• 대한기계학회논문집
• /
• 제1권4호
• /
• pp.182-189
• /
• 1977

The propagating flame temperature of the Propane-Air premixture by using 30.$\mu$ and 50.$\mu$ diameter platinum sensing wires, that is, Two Wires Correction Method, Through the constant volume burining inside the 150mm diameter, 30mm height combustion chamber under the circumstances of the atomospheric pressure, and the room temperature was determined. Also the temperature distribution across High Temperature Region, i.e. Flame Front, and the temperature profile behind the flame the front have been obtained.

• 한국실내디자인학회:학술대회논문집
• /
• 한국실내디자인학회 2005년도 춘계학술발표대회 논문집
• /
• pp.267-270
• /
• 2005

The purpose of this study was to make clear the indoor environmental efficiency of front balcony 'in apartment houses during winter. The field measurements of indoor environmental elements were carried out at an ordinary house with an existing front balcony and a house renovated the front balcony into the living room. The measurements in two-subject houses were taken on simultaneously the 20$^{th}$ ${\sim}$ 21$^{th}$ of January 2003. As results, the averages indoor temperature in the ordinary house and the renovated house were same as 23.6${\circ}$C, and the averages globe temperature in two houses were same as 23.7${\circ}$C. But, estimated heating time of the renovated house was longer than that of the ordinary house. The daily ranges of indoor temperature and globe temperature in the renovated house were wider than the ordinary house. The daily ranges of indoor temperature and globe temperature in the renovated house was longer than that of the ordinary house. The uniformity ratio range of daylight in the ordinary house were calculated at 1/3.4${\sim}$1/6.2, but those of the renovated house were 1/6${\sim}$1/16.2. Therefore. it was found that indoor temperature, globe temperature and uniformity ratio of daylight in the ordinary house maintained more constant than the renovated house by green house effect and earning effect of front balcony.

• 한국자동차공학회논문집
• /
• 제9권4호
• /
• pp.1-9
• /
• 2001

The soot yield has been studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effects of pressure, temperature and turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degree intervals in order to observe the soot formation under high pressures. The eight flames converged compress the end gases to a high pressure. The laser schlieren and direct flame photographs for observation field with 10 mm in diameter are taken to examine into the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. The pressure and temperature during soot formation are changed by varying the initial charge pressure and the volume fraction of inert gas compositions, respectively. It is found that the soot yield increases with dropping temperature and rising pressure at constant equivalence ratio, and that the soot yield of turbulent combustion decreases in comparison with that of laminar combustion because the burnt gas temperature increases with the drop of heat loss.

• 융합신호처리학회논문지
• /
• 제22권3호
• /
• pp.116-121
• /
• 2021

에너지를 절약하기 위해 고효율 히트펌프를 개발하기 위한 많은 연구가 이루어지고 있으며, 실외기 코일에 발생하는 서리가 발생하는 현상을 줄이거나 없애기 위한 연구도 동시에 이루어지고 있다. 계절과 관계없이 히트펌프의 실외기에 서리가 발생하지 않는 연구를 진행할 수 있도록 자연 상태와 동일한 조건에서 실험할 수 있는 곡선형 항온챔버를 구축하였다. 이러한 곡선형 항온챔버가 실험 장치로서 타당성을 갖추고 있는지 검증하기 위해 시뮬레이션을 하였다. CFD 조건은 곡선형 항온챔버 내에 위치한 실외기 앞의 직선형 덕트 길이를 덕트 관경의 1배, 5배, 10배, 15배로 하였다. 그 결과 덕트 관경의 10배 길이로 시뮬레이션했을 때 자연 상태와 가장 유사하다는 것을 알게 되었다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권7호
• /
• pp.889-898
• /
• 2003

The soot yield is studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effect of turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degree intervals in order to observe the soot formation under high pressures and high temperatures. The eight flames converged compress the end gases to a high pressure. The laser schlieren and direct flame photographs for observation field with 10 mm in diameter are taken to examine into the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. It is found that the soot yield of turbulent combustion decreases in comparison with that of laminar combustion because the burnt gas temperature increases with the drop of heat loss.

• International Journal of Automotive Technology
• /
• 제7권4호
• /
• pp.391-397
• /
• 2006

The soot yield has been studied by a premixed propane-oxygen-inert gas combustion in a specially designed disk-type constant-volume combustion chamber to investigate the effect of pressure, temperature and turbulence on soot formation. Premixtures are simultaneously ignited by eight spark plugs located on the circumference of chamber at 45 degrees intervals in order to observe the soot formation under high temperature and high pressure. The eight converged flames compress the end gases to a high pressure. The laser schlieren and direct flame photographs with observation area of 10 mm in diameter are taken to examine the behaviors of flame front and gas flow in laminar and turbulent combustion. The soot volume fraction in the chamber center during the final stage of combustion at the highest pressure is measured by the in-situ laser extinction technique and simultaneously the corresponding burnt gas temperature by the two-color pyrometry method. The changes of pressure and temperature during soot formation are controlled by varying the initial charging pressure and the volume fraction of inert gas compositions, respectively. It is found that the soot yield increases with dropping the temperature and raising the pressure at a constant equivalence ratio, and the soot yield in turbulent combustion decreases as compared with that in laminar combustion because the burnt gas temperature increases with the drop of heat loss for laminar combustion.

