This work was supported by the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization (grant number U1609205) and National Natural Science Foundation of China (grant number 51605443), the Key Research and Development Project of Zhejiang Province (grant number 2018C01027), the 521 Talent Project of Zhejiang Sci-Tech University, and the Young Researchers Foundation of Zhejiang Provincial Top Key Academic Discipline of Mechanical Engineering of Zhejiang Sci-tech University (grant number ZSTUME02B13).

1. Experimental rig set-up
NOTE: See Figure 1.
<ol>
	<li>Hot air blower unit
	<ol>
		<li>Ensure that the hot air blower is connected to the air nozzle through a high temperature resistant silicone pipeline that is heat-insulated with asbestos material. Gradually adjust the air nozzle to the desirable incline angle to control the air flow direction. For this work, the incline angle, &#945;, varied between 60&#176; and 90&#176;.</li>
		<li>Switch on the air blower fan and the resistance wire. 
		NOTE: The order in which the fan and resistance wire are turned on cannot be reversed.</li>
		<li>Set the outlet temperature of the hot air blower by gradually adjusting the current through the resistance wire with the controller of the air blower, and measure the air flow temperature using the digital temperature sensor. For this work, the hot air temperature, T, varied between 70 &#176;C and 130 &#176;C.</li>
		<li>Measure the air flow velocity at the outlet of the air nozzle using the handheld multifunctional anemometer at room temperature (RT). For this work, the hot air velocity, Va, varied between 8-20 m/s. For accurate measurement of the air velocity, the probe should be perpendicular to the direction of the airflow.</li>
		<li>Gradually adjust the rotation speed of the air blower fan with the frequency converter to obtain the desired air flow velocity. Cover the air nozzle with a high thermal resistance board to disperse the heat flow to avoid thermal damage to people or devices.</li>
	</ol>
	</li>
	<li>Infrared thermograph unit
	<ol>
		<li>Fix the infrared thermograph onto the support frame directly above the air nozzle with about a 1 m distance. Connect the infrared thermograph with the computer using the net cable. Power on the infrared thermograph and open the operation software of the infrared thermograph on the computer. Select the connection mode as Ethernet so an IP address is assigned automatically to the infrared thermograph by the computer, and the object temperature can be read in real-time with the infrared thermograph.</li>
		<li>Fix a piece of standard fabric sample over the air nozzle with the needle plate fixture and adjust the distance between the air nozzle and sample to the desired value. In this work, 30 mm is used, which is 3x the diameter of the nozzle.</li>
		<li>Adjust the focus of the camera and set basic parameters via the computer. Open the &#34;parameters&#34; dialog box, set the temperature unit to &#176;C, set the thermal radiance to 0.95, set the ambient relative humidity to 50%, set the ambient temperature to 25 &#176;C, and set the distance between the measured object and camera to 1.5 m. This will ensure that the measured temperature is correct.</li>
		<li>As the tested fabric sample is prepared, fix it at the same location as the standard fabric sample, then record the temperature of the fabric with the computer as a video.</li>
	</ol>
	</li>
	<li>Uniform padder system
	<ol>
		<li>Make sure the uniform padder is connected to the air compressor through the pipeline. Power on the air compressor and set its maximum output pressure to 0.8 MPa.</li>
		<li>Manually adjust the pressure regulators to control the air pressure to the couple of the clamp cylinders, which are connected to the upper roller of the padder, so that residual moisture in the fabric can be controlled. Ensure that the pressure on both sides of the roller are equal so that the moisture content of the fabric distributed over each area is even.</li>
		<li>Power on the padder, make sure the roller can rotation freely, then put the saturated fabric sample with sufficient moisture absorption onto the upper roller of the uniform padder, so that the tested fabric can be squeezed through the roller couple and moisture distribution inside the fabric can be controlled to be uniform.</li>
		<li>Power off the padder.</li>
	</ol>
	</li>
	<li>Weight and thickness measuring unit
	<ol>
		<li>Place an electronic scale on a horizontal platform and tare it. Place standard weights on the balance for calibration so that the specimen can be accurately weighted.</li>
