• 한국분무공학회지
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• 제19권4호
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• pp.155-166
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• 2014

This review will be concentrated on the spray characteristics of bioethanol and its derived fuels such as ethanol-diesel, ethanol-biodiesel in compression ignition (CI) engines. The difficulty in meeting the severe limitations on NOx and PM emissions in CI engines has brought about many methods for the application of ethanol because ethanol diffusion flames in engine produce virtually no soot. The most popular method for the application of ethanol as a fuel in CI engines is the blending of ethanol with diesel. The physical properties of ethanol and its derivatives related to spray characteristics such as viscosity, density and surface tension are discussed. Viscosity and density of e-diesel and e-biodiesel generally are decreased with increase in ethanol content and temperature. More than 22% and 30% of ethanol addition would not satisfied the requirement of viscosity and density in EN 590, respectively. Investigation of neat ethanol sprays in CI engines was conducted by very few researchers. The effect of ambient temperature on liquid phase penetration is a controversial topic due to the opposite result between two studies. More researches are required for the spray characteristics of neat ethanol in CI engines. The ethanol blended fuels in CI engines can be classified into ethanol-diesel blend (e-diesel) and ethanol-biodiesel (e-biodiesel) blend. Even though dodecanol and n-butanol are rarely used, the addition of biodiesel as blend stabilizer is the prevailing method because it has the advantage of increasing the biofuel concentration in diesel fuel. Spray penetration and SMD of e-diesel and e-biodiesel decrease with increase in ethanol concentration, and in ambient pressure. However, spray angle is increased with increase in the ethanol percentage in e-diesel. As the ambient pressure increases, liquid phase penetration was decreased, but spray angle was increased in e-diesel. The increase in ambient temperature showed the slight effect on liquid phase penetration, but spray angle was decreased. A numerical study of micro-explosion concluded that the optimum composition of e-diesel binary mixture for micro-explosion was approximately E50D50, while that of e-biodiesel binary mixture was E30B70 due to the lower volatility of biodiesel. Adding less volatile biodiesel into the ternary mixture of ethanol-biodiesel-diesel can remarkably enhance micro-explosion. Addition of ethanol up to 20% in e-biodiesel showed no effect on spray penetration. However, increase of nozzle orifice diameter results in increase of spray penetration. The more study on liquid phase penetration and SMD in e-diesel and e-biodiesel is required.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.1-9
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• 2014

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of petroleum fuels. Fast pyrolysis of biomass is one of several paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO) has been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of WPO in a diesel engine requires modifications due to low energy density, high water contents, high acidity, high viscosity, and low cetane number of the WPO. One possible method by which the shortcomings may be circumvented is to co-fire WPO with other petroleum fuels. WPO has poor miscibility with light petroleum fuel oils; the most suitable candidates fuels for direct fuel mixing are methanol or ethanol. Early mixing with methanol or ethanol has the added benefit of significantly improving the storage and handling properties of the WPO. For separate injection co-firing, a WPO-ethanol blended fuel can be fired through diesel pilot injection in a dual-injection dieel engine. In this study, the performance and emission characteristics of a dual-injection diesel engine fuelled with diesel (pilot injection) and WPO-ethanol blend (main injection) were experimentally investigated. Results showed that although stable engine operation was possible with separate injection co-firing, the fuel conversion efficiency was slightly decreased due to high water contents of WPO compare to diesel combustion.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.420-427
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• 2017

