• 한국자동차공학회논문집
• /
• 제25권3호
• /
• pp.336-343
• /
• 2017

Intake air conditions, such as air temperature, pressure, and humidity, are very important parameters that influence engine performance including combustion and emissions characteristics. The purpose of this study is to investigate the effects of intake air temperature on combustion and exhaust emissions characteristics in a single cylinder diesel engine. In this experiment, an air cooler and a heater were installed on the intake air line and a gas flow controller was installed to maintain the flow rate. It was found that intake air temperature induced the evaporation characteristics of the fuel, and it affects the maximum in-cylinder pressure, IMEP(indicated mean effective pressure), and fuel consumption. As the temperature of intake air decreases, the fuel evaporation characteristics deteriorate even as the fuel temperature has reached the auto-ignition temperature, so that ignition delay is prolonged and the maximum pressure of cylinder is also reduced. Based on the increase in intake air temperature, nitrogen oxides(NOx) increased. In addition, the carbon monoxide(CO) and unburned hydrocarbons(UHC) increased due to incomplete fuel combustion at low intake air temperatures.

• 에너지공학
• /
• 제24권3호
• /
• pp.55-60
• /
• 2015

Recent engine development has focused mainly on the improvement of engine efficiency and output emissions. The improvements in efficiency are being made by friction reduction, combustion improvement and thermodynamic cycle modification. Computer simulation has been developed to predict the performance of a spark ignition engine. The effects of various cylinder pressure, heat release, flame temperature, unburned gas temperature, flame properties, laminar burning velocity, turbulence burning velocity, etc. were simulated. The simulation and analysis show several meaningful results. The objective of the present study is to develop a combustion model for a spark ignition engine running with isooctane as a fuel and predicting its behavior.

• 대한기계학회논문집
• /
• 제19권8호
• /
• pp.1989-1998
• /
• 1995

Characteristics of the flame propagation for normal and abnormal combustion in hydrogen premixture in a cylindrical constant-volume combustion chamber are studied numerically. A detailed hydrogen oxidation kinetic mechanism, mixture transport properties and a model describing spark ignition process are used. The calculated pressure-time history of the stable deflagration wave propagation agrees well with the experiment. The ignition of the premixture in the unburned gas, initiated by the hot spot, causes a transition from deflagration to detonation under some initial temperature and pressure. Under the initial conditions with high temperature and pressure, excessive ignition energy initiates a strong blast wave and a detonation wave that follows. The chemical reaction in the detonation wave is much more vigorous than that in the deflagration wave and the peak pressure in the detonation wave is much higher than the equilibrium value.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2019년도 춘계학술대회
• /
• pp.462-463
• /
• 2019

본 논문에서 연구하는 방안은 석탄 화력발전소의 옥내 저탄장 석탄의 자연발화를 예방하기 위한 방법으로, 석탄의 자연발화를 사전에 감지하여 발화 장소의 위치를 알람서비스를 할 수 있게 하기 위한 위치 확인 방안으로 사물인터넷기술(IoT)과 센서기술을 접목하여 석탄의 저장소의 온도를 24시간 모니터링을 통해 전체 저장된 석탄의 온도변화를 감지하는 것이다.

• 한국안전학회지
• /
• 제31권4호
• /
• pp.1-8
• /
• 2016

The behavior of backdraft in the compartment with different ignition locations and times was numerically investigated. The Fire Dynamics Simulator (FDS) v5.5.3 with a model-free simulation option was used in the numerical simulation of backdraft. The ignition source was located near the inside wall, at the compartment center and near the window opening, respectively. The ignition was started at the instance when the fresh air reached the ignition location or when a sufficient time passed compare to the instance of the arriving of the fresh air to the ignition location. As a result, for the ignition source was located near the inside wall, a strong fire ball was observed at once and the result was similar to the previous experimental result. For the ignition source was located at the center of the compartment, a strong fire ball was occurred and two strong fire balls were observed consecutively for the ignition time was delayed. For the ignition source was located near the window opening and longer time was given for the ignition compare the duration of the fresh air arriving to the ignition location, the rapid temperature variation was not observed because there was no flame. However, for the ignition was started at the instance when the fresh air reached the ignition location, the ignition could be initiated and a intensive fire ball was observed. The pressure measured at the upper inside part of the window opening provided a similar trend with the previous experimental result of compartment backdraft.