• 태양에너지
• /
• 제18권2호
• /
• pp.91-104
• /
• 1998

본 연구에서는 냉매 HFC134a를 사용한 배치형 열펌프건조기(Batch type heat pump dryer)에 대하여 수치적 해석을 수행하였다. 즉 냉매의 과열도와 과냉도를 일정하게 유지하고 공기의 질량유량, 공기의 바이패스비(bypass ratio), 압축기의 회전속도, 건조기의 입구건구온도에 따른 건조기의 성능을 분석하였다. SMER에 대하여 수치해와 실험치를 비교한 결과 최대 10%이내에서 잘 일치 하였다. 또한 공기의 질량유량에 대하여 적정공기의 바이패스비가 존재하며, 건조기 입구온도가 $35^{\circ}C$이고, 압축기 회전속도가 1360rpm일 때, 공기질량유량이 0.5kg/s에서는 공기의 바이패스비가 30%, 0.7kg/s에서는 공기의 바이패스비가 40%, 0.9kg/s와 1.1kg/s에서는 공기의 바이패스비가 50%에서 최대의 SMER이 나타다. 그리고 압축기 회전속도가 증가함에 따라 SMER은 감소지만 COP는 증가하고 건조기의 입구건구온도가 증가함에 따라 SMER과 COP는 감소하는 것으로 나타났다.

• 한국식품영양과학회지
• /
• 제21권2호
• /
• pp.213-218
• /
• 1992

식품의 동결중에 생성되는 빙결정의 크기에 미치는 동결조건의 영향을 조사하고 그 관계를 정량적으로 평가함과 아울러 동결조건과 빙결정 분산구조와의 관계를 이론해석에 의해 조사한 결과, 1. 동결이동속도 u는 생성빙결정의 평균경 d$_{p}$와 u .d$_{p}$/D~constant의 관계에 있음을 간단한 차원해석에 의해 예측이 가능하였다. 2. 2% 한천 겔, 5%한천 겔, 20% 젤라틴 겔, 돈육의 순서로 동결점에 도달하는 시간이 빨라지며 동결시간 및 최대빙결품 생성대의 통과시간은 냉매온도와 선형적인 관계를 나타내었다. 3. 대두 단백질 겔중에 생성되는 빙결정의 평균경 d$_{p}$와 동결계면 이동속도 u 는 반비례 관계를 나타내었으며, 이로부터 구해진 u .d$_{p}$의 값은 3.4$\times$$10^{-6}$ $\textrm{cm}^2$/sec로 예측 이론식이 유효한 것으로 사료되었다. 4. 동결보존중의 대두 단백질 겔 내부에 생성된 빙결정의 성장에 미치는 보존온도의 영향을 조사한 결과, 양자가 빙결정의 성장에 미치는 영향은 거의 없는 것으로 나타났다. 5. 동결조건과 동결계면구조와의 사이에 Moving velocity of freezing front= (Mass transfer rate of water at freezing front)$\times$ (Surface area of freezing front) 의 관계를 나타내었다.

• 설비공학논문집
• /
• 제11권4호
• /
• pp.528-536
• /
• 1999

This work studies the effects of transient reflectance on the thermal responses of a metal(gold) thin-film during ultrashort laser heating. The heating process is calculated using the conventional conduction model (parabolic one-step: POS), parabolic two-step model (PTS) with and without variable properties, hyperbolic two-step model (HTS). Results from the HTS model are very similar to those from the PTS model, since the laser heating time in this study is greater than the electron relaxation time. PTS model with variable properties, however, results in totally different temperature profiles compared to those from POS models or calculation with constant properties. Transient reflectances are estimated from electron temperature distributions and based on the linear relationship between the electron temperature and complex dielectric constants. Reflectance of the front surface can be changed with respect to dielectric constants, while those of the rear surface remain unchanged.

• 설비공학논문집
• /
• 제11권1호
• /
• pp.38-47
• /
• 1999

An improved one-dimensional modeling of snow melting was obtained by considering both the effect of heat capacity and the decreasing influence of porosity. Using the improved model, the effects of initial snow temperature, initial snow density and the heat flux on the snow melting were investigated. It is found that the drainage starting time is delayed and the drainage rate becomes smaller with lower initial snow temperature. ResuIts also show that the drainage starts at the same time when an initial snow density is over a certain value. Melting efficiency increases linearly with an increasing initial snow temperature. With increasing the initial density of the snow and the amount of heat supplied, the melting efficiency increases, then converges to a constant value.