최근 화석연료의 고갈, 지구온난화 그리고 환경오염이 세계적인 공공의 문제로 대두됨으로써 신재생에너지에 관한 연구들이 많이 진행되고 있다. 이러한 신재생에너지들 중 바이오연료는 다루기 쉬울 뿐만 아니라, 낮은 가격과 풍부한 자원성이 미래에 화석연료를 대체할 수 있는 잠재성을 가지고 있다. 바이오연료 중 본 연구에서 사용한 급속 열분해유는 폐목재나 억새, 갈대와 같은 비식용작물에서부터 추출되었고, 이는 무한한 자원성 때문에 디젤엔진에서 디젤유를 대체할 신재생에너지로 주목받고 있다. 하지만 열분해유는 낮은 세탄가, 높은 점도, 높은 산도 그리고 낮은 발열량으로 인해 디젤엔진에 직접적으로 적용하기가 어렵다. 따라서 이러한 낮은 물질적 특성을 개선하기 위해서 본 연구에서는 에탄올과 같은 알코올계 연료와 혼합하여 투입하였다. 알코올계 연료인 에탄올이 열분해유의 저장 및 보관성에도 도움을 줄뿐 아니라 점도를 낮춰주어 엔진에 적용하기 수월하게 만들기 때문이다. 열분해유-에탄올 혼합연료를 파일럿 분사한 디젤유 이후 분사하여 연소시켜 이때의 연소 및 배기특성에 대해 고찰해 보았고, 그 결과로 미연탄화수소와 일산화탄소는 증가하는 경향을 띄지만 NOx와 PM이 현저히 줄어든 결과를 확인할 수 있었다.

• 한국자동차공학회논문집
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• 제17권2호
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• pp.82-89
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• 2009

In order to investigate the spray characteristics according to diesel and bioethanol blending with biodiesel fuel, macroscopic spray characteristics were analyzed from the comparison of the effect of the injection pressure, ambient pressure and density on the spray tip penetration and spray cone angle. In addition, spray atomization characteristics were studied with local and overall Sauter mean diameter (SMD) and the contour map of SMD distribution at various injection conditions. It was revealed that the spray tip penetration of biodiesel fuels blended with diesel and ethanol was shorter than that of an undiluted biodiesel fuel at low injection pressure. However, the difference of spray tip penetration among three test fuels reduces at a high injection pressure. Increase of the ambient gas density leads to the decrease of the spray tip penetration of three test fuels. When diesel and ethanol fuels add to an undiluted biodiesel fuel, spray cone angle increases due to the decrease of the fuel density at the same ambient pressure condition. On the other hand, the droplet mean diameter decreases due to the reduction of the kinematic viscosity and surface tension.

• 한국분무공학회지
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• 제21권3호
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• pp.144-154
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• 2016

This review will be concentrated on the spray characteristics of biobutanol and its blends fuels in internal combustion engines including compression ignition, spark ignition and gas turbine engines. Butanol can be produced by fermentation from sucrose-containing feedstocks, starchy materials and lignocellulosic biomass. Among four isomers of butanol, n-butanol and iso-butanol has been used in CI and SI engines. This is due to higher octane rating and lower water solubility of both butanol compared with other isomers. The researches on the spray characteristics of neat butanol can be classified into the application to CI and SI engines, particularly GDI engine. Two empirical correlations for the prediction of spray angle for butanol as a function of Reynolds number was newly suggested. However, the applicability for the suggested empirical correlation is not yet proved. The butanol blended fuels used for the investigation of spray characteristics includes butanol-biodiesel blend, butanol-gasoline blend, butano-jet A blend and butanol-other fuel blends. Three blends such as butanol/ethanol, butanol/heptane and butanol/heavy fuel oil blends are included in butanol-other fuel blends. Even though combustion and emission characteristics of butanol/diesel fuel blend in CI engines were broadly investigated, study on spray characteristics of butanol/diesel fuel blend could not be found in the literature. In addition, the more study on the spray characteristics of butanol /gasoline blend is required.

• 대한기계학회논문집B
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• 제38권6호
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• pp.501-511
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• 2014

바이오매스 원료로부터 급속열분해 반응을 통하여 생산되는 바이오 오일은 화석연료를 대체할 수 있는 잠재력을 가지고 있다. 하지만, 바이오 오일은 에너지 밀도와 세탄가가 낮고 점성도가 높은 연료의 한계성이 있으므로 디젤엔진에 적용하기에는 제한적이다. 따라서, 안정적인 연소를 얻기 위해서는 바이오 오일을 세탄가가 높은 연료와 유화하거나 혼합하여 사용하여야 한다. 하지만 바이오 오일과 화석연료는 극성이 달라서 서로 혼합되지 않으며 가장 손쉽게 혼합되는 연료는 알코올계 연료이다. 본 연구에서는 바이오 오일의 연료특성을 향상시키기 위하여 에탄올 연료와 혼합하였으며, 연료의 자발화 특성을 향상시키기 위하여 세탄가 향상제인 PEG 400, 2-EHN 도 첨가하였다. 또한 최대 15%의 바이오 오일이 혼합된 혼합연료를 디젤엔진에서 안정적으로 연소시키기 위하여 고압축비 피스톤도 적용하였다.

