Showing papers on "Liquid paraffin published in 2021"

The impingement of liquid boiling droplet onto a molten phase change material as a direct-contact solidification method

Abstract: The boiling of a fluid dripping on the surface of molten phase-change materials provides an efficient means for heat exchange or cooling of the melt. For the first time, in this study, the impact of acetone drops onto molten paraffin as a direct-contact solidification method is experimentally investigated to get a better insight into the interaction between the drop boiling and the heat extraction process from the phase change materials during impact. As the acetone drop impacts the molten paraffin surface, acetone starts to boil, and a portion of molten paraffin is solidified. Four impact Weber numbers (corresponding to heights of 10, 20, 30, and 40 cm) for the acetone drop and six surface temperatures for the molten paraffin (66, 68, 70, 75, 80, and 90 °C) are considered. Given the range of these two parameters, four distinct regimes of impact were observed using a high-speed camera and categorized, including the formation of the crater, crown, returned liquid paraffin column (jet), and the drop pinching off from the jet tip. Moreover, as We increased or the paraffin surface temperature decreased, the solidified paraffin’s on the molten surface grew. A correlation was obtained based on the impact Weber number and surface temperature of molten paraffin to determine the spread of solidified paraffin area on the melt free surface after drop impact. Results also showed that both the maximum crater depth and width increase with the increment of both the molten paraffin temperature and the impact Weber number.

Fabrication of single-mode circular optofluidic waveguides in fused silica using femtosecond laser microfabrication

Abstract: We demonstrate fabrication of single-mode circular optofluidic waveguides in fused silica glass substrates using femtosecond (fs) laser assisted chemical etching based on slit beam shaping. The fabrication procedure consists of four steps: slit-assisted fs laser direct writing of fused silica, selective chemical etching, polydimethylsiloxane film bonding, and vacuum-assisted liquid filling. The combination of slit beam shaping and high numerical aperture objectives ensures very narrowly modified lines with nearly circular cross-sections during laser direct writing. Introduction of a string of extra-access ports allows production of uniform circular microchannels with the diameters of ~10 µm and the lengths at the centimeter scale due to the improvement of wet chemical etching process. By vacuum-assisted filling a mixture of liquid paraffin and decane into a microchannel structure, a single-mode circular optofluidic waveguide embedded in glass can be obtained.

Liquid Paraffin Thermal Conductivity with Additives Tungsten Trioxide Nanoparticles: Synthesis and Propose a New Composed Approach of Fuzzy Logic/Artificial Neural Network

Abstract: A nanofluid (Nf), which contains tungsten trioxide, WO3, nanoparticles as solid-particles distributed in liquid paraffin, is produced. A set-up is provided to experimentally measure the thermal conductivity (TC) of this mixture at various mass fractions and temperatures. Further, two universal approximators of fuzzy logic (FL) and artificial neural network (ANN) are presented to predict the TC of this mixture. The present work’s novelty can be presented as: prepare a WO3/paraffin nanofluid, measure it's TC, and develop a novel statistical/numerical model of FL compared with ANN. As it can be seen, temperature and concentration effects positively on nanofluid TC. Moreover, ANN and fuzzy models show suitable precisions; however, the interpolation capability of the proposed fuzzy model outperforms ANN at non-trained inputs.

Performing regression-based methods on viscosity of nano-enhanced PCM - Using ANN and RSM

Abstract: Evaluation of the use of linear and nonlinear regression-based methods in estimating the viscosity of MWCNT/liquid paraffin nanofluid was investigated in this study. At temperature range of 5–65 °C, the viscosity of samples containing MWCNT nanoparticles at 0.005–5 wt.% which is measured by a Brookfield apparatus, was first evaluated to determine the response to the shear rate. The decrease in viscosity due to the increase in shear rate indicated that the rheological behavior of the nanofluid was non-Newtonian and therefore, in addition to temperature and mass fraction, the shear rate should be considered as an effective input parameter. Linear regression was performed by response surface methodology (RSM) and it was observed that the R-square for the best polynomial was 0.988. The results of nonlinear regression also showed that the neural network consisting of 3 and 13 neurons in the input and hidden layers was able to estimate the viscosity of the nanofluid more accurately so that the R-square value was calculated to be 0.998.

