• 한국산업융합학회 논문집
• /
• 제8권4호
• /
• pp.191-196
• /
• 2005

This study was carried out to investigate the heat storage/release characteristics of the thermochemical reaction of the calcined dolomite with the packed bed shape experimental apparatus for development of chemical heat pump system. In the present study, it was found that MgO of the calcined dolomite was not hydrated during the hydration process under the experimental conditions. Therefore, the MgO of the calcined dolomite can be regard as an inert material. As a result, it was found that all of CaO packed kept the reaction temperature of about $510^{\circ}C$ through the entire part of the bed. The dehydration reaction was incurred first at the wall side area as the supplied heat was transferred through the wall side into the packed bed. As a result of the temperature and concentration spread, the reaction was completed at the wall side progressed into the center.

• 한국화재소방학회논문지
• /
• 제24권3호
• /
• pp.39-44
• /
• 2010

현재 열방출률을 측정하는 데 사용되고 있는 콘칼로리미터 법은 일정한 복사도 값을 가지고 실험한다. 하지만, 실물화재 시 가연물은 연소할 때 동일하지 않은 열선속을 방출한다. 본 연구에서는 일정 크기를 갖는 실내를 대상으로 FDS를 사용하여 실내 열선속 변화에 따른 연소특성을 분석하여 실내화재 시 온도 변화를 계산하여, 콘칼로리미터의 콘 히터에 유동적인 열선속을 적용하여 복사도에 반영하였다. 결과로 화재 성장기(Growth period) 및 감쇠기(Decline period)와 같은 복사도의 변화에 따라 실물화재에 근거한 PMMA의 열방출률을 얻을 수 있었다.

• 대한기계학회논문집B
• /
• 제26권9호
• /
• pp.1284-1291
• /
• 2002

Combustion instabilities are an important concern associated with lean premixed combustion. Laboratory-scale dump combustor was used to understand the underlying mechanisms causing combustion instabilities. Experiments were conducted at atmospheric pressure and sound level meter was used to track the pressure fluctuations inside the combustor. Instability maps and phase-resolved OH chemiluminescence images were obtained at several conditions to investigate the mechanism of combustion instability and relations between pressure wave and heat release rate. It showed that combustion instability was susceptible to occur at higher value of equivalence ratio (>0.6) as the mean velocity was decreased. Instabilities exhibited a longitudinal mode with a dominant frequency of ∼341.8 Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instabilities occurred. Rayleigh index distribution gave a hint about the location where the strong coherence of pressure and heat release existed. These results also give an insight to the control scheme of combustion instabilities. Emission test revealed that NOx emissions were affected by not only equivalence ratio but also combustion instability.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1146-1151
• /
• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel de-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented for typical locations.

• 한국화재소방학회논문지
• /
• 제17권2호
• /
• pp.17-24
• /
• 2003

본 논문은 파스콘 또는 콘크리트 재질의 트로프에 설치되는 전선에 대한 열의 영향과 이들 트로프에 대한 열 방출 정도에 대한 차이점을 이론상으로 접근하고 평가하고자 하였으며, 실제 상황과 근접한 조건으로 컴퓨터 시뮬레이션을 실시함으로서 두 트로프 내의 전선에 대한 열의 영향과 두 트로프의 열 발산정도를 추정하고 그에 대한 타당성을 입증하고자 하였다. 이에 대한 연구 결과 파스콘의 고유 열전도 값과 콘크리트의 고유 열전도 값을 단순 비교하면 콘크리트 제품의 열 방출량이 우수한 것으로 판단할 수 있으나, 실제 설치되는 두 트로프의 실제 두께와 면적 및 세부 구조를 고려하여 연산 및 시뮬레이션을 실시해 본 결과 파스콘 트로프가 콘크리트 트로프 보다 다소 우위에 있는 것으로 평가되었다.

