• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.11-20
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• 1999

In this paper all the photoelectric times of minimum for the triple star SW Lyn have been analyzed in terms of light-time effect due to the third-body and secular period decreases induced by mass transfer process. The light-time orbit determined recently by Ogloza et al.(1998) were modified and improved. And it is found that the orbital period of SW Lyn have been decreasing secularly. The third-body revolves around the mass center of triple stars every $5^y.77$ in a highly eccentric elliptical orbit(e=0.61). The third-body with a minimum mass of $1.13M_{odot}$ may be a binary or a white dwarf. The rate of secular period-decrease were obtained as ${Delta}P/P=-12.45{ imes}10^{-11}$, implying the mass-transfer from the massive primary star to the secondary. The mass losing rate from the primary were calculated as about $1.24{ imes}10^{-8}M_{odot}/y$. It is noticed that the mass-transfer in SW Lyn system is opposite in direction to that deduced from it's Roche geometry by previous investigators.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.11-16
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• 2010

The evaporation heat transfer characteristics of propane(R-290) in horizontal small diameter tubes were investigated experimentally. The test tubes have inner diameters of 1 mm and 4 mm. Local heat transfer coefficients were measured at heat fluxes of 12, $24\;kW/m^2$, mass fluxes of 150, $300\;kg/m^2s$, and evaporation temperature of $15^{\circ}C$. The experimental results showed that the evaporation heat transfer coefficient of R-290 has an effect on heat flux, mass flux, tube diameter, and vapor quality. The evaporation heat transfer of R-290 has an influenced on nucleate boiling at low quality and convective boiling at high quality. The evaporation heat transfer coefficient of R-290 increases with decreasing inner tube diameter. And the evaporation heat transfer coefficient of R-290 is about 1~3 times higher than that of R-134a.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.11
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• pp.906-914
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• 2006

The present paper dealt with an experimental study of boiling heat transfer characteristics of R-290. Pressure gradient and heat transfer coefficient of the refrigerant flow inside horizontal smooth minichannel were obtained with inner tube diameter of 3.0 mm and length of 2,000 mm. The direct electric heating method was applied for supplying a heat to the refrigerant uniformly. The experiments were conducted with R-290 purity of 99.99%, at saturation temperature of 0 to $10^{\circ}C$, a mass flux range of $50{\sim}250kg/m^2s$, and a heat flux range of $5{\sim}20kW/m^2$. The heat transfer coefficients of R-290 increased with increasing mass flux and saturation temperature, wherein the effect of mass flux was higher than that of the saturation temperature. Heat flux has a low effect on the increasing of heat transfer coefficient. The heat transfer coefficient was compared with six existing heat transfer coefficient correlations. The Zhang et al.'s correlation (2004) gave the best prediction of heat transfer coefficient. A new correlation to predict the two-phase flow heat transfer coefficient was developed based on the Chen correlation. The new correlation predicted the experimental data well with a mean deviation of 11.78% and average deviation of -0.07%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1214-1222
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• 2001

The present study investigated the effect of diameter and length on the absorption performance of a vertical falling film type absorber using $LiBr-H_2$O solution of 60 wt%. The parameters were diameter of absorber (17.2, 23.4, 31.1 mm), length of absorber (771, 1150, 1528 mm), and film Reynolds numbers (50, 70, 90, 110, 130, 150). As the diameter of the absorber was increased, the absorption mass flux, Sherwood number, heat flux, and heat transfer coefficient were increased, in which Sherwood number and heat transfer coefficient were increased up to 13% and 30% respectively. As the length of the absorber was increased, the total absorption rate and heat transfer coefficient were increased by 37% and 35% respectively, while the absorption mass flux was decreased.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.645-652
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• 1994

The leading edge of a turbine blade was simulated as a circular cylindrical surface. The effect of free-stream turbulence on the mass transfer upstream of the injectionhole has been investigated experimentally. The effects of injection location, blowing ratio on the Sherwood number distribution were examined as well. The mass transfer coefficients were measured by a naphthalene sublimation technique. The free-stream Reynolds number based on the cylinder diameter is 53,000. Other conditions investigated are: free-stream turbulence intensities of 3.9% and 8.0%, injection locations of $40^{\circ}$, $50^{\circ}$, and $60^{\circ}$ from the front stagnation point of the cylinder, and blowing ratios of 0.5 and 1.0. The role of the horseshoe vortex formed upstream edge of the injected jet is dicussed in detail. When the blowing ratio is unity, and the coolant jet is injected at $40^{\circ}$, the mass transfer upstream of the jet is not affected by the coolant jet at all. On the other hand, when the injection hole is located beyond $50^{\circ}$, the mass transfer upstream edge of the injection hole suddenly increases due to the formation of the horseshoe vortex, but it dereases as the free-stream turbulence intensity increases because the strength of the horseshoe vortex structure becomes weakened. The role of the horseshoe vortex is clearly evidenced by placing a rigid rod at the injection hole instead of issuing the jet. In the case of the rigid rod, the spanwise Sherwood number upstream of the injection hole is much larger due to the intense influence of the horseshoe vortex.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1036-1042
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• 1998

