Browsing by Author "Yang, Tao"
Now showing 1 - 13 of 13
Results Per Page
Sort Options
- ItemAn experimental evaluation of convective heat transfer in multi-layered fibrous materials composed by different middle layer structures(SAGE PUBLICATIONS INC, 2455 TELLER RD, THOUSAND OAKS, CA 91320 USA, 2019-10) Xiong, Xiaoman; Venkataraman, Mohanapriya; Jašíková, Darina; Yang, Tao; Mishra, Rajesh; Militký, Jiří; Petrů, MichalIn this work, three types of multi-layered fibrous materials with different middle layer structures, including Struto nonwoven, Struto nonwoven with air pockets and Struto nonwoven with air pockets filled by aerogel particles, were prepared based on laser engraving technique and laminating method. A custom-built new device was fabricated to evaluate convective thermal behaviour of the multi-layered materials in cross flow. It was found that in cross flow the heat transfer coefficient of the multi-layered material with encapsulated aerogels is directly proportional to Reynolds number. There are considerable variances in heat transfer rates of the three structures at low airflow velocity (less than 10 m/s), but the values are very close at high airflow velocity. It is concluded that the air pockets and aerogels present in the multi-layered fibrous material have significant effect on convective thermal behaviour of the overall structure in cross flow. The finding is a new contribution to the field of aerogel-based fibrous materials as thermal insulators in building and industrial facilities.
- ItemElectrical Heating Properties of Carbon Fabric/Green Epoxy Composites Filled with Fly Ash(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Wang, Yuan-Feng; Karthik, Daniel; Yang, Kai; Yang, Tao; Xiong, Xiao-Man; Baheti, Vijay; Militký, JiříThis paper investigates the joule heating behavior and electrical property of the carbon fabric/green epoxy composite laminates filled with various concentrations of unmilled fly ash and milled fly ash. The infrared camera was used to record the change in surface temperature of composites over a period of time (i.e. from 0 to 240 sec) by varying the voltage from 0 to 10 V. The results show that the composite containing 0.5% fly ash exhibited the maximum temperature under different applied voltages. The maximum temperatures of epoxy/carbon composites could be finely tuned by controlling the concentrations of fly ash fillers as well as the applied voltage. When a certain voltage was applied to the composite, the surface composite temperature reached the maximum and became stable at a time shorter than 120s. In addition, the milled fly ash filled epoxy/carbon composites were found to reveal improvement in electrical heating performance and structural stability over the unmilled fly ash filled composites.
- ItemInvestigation on sound absorption properties of aerogel/polymer nonwovens(2019-02-01) Yang, Tao; Xiong, Xiaoman; Venkataraman, Mohanapriya; Mishra, Rajesh; Novák, Jan; Militký, JiříThis paper presents an investigation on sound absorption performance of aerogel/polymer nonwoven fabrics. Polyester/polyethylene nonwovens embedded with hydrophobic amorphous silica aerogel were chosen for sound absorption measurements. The sound absorption coefficient (SAC) of single and laminated layers of aerogel nonwovens blankets was tested by Bruel and Kj AE r impedance tube, the noise reduction coefficient (NRC) was used for numerical analysis. A sound absorption index was developed to analyze the effect of aerogel content on sound absorption ability. The effect of air-back cavities on SAC of single-layer aerogel/polymer nonwoven fabrics was investigated. The results show that there is a decrease in SAC with the increase of aerogel content. It is observed that the NRC linearly increased with the increase of layers for all the samples. It was also found that the air-back cavities result in resonance phenomenon, as the increase in thickness of air-back cavities the peak values of SAC shift toward lower frequencies.
- ItemNumerical Modelling of the Acoustic Properties of Polyester Non-woven(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Yang, Tao; Saati, Ferina; Xiong, Xiao-Man; Wang, Yuan-Feng; Yang, Kai; Mishra, Rajesh; Militký, Jiří; Petrů, MichalThis paper investigates the acoustical properties of polyester non-woven by using practical and numerical methods. Several types of non-woven samples made from staple, hollow and bi-component polyester fibres were chosen to carry out this study. The AFD300 Acoustic Flow device was used to measure airflow resistivity. The 45 mm Materiacustica two-microphone impedance tube was used to measure the surface impedance and sound absorption coefficient. Widely used impedance models, such as the Delany-Bazley, Miki, Garai-Pompoli and Komatsu models, were applied to predict acoustical properties. A comparison between measured and predicted values has been performed to derive the most accurate model. The Johnson-Champoux-Allard-Lafarge (JCAL) model was applied to obtain some non-acoustical properties based on the inverse method. It is found that the Delany-Bazley and Miki models can accurately predict the surface impedance of polyester non-woven. The results indicate that the Miki model is the most acceptable method for predicting the sound absorption coefficient, with an 8.39% mean error for all of the samples. The values are 8.92%, 12.58% and 69.67% for the Delany-Bazley, Garai-Pompoli and Komatsu models, respectively. Several difficult-to-obtain parameters have been investigated.
