• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1549-1554
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• 2015

This study examined experimentally the characteristics of the flow pattern and particle suspension in an agitated vessel with a bottom baffle. A flow pattern of the particles was shown to increase the upward flow from the center of the agitated vessel bottom. The suspended particles from the experiment found that the particle suspension was promoted by the development of an Ekman boundary layer. The optimal conditions of the impeller, and the agitated vessel bottom baffle within the experimental range were as follows: Impeller, $n_p=6$, d/D=0.5, and b/d=0.3; and bottom baffle, $n_b=6$, $d_b/D=0.5$ and $b_w/D=0.05$.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.17-23
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• 1999

This paper presents the characteristics of the gas flow in the engine cylinder under various intake flow conditins. The particle tracking velovimetry(PTV) was used to anlayze the gas flow pattern and flow field in the cylinder. Effects of tumble intensifying valve(TIV), swirl intensifying valve(SIV) and one-valve deactivated condition on in-cylinder flow patterns were compared with the baseline engine udner 600rpm motoring condition. In addtion, tumbel ration was estimated rwith results of in -cylinder flow fields. Base on experimental results, the tumble ration of in-cylinder flow field has the maximum value at the bottom dead center for the different four inlet conditions. In TIV condition, the tumble ration is 1.35 times larger than that of baseline engine and 1 intake valve deactivated condition is effective to improve in-cylinder swirl motion.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.4
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• pp.377-383
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• 2005

This paper deals with the flow characteristics of air-water two-phase flow in a vertical tube of 10mm I.D. and 600mm in length at an adiabatic condition. The obtained experimental data were covered with the liquid superficial velocity ranging from 0.095m/s to 2.56m/s. and the gas superficial velocity ranging from 0.032m/s to 21.08m/s. The effects of the gas and liquid superficial velocity on the flow pattern transitions, frictional pressure drop, and film thickness and gas-liquid interface roughness were also examined. It was found that the film thickness increased and the liquid film wave length was more longer with the liquid superficial velocity $j_L$ increasing at $j_G$ constant. It was also showed that the frictional pressure drops were experienced in three regions. namely increasing region(bubbly flow), decreasing region (Taylor bubble and slug flows) and re-increasing region (annular flow).

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.342-349
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• 1988

The characteristics of flow pattern transitions in a horizontal cocurrent gas-liquid flow have been investigated by means of a statistical analysis of instantaneous pressure drop curves at an orifice. The dimensionless intensity of pressure drop fluctuation shows a sudden change during the course of flow transitions, indicating that it may be a good measure to identify the flow regime transitions. The probability density function of the curves feature a unique pattern depending upon the flow regimes and the statistical properties of the PDF also have particular ranges for each flow regime. In conclusion, the statistical analysis of instantaneous pressure drops may be a powerful tool for predicting the flow regime transitions.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.1-10
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• 1998

In this paper, we investigated the improvement of characteristics of knock, emission and fuel consumption rate by optimizing the location and size of water transfer holes in cylinder head gasket without change of engine water jacket design itself. The cooling system was modified in the direction of reducing the metal temperature in the head and increasing the metal temperature in the block. The optimization of water transfer holes in cylinder head gasket was obtained by "flow visualization test". The water transfer holes were concentrated in front side of the engine in order to reduce thermal boundary layer in the water jacket of No. 2 and No. 3 combustion changer in the cylinder head, which would have a large knock intensity, and increase thermal boundary layer in the water jacket of the cylinder block. When the modified coolant flow pattern was applied as proposed in this paper, the knock characteristic was improved. The spark timing was advanced up to 2$^{\circ}$ in low and middle speed range at a full load. In addition, HC emission at MBT was reduced by 5.2%, and the fuel consumption rate was decreased up to 1% in the driving condition of 2400 rpm and 250 KPa. However, since this coolant flow pattern mentioned in this paper might deteriorate the performance of vehicle cooling system due to the coolant flow rate reduction, a properly optimized point should be obtained. obtained.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.162-169
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• 2009

In summer electrical energy is consumed in very high rate. It is used to operate conventional air conditioning system. Hot and humid air can germinate mould spores, encourage ill health, and create physiological stress (discomfort). Dehumidifier solar cooling effect is the one alternative solution saving electrical energy. We use surplus heat energy in the summer, to get cooling effect and then to get human reach to comfort condition. These devices have two system, dehumidifier and regeneration system. This paper will be focus in dehumidifier system. Dehumidifier system use for absorbing moisture in the air and decreasing air temperature. When the liquid desiccant as strong solution contact with the vapor air in the packed tower, it works. The heat and mass transfer performances of flow pattern in the packed tower of dehumidifier are analyzed and compared in detail. In this experiment was introduced, the flow patterns are parallel flow and counter flow. The performance of these flow patterns will calculate from air side. Which is the best flow pattern that gave huge mass transfer rate? The proposed dehumidifier flow pattern will be helpful in the design and optimization of the dehumidifier solar cooling system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.833-846
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• 1988

