Kinetic Viscosity Research Articles

Green energy using oscillatory baffled reactors: advances in biodiesel production from high free fatty acid karanja oil

Abstract The global demand for sustainable and ecologically friendly energy sources has spurred biodiesel research. Civilization, urbanization, and population growth have drastically boosted transportation energy consumption. Energy demand is causing fossil fuel crises. Replace petroleum diesel to solve energy and environmental problems. Biofuels have very vast scope in the area of energy sector. Karanja oil, derived from the seeds of the Karanja tree (Pongamia pinnata), is a promising biodiesel feedstock due to its high Free Fatty Acid content. This study uses Oscillatory Baffled Reactor (OBR) to produce biodiesel from Karanja oil. The feedstock is high-FFA Karanja oil trans-esterified in two steps. In OBR, reaction time is only 15 min, whereas in conventional reactor it takes 1–2 h to produce biodiesel. Optimizing biodiesel synthesis involved varying H2SO4 concentrations from 1 vol% to 5 vol% and 0.3 to1.0 wt% of NaOH concentration for first and second step respectively. Oil-to-alcohol molar ratios 1:6, 1:9 and 1:12. Optimization occurs at 1:12 oil-to-alcohol ratio, 1 vol% H2SO4 catalyst, and 0.6 wt% NaOH catalyst. Studies have also examined how catalyst concentration and oil: alcohol molar ratio affect biodiesel conversion and physical qualities such kinetic viscosity, specific gravity, and acid value. This study shows that OBR can increase biodiesel production from high-FFA Karanja oil, which further opens up opportunities for additional study and improvement.

Interactions between polymer molecules and hydrodynamic responses in multi-ion induced charge electroosmosis

Induced charge electroosmosis (ICEO) can assist lab-on-a-chip devices and macromolecular separation involving interface, multi-ion species, and solution properties. To supplement the mechanistic insights into the ICEO phenomenon in complex electrochemical scenarios, we numerically address electrokinetic ion transport–fluid flow coupling regulated by multi-ion species and polymer macromolecular rheology around a polarized cylinder. The physics of the ICEO are analysed from multiple perspectives, including the azimuthal velocity, flow type, energy distribution, interfacial ion transport, and electroelastic instability. The main findings are as follows: (1) Deviations under neutral pH conditions (multi-ion species) cause flow field asymmetry and alter the input energy distribution (PE) in the tight double layer. Polymers greatly modify the interfacial force features in ion-enriched regions, as identified by the first stress difference (N1). (2) The kinetic energy vs. viscosity ratio (β) represents the nonlinear enhancement curve Ek=0.011*exp(β/0.64)-0.0138 due to the weakened effective viscosity Rvis. In addition, shear thinning notably lifts the charge density and salt concentration at the cylinder surface, which boosts the PE. (3) Quadrupolar vortex modes impact the positive correlation between β and the ion current (Jtotal) at different pH levels, resulting in less ion current dependence for small β. A low enhancement efficiency occurs at 10-4 ≤ α (molecular anisotropy) ≤ 0.1, whereas a high efficiency exists at α > 0.1. Electroelastic instabilities are confirmed by the spatiotemporal evolution of the velocity fluctuation, with a broadband structural power-law decline in the power spectral density. These results allow microdevice mixing manipulation and disclose non-Newtonian barrier of electrokinetic dynamics.