Pyromellitic-Based Low Molecular Weight Gelators and Computational Studies of Intermolecular Interactions: A Potential Additive for Lubricant.

Abstract: Low molecular weight gelators (LMWG) have been extensively explored in many research fields due to their unique reversible gel-sol transformation. Intermolecular interactions between LMWG are known as the main driving force for self-assembly. During this self-assembly process, individually analyzing the contribution difference between various intermolecular interactions is crucial to understand the gel properties. Herein, we report 2,5-bis(hexadecylcarbamoyl)terephthalic acid (BHTA) as a LMWG, which could efficiently form a stable organogel with n-hexadecane, diesel, liquid paraffin, and base lubricant oil at a relatively low concentration. To investigate the contribution difference of intermolecular interactions, we first finished FT-IR spectroscopy and XRD experiments. On the basis of the d-spacing, a crude simulation model was built and then subjected to molecular dynamics (MD) simulations. Then, we knocked out the energy contribution of the H-bonding interactions and π-π stacking, respectively, to evaluate the intermolecular interactions significantly influencing the stability of the gel system. MD simulations results suggest that the self-assembly of the aggregates was mainly driven by dense H-bonding interactions between carbonyl acid and amide moieties of BHTA, which is consistent with FT-IR data. Moreover, wave function analysis at a quantum level suggested these electrostatic interactions located in the middle of the BHTA molecule were surrounded by strong dispersion attraction originating from a hydrophobic environment. Furthermore, we also confirmed that 2 wt % BHTA was able to form gel lubricant with 150BS. The coefficient of friction (COF) data show that the gel lubricant has a better tribological performance than 150BS base lubricant oil. Finally, XPS was performed and offered valuable information about the lubrication mechanism during the friction.

Si3N4 nanofelts/paraffin composites as novel thermal energy storage architecture

Abstract: The environmental problems associated with global warming are urging the development of novel systems to manage and reduce the energy consumption. An attractive route to improve the energy efficiency of civil buildings is to store the thermal energy thanks, during heating, to the phase transition of a phase-change material (as paraffin) from the solid to the liquid state and vice versa. The stored energy can be then released under cooling. Herein, we developed a novel material (nanofelt) constituted by Si3N4 nanobelts able to absorb huge amounts of liquid paraffin in the molten state and to act as an efficient shape stabilizer. The nanofelt manufacturing technology is very simple and easy to be scaled-up. The effect of the Si3N4 nanofelts density and microstructure on the paraffin sorption and leakage and on the thermal properties of the resulting composite structures is investigated. It is shown that the produced Si3N4/paraffin composites are able to retain enormous fractions of paraffin (up to 70 wt%) after 44 day of desorption test on absorbent paper towel. The thermal energy storage efficiency measured through calorimetric tests is as high as 77.4% in heating and 80.1% in cooling.

Pickering emulsions stabilized by partially acetylated cellulose nanocrystals for oral administration: oils effect and in vivo toxicity

Abstract: Pickering emulsions assembled from biopolymer nanoelements are promising as forms of oral delivery systems. In this study, rod-like partially acetylated cellulose nanocrystals (CNCAc) were used for the preparation of oil-in-water Pickering emulsions using decane (model), olive and liquid paraffin oils. It is concluded that 0.5–1.0 wt% of particles are enough to stabilize emulsions in the presence of CNCAc. Stable emulsions with microdroplets ranging from less than 1 to 5 μm were prepared. The general trend for the studied emulsions is an increase in dynamic viscosity with increasing NaCl concentration. It has been shown (potentiometric titration in conjunction with 2 pK-modeling) that active centers on the surface of CNCAc particles creating an oil/water interface decreased, and cation sorption/desorption processes were hindered as compared to original particles in sol. A decrease in the lifespan of males and females of Drosophila melanogaster was observed when CNCAc and emulsions were introduced into the nutrient medium. CNCAc hydrosol had a negative effect on the permeability of Drosophila’s intestinal barrier in males. However, CNCAc-stabilised o/w emulsions with olive or liquid paraffin oil had a positive effect on the permeability of intestinal barrier in Drosophila’s females. No toxic effects were observed in mice when orally administered. The results obtained in the acute toxicity study suggests that acute administration of CNCAc and emulsions did not produce death in 50% of mice at the dose of 2000 mg/kg, internal organs were unchanged.