• 한국화재소방학회논문지
• /
• 제15권2호
• /
• pp.1-5
• /
• 2001

전분 분말의 온도에 따른 열적 안정성을 조사하기 위하여 시차주사열량계(DSC, Differential Scanning Calorimeter) 빛 열중량 분석기(TGA, Thermogravimetric Analysis)를 이용하여 온도에 따른 발열개시 온도, 발열량 등을 조사하였으며, 자연발화 시험기를 이용하여 시료량에 따른 전분 분말의 연소특성을 시간에 따른 온도의 변화를 측정하여 연소개시시간 및 연소시 상승하는 온도를 측정함과 동시에 육안으로 연소특성을 조사하고자 하였다. 한편 자연발화 시험기 내부의 공기흐름에 따른 연소특성을 조사하기 위하여 송풍과 무풍 상태에서의 연소특성을 조사하고자 하였다. 선분 분말의 열분석 결과 승온속도가 증가할 수록 발열개시온도가 저온부로 이동하고 있으며, 발열량도 크게 증가하였다. 또한, 자연발화 실험결과 전분의 양이 증가할수록 훈소 개시온도가 낮아지고, 연소형태는 모두 훈소였다. 자연발화 시험기 내부가 송풍상태일 때 보다 무풍상태로 실험하였을 경우 훈소 개시시간이 다소 빨라지고 있으며, 발열최고온도도 크게 나타났다.

• 한국자동차공학회논문집
• /
• 제10권3호
• /
• pp.61-69
• /
• 2002

To meet stringent LEV and ULEV emission standards, a considerable amount of development work was necessary to ensure suitable efficiency and durability of catalyst systems. The main challenge is to cut off the engine cold-start emissions. It is known that up to 80% of the total hydrocarbons(THC) are exhausted within the first five minutes in case of US FTP 75 cycle. Close-Coupled Catalyst(CCC) provides fast light-off temperature by utilizing the energy in the exhaust gas. However, if some malfunction occurred at engine operation and the catalyst temperature exceeds 1050$\^{C}$, the catalytic converter is deactivated and shows the poor conversion efficiency. This paper presents effEcts of engine operating conditions on catalytic converter temperature in a SI engine, which are the indications of catalytic deactivation. Exhaust gas temperature and catalyst temperature were measured as a function of air/fuel ratio, ignition timing and misfire rates. Additionally, light-off time was measured to investigate the effect of operating conditions. It was found that ignition retard and misfire can result in the deactivation of the catalytic converter, which eventually leads the drastic thermal aging of the converter. Significant reduction in light-off time can be achieved with proper control of ignition retard and misfire, which can reduce cold-start HC emissions as well.

• 한국안전학회지
• /
• 제30권5호
• /
• pp.1-7
• /
• 2015

This paper is aimed to analyze the electrical and thermal signal such as ignition possibility, ignition time, thermal characteristics and arc fault power that are associated with electrical fire in case of the occurrence of series arc at IV wiring used for interior wiring at commercial power source. In order to analyze the signal, series arc was induced by generating the constant vibration through vibrating device in the one phase (R phase) and ignition possibility was analyzed along the condition of current value by adding cotton material to the contact point of wiring. The ignition time is shortened as the electric current value increased, burning time is not associated with current value and the temperature rose up to $740^{\circ}C$ though it was not ignited. It was checked out that the temperature was the energy source enough that can generate the fire related with insulation aging of wiring and the inflammable. The possibility of electrical fire by series arc was shown as more than 12% at 5A, more than 42% at 20A and arc showed 27W at 5A, 180W at 20A. It was confirmed that the possibility of electrical fire exists at the condition as above and the circuit breaker did not operate. This data can be used as the reference value for the investigation of electrical fire or development of the circuit breaker.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
• /
• pp.545-550
• /
• 2012

고에너지 금속 분말은 높은 용융점을 가진 산화피막의 점화방해 효과로 인해 점화가 용이하지 않다. 따라서 점화를 위해서는 단시간에 높은 온도의 열적 공간을 형성할 수 있는 점화원이 필요하며 스팀 플라즈마 점화원은 탄화수소 계열의 점화원, 수소-산소 점화원, 레이져 점화원과 다르게 짧은 시간에 안정적으로 5,000 K 이상의 열적 공간을 형성할 수 있다. 또한 스팀을 작동가스로 사용하므로 친환경적이며 경제적이다. 따라서 본 연구는 스팀 플라즈마 점화기를 연소 시스템에 적용하기 위한 기초 연구로서 방출 분광법을 사용하여 플라즈마의 온도 분포 및 화학종을 분석하였으며, 연소시스템에 적용하여 금속 분말의 점화를 가시적으로 확인하였다.

• 한국자동차공학회논문집
• /
• 제7권9호
• /
• pp.10-19
• /
• 1999

In this study , a simple method has been developed to detect the required spark voltage by using the primary spark voltage instead of the secondary spark voltage. Through engine motoring experiments, this method testified to be quite satisfactory. Though the required spark voltage is affected by many in-cylinder conditions, temperature is one of the most important factors. The temperature increases significantly by combustion and the required spark voltage also changes by the temperature during the expansion stroke. On the basis of this fact, misfire can be monitored by comparing the required spark voltage between compression stroke and expansion stroke. So, in this study, two step ignition method is introduced to monitor combustion at expansion stroke. The test result shows that this method can be used to detect complex misfire pattern.