Nanofluid heat transfer enhancement in microchannels: Investigating phases interactions using multiphase Eulerian model

This study employs a robust multiphase Eulerian model to mimic heat transfer enhancement using nanofluids in a circular microchannel. Unlike the Eulerian models reported in the literature, the current model incorporates phase interactions, and its accuracy is significantly improved by integrating collision viscosity, kinetic viscosity, and frictional viscosity. Comparative analysis against other models like mixture and discrete phase models demonstrates superior performance of the current model, particularly for solid particle volume fractions exceeding 1 %. The model evaluates water-based nanofluids (Ag NPs, MgO, ZnO, Al2O3, ZrO2, SiO2) in circular microchannels. Ag NPs/water excels at low volume fractions and high Reynolds numbers, while MgO/water performs better at higher volume fractions. Moreover, the analysis of the Euler number indicates a decreasing trend with increasing Reynolds number across all nanofluids. However, no notable variation in the Euler number is observed when maintaining constant volume fraction and Reynolds number. Ultimately, the model is applied to obtain bulk fluid properties, such as viscosity and thermal conductivity, after suspending the nanoparticles. Subsequently, these properties were incorporated into the single-phase model. Utilizing these derived bulk properties was found to substantially enhance the accuracy of the single-phase model, demonstrating its reliability by yielding results within 13.52 % of experimental data.

Degradative Quality and Emission Implications of Repeatedly Heated Cooking Oil in Indoor Environment

The study examined the effects of heating the same batch of oil for multiple frying cycles on the pollutants that are released into the air and the degradation of the oil’s quality. Principal component analysis under the physicochemical metrics framework was used to study singular and interaction effects of three oil brands, frying duration and temperature. Physicochemical parameters showed that peanut oil has high unsaponifiable matters, the refractive index and kinetic viscosity prior to frying. Specific gravity and acid value were significantly lower for soya bean oil after frying with values 0.42 ± 0.02 and 0.20 ± 0.01 in order. The values of 4.09 ± 0.04 meqO2/kg and 114.96 ± 0.23 mgKOH/g obtained for peroxide value and saponification value respectively were significant for olive oil during post frying analysis. The emission values were in the ranges 98.17 ± 0.15 (x103)-573.20 ± 0.20 (x103),11.0 mg/m3 at 60 °C-34.0 mg/m3 at 140 °C, 0.051 mg/m3 at 60 °C-0.088 mg/m3 release at 140 °C, 59.0 μg/m3 at 80 °C-72.0 μg/m3 at 120 °C, and 0.057 mg/m3 at 60 °C-0.078 mg/m3 at 140 °C respectively for PAH, CO, NO2, SPM, SO2. Temperature had a significant impact on the rates of emissions when combined with time. The inherent patterns and trends within the data matrix suggest that oil brand quality was the most significant factor influencing the clustering of observations. Therefore, heating cooking oils to moderate temperatures and using a large volume of the oil could result in minimal rates of evaporation and pollutants emission

Physio-Chemical Properties and Anti-Microbial Activities of Date Seed Oil’s in Saudi Arabia

The preparation of soap from extracted date seed oil along with anti-microbial activities, Gas Chromatography-Mass Spectrometry (GC-MS), and physio-chemical properties comprise the areas examined by the methodology implemented in this research. Ascertaining the fatty acid content in such date seed oil embodies the research objective of this investigation. Color Criteria should be within the range of 2.8 to 13.5 (red-yellow),acid value 1.42 Mg KOH/g oil, flash point 245C˚, a refractive index of 1.468, a Kinetic viscosity of 20cp, and a density of 0.9188g cm-3 comprised the physical assessment of the date oil. On the other hand, a peroxide value of 7.4 mg of peroxide/kg oil, a saponification value of 0.279 mg g-1, an acid value of 2.67, and an iodine value of 74.31 gm I2/100 gm fat comprised the chemical assessment. GC-MS was utilized to ascertain the quantity of fatty acid content in the date seed oil. Oleic acid (Omega-9) and Linoleic acid (Omega-6) comprised the unsaturated fatty acid content in such oils producing values of 38.25% and 2.33% respectively, where the percentage represents the total fatty acid components. Palmitic acid and lauric acid encapsulated the saturated fatty acid content producing values of 0.42% and 35.76%, respectively. The elemental constituents found in the date oil include calcium (29 ppm), magnesium (0.359 ppm), iron (1.27 ppm), and sodium (70 ppm). The date seed oil shown demonstrated anti-bacterial activity high effect 30mm against Escherichia coli (Gram negative) and moderated effect 20mm against Staphylococcus aureus, (Gram positive) respectively compared to standard drug, Cephradine. Which may be due to bioactive compounds including plant-derived phenolic molecules (589mg/100g). In this way, the date seed oil had moderate inhibitory effect 40mm against Candida albicansa and low inhibitory effect 20mm against Aspergillus flavus. which may be increases with the increase of the compound concentration compared with standard antifungal agent Nizoarm. While the date oil extract showed good properties in soap in terms of viscosity, Hardness, color and moderate solubility.

