Effect Of Oil Concentration Research Articles

Experimental study of nucleate boiling heat transfer of refrigerant-oil mixture on various modified surfaces

As a crucial component of refrigeration and heat pump system, the evaporator performance directly affects system efficiency. Due to the lubricating oil in the compressor circulating into the evaporator, studying the nucleate boiling heat transfer (NBHT) of refrigerant-oil mixture is of greater practical and guiding significance. Surface modification technology has opened up a new avenue for enhancing NBHT of refrigerant-oil mixture. Therefore, experimental study was conducted on NBHT characteristics of R134a-POE mixture and R1234ze(E)-POE mixture on smooth surface, initial laser-ablated surface, stabilized laser-ablated surface, machined surface, and composite processed surface. The effects of oil concentration (ω), surface microstructure and surface wettability on NBHT of refrigerant were discussed and analyzed, and the underlying heat transfer mechanisms were elucidated. The research indicates that for NBHT of refrigerant-oil mixture, surface microstructure has a greater impact than surface wettability. To enhance heat transfer coefficient (HTC), it is crucial to establish a surface pattern comprising alternating regions of high and low nucleation sites to mitigate bubble interaction and coalescence. Once this objective is attained, enhancing surface wettability can be contemplated. The addition of oil promotes foaming and induces tornado-shaped bubble group, which facilitate heat transfer. However, the rise in mixture viscosity and surface tension exerts a more pronounced adverse effect on heat transfer, outweighing the positive impacts of foaming and tornado-shaped bubble group. Consequently, the presence of oil diminishes HTC. And as ω and heat flux increase, HTC further decreases. Additionally, the increase in vaporization nuclei on modified surface leads to a higher local ω, the increase in ω further weakens the enhanced heat transfer effect of modified surface, and thus narrows the difference in HTC among various modified surfaces. The research results aim to uncover the mechanisms by which surface wettability, surface microstructure, and lubricating oil affect NBHT of refrigerant.

Development of corn starch-sodium alginate emulsion gels as animal fat substitute: Effect of oil concentration

Emulsion gels were prepared utilizing corn starch (CS), sodium alginate (SA), and corn oil through calcium ion induction for animal-fat analogs. The influence of oil concentration on the rheological properties, microstructure and lipid oxidation of the emulsion gel was analyzed. Results revealed that the emulsion gel containing 30% (v/v) oil exhibited no surplus oil leakage and demonstrated the highest gel strength. The results of the small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that the emulsion gel exhibited the greatest elasticity and deformation resistance when the oil content was 30% (v/v), imparting suitable mouth feel and transport stability as an animal fat substitute. Microstructure analysis indicated that SA crosslinked with Ca2+ to generate a network structure accompanied by the reinforcing effect of starch granules, enabling the dense network to capture an optimal quantity of oil to form a uniform gel network structure. Furthermore, the emulsion gel exhibited markedly lower lipid oxidation compared to bulk oil after 14 days of storage. As a new fat analog system, the CS-SA emulsion gel holds promising potential for applications in the food industry.

Effect of oil concentration, viscosity, and surface tension on tube temperature and heat transfer coefficients of R1234ze(E)/oil spray evaporation on an enhanced tube bundle

Shell-and-tube evaporators are widely used in desalination, refrigeration, and petrochemical industries. The heat transfer process in spray-type evaporators combines the droplets impingement at the top rows of the bundles and falling film evaporation for the bottom rows, with a transitional region in the center of the bundle. Spray evaporators are a promising alternative to flooded-type shell and tube heat exchangers because they run with significantly lower refrigerant charge amounts.This study presents new data for the spray evaporation of low-GWP refrigerant/oil mixtures on an enhanced tube bundle. The experiments involved R134a (HFC) and R1234ze(E) (HFO) paired with synthetic Polyolester (POE68 and POE220) lubricants. The tests utilized a boiling enhanced tube (re-entrant cavity tube) and were conducted at saturation temperatures of −6.7 °C, 2.2 °C and 10 °C (20°F, 36°F and 50°F), with heat flux varying from 3 to 35 kW/m2 and oil circulation ratio (OCR) ranging from 0.4 % to 2 %. With the addition of oil, the bundle heat transfer coefficient (HTC) of refrigerant/oil mixtures decreased by 20–50 % at an OCR of 1.2 % and a heat flux of 13.5 kW/m2, across the tested saturation temperatures. The average wall superheat across the bundle exhibited at least a 48 % increase for all the refrigerant/oil mixtures tested at an OCR of 1.2 %. The viscosity of the refrigerant/oil mixture showed a limited influence on heat transfer compared to surface tension, mainly because the oil concentrations were quite small. Oil promoted a partial dry-out of the tubes, especially at the bottom of the bundle. Foaming was observed and increased with heat flux and oil concentration. Foam sheets on the tube bundle created an additional barrier for the liquid refrigerant to reach the tube heat transfer surfaces and thus decreased the overall bundle heat transfer coefficient.

