Quantitative Measurements of Liquid and Vapor Distributions in Flash Boiling Fuel Sprays using Planar Laser Induced Exciplex Technique

Zhang, Gaoming; Xu, Min; Zhang, Yuyin; Zeng, Wei

doi:10.4271/2011-01-1879

Cited by 23 publications

(14 citation statements)

References 17 publications

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“…In the other hand, very high values of SMD were observed at 80°C and 100°C. At 80°C, the n-heptane already achieved the vapor pressure temperature, or, flash boiling point [1,2], meaning that instead of having liquid fuel droplets injection, a large amount of fuel vapor is injected by the fuel injector. Consequently, the laser cannot diffract accordingly in the vapor cloud, because its diffraction increases with vapor, thus masking the measurement of the droplet size.…”

Section: Resultsmentioning

confidence: 99%

“…The study presented here, investigates the influence of temperature on the injected spray when one of these heating devices heats fuel. Flash boiling point is also part of this study, when such heated fuel is then injected into a low pressure environment (for example, combustion chamber), the fuel temperature may exceed the boiling point that triggers the flash boiling [1,2]. The size of the injected droplet plays an important role to improve fuel combustion, especially at cold starts, and, consequently, reduce emission levels.…”

Section: Introductionmentioning

confidence: 99%

“…So, the most important methods to calculate the droplet size are: D(4,3) and D(3,2), which do not have dependency with particle numbers. D(4,3)is volume or mass moment mean and D[3,2] is surface area moment mean. In the automotive business the standard method for droplet size measurement is the D(3,2) SMD.…”

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confidence: 99%

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Temperature Influenceon the Fueldroplet Size

Neto¹,

Balbino²,

Lepsch³

et al. 2018

Blucher Engineering Proceedings

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The Bosch Flex Start System is a cold start concept aimed to ensure the start of internal combustion engines in the first attempt, mainly when they are filled with ethanol and face low temperature climates (below 15ºC). In that system, the fuel is preheated before being injected into the engine cylinders, through a fuel rail containing individual heaters. The heated fuel injection allows its entry into the engine combustion chambers in a more pulverized way, which, besides of ensuring the engine start in the first attempt, improves the ethanol burning, reduces the gases emission level and provides good steering conditions. It is known that, the smaller injected fuel droplet size (bigger pulverization) the better will be its combustion. Thus, this article will aim to present a study regarding the injected fuel temperature influence on the droplet size. According to data acquired from practical tests, it will be possible to evaluate the temperature vs droplet size curve and take decisions on how to optimize even more this system, mainly regarding energy efficiency of vehicle as a whole. Resumo O sistema Flex Start Bosch é um conceito de partida à frio que visa garantir a partida de motores de combustão interna na primeira tentativa, principalmente quando estes estão abastecidos com etanol e enfrentam climas de baixa temperatura (abaixo de 15ºC). Neste sistema, o combustível é pré-aquecido antes de ser injetado nos cilindros do motor, através de uma galeria equipada com aquecedores individualizados. A injeção do combustível aquecido permite que ele entre nas câmaras de combustão do motor de forma mais pulverizada, fato que, além de assegurar a partida na primeira tentativa, melhora a queima do etanol, reduz o nível de emissões e permite boas condições de dirigibilidade. É sabido que, quanto menor for o tamanho da gota do combustível injetado (maior pulverização), melhor será sua combustão. Assim, este artigo terá como objetivo apresentar um estudo sobre a influência da temperatura do combustível injetado sobre o tamanho da gota. Com base em dados obtidos através de provas práticas, será possível avaliar a curva de temperatura x tamanho de gota e tomar decisões para otimizar ainda mais este sistema, principalmente no que tange à eficiência energética do veículo como um todo.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temperature Influenceon the Fueldroplet Size

Neto¹,

Balbino²,

Lepsch³

et al. 2018

Blucher Engineering Proceedings

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“…n-Dodecane was chosen as the surrogate of diesel fuel. The mass ratio and properties of these two fuel-tracers were shown in Table 1 [32][33][34][35][36].…”

Section: Experimental Methodsmentioning

confidence: 99%

Study on Fuel Distribution of Wall-Impinging Diesel Spray under Different Wall Temperatures by Laser-Induced Exciplex Fluorescence (LIEF)

