• 한국자동차공학회논문집
• /
• 제5권1호
• /
• pp.87-100
• /
• 1997

The ability of turbulence model to accurately describe the complex characteristics of the flow field and the fuel spray is of great importance in the optimum design of diesel engine. The numerical simulations of the flow field and the spray characteristics within the combustion chamber of direct injection model entgine are performed to examine the applicability of turbulence model. The turbulence models used are the RNG $\varepsilon$ model and the modified $\varepsilon$ model which included the compressibility effect due to the compression/expansion of the charges. In this study, the predicted results in the quiescent condition of direct injection model engine show reasonable trends comparing with the experimental data of spray characteristics, i. e., spray tip penetration, spray tip velocity. The results of eddy viscosity obtained using the $\varepsilon$ model in the spray region is significantly larger than that obtained using the RNG $\varepsilon$ model. The application of the RNG model seems to have some potential for the simulations of the spray characteristics, e. g., spray tip penetration, spray tip velocity, droplets distribution over the $\varepsilon$ model.

• 한국안전학회지
• /
• 제25권6호
• /
• pp.103-108
• /
• 2010

In this study, tank truck incidents of road transport of hazardous materials to experimental investigated the potential fire hazard. Real scale fire was to perform experiments for on this qualitative and quantitative data collection and analysis. Particularly affected by radiant heat from the flames caused and damage estimates range investigated accordingly. Flame temperature, internal temperature of tank and emitted radiation from the flames was investigated. The flame of light oil spill caused a fire at a temperature of about $300^{\circ}C$ high in comparison with the methanol by combustion of diesel and methanol, according to the difference, the flame duration changes varies depending on the Burning rate, amount of radiant heat flux from light oil fire was 4 times increases compared with fire of methanol. Depending on spill locations(kinds of road surfaces, absorbing rate) and the longer the duration of the flame important factors for the internal temperature of tank truck rise was found. Dirt roads than paved road accident in a fire caused by leakage of hazardous was could the higher the damaged. Therefor, Fire suppression activities should be required in particular to be around.

• 한국분무공학회지
• /
• 제16권3호
• /
• pp.146-151
• /
• 2011

LPG(Liquified Petroleum Gas) fuel for vehicles has lots of advantages such as low emission level, cheaper fuel cost and enough infrastructure. Therefore it arouses interest as an alternative engine to reduce emission of diesel engines. Especially MPI(Multi Point Injection) type LPLi(Liquid Phase LPG injection) system could have overcome the disadvantages of mixer types such as low engine performance, decreased charging efficiency and cold starting difficulty. However ice formation on the nozzle tip and intake port due to the freezing of moisture around the components is often observed in LPLi systems. This icing phenomenon is the direct cause of unstable engine combustion, resulting in engine emissions. Therefore in this research, a spray visualization test for LPG injection was carried out to obtain the basic information of an LPLi injector, then the effects of butane and propane mixing rates on ice formation at the intake port and nozzle tip was investigated. As a result, the icing characteristics of them showed contrary results according to the mixing rates.

• 한국기계가공학회지
• /
• 제18권1호
• /
• pp.94-100
• /
• 2019

This study was conducted on a high-temperature/high-pressure washer in which low-pressure cold water in a boiler is heated to a temperature range of $70{\sim}80^{\circ}C$ by supplying diesel combustion heat. The high-temperature water is sent to a compressor to increase its pressure to 200 bar, thereby making high-temperature/high-pressure water, which is sprayed through a spray nozzle. In the results of this study, the spray temperature of the high-pressure washing was shown to be the highest when the ratio between the actual amount of combustible air and the theoretical amount of air was 1:1 and the energy consumption rate of the low-pressure boiler type high-pressure washer was shown to be much lower than that of the high-pressure boiler type high-pressure washer.

• 한국분무공학회지
• /
• 제27권4호
• /
• pp.195-202
• /
• 2022

Recently, the global automobile market is rapidly changing from internal combustion engine vehicles to eco-friendly vehicles including electric vehicles. Among eco-friendly vehicles, LPG vehicles are low in fine dust and are suggested as a realistic way to replace diesel vehicles. In addition, it is more economical than gasoline in its class, showing a cost-saving effect. In Korea, the business of converting gasoline into LPG is active. Research is being conducted to apply this to hybrid vehicles. In this study, the difference in energy consumption efficiency was analyzed when LPG fuel was applied by selecting a 2-liter GDI hybrid electric vehicle. The operation of the hybrid system according to various driving characteristics was confirmed by selecting the WLTC mode. As a result, it was confirmed that the BSFC was about 5% lower than that of gasoline fuel when using LPG fuel. This is due to the active operation of the motor while driving. Optimization is required as battery consumption increases from an energy perspective.

• Journal of Advanced Marine Engineering and Technology
• /
• 제39권5호
• /
• pp.542-547
• /
• 2015

Since the oil price has been significantly jumped for several years, a heavy oil of low quality has been mainly used in the diesel engine of the merchant ship. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, Inconel 625 filler metal were welded with GTAW method in the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. Furthermore, the corrosion current density of the weld metal zone revealed the lowest value, having the highest value of hardness. The corrosive products with red color and local corrosion like as a pitting corrosion were considerably observed at the base metal zone, while these morphologies were not wholly observed in the weld metal zone. In particular, the polarization characteristics such as impedance, polarization curve and cyclic voltammogran associated with corrosion resistance property were well in good agreement with each other. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the Inconel 625 electrode.

