continuous monitoring through frequent deployment and replacement.
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 solution enables effective detection of ammonia across a broad concentration range, improving the ability to locate source points of leaks and enhancing safety by providing a compact, power-efficient sensor that can monitor ammonia levels accurately, reducing the risk of explosions and ensuring worker safety in hazardous environments.
Implementation Method 1
This sensor utilizes an exothermic interaction between ammonia and the acid in contact with the (high surface area) porous sorbent. The heat generated from the interaction, which is typically reactive (as opposed to catalytic), causes a detectable response from the thermal indicator component(s)
Implementation Method 2
an acid-functional porous sorbent in thermal contact with the at least one thermal indicator component
Data Source
AI summary
The present disclosure provides an ammonia sensor and method of use. The sensor includes: at least one thermal indicator component independently selected from an electronic thermal sensor, an irreversible temperature indicator, and a heat-shrinkable film; an acid-functional porous sorbent in thermal contact with the at least one thermal indicator component; and an acid having a boiling point above 120° C. and a pKa of no greater than 2.5. The acid is impregnated in or covalently attached to the porous sorbent. The method includes: placing an ammonia sensor in contact with a container holding a volume of ammonia; and monitoring the ammonia sensor for a detectable response from the at least one thermal indicator component due to contact of ammonia with the acid that generates thermal energy sufficient to cause the response.