		<li>Cut out a rectangular fabric sample with a width and length of 10 cm and 31 cm, respectively. Power on the thickness testing instrument (see Table of Materials) and connect it to the computer. Place these fabric samples on the test platform of the FTT. Open the operation software of the FTT, click &#34;start&#34; on the operation interface, then automatically test the thickness of the fabric by the FTT and record it on the operation interface.</li>
	</ol>
	</li>
	<li>Drying stove unit
	<ol>
		<li>Power on the drying stove and make sure no samples are in the drying room. Set the drying stove to a high temperature (120 &#176;C is used in this work) for 30 min to evaporate the moisture absorbed by the inner wall of the stove.</li>
		<li>Preheat the drying stove to the desired temperature (45 &#176;C is used in this work) so that the stove can be used directly for drying fabric samples.</li>
	</ol>
	</li>
</ol>
2. Testing specimen and the manufacturing process
<ol>
	<li>Cut out square fabrics of 250 mm x 250 mm from the same fabric used for the rectangular fabric sample with scissors and a triangle ruler for the manufacturing of test specimens (area of the fabric = 6.25 &#215; 104 mm2). Put the fabric specimens into the drying stove to evaporate the resident moisture absorbed from environment so that their net weight can be obtained.</li>
	<li>Take out one piece of fabric specimen from the drying stove, then measure the initial weight, W0, of the sample with the electronic balance.</li>
	<li>Immerse the fabric sample in water for 5 min to ensure that the fabric absorbs the moisture until saturation. Tile the saturated fabric sample onto the upper roller of the uniform padder to obtain the desired even initial moisture content.</li>
	<li>Power on the padder and set an initial pressure with the pressure regulators. As the tiled sample passes through the roller couple, power off the padder and remove the sample from the padder.</li>
	<li>Measure the weight of the wet fabric sample, W1, of the sample with the electronic balance. The residual moisture of the fabric can be calculated as C = (W1-W0)/W0, and the area average moisture content in the fabric can be calculated as Wa = (W1-W0)/A.</li>
	<li>If the desired moisture content, Cd, is not obtained, dry the rollers with a towel or paper towel first, and then repeat steps 2.4-2.5 until Cd is set.</li>
	<li>If necessary, cut out a sample strip from the same fabric used for preparing the testing specimen, then measure and record its thickness.</li>
</ol>
3. Data acquisition, post-processing, and analysis
<ol>
	<li>As done in step 1.1, set the outlet temperature and velocity of the air blower to the desired values and cover the nozzle with the high thermal resistance board. Once the tested fabric sample is prepared (section 2), fix it with the needle plate fixture for sequence testing and power on the infrared thermograph. Start to record the sample temperature.</li>
	<li>Remove the covered board that the hot air can impinge on the lower surface of tested sample directly. Observe changes in the drying temperature of the fabric on the computer during the drying process. When the drying temperature increases to a steady value and lasts for approximately 30 s, which means the sampled fabric is dry to the target status, stop recording. Take the sample away from the fixture and cover up the nozzle with the high thermal resistance board again.</li>
	<li>If necessary, set the target analysis area with a supporting post-processing tool for the infrared thermograph (for data plotting, saving, etc.) so that the drying features (normally how the temperature varies with time) of that point of the tested fabric can be obtained.</li>
	<li>If necessary, navigate the video to the portion of different drying stages and save the video frame as a colorful image. Then, the area of the region dried by hot air can be calculated by the image processing method according to the following steps14. First, gray the colorful image with the weighted average method to grayscale the image, then binarize the obtained grayscale image with the OSTU method by setting the threshold to the grayscale value in which the temperature in the image is close to the hot air temperature. Thus, the area of the dried region can be calculated on the binarization image.</li>
	<li>Repeat steps 3.1-3.4 and record the drying characteristics of each fabric sample by adjusting the air flow velocity, temperature, direction, as well as fabric material, physical parameters, etc.</li>
	<li>Observe all differences under varying air temperature, air velocity, airflow direction, and fabric thickness.</li>
</ol>

