Abstract
Response time is the key index of on-line monitoring system. To improve the response speed of traditional bead thermal conductivity CO2 sensor, this paper proposes to use multi-walled carbon nanotubes (MWCNTs) to improve the performance of gas sensor carrier. Nano-sized γ-Al2O3/CeO2 powder was synthesized by chemical precipitation method under the action of ultrasonic wave. SEM morphology reveals a particle size of 20–50 nm. MWCNTs were hydroxylated and the solution was then prepared by adding a certain amount of dispersant under ultrasonic wave. The composite support of γ- Al2O3/CeO2/MWCNTs was prepared by wet mixing carbon nanotube solution into the above support materials. Using dynamic resistance matching and black component technology, the influence of radiation heat and environmental temperature and humidity is reduced. Results show that the designed thermal conductivity sensor has consistent response and recovery time to different concentrations of CO2, with a T90 response time of 9 s and a T90 recovery time of 13 s, which is faster compared to major commercial Carbon dioxide sensors. The average sensitivity of the sensor is 0.0075 V/10% CO2. Therefore, the high thermal conductivity and pore characteristics of carbon nanotubes can effectively improve the response speed of the thermal conductivity sensor.
Highlights
A large number of greenhouse gas CO2 emissions aggravate the global warming
Bin Shen (Shen et al, 2018) and others studied the pore forming technology of multi-walled carbon nanotubes (MWCNTs) supported on aligned nanotubes and designed and fabricated a kind of hot-wire-coated ceramic powder thermal conductivity sensor for methane detection with a response recovery time of 8 s and 16 s (Xibo et al, 2013)
A thermal conductivity gas sensor consists of a detecting element and a compensating element, which are a pair of working components (Figure 1A) consisting of a platinum hot-wire resistor and carrier (Figure 1B)
Summary
A large number of greenhouse gas CO2 emissions aggravate the global warming. Acid rain, haze, and other bad weather caused huge economic losses and serious environmental damage (Hansen and Sato, 2004). Bin Shen (Shen et al, 2018) and others studied the pore forming technology of MWCNTs supported on aligned nanotubes and designed and fabricated a kind of hot-wire-coated ceramic powder thermal conductivity sensor for methane detection with a response recovery time of 8 s and 16 s (Xibo et al, 2013). A thermal conductivity gas sensor consists of a detecting element and a compensating element, which are a pair of working components (Figure 1A) consisting of a platinum hot-wire resistor and carrier (Figure 1B). These two components are separately assembled into two standard tubes. R3 is a sliding rheostat used to adjust the sensor’s zero output value, which is 2000
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