Two-phase flow heat transfer phenomena with flash evaporation inside a vertical tube were studied experimentally. Void fractions were measured using electrical probes, and the flow patterns were identified from the output voltage signal itself. The flow pattern as well as the beat transfer rates were changing along the axial distance from the tube inlet with the system pressure. As the pressure inside the tube decreases with fixed inlet temperature, the overall heat transfer coefficient through the tube wall and the boiling heat transfer coefficient inside the tube increase whereas the condensation heat transfer coefficient outside the tube decreases. The boiling heat transfer coefficient inside the tube measured by the experiments appeared to be somewhat larger than the value obtained from the Chen's correlation. Also, the flow patterns identified from present experiments are at the larger quality region of the low pattern map based on the transition criteria of Mishima and Ishii. This may be due to the non-equilibrium flashing phenomenon occurred at the nozzle exit and the tube inlet ; this also implies that the flow pattern of the two-phase flow depends strongly on the inlet conditions.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1507-1519
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• 2003

The two-phase flow patterns for both non-loop and loop type oscillating capillary tube heat pipes (OCHPs) were presented in this study. The detailed flow patterns were recorded by a high-speed digital camera for each experimental condition to understand exactly the operation mechanism of the OCHP. The design and operation conditions of the OCHP such as turn number, working fluid, and heat flux were varied. The experimental results showed that the representative flow pattern in the evaporating section of the OCHP was the oscillation of liquid slugs and vapor plugs based on the generation and growth of bubbles by nucleate boiling. As the oscillation of liquid slugs and vapor plugs was very speedy, the flow pattern changed from the capillary slug flow to a pseudo slug flow near the annular flow. The flow of short vapor-liquid slug-train units was the flow pattern in the adiabatic section. In the condensing section, it was the oscillation of liquid slugs and vapor plugs and the circulation of working fluid. The oscillation flow in the loop type OCHP was more active than that in the non-loop type OCHP due to the circulation of working fluid in the OCHP. When the turn number of the OCHP was increased, the oscillation and circulation of working fluid was more active as well as forming the oscillation wave of long liquid slugs and vapor plugs in the OCHP. The oscillation flow of R-142b as the working fluid was more active than that of ethanol and the high efficiency of the heat transfer performance of R -142b was achieved.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.10
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• pp.1460-1468
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• 2003

An experiment was conducted to quantify the flow of soluble non-ammonia nitrogen (SNAN) in the liquid phase of ruminal (RD) and omasal digesta (OD), and to investigate diurnal pattern in SNAN flow in OD. Five ruminally cannulated Finnish-Ayrshire dairy cows in a $5{\times}5$ Latin square design consumed a basal diet of grass silage and barley grain, and that supplemented with four protein feeds (kg/d DM basis) as follows: skimmed milk powder (2.1), wet distiller' solubles (3.0), untreated rapeseed meal (2.1) and treated rapeseed meal (2.1). Ruminal digesta was sampled using a vacuum pump, whereas OD was collected using an omasal sampling system at 1.0 h interval during a 12 h feeding cycle. Both RD and OD were acidified, centrifuged to remove microbes and precipitated with trichloroacetic acid followed by centrifugation. The SNAN fractions (free amino acid (AA), peptide and soluble protein) in RD and OD were assessed using ninhydrin assay. Free AA, peptide and soluble protein averaged 60.0, 89.4 and 2.1 g/d, respectively, for RD, and 81.8, 121.5 and 2.5 g/d, respectively, for OD. Although free AA flow was relatively high, mean peptide flow was quantitatively the most important fraction of SNAN, indicating that degradation of peptide to AA rather than hydrolysis of soluble protein to peptide or deamination may be the most limiting step in rumen proteolysis. Diurnal pattern in flow of peptide including free AA in OD during a 12 h feeding cycle peaked 1 h post-feeding, decreased by 3 h post-feeding and was relatively constant thereafter. Protein supplementation showed higher flow of peptide including free AA immediately after feeding compared with no supplemented diet. There were no differences among protein supplements in diurnal pattern in flow of peptide including free AA in OD.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1532-1534
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• 1999

Electrical treeing phenomenon, regarded as pre-breakdown which accelerates aging process leading an insulation to the complete breakdown, is with no doubt extremely fatal to the performance of the insulation. Investigated in this paper is electrical treeing representing local dielectric failure according to flow pattern, the flow history of liquid polyethylene formed during the extrusion process. Experiments of electrical tree initiation by means of ramp tests were conducted using newly developed electrode system with point-to-point structure. Constant voltage tests were also carried out with the electrode system to estimate the life time of the insulation. Results were analyzed using statistical method such as Weibull distribution.