Effects of Oil Concentration in Flood Cooling on Cutting Force, Tool Wear and Surface Roughness in GTD-111 Nickel-Based Superalloy Slot Milling

Effects of Oil Concentration in Flood Cooling on Cutting Force, Tool Wear and Surface Roughness in GTD-111 Nickel-Based Superalloy Slot Milling

Partitioning of caffeine and quinine in oil-in-water emulsions and effects on bitterness.

The bulk vegetable oil-water partition coefficient of caffeine and quinine was determined by a shake-flask method as log Kow =-1.32 and 2.97. These values were consistent with the effect of oil concentration on the distribution of the bitterants in an oil-in-water emulsion (0-2 and 0-20wt% oil stabilized with 0.125 and 1wt% whey protein isolate, respectively). For example, in a 20% o/w emulsion, approximately 90% of the total caffeine remained in the aqueous phase, whereas in a 2% o/w emulsion, only ∼20% of the quinine remained in the aqueous phase. The intensity of the bitter taste of caffeine and quinine in emulsions was assessed by a large cohort (n=100) of untrained participants. An increase in fat in the emulsions (from 0.5wt% to 2wt% oil emulsions stabilized with 0.125wt% whey protein isolate) caused a significant decrease inperceivedbitternessthat was accompanied by adecrease in the aqueous concentration of the hydrophobic bitterant quinine Specifically, the bitterness of quinine was reduced ∼13% in the o/w emulsion with more fat, and this drop paralleled a drop in the aqueous concentration and was generally consistent with aqueous dose-response functions published elsewhere. For the hydrophilic bitterant caffeine, there was nosignificant change in theperceivedbitterness or aqueous concentration with changing oil concentration. We conclude that the perceived bitterness of a hydrophobic bitterant like quinine in an emulsion depends on the aqueous concentration rather than the overall concentration.

The role of oil concentration on the rheological properties, microstructure, and in vitro digestion of cellulose ether emulsions

The effect of oil concentration (from 5 to 47%) and type of cellulose ether on the rheological properties (flow and linear viscoelasticity), microstructure and oil digestion in o/w cellulose ether emulsions were investigated in the study. Three types of cellulose ethers were used: a hydroxypropyl methylcellulose (HPMC) and two methylcelluloses (MC) with different degrees of methoxyl content. All the emulsions showed shear thinning behaviour. The increase in oil concentration increase the emulsion's viscosity, the viscoelastic moduli G′ and G″, and decreases the loss tangent. The greatest viscosity and viscoelasticity was in the MC with the highest methoxyl content. Oil digestibility was determined by a titration method during in vitro digestion. Compared to a whey protein emulsion (control), the cellulose ether emulsions required a lower NaOH, which indicates lower free fatty acid generation and lower fat digestion. In the cellulose ether emulsions, this decrease in oil digestion was found at all the oil concentrations. A difference in oil digestion kinetics was found between the cellulose ether emulsion (linear) and the control (logarithmic), which was associated to a saturation in the digestive system in the whey protein emulsion. The microstructure after in vitro digestion showed practically no fat globules in the whey protein emulsion, whereas fat globules were observed in the cellulose ether emulsions, which confirms the highest oil digestion in the control emulsion. Cellulose ether emulsions with a wide variety of rheological properties can be obtained by varying cellulose type and oil concentration, with the barrier against fat digestion effective at low and high oil concentrations. • The effect of oil contentin rheology, microstructure and digestion of emulsions were studied. • Viscosity and viscoelasticity increased with oil concentration. • Cellulose ethers showed lower digestibility than a whey protein control. • Different oil digestion kinetics was found among cellulose ether and whey protein control. • Saturation occurs in the whey protein emulsion at higher oil concentration.