<ol>
	<li>Wang, G., Deng, Y., Xu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+air+jet+impingement+drying+of+okara+using+response+surface+methodology.">Optimization of air jet impingement drying of okara using response surface methodology.</a> Food Control. 59, 743-749 (2016).</li><li>Etemoglu, A. B., Ulcay, Y., Can, M., Avci, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mathematical+modelling+of+combined+diffusion+of+heat+and+mass+transfer+through+fabrics.">Mathematical modelling of combined diffusion of heat and mass transfer through fabrics.</a> Fibers and Polymers. 10 (2), 252-259 (2009).</li><li>Di, M. P., Frigo, S., Gabbrielli, R., Pecchia, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mathematical+modelling+and+energy+performance+assessment+of+air+impingement+drying+systems+for+the+production+of+tissue+paper.">Mathematical modelling and energy performance assessment of air impingement drying systems for the production of tissue paper.</a> Energy. 114 (2), 201-213 (2016).</li><li>Xiao, H. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drying+kinetics+and+quality+of+Monukka+seedless+grapes+dried+in+an+air-impingement+jet+dryer.">Drying kinetics and quality of Monukka seedless grapes dried in an air-impingement jet dryer.</a> Biosystems Engineering. 105 (2), 233-240 (2010).</li><li>Gu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+optimum+temperature+value+setting+for+the+heat-setting+process+based+on+PSO.">Study on optimum temperature value setting for the heat-setting process based on PSO.</a> 3rd International Conference on Advances in Energy, Environment and Chemical Engineering. 69, (2017).</li><li>Aihua, M., Yi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Numerical+heat+transfer+coupled+with+multidimensional+liquid+moisture+diffusion+in+porous+textiles+with+a+measurable-parameterized+model.">Numerical heat transfer coupled with multidimensional liquid moisture diffusion in porous textiles with a measurable-parameterized model.</a> Numerical Heat Transfer Part A - Applications. 56 (3), 246-268 (2009).</li><li>Angelova, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat+and+mass+transfer+through+outerwear+clothing+for+protection+from+cold:+influence+of+geometrical,+structural+and+mass+characteristics+of+the+textile+layers.">Heat and mass transfer through outerwear clothing for protection from cold: influence of geometrical, structural and mass characteristics of the textile layers.</a> Textile Research Journal. 87 (9), 1060-1070 (2017).</li><li>Wei, Y., Hua, J., Ding, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mathematical+model+for+simulating+heat+and+moisture+transfer+within+porous+cotton+fabric+drying+inside+the+domestic+air-vented+drum+dryer.">A mathematical model for simulating heat and moisture transfer within porous cotton fabric drying inside the domestic air-vented drum dryer.</a> The Journal of The Textile Institute. 108 (6), 1074-1084 (2016).</li><li>Cay, A., Gurlek, G., Oglakcioglu, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+and+modeling+of+drying+behavior+of+knitted+textile+materials.">Analysis and modeling of drying behavior of knitted textile materials.</a> Drying Technology. 35 (4), 509-521 (2017).</li><li>Neves, S. F., Campos, J. B. L. M., Mayor, T. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+determination+of+parameters+required+for+numerical+studies+of+heat+and+mass+transfer+through+textiles+-+Methodologies+and+experimental+procedures.">On the determination of parameters required for numerical studies of heat and mass transfer through textiles - Methodologies and experimental procedures.</a> International Journal of Heat and Mass Transfer. 81, 272-282 (2015).</li><li>Sousa, L. H. C. D., Motta Lima, O. C., Pereira, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+drying+kinetics+and+moisture+distribution+in+convective+textile+fabric+drying.">Analysis of drying kinetics and moisture distribution in convective textile fabric drying.</a> Drying Technology. 24 (4), 485-497 (2006).</li><li>Wang, X., Li, W., Xu, W., Wang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+on+the+Surface+Temperature+of+Fabric+in+the+Process+of+Dynamic+Moisture+Liberation.">Study on the Surface Temperature of Fabric in the Process of Dynamic Moisture Liberation.</a> Fibers and Polymers. 15 (11), 2437-2440 (2014).</li><li>Qian, M., Wang, J. H., Xiang, Z., Zhao, Z. W., Hu, X. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heat+and+moisture+transfer+performance+of+thin+cotton+fabric+under+impingement+drying.">Heat and moisture transfer performance of thin cotton fabric under impingement drying.</a> Textile Research Journal. , (2018).</li><li>Rafael, C. G., Richard, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Digital image processing. , (2007).</li></ol>