Boundary layer transition due to distributed roughness: effect of roughness spacing

The influence of roughness spacing on boundary layer transition over distributed roughness elements is studied using direct numerical simulation and global stability analysis, and compared with isolated roughness elements at the same Reynolds number $Re_h=U_eh/\nu$ ( $U_e$ is the boundary layer edge velocity, h is roughness height and $\nu$ is the kinetic viscosity of the fluid). Small spanwise spacing ( $\lambda _z=2.5h$ ) inhibits the formation of counter-rotating vortex pairs (CVP) and, as a result, hairpin vortices are not generated and the downstream shear layer is steady. For $\lambda _z=5h$ , the CVP and hairpin vortices are induced by the first row of roughness, perturbing the downstream shear layer and causing transition. The temporal periodicity of the primary hairpin vortices appears to be independent of the streamwise spacing. Distributed roughness leads to a lower critical roughness Reynolds number for instability to occur and a more significant breakdown of the boundary layer compared with isolated roughness. When the streamwise spacing is $\lambda _x=5h$ , the high-momentum fluid barely moves downward into the cavities and the wake flow has little impact on the following roughness elements. The leading unstable varicose mode is associated with the central low-speed streaks along the aligned roughness elements, and its frequency is close to the shedding frequency of hairpin vortices in the isolated case. For larger streamwise spacing ( $\lambda _x=10h$ ), two distinct modes are obtained from global stability analysis. The first mode shows varicose symmetry, corresponding to the primary hairpin vortex shedding induced by the first-row roughness. The high-speed streaks formed in the longitudinal grooves are also found to be unstable and interact with the varicose mode. The second mode is a sinuous mode with lower frequency, induced as the wake flow of the first-row roughness runs into the second row. It extracts most energy from the spanwise shear between the high- and low-speed streaks.

Process optimization for blended waste frying oil in biodiesel production using CaO derived from African periwinkle shell catalyst through response surface methodology

Biodiesel is one of the renewable energy alternatives for fossil fuel because of its biodegradability, no toxicity, and environmentally friendly nature. Investigations have been made on transesterifying blended waste frying oil (BWFO) into biodiesel using African periwinkle shells (APS) heterogeneous catalyst. The BWFO, a mixture of 60:40 groundnut oil and waste palm oil, usually causes serious environmental problems when indiscriminately disposed. After being calcined, the non-activated APS (RAPS) was further sulphonated to create an acid-activated APS (AAPSA) catalyst. Scanning electron microscopy (SEM), X-ray fluorescence (XRF), the Brunauer-Emmett-Teller method (BET), and other techniques were used to characterize the produced RAPS and AAPSA. Gas chromatography-mass spectrometry (GC-MS) and Fourier-Transform Infrared Spectroscopy (FTIR) were used to evaluate the produced biodiesel. Besides, a series of physiochemical properties including acid value, density, kinetic viscosity, flash point, cloud point, pour point, and other fuel properties of produced BWFO, were evaluated using ASTM standard methods. The central composite design (CCD) of the response surface methodology (RSM) was utilized for modeling and process optimization of biodiesel production from BWFO.The characterization results revealed that CaO (62.07 %) is the main constituent of AAPSA. The RPSA's pore volume and BET surface area were 0.34 cm3/g and 68.93 m2/g, respectively. BET surface area (30.9%) and pore volume (48.2 %) increased for the AAPSA. The significant increase in surface area and pore volume of AAPSA indicates an enhanced number of acid sites and catalytic activity of the acid-modified catalyst towards higher produced biodiesel yield. The optimal conditions for the reaction temperature, reaction time, catalyst loading, and methanol to oil ratio (mtOH/oil) were 55 °C, 142.5 min, 2.5 wt%, and 14.25:1. This resulted in the maximum yield of biodiesel, which was 91.5 %. Moreover, the AAPSA catalyst performed excellently, and the resulting biodiesel fuel's properties are comparable with those of ASTM D6751 and EN 14214 standards. Hence, AAPSA is a potential solid acid bifunctional heterogeneous catalyst to produce biodiesel from BWFO. Therefore, this study's novelty comprises the synthesis of solid acid bifunctional heterogeneous catalyst from giant African land snail shells and the optimization of the process variables involved in the production of biodiesel from BWFO.

