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1

Evaluation of the effect of rotational speed and rheological nature on heat transfer of complex fluid between two cylinders

Benmansour Abdelhalim, Laidoudi Houssem

Archives of Thermodynamics

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2024

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Vol. 45, no 1

65--73

EN

This paper presents numerical results for flow behavior between a cold inner cylinder and a hot outer cylinder. Both cylinders are placed horizontally. The space separating the two compartments is completely filled with a fluid of a complex rheological nature. In addition, the outer container is subjected to a constant and uniform rotational speed. The results of this work were obtained after solving the differential equations for momentum and energy. The parameters studied in this research are: the intensity of thermal buoyancy, the speed of rotation of the outer container and the rheological nature of the fluid. These elements are expressed mathematically by the following values: Richardson number (Ri = 0 and 1), Reynolds number (Re = 1 to 40), power-law number (n = 0.8, 1 and 1.4) and Prandtl number (Pr = 50). The results showed that the speed of rotation of the cylinder and the rheological nature of the fluids have an effective role in the process of heat transfer. For example, increasing the rotational speed of the enclosure and/or changing the nature of fluid from shearthickening into shear-thinning fluid improves the thermal transfer rate.

2

Rheological behavior of polymer-based drilling fluids: experimental study of temperature effects

Safi Brahim, Aboutaleb Djamila, Haider Soumya

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 1

95--104

EN

Drilling fluids most commonly used are generally based on polymers. Polymers such as methylcellulose carboxylate (CMC), polyanionic cellulose (PAC) and xanthan (Xn) have a very important role in the success of drilling operations. Indeed, they are also used to improve certain properties, in particular rheological. However, these polymers can lose their characteristics under the influence of increasing temperature at the bottom of oil wells, thus affecting the ability of the mud to perform its useful role in the drilling operation, namely to raise the cuttings from the bottom of the well to the surface. The present work aims to study the effect of temperature on the main rheological properties (shear stress and plastic viscosity) as well as on the rheological behavior of water-based drilling muds (WBM). WBM_CMC and WBM_PAC (at Xn content fixed) were selected to evaluate the temperature effect (20°C; 40°C; 60°C and 80°C) on the rheological parameters and the rheological behavior. The results revealed that the shear stress and the plastic viscosity of the studied muds were considerably affected by an increase in temperature. A significant decrease in these drilling mud parameters as a function of temperature up to 80°C. A reduction of 58.8% in shear stress and 78.5% in plastic viscosity was observed. The results show that regardless of the test temperature, the shear thinning behavior of the WBM_CMC and WBM_PAC drilling muds is the same as the Herschel-Bulkley model.

3

Compositions of unsaturated polyester resins used for facing layers of laminates

Oliwa Rafał

Polimery

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2020

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T. 65, nr 10

738--742

EN

Hybrid composites of unsaturated polyester resin with the addition of glass microspheres and bentonite modified with a quaternary ammonium salt were obtained. The content of bentonite in composites was 3 wt %, while glass microspheres varied in the range of 5–15 wt %. The effect of the addition of glass microspheres on the rheological and mechanical properties of unsaturated polyester resin composites containing modified bentonite was investigated. On the basis of the obtained results, it was found that the optimum content of glass microspheres in polyester composites at which a clear increase in the value of most mechanical parameters was achieved, is 15 wt %. The Young’s modulus, flexural modulus, tensile strength, and Charpy impact strength increased by 14.7, 38.7, 17.7 and 25%, respectively, compared to the unmodified resin. On the other hand, with relation to the sample containing 3 wt % of bentonite, a significant improvement was achieved only in the case of the flexural modulus and impact strength, amounting to 16.5 and 36.0%, respectively. In addition, composite with 15 wt % of glass microspheres was characterized by a smaller, by about 25%, flexural strength in relation to the unfilled resin and resin with 3 wt % of bentonite. In turn, rheological studies have shown that as the content of glass microspheres increased, there was an increase in viscosity and a decrease in gelation time in relation to the reference sample and the sample with 3 wt % of bentonite.

