• Korean Journal of Food Science and Technology
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• v.4 no.3
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• pp.200-205
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• 1972

Effects of several different petroleum fractions (LGO, HGO, VGO, Diesel oil, SP(E), HGO-wax, L/M-wax), stepwise addition of calculated amounts of HGO at defined intervals, recycling of spent media on cell growth of Candida tropicalis KIST 351 were studied using $2.5{\ell}$ fermenter by batch process. In addition, continuous cultivation of the yeast was also performed in the light of biomass production using $28{\ell}$ fermenter with LGO. 1) Cell concentration, yield on the basis of gas oil and n-paraffin with the petroleum fractions were in the range of $11{\sim}15g/{\ell}$, $10{\sim}12%$ and $77{\sim}82%$, respectively. 2) By stepwise addition of the gas oil, cell concentration and yield on the oil were increased up to 18.9 g/land 13%, respectively. 3) Spent medium slowed emulsifying ability of hydrocarbon and stimulating effect on the cell growth. Without additional supplementation of $Mg^{++}$ up to 20% of spent medium could be reused, while by adding of the $Mg^{++}$, 50% of medium could be recycled. 4) Optimum condition of continuous cultivation for biomass production was attained at the dilution rate of $D=0.1{\sim}0.125\;hr^{-1}$. Maximum yield coefficient on consumed n-paraffin was 0.94 at $D=0.1\;hr^{-1}$, however, 24% of supplied n-paraffin in the media was not utilized at this dilution rate.

• Clean Technology
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• v.26 no.3
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• pp.204-210
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• 2020

In this study, the ignition characteristics of bio jet fuel (Bio-7629, Bio-5172) produced by F-T process and petroleum-based jet fuel (Jet A-1) were compared and analyzed. The ignition delay time of each fuel was measured by means of a combustion research unit (CRU) and the results were explained through an analysis of the properties and composition of the fuel. The ignition delay time of Bio-5172 was the shortest while that of Jet A-1 was the longest because Jet A-1 had the highest surface tension and Bio-5172 had the lowest viscosity in terms of fuel properties that could affect the physical ignition delay time. As a result of the analysis of the constituents' type and ratio, 22.8% aromatic compounds in Jet A-1 could generate benzyl radical, which had low reactivity during the oxidation reaction, affecting the increase of ignition delay time. Both Bio-7629 and Bio-5172 were composed of paraffin only, with the ratio of n-/iso- being 0.06 and 0.80, respectively. The lower the degree of branching is in paraffin, the faster the isomerization of peroxy radical is produced during oxidation, which could determine the propagation rate of the ignition. Therefore, Bio-5172, composed of more n-paraffin, possesses shorter ignition delay time compared with Bio-7629.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.545-549
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• 2013

Liquid paraffin is a mixture of heavier alkanes derived from petroleum. It can be used as a lubricant in processing machinery, as a coating agent, or as a releasing agent. The purpose of this study was to analyze liquid paraffins in foods by using a gas chromatography-flame ionized detector (GC-FID). Liquid paraffin was extracted from the food samples using n-hexane. Non-polar aromatic or olefinic co-extractives were removed by alkaline permanganate oxidation followed by clean up on an aluminium oxide SPE cartridge before the GC-FID analysis. The results of recovery tests were 91.5-103.2%. Based on this optimized method, we investigated the amount of liquid paraffin in various food samples purchased from domestic markets. The levels of liquid paraffin in bread were $95.5{\pm}156.0$ mg/kg (0.008%), those in capsules were $40.2{\pm}54.5$ mg/kg (0.001%), and those in dried fruits and vegetables were $3.0{\pm}18.1$ mg/kg (0.0001%). No liquid paraffin was detected in fresh fruits and vegetables. We propose that our method can be used to monitor and detect liquid paraffin in foods for food safety management.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.5
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• pp.552-561
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• 2006

The single droplet combustion characteristics of diesel fuel and low quality oil with additive oxygenate and paraffin under high ambient temperature and atmospheric pressure were investigated in the study. The results of the study may are concluded as follows: In the combustion of diesel fuel and low quality oil droplet with additive of oxygenate and paraffin. the dimensionless droplet size of $(D/Do)^2$ was linearly decreased with time. A fuel droplet with low boiling temperature additives and in high boiling temperature base fuel evaporates and burns faster than usual base fuel. Especially. these trends were remarkably obtained by decreasing boiling point and increasing blending contents of additives in case of oxygenated agents rather than n-paraffin agents. This rapid burning may result from so-called 'micro-explosion' and its burning intensity varies with the types of additives. The results above may suggest that rapid evaporation of oxygenate additive in the middle stage of combustion can contribute much to combustion improvement of blended fuels.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.83-84
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• 2002

For estimation of chain-matching phenomena between normal paraffin as a solvent and straight-chain fatty acid as an additive, the density measurement of n-dodecane, n-tetradecane and n-hexadecane were carried out at oil temperature 313K and pressure up to 1.3 GPa. Their solidification pressure were easily determined by the appearance of molecular crystal, abrupt volumetric contraction and generation of heat of solidification and showed minima under the matching condition. The bulk modulus K of molecular crystal was evaluated using phase diagram. The bulk modulus showed maxima under the each matching condition. The chain matching effect on the bulk modulus beyond the scope of the interfacial phenomena are confirmed.