Napins and cruciferins in rapeseed protein extracts have complementary roles in structuring emulsion-filled gels

We investigated the complementary roles of napins and cruciferins present in a rapeseed protein mixture (RPM) in structuring emulsion-filled gels (EFGs). Napins are small molecular weight albumins with high interfacial activity, while cruciferins are high molecular weight globulins that form gels upon heat-induced gelation. The role of napins is to stabilize the emulsion droplets, while cruciferins, which were previously found to interact with the adsorbed napin interfacial layer, can build the protein gel network around the droplets. The effects of oil concentration (0–30 wt%) and pH (5 and 7) on the rheological and microstructural properties of EFGs were investigated. In the absence of oil, at pH 5, due to low protein solubility, RPM formed a heterogeneous network built of protein aggregates. At pH 7, RPM was more soluble and formed a homogeneous network built of strand-like protein structures with higher gel firmness. In the presence of emulsion droplets, the gel firmness increased, with a more pronounced reinforcement at pH 5 compared to pH 7. The type of gel network did not change by the presence of emulsion droplets neither at pH 5 nor at pH 7, as suggested from confocal microscopy and the unchanged response to large deformation. This implies that oil did not really change the protein network structure. The emulsion droplets, being stiffer than the protein matrix, and being integrated in the structural matrix, increased the gel firmness. This research shows that the presence of two different proteins with complementary roles in a less purified protein extract, provides a single protein ingredient suitable for structuring food emulsion-filled gels.

Study on polyvinyl chloride nanofibers ability for oil spill elimination

Oil spill is a serious environmental pollution problem that affects the environment and human health. The immediate and efficient removal of oil spill has become an urgent problem. In recent decades, electrospinning technology has become an effective method for fabrication of nanofibers. Electrospun nanofibers have many applications in different fields, such as environment, healthcare, electrical field, and electronics. The present paper has studied the capacity of polyvinyl chloride nanofibers, which have been successfully obtained by electrospinning method for removal of oil from water. The morphology and hydrophobicity of nanofibers were studied. The sorption capacity of nanofibers has been investigated for various oils such as motor oil, hydraulic oil, and crude oil. The rate of oil sorption versus time, the effect of oil concentration, and temperature on the oil sorption capacity were analyzed. The results showed that polyvinyl chloride nanofibers were able to completely absorb oil without absorbing water. In addition, the results of our research showed that polyvinyl chloride nanofiber’s oil sorption capacity is inversely proportional to the temperature. Given these points, our research showed the enormous potential that polyvinyl chloride nanofibers have for removal of oil spill in water, due to their effectiveness and quickly sorption effect.

Olive oil stability in Pickering emulsion preparation from eucalyptus pulp and its rheology behaviour

In the present work, olive oil stability in Pickering emulsion from eucalyptus pulp was determined. The effect of oil concentrations, modified ammonium persulphate cellulose nanocrystals (APS-CNC) concentrations and pH on the drop sizes and distribution of Pickering emulsion were established. The emulsion stability was investigated in terms of zeta potential, %emulsion physical stability (ES) and %remains antioxidant activity. The smallest drop size of 8.00 ± 3.94 µm was obtained at 0.1 wt% of APS-CNC concentration, 10 wt% of oil concentration and pH 7. Also, the maximum %remain antioxidant activity of 44.94 ± 3.66% was acquired at 0.1 wt% APS-CNC concentration at pH 7 after 30 storage days. The rheology behaviour of these Pickering emulsions caused by shear-thinning fluid. This fluid behaviour can be applied to liquid food, cream and oral drug delivery with a nanocarrier.