PL

Otrzymano hybrydowe kompozyty nienasyconej żywicy poliestrowej z dodatkiem mikrosfer szklanych oraz bentonitu modyfikowanego czwartorzędową solą amoniową. Zawartość bentonitu w kompozytach wynosiła 3% mas., natomiast udział mikrosfer szklanych zmieniał się w zakresie 5–15% mas. Zbadano wpływ dodatku mikrosfer szklanych na właściwości reologiczne oraz mechaniczne kompozytów nienasyconej żywicy poliestrowej zawierających modyfikowany bentonit. Stwierdzono, że optymalna zawartość mikrosfer szklanych w kompozytach poliestrowych wynosi 15% mas., kompozyty z taką zawartością mikrosfer wykazują wyraźną poprawę większości właściwości mechanicznych. Wartości modułu Younga, modułu elastyczności, naprężenia zrywającego, udarności wg Charpy'ego oraz twardości zwiększyły się o, odpowiednio, 14,7; 38,7; 17,7 oraz 25%, w porównaniu z odpowiednimi wartościami odnoszącymi się do niemodyfikowanej żywicy. Natomiast w wypadku próbki zawierającej 3% mas. bentonitu uzyskano istotne zwiększenie jedynie modułu elastyczności i udarności, wynoszące, odpowiednio, 16,5 oraz 36,0%. Kompozyty z zawartością 15% mas. mikrosfer szklanych charakteryzowały się mniejszym, o ok. 25%, naprężeniem zginającym niż żywica nienapełniona i żywica z udziałem 3% mas. bentonitu. Badania reologiczne wykazały, że wraz ze wzrostem zawartości mikrosfer szklanych w kompozycji nastąpiło zwiększenie lepkości oraz skrócenie czasu żelowania w odniesieniu do odpowiednich wartości próbki referencyjnej i próbki z 3% mas. bentonitu.

4

Study on PLA/PA11 Bio-Based Toughening Melt-Blown Nonwovens

Zhu Feichao, Yu Bin, Su Juanjuan, Han Jian

Autex Research Journal

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2020

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Vol. 20, no. 1

24--31

EN

With aim to improve the mechanical and thermal properties of poly (lactic acid) (PLA) melt-blown nonwovens (MBs), polyamide 11 (PA11) was melt blended with PLA at the weight proportions of PLA/PA11 (95/5, 90/10, 85/15, 80/20), and the corresponding PLA/PA11 MBs were also manufactured. The crystallization, thermal and rheological behaviors of PLA/PA11 blends were investigated. PLA/PA11 MBs were also characterized by morphology and mechanical properties. The results indicated that PA11, as globular dispersed phases, formed confined crystals and could improve the thermal stability of PLA matrix. The viscosity of PLA/PA11 blends was slightly increased but the rheological behaviors of “shear-thinning” kept unchanged in comparison with PLA. The average diameter of PLA/PA11 MB fibers was slightly increased, whereas the toughness of PLA/PA11 MBs including the strength and elongation were efficiently enhanced compared with those of PLA MBs.

5

Investigating the Effects of Gel Casting Parameters on the Suspension Rheology and Mechanical Properties of Titanium Carbide Green Body

Foratirad H., Baharvandi H. R., Maragheh M. G.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

581--588

EN

In this paper the chemo-rheological behavior of aqueous TiC suspension and physical properties of gelcasted green body were investigated. The monomer system used in this project was acrylamide (AM) and methylenebisacrylamide (MBAM). Polymerisation reaction was promoted by the addition of tetramethyl ethylenediamine as a catalyst and ammonium persulfate as a initiator. The effects of tetramethylammonium hydroxide (TMAH), polyethylenimine (PEI) and polyethylene glycol (PEG) dispersants on the premix solution containing TiC powder have been studied via observation of the zeta potential and rheological behavior. The optimal amount of TMAH was achieved 0.4 wt.% at pH 9. The chemorheological results showed that the gelation time decreased and viscosity increased with increasing the monomer content, solid loading, initiator amount and temperature. The highest flexural strength of gel casted green body was obtained with 50 vol% solid loading and 25 wt.% monomers content.

6

Effect of casting procedures in the structure and flow behaviour of semisolid A356 alloy

Proni C. T. W., Robert M. H., Zoqui E. J.