• 수산해양기술연구
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• 제53권1호
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• pp.89-97
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• 2017

Butanol has an ability to improve the ignition quality due to its lower latent heat of vaporization; it has an advantage to reduce a volume of a fuel tank because its energy density is higher than that of ethanol. Also, butanol-diesel oil blending quality is good because butanol has an effect to prevent the phase-separation between two fuels. Even if the blended oil contains water, it can reduce the corrosion of the fuel line. Thus, it is possible to use butanol-diesel oil blended fuel in diesel engine without modification, and it may reduce the environment pollution due to NOx and particulate and the consumption of diesel oil. Therefore, some studies are being advanced whether butanol is adequate as an alternative fuel for diesel engines, and the results of the combustion and exhaust gas emission characteristics are being presented. Though the injection and spray characteristics of butanol are more important in diesel combustion, the has not yet dealt with the matter. In this study, the influence in which differences of physical properties between butanol and diesel oil may affect the injection and spray characteristics such as injection rate, penetration, spray cone angle, spray velocity and process of spray development were examined by using CRDI system, injection rate measuring device and spray visualization system. The results exhibited that the injection and macroscopic spray characteristics of two fuels were nearly the same.

• 오토저널
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• 제11권1호
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• pp.31-43
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• 1989

제2보 (2)에서는 식물유를 연료로 사용할 경우 문제점인 시동성, 내구성 및 카본생성을 억제하기 위하여 물리적인 방법으로 해결책을 모색하였다. 그러나, 본 연구는 기관자체는 전혀 변형시키지 않고, 점도저감을 위하여 화학적인 방법 즉, 식물유를 알콜과 반응시켜 에스테르변 환을 하여 해결하려는 방법으로, 에스테르화한 연료를 사용하였을 때의 기관성능 및 카본 퇴적 문제를 비교, 시험한 것이다. 또, 기름이 식물유와 같이 지방산으로 이루어져 있다면, 어느 기름도 에스테르 변환이 가능하기 때문에, 생선기름인 정어리기름의 에스테르연료도 사용하여 그 이용 가능성을 확실히 하였다. 또한, 각종 연료의 연소성에 관하여 보다 상세한 검토를 하기 위하여, 이들의 연소율 파형을 2개의 Wiebe의 연소함수의 조합으로 표현함과 동시에 연소율 파형을 구성하는 각 변수를 해석함으로써, 기관성능치와 연소성과의 정량적인 관계에 대해서도 조사한 것이다.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.116-125
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• 2014

Pyrolysis oil (PO), derived from biomass through fast pyrolysis process have the potential to displace significant amounts of petroleum fuels. The PO derived from wood has been regarded as an alternative fuel to be used in diesel engines. However, the use of PO in a diesel engine is very limited due to its poor properties like low energy density, low cetane number, high acidity and high viscosity of PO. Therefore, one of the easiest way to adopt PO to diesel engine without modifications is blended with other fuels that have high centane number. However, PO that has high amount of polar chemicals is immiscible with non polar hydrocarbons of diesel or biodiesel. Thus, to stabilize a homogeneous phase of diesel/biodiesel-PO blends, a proper surfactant should be used. Nevertheless, PO which was produced from different biomass type have varied characteristics and this complicates the selection of a suitable additive for a specific PO-diesel emulsion. In this regard, a more simple approach such as the use of a co-solvent like ethanol or butanol to induce a more stable phase of the PO-diesel mixture could be a promising alternative. In this study, a diesel engine operated with diesel/biodiesel-PO-butanol blends was experimentally investigated. Performance and gaseous & particle emission characteristics of a diesel engine were examined under the engine loads of IMEP 0.2 ~ 0.8MPa.