Effect of oxygen concentration on the velocity in buoyant turbulent diffusion flames

To better understand fire dynamics of buoyant turbulent diffusion flames under different oxygen concentrations (OCs, volumetric basis), we have recently conducted measurements on the flame temperature, radiation, and soot temperature and volume fraction under normal and reduced OCs. In the present study, particle image velocimetry (PIV) technique was employed to investigate the effect of OC (20.9%, 16.8%, and 15.2%) on the velocity field of the same flames with a theoretical heat release rate (HRR) of 15 kW. The statistics of the velocity field, such as mean and standard deviation of velocity, turbulent kinetic energy, Reynolds stress, and turbulent viscosity, were investigated and compared among different OCs. Results show that OC has minimal effect on the velocity distribution at heights close to the flame length. However, at lower heights above burner (HABs), turbulent mixing is reduced under reduced OCs, and the velocity shows an increased value at the flame centerline but with a narrower profile along the radial direction. Finally, a comparison with previous data was conducted and analyzed to further explore the fire dynamics. This study improves the physical understanding of related fire dynamics under reduced OCs and provides a comprehensive dataset for turbulent fire modeling validation.

Biodiesel production from Sisymbrium irio as a potential novel biomass waste feedstock using homemade titania catalyst

Biomass waste streams are a possible feedstock for a range of eco-friendly products and a crucial alternative energy source for achieving carbon neutrality; therefore, the efficient management of biomass waste has taken on a greater significance in recent years. Due to its well-comparable physic-chemical properties with fossil diesel, biodiesel is a potential substitute for fossil fuel. This study aimed to synthesize biodiesel from the widely available non-edible seed oil of Sisymbrium irio L. (a member of the Brassicaceae family) via a transesterification procedure over a homemade TiO2 catalyst. At 1:16 oil to methanol ratio, 93% biodiesel yield was obtained over 20 mg catalyst at 60 °C and 60 min. The ASTM methods were used to analyze the fuel properties. The quantitative and qualitative analysis was performed by FT-IR, GC-MS, and NMR spectroscopy. GC-MS study confirms 16 different types of fatty acids of methyl esters. FT-IR analysis showed important peaks that confirm the successful occurrence of biodiesel. 1H-NMR and 13C-NMR showed important peaks for converting triglycerides into corresponding FAMEs. The acid value (0.42 mg KOH/mg/kg), flash point (106 °C), and water content (0.034) of biodiesel are below the specified limit of ASTM D6751 whereas kinetic viscosity (3.72 mm2/s), density (0.874 kg/L), cloud point (− 4.3 °C) and pour point (− 9.6 °C) and high heating value (41.62 MJ/kg) fall within the specified range of ASTM D6751 test limit. The Unsaturation degree and oxidative stability of biodiesel are above ASTM D6751 test limit. The physic-chemical properties of the SIB confirm that it is eco-friendly fuel and a competitive source for manufacturing biodiesel on a commercial scale. Furthermore, the SIB is engine friendly and has good fuel efficacy.