The authors have nothing to disclose.

This section provides a few tips necessary to ensure reliable quantitative results. First, the fabric specimens must be kept completely dry to ensure the initial weights are correct. This is achievable through the drying process (i.e., using a suitable drying stove). If possible, an environment humidity that is kept constant benefits the experiment.
Secondly, the fabric specimens must be well-processed to ensure that the moisture at each region of the fabric is uniform. This can be done by man...

Impinging drying is a very effective drying method due to its high heat, mass transfer coefficient, and short drying time. It has attracted extensive attention due to its numerous applications including chemical industry, food1, textile, dyeing2, paper making3,4, etc. Now, impinging drying is widely used for its enhanced transport characteristics, especially for the drying of textiles in the heat setting process5.
Fabric is impinging dried by the nozzle array for the heat setting. Nozzle layout affects the uniformity of drying temperature, which has a significant influence on the fabric properties, drying efficiency, and on the fabric surface directly. Thus, it is necessary to understand temperature distribution on the textile surface to design a better nozzle array. There has been little investigation in this field at the present, though there has been plenty of research on heat and moisture transfer performance of the fabric drying process so far. Some research has mainly focused on the natural evaporation of a textile under a specified heat source, in which the impinging drying process was not involved in these studies6,7. Some have focused on heat and moisture transfer of the textile with hot air drying, but the textile moisture and temperature were assumed to be uniform in these studies8,9,10,11. Furthermore, a few of these studies attempted to obtain the temperature distribution variation with time for studying the heat and moisture transfer of the textile under impinging drying.
Etemoglu et al.2 developed an experimental set-up for obtaining temperature variation with the time of the fabric and total drying time, but this set-up is limited to single-point temperature measurements. The initial moisture content distribution in the fabric is also neglected in this type of research. Wang et al.12 intended to obtain temperature distribution on the fabric by pasting thermocouples on the textile surface at various points, but surface temperature distribution was not able to be accurately obtained with their method. Obtaining temperature distribution at the air impingement area on a fabric with even humidity distribution is important for industrial printing and dyeing production, and it will provide better guidance on the distribution and arrangement strategy for object drying with a multi-nozzle13. The following procedure provides details to study the heat and moisture transfer of a fabric during the impinging drying process. The initial moisture content is well-controlled to be evenly distributed, while the surface temperature at every point of the fabric is obtained via the experimental set-up.
The experimental set-up consists of a hot air blower unit, infrared thermograph unit, uniform padder system, and other auxiliary devices. The hot air blower unit supplies the hot air with a specified temperature and velocity in an adjustable direction according to the experimental requirements. The infrared thermograph unit records the temperature history of each impinging drying process; thus, the temperature at each pixel point of the recorded video can be extracted with a supporting post-processing tool. The uniform padder system controls the even distribution of moisture content at every point of the fabric. Finally, the influence of air impingement parameters on fabric drying characteristic with fabric moisture uniform control method are investigated. The process can be carried out in a reproducible fashion following the standard protocol described below.

<table><tbody><tr><td>Air Blower</td><td>Zhejiang jiaxing hanglin electromechanical equipment co., Ltd.</td><td>HLJT-3380-TX10A-0.55</td><td>Air Volume: 900 m&lt;sup&gt;3&lt;/sup&gt;/s;</td></tr><tr><td>Anemometer</td><td>KIMO</td><td>MP210</td><td>Measurement range: 0-40 m/s; Accuracy: &amp;plusmn;0.1 m/s</td></tr><tr><td>Drying stove</td><td>Shanghai Shangyi Instrument Equipment Co., Ltd.</td><td>DHG 101-0A</td><td>precision: 1 &amp;deg;C; Temperature control range:10-300 &amp;deg;C</td></tr><tr><td>Electronic Balance</td><td>Hangzhou Wante Weighing Instrument Co., Ltd.</td><td>WT1002</td><td>Precision: 1 &amp;deg;C; Range: 100 g</td></tr><tr><td>Fabric Style Measuring Instrument</td><td>SDL Atlas</td><td>M293</td><td></td></tr><tr><td>Fabric Touch Tester</td><td>SDLATLAS Ltd</td><td></td><td>Fabric thickness tester</td></tr><tr><td>High thermal resistance board</td><td>Baiqiang</td><td></td><td>Flame resistance, Heat resistance is greater than 200 &amp;deg;C</td></tr><tr><td>High-temperature resistant silicon pipeline</td><td>Kamoer</td><td>18#</td><td>Temperature range: -60-200 &amp;deg;C</td></tr><tr><td>Infrared Thermogragh</td><td>Hangzhou Meisheng Infrared&lt;br/&gt; Optoelectronic Technology Co., Ltd.</td><td>R60-1009</td><td>Temperature measuring range: -20-410 &amp;deg;C; Maximum measuring error: &amp;plusmn;2 &amp;deg;C</td></tr><tr><td>Padder</td><td>Yabo textile machinery co., Ltd.</td><td></td><td>Roller pressure: 0.03-0.8 MPa; Stable pressure; Easy adjustment</td></tr><tr><td>Personal Computer</td><td>Lenovo Group.</td><td>L460</td><td></td></tr><tr><td>Temperature Sensor</td><td>Taiwan TES electronic industry co., Ltd.</td><td>1311A</td><td>resolution: 1 &amp;deg;C; Temperature measuring range: -50-1350 &amp;deg;C</td></tr></tbody></table>