- ItemPokročilé vlákenné materiály pro akustický výkonYang, Tao; Mishra Rajesh, doc. Ph.D. Skolitel : 60165Cílem této práce bylo prozkoumat multifunkční vlastnosti vysocepevnostních kolmo kladených netkaných textilií, které mohou být použity k redukci hluku při stavebnictví a v automobilovém průmyslu. Práce představuje experimentální a numerické vyšetřování akustických vlastností rohoží kladených na sobě. Normální koeficient absorpce zvuku a povrchová impedance byly měřeny impedanční trubkou typu Brüel a Kj?r 4206. Ke studiu vhodného modelu pro rovné kladené netkané textilie bylo použito několik modelů odporového proudu vzduchu seskupených v teoretických i empirických kategoriích. Pro předpovědi akustických vlastností byly použity běžně používané impedanční modely jako modely Delany-Bazley, Miki, Garai-Pompoli a Komatsu. Naměřené a předpovězené hodnoty byly porovnány s výpočtem přesnosti stávajících modelů. Jeden jednoduchý model byl vyvinut pro rychlé získání odporového proudu vzduchu kolmých kladených netkaných textilií.Vzorky z netkaného materiálu byly provedeny dvěma různými výrobními technikami: vibracemi a rotačními kolíčky. Metoda tepelného lisování byla použita pro tvorbu vzorků s různou tloušťkou a plošnou hustotou. Tato studie určuje vliv různých strukturních charakteristik a výrobních technik na vlastnosti absorpce zvuku kolmo kladených netkaných textilií.Kompresní energie a zatížení stlačením kolmo kladených netkaných textilií byly provedeny univerzálním zkušebním strojem (TIRATEST 2300). Potenciální kompresní mechanismus netkané textilie byl identifikován s podporou kompresní křivky napětí-deformace, práce a účinnosti v různých kompresních stupních.Pásky s kolmými vrstvami mají zvláštní tepelnou a vzduchovou propustnost ve srovnání s tradičními netkanými nitěmi, které jsou způsobeny jejich orientací přes vlákna. Proto tato výzkumná práce také zkoumá vliv různých strukturálních parametrů rohože kladených netkaných textilií, jako je plošná hustota, pórovitost, tloušťka, na tepelné vlastnosti a propustnost vzduchu. Rovněž byly zkoumány potenciální vztahy mezi tepelným odporem, propustností pro vzduch a akustickými vlastnostmi.Aerogel má vysokou porovitost (> 90%), vysokou specifickou plochu, nízkou hmotnost a nízkou rychlost zvuku (až 90 m / s). Vzhledem k těmto vlastnostem mohou být aerogely použity v oblastech pohlcování a tepelné izolace. Tato diplomová práce taktéž zkoumala výkonnost absorpce zvuku vzduchových / polymerních netkaných textilií. Pro měření zvukové pohltivosti byly vybrány polyesterové / polyethylenové netkané textilie opatřené hydrofobním amorfním oxidem křemičitým. Koeficient absorpce zvuku (SAC) jednotlivých a vrstvených vrstev vzduchových netkaných textilií byl testován impedanční trubkou Brüel a Kj?r.K provádění všech statistických výsledků v této studii byl použit statistický analytický software Originlab 8.5 a Matlab_R2017a. Výsledky jsou významná a mohou být použity pro další studium v oblastech zvukového absorpčního chování vláknitých materiálů, aplikaci kolmo kladených netkaných textilií pro pro zpracování hluku v budovách a automobilových polích.
- ItemPorous Film Coating Enabled by Polyvinyl Pyrrolidone (PVP) for Enhanced Air Permeability of Fabrics: The Effect of PVP Molecule Weight and Dosage(2020) Jiang, Jiantang; Shen, Yifeng; Yu, Deyou; Yang, Tao; Wu, Minghua; Yang, Lei; Petrů, MichalThis study developed a versatile and facile method for creating pores and tuning the porous structure in the polymer latex films by selectively etching the added functional polyvinyl pyrrolidone (PVP) molecules. The pore formed in the latex films had a similar morphology to that of PVP aggregation before etching. This observation promotes us to regulate the pore morphology that determines the film’s property, such as air permeability through varying the PVP molecule weight and dosage. To this end, the effects of PVP molecule weight and dosage on the pore formation were systematically studied. The results showed that the average pore size of porous film decreased from >10 μm to sub-micron (about 0.4 μm) as the molecular weight or the dosage of PVP increased. This was ascribed to the strong adsorption affinity of PVP molecule onto the latex particle surface, which further hindered the diffusion and self-assembly of PVP molecule. In addition, this interaction became much stronger when the higher molecule weight of PVP or the higher dosage of PVP was employed, leading to the decreased size of PVP aggregation, as well as the formed pores in the latex films. Furthermore, the addition of PVP had little effect on the color of coated fabric based on the results of CIE L*a*b* measurement. The proposed facile method can be used to improve the air permeability of coated fabrics.
