• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.9-15
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• 2005

A bioartificial liver (BAL) is a medical device entrapping living hepatocytes or immortalized cells derived from hepatocytes. Many efforts have already been made to maintain the functions of the hepatocytes in a BAL device over a long term. However, there is still some uncertainty as to their efficacy. and their limitations are unclear. Therefore, it is important to quantitatively evaluate the metabolic functions of a BAL. In previous studies on in vitro BAL devices, two test methods, an initial bolus loading and constant-rate infusion plus initial bolus loading, were theoretically carried out to obtain physiologic data on drugs. However, in the current study, the same two methods were used as a perfusion model and derived the same clearance characterized by an interrelationship between the perfusate flow rate and intrinsic clearance. The interrelationship indicated that the CL increased with an increasing perfusate flow rate and approached its maximum value, i.e. intrinsic clearance. In addition, to set up an in vivo BAL system, the toxic plateau levels in the BAL system were calculated for both series and parallel circuit models. The series model had a lower plateau level than the parellel model. The difference in the toxic plateau levels between the parallel and series models increased with an increasing number of BAL cartridges.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.395-397
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• 2006

Air interlacing serves to protect the yarn against damage, strengthens inter-filament compactness or cohesion, and ensures fabric consistency. The air interlacing nozzle is used to introduce intermittent nips to a filament yarn so as to improve its performance in textile processing. The effect of various interlacing nozzle geometries on the interlacing process was studied. The geometries of interlacing nozzles with single or multiple air inlets located across the width of yarn channels are investigated. The basis case is the yarn channel, with a perpendicular main air inlet in the middle. Other cases have main air inlets, slightly inclined double sub air inlets, The yarn channel cross sectional shapes are either semicircular or rectangular shapes. The compressed impinging jet from the main air inlet hole hits the opposing bottom wall of the yarn channel, is divided into two branches, joins with the compressed air coming out from sub air inlet at the bottom and creates two free jets at both ends of the yarn channel. The compressed air movement in the cross-section consists of two opposing directional vortices. The CFD-FASTRAN flow parallel solver was used to perform steady simulations of impinging jet flow inside of the interlace nozzles. The vortical structure and the flow pattern such as pressure contour, particle traces, velocity vector plots inside of interlace nozzle geometry are discussed in this pater.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.1-8
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• 2013

In this study, we performed three-dimensional CFD analysis to investigate the effect of the rotor blade sweep of a partial admission supersonic turbine on the stage performance and the flow field. The computations are conducted for three different sweep cases, No sweep(NSW), Backward sweep(BSW), and Forward sweep(FSW), using flow analysis program, FLUENT 6.3 Parallel. The results of the BSW model show reduced mass flow rates of tip leakage and increased total-to-static efficiency. The strength of leading edge bow shock was decreased a little with BSW model. And the BSW model also shows a good performance around the hub region compared to other models.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3114-3119
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• 2008

Relatively high convective flow exists in the under-rib regions of a gas diffusion layer (GDL) when serpentine flow fields are employed in a PEMFC. This under-rib convection is believed to be favorable for the performance of PEMFCs, by enabling more effective use of catalysts in the under-rib regions. From the fact that the under-rib convection in a GDL is directly proportional to the permeability of the GDL, computational fluid dynamics (CFD) simulations were performed to discover the relationship between the GDL permeability and the PEMFC performance. Single-, triple-, and quintuple-path parallel serpentine flow fields for $9\;cm^2$ active cell area were considered while changing the GDL permeability from $1{\times}10^{-12}$ to $5{\times}10^{-11}m^2$. The results showed that higher GDL permeability generally resulted in better performance of PEMFCs, but the degree of performance enhancement became smaller as the parallel path number increased. The effects of the permeability on the local variables were also discussed.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.630-635
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• 2008

A dynamic model has been developed to investigate the operability of a single and double-effect solar energy assisted parallel type absorption chiller. In the study, main components and fluid transport mechanism have been modeled. Flow discharge coefficients of the valves and the pumps were optimized for the double-effect mode with solar-heated water circulated. The model was run for the single mode with solar energy supply only and the solar/gas driving double effect mode. And the cases of the double mode with and without the solar energy were compared. From the simulation results, it was found that the present configuration of the chiller is not capable of regulating solution flow rates according to variable solar energy input. And the single mode utilizing the solar energy only is not practical. It is suggested to operate the system in the double mode and the flow rate control system adaptive to variable solar energy input has to be developed.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.245-251
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• 2007

