• 설비공학논문집
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• 제18권12호
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• pp.955-963
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• 2006

Nucleate pool boiling heat transfer coefficients (HTCs) were measured with one nonazeotropic mixture of Propane/Isobutane and two azeotropic mixtures of HFC134a/Isobutane and Propane/HFC134a. All data were taken at the liquid pool temperature of $7^{\circ}C$ on a horizontal plain tube with heat fluxes of $10kW/m^2\;to\;80kW/m^2$ with an interval of $10kW/m^2$ in the decreasing order of heat flux. The measurements were made through electrical heating by a cartridge heater. The nonazeotropic mixture of Propane/Isobutane showed a reduction of HTCs as much as 41% from the ideal values. The azeotropic mixtures of HFC134a/Isobutane and Propane/HFC134a showed a reduction of HTCs as much as 44% from the ideal values at compositions other than azeotropic compositions. At azeotropic compositions, however, the HTCs were even higher than the ideal values due to the increase in the vapor pressure. For all mixtures, the reduction in heat transfer was greater with a larger gliding temperature difference. Stephan and $K{\ddot{o}}rner's$ and Jung et al's correlations predicted the HTCs of mixtures with a mean deviation of 11%. The largest mean deviation occurred at the azeotropic compositions of HFC134a/Isobutane and Propane/HFC134a.

• 설비공학논문집
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• 제18권11호
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• pp.859-866
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• 2006

This paper presents the vapor-liquid equilibrium (VLE) data measured for carbon dioxide and propane mixtures. Their mixtures were considered as promising alternative refrigerants due to good thermophysical properties and negligible environmental impact. The isothermal VLE data were measured at eight temperatures ranging from 253.15 to 323.15 K in the circulation type equipment with a view cell. The binary system was found to be a zeotropic mixture in the tested temperature range and could be correlated with sufficient accuracy by using the Peng-Robinson equation of state (PR EoS) with the van der Waals one fluid mixing rule. A comparison with published experimental VLE data has been carried out by means of the PR equation of state. In addition, the phase behaviors of carbon dioxide and propane mixtures were analyzed based on the measured VLE data.

• 한국가스학회지
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• 제1권1호
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• pp.106-112
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• 1997

본 연구는 직류 저항회로의 개폐불꽃에 의한 폭발성 가스의 점화한계를 실험적으로 고찰하였다. 실험은 IEC형 불꽃점화 시험장치의 폭발용기에 폭발성 가스(메탄-공기 프로판-공기, 에틸렌-공기, 수소-공기)를 각각 넣고 텅스텐 전극과 카드뮴 전극사이에서 발생하는 3,200회의 개폐불꽃에 의한 점화유무를 확인하므로서 점화한계를 구하였다. 또한 실험장치의 점화감도교정을 실험한 후에 실시하므로서 실험의 정확성을 기하였다. 실험결과 최소 점화 전류값을 갖는 최소점화한계농도는 메탄-공기 8.3 [$Vol\%$], 프로판-공기 5.25[$Vol\%$], 에틸렌-공기 7.8[$Vol\%$], 수소-공기 21[$Vol\%$]로서 기존의 실험결과와 유사한 결과를 나타내었다. 또한 최소점화한계농도에서 전압과 최소점화잔류와의 관계를 구한 결과 최소점화한계는 메탄, 프로판, 에틸렌, 수소가스의 순서로 낮아졌고 점화전류의 크기는 전원전압의 크기와 반비례하고, 전극의 과열현상으로 인하여 전압 약 20(V)이하에서는 최소점화전류가 2(A)를 넘으면서 심화한계곡선이 급격히 상승한다는 것 등을 알 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.294-299
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• 2012

연소기 내의 연소반응 촉진 및 연소불안정성 해결의 단초를 제공하기 위해, 정상초음파가 개재된 프로판/공기 예혼합화염의 구조거동을 고찰하는 연구를 수행하였다. 화염대의 구조 변이를 가시화하기 위해 슐리렌 기법을 이용하였으며, 당량비에 따른 화염선단의 형상 및 화염 전파속도의 변화를 확인할 수 있었다. 정상초음파는 화염선단을 찌그러뜨렸고, 난류 화염으로의 천이를 가속시켰다.

• 한국연소학회지
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• 제10권2호
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• pp.35-41
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• 2005

Behaviors of lean premixed flame of propane/air and methane/air flame anchored by a pilot flame in a tube were investigated experimentally varying the mean velocity from 10 to 140 cm/s and the equivalence ratio from 0.45 to 0.8. Behaviors of both flames are divided into five regions of stable, flash-back, tail-out, flickering and vibrating. General characteristics of each region and Le number effect are investigated. Two main instabilities, flickering and vibration, are both unstable but the instability mechanism, the frequency and the amplitude of pressure fluctuation are different. In the edge of the vibrating region, pressure fluctuation repeats generation and extinction. Repeated growth and decrease of the amplitude of pressure fluctuation are explained by Rayleigh#s index.

