توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Adaptive Simulated Annealing for Determination of Discrete Relaxation Spectra.
نویسنده(ها): ،
اطلاعات انتشار: نهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۱۱
Adaptive Simulated Annealing (ASA), is a suitable method for determination of discrete relaxation spectra. In this paper, we obtain the discrete relaxation spectra using the AAA algorithm. The method is based on randomly generated trial values of relaxation moduli, i g , and relaxation times, i l . In any stage, the algorithm try to find the best set of relaxation moduli, i g , and relaxation times, i l . Also, it follow to reach the global optimization by passing many local optima. An advantage of the mrthod is that it does not require the function to be smooth (differentiable) or even continuous, which is a requirement for gradient method.The results of this approach is used for obtaining the discrete relaxation spectra of polypropylene and polybutadiene polymer materials from small strain oscillatory shear measurements. Comparing of the algorithm and experimantal results, one can observe the capability of the ASA algorithm to fit a relaxation spectrum with the fewest possile parameter. This method is shownto be robust and reliable.<\div>

۲Discrete Relaxation Spectrum and K–BKZ Constitutive Equation for PVC, NBR and Their Blends
نویسنده(ها): ،
اطلاعات انتشار: هشتمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۱۰
Frequency sweep experiments were performed on poly(vinyl chloride) (PVC) and acrylonitrile butadiene rubber (NBR) as well as their miscible blends; i.e. PVC\NBR by mechanical EOHQGLQJ DW C o . In order to investigate the validity of time temperature superposition (TTS) principle, curves of loss angle ) (d
versus the logarithm of absolute value of complex modulus, *) log( G , have been plotted. It has been shown that the TTS principle is not valid for the above–mentioned polymer materials and therefore, they are not t hermorheologically simple. Meanwhile, master curves of PVC, NBR and PVC\NBR OHQG ZHUH REWDLQHG approximately. Using a nonlinear regression method, discrete relaxation spectra have been determined for 39& 1 %5 DQG 39& 1 %5 7R VWXG non–linear viscoelasticity behavior, the
experiments of steady shear, start up steady shear and step strain have been carried out. The damping function was determined by the step strain experiments. Using K–BKZ equation, the shear viscosity and the shear stress growth function were calculated from the discrete relaxation spectra and the damping function, and then compared to experimental data. The K–BKZ constitutive equation provides very good prediction over the entire range of experimental results, particularly; it predicts the main features of
the experimental data.<\div>

۳Supercritical carbon dioxide extraction of Ferulago Angulata essential oil
اطلاعات انتشار: ششمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۸
The essential oil of aerial parts of Ferulago Angulata was extracted through supercritical fluids technology (CO2). The essential oil was analyzed by GC\MS and GC methods and the total extraction yield was 0.8 percent. The 37 components of the chemical compound of the essence oil have been identified. The 14 main components are included 83.3% and the first 20 ones 94.14% of the total essence. This is the first report representing the extract of Ferulago Angulata. The essence through supercritical method by carbon dioxide and the ultimate amount of its yield in this way is more than the amount extracted through hydro–solvent distillation. Major components including: Suberosin (12.36%), Spathulenol (10.90%), Trans Beta Caryophyllene (7.32%), Arcurcumene (7.07%), and Bicyclogermacrene (6.96%).<\div>

۴The viscosity behavior of ethylene glycol based titania\copper oxide nanofluids
اطلاعات انتشار: چهاردهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۵
Nanofluids are innovative heat transfer fluids engineered by dispersing metallic or non–metallic nanoparticles with typical sizes of less than 100 nm in conventional heat transfer fluids. Theproposed applications of nanofluids have generally been in the heat transfer area where a small concentration of particles often produces an–order–of–magnitude–larger heat transfer enhancement.In this work the rheological responces of ethylene glycol based titania\copper oxide nanofluids at0%, 0.5%, 3% and 10% wt (at equal concentration) were obtained at different particle concentration, temperature and shear rates. The viscosity of nanofluids was measured by arotational viscometer whiched equiped by a thermal bath over the shear rate range of 0.5 to 200 s–1 and temperature from 280 k to 340 k. The results show the Newtonian behavior over the wholerange of viscosity and temparature. The viscosity is affected strongly on particle concentration and temperature. For example, the viscosity increases from 21.5 mPa.s to 29 mPa.s at 40°C when 10% wt nanoparticles added to pure EG. The similar observation can be found for other concentration. Interestingly, the viscosity growth is independent of temperature and may be displayed by only a concentration–based equation. The increase of viscosity (normalized viscosity) can be well estimated by a power–law equation with constant factors<\div>