Effect of lubricant oil on boiling heat transfer and flow patterns of R32 inside a multiport tube

This study experimentally investigated the boiling flow patterns, local heat transfer coefficients, and pressure drops of R32/lubricant oil mixtures flowing inside a horizontal multiport extruded tube having rectangular minichannels. The experiments were carried out in a mass flux range of 50–400 kg m−2 s−1, heat flux range of 5–40 kW m−2, and oil circulation up to 3.7 wt% at an evaporation temperature of 15 °C. The boiling flow patterns were visualized by using a setup that consisted of horizontal multiple square minichannels, each with a hydraulic diameter of 1.0 mm. The heat transfer coefficients of the R32/oil mixtures were lower compared with those of pure R32 and decreased with increasing oil concentration at lower heat fluxes, while they were higher for conditions of higher heat flux and low vapor quality. In addition, the heat transfer coefficients of the mixtures significantly decreased at a lower mass flux and in a higher vapor quality region. The frictional pressure drops of the R32/oil mixtures was higher compared with that of pure R32 and increased with increasing mass flux, vapor quality, and oil concentration. The effect of oil concentration on the pressure drop was significant at the higher vapor quality region. Furthermore, the pressure drops increased with increasing heat flux for lower to middle vapor quality, in contrast to pure refrigerants.

Developed Method for Treatment of Industrial Wastewater from Edible Oil Industry using Membrane Technology

Microorganisms and algae growth on surface water are stimulated in surface water in the presence of effluent wastewater from edible oil industries. This leads to depletion of dissolved oxygen (DO) by eutrophication process result in negative impact on aquatic environment. The new regulation in environment agency and increasing market demand are forcing the industrial sectors to consider finding new solutions and sustainable techniques of the wastewater treatment. In this study, reverse osmosis (RO) membrane filtration has been applied to assess the removal performance of emulsified oil from wastewater. Polysorbate 20 (Tween 20) was used as an oil/water emulsifier. Effect of oil concentrations in terms of chemical oxygen demand (COD) and activated carbon unit on removal efficiency and permeate flux have been studied in details. The results elucidated significant improvement in removal efficiency reached to "98%". The obtained results show promising application of RO membrane (polyamide membrane) at flux "17 L/m2 hr-1". The experiments showed that membrane filtration of wastewater from edible oil is a convenient technique for a possible removal of high concentration of oil (up to 6000 mg/L) with "98%" removal efficiency at permeate flux "17 L/m2 hr-1 "and low fouling rate.

Insecticidal activity of Lantana camara extract oil on controlling maize grain weevils

Postharvest losses are known to be one of the serious constraints upon food security among farmers poor resource in Africa. The use of botanical insecticide in pest management during storage against weevils is often encouraged because synthetic insecticides produce multiple side effects on human and environment. In this study, the insecticidal property of methanol, ethanol, and ethyl acetate extracts of Lantana camara leaf oil and powder for controlling maize weevils, Sitophilus zeamais, was studied. Gas chromatography–mass spectrometry and Fourier transform infrared spectroscopy (FTIR) were used to identify the chemical composition and functional group of solvent extract, respectively. Adult weevil repellency and mortality were studied by the effect of oil concentration at 0% (w/w), 2% (w/w), 3% (w/w), 5% (w/w), 7% (w/w), and 10% (w/w). Repellency effect was also conducted at 6, 12, and 24 h. The number of weevil death increased significantly as exposed time was increased. The extracted oil by the three-solvent fraction had direct repellent and toxic effect to the weevil. From all treatment applied, extracted by methanol fraction had showed highest percentage mortality (74%). The lowest mortality rate was observed in ethyl acetate extract (26%) at 2% (w/w) concentration. The effect of leaf powder and extracted oil on repellency and mortality for insects was due to the presence of bioactive and phytochemical molecules such as Phytol, Pyrroline, Paromomycin, Pyrrolizin, and 1-Eicosano. It was concluded that both L. camara leaf powder and extract oil can be used for the protection of stored maize from infestation S. zeamais.

Impact of oil phase concentration on physical and oxidative stability of oil-in-water emulsions stabilized by sodium caseinate and ultra-high pressure homogenization

In the present study, oil-in-water emulsions were formulated using 5.0% (w/v) of sodium caseinate (SC) and different oil concentrations (10–30%, v/v) by conventional homogenization (CH) and ultra-high pressure homogenization (UHPH, 200–300 MPa). The effect of oil concentration and pressure of treatment on emulsions characteristics and stability was studied. Emulsions were characterized assessing their microstructure, droplet size distribution, rheological properties, emulsifying activity index (EAI), creaming stability by Turbiscan®, and photo-oxidation. UHPH emulsions, especially those treated at 200 MPa, showed smaller droplet size and greater physical stability than CH emulsions. In addition, emulsions containing higher oil volume fractions (20 and 30%) exhibited greater physical and oxidative stability. UHPH emulsions treated at 200 MPa and containing 20% oil content were the most stable emulsions against physical separation and photo-oxidation. These results show that UHPH is a potential technology to enhance the physical and oxidative stability of emulsions containing sodium caseinate as emulsifier for several applications.

