Spray and evaporation characteristics of ethanol and gasoline direct injection in non-evaporating, transition and flash-boiling conditions

Energy Conversion and Management

Hong

2016

Self Cite

a b s t r a c tEthanol direct injection plus gasoline port injection (EDI + GPI) is a new technology to utilise ethanol fuel more efficiently and flexibly in spark ignition engines. One issue needs to be addressed in the development of EDI + GPI is the ethanol fuel's low vapour pressure and large latent heat which slow down the ethanol's evaporation and result in the mixture unready for combustion by the time of spark ignition and the consequent increase of CO and HC emissions. Heating the ethanol fuel to be directly injected (EDI heating) has been proposed to address this issue. This paper reports the investigation of the effect of EDI heating on the combustion and emissions of a research engine equipped with EDI + GPI. The results showed that EDI heating effectively reduced the CO and HC emissions of the engine due to the increase of evaporation rate and reduced fuel impingement and local over-cooling. The reduction of CO and HC became more significant with the increase of ethanol ratio. When the temperature of the ethanol fuel was increased by 40°C, the CO and HC were reduced by as much as 43% and 51% respectively in EDI only condition at the original spark timing of 15 CAD BTDC, and 15% and 47% respectively at the minimum spark advance for best torque (MBT) timing of 19 CAD BTDC. On the other hand, the NO emission was slightly increased, but still much smaller than that in GPI only condition due to the strong cooling effect and low combustion temperature of EDI. The IMEP and combustion speed were slightly reduced by EDI heating due to the decrease of injector fuel flow rate and spray collapse of flash-boiling. The largest decrease of IMEP was 5% at the original spark timing and 3% at the MBT timing. Moreover, at the MBT timing, the IMEP increased continuously with the increase of ethanol ratio in the entire range from 0% to 100%. This indicated that the decrease of IMEP in high ethanol ratio conditions at the original spark timing could be avoided by adjusting the spark timing. Therefore EDI heating is effective to address the issues of ethanol's low evaporation rate in low temperature engine environment and over-cooling effect at high ethanol ratio condition in the development of EDI + GPI engine.

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 98%

Investigation of the effect of heated ethanol fuel on combustion and emissions of an ethanol direct injection plus gasoline port injection (EDI + GPI) engine

Energy Conversion and Management

Hong

2016

Self Cite

“…The results showed the advantages of using pure ethanol fuel in the tested conditions. However, as neat fuel, ethanol may be not suitable to power SI engines in some conditions because of its low volatility, low heating value and high enthalpy of vaporization, especially under cold conditions [5][6][7]. At present, therefore, As reviewed above, following the demonstration of advantages of EDI+GPI, it is needed to investigate the in-cylinder flow details of EDI+GPI dual-injection by CFD simulation.…”

Section: Introductionmentioning

confidence: 99%

Effect of injection timing on mixture formation and combustion in an ethanol direct injection plus gasoline port injection (EDI+GPI) engine

Hong

2016

Energy

Self Cite

Ethanol direct injection plus gasoline port injection (EDI+GPI) is a new technology to utilise ethanol fuel more effectively and efficiently in spark-ignition engines by taking the advantages of ethanol fuel and direct injection, such as the cooling effect and anti-knock ability. A full cycle numerical modelling including both port and direct injection sprays was performed to understand the mechanisms behind the experimental results of the EDI+GPI engine. The turbulence-chemistry interaction of the two-fraction-mixture partially premixed combustion was solved by a five-dimensional presumed Probability Density Function table.Effects of direct injection timing on fuel evaporation, mixing, wall-wetting, combustion and emission processes were investigated. The results showed that when the direct injection timing was retarded, the mixture around the spark plug became leaner and the distribution of equivalence ratio became more uneven.Moreover, late direct injection resulted in severe fuel impingement and caused local over-cooling effect and over-rich mixture. Consequently, the combustion speed and temperature were decreased by retarded direct injection timing, leading to reduced NO emission and increased HC and CO emissions. Finally, numerical modelling was performed to investigate the strategy of injecting small amount of ethanol fuel on reducing the fuel impingement and incomplete combustion caused by late direct injection.

Anais Do XXIV Simpósio Internacional De Engenharia Automotiva

“…Este vapor formado pode prejudicar a penetração da injeção de combustível, pois ocorre um "estouro" que descaracteriza o jato. Um trabalho interessante sobre o assunto foi feito por Huang et al [7] sobre influência da temperatura do combustível (etanol e gasolina) antes da injeção na existência do flash boiling. Eles observaram que a injeção com temperatura levemente superior (4 K) à saturação não causa flash boiling.…”

Section: Partida Do Motor (De P1 a P2)unclassified

Fenômenos de termodinâmica e transferência de calor em sistemas de aquecimento de combustível para partida a frio de motores de combustão interna

Oliveira¹,

Alegre²,

Santos³

et al. 2016

RESUMONo Brasil, o etanol é um popular combustível alternativo à gasolina, especialmente após 2003, quando veículos Flexfuel foram introduzidos no mercado. No entanto, há complicações durante a partida a frio do motor com etanol, devido à sua baixa pressão de vapor e alto ponto de fulgor. A primeira solução para superar o problema foi injeção de gasolina para partida do motor em baixas temperaturas, utilizando uma linha de combustível própria para este fim. Recentemente, a solução de injeção de combustível aquecido foi adotada no mercado pelas montadoras. Seu projeto envolve conceitos de transferência de calor e termodinâmica que devem ser considerados para projetar os componentes e prever seu desempenho, de forma a aquecer o combustível o mais rápido possível de forma segura. O presente trabalho é uma breve discussão sobre a termodinâmica do aquecimento de combustível e fenômenos de transferência de calor que ocorrem neste processo. Maior atenção é dada à transferência de calor por ebulição, com os resultados experimentais deste fenômeno com etanol e gasolina. No entanto, como já bastante conhecido pelo setor automotivo, motores movidos a etanol tem bastante dificuldade de partir em baixas temperaturas. Isto ocorre devido à baixa pressão de vapor e ao alto ponto de fulgor do etanol (vide Tabela 1 com algumas propriedades do etanol e da gasolina). Apesar de o Brasil ser um país tropical com temperaturas médias relativamente