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The schematic of the experimental apparatus for simulating the TAD process.
The schematic of the experimental apparatus for simulating the TAD process.
An experimental apparatus was designed and built to simulate the through air drying process under various drying conditions. An air pressure regulator, connected to a compressed air line, filters and reduces the pressure to 400 𝑘𝑃𝑎 to feed the mass flow controller unit (MFC) safely.
The MFC unit provides an adjustable flowrate of 𝑚̇ ≤ 3.2 𝑘𝑔/𝑚2𝑠 through the paper sample of 35 𝑚𝑚 by 35 𝑚𝑚 using a built-in closed loop control system.
The air supply has a temperature and absolute humidity of 𝑇 = 20 ± 0.6℃ and 𝜔 = 1.43 ± 0.51 𝑔/𝑘𝑔 (𝑅𝐻 ≅ 10%), respectively. A pair of pressure transducers are utilized to measure the static pressure of the air at the MFC outlet and directly ahead of the paper sample.
Data from the feedback generated by the MFC, thermocouples and pressure transducers are collected using a data acquisition system (DAQ).
The final experimental apparatus. (The electronics and DAQ are not shown in the image.)
The final experimental apparatus. (The electronics and DAQ are not shown in the image.)
Example of the result of drying tests for different fabrics at different temperatures and flowrates. High drying intensity ⇒ correlation between the drying time and fabric structural properties.
Example of the result of drying tests for different fabrics at different temperatures and flowrates. High drying intensity ⇒ correlation between the drying time and fabric structural properties.
Contours of moisture content in a paper sample at different times (𝑡) during the drying. 𝑇=20℃, 𝑚 ̇=1.6 𝑘𝑔/𝑚2 𝑠, Fabric: FT3, and FoV: 30 𝑚𝑚 by 30 𝑚𝑚.
Contours of moisture content in a paper sample at different times (𝑡) during the drying. 𝑇=20℃, 𝑚 ̇=1.6 𝑘𝑔/𝑚2 𝑠, Fabric: FT3, and FoV: 30 𝑚𝑚 by 30 𝑚𝑚.
- For all fabrics, the pattern of drying is superficially random.
- The first and second cycle of TAD for a paper sample shows strong correlation (𝑅 ̅=0.75±0.15).
- There exist a weak correlation between the formation and the local permeability.
- A relatively constant, but weak, correlation, of 𝑅 ̅≈0.23 between the moisture content distribution and the formation is observed.
A hydrophobic paper sample I made for a test with TAD.
A hydrophobic paper sample I made for a test with TAD.
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