Evaluation of thermal stability of quasi-isotropic composite/polymeric cylindrical structures under extreme climatic conditions

Mohamed Gadalla,Hany El Kadi 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.3

Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

Effect of surfactants on the stability and solar thermal absorption characteristics of water-based nanofluids with multi-walled carbon nanotubes

Choi, Tae Jong,Jang, Seok Pil,Kedzierski, M.A. Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.122 No.-

<P><B>Abstract</B></P> <P>This paper reports the effect of various surfactants on the suspension stability and the solar thermal absorption characteristics of water-based nanofluids containing multi-walled carbon nanotubes (MWCNTs) that can be used as working fluids for volumetric solar thermal receivers. The water-based MWCNT nanofluids were prepared using a two-step method with four commonly used surfactants: sodium dodecylbenzenesulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX-100). The stability of the four surfactant-treated nanofluids was analyzed for over a month with an in-house developed laser transmission system. The effect of temperature on the stability of the nanofluid/surfactant mixtures was also examined. In addition, to identify the absorption characteristics of the four nanofluids, the spectral extinction coefficients were measured using an UV–Vis–NIR spectrophotometer. The absorbed sunlight fraction was calculated using the measured spectral extinction coefficient, which enabled an evaluation of the absorption characteristics of the nanofluids. The MWCNT nanofluids were clearly shown to enhance the absorption rate of solar thermal energy. The suspension stability and the absorption characteristics were also strongly affected by the type of surfactant. Moreover, using the absorbed sunlight fraction and suspension-stability factor, we experimentally show the relation between the absorption characteristics and suspension stability in nanofluids.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of surfactants on suspension stability and absorption are reported. </LI> <LI> The relation between absorption and suspensions stability of nanofluids is presented. </LI> <LI> MWCNTs nanofluids with SDBS have a high extinction coefficient and suspension stability. </LI> </UL> </P>

고추씨유, 캡사이신 및 토코페롤의 첨가가 돈지와 대두유의 산화안정성에 미치는 영향

이치호,한규호,김아영,이슬기,홍고은,변장원,최강덕,양철영,Lee, Chi-Ho,Han, Kyu-Ho,Kim, Ah-Young,Lee, Seul-Ki,Hong, Go-Eun,Pyun, Chang-Won,Choi, Kang-Duk,Yang, Cheul-Young 한국축산식품학회 2008 한국축산식품학회지 Vol.28 No.5

This study was designed to compare the thermal oxidative stability of lard, soy bean oil, and hot pepper seed oil for 0-3 d at $100^{\circ}C$, and to evaluate the effect of capsaicin on thermal oxidative stability in lard and soy bean oil. As result, thermal oxidation stability was shown in the order hot pepper seed oil>soy bean oil>lard for 0-3 d at $100^{\circ}C$. In blended oils, hot pepper seed oil effectively inhibited lipid oxidation when mixed with lard than soy bean oil by showing the ratio of 30% pepper seed oil plus 70% lard and 60% pepper seed oil plus 40% soy bean oil inhibited lipid oxidation during storage periods. And to investigate the antioxidative effect of antioxidants such as capsaicin and alpha-tocopherol in hot pepper seed oil, 1,200 and 2,400 ppm capsaicin, or 0.3% alpha-tocopherol were added in soy bean oil and lard and stroed for 0-3 d at $100^{\circ}C$. Capsaicin inhibited lipid oxidation in lard but not in soy bean oil, however alpha-tocopherol exhibited a prooxidaton effect in soybean oil. Therefore, it suggests that the application of hot pepper seed oil or capsaicin in lard may be better for thermal oxidative stability.

Thermal stability of oil-in-water Pickering emulsion in the presence of nanoparticle, surfactant, and polymer

Tushar Sharma,G. Suresh Kumara,전보현,Jitendra S. Sangwai 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.22 No.-

Pickering emulsion offers potential applications in several fields including oil and gas industry due totheir enhanced stability. Oil-in-water (o/w) emulsions are usually stabilized by surfactant ornanoparticle or by both but show poor thermal stability which limits their use for high-temperatureapplications. In this work, a novel formulation of o/w emulsion stabilized using nanoparticle-surfactantpolymersystem is investigated for the formulation of thermally stable Pickering emulsion. Theconventional oilfield polymer polyacrylamide (PAM), surfactant, sodium dodecylsulfate (SDS), andnanoparticles such as, SiO2, clay, and CuO in varying concentration are used. It is observed that thenanoparticle in the presence of surfactant and polymer synergistically interacted at the oil–waterinterface. The effect of temperature, pH, and salinity on the interfacial tension is investigated tounderstand the thermal stability. The emulsion system with partially hydrophobic clay nanoparticles inthe presence of PAM and SDS shows higher thermal stability as compared to fully hydrophilic SiO2nanoparticles. In the presence of salt, NaCl (1.0 wt%), the thermal stability of clay and SiO2 stabilizedemulsions is observed to be further promoted at higher temperatures. Scanning electron microscopy(SEM) images confirm the existence of a structured and rigid layer of nanoparticle at the oil–waterinterface.

