scholarly journals Polydimethyl siloxane/MIL-101 Composites for Enhanced Toluene Adsorption in the Presence of Humidity

2021 ◽  
Author(s):  
Luqman Hakim Mohd Azmi ◽  
Pavani Cherukupally ◽  
Elwin Hunter-Sellars ◽  
Bradley P. Ladewig ◽  
Daryl R. Williams
Keyword(s):  
Vapor Phase ◽  
Co Adsorption ◽  
Deposition Process ◽  
Polydimethyl Siloxane ◽  
Hydrophobicity Index ◽  
Molecular Weights ◽  
Adsorbent Regeneration ◽  
Adsorption Of Water ◽  
And Performance ◽  
The Stability

<div><b>ABSTRACT</b> <br></div><div><br></div><div> Competition between atmospheric moisture and volatile organic compounds (VOCs) for an adsorbent’s sites can significantly impact its VOC removal efficiency. The development of moisture-tolerant adsorbents is essential to address this issue. A vapor phase deposition process using polydimethylsiloxane (PDMS) has created a hydrophobic form of the highly porous, normally hydrophilic, MOF MIL-101. After optimizing the PDMS vapor deposition time and molecular weights, hydrophobicity index calculations verified the improved hydrophobicity of the coated MOF (MIL-PDMS-Sigma-0.25) over its pristine form. The surface area, pore volume as well as single component vapor adsorption of water and toluene capacities were also preserved, resulting to similar performance to MIL-101. Toluene-water vapor co-adsorption experiments were conducted at 40% RH using two toluene concentrations: 0.5% P/P<sub>0</sub> and 10% P/P<sub>0</sub>, mimicking environmental VOC and industrial concentrations, respectively. At 0.5% P/P<sub>0</sub>, MIL-PDMS-Sigma-0.25 exhibited 60% higher adsorption capacity and twice the rate of toluene capture relative to pristine MIL-101, as well as a 3-fold higher toluene uptake relative to a commercial activated carbon. Preliminary adsorbent regeneration experiments confirm the stability and performance of MIL-PDMS-Sigma-0.25. Using a simple vapor phase modification, this new MOF-composite material offers superior competitive toluene vapor uptake in humidified real-world conditions at VOC concentrations. </div>

scholarly journals Polydimethyl siloxane/MIL-101 Composites for Enhanced Toluene Adsorption in the Presence of Humidity

2021 ◽  
Author(s):  
Luqman Hakim Mohd Azmi ◽  
Pavani Cherukupally ◽  
Elwin Hunter-Sellars ◽  
Bradley P. Ladewig ◽  
Daryl R. Williams
Keyword(s):  
Vapor Phase ◽  
Co Adsorption ◽  
Deposition Process ◽  
Polydimethyl Siloxane ◽  
Hydrophobicity Index ◽  
Molecular Weights ◽  
Adsorbent Regeneration ◽  
Adsorption Of Water ◽  
And Performance ◽  
The Stability

<div><b>ABSTRACT</b> <br></div><div><br></div><div> Competition between atmospheric moisture and volatile organic compounds (VOCs) for an adsorbent’s sites can significantly impact its VOC removal efficiency. The development of moisture-tolerant adsorbents is essential to address this issue. A vapor phase deposition process using polydimethylsiloxane (PDMS) has created a hydrophobic form of the highly porous, normally hydrophilic, MOF MIL-101. After optimizing the PDMS vapor deposition time and molecular weights, hydrophobicity index calculations verified the improved hydrophobicity of the coated MOF (MIL-PDMS-Sigma-0.25) over its pristine form. The surface area, pore volume as well as single component vapor adsorption of water and toluene capacities were also preserved, resulting to similar performance to MIL-101. Toluene-water vapor co-adsorption experiments were conducted at 40% RH using two toluene concentrations: 0.5% P/P<sub>0</sub> and 10% P/P<sub>0</sub>, mimicking environmental VOC and industrial concentrations, respectively. At 0.5% P/P<sub>0</sub>, MIL-PDMS-Sigma-0.25 exhibited 60% higher adsorption capacity and twice the rate of toluene capture relative to pristine MIL-101, as well as a 3-fold higher toluene uptake relative to a commercial activated carbon. Preliminary adsorbent regeneration experiments confirm the stability and performance of MIL-PDMS-Sigma-0.25. Using a simple vapor phase modification, this new MOF-composite material offers superior competitive toluene vapor uptake in humidified real-world conditions at VOC concentrations. </div>

scholarly journals Analytical Modeling and Design of Novel Conical Halbach Permanent Magnet Couplings for Underwater Propulsion

