• Clean Technology
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• v.9 no.1
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• pp.37-42
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• 2003

Biofiltration was successfully applied to treat a mixture of volatile organic compounds(benzene, xylene) from contaminated air stream. Immobilized Ps. oleovorans biofilter was evaluated for its value in simultaneous removal of benzene and xylene from waste air stream. The variety of operating conditions were tested to evaluate important factors such as space velocity, pH, water content, etc.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.37-44
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• 2007

A nickel foam, one of metal foams was seleced as a catalyst support instead of conventional ceramic materials. $Al_2O_3$ was coated on the surface of nickel foam to increase the surface area. $Al_2O_3$ coating process was based on sol-gel process. SEM image was obtained and $Al_2O_3$ coverage was confirmed. Combustion experiments were carried out using SUS combustor and $H_2$/air mixture. Temperatures were measured with different equivalence ratios and $H_2$ flow rates. $H_2$ conversion rates were calculated by the analysis of product gas using gas chromatography. Catalytic combustion of $H_2$ was complete and stable with Pt/$Al_2O_3$ coated nickel foam and influences of water vapor were confirmed during the beginning of combustion.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.413-420
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• 2011

Thermodynamic cycles using binary mixtures as working fluids offer a high potential for utilization of low-temperature heat sources. This paper presents a thermodynamic performance analysis of Goswami cycle which was recently suggested to produce power and cooling simultaneously and combines the Rankine cycle and absorption refrigeration cycle by using ammoniawater mixture as working fluid. Effects of the system parameters such as concentration of ammonia and turbine inlet pressure on the system are parametrically investigated. Results show that refrigeration capacity or thermal efficiency has an optimum value with respect to ammonia concentration as well as to turbine inlet pressure.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.468-476
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• 2002

This paper deals with heat and mass transfer characteristics and performance evaluation of a counter flow double-tube condenser for a multi-component refrigerant mixture. The local heat and mass transfer characteristics of ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a are evaluated for a counter flow double-tube condenser cooled by water. Then, the local values of vapor quality, thermodynamic states at bulk vapor, vapor-liquid interface and bulk liquid, heat flux and condensation mass flux are obtained. The heat exchange performance for ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a on the total pressure drop and the heat transfer characteristics are also compared with those for R404A, R410A, R502, R22, R32, Rl23 and R134a.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.109-117
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• 2009

In this study, thermodynamic performance of R430A is examined both numerically and experimentally in an effort to replace HFC134a used in the refrigeration system of domestic water purifiers. Even though HFC134a is used predominantly in such a system these days, it needs to be phased out in the near future in Europe and most of the developed countries due to its high global warming potential. To solve this problem, cycle simulation and experimental measurements are carried out with a new refrigerant mixture of 76%R152a124% R600a using actual domestic water purifiers. This mixture is numbered and listed as R430A by ASHRAE recently. Test results show that the system performance with R430A is greatly influenced by the amount of charge due to the small internal volume of the refrigeration system of the domestic water purifiers. With the optimum amount of charge of 21 to 22 grams, about 50% of HFC134a, the energy consumption of R430A is 13.4% lower than that of HFC 134a. The compressor dome and discharge temperatures and condenser center temperature of R430A are very similar to those of HFC134a at the optimum charge. Overall, R430A, a new long term environmentally safe refrigerant, is a good alternative for HFC134a requiring little change in the refrigeration system of the domestic water purifiers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.3
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• pp.194-199
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• 2001

The turbulent flow resistance of water solution with polymer is reduced as compared with that of pure water. This effects is named th drag reduction and offers the significant reduction of the pumping power and the energy consumption. But the intense shear forces and the high temperature experienced by the polymer solution when passing through the pipes cause the degradation a loss of drag reduction effectiveness. Especially, the degradation behavior is found to be strongly dependent on temperature. This mechanical and thermal degradation can be avoided by adding materials such as surfactant to the polymer solution, which enhance the bonding force between molecules. In the present study, Copolymer and SDS were utilized and they were mixed in 10 different mixture ratios, while total concentration was fixed as 100wppm. Degradation of Copolymer-SDS mixture solutions was investigated experimentally in closed loop at the temperature of $10^{\circ}C\; and\; 80^{\circ}C$ with various flow average velocities of 1.5 m/sec, 3.0m/sec, and 4.5m/sec. Degradation characteristics of polymer solution without surfactant show a radical loss of drag reduction effectiveness at high temperature. Degradation alleviation ability of surfactant is especially effective at high temperature. Consequently, this results show that the addition of surfactant to the polymer solution can control unfavorable degradation phenomena for high temperature systems.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.386-390
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• 2016

Water aeration is an effective water treatment process, which involves the injection of air or air-water mixture into water treatment reservoir commonly through pipes. The main purpose of water aeration is to maintain healthy levels of dissolved oxygen (DO), which is the most important water quality factor. The pipes' operating conditions are important for controlling the efficiency and effectiveness of aeration process. Many studies have been conducted on two-phase flows in pipes, however, there are a few studies to deal with small s ale in millimeter. The main objective of this study is to perform 2-dimensional two-phase simulations inside various straight pipes using the computational fluid dynamic (CFD) OpenFOAM (Open source Field Operation And Manipulation) tools to examine the influence of flow patterns on bubble size, which is closely related to DO concentration in a water body. The both flow regimes, laminar and turbulence, have been considered in this study. For turbulence, Reynolds-averaged Navier-Stokes (RANS) has been applied. The coalescence and breakage of bubbles caused by random collisions and turbulent eddies, respectively, are considered in this research. Sauter mean bubble diameter and water velocity are compared against experimental data. The simulation results are in good agreement with the experimental measurements.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.251-255
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• 2002

Eutrophic matters accumulated on the bottom of sea, river and lake cause red tide phenomenon in ocean and outbreak green algae in river and lake. Systems are developed to remove the noxious deposit. But the existing systems remove not only the eutrophic matters but also natural materials, sand, pebbles etc. that should remain at the bottom. This paper describes a new system that can safely, and economically take away the noxious deposit in underwater. High pressure water jet is used to induce vortices in the triangular suction section, and air-lifting pump to lift up the deposit. The mixture of the water and deposit is filtered through the drum filters. An under camera shows the under water situation along the moving direction of the system that is controlled by a remote operator. This remote controlled moving system obliterate the necessity of the diver that usually costs high. The experimental results show the effectiveness of the suggested system.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.191-198
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• 1998

In this study, the effects of water vapor in inlet air, spark advance and fuel type in the spark ignition engine were investigated through the experiments of combustion and flame arriving pattern analysis using ionization probe. The results of flame propagation experiment using ionization probe show that the flame which ignited from spark plug located at the center of the combustion chamber propagated faster in exhaust side than in intake side due to the mixture flow motion inducted into combustion chamber from intake tumble port at all conditions. And as the partial vapor pressure increased, the flame propagation became slower in all direction. Especially effects were greater for intake side than the exhaust side.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.6
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• pp.518-525
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• 2006

The present experiments have been performed for obtaining the melting heat transfer characteristics of micro-encapsulated solid-liquid phase-change material and water mixture slurry flow in a circular tube heated with constant wall heat flux. The phase change material having a low melting point was selected for a domestic cooling system in the present study. The governing parameters were found to be latent heat material concentration, heat flux, and the slurry velocity. The experimental results revealed that the increase of tube wall temperature of latent microcapsule slurry was lower than that of water caused by the heat absorption of fusion.