• International Journal of Automotive Technology
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• 제6권2호
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• pp.79-85
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• 2005

This work is to investigate the surface heat flux and combustion characteristics of premixed propane mixture in a constant volume chamber. The experiment of heat flux and combustion characteristics of premixed propane mixture are performed with various equivalence ratio and initial pressure conditions. Based on the experimental results, it is found that the maximum instantaneous temperature is increased with the increase of initial pressure in the chamber. There are significant differences in the burning velocity of premixed propane mixture at different measuring points in the constant volume combustion chamber. A]so, the trends of temperature difference at each measuring points are similar to the burning velocity in the combustion chamber. It is concluded that the total heat loss during the combustion period is affected by the equivalence ratio and the initial condition of fuel-air mixture.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.26-31
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• 2006

Flickering behaviors of lean premixed flame of propane/air and methane/air flame anchored by a pilot flame in a tube were investigated. Unsteady behaviors of the flame were monitored by a high speed ICCD camera and the flickering frequency was defined as the number of flame curvatures passing a fixed spatial point in a second. Unlike previous studies in which flames are in open condition so that the flickering mechanism is an unstable interaction of hot buoyant products with the ambient air, flames in this study are surrounded by a tube which means they are not open to ambient air, so that there is no interaction between hot buoyant products and ambient air. Despite the fact, there exists flickering phenomena and the flickering frequency ranges from 10 Hz to 50 Hz which is wider compared to previous studies. We relate the flickering mechanism to flame-generated vorticity and analytic solution for locally approximated flow is used. As a result, the relationship between flickering wavelength and dimensionless vorticity is acquired and the cause of higher range of flickering frequency is explained.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.1-11
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• 1997

The soot and OH radical distributions have been experimentally studied in ethylene and propane laminar diffusion flames. The integrated soot volume fraction was measured along the centerline of a flame using a laser light extinction method. Planar laser light scattering and PLIF techniques are employed for the soot and OH radical distribution measurements utilizing Nd:YAG laser and OPO, FDO system. The concentration of OH radical is rapidly decreased at the edge of sooting region, which implies the importance of OH radical species on the soot oxidation process. For ethylene flames, the addition of air in fuel moves the OH radical distribution towards the center line of a flame at the soot oxidation region, while the concentration of OH radical remains relatively high at the soot formation region. The interaction between soot particles and OH radicals becomes more active with fuel-air at the soot oxidation region. For propane flames, however, any indication of the increased interaction between soot particles and OH radicals with fuel-air was not noticed.

• 한국가스학회지
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• 제11권4호
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• pp.35-40
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• 2007

본 연구는 마이크로핀관에서 이소부탄과 프로판의 증발 열전달 특성에 대해 실험적으로 조사하였다. 시험부는 외경 12.70 mm이고, 높이가 0.25 mm인 75개 핀이 원주방향으로 삽입되어 있다. 실험결과, 탄화수소계 냉매의 평균 열전달계수는 프레온계 냉매인 HCFC22보다 높을 것으로 나타났고, 높은 질랑유속에서는 이소부탄 > 프로판 순으로 나타났다. 마이크로핀관에서 증발 열전달 계수는 평활관에 비해 약 $80{\sim}100%$ 정도가 향상되었다. 이러한 본 연구 결과로부터 탄화수소계 냉매를 냉동 공조 시스템의 냉매로 사용하여 열교환장치를 설계할 경우에는 유리하리라 생각된다.

• 열처리공학회지
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• 제4권4호
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• pp.53-60
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• 1991

This study has been performed to investigate into the internal oxidation characteristics of low carbon steel with respect to the added amount of air in nitrogen-propane atmosphere after gas carburizing for various times at $930^{\circ}C$. The results obtained from the experiment are as follows ; (1) Optical micrographs have shown that the internal oxidation is unlikely to occur in the gas atmosphere without air and that oxidized zone in the outer surface layer is formed in the gas atmosphere with air revealing that the depth of oxidized zone increases with increasing the added amount of air. (2) The formation of internally oxidized zone in the outer surface layer has been found to be inhibited as Ni content increases, i. e, the amount of alloying element increases. (3) The depth of oxidation has been measured to increase with almost parabolically gas carburizing time of up to 6 hours.