fabric moisture uniform control to study the influence of air impingement parameters on fabric drying characteristics

Impinging dryness is now a widely used and effective way for fabric drying due to its high heat and mass transfer coefficient. Previous studies on fabric drying have neglected the contributions of moisture uniformity and diffusion coefficient to the drying process; though, they have recently been shown to have a significant influence on drying characteristics. This report outlines a step-by-step procedure to investigate the effects of air impingement parameters on a fabric&#39;s drying characteristics by controlling the uniformity of its area moisture distribution. A hot air blower unit equipped with an angle adjustable nozzle is used to generate air flow with different velocities and temperatures while the drying process is recorded and analyzed using an infrared thermograph. In addition, a uniform padder is adapted to ensure the fabric&#39;s moisture uniformity. Impinging drying is studied under different initial conditions by changing the air flow temperature, velocity, and direction, then the applicability and suitability of the protocol are evaluated.

The data presented in Figure 2 are typical temperature contours for cotton fabric at different drying stages under the condition that air velocity and temperature at the nozzle outlet are 20.0 m/s and 120 &#176;C, respectively. It can be figured from Figure 2A,B,C,D that under the air impingement drying, temperature decays from the center to the periphery and forms sets of concentric circles. Meanwhile, temperatu...

Watch this Scientific Journal Video about Fabric Moisture Uniform Control to Study the Influence of Air Impingement Parameters on Fabric Drying Characteristics at JoVE.com

Fabric Moisture Uniform Control to Study the Influence of Air Impingement Parameters on Fabric Drying Characteristics

Presented here is a protocol that guarantees uniform distribution of initial moisture inside of a fabric and investigates the effects of hot-air thermodynamic parameters (velocity, temperature, and direction) and thickness on the fabric&#39;s drying characteristics (e.g., temperature variation) under the condition of air impingement.

Impinging dryness is now a widely used and effective way for fabric drying due to its high heat and mass transfer coefficient. Previous studies on fabric ...

fabric-moisture-uniform-control-to-study-influence-air-impingement

Research

JoVE Journal

Engineering

5.1K Views.  Zhejiang Sci-Tech University. Presented here is a protocol that guarantees uniform distribution of initial moisture inside of a fabric and investigates the effects of hot-air thermodynamic parameters (velocity, temperature, and direction) and thickness on the fabric's drying characteristics (e.g., temperature variation) under the condition of air impingement.

Video: Fabric Moisture Uniform Control to Study the Influence of Air Impingement Parameters on Fabric Drying Characteristics

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages.

A protocol for the design and construction of a soil tank interfaced to a small climate controlled wind tunnel to study the effects of atmospheric forcings on evaporation is presented. Both the soil tank and wind tunnel are instrumented with sensor technologies for the continuous in situ measurement of environmental conditions.

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study ...

Environment

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds between 0 and 25 m/sec) and a spinning disk device (for examining surface speeds between 15 and 100 m/sec). The air cannon linear traverse is a pneumatic energy-powered system that is designed to accelerate a metal rail surface mounted on top of a wooden projectile. A pressurized cylinder fitted with a solenoid valve rapidly releases pressurized air into the barrel, forcing the projectile down the cannon barrel. The projectile travels beneath a spray nozzle, which impinges a liquid jet onto its metal upper surface, and the projectile then hits a stopping mechanism. A camera records the jet impingement, and a pressure transducer records the spray nozzle backpressure. The spinning disk set-up consists of a steel disk that reaches speeds of 500 to 3,000 rpm via a variable frequency drive (VFD) motor. A spray system similar to that of the air cannon generates a liquid jet that impinges onto the spinning disc, and cameras placed at several optical access points record the jet impingement. Video recordings of jet impingement processes are recorded and examined to determine whether the outcome of impingement is splash, splatter, or deposition. The apparatuses are the first that involve the high speed impingement of low-Reynolds-number liquid jets on high speed moving surfaces. In addition to its rail industry applications, the described technique may be used for technical and industrial purposes such as steelmaking and may be relevant to high-speed 3D printing.