Curcumin-containing Silver Nanoparticles Prevent Carbon Tetrachloride- induced Hepatotoxicity in Mice.

Abstract: Background Hepatotoxicity remains an important clinical challenge. Hepatotoxicity observed in response to toxins and hazardous chemicals may be alleviated by delivery of the curcumin in silver nanoparticles (AgNPs-curcumin). In this study, we examined the impact of AgNPs-curcumin in a mouse model of carbon tetrachloride (CCl4)-induced hepatic injury. Methods Male C57BL/6 mice were divided into three groups (n=8 per group). Mice in group 1 were treated with vehicle control alone, while mice in Group 2 received a single intraperitoneal injection of 1 ml/kg CCl4 in liquid paraffin (1:1 v/v). Mice in group 3 were treated with 2.5 mg/kg AgNPs-curcumin twice per week for three weeks after the CCl4 challenge. Results Administration of CCL4 resulted in oxidative dysregulation, including significant reductions in reduced glutathione and concomitant elevations in the level of malondialdehyde (MDA). CCL4 challenge also resulted in elevated levels of serum aspartate transaminase (AST) and alanine transaminase (ALT); these findings were associated with the destruction of hepatic tissues. Treatment with AgNPs-curcumin prevented oxidative imbalance, hepatic dysfunction, and tissue destruction. A comet assay revealed that CCl4 challenge resulted in significant DNA damage as documented by a 70% increase in nuclear DNA tail-length; treatment with AgNPs-curcumin inhibited the CCL4-mediated increase in nuclear DNA tail-length by 34%. Conclusion Administration of AgNPs-curcumin resulted in significant antioxidant activity in vivo. This agent has the potential to prevent the hepatic tissue destruction and DNA damage that results from direct exposure to CCL4.

Production of Gaseous Olefins from Syngas over a Cobalt-HZSM-5 Catalyst

Abstract: Light olefins (C2–C5) are high-value platform chemicals used to produce plastics, lubricants, coating material, and surfactants, and can be intermediates to produce transportation fuels. In this study we report on the development of a Co-based catalyst for direct conversion of fossil as well as biomass derived syngas into light olefins that enables high conversion and olefin/paraffin (O/P) product ratio, minimal selectivity to CO2 (< 1%) and wax formation (C14+ selectivity < 1%). Over a Co/HZSM-5 bi-functional catalyst 38% CO conversion with C2–C5 olefin selectivity of 48%, and O/P ratio of 4.0 was achieved at 240 °C, 17 bar, and 1.5 L/(g–h). In addition to a gaseous olefin-rich stream a C6–C13 mixed olefin/paraffin liquid byproduct was also produced with 25% selectivity. Both Co loading and the HZSM-5 acidity levels were optimized to maintain the balance between the hydrogenation and the cracking activity to generate high levels of C2–C4 olefins. A suite of catalyst characterization tools were used to correlate the physical and chemical property of the catalyst to the performance of the catalyst towards syngas conversion and C2–C4 olefin selectivity. Direct conversion of syngas into specialty chemicals (light/gaseous olefins) as well as liquid hydrocarbons over cobalt-HZSM-5 catalysts.

Tribological performances of hexagonal boron nitride nanosheets via surface modification with silane coupling agent

Abstract: Hexagonal boron nitride (h-BN) is a promising lubricant additive for decreasing wear and friction. However, the poor dispersion stability and bulky size of h-BN restricted its lubrication application. In this paper, bulk h-BN was exfoliated into h-BN nanosheets (h-BNNSs), and then the self-made h-BNNSs were chemically modified with silane coupling agent via a facile and scalable reaction method. The morphology and structure of surface-functionalized h-BNNSs (m-BNNSs) were certified using a series of characterizations. Results revealed that h-BNNSs could be chemically well capped by surface modifier and the lipophilic groups were covalently attached to h-BNNSs surfaces. The m-BNNSs composite possessed long-term dispersion in liquid paraffin (LP). At the optimal adding content of 0.6 wt%, coefficient of friction and wear volume of m-BNNSs composite were decreased by about 31.9% and 53.8% compared with those of LP, respectively. Therefore, m-BNNSs composite as a lubricating oil additive has high research value and good prospects of lubrication applications.