- ItemSound absorption and compression properties of perpendicular-laid nonwovens(SAGE PUBLICATIONS LTD, 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND, 2019-02) Yang, Tao; Xiong, Xiaoman; Mishra, Rajesh; Novák, Jan; Militký, JiříThis study presents an investigation into the sound absorption behavior and compression properties of perpendicular-laid nonwovens. Seven types of perpendicular-laid nonwovens produced by vibrating and rotating perpendicular lappers were selected. Nonwovens with varying thickness and areal density were prepared by the heat-pressing method to investigate the effect of structural parameters such as thickness and areal density on sound absorption ability. Measurements of sound absorption properties were carried out with a Bruel and Kj AE r measuring instrument. The effect of manufacturing techniques on sound absorption performance and compression properties was investigated. The effect of porosity on sound absorption ability was studied. The influence of density and fiber orientation angle on compression properties was analyzed. The results show that samples prepared by vibrating perpendicular lapper exhibit better compression properties, whereas there is no significant influence of two manufacturing techniques on sound absorption performance. The increase of areal density results in improvement in the sound absorption ability. The increase of thickness can improve the sound absorption coefficient in the low-frequency range, but decrease of the coefficient occurred in the high-frequency range. A quadratic relationship between porosity and sound absorption ability has been found. The results also show that compressional resistance has a strong relation with density - the correlation coefficient is 0.95, indicating that the compressional resistance is directly proportional to the density of perpendicular-laid nonwovens. The results indicate that the perpendicular-laid nonwovens with higher initial fiber orientation angle have better compression properties.
- ItemSound Absorption Properties of Natural Fibers: A Review(MDPI, 2020) Yang, Tao; Hu, Lizhu; Xiong, Xiaoman; Petrů, Michal; Noman, Muhammad Tayyab; Mishra, Rajesh; Militký, JiříIn recent years, in an attempt to substitute the conventional synthetic sound absorption material, natural fibers and their sound absorption properties have been increasingly studied. This is due to the fact that conventional synthetic fiber has potential health risks for human beings and significant environmental impact. In this review, existing and newly emerging natural fiber sound absorbers are summarized and highlighted in three categories: raw material, fiber assembly and composite. The sound absorption mechanism, several widely used prediction models and the popular acoustic characterization methods are presented. The comparison of sound absorption properties between some natural sound absorbers and glass fiber is conducted in two groups, i.e., thin material and thick material. It is found that many natural fibers have comparable sound absorption performance, some of them can be the ideal alternatives to glass fiber, such as kapok fiber, pineapple-leaf fiber and hemp fiber. Last, the conclusion part of this review gives an outlook regarding the promotion of the commercial use of natural fiber by means of theoretical study, efficient and environmentally friendly pretreatment and Life Cycle Assessment.
- ItemStudy on the sound absorption behavior of multi-component polyester nonwovens: experimental and numerical methods(2019-08) Yang, Tao; Saati, Ferina; Horoshenkov, Kirill V.; Xiong, Xiaoman; Yang, Kai; Mishra, Rajesh; Marburg, Steffen; Militký, JiříThis study presents an investigation of the acoustical properties of multi-component polyester nonwovens with experimental and numerical methods. Fifteen types of nonwoven samples made with staple, hollow and bi-component polyester fibers were chosen to carry out this study. The AFD300 AcoustiFlow device was employed to measure airflow resistivity. Several models were grouped in theoretical and empirical model categories and used to predict the airflow resistivity. A simple empirical model based on fiber diameter and fabric bulk density was obtained through the power-fitting method. The difference between measured and predicted airflow resistivity was analyzed. The surface impedance and sound absorption coefficient were determined by using a 45 mm Materiacustica impedance tube. Some widely used impedance models were used to predict the acoustical properties. A comparison between measured and predicted values was carried out to determine the most accurate model for multi-component polyester nonwovens. The results show that one of the Tarnow model provides the closest prediction to the measured value, with an error of 12%. The proposed power-fitted empirical model exhibits a very small error of 6.8%. It is shown that the Delany-Bazley and Miki models can accurately predict surface impedance of multi-component polyester nonwovens, but the Komatsu model is less accurate, especially at the low-frequency range. The results indicate that the Miki model is the most accurate method to predict the sound absorption coefficient, with a mean error of 8.39%.