• 생물환경조절학회지
• /
• 제28권4호
• /
• pp.293-301
• /
• 2019

본 연구는 온실의 온도와 $CO_2$농도를 높이기 위해 DME버너용 연료로 DME가스를 사용했을 때 DME 연소가스의 성능을 결정하고 겨울에 상추와 양배추의 엽록소 함량 그리고 무게와 건조무게에 대한 영향정도를 조사하기 위해 수행되었다. 각각 온실1과 온실2에 처방 된 DME-1과 DME-2 처방은 덕트의 평균 DME 유량 $17.4m^3min^{-1}$과 $10.2m^3min^{-1}$으로 구성됐으며, 대조군(DME-3)으로 남겨진 온실3에는 DME 가스가 공급되지 않았다. DME 공급 시간은 각각 주차 별로 1주차는 하루당 0.5시간, 2주차는 1시간, 3주차는 1.5시간, 4주차는 2시간으로 설정하였다. 각각 처방마다 엽록소 함량과 상추와 배추의 건조 전, 후 중량을 측정했으며, 연구결과 무처리구인 온실3과 비교하여 온실1과 온실2의 $CO_2$ 농도는 각각 265%, 174% 증가하였고, 온도의 경우 $4.8^{\circ}C$, $3.10^{\circ}C$ 상승하였다. DME 가스를 제외한 다른 조건이 같은 온실에서 재배된 상추와 양배추의 엽록소 함량과 생체중, 건물중은 온실1에서 (유의적으로) 가장 높았으며, 온실2는 대조구 온실보다 높았다. 이러한 결과는 DME가스 연소에 의한 $CO_2$ 농도 차이에 기인된 것으로 판단된다. 일반적으로 가스연소에 의해 발생되는 유해가스 증상은 나타나지 않았으며 동절기 난방과 $CO_2$ 공급이 동시에 필요할 경우 DME가스가 기존의 경유 또는 LPG 등을 대체할 수 있는 가능성을 확인하였다. 향후 정밀한 연구를 통하여 효율적인 난방방식으로의 검토가 적극 필요하다고 판단된다.

• 한국가스학회지
• /
• 제14권3호
• /
• pp.41-45
• /
• 2010

DME(Dimethyl Ether)는 물리적 성질이 LPG와 유사하여 청정하면서 LPG와 잘 섞이고, 세탄가가 디젤연료와 유사하여 디젤을 대체할 수 있는 환경 친화적인 차세대 대체에너지이다. DME는 천연가스, CBM, biomass 등 다양한 원료로부터 제조할 수 있으며 탄소-탄소 직접결합이 없어 연소시 배기가스중에 검댕이나 황산화물이 없다. 한국가스공사에서 개발한 DME 공정은 크게 4개의 section으로 구분할 수 있다. 먼저 합성가스를 제조하는 syngas section 에서는 다양한 합성가스 비율을 제조할 수 있다. 이것은 tri-reforming을 완성하는 과정에서 합성가스 비율을 약 4.0~1.0의 범위로 조절할 수 있다. 두 번째로 $CO_2$ removal section에서 제거되는 $CO_2$는 약 92~99%로서 DME 합성반응기로 유입되는 $CO_2$의 최대 농도는 8%를 넘지 않아야 한다. 세 번째로 DME synthesis section에서 DME 합성 반응기의 반응온도는 높을수록 활성이 좋지만 촉매의 장기 활성을 위해서는 적정한 온도를 유지하는 것이 바람직하다. 마지막으로 DME purification section에서는 99.5%이상의 고순도의 DME를 정제할 수 있다.

• 대한기계학회논문집B
• /
• 제36권2호
• /
• pp.217-224
• /
• 2012

비도로용 차량의 경우 대부분 디젤엔진을 사용하여 엔진의 특성상 PM과 NOx의 배출이 많은 단점이 있다. 승용 및 상용 디젤 차량의 경우 CRDI 및 후처리 장치를 적용하였고 후처리 장치로 DOC/DPF를 장착함으로써 PM은 약 90% 이상 저감 가능하다. 상반관계인 NOx는 EGR 사용을 통해 1차적으로 NOx 배출량을 감소시키고 LNT, LNC, Urea-SCR 등의 DeNOx 시스템으로 NOx의 배출량을 보다 현저히 저감시켜 배기규제를 만족시키고 있다. 본 연구에서는 tier 4 interim 배기규제를 만족하기 위해 56kW급 오프로드 차량으로 연구를 진행하였다. NOx의 감소를 위해 WGT와 전자 제어방식의 HPL EGR 시스템을 적용하였고 CO와 THC, PM 배출가스를 줄이기 위해 DOC와 DPF를 사용하였다. EGR 시스템을 적용하기 위해 각 조건에 대한 기본 실험을 실시하여 EGR map을 작성하였다. 작성된 map을 NRTC 모드에서 시험하여 map의 적용성을 검증하고 tier 4 interim 배기규제 만족여부를 파악하였다.

• 수산해양기술연구
• /
• 제26권1호
• /
• pp.65-75
• /
• 1990

Bosch법과 Zeuch법의 분사율 측정기를 직접설계, 제작하여 분사율 측정실험을 행한 결과 다음과 같은 결론을 얻었다. 1. Bosch법 분사율 측정기는 분사량의 참 값에 대한 측정오차가 약 $\pm$1%로 정밀도와 신뢰성이 높았다. 2. Bosch법 분사율 측정기에서, 분사율은 연료펌프의 회전수와 부하가 증가할수록 높아지는 반면, 분사기간(ms)은 회전수가 증가할수록 짧아짐을 알 수 있었다. 3. 본 실험에서는, 동일조건하의 단발분사가 연발분사에 비해 전체적으로 분사율이 낮고 기관의 1 cycle당 분사량도 약 30% 정도 적었다. 4. Zeuch법 분사율 측정기로 구한 체적강성계수의 값은 배압이 증가할수록 증가함을 알 수 있었다. 5. Zeuch법 분사율 측정기는 Bosch법 분사율 측정기에 비해 정밀도가 낮았다.