The performance of fuel cell is enhanced with increasing reaction surface. Narrow flow channels in flow plate cause increased pumping power. Therefore it is very important to consider the pressure drops in the flow channel of fuel cell. Previous research for pressure drop for micro channel of fuel cell was focused on effects of various configuration of flow channel without electrochemical reaction. It is very important to know pressure loss of micro flow channel with electrochemical reaction because fluid density in micro channel is changed due to chemical reaction. In this paper, it is investigated that the pressure drops in micro channel of various geometries at anode and cathode with electrochemical reaction and compared them to friction coefficient (fRe), velocity, pressure losses for corresponding non reacting flow channel. The results show that friction factors for cold flow channel could be used for parallel and bended flow channel for flow channel design of fuel cell. In the other hand, pressure drop for serpentine flow channel is the lowest among flow channels due to bypass flow across gas diffusion layer under reacting flow condition although its pressure drop is highest for cold flow condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.2
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• pp.1-11
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• 2002

In the present study, a parallel DSCM technique based on a cell-based data structure is developed for the efficient simulation of rarefied gas flows especially od PC clusters. Dynamic load balancing is archieved by decomposing the computational domain into several sub-domains and accounting for the number of particles and the number cells of each domain. Mesh adaptation algorithm is also applied to improve the resolution of the solution and to reduce the grid dependency. It was demonstrated that accurate solutions can be obtained after several levels of mesh adapation starting from a coars initial grid. The method was applied to a two-dimensioanal supersonic leading-edge flow and the axi-symmetric Rothe nozzle flow to validate the efficiency of the present method. It was found that the present method is a very effective tool for the efficient simulation of rarefied gas flow on PC-based parallel machines.

• Journal of Energy Engineering
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• v.2 no.3
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• pp.251-257
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• 1993

The purpose of this study is to obtain an improved interpretation of heat transfer phenomena between blocks and fluids in the parallel conducting plates. Flow is two-dimensional, incompressible steady laminar flow over rectangular blocks, representing finite heat source on parallel plate. Heat transfer phenomena, temperature of blocks and heat transfer into the flow field are investigated for different spacings between blocks and Reynolds numbers. Results indicate that Nusselt number on the far upstream corner of the block was higher than that of any part of the block. As Reynolds number and spacings of blocks increased, Nusselt number increased. The distribution of local Nusselt number on the top surface of the conducting plate is similar to the case with insulated plate. Temperature of the block which has heat source in half cubage was approximately twice as high as temperature of the block which has heat source in whole cubage. As Reynolds number and spacings of blocks increased, overall temperature decreased. The peak value of block temperature occurred at position shifted to the right or upper right from center. The maximum temperature of block can be expressed as a function of Reynolds number, spacings between blocks, position of maximum temperature of each block and then it is possible to predict the maximum temperature of blocks.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.439-448
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• 2001

A two-dimensional finite difference numerical model was developed in order to simulate two-phase fluid flow in a single fracture. In the model, variation of viscosity with pressure and that of relative permeability with water saturation can be treated. For the numerical solution, IMPES method was used, from which the pressure and the saturation of water and gas were computed one by one. Seven cases of model test using parallel plates for a single fracture were performed in order to obtain the characteristic equation of relative permeability which would be used in the numerical model. it was difficult to match the characteristic curves of relative permeability from the model tests with the existing emperical equations, consequently a logistic equation was proposed. As the equation is composed of the parameters involving aperture size, it can be applied to any fracture.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5045-5050
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• 2015

As modern houses are constructed with high-density and high-insulation, there is benefit to reduce energy consumption, but there are many side effects raised from polluted air. To solve the problem, a ventilation system is used to improve a indoor air quality. In this study, we tested the parallel flow type heat exchanger used in a heat exchanger of an automotive air conditioner. And we experimentally estimate ventilation performance of HRV(heat recovery ventilator) with heat-pipe according to working fluid filling quantity and ventilation. The working fluid was R22, which was filled from 40 to 60 (%vol.) by 10(%vol.). Ventilation based on the front velocity was measured from 0.3 m/s to 1.5 m/s by 0.3 m/s intervals. Refrigerant filling quantity with the highest efficiency was found to depend on the ventilation. From this study the optimal refrigerant filling quantity in accordance with the ventilation of the detachable heat pipes was found experimentally.