• Journal of Korean Society for Atmospheric Environment
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• 제16권E2호
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• pp.69-77
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• 2000

Measurements of non-methane hydrocarbons (NMHC) were carried out in the Sangdo tunnel and on a nearby roadway in Seoul during the during the periods of heavy(low speed with ∼20km h(sup)-1) and light(high speed with ∼60kmh(sup)-1) traffic in February 2000. In the tunnel, the total NMHC levels during the heavy traffic period were higher than those during the light traffic period by a factor of 2. This was due to the increase of emissions at the low vehicle speed period and the higher dilution effect derived from faster flow of tunnel air at the high vehicle speed period. The average total NMHC concentration in the tunnel was 1.7 times as high as that on the roadway. The species with the highest concentration in the tunnel was ethylene(50.1 ppb), followed by n-butane(34.1 ppb) and propane (21.9 ppb). The concentration ranking in the tunnel was generally in good agreement with that on the roadway, suggesting that the NMHC compositions in the tunnel and on the nearby roadway were primarily determined by vehicle exhausts. However, the NMHC compositions in the Sangdo tunnel do not agree well with other foreign study results, reflecting that the characteristics of vehicle exhausts of Seoul is different from those of other cities. The most prominent difference between this study and other studies is the high mass fractions of butanes and propane. It was be attributed to the wide use of butane-fueled vehicles.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.249-255
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• 2005

Flow condensation heat transfer coefficients(HTCs) of R22, R4IO, Propane(R290) were measured inside a horizontal 9 hole aluminum multi-channel flat tube. The main test section in the refrigerant loop was made of a 0.53 m long multi-channel flat tube of hydraulic diameter of 1.4 mm. Refrigerant was cooled by passing cold water through an annulus surrounding the test section. Data were obtained in qualities of 0.1 ${\sim}$ 0.9 at mass flux of $200{\sim}400$ $kg/m^2s$ and heat flux of $7.3{\sim}7.7$ $kW/m^2$ at the saturation temperature of $4^{\circ}C$. All popular heat transfer correlations in single-phase subcooled liquid flow and flow condensation originally developed for large single tubes predicted the present data of the multi channel flat tube within 25% deviation when effective heat transfer area was used in determining experimental data. This suggests that there is little change in flow characteristics and patterns when the tube diameter is reduced down to 1.4 mm diameter range. Hence, a modified correlation based on the present data was proposed which could be applied to small diameter tubes with effective heat transfer area. The correlation showed a mean deviation of less than 20% for all data.

• 한국가스학회지
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• 제16권3호
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• pp.42-47
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• 2012

본 논문에서는 규제 프레온냉매 R22의 대체 자연냉매의 후보인 R290(프로판), R600(부탄), R717(암모니아), R1270(프로필렌)을 작동유체로 사용하는 2단압축 1단팽창 냉동시스템의 성능 특성을 비교하였다. $-20^{\circ}C{\sim}-50^{\circ}C$ 정도의 저온을 얻기 위해 사용되는 2단압축 1단팽창 냉동장치에서의 증발온도, 응축온도, 과열도 및 과냉각도의 변화에 따른 성능계수(COP) 변화를 규명하고자 하였다. 성능특성 규명 결과, 과냉각도 및 중간냉각기에서의 냉매유량 증가에 따라 시스템의 COP는 증가하였으나, 증발온도, 응축온도 및 과열도가 증가할수록 COP는 저하되는 결과를 나타내었다. 또한, 자연냉매를 사용하는 2단압축 1단팽창 냉동시스템의 COP는 규제 프레온냉매 R22를 사용하는 경우보다 높기 때문에 자연냉매를 사용하고자 하는 냉동시스템의 안전성이 확보되면 충분히 대체 냉매로서의 경쟁력이 있을 것으로 판단되었다.

• 한국가스학회지
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• 제13권6호
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• pp.44-48
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• 2009

본 연구에서는 천연가스 액화 플랜트 산업에서의 핵심 기술인 액화공정 개발을 위해 두 가지 2단 압축 방식의 액화 사이클의 성능을 시뮬레이션 하였다. Process1은 케스케이드 액화공정을 기초로 하여 프로판, 에틸렌, 메탄 사이클 모두 인터쿨러가 적용된 것이다. Process 2는 위의 공정에 메탄과 에틸렌 사이클 사이에 액-가스 열교환기를 적용하였고, Process 3은 위의 공정에 에틸렌과 프로판 사이클 사이에 액-가스 열교환기를 추가로 적용하였으며, 인터쿨러를 적용한 케스케이드 공정과 성능을 비교하였다. Process 2의 COP는 Process 1보다 14.0%정도 높게 나타났고, LNG 단위 생산량 당 소비 동력은 11.5% 정도 낮게 나타났다.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.297-303
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• 2002

The purpose of study is obtaining low-emission and high-efficiency in LPi engine with hydrogen enrichment. The test engine was named variable compression ratio single cylinder engine (VACRE). The fuel supply system provides LPG/hydrogen mixtures based on same heating value. A varied sensors such as crank shaft position sensor (CPS) and hall sensor supplies spark timing data to ignition controller. Displacement of VACRE is $1858.2cm^3$. VACRE was runned 1400rpm with compression ratio 8. Spark timing was set MBT without knocking. Relative air-fuel ratio($\lambda$) of this work was varied between 0,8 and 1.5.