Thermodynamic properties of cotton dyeing with indigo dyes in non-aqueous media of liquid paraffin and D5:

Abstract: On the basis of investigation into the dyeing equilibrium of cotton fibers with indigo dyes in decamethylcyclopentasiloxane (D5), liquid paraffin and water, the thermodynamic properties of cotton d...

Formulasi dan Evaluasi Lotion Ekstrak Alpukat (Persea Americana) sebagai Pelembab Kulit

Abstract: Avocado (Persea a mericana) contains a lot of vitamin A, vitamin B , vitamin C and vitamin E which is good to be used in skin care. One of the cosmetics for skincare is lotion, which is a liquid emulsion consisting of oil p hase and water phase stabilized by emulgator . Lotion is used to protect and maintain skin moisture level . The purpose of t his research was to formulate and evaluate the lotion in order to assure the physical characteristic and stability were accepted accord ing to the Handbook of Pharmaceutical Excipients and Indonesia Pharmacopeia requirements . Formulation were made by using the se following ingredients : g lyceryl monostearat e , cera alba, tween 80, glycerin, liquid paraffin, benzyl alcohol, perfume, aquadest. The study used 2 variation of concentration, which is 0.5% and 1% avocado extract as active substance , besides there is variations in g lyceryl m onostearat e (5.5% and 5.7%), c era alba (2.7% and 2.9%), t ween 80 (3.5% and 3.7%), g lycerin (10% and 12%), liquid paraffin (10% and 12%), and benzyl alcohol (0.15% and 0.17%) in formulations I and II. Lotion was then tested for its physical properties, which include organoleptic test, homogeneity test, pH test, and spread ability test , lastly hedonic and irritation test were also being examined. Based on the results of physical properties test, both lotion formulations showed a viscous texture, beige and dark beige colo r with a distinctive odor, homogeneous, not irritating, hav e a pH value in the range of 4.55-5.31 with 4.9-5.15 cm spread . In the hedonic test on 10 panelists, lotion I formulation gave the most satisfaction score and comfort y fr om respondents. Respondent's satisfaction on the appearance comprise the texture, color, and odor. Besides, viscosity and s pread ability were also marked as how comfort the lotion is when it was a pplied to the respondent’s skin. Keywords : Avocado, Extract, Lotion, Cosmetic, Moisturizer

Dielectric Spectroscopy of Fluids and Polymers for Microwave Microfluidic Circuits and Antennas

Abstract: The permittivity response from 0.5 to 40 GHz of ethyl acetate (C4H8O2), ethylene glycol (CH2OH)2, castor oil (C57H104O9), liquid paraffin, and other fluids commonly used for microwave microfluidic antennas and circuits is reported. The response of selected polymer solids, such as polydimethylsiloxane (PDMS), acrylonitrile butadiene styrene (ABS), acrylic, nylon, and others, used in microfluidics and 3-D printing of microwave structures was also studied from 0.5 to 20 GHz. Permittivity measurements were taken with a coaxial probe. Using a nonlinear least-squares fitting routine, the Cole–Cole dielectric relaxation model parameters are found for each material under test, thereby providing an analytic expression for their permittivity response.

The Influence of Additives on the Rheological and Sedimentary Properties of Magnetorheological Fluid

Abstract: In this research, the influence of surfactant on the rheological and sedimentary properties of the magnetorheological fluid (MRF) was tested and analyzed. The surfactants were stearic acid, sodium dodecyl sulfate (SDS), and their mixture, respectively. The MRF was composed of carbonyl iron particle, liquid paraffin, silicone oil, graphite particle, bentonite, stearic acid, and SDS. The experimental results indicated that the rheological properties of the MRF were mainly influenced by the mass fraction of carbonyl iron particle. When the mass fraction of carbonyl iron particle and surfactant was the same, the shear stress of MRF with stearic acid was larger than that of MRF with SDS, and the maximum increment was 73.81%. When the mass fraction of carbonyl iron particle was 40%-50%, the shear stress of MRF increased firstly and then decreased with the increasing of the external magnetic flux density. When the mass fraction of carbonyl iron particle was 60%-70%, the shear stress of MRF firstly increased and then kept stable with the increasing of the external magnetic flux density. The results indicated that the sedimentary property of MRF with the mixture was better than that of MRF with stearic acid or SDS. The settling rate of MRF with the mixture increased 91.53% when compared with samples with other additives.