Biodegradation of Petroleum Oil Effluents and Production of Biosurfactants: Effect of Initial Oil Concentration

AbstractBiosurfactants have been used in the petroleum oil industry for oil storage tank cleaning, for reducing the viscosity of heavy oil, thereby facilitating recovery, transportation, and pipelining. Also, they are used for microbial enhanced oil recovery either from residual oil in reservoirs or from oily wastewater. The present study is an investigation of biodegradation of petroleum oil effluents using Pseudomonas aeruginosa ATCC 9027 for producing rhamnolipid biosurfactants. The processes were performed in a mechanically agitated, fully baffled, air‐sparged 10 L glass fermenter with a 5 L working volume. The effect of oil concentration (1%, 1.5%, 2%, and 2.5%) on the efficiency of oil biodegradation, rhamnolipid production, surface tension, and bacterial biomass was studied. The fermentation with 1.5% oil concentration gave the highest biodegradation for aliphatic hydrocarbons (98.85%), followed by 2% oil concentration (95% degradation), then with 2.5% oil concentration (80% degradation), and finally with 1% oil concentration (66.8% degradation). Also, the complete biodegradation of polyaromatic hydrocarbons was achieved for all tested oil concentrations. On the other hand, maximum rhamnolipid production of 2.7 g L−1 as rhamnose equivalent and lower surface tension (30.2 mN m−1) were achieved at 2% oil concentration.

Emulsion properties of Asafoetida gum: Effect of oil concentration on stability and rheological properties

Solutions of Asafoetida gum (2% w/w) were used to prepare oil in water emulsion with various oil/gum solution ratios (0.5, 1.0, 2.0, 3.0 and 4.0 v/v). Stability and rheological properties of the emulsions were examined over 28 days of storage at 20 °C. It was revealed that increasing oil volume fraction enhanced the emulsion stability. The results of creaming test showed that emulsions containing oil/gum solution ratio of more than 2.0 (v/v) displayed suitable emulsion stability. Droplet size measurements and microscopic images were representative of flocculation and coalescence with increasing oil volume fraction and time of storage. Emulsion droplet size was increased from 11.11 ± 0.99 μm to 64.01 ± 0.47 μm by increasing oil/gum solution from 0.5 to 4.0. Viscosity got higher values with increasing in oil volume fraction but reduced during the storage time. According to Herschel-Bulkely model, shear thinning behavior was determined for all emulsion samples.

Self-assembly of oil microdroplets at the interface in co-continuous polymer blends

The distribution of hazelnut oil (HNO) in a melt-processed co-continuous blend of poly(ε-caprolactone) (PCL) and polyethylene oxide (PEO) shows the formation of a dense array of self-assembled HNO microdroplets at the PCL/PEO interface, as revealed by electron and Fourier transform infrared (FTIR) microscopy. The microstructure formation is dominated by thermodynamics and corresponds to a partial wetting type of morphology, as predicted by a set of three spreading coefficients, where all three phases meet along a common line of contact. The effects of oil concentration (2.5–10%) on the microdroplets size is investigated at two mixing temperatures, 100 and 150°C. Interestingly, the interfacial microdroplets do not perturb the co-continuous morphology, are particularly stable, and demonstrate almost no size dependence on oil concentration. This work opens up new perspectives for material design comprising active agent transfers at interfaces.