- ItemTheoretical and Experimental Studies on Thermal Properties of Polyester Nonwoven Fibrous Material(MDPI, 2020-06-26) Yang, Tao; Xiong, Xiaoman; Petrů, Michal; Tan, Xiaodong; Kaneko, Hiroki; Militký, Jiří; Sakuma, AtsushiPolyester nonwoven fibrous material is widely used in construction and automobile industries for thermal insulation purposes. It is worthy and meaningful to understand the effect of structural parameters on the thermal property. Fiber orientation, as one of the most vital parameters, has a significant effect on thermal property. However, there has been little quantitative analysis focusing on this aspect. This paper theoretically and experimentally analyzes the thermal conductivity of samples with varying fiber orientation. Existing models were selected to predict the thermal conductivity of polyester nonwoven samples. Two different apparatus were applied to carry out the experimental measurements. The relative differences between the predicted and measured results were compared. One commonly used model was modified for accurate prediction. It was shown that some existing models under- or overestimate the thermal conductivity compared to the measured values. The results indicate that the modified model can accurately predict the thermal conductivity of polyester nonwoven materials within a 0.2% relative difference.
- ItemThermal Behaviour of Multi-layer Composite Containing PEG and Laponite as PCM(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Yang, Kai; Venkataraman, Mohanapriya; Wang, Yuan-Feng; Xiong, Xiao-Man; Yang, Tao; Wiener, Jakub; Militký, Jiří; Mishra, Rajesh; Marek, Jaromír; Zhu, Guo-Cheng; Yao, Ju-MingPolyethylene glycol (PEG) and laponite were prepared together as PCM and a multi-layer composite containing this PCM was developed, consisting of a PCM loaded layer, a nano barrier layer and a protective layer. SEM was used to observe the structure of multi-layer composites containing PCM, with better adhesion observed between the PCM loaded layer, the nano barrier layer and the protective layer. DSC revealed the melting temperature, the cooling temperature and the enthalpy of PEG and laponite as PCM. The multi-layer composite containing PCM was obtained. Laponite functionalized as a nucleating agent to accelerate the crystallization of PEG and 15wt% LP in PCM resulted in a disordered PEG molecular. The composites with more laponite had the higher thermal insulation.
- ItemThermal Performance of Kevlar Woven Fabrics Coated with Silica Aerogel(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Venkataraman, Mohanapriya; Xiong, Xiao-Man; Yang, Tao; Yang, Kai; Wang, Yuan-Feng; Mishra, Rajesh; Militký, JiříKevlar woven fabrics coated with aerogel particles were fabricated via blade coating. Fly ash nanoparticles were incorporated to investigate their effect on thermal performance. Thermal behavior of the prepared fabrics was evaluated and compared by using different techniques. It is found that the aerogels combined with a Kevlar fabric resulted in reduced thermal conductivity and higher thermal resistance. The fly ash coating brought a rapid rise in thermal absorptivity of the overall structure. Under laser radiation with high temperature, the aerogel content played a vital role on the surface temperature of the fabrics. At laser radiations with pixel time 330 mu s, the surface temperatures of the aerogel coated Kevlar fabrics were 400-440 degrees C lower than the uncoated fabric. The results also indicate that the fabric temperature is directly proportional to pixel time. It can be concluded that the Kevlar fabrics coated with silica aerogel provides better thermal protection under high temperature.
- ItemTransport Properties of Electro-Sprayed Polytetrafluoroethylene Fibrous Layer Filled with Aerogels/Phase Change Materials(MDPI, 2020) Xiong, Xiaoman; Venkataraman, Mohanapriya; Yang, Tao; Kučerová, Klára; Militký, Jiří; Yang, Kai; Zhu, Guocheng; Yao, JumingThis work is the first attempt to prepare microporous polytetrafluoroethylene (PTFE) fibrous layers embedded with aerogels/phase change materials. For preparation of this layer, the needle-less electrospray technology of water dispersion of individual components is used. Microstructure characteristics, including surface morphology and particle size distribution, and various properties of the prepared materials were investigated and explained. Transport performance of the fibrous layers embedded with aerogels/phase change materials, such as the transmission of heat, air, and water vapor was evaluated and discussed in details. It was found that the electro-sprayed materials composed by spherical particles with rough surface had compact disordered stacking structure. Aerogels and phase change materials (PCMs) play different roles in determining structural parameters and transport properties of the materials. Those parameters and properties could be flexibly adjusted by optimizing the spinning parameters, changing the content or proportion of the fillers to meet specific requirements.