• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.554-557
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• 2008

In this study, two types of central flow distributor designs are presented and compared to obtain the optimal compact design which has the least flow resistance and the uniform flow distribution in a vehicular fuel cell stack. For effective and reliable prediction on the thermo-flow characteristics of the reactants flow over the entire fuel cell stack domain, open channel flow in the bipolar plates of the power generating cells were simulated by applying a simplified flow resistance model with an empirical porous concept. A number of case studies were performed to figure out an optimal configuration of a central flow distributor device in terms of the time-dependent thermo-flow behavior and load-dependent flow distribution. The results showed that the stable and load-independent thermo-flow uniformity is very design specific, which is closely associated with the design of central manifolding devices in order to achieve the enhanced volumetric power density and the reliable long-lasting operating of fuel cells.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.107-118
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• 2005

An experimental investigation was made to study two-phase flow distribution in a T-type distributor of slit fin-and-tube heat exchanger using R-22. Experiments were carried out under the conditions of saturation temperature of $5^{\circ}C$ and mass flow rate varying from 0.6 to 1.2kg/min. The inlet air has dry bulb temperature of $27^{\circ}C$, relative humidity of 50% and air velocity varying from 0.63 to 1.71m/s. A comparison was made between the predictions from the previously proposed tube-by-tube method and the present experimental data for the heat transfer rate of evaporator. Results show that $82.5\%$ increase of air velocity is needed for T-type distributor with four outlet branches than that of two outlet branches under the superheat of $5^{\circ}C$, which resulted in increasing of air-side pressure drop of $130\%$ for the former as compared to the latter.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.272-277
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• 2005

Characteristics of bubbling behavior and bubble properties were investigated in a gas-liquid countercurrent bubble column of in diameter 0.152 m and 3.5 m in height, respectively. Effects of gas and liquid velocities and bubble distribution mode(even, wall-side, central or asymmetric distribution) on the bubble properties such as chord length, frequency, rising velocity and holdup in the reactor were measured and examined by means of dual resistivity probe method. The bubble size, frequency and holdup increased with increasing gas($U_G$) or liquid velocity($U_L$). The rising velocity of bubbles increased with increasing $U_G$, whereas decreased with increasing $U_L$. The uniformity of bubble size distribution and bubble holdup decreased when the distribution mode of bubbles at the gas distributor was changed from even to wall-side, central or asymmetric. The central distribution of bubbles was better than asymmetric mode but worse than wall-side distribution, in considering the bubble holdup and uniformity of distribution.