• Journal of the KSME
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• v.50 no.9
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• pp.34-38
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• 2010

$CO_2$ 포집기술은 크게 연소 후 포집(Post-Combustion Capture), 연소 중 포집기술인 순산소 연소(Oxy-Fuel Combustion) 및 연소 전 포집(Pre-Combustion)으로 구분되며, 이 글에서는 기존의 공기연소 대신에 산소만으로 연소하여 배가스 중의 수분을 응축 제거함으로써 $CO_2$를 포집하는 순산소 기술의 국내 외 개발현황 등을 소개한다.

• Analytical Science and Technology
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• v.20 no.5
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• pp.361-369
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• 2007

Uncomfortable odor emitted from air conditioning system is the main cause of indoor air quality deterioration. To solve evaporator odor problems, odor active compounds, have to be identified then the quality of the product can be improved its quality. Because evaporator odor in exhaust gas has low odor intensity and discontinuity, it is very difficult to collect and analyze sample. In this study through the identification of odor compounds in condensed water, the evaluation of the eraporator was tested. Odor compounds were extracted from water by headspace-solid-phase microextraction (HS-SPME) method. The single odor was separated by GC/FID/Olfactometry (GC/FID/O) and odor active compounds were identified by GC/AED and GC/MS. Compared to air sample, result of sensory evaluation and the single odor compound appeared similarly. It was identified that odor active compounds have functional group containing oxygen such as alcohols and acids. Evaluation method of odor active compounds using condensed water in evaporator appeared effective on the side of simplicity of collection, low expanse and rapid analysis.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1874-1879
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• 2008

It is not easy to detect nano-sized airborne particles (< 100 nm in diameter) in air. Therefore, the condensation of the nanoparticles alongside of the size-classification is needed for their detection. This paper proposes a hybrid (aerodynamic+electrical) particle classification and condensation device using a micro virtual impactor (${\mu}VI$). The ${\mu}VI$ can classify the nanoparticles according to their size and condense the number concentration of nanoparticles interested. Firstly, the classification efficiency of the ${\mu}VI$ was measured for the particles, polystyrene latex (PSL), ranging from 80 to 250 nm in diameter. Secondly, the nanoparticles, NaCl of 50 nm in diameter, were condensed by 4 times higher. In consequence, the output signal was amplified by 4 times (before condensation: 4 fA, after condensation: 16 fA). It is expected that the proposed device will facilitate the detection of nanoparticles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.12
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• pp.858-866
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• 2012

A numerical study was performed to predict the performance of a fin-and-tube condenser. A condenser model was developed and verified by comparing the simulation results with experimental data for a R410A condenser in a residential air-conditioning system. The prediction error was 0.07% and -5.77% for the condenser capacity and pressure drop, respectively. In simulation results, the capacity and pressure drop of the condenser with even air velocity distribution were 0.67% and 12.93% higher than those with uneven distribution of air velocity. It was predicted by the model that the refrigerant distribution at the condenser inlet to the two first passes was not significantly influenced by the air distribution. The simulation results presented that the 1.49% of capacity and 64.6% of pressure drop were reduced by replacing helical microfin tubes with smooth tubes for the condenser.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.293-303
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• 1977

Cellulosic organic solid wastes such as bark and sawdust, and filter papers as a pure cellulose were pyrolyzed at $300^{\circ}C$ under nitrogen current and mixed current of nitrogen and air. Amounts of condensates collected in air, water, and dry ice-acetone cooling traps, noncondensable gases, and carbonized residues were surveyed. The components of volatile liquids condensed in dry ice-acetone trap were separated by means of gas chromatograph and identified by retention times and syringe reactions. Pyrolysis under nitrogen current produced 13.4∼29.6${\%}$ of tar, 0.01∼0.12${\%}$ of aqueous liquids, 0.24∼1.43${\%}$ of volatile liquids, 9.84∼42.41${\%}$ of noncondensable gases, and 44.0∼65.81${\%}$ of carbonized residues. Pyrolysis under mixed current decreased tar and condensable liquids, but increased noncondensable gases.Volatile liquids collected under nitrogen current separated into the same 19 components by Porapak Q column regardless of the materials and only difference among materials was relative amounts of components. Volatile liquids collected under mixed current separated into six components and mainly lower molecular weight compounds such as methanol and formaldehyde were produced. According to the retention times and syringe reactions, methanol, formaldehyde, acetone, acetaldehyde, acetic acid, and three other compounds presumably containing hydroxyl group in the molecular structure were identified out of 19 compounds.