Two experimental devices for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device and a spinning disk device. The apparatuses are used to determine optimal approaches to the application of liquid friction modifier (LFM) onto rail tracks for top-of-rail friction control.

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

Wicking Tests for Unidirectional Fabrics: Measurements of Capillary Parameters to Evaluate Capillary Pressure in Liquid Composite Molding Processes

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify their influence on void formation in composite parts. Wicking in a fibrous medium described by the Washburn equation was considered equivalent to a flow under the effect of capillary pressure according to the Darcy law. Experimental tests for the characterization of wicking were conducted with both carbon and flax fiber reinforcement. Quasi-unidirectional fabrics were then tested by means of a tensiometer to determine the morphological and wetting parameters along the fiber direction. The procedure was shown to be promising when the morphology of the fabric is unchanged during capillary wicking. In the case of carbon fabrics, the capillary pressure can be calculated. Flax fibers are sensitive to moisture sorption and swell in water. This phenomenon has to be taken into account to assess the wetting parameters. In order to make fibers less sensitive to water sorption, a thermal treatment was carried out on flax reinforcements. This treatment enhances fiber morphological stability and prevents swelling in water. It was shown that treated fabrics have a linear wicking trend similar to those found in carbon fabrics, allowing for the determination of capillary pressure.

An experimental method to measure geometrical parameters and the apparent advancing contact angles describing capillary wicking in unidirectional synthetic and natural fabrics is proposed. These parameters are mandatory for the determination of the capillary pressures that must be taken into account for liquid composite molding (LCM) applications.

During impregnation of a fibrous reinforcement in liquid composite molding (LCM) processes, capillary effects have to be understood in order to identify ...

Deposition of Porous Sorbents on Fabric Supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...

Chemistry

Film Control to Study Contributions of Waves to Droplet Impact Dynamics on Thin Flowing Liquid Films

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous studies on flowing liquid films have neglected the contributions of spatial structures of waves to the impact outcome, while this has recently been shown to have a significant influence on the drop impact dynamics. In this report, we outline a step-by-step procedure to investigate the effect of periodic inlet forcing of a flowing liquid film leading to the production of spatiotemporally regular wave structures on drop impact dynamics. A function generator in connection with a solenoid valve is used to excite these spatiotemporally regular wave structures on the film surface while the impact dynamics of uniform-sized droplets are captured using a high-speed camera. Three distinct regions are then studied; viz. the capillary wave region preceding the large wave peak, the flat film region, and the wave hump region. The effects of important dimensionless quantities such as film Reynolds, drop Weber and Ohnesorge numbers parameterized by the film flow rate, drop speed, and drop size are also examined. Our results show interesting, hitherto undiscovered dynamics brought about by this application of film inlet forcing of the flowing film for both low and high inertia drops.

A protocol to study the contributions of waves to droplet impact dynamics on flowing liquid films is presented.

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous ...

Fabrication of an Optical Cell Dryer for the Spectroscopic Analysis Cells

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is performed with a spectroscope. The materials used for optical cells generally include quartz glass or plastic, but expensive quartz glass is reused by removing substances, other than liquids, to be analyzed that adhere to the interior of the container. In such a case, the optical cells are washed with water or ethanol and dried. Then, the next sample is added and measured. Optical cells are dried naturally or with a manual hairdryer. However, drying takes time, which makes it one of the factors that increase the experiment time. In this study, the objective is to drastically reduce the drying time with a dedicated automatic dryer that can dry multiple optical cells at once. To realize this, a circuit was designed for a microcomputer, and the hardware using it was independently designed and manufactured.

A protocol for fabricating a device for simultaneously drying multiple optical cells is presented.

Optical cells, which are experimental instruments, are small, square tubes sealed on one side. A sample is placed in this tube, and a measurement is ...

Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions

Vertical impacts of spheres on clean water have been the subject of numerous water entry investigations characterizing cavity formation, splash crown ascension and Worthington jet stability. Here, we establish experimental protocols for examining splash dynamics when smooth free-falling spheres of varying wettability, mass, and diameter impact the free surface of a deep liquid pool modified by thin penetrable fabrics and liquid surfactants. Water entry investigations provide accessible, easily assembled and executed experiments for studying complex fluid mechanics. We present herein a tunable protocol for characterizing splash height, flow separation metrics, and impactor kinematics, and representative results which might be acquired if reproducing our approach. The methods are applicable when characteristic splash dimensions remain below approximately 0.5 m. However, this protocol may be adapted for greater impactor release heights and impact velocities, which augurs well for translating results to naval and industry applications.

This protocol demonstrates the basic experimental configuration for water entry experiments with free-falling spheres. Methods for the alteration of liquid surface with penetrable fabrics, the preparation of chemically non-wetting spheres, and steps for splash visualization and data extraction are discussed.

Vertical impacts of spheres on clean water have been the subject of numerous water entry investigations characterizing cavity formation, splash crown ...

Study of a Dot-patterning Process on Flexible Materials using Impact Print-Type Hot Embossing Technology

Here we present our study on an impact print-type hot embossing process which can create dot patterns with various designs, widths, and depths in real time on polymer film. In addition, we implemented a control system for the on-off motion and position of the impact header to engrave different dot patterns. We performed dot patterning on various polymer films, such as polyester (PET) film, polymethyl methacrylate (PMMA) film, and polyvinyl chloride (PVC) film. The dot patterns were measured using a confocal microscope, and we confirmed that the impact print-type hot embossing process produces fewer errors during the dot patterning process. As a result, the impact print-type hot embossing process is found to be suitable for engraving dot patterns on different types of polymer films. In addition, unlike the conventional hot embossing process, this process does not use an embossing stamp. Therefore, the process is simple and can create dot patterns in real time, presenting unique advantages for mass production and small-quantity batch production.

Impact print-type hot embossing technology uses an impact header to engrave dot patterns on flexible materials in real time. This technology has a control system for controlling the on-off motion and position of the impact header to create dot patterns with various widths and depths on different polymer films.

Here we present our study on an impact print-type hot embossing process which can create dot patterns with various designs, widths, and depths in real ...

Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and macro-structures, as seen in the cases of moving water in vascular bundles and moisturizing water in skin layers. In this study, we developed a method for assessing the effect of aqueous liquid crystalline (LC) solutions composed of biopolymers on drying. As LC biopolymers have megamolecular weight, we chose to study polysaccharides, cytoskeletal proteins, and DNA. The observation of biopolymer solutions during drying under polarized light reveals milliscale self-integration starting from the unstable air-LC interface. The dynamics of the aqueous LC biopolymer solutions can be monitored by evaporating water from a one-side-open cell. By analyzing the images taken using cross-polarized light, it is possible to recognize the spatio-temporal changes in the orientational order parameter. This method can be useful for the characterization of not only artificial materials in various fields, but also natural living tissues. We believe that it will provide an evaluation method for soft materials in the biomedical and environmental fields.

A method for the drying-induced self-integration of megamolecular biopolymers on the air-liquid crystalline interface is provided here. This methodology will be useful not only for understanding the macroscopic potentials of biopolymers, but also as an evaluation method for soft materials in biomedical and environmental fields.

Living organisms that use water are always prone to drying in the environment. Their activities are driven by biopolymer-based micro- and ...

Bioengineering

Using a Tray Dryer to Investigate Convective and Conductive Heat Transfer

Source: Michael G. Benton and <a href="https://www.jove.com/author/Kerry+M._Dooley">Kerry M. Dooley</a>, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
Dryers are utilized in numerous industrial processes. The function of a dryer is to use heat transfer processes to dry solids. A variety of dryer types exist. Adiabatic dryers use convection and direct contact with gases to dry solids, whereas non-adiabatic dryers use methods other than heated gas contact to dry1, including conduction, radiation, and radio frequency drying1. Dryers can be used for batch processes or they be in continuous use1.
In this experiment, the effects of temperature and air velocity on the drying rate of sand will be determined using a tray dryer. Three different power settings (1000 W, 1500 W and 2500 W) for two different air flow rates will be tested, providing a total of six data sets. From this data, the heat and mass transfer coefficients can be calculated.

Tray Dryer Test to Investigate Convective and Conductive Heat Transfer

Source: Michael G. Benton and Kerry M. Dooley, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA
Dryers are utilized in ...