Hydrogen sensor is a gas detector that detects the presence of hydrogen. They contain micro hydrogen point contact sensors and are used to locate hydrogen leaks. They are considered low cost, compact, durable, and easy to maintain compared to conventional gas detecting instruments.
Video Hydrogen sensor
Known issues
There are five major problems with hydrogen detectors:
- Reliability: Functionality should be easily verified.
- Performance: 0% hydrogen detection in air or better
- Response time & lt; 1 second.
- Lifetime: At least time between scheduled maintenance.
- Cost: Goal is $ 5 per sensor and $ 30 per controller.
Additional requirements
- Scope of measurement range from 0.1-10.0% concentration
- Operating in temperature -30Ã, Â ° C to 80Ã, Â ° C
- Accuracy in 5% of full scale
- Works in an ambient air gas environment in the relative 10-98% relative range
- Resistance to hydrocarbons and other disorders.
- Lifetime more than 10 years
Maps Hydrogen sensor
Micropensor type
There are different types of hydrogen microponors, which use different mechanisms to detect gas. Palladium is used in many of these, as it selectively absorbs hydrogen gas and forms palladium hydride compounds. Palladium-based sensors have a strong temperature dependence that makes the response time too large at very low temperatures. Palladium sensors should be protected against carbon monoxide, sulfur dioxide and hydrogen sulfide.
Hydrogen fiber optic sensor
Several types of surface plasmon fiber resonance (SPR) sensors are used for the detection of hydrogen-point contacts:
- Bragg lattice fiber lined with palladium coating - Detects hydrogen with a metal barrier.
- Micromirror - With a thin layer of palladium on the split end, it detects changes to the backreflected light.
- Tapered fibers coated with palladium - Hydrogen alters the refractive index of palladium, and consequently the amount of loss in the waves evolves quickly.
Other types
- Low-electrochemical hydrogen sensor (ppm) hydrogen gas levels can be felt using electrochemical sensors consisting of arrays of electrodes packed so that they are surrounded by conductive electrolytes and the inflow of diffusely controlled capillary gases.
- MEMS hydrogen sensor - The combination of nanotechnology technology and microelectromechanical systems (MEMS) enables the production of well-functioning hydrogen microprocessors at room temperature. One type of MEMS-based hydrogen sensor is coated with a film consisting of nanostructured indium oxide (In 2 O 3 ) and lead oxide (SnO 2 ). A typical configuration for Pd based hydrogen sensors is the use of freestanding cantilever coated with Pd. In the presence of H 2 , the Pd layer expands and thus induces stress that causes the cantilever to bend. Pd-coated nanomechanical resonators have also been reported in the literature, depending on the mechanical resonance frequency shift caused by stress caused by the presence of H 2 gas. In this case, the response rate is increased through the use of a very thin Pd coating (20 nm). Moderate heating is presented as a solution to the observed response disorder in humid conditions.
- Thin film sensors - Thin-film palladium sensors are based on opposite properties that depend on nanoscale structures in thin films. In thin films, nanosized palladium particles swell when hydrides are formed, and in the process of expansion, some of them form new electrical connections with their neighbors. Resistance decreases due to the increasing number of conduction paths.
- Thick film sensors - devices typically have two main components: 1) a thick layer (hundreds of microns) of some semiconductor material (SnO 2 , In 2 O 3 ), is called "matrix" and the catalytically active additive top layer such as precious metal (Pd, Pt) and metal oxide (Co x y ) accelerates the hydrogen oxidation reaction on the surface, which makes the sensor response much faster. The role of "matrix" is to transduct signals to a measurement system. Thick film sensors are more stable than thin film sensors in terms of drifting signals, but generally show a slower sensor response due to diffusion constraints into thick layers. The thick film sensor technology is increasingly being replaced by thin film approaches due to the increasing need for sensor integration into modern electronic systems. Thick film sensors require an increase in temperature for their operation and therefore seem to be less compatible with digital electronic systems.
- Chemochromic hydrogen sensor - Reversible and irreversible chemokromic hydrogen sensor including smart pigment paint that visually identifies leakage of hydrogen by discoloration. This sensor is also available as a tape. Another method has been developed to test the production of biological hydrogen.
- Schottky-based diode sensor - A Schottky-based hydrogen gas sensor using palladium alloy gates. Hydrogen can be absorbed selectively at the gate, lowering Schottky's energy barrier. The Schottky Pd/InGaP metal-semiconductor (MS) diagram can detect concentrations of 15 parts per million (ppm) of H 2 in the air. Semiconductors of silicon carbide or silicon substrates are used.
- Electrically conductive La-Mg2-Ni, absorbing hydrogen near ambient conditions, forms a nonmetallic LaMg2NiH7 hydride as an insulator.
The sensors are usually calibrated at the manufacturing plant and are applicable for the lifetime of the unit.
Upgrade
Siloxane increases the sensitivity and reaction time of the hydrogen sensor. Detection of hydrogen levels as low as 25 ppm can be achieved; well below the lower hydrogen explosive limit of about 40,000 ppm.
See also
- Hydrogen analyzer
- Hydrogen leak test
- Hydrogen safety
- Catharometer
- Sensor list
- Optical fiber
- Nanoorod zinc oxide sensor
References
External links
- Hydrogen sensing and detection
- ISO TC 197 WG13
- Nanoparticles-Integrated Microsensor
- Fiber grid for hydrogen sensing
- Wide-Hydrogen Sensor
- Bragg type fiber optic sensor
- EU sensor sheet
- EERE H2scan success story
- Type-NCKU-Semiconductor hydrogen sensor 2010 -
- Argonne National Laboratory (Thin Film)
- Roads2HyCom
Source of the article : Wikipedia
0 Comments