• Journal of Energy Engineering
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• v.15 no.4 s.48
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• pp.243-249
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• 2006

An experimental study on the refrigerant-side pressure drop of slit fin an tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and Rl34a. Experiments were carried out under the conditions of inlet refrigerant temperature of $60^{\circ}C$ and mass fluxes varying from $150\;to\;250\;kg/m^{2}s$ for R22 and Rl34a. The inlet air conditions are dry bulb temperature of $35^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R134a was $22{\sim}22.6%$ higher than R22 for the degree of subcooling $5^{\circ}C$ For the mass fluxes of $200{\sim}250\;kg/m^{2}s$, the deviation between the experimental and predicted values for the pressure drop was less than ${\pm}20%$ for R22 and Rl34a.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.91-98
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• 2011

연료전지 차랑용에 있어서 공기 가습 및 감습의 중요성은 매우 크다. 특히 PEM(Proton Exchange Membrane)연료전지에서 수분평형은 총괄시스템성능에 큰 영향을 미치는 요소인데, 이에 관한 중요한 연구가 지금까지 광범위하게 수행되고 있다. 또한 차량과 같이 동적부하 연료전지를 활용하는 분야에 있어서, 전류의 흐름은 차량용 파워 부하에 크게 영향을 받는다. 따라서 전기적 흐름이 발생하면, 이에 따라 수분이 발생하게 되는데, 이러한 응축 수분은 예측이 되며, 수관리 시스템에서 이를 중요한 제어 기준으로 활용한다. 그러므로 적절한 제어방법을 선택하면 유입공기의 온도와 습도의 최적값을 얻을 수 있다. 따라서, 본 논문에서는 PEM 연료전지의 수관리를 위하여 수분전달 모델과 유전알고리즘(genetic algorithm)을 사용하는 제어방법에 초점을 두고 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.463-469
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• 1990

A rapid expansion of moist air of condensible gas through a supersonic nozzle gives rise to condensation of nonequilibrium and equilibrium processes. Because most of the effects of condensation on the flow are caused by process of nonequilibrium condensation, it is very important to know the onset. condition of nonequilibrium condensation. In the present study, the relation between the initial relative stagnation humidity and the onset Mach number, for the case of the similarity law suggested by Zierep and Lin. Furthermore, the present theoretical result number is compared with the experimental, numerical and other results.

• Journal of the KSME
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• v.30 no.4
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• pp.310-321
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• 1990

기체, 액체 고체상(相)이 섞여서 함께 흐르는 유동을 다상유동(multiphase flow)이라고 하며, 그 중 2개의 상이 섞여서 흐르는 경우를 2상유동(two-phase flow)이라고 일컫는다. 다상유동의 현상은 일상적인 생활에서도 많이 접하며(예컨대, 눈, 비가 내리는 현상, 안개, 황사, 스모그 현상 등) 특히 열전달과 관련하여 비등 및 응축을 수반하기도 한다. 특히 기계공학적 시스템에의 응 용측면에서는 다상유동의 전문지식이 증발기, 응축기 등 각종 열교환기기의 설계에 적용되므로 본 해설에서는 기체-액체(gas-liquid) 2상유동으로 그 내용을 한정하기로 한다. 2상(two-phase) 유동은 동일한 화학적 성분을 가진 물질이 서로 다른 상을 유지하면서 공존하여 흐른다는 점에서 2개의 다른 화학성분으로 구성된 2성분(two-component) 유동(예컨대 공기-물의 혼합유동)과는 엄밀하게는 다르나, 두 유동은 제반 형상이 유사하고, 해석 및 실험방법면에서도 많은 유사성이 있어서 총괄적으로 두 유동을 모두 2상유동이라고 칭하고 있다(1). 본 해설에서는 이러한 기체 -액체 2상유동분야에서 다루는 연구내용을 개괄적으로 소개하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.4
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• pp.193-198
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• 2014

Heat transfer performance variation of a condenser caused by non-uniform distribution of air flow was investigated using a numerical simulation method. A heat exchanger used for a outdoor unit of a commercial heat pump system and represented by a numerical model was selected. Non-uniform profile of air-velocity was constructed by measuring the air velocity at various locations of the outdoor unit. Simulation was conducted for various refrigerant circuits and air flow conditions. Simulation results show that the heat transfer capacity was reduced depending on the air-flow rate and the refrigerant circuit configuration. It is also shown that the capacity reduction rate is increased as the average air velocity decreases.