• 한국염색가공학회지
• /
• 제19권1호
• /
• pp.24-30
• /
• 2007

Heat storage/release system in textile is a useful tool to increase energy efficiency and enhance comfortable microclimate of clothing. Phase change materials(PCM) are used in regulating storage and release properties of thermal energy. To investigate the temperature regulating ability of fabrics with PCM microcapsule(PCMMc), Nylon fabrics were coated with PCMMc via wet processing and they were characterized by SEM, DSC and infrared thermal analyzer. Also, water moisture transpiration, water penetration resistance, peel strength and washing durability of the fabrics were assessed. The water vapor permeation and water penetration resistance decreased with increasing PCMMc content. In DSC analysis, it can be seen that the microencapsulated fabric showed both exothermic md endothermic phenomena at specific temperature. Peel strength was decreased with increasing PCMMc content.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
• /
• pp.41-42
• /
• 2006

A study on the combustion characteristics by using Emulsion Fuel in Diesel Engine is performed experimentally. In this paper, the experiments are performed at engine speed 1800rpm, emulsion fuel ratio is 0%, 10%, 20%, and main measured items are specific fuel consumption, pressure, ratio of pressure rise, rate of heat release etc. The obtained conclusions are as follows. 1) Specific fuel consumption increase maximum 19.8% at low load, but is not effected at full load. 2) Ratio of pressure rise and rate of heat release are about the same in the case of 10% and 20% of emulsion fuel ratio. 3) Cylinder Pressure increase 11.7%, ratio of pressure rise increase 60.4% in case of emulsion fuel ratio 20% at full load. 4) Rate of heat release increase 76.9% in case of emulsion fuel ratio 20% at full load.

• International Journal of Automotive Technology
• /
• 제8권1호
• /
• pp.1-7
• /
• 2007

The effect of the di-tertiary butyl peroxide (DTBP) additive on the heat release rate and emissions of a homogeneous charge compression ignition (HCCI) engine fueled with high Research Octane Number (RON) fuels were investigated. The experiments were performed using 0%, 1%, 2%, 3%, and 4% (by volume) DTBP-RON90 blends. The RON90 Fuel was obtained by blending 90% iso-octane with 10% n-heptane. The experimental results show that the operation range was remarkably expanded to lower temperature and lower engine load with the DTBP additive in RON90 fuel. The first ignition phase of HCCI combustion was observed at 850 K and ended at 950 K while the hot ignition occurred at 1125 K for all fuels at different engine working conditions. The chemical reaction scale time decreases with the DTBP addition. As a result, the ignition timing advances, the combustion duration shortens, and heat release rates were increased at overall engine loads. Meanwhile, the unburned hydrocarbon (UHC) and CO emissions decrease sharply with the DTBP addition while the NOx emissions maintain at a lower level.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
• /
• pp.137-140
• /
• 2004

주기적인 와류화염과 열방출 진동의 연관성에 대한 실험적인 연구가 수행되었다. 난류제트화염은 덤프 연소기에서 재순환 되는 뜨거운 생성물에 의해서 안정화되며, 큰 스케일의 주기적 와류가 음파에 의해서 제트화염에 부가되었다. 실제적인 연소기에서의 불안정 현상을 모사하기 위해 가진주파수와 실험변수들을 조절하였다. 본 연구의 목적은 원치 않는 열방출의 진동을 유도시키는 와류-열방출의 연관성을 분석하여, 연소불안정의 능동제어를 위해 사용될 수 있는 알맞은 연료분사 패턴을 조사하는 것이다. 주기적인 패턴을 측정할 수 있는 슐리렌 기법과 CH* chemiluminescence 기법이 사용되었으며, 실험결과는 와류 생성 사이클의 위상에 따라서 서로 비교되었다.

• 한국자동차공학회논문집
• /
• 제17권4호
• /
• pp.126-132
• /
• 2009

Automotive heat exchangers use louver fins for their high efficiency. However, the efficiency can significantly drop for constructional vehicles or heavy equipments due to dust deposited on the louver fins with narrow slits. Thus it is necessary to develop new fins that lead to less fouling, so that a better performance can be achieved after exposure to a dusty environment over long period of time. New wavy fins were considered in the study and numerically analysed to compare with louver fins in the areas of air-side pressure drop, heat release rate, and particulate deposition. In addition, an experiment was done on the pressure drop and the particulate deposition. The results showed that the wavy fins would be a better choice for long-term use due to the excellent dust-proof performance in comparison to louver fins, in spite of the initial inferior performance of heat release.