Evaluation of thermal stability of quasi-isotropic composite/polymeric cylindrical structures under extreme climatic conditions

Gadalla, Mohamed,El Kadi, Hany Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.32 No.3

Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

Thermal stability of oil-in-water Pickering emulsion in the presence of nanoparticle, surfactant, and polymer

Sharma, T.,Kumar, G.S.,Chon, B.H.,Sangwai, J.S. Korean Society of Industrial and Engineering Chemi 2015 Journal of industrial and engineering chemistry Vol.22 No.-

Pickering emulsion offers potential applications in several fields including oil and gas industry due to their enhanced stability. Oil-in-water (o/w) emulsions are usually stabilized by surfactant or nanoparticle or by both but show poor thermal stability which limits their use for high-temperature applications. In this work, a novel formulation of o/w emulsion stabilized using nanoparticle-surfactant-polymer system is investigated for the formulation of thermally stable Pickering emulsion. The conventional oilfield polymer polyacrylamide (PAM), surfactant, sodium dodecylsulfate (SDS), and nanoparticles such as, SiO<SUB>2</SUB>, clay, and CuO in varying concentration are used. It is observed that the nanoparticle in the presence of surfactant and polymer synergistically interacted at the oil-water interface. The effect of temperature, pH, and salinity on the interfacial tension is investigated to understand the thermal stability. The emulsion system with partially hydrophobic clay nanoparticles in the presence of PAM and SDS shows higher thermal stability as compared to fully hydrophilic SiO2 nanoparticles. In the presence of salt, NaCl (1.0wt%), the thermal stability of clay and SiO2 stabilized emulsions is observed to be further promoted at higher temperatures. Scanning electron microscopy (SEM) images confirm the existence of a structured and rigid layer of nanoparticle at the oil-water interface.

Study of Thermal Stability of Ni Silicide using Ni-V Alloy

Zhun Zhong,Soon-Young Oh,Won-Jae Lee,Ying-Ying Zhang,Soon-Yen Jung,Shi-Guang Li,Ga-Won Lee,왕진석,이희덕,Yeong-Cheol Kim 한국전기전자재료학회 2008 Transactions on Electrical and Electronic Material Vol.9 No.2

In this paper, thermal stability of Nickel silicide formed on p-type silicon wafer using Ni-V alloy film was studied. As compared with pure Ni, Ni-V shows better thermal stability. The addition of Vanadium suppresses the phase transition of NiSi to NiSi₂ effectively. Ni-V single structure shows the best thermal stability compared with the other Ni-silicide using TiN and Co/TiN capping layers. To enhance the thermal stability up to 650 ˚C and find out the optimal thickness of Ni silicide, different thickness of Ni-V was also investigated in this work.

Research Note : The Role of Glucosides on the Thermal Stability of Color Produced by Anthocyanins from Red Cabbage

( J. Michelle Lee ),( Moonsoo Jin ) 한국산업식품공학회 2015 산업 식품공학 Vol.19 No.2

Carbohydrate derivatives of cyanidin, a class of anthocyanin pigments, are major component of red cabbage, which is responsible for the characteristic reddish color. The color of cyanidin derivatives is quite stable against heat, and here we aimed to identify the chemical component of glucoside-derivatives of cyanidin which is responsible for the thermal stability. By comparing the thermal stability of color from unmodified cyanidin and cyanidin-3,5 diglucoside with the color of cyanidin derivatives from red cabbage, we found that the glucoside modification confers the thermal stability. We believe that our finding will contribute to the preparation of heat-resistant anthocyanin pigments for food coloring and other applications.

Influence of salt, solvents, and additives on the thermal stability of delithiated cathodes in lithium-ion batteries

Lee, Yongho,Kim, Sang-Ok,Mun, Junyoung,Park, Min-Sik,Kim, Ki Jae,Lee, Kwan Young,Choi, Wonchang Elsevier S.A 2017 Journal of Electroanalytical Chemistry Vol.807 No.-

<P><B>Abstract</B></P> <P>The thermal stability of a fully delithiated cathode, coupled with an inorganic salt, organic solvents, and electrolyte, was evaluated with differential scanning calorimetry (DSC) to address the safety issue of lithium-ion batteries. The DSC experiments revealed that vinylene carbonate (VC)-based systems exhibit decreased thermal stability compared to other coexisting systems. The DSC analysis of the cathode and electrolyte in the presence of VC, employed as additives, confirmed the reduction in thermal stability. Our results suggested that VC additives, which have been recently employed to enhance the electrochemical performance in anodes, negatively affect the thermal properties and safety characteristics of the cathode in lithium-ion batteries.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Studied thermal stability of delithiated cathodes and electrolyte components by using DSC </LI> <LI> This study helps address the issue of safety of lithium-ion batteries. </LI> <LI> VC additives are previously known to enhance the performance of the anode. </LI> <LI> Therefore, systems based on VC additive show a decreased thermal stability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

FTIR evaluation on the fuel stability of calophyllum inophyllum biodiesel: Influence of tert-butyl hydroquinone (TBHQ) antioxidant

Mohamed Shameer P.,Ramesh K. 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.7

‘Storage oxidation stability’ is one of the most significant criteria for appraising the biodiesel quality. Poor oxidation stability is the chief technical blockage related with the commercialization of biodiesel. The present paper investigates the effects of Tert- butyl hydroquinone (TBHQ) antioxidant additive concentrations on the long-term storage stability, thermal stability and accelerated oxidation stability of Calophyllum inophyllum biodiesel. Fourier transform infra-red (FTIR) spectroscopy was used to characterize the biodiesel oxidation variability, following the regions of C-H and O-H bonds in FTIR spectrum for different concentrations of TBHQ. Addition of TBHQ at 1000 ppm concentration (B100A3) with pure biodiesel enhances the oxidation stability by 94.67 %, storage stability by 14.47 % and thermal stability by 69.55 %; whereas further concentration of antioxidant deteriorates the formation of hydrophobic and hydrophilic clusters between biodiesel/antioxidant compounds, which is characterized by FTIR spectrum data. It is concluded that the Calophyllum inophyllum biodiesel could be accumulated for an extensive period by dosing 1000 ppm of TBHQ antioxidant.