Improving Cryogenic Temperature Monitoring with Fiber Optic Sensors
Across various industrial, scientific, and medical applications, the process of controlling temperatures and processing liquefied gases in cryogenic processes is key.
From separating atmospheric air into its elemental components to facilitating the storage and transportation of liquefied gases like liquid natural gas (LNG) and liquid hydrogen (LH2), maintaining precise temperature conditions is critical for efficiency, safety, and performance in these industries.
In these processes, there is a need for close control of the temperature of the fluids for a multitude of reasons:?
Limitations of Current Temperature Sensors
However, traditional electrical or electronic sensors face limitations in meeting the stringent requirements of cryogenic applications.?
Conventional electronic temperature sensors may have limited cryogenic sensitivity, an inability for multiple measurement points without cumbersome cabling, susceptibility to magnetic and electromagnetic interference (EMI), and safety concerns when handling explosive fluids; all these factors can make them unsuitable for use in certain cryogenic processes.?
Fibre Optic temperature sensors utilising fibre Bragg grating (FBG) technology emerge as a promising solution, as they are able to address many of these challenges. FBG sensors offer advantages such as EMI immunity, dense multiplexing capabilities, and intrinsic safety, making them well-suited for demanding environments.
However, until recently, FBG sensors have exhibited limited sensitivity at ultra-low temperatures, negating their benefits in cryogenic applications. Proximion, a leader in fibre optic sensing solutions, recognized this limitation and looked to develop a variant of FBG temperature sensors with enhanced sensitivity and performance for cryogenic processes.
The Power of WISTCryo Sensors
The breakthrough came in the form of the WISTCryo sensor array, which was engineered to deliver exceptional measurement accuracy and reliability even at temperatures as low as 20 K.?
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Unlike conventional FBG sensors, which rely on the thermo-optic effect for temperature measurement, the WISTCryo array leverages the stress-optic effect, where the thermal expansion of a material attached to or coating the fibre causes measurable changes in strain on the fibre.
With this, one of the key challenges in developing the WISTCryo sensor array was identifying materials with suitable coefficients of thermal expansion and mechanical properties for reliable performance at cryogenic temperatures. Through rigorous experimentation and innovation, Proximion engineers were able to successfully overcome these hurdles and craft a solution tailored for cryogenic applications.
Benefits of WISTCryo Sensor
1. High Accuracy and Stability: With a unique grating writing process and probe mechanical design, the WISTCryo sensor array ensures high sensitivity and stability down to 20K, enabling precise temperature monitoring in cryogenic environments.
2. High Spatial Resolution: Each sensor can accommodate numerous FBGs, allowing for dense multiplexing and customizable FBG spacing without the need for splices between the FBGs. This design flexibility enables precise temperature mapping in complex cryogenic systems.
3. EMI Immunity: WISTCryo sensors are impervious to magnetic and electromagnetic interference, making them ideal for use in environments where EMI is a concern, such as certain cryogenic processes.
4. Intrinsically Safe: Operating without electrical power, WISTCryo sensors are part of inherently safe systems when paired with Proximion's ATEX-certified interrogator, ensuring peace of mind in hazardous environments.
5. Small Form Factor: Despite offering multiple temperature measurements in a single probe, WISTCryo sensors maintain a low-profile design probe, enabling installation in previously inaccessible locations within cryogenic systems.
The introduction of the WISTCryo sensor array marks a significant advancement in cryogenic temperature monitoring technology. By overcoming the limitations of traditional sensors and even FBG sensors in this aspect, Proximion has opened new avenues for enhancing efficiency, safety, and control in cryogenic processes across various industries.
For further details about the WISTCryo development, please refer to our application note.
To learn more about the use of WISTCryo sensors in cryogenic temperature sensing, contact us today!?