Preparation and applications of microfiltration carbon membranes for the purification of oily wastewater

ABSTRACTMicrofiltration carbon membranes for oily wastewater treatment were fabricated from phenolic resin. The effects of oil concentration, running time, additives and regeneration on the removal of oil from wastewater were investigated. The as-obtained microfiltration membranes possess a macroporosity of 39.0% and meso and microporous volumes of 0.134 m3/g, along with two major pore size distributions around 0.1 μm and 20 nm. They are, respectively, attributed to the constituted particles’ stacking and the precursor pyrolysis. The results showed that the microfiltration membranes can efficiently remove the oil in wastewater. In the presence of ethanol as an additive in solution, the oil concentration is dramatically reduced from initial 200 mg/L in feed to below 10 mg/L in permeate, with an oil rejection of 95.3%.

Physical stability of emulsion encapsulated in alginate microgel particles by the impinging aerosol technique

Emulsion filled alginate microgel particles can be applied as carrier systems for lipophilic actives in pharmaceutical and food formulations. In this study, the effects of oil concentration, emulsifier type and oil droplet size on the physical stability of emulsions encapsulated in calcium alginate microgel particles (20–80μm) produced by a continuous impinging aerosol technique were studied. Oil emulsions emulsified by using either sodium caseinate (SCN) or Tween 80 were encapsulated at different oil concentrations (32.55, 66.66 and 76.68% w/w of total solids content). The emulsions were analysed before and after encapsulation for changes in emulsion size distribution during storage, and compared to unencapsulated emulsions. The size distribution of encapsulated fine emulsion (mean size ~0.20μm) shifted to a larger size distribution range during encapsulation possibly due to the contraction effect of the microgel particles. Coarse emulsion droplets (mean size ~18μm) underwent a size reduction during encapsulation due to the shearing effect of the atomizing nozzle. However, no further size changes in the encapsulated emulsion were detected over four weeks. The type of emulsifier used and emulsion concentration did not significantly affect the emulsion stability. The results suggest that the rigid gel matrix is an effective method for stabilising lipid emulsions and can be used as a carrier for functional ingredients.

Modeling the steady-shear rheological behavior of dilute to highly concentrated oil-in-water (o/w) emulsions: Effect of temperature, oil volume fraction and anionic surfactant concentration

Oil-in-water (o/w) emulsions having different internal phase concentrations have been encountered in the petroleum industry during production, transportation and storage operations. The present study deals with the rheological behavior of o/w emulsions of varying internal phase (oil) concentrations (10–80%) at different temperatures (25–50 °C). A controlled stress rotational viscometer was used with shear rates ranging from 1 to 100 s−1. The emulsions were prepared with an anionic surfactant sodium dodecyl benzene sulfonate (SDBS) and the concentration of the surfactant was varied from 0.5 to 2 w/v %. The emulsions exhibited typical shear thinning behavior and described well by the power law relationship between shear stress and shear rate. Different viscosity models were tested and fitted with the experimental rheological data using rigorous-linear regression analysis. The emulsion viscosity and pseudoplasticity were found to increase with an increase in oil concentration and decrease with an increase in temperature. Droplet size distribution and surface tension (SFT) measurements showed that both droplet size and SFT of emulsions decreased with an increase in the oil concentration, which significantly influenced the emulsion rheology. The effect of oil concentration on the apparent viscosity of emulsions was correlated by an exponential and a polynomial model. Further, a correlation was proposed for the combined effect of volume fraction and temperature on viscosity of emulsions. At higher concentrations of SDBS, the emulsion showed yield stress to flow. The Herschel–Bulkley model described the rheological data significantly well.

Modeling concentration polarization in crossflow microfiltration of oil-in-water emulsion using shear-induced diffusion; CFD and experimental studies

Membrane filtration has become firmly established as a primary technology for ensuring treatment of oily wastewater. A detailed study on concentration polarization (CP) during microfiltration (MF) of oil-in-water emulsions was carried out in order to predict permeate flux decline. A two dimensional computational fluid dynamics (CFD) modeling was conducted using the finite difference method. A combination of molecular and shear-induced diffusion coefficient was employed to describe back-diffusion of oil droplets from the membrane wall toward the bulk. Evaluation of the proposed approach was carried out by comparing the results to the experimental data in which good agreement was observed almost in every operating condition. The effects of oil concentration, trans-membrane pressure (TMP), and cross-flow velocity (CFV) on the model precision were also studied. Finally, the growth rate of CP layer along the membrane length was predicted in different operating conditions, in which the obtained trend was found to be in agreement with the CP theory.