Synthesis And Characterization Of Epoxidized Thevetia Peruviana Seed Oil

The seed oil of Thevetia peruviana was extracted using soxhlet extraction method with n-hexane. The physicochemical parameters of the extracted oil were determined using standard analytical methods. The extracted oil was epoxidized using peracid generated in situ from aqueous hydrogen peroxide (H2O2) and glacial acetic acid. The epoxidized oil was analysed for the functional groups present using Fourier Transform Infrared (FTIR) Spectrometer. The physiochemical parameters of Thevetia peruviana seed oil showed the following results; acid value (3.86 mg KOH/g), iodine value (92.5 Wij’s), peroxide value (30.0 meq/kg), kinetic viscosity (1.7cp) and saponification value (121.76 mgKOH/g) while the epoxidized oil has acid value (0.49 mg KOH/g), iodine value (68.10 Wij’s), peroxide value (7.99 meq/kg), kinetic viscosity (5.57cp) and saponification value (156.1 mgKOH/g). The FTIR results showed that both unepoxidised and epoxidized oils showed the following functional groups OH at wavelengths 3469.50 cm-1, 3468.72 cm-1 and 3467.75 cm-1; CH at 2917.75 cm-1, 2922.47 cm-1 and 2924.61 cm-1; CH2 at 2852.39 cm-1, 2852.81 cm-1 and 2853.68 cm-1; C=O at 2679.32 cm-1, 2679.41 cm-1 and 2673.30 cm-1; C=C at 1656.14 cm-1, 1654.55 cm-1 and 1655.5 cm-1 while the C≡C at wavelength 2030.69 cm-1 that was identified in the unepoxidised oil was found to be absent in the epoxidised oil and a peak indicating epoxyl group was identified in the epoxidized oil. The percentage conversion of oxirane was determined to be 83.5%. This shows that epoxides were effectively formed. The high oil yield and percentage conversion of oxirane makes Thevetia peruviana a good feedstock for production of industrial intermediates

Remarkable relation between melting entropy and kinetic viscosity in metallic glasses

There has been so far no consensus regarding the roles of melting entropy on glass formation. For this purpose, a study has been conducted on three compositions of the pseudo-binary alloys, Zr2Ni-Ti2Ni, viz., the eutectic compositions (Zr2Ni)0.206(Ti2Ni)0.794, (Zr2Ni)0.654(Ti2Ni)0.346, and the Laves compound (Zr2Ni)0.44(Ti2Ni)0.56. The study results of melting entropies, melting viscosities, and glass formabilities of the alloys unequivocally shows the fact that low melting entropy and high melting viscosity facilitate glass formation. From the data of different classes of systems, a unique relationship between melting entropy and melting viscosity has arisen in glass forming systems, which highlights the positive roles of low melting entropy on glass formation from a special perspective. This study of thermodynamics, kinetics, and glass formation highly suggests the melting entropy should be taken as a crucial reference for designing metallic glasses.

Impact of starch-hydrocolloid interaction on pasting properties and enzymatic hydrolysis