2021 ◽  
Vol 9 (3) ◽  
pp. 290
Author(s):  
Yukai Li ◽  
Yuli Hu ◽  
Youguang Guo ◽  
Baowei Song ◽  
Zhaoyong Mao
Keyword(s):  
Permanent Magnet ◽  
Analytical Calculation ◽  
Underwater Propulsion ◽  
Conical Structure ◽  
Torque Analysis ◽  
Dynamic Seal ◽  
And Performance ◽  
The Stability ◽  
Propulsion Unit ◽  
Force Calculation

Permanent magnet couplings can convert a dynamic seal into a static seal, thereby greatly improving the stability of the underwater propulsion unit. In order to make full use of the tail space and improve the transmitted torque capability, a conical Halbach permanent magnet coupling (C-HPMC) is proposed in this paper. The C-HPMC combines multiple cylindrical HPMCs with different sizes into an approximately conical structure. Compared with the conical permanent magnet couplings in our previous work, the novel C-HPMC has better torque performance and is easy to process. The analytical calculation method of transmitted torque of C-HPMC is proposed on the basis of torque calculation of the three common types of HPMCs. The accuracy of the torque calculation of the three HPMCs is verified, and the torque performance of the three HPMCSs of different sizes is compared and discussed. The “optimal type selection” method is proposed and applied in the design of C-HPMC. Finally, on the basis of torque analysis calculation and axial force calculation, a complete flowchart of the design and performance analysis of C-HPMC is described.

Adaptive attitude-tracking control of spacecraft considering on-orbit refuelling

2020 ◽  
pp. 014233122097313
Author(s):  
Yiqi Xu
Keyword(s):  
Tracking Control ◽  
Closed Loop ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Inertia Model ◽  
And Performance ◽  
Attitude Tracking Control ◽  
The Stability

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.

Nondestructive Test on Typical Roadway Supports of a Mine via Drilling Core and Ground Penetrating Radar

2011 ◽  
Vol 368-373 ◽  
pp. 2411-2416
Author(s):  
Jian Ping Han ◽  
Hai Peng Liu
Keyword(s):  
Ground Penetrating Radar ◽  
Geological Structure ◽  
Surrounding Rock ◽  
Potential Threat ◽  
Real Performance ◽  
Design Requirements ◽  
And Performance ◽  
The Stability ◽  
Ground Penetrating ◽  
Drilling Core

Temporary or permanent supports are necessary in underground construction for maintaining the stability and limiting the damage of surrounding rock. Due to the uncertainty of geological structure, the specificity of the underground environment as well as other factors, the quality and performance of supporting structure are often difficult to satisfy the design requirements, which not only seriously affects the normal construction and operation of mines but also has the potential threat to the safety of underground production. In order to investigate the influence of the unfavorable geologic environment on supporting concrete and evaluate the real performance of roadway supports of a mine, 17 typical projects were chosen and the strength of supporting concrete was detected by nondestructive drilling core method. The result shows that the strength is widely less than the design value. Furthermore, 4 projects of them were investigated by the ground penetrating radar (GPR) in order to evaluate the feasibility of GPR in the performance investigation of the roadway supports of a mine. The results indicate that ground penetrating radar is capable of measuring the thickness of the support, the distribution of rebars and the defects of the surrounding rock.

Map Width Enhancement Technique for a Turbocharger Compressor

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early
Keyword(s):  
Performance Improvement ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Comparison Study ◽  
Heavy Duty ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
And Performance ◽  
The Stability ◽  
The Impact

This paper presents an investigation of map width enhancement and the performance improvement of a turbocharger compressor using a series of static vanes in the annular cavity of a classical bleed slot system. The investigation has been carried out using both experimental and numerical analysis. The compressor stage used for this study is from a turbocharger unit used in heavy duty diesel engines of approximately 300 kW. Two types of vanes were designed and added to the annular cavity of the baseline classical bleed slot system. The purpose of the annular cavity vane technique is to remove some of the swirl that can be carried through the bleed slot system, which would influence the pressure ratio. In addition to this, the series of cavity vanes provides a better guidance to the slot recirculating flow before it mixes with the impeller main inlet flow. Better guidance of the flow improves the mixing at the inducer inlet in the circumferential direction. As a consequence, the stability of the compressor is improved at lower flow rates and a wider map can be achieved. The impact of two cavity vane designs on the map width and performance of the compressor was highlighted through a detailed analysis of the impeller flow field. The numerical and experimental study revealed that an effective vane design can improve the map width and pressure ratio characteristic without an efficiency penalty compared to the classical bleed slot system without vanes. The comparison study between the cavity vane and noncavity vane configurations presented in this paper showed that the map width was improved by 14.3% due to a significant reduction in surge flow and the peak pressure ratio was improved by 2.25% with the addition of a series of cavity vanes in the annular cavity of the bleed slot system.

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