• Macromolecular Research
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• 제10권2호
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• pp.80-84
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• 2002

Silver species other than the silver ion were formed by UV irradiation on polymer electrolyte membranes containing silver salts and their effect on complexation behavior between the silver and olefin was investigated through the separation performance of olefin/paraffin mixtures. The ideal propylene/propane separation factor reached 350 and the separation coefficient was ca.15 due to the high loading amount of silver ions into poly(2-ethyl-2-oxazoline) (POZ) without UV irradiation. On UV irradiation either in air or under nitrogen, the silver-POZ membranes became yellow-brown initially due to the formation of colloidal silver particles, and finally black and metal-like luster. Even when Ag$^{+}$ was converted, to some extent, to Ag$^{\circ}$ by UV irradiation in air at the early stage, the separation coefficient of olefin/paraffin mixtures was maintained. This suggests that silver species other than the silver ion is active for olefin carrier for facilitated transport. Meanwhile the steady decrease of the separation coefficient was observed in the silver/POZ membranes irradiated under $N_2$. It is suggested that the reduction of silver ions in POZ goes through a different photoreduction mechanism with UV irradiation depending on the environment.t.

• Journal of Advanced Marine Engineering and Technology
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• 제28권5호
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• pp.754-761
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• 2004

In this paper, evaporating heat transfer characteristics in the refrigeration and air-conditioning facilities were studied using the environmentally friendly refrigerants R-1270 (Propylene). R-290 (Propane). R-600a (Iso-butane) and HCFC refrigerant R-22 The test tube was surrounded by an annulus with water flowing counter to the refrigerant. The tube is copper. with an outside diameter of 12.7mm and the wall thickness of 1.315mm. The test results showed that the local evaporating heat transfer coefficients of hydrocarbon refrigerants were superior to that of R-22 and the maximum increasing rate of heat transfer coefficient was found in R-1270. The average evaporating heat transfer coefficient increased with the increase of the mass velocity and it showed the higher values in hydrocarbon refrigerants than R-22 Comparing the heat transfer coefficient of experimental results with that of other correlations. the presented results had agood agreement with the Kandlikar's correlation. This results form the investigation can be used in the design of heat transfer exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.

• 대한기계학회논문집B
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• 제26권1호
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• pp.125-132
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• 2002

An experimental study on the characteristics of stability of propane turbulent nonpremixed jet flames discharged normal to air free-streams with uniform velocity profile is conducted. Experimental observations are focused on the flame shape, the stability considering two kinds of flame, lift-off distance, and the flame length according to velocity ratio. In order to investigate the mixing structure of the flame base at the lower limit, we employ the RMS technique and measure the species concentration by a gas chromatography. In the results of the stability curve and lifted flame, it is fecund that the dependency of nozzle diameter is closely related to the large-scale vortical structure representing counter-rotating vortices pair. Also, the detailed discussion on the phenomenon of blowout due to this large vortical motion, is provided.

• 대한기계학회논문집
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• 제13권3호
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• pp.508-516
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• 1989

본 연구는 석탄의 맥동연소과정을 비맥동연소와 빅교실험을 하여 연소특성 을 가시적으로 관찰하고 연소율 등의 연소특성을 구하며 고체연료의 맥동연소과정을 밝히고 맥동연소기 개발의 기초자료를 얻는데 목적을 두었다.

• 오토저널
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• 제7권2호
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• pp.55-63
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• 1985

This study is focused on deposition process leading to inefficiency and hot corrosion in fossil fuel-fired furnaces and engines. An improved understanding of the coupled thermodynamics, kinetics, and transport processes governing the deposition rate of inorganic oxides and salts from hot gases containing these compounds can suggest more efficient test strategies and control measures. Accordingly, an optical re-evaporation method for accurately measuring the growth rate of deposits under laboratory burner conditions has been developed. To demonstrate the technique and provide data suitable for theoretical model development, a deliberately simple chemical system and target geometry are used. Potassium sulfate(K$_{2}$SO$_{4}$)is introduced into a premixed propane-air flat flame at atmospheric pressure. The growth rate of $K_{2}$SO$_{4}$ on an electrically heated Pt ribbon is measured by re-evaporation technique.