Hydrocolloids are extensively used for food processing because their techno functional properties (emulsifier, stabilizer, and structural agent). But there is increasing interest in their role connected with nutritional improvements, particularly related to starch hydrolysis rates, which might involve the viscosity resulting from starch-hydrocolloid interaction. The objective of this research was to investigate the impact of gels viscosity on the enzymatic hydrolysis of a range of starch gels made with different starches and hydrocolloids. Heterogeneous systems (starch-hydrocolloid) were prepared with several starches (corn, wheat, rice, potato, cassava, pea) and hydrocolloids (locust bean gum, guar gum, xanthan gum, hydroxypropylmethylcellulose K4M, psyllium) at different concentrations (0%–0.5% - 2.5%). The starch-hydrocolloid pasting behavior and their susceptibility to amylase hydrolysis was recorded with the Rapid Viscoanalyzer following a rapid method (Santamaria, Montes, Garzon, Moreira, & Rosell, 2022a). The viscosity decay due to alpha-amylase activity was modeled to obtain starch gels hydrolysis rate (k). A negative correlation was found among kinetic constant (k) and viscosity at 37 °C (r = −0.55), setback (r = −0.50), and area under the pasting curve (r = −0.42). For instance, xanthan gum and psyllium addition showed strong negative correlation between kinetic constant and viscosity at 37 °C (r = −0.75) and setback (r = −0.79), respectively, particularly when blended with potato starch. These correlations indicate that pasting properties of the starch-hydrocolloid systems might be predictors of the enzymatic digestion rate of the gels, allowing the design of foods with controlled postprandial glucose response.

Phase field theory for pressure-dependent strength in brittle solids with dissipative kinetics

A phase field theory of fracture mechanics is formulated to address dependence of material strength on stress state, noting that brittle solids are usually more fracture resistant when mean stress is compressive. Fracture is addressed via a dissipative kinetic law which instills rate dependence and viscous resistance to propagation. A dependence of kinetic viscosity on triaxiality for locally compressive stress states is proposed. Solutions are derived to one-dimensional problems for an isotropic material, linear or nonlinear elastic, under different loading protocols: uniaxial stress extension, uniaxial stress compression, and uniaxial strain compression. Analytical results enable determination of parameters and verification of finite element predictions. Three-dimensional simulations of polycrystalline microstructures are enacted under similar loading protocols. Results provide insight into effects of crystalline microstructure and anisotropy for different stress states. With increasing confinement, the ratio of macroscopic pressure to shear stress increases, and influences of microstructure and anisotropy on average stress and ductility are reduced.

On rate dependence and anisotropy in phase field modeling of polycrystalline fracture

A phase field theory of fracture incorporating rate dependence (i.e., kinetic viscosity) and anisotropic elasticity is implemented to study strength and failure modes in polycrystalline materials. After presentation of the constitutive framework, a new analytical solution is derived for one-dimensional (1D) homogeneous loading at constant strain rate, wherein crack viscosity is enabled. The three-dimensional (3D) theory is implemented in a finite element (FE) context, with static and dynamic solutions verified up to peak loading for homogeneous microstructures. Extensive simulations of heterogeneous polycrystalline microstructures follow, where baseline material properties correspond to either boron carbide (B4C) or titanium diboride (TiB2). Results quantify effects of loading rate, elastic anisotropy, cleavage energy anisotropy, and grain boundary surface energy on tensile strength. Notable are effects of strong basal texture, which influences average strength via both elastic anisotropy and basal cleavage plane orientation. Effects of loading rate are naturally more prominent for materials that fail mostly intergranularly rather than transgranularly, in agreement with experimental observations.

Non-invasive evaluation of blood flow through a healthy and stenosed coronary artery

The current numerical analysis was utilised to compare the hemodynamic effects caused by flow disruptions in coronary arteries with and without stenosis in order to evaluate the hemodynamic importance of patient-specific coronary stenosis using Computational Fluid Dynamics (CFD) to provide information to the public, particularly surgeons, and assist them in reducing the risk of stenosis. Assuming the flow is turbulent and non-Newtonian viscosity, the Carreau model is incorporated by utilizing STAR-CCM+ 2021.2.1. The test model is a patient-specific coronary stenosis with area stenosis (60%). The velocity, shear stress, and strain rate were evaluated and revealed that the stenosed artery experiences more hemodynamic impacts as the flow rate increases compared to the normal artery. The turbulent kinetic energy and turbulent viscosity ratio findings showed that the TKE and TVR are almost the same downstream of the stenoses, with the TKE and TVR being somewhat higher with the stenosed artery model than the unstenosed artery model, and it increases as the flow increases. Moreover, to determine the stenosis severity, the coefficient of pressure drop (CDP) and lesion flow coefficient (LFC) were used and showed that the CDP value be higher in stenosed artery (107pa) compared to a normal artery (5.2pa) but it was less when the flow increased (84.4pa), (2.5pa) respectively. whereas the LFC value in the stenoses artery is higher (0.61) and rises as flow increases (0.69).