Archives of Materials Science and Engineering

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2015

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Vol. 73, nr 2

82--93

EN

Purpose: Evaluation of different casting methods to produce raw material for thixoforming, aiming costs reduction in the production of thixoformable alloys. Reduction of costs may stimulate the commercial use of the semisolid processing technology (SSM). Design/methodology/approach: It is analysed the effect of different casting routes in the microstructure features in semisolid A356 alloy, and in its rheological behaviour. Different casting procedures were investigated: a) pouring in water cooled Cu mould; b) same as „a)” adding electromagnetic stirring; c) same as „a)” adding mechanical vibration; d) same as „b)” with addition of grain refiner; e) same as „c)” with addition of grain refiner. Cast materials were reheated to the semisolid sate and the effect of different holding times upon the globularization of the primary phase was analysed for each cast structure. The semisolid material in each condition was evaluated concerning rheological behaviour. Mechanical properties of thixoformed products were evaluated using flexion tests. Findings: Despite the several methods currently in use to produce raw material for thixoforming, this work shows that the best combination of quality of thixoformable material/ production cost /process operationality can be achieved using casting in permanent mould, under water cooling and mechanical vibration. Resulting cast material under this condition presents grain size smaller than 100 μm, ideal for SSM. Lower the grain size, lower the primary globule size and higher the roundness of the primary phase particle and lower the apparent viscosity of the semisolid. In the best condition achieved, apparent viscosity measured was circa 105 Pa.s (similar to the working range for glass), leading to a probable homogeneous die filling during thixoforming in high pressure die casting machines (HPDC). Research limitations/implications: Regardless the best microstructure for SSM resulting from casting under mechanical vibration, it is still necessary to reach the optimum casting condition in terms of vibration in order to improve, even more, refinement of the microstructure. Practical implications: The suggested process is a simple technique to reduce costs in the production of raw material for thixoforming. The technology is easily implementable in industries. Originality/value: The development of a simple, original, low cost method to produce raw material for SSM technology.

7

Właściwości reologiczne skoncentrowanych soków owocowych przechowywanych w różnych temperaturach

Waszkiewicz-Robak B.

Postępy Techniki Przetwórstwa Spożywczego

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2003

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T. 13, nr 2

18-23

PL

Scharakteryzowano wybrane parametry określające właściwości reologiczne skoncentrowanych soków owocowych (pomarańczowego, jabłkowego i z czarnej porzeczki) przechowywanych w różnych temperaturach. Badania dokonano przy wykorzystaniu reowiskozymetru rotacyjnego Brookfield RV ///+, sprzężonego z programem komputerowym REOCALC wersja 1.0. Oznaczono lepkość, współczynnik konsystencji, granice płynięcia oraz współczynnik płynięcia skoncentrowanych soków owocowych przechowywanych w czterech temperaturach: 5,10,15 i 20 "C. Wzrost temperatury składowania skoncentrowanych soków owocowych znacznie obniżał ich lepkość, co znalazło odzwierciedlenie w obniżających się współczynnikach konsystencji oraz granicy płycięcia. Współczynniki płynięcia, określające typ płynów były charakterystyczne dla poszczególnych koncentratów i nie zmieniały się przy zmieniającej się temperaturze. Koncentraty: jabłkowy i porzeczkowy charakteryzowały się w badanych temperaturach współczynnikiem płynięcia zbliżonym do 1, natomiast skoncentrowany sok pomarańczowy charakteryzował .się współczynnikiem płynięcia wynoszącym ok, 0.5, co określa go jako płyn nieniutonowski rozrzedzany ścinaniem.

EN

Selected parameteres desribing rheological properties of concentrated fruit juices (orange, apple and blaccurrantj stored in various temeratures have been characterised. The research was conducted with the use of Brookfield viscometer RV III+, connected with REOCALC computer programme, version 1.0. Viscosity, consistency index, yield stress as well as flow behavior index of concentrated fruit juices stored in four temperatures: 5, 10, 15 and 20"C were marked. The rise of the storage temperature of concentrated fruit juices greatly reduced their viscosity, which was reflected in the consistency index as well as yield stress. Flow behavior index characterising the type of fluids turned out to be distinctive for particular concentrates and did not change in different temperatures. Apple and blackcurrant concentrations had the flow behavior index close to 1 whilst the concentrated orange juice's flow behavior index equalled about 0.5, which characterises it as a shear - thinning non-newtonian fluid.