۵A rheological approach to investigate the shear rate effect on the viscosity of silicon carbide\engine coolant nanofluids
اطلاعات انتشار: چهاردهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۶
Cooling and lubricating are important in many industries, especially in transportation and energy production. Nanofluids are designed by adding nanoscale particles in low volumetric fractions to afluid in order to enhance or improve its rheological, mechanical, optical, and thermal properties.The liquid phase can be any liquid such as oil, water, ethylene glycol, or conventional fluidmixtures. The present paper, describes our experimental results on the viscosity of the nanofluidprepared by dispersing SiC nanoparticles (<100 nm) in commercial car coolant. The viscosity of the nanofluids is measured both as a function of SiC volume fraction and temperature between 10°C and 60°C. While the pure base fluid display Newtonian behavior over the measuredtemperature, it transforms to a non–Newtonian fluid with addition of a small amount of SiC nanoparticles. The temperature dependence of the viscosity of engine coolant based SiC nanofluids obeys the empirical correlation of the type: log (?f) = A exp (BT), proposed earlier by Namburu et al<\div>

۶The rheological and thermal behavior of CuO in ethylene glycol –water nanofluids
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۱۰
In this work, copper oxide nanofluids have been prepared by adding 2%, 4% and 6% (vol\vol) into the ethylene glycol\water mixture (60:40) for measuring the viscosity and thermal experiments. The mixing section was carried out by ultrasonic bath. By using the well–known hot wire methodthe thermal behavior of nanofluids has been studied. The results show that the ratio of thermalconductivity reaches to 1.15, 1.26 and 1.31 after adding 2%, 4% and 6% nanoparticles,respectively. The thermal behavior of nanofluids was studied by Maxwell, Bruggeman and Koo and Klenstreuer models. Among the applied models, the latter one can better predict the experimental data. In another part of this work, the viscosity of samples was measured by amodern Brookfield rheometer at ranging from 5 s–1 to 200 s–1 and from –5°C to 40°C. The results indicate that the base flow shows Newtonian behavior over the whole range of shear rates and temperatures. But the nanofluids are switching to Non–Newtonian behavior. This effect can beenhanced at lower temperatures. The viscosity\shear rate data was modeled by Sisko model and then the parameter of n, K and infinite viscosity has been calculated. The viscosity is going to decrease by increasing the temperature. At the end, this behavior was studied by exponential form which suggested by Namburu et al. Based on this model, the fitting parameters of A and B were then extracted that can predict the experimental data very well<\div>

۷Sulfonated polyacrylamide adsorption onto carbonate reservoir rock at high temperature
اطلاعات انتشار: پانزدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۴
Adsorption behavior of polymer on reservoir rock is important for its application in enhanced oil recovery.Adsorption of polymer on reservoir rock makes the polymer concentration decreases in the aqueous phase and therefore reduces the viscosity and sweep efficiency of the injected polymer solution. In this study, the adsorption behavior of SPAA solutions on the carbonate rock particles at high temperature were investigated.The influence of experimental parameters, such as time contact, polymer concentration and salinity were investigated. According to the experimental results, the polymer adsorption increased with increasing SPAA concentration, but decreased with increasing water salinity. Adsorption of polymer in the presence of anionic surfactant, e.g. Sodium Lauryl Ether Sulfate (SLES), was also evaluated.<\div>
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