Characteristics, mechanisms, and environmental LCA of WMA containing sasobit: An analysis perspective combing viscosity-temperature regression and interface bonding strength

Warm mix asphalt (WMA) with organic additive technology has been highly recommended in asphalt pavement. However, the viscosity-reduction mechanism, viscosity-temperature relationship, and field application effects have yet to be well excavated. Therefore, the characteristics, mechanisms, and environmental benefits of WMA containing sasobit warm agent (SWA) were developed. Kinetic viscosity, Brookfield viscosity, modified BBS tests, and rheological property tests were performed. The results showed that WMA with SWA significantly lowered the mixing and compaction temperatures. They were reduced by 38.9 °C and 36.8 °C using 4% SWA, respectively, compared with 70# base asphalt. The bonding strength between WMA and asphalt or aggregate was also improved after adding SWA. Based on the balanced performance design, the optimum SWA dosage was 3%. Measured field data showed that the asphalt fume, BSO, and benzopyrene reductions were more than 80% in WMA pavement construction adding 3% SWA. Moreover, energy consumption and carbon emissions in the LCA of WMA pavement construction adding 4% SWA were reduced by 134.86 MJ/t (21.56%) and 112.03 kg/t (40.60%), respectively. Overall, the characteristic, mechanism, and LCA analysis of WMA with SWA confirmed its great potential and application prospects.

Some Methods for Determining the Viscosity Index of Hydraulic Oil

Objectives: To determine the viscosity index of hydraulic oil by three methods. These methods are: the viscosity index determined by a mathematical relationship, using a calculation program and the graphic method. The study also intends to determine the viscosity-temperature coefficient for the hydraulic oil. Methods: To determine the kinematic viscosity of the hydraulic oil, we used a calculation formula that transforms the dynamic viscosity into kinetic viscosity knowing the density of the fluid. Thus, we determined the dynamic viscosity of the hydraulic oil with the Schott Ubbelohde viscometer at the temperatures of 40 and 100◦C. To determine the dynamic viscosity of hydraulic oil at 40◦C and 100◦C, we used a water bath. The dynamic viscosity thus obtained was transformed into the kinematic viscosity of the oil by dividing it by density. Findings: The lowest viscosity index of the hydraulic oil determined using the computer program is 101. The viscosity index of the hydraulic oil determined with relation (1) is 58% higher than using the computer program. The viscosity index determined by the graphic method is 50% higher than the one determined by the computer program. The viscositytemperature coefficient has a value of 0.8380. Novelty: Knowing the viscosity index of hydraulic oil is important for starting the engine at high temperatures and at low temperatures. At high temperatures, the oil chemically degrades and the molecules break down. The properties of hydraulic oils depend a lot on the way the hydraulic system works and the limits imposed on them in different conditions. Keywords: Viscosity Index; Viscosity-Temperature Coefficient

Texture analysis and physicochemical characteristics of fermented soymilk gel by different lactic acid bacteria

