“…Silicate membrane Al-MCM-48 was studied on H 2 O/O 2 separation process to compare with MCM-48. 25 The α-Al membrane was used as support with pore diameter of 0.2 µm and thickness of 2 mm. The thickness of skin layer was 25 µm and 45 µm for MCM-48 and Al-MCM-48, respectively, as shown in Figure 1.…”
Section: Methodsmentioning
confidence: 99%
“…Figure 1.SEM micrograph of (a) MCM-48 membrane and (b) Al-MCM-48 membrane. 25 SEM: scanning electron microscope.…”
Section: Methodsmentioning
confidence: 99%
“…Seshadri and Lin 25 identified transfer mechanism of gas in membrane as activated diffusion, Knudsen diffusion and viscous flow, dominating in microporous (d p < 2 nm), mesoporous (2 nm < d p < 50 nm) and macroporous (d p > 50 nm) membrane, successively. Theoretically, the best separation factor can be gained when Knudsen diffusion is the governing mechanism as represented by equation (5).…”
Air dehumidification plays an important role in improving air quality and maintaining thermal comfort. Increasing attention is paid to the membrane-based technology, which is based on water vapour transmembrane transport driven by mass transfer potential, together with sensible heat transfer under temperature difference. Membrane-based air dehumidification has been applied in heating, ventilation and air conditioning, compressed air dehumidification and environmental control in space vehicle, and some other engineering fields. This paper summarizes recent research results in these fields, including fundamental principles, membrane materials, membrane module structures, operation conditions and theory models. In the end, two methods of membrane-based dehumidification performance evaluation are introduced from perspective of energy and exergy, respectively.
“…Silicate membrane Al-MCM-48 was studied on H 2 O/O 2 separation process to compare with MCM-48. 25 The α-Al membrane was used as support with pore diameter of 0.2 µm and thickness of 2 mm. The thickness of skin layer was 25 µm and 45 µm for MCM-48 and Al-MCM-48, respectively, as shown in Figure 1.…”
Section: Methodsmentioning
confidence: 99%
“…Figure 1.SEM micrograph of (a) MCM-48 membrane and (b) Al-MCM-48 membrane. 25 SEM: scanning electron microscope.…”
Section: Methodsmentioning
confidence: 99%
“…Seshadri and Lin 25 identified transfer mechanism of gas in membrane as activated diffusion, Knudsen diffusion and viscous flow, dominating in microporous (d p < 2 nm), mesoporous (2 nm < d p < 50 nm) and macroporous (d p > 50 nm) membrane, successively. Theoretically, the best separation factor can be gained when Knudsen diffusion is the governing mechanism as represented by equation (5).…”
Air dehumidification plays an important role in improving air quality and maintaining thermal comfort. Increasing attention is paid to the membrane-based technology, which is based on water vapour transmembrane transport driven by mass transfer potential, together with sensible heat transfer under temperature difference. Membrane-based air dehumidification has been applied in heating, ventilation and air conditioning, compressed air dehumidification and environmental control in space vehicle, and some other engineering fields. This paper summarizes recent research results in these fields, including fundamental principles, membrane materials, membrane module structures, operation conditions and theory models. In the end, two methods of membrane-based dehumidification performance evaluation are introduced from perspective of energy and exergy, respectively.
“…The key diffusion mechanism of water vapour in membrane pores varies depending on the pore size. 32 If the pores should be large enough relative to the mean free path length of water vapour molecules ( Kn < 0.01), the water vapour would transport by Poiseuille flow, also known as viscous flow. However, if the pores are much smaller than the mean free path length ( Kn > 10), Knudsen diffusion would dominate and the permeability would be independent of the total pressure difference.…”
A novel hydrophobic membrane-based dehumidification technology with chilled water is proposed to substitute the traditional dew point method for humidity control in spacecraft, which fulfils the tough tasks of air/water separation and water reuse under low gravity at the same time. A prototype hydrophobic membrane module was designed and fabricated by packing 853 hollow fibres in the shell-andtube configuration, which could prevent the leakage of the tube-side chilled water to the air side. Theoretical models concerning conjugated heat and mass transfer have been established for the explanation and prediction of the moisture migration across the membranes. Experiments were conducted to validate the theoretical models and the feasibility of water vapour removal under various operating conditions. Although undesirable dewing occurred on the outer membrane surface due to the slow mass transfer relative to heat transfer across the membranes, it was verified by the water increase in graduated cylinder that some water vapour actually transferred through the membrane pores under partial pressure difference. A maximum net dehumidification rate (excluding dewing) of 45 g/h has been achieved by the experiment.
“…However, the synthesis of inherently hydrothermal stable mesoporous membrane was scarcely probed [24]. On the other hand, compared to the hotly used or studied MCM-41 and MCM-48 membranes [24][25][26][27][28][29][30], mesoporous Ti-containing zeolite membrane has been received less attention despite the fact that Ti-MCM-41 was reported early in 1994 and has been extensively studied [5][6][7]31]. In addition to the separation, Ti-containing mesoporous membrane would find their niche in composite membrane reactors, catalytic membrane reactors and microreactors just like the microporous zeolite membranes with full application opportunities in the mentioned areas [32][33][34][35][36][37][38][39].…”
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