• 한국기계연구소 소보
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• s.19
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• pp.23-30
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• 1989

Heat transfer phenomena of solidification process of the phase change material within cylindrical can is studied experimentally. N-Eicosane paraffin wax is used for phase change material and its melting temperature is 309.8 K. In order to achieve higher heat transfer rate of latent heat storage apparatus, fins in made of copper are used in the cylindrical can. If there are fins in cylindrical can, we can know that the inward latent heat energy in paraffin can be effectively transfered to cooling water than if finless.

• Journal of the Korean Chemical Society
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• v.16 no.4
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• pp.208-213
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• 1972

Isostric heats of adsorption of amines on paraffin and polyethyleneglycol were measured by gas chromatography. Value with polyethyleneglycol were significantly higher than those with paraffin due to the N-H...O bonding. The contribution of C-H...O bonding to the isosoteric heats of adsorption was negligible. The additional heats of adsorption observed as the sample size increased also increased as the number of amino hydrogen atoms decreased. This tendency was more significant with polyethyleneglycol indicating that strong directing force of amino hydrogen of primary and secondary amines to the surface hinder lateral attractive interaction which could be favored with free orientation.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.620-627
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• 2019

In this study, ignition delay characteristics of various bio aviation fuels (Bio-ADD, Bio-6308, Bio-7720) produced by HEFA process using different raw materials were compared and analyzed. In order to confirm the feasibility of applying bio aviation fuel to actual system, ignition delay characteristics of petroleum-based aviation fuel (Jet A-1) and blended aviation fuel (50:50, v:v) also analyzed. Ignition delay time of each aviation fuel was measured by using CRU, surface tension measurement and GC/MS and GC/FID analysis were performed to interpret the results. As a result, ignition delay time of Jet A-1 was the longest at all temperature because it contains aromatic compounds about 22.8%. The aromatic compounds can produce benzyl radical which is thermally stable and has low reactivity with oxygen during decomposition process. In the case of bio aviation fuels, ignition delay times were measured similarly because the ratio of n-paraffin/iso-paraffin constituting each aviation fuel is similar (about 0.12) and the composition ratio of cycloparaffin also has no difference. In addition, ignition delay times of blended aviation fuels (50:50, v:v) were measured close to the mean value those of each fuel so it was confirmed that it can be applied without any changing or improving of existing system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.231-239
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• 1999

The microstructure of ceramic composite has been found to be governed by the type and amount of the secondary phase, the sintering aid, and the sintering conditions such as sintering temperature, pressure and holing time. Moreover, tribological properties are strongly dependent on microsturcture of composite and operating conditions. In this study, silicon nitride with various amount of magnesia as a sintering aid were prepared and sintered by a hot pressing (HP) technique. Microstructure, mechanical properties (hardness, strength, and fracture toughness), and tribological properties in different environments of $Si_{3}N_{4}$ (in air, water, and paraffine oil) were investigated as a function of MgO content in $Si_{3}N_{4}$. As increasing the amount of MgO in $Si_{3}N_{4}$, the glassy phase in the grain boundaries enlarged the $\beta$-phase elongated grains, and also degraded the Hertzian contact damage resistance. Tribological behaviors in air was seemed to be determined by fracture toughness of $Si_{3}N_{4}$, and those in water and paraffin oil was seemed to be determined by hardness as well as strength. Since glassy grain-boundary phase (MgO) in $Si_{3}N_{4}$ expected to be reacted with water during sliding, such tribochemical reaction reduced wear. In paraffin oil under a higher applied load, the initial sliding dominated wear rate because of Hertzian contact damage.

• Korean Journal of Food Science and Technology
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• v.6 no.4
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• pp.231-240
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• 1974

The growth of a mixed yeast culture consisting of Canda tropicalis var. KIST 76 and Tricosporon cutaneum KIST 76-H was compared with that of pure cultures under pilot plant conditions. The mixed culture was judged stable based on the nearly constant ratio of the two organisms at the completion of fermentation. We obtained higher cell yields, protein content and productivity in the mixed culture on n-paraffin than the pure culture of C. tropicalis var. KIST 76. T. cutaneum KIST 76-H did not grow on n-paraffin medium. With the batch cultivation of mixed organisms on n-paraffin, the specific growth rates during the exponential growth phase were 0.24-0.33 $hr^{-1};$ cell yields were 96-106% and productivities were 2.9-3.6g/l. hr. The cells obtained contained 55-58% crude protein and 5.5-6.3% lipid. The critical value of dissolved oxygen concentration Ccrit. and saturation constant, km, are approximately 1.5 ppm and 0.228 ppm respectively. Also we established the optimal conditions for the mixed culture in batch fermentation.