The high hardness and low water holding capacity (WHC) characteristics of fermented soymilk limit the consumer acceptance of its products. In this study, 4 strains were screened from 126 strains of lactic acid bacteria (LAB) for the fermentation of pure soymilk. The soymilk fermented by the 4 strains had different hardness and WHC levels but similar springiness and kinetic viscosity. Effect of the LAB hydrolyzing protein subunits (7S and 11S) on the particle size, zeta potential, microstructure and intermolecular force of fermented soymilk gel was studied. The results showed that the different degree of protein subunit hydrolysis would affect the particle distribution, zeta potential and intermolecular force in gel, resulting in the difference of microstructure and texture. Hydrophobic protein subunit (7S β subunit, 11S basic subunit) degraded by the LAB enhanced the electrostatic repulsion in the gel, resulting in uneven particle distribution and rough microstructure, which reduced WHC of the gel. When the contribution of hydrophobic force in gel was far greater than that of hydrogen bond, it was unfavorable to the WHC of gel. Hydrolysis of 11S subunit increased the cross-linking sites to raise the content of 20 μm particles and increased the large clusters in the microstructure of gel thus improving the hardness of gel. This study has explained the difference in hardness and WHC of soymilk gel fermented by LAB from a new perspective of protein subunit hydrolysis, and it will help to screen out LAB through protease characteristics to ferment soymilk with low hardness and high WHC.

Synthesis and Characterization of Hydroxylated Plant Oil from Thevetia Peruviana Seed

Oils derived from oil-bearing seeds or certain fruit pieces are known as plant oils or vegetable oils. Using the Soxhlet extraction technique and n-hexane as the solvent, Thevetia peruviana seed oil was extracted from the seed flour. Its physicochemical parameters were determined using standard analytical methods. The hydroxylation process was done through the vigorous stirring of the oil and formic acid with the slow addition of peroxide. The hydroxylated oil was analyzed for functional groups present using Fourier Transform Infrared Spectrometer. The results of the physiochemical parameters showed that Thevetia peruviana oil has acid value (3.88 mg KOH/g), iodine value (93.5 Wij’s), peroxide value (30.0 meq/kg), kinetic viscosity (1.6cp) and saponification value (121.76 mgKOH/g) while the hydroxylated oil has acid value (0.77 mg KOH/g), iodine value (81.40 Wij’s), peroxide value (7.85 meq/kg), kinetic viscosity (7.43cp) and saponification value (162.05 mgKOH/g). The FTIR results showed that both non-hydroxylated and hydroxylated plant oils had the following functional groups OH, CH, C=C, CH2, and C=O. The results showed that the bands were shortened in the hydroxylated oil spectrum except (OH) which became broad indicating the formation of the hydroxyl group by the consumption of the C=C band in the unhydrolyzed oil. The hydroxylation of plant oils using Thevetia peruviana shows the potential of the plant oil to be used as a precursor for the production of industrial intermediates which can replace the dependence on petroleum products.

Effect of liquid filling level on sloshing hydrodynamic characteristic under the first natural frequency

Hydrogen energy is a promising renewable alternative energy and hydrogen storage obtains more interest all over the world. During the transportation of liquid hydrogen, fluid sloshing is inevitable due to low kinetic viscosity. As fluid sloshing has obvious negative effects, the corresponding safety issues should be given detailed considerations. This work aims to study fluid sloshing hydrodynamic performance in a cryogenic fuel storage tank by utilizing volume of fluid (VOF) method. The numerical model validation is conducted by compared with related experimental results. The first natural frequency of the storage tank is selected as external excitation, and influence of initial liquid filling level on fluid sloshing is researched and analyzed. Different fluid sloshing hydrodynamic parameters, including sloshing force, fluid pressure, interface area ratio and interface fluctuation, are simulated. It is found that the initial liquid filling level causes evident influences on fluid sloshing hydrodynamic characteristics. The sloshing hydrodynamic parameters increase with the liquid filling level. The free interface experiences obvious fluctuations subjected to the first natural frequency. Moreover, the interface monitor close to tank wall has large amplitude displacement fluctuations. Generally, the displacement fluctuation increases with the initial liquid filling level. The present work is of significance to understand fluid sloshing hydrodynamics under the natural frequency, and may supply some references to weaken and inhibit large amplitude fluid sloshing.