et al. 2018

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Spray wall-impingement has large effects on the pollutant emissions and thermal efficiency of engines. Different wall temperatures can affect the gas-liquid phase transition of the spray, and the temperature gradient from the ambient to the wall will cause a different mixture process in the region nearby the wall. However, there are few studies on spray wall-impingement with different wall temperatures, particularly on the liquid-gas phase transition of the spray. Therefore, in this paper, the effects of different wall temperatures on spray-impingement have been investigated in a high-temperature, high-pressure constant volume combustion vessel. Cooling equipment was used to adjust the temperature difference between the wall and the ambient gas. n-Dodecane was chosen as the diesel surrogate to study the spray process. The spray wall-impingement was tested by changing the injection pressures (P i ) and wall temperatures (T w ). The ambient temperature (T a ) and ambient pressure (P a ) were kept constant at 773 K and 4 MPa, and the distance (L) between wall and injector was set to 35 mm to mimic the radius of the combustion chamber in heavy-duty diesel engines. A laser-induced exciplex fluorescence (LIEF) technique was used to probe the vapor and liquid phases of the injected fuel. Results show that the liquid phases of the spray do not reach the wall except in the condition of low wall temperature and high injection pressure. The liquid penetration develops and then becomes constant after 1 ms from the start of injection. With the increase of injection pressures (600-1600 bar), the liquid concentration of the spray decreases; however the liquid penetration decreases insignificantly. The wall temperature and the injection pressure have little influence on the liquid interpenetration process. For the vapor phase of the spray, the high concentration regions (equivalence ratio (φ) > 1) mainly distribute in the area of 10 mm away from the impact point on the wall. With the decrease of wall temperatures, the high-concentration regions are enlarged at the near wall regions. However, at the injection pressure of 1600 bar, the influence of wall temperatures on the equivalence ratio is small. The decreasing wall temperature deteriorates the mixing process of the fuel and ambient gas, but the effect is weakened with the increase of injection pressure.

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“…In addition, Zhang et al [28] investigated flash boiling phenomenon which occur at some operating conditions when fuel is injected into the cylinder of a direct injection spark ignition engine. They applied the LIEF technique with two specially designed dopants, fluorobenzene (FB) and diethyl-methyl-amine (DEMA), in n-hexane to investigate the effects of such phenomenon on liquid and vapour phases of fuel sprays from a multihole injector in an optically accessible high pressure chamber.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous imaging of diesel spray atomisation and evaporation processes in a single-cylinder CR diesel engine

Herfatmanesh

Attar

Zhao

2013

Experimental Thermal and Fluid Science

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This document is the Accepted Manuscript version of the following article: Mohammad Reza Herfatmanesh, Mohammadreza Anbari Attar, and Hua Zhao, ???Simultaneous imaging of diesel spray atomisation and evaporation processes in a single-cylinder CR diesel engine???, Experimental Thermal and Fluid Science, Vol. 50, pp. 10-20, October 2013. ?? 2013 Elsevier Inc. This manuscript version is made available under the terms of the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/. The Version of Record is available online at DOI: https://doi.org/10.1016/j.expthermflusci.2013.04.019 :In direct injection diesel engines, combustion and formation of pollutants are directly influenced by the spatial and temporal distributions of the injected fuel. In this study mixture formation during the pre-combustion phase of a diesel engine was investigated using the laser-induced exciplex fluorescence (LIEF) technique. The main purpose of this investigation was to develop an experimental setup capable of providing the full-field view of both liquid and vapour phases of evaporating diesel sprays during the fuel injection process inside the combustion chamber of a diesel engine with optical access. An expanded laser beam was employed for full combustion chamber visualisation. In this study two model fuels were tested; one consisted of 89% decane, 10% ??-methyl-naphthalene and 1% TMPD and the other 88% decane, 10% ??-methyl-naphthalene and 2% TMPD. The spray atomisation and evaporation processes during the pre-combustion phase of a diesel engine were measured at an injection pressure of 1200 bar and the engine speed of 1500 rpm. The results demonstrated the capability of the full-field LIEF technique in simultaneous imaging of liquid fraction and fuel vapour distribution during high pressure fuel injection process. It also highlighted the effect of dopant concentration on the fluorescence intensity of liquid and vapour signals. The exciplex system containing 1% TMPD produced better visualisation of the liquid phase, though the crosstalk in the vapour phase precluded accurate detection of the vapour phase signal. In contrast, the exciplex system containing 2% TMPD resulted in satisfactory visualisation of the vapour phase; however the intensity of the liquid phase was compromised as a result. This was presumed to be mainly due to the spectral shift of the exciplex species and/or TMPD decomposition at elevated temperatures and pressures. ?? 2013 Elsevier Inc. All rights reserved

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Quantitative Measurements of Liquid and Vapor Distributions in Flash Boiling Fuel Sprays using Planar Laser Induced Exciplex Technique

Cited by 23 publications

References 17 publications

Temperature Influenceon the Fueldroplet Size

Temperature Influenceon the Fueldroplet Size

Study on Fuel Distribution of Wall-Impinging Diesel Spray under Different Wall Temperatures by Laser-Induced Exciplex Fluorescence (LIEF)

Simultaneous imaging of diesel spray atomisation and evaporation processes in a single-cylinder CR diesel engine

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