It was investigated that the extraction of Cr(VI) from aqueous solution into the organic TDA and the stripping(back extraction) of Cr(VI) from the Cr(VI)-TDA complex into NaOH aqueous solution by hydrophobic hollow fiber membrane. It was found that the mass transfer rates of stripping process were smaller than those of the extraction process. This result was expected that membrane resistance, neglected in the extraction process, acts on the stripping process when organic phase flow in the tube side of the hydrophobic membrane. Hollow fiber modules were made by potting the desired number(60, 100, 150, 300fibers). We also examined the effect of flow rates of aqueous and organic phase on the mass transfer rate in the membrane modules. From these experiments, we identified for the extraction process by using hydrophobic membrane, the effect of flow rate of aqueous phase on the mass transfer rate was significant, but that of organic phase was negligible one. In the stripping process, however, mass transfer rate depend neither flow rate of aqueous(stripping solution) phase nor that of organic(Cr-TDA complex) phase.

• Membrane and Water Treatment
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• v.1 no.2
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• pp.159-169
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• 2010

The effect of external recycle on the performance of dialysis in countercurrent-flow rectangular membrane modules was investigated both theoretically and experimentally. Theoretical analysis of mass transfer in parallel-flow device with and without recycle is analogous to heat transfer in parallel-flow heat exchangers. Experiments were carried out with the use of a microporous membrane to dialyze urea aqueous solution by pure water. In contrast to a device with recycle, improvement in mass transfer is achievable if parallel-flow dialysis is operated in a device of same size with recycle which provides the increase of fluid velocity, resulting in reduction of mass-transfer resistance, especially for rather low feed volume rate.

• Journal of Hydrogen and New Energy
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• v.15 no.2
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• pp.144-151
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• 2004

The effect of the cobalt content on the thermodynamic and, heat and mass transfer properties of the $MmNi_{5-y}B_{y-z}C_z(y=0.5{\sim}1.5,\;z=0.5)$hydrogen storage alloys has been studied systematically. The P-C isotherms curves show that with increasing cobalt content in the alloys, the plateau pressure of the hydrogen absorption and desorption and enthalpy(${\Delta}H$) increases steeply and the plateau region becomes flat, while entropy(${\Delta}S$) decreases. Also at the constant cobalt content the hydrogen transfer rate decreases with the reaction temperature, while the initial reaction kinetics increases. But the initial reaction with hydrogen completes within 1min, although the reaction proceeds about 30minutes thereafter.

• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.585-595
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• 2001

A series of experiments have been carried out to investigate the effects of non-condensable gas on the direct contact film condensation of vapor mixture under an adiabatic wall condition. The average heat transfer coefficient of the direct contact condensation was obtained at the atmospheric pressure with four main parameters ; air-mass fraction, mixture velocity, film Reynolds number, and the degree of water film subcooling having an influence on the condensation heat transfer coefficient. With the analysis of 88 experiments, a correlation of the average Nusselt number for direct contact film condensation of steam/air mixture at an adiabatic vertical wall was proposed as functions of film Reynolds number, mixture Reynolds number, air mass fraction, and Jacob number. The average heat transfer coefficient for steam/air mixture condensation decreased significantly while air mass fraction increased. The average heat transfer coefficients also decreased as the Jacob number increased, and were scarcely affected by the film Reynolds number below a mixture Reynolds number of about 245,000.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.191-198
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• 2001

A numerical analysis of the heat and mass transfer and pressure drop characteristics in modular shell and tube bundle heat exchanger was carried out. Finite Concept Method based on FVM and $k-\varepsilon$ turbulent model were used for this analysis. Condensation heat transfer enhanced total heat transfer rate $4\sim8%$ higher than that of dry heat exchanger. With increasing humid air inlet velocity, temperature and relative humidity, and with decreasing heat exchanger aspect ratio and cooling water velocity, total heat and mass transfer rate could be increased. Cooling water inlet velocity had little effect on total heat transfer.