The application of a multicomponent droplet vaporization model to gasoline direct injection engines

2003 ◽  
Vol 4 (3) ◽  
pp. 193-218 ◽  
Author(s):  
Y Ra ◽  
R. D. Reitz
Keyword(s):  
Heat Flux ◽  
Present Model ◽  
Direct Injection ◽  
Internal Heat ◽  
Droplet Surface ◽  
Gasoline Direct Injection ◽  
Gas Mixture ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Flash Boiling

A model for unsteady droplet vaporization is presented that considers the droplet temperature range from flash-boiling conditions to normal evaporation. The theory of continuous thermodynamics was used to model the properties and compositions of multicomponent fuels such as gasoline. In order to model the change of evaporation rate from normal to boiling conditions more realistically, an unsteady internal heat flux model and a new model for the determination of the droplet surface temperature are proposed. An explicit form of the equation to determine the heat flux from the surrounding gas mixture to the droplet/gas interface was obtained from an approximate solution of the quasi-steady energy equation for the surrounding gas mixture, with the interdiffusion of fuel vapour and the surrounding gas taken into account. The model was applied to calculate normal and boiling evaporation processes of droplets for various ambient temperatures and droplet temperatures. Single-droplet evaporation calculated using the present model was compared with the results calculated by using the standard evaporation routine of the KIVA-3V code. Also, simulations of the vaporization of a single-component fuel (iso-octane) were compared with multi-component fuel cases. The vaporization of a hollow cone spray of fuel injected into a cylindrical chamber was simulated for both normal and flash-boiling conditions using the KIVA-3V code implemented with the present model. In addition, the model was applied to a realistic gasoline direct injection engine.

A Model for Droplet Vaporization for Use in Gasoline and HCCI Engine Applications

2004 ◽  
Vol 126 (2) ◽  
pp. 422-428 ◽  
Author(s):  
Youngchul Ra ◽  
Rolf D. Feitz
Keyword(s):  
Heat Flux ◽  
Internal Heat ◽  
Droplet Surface ◽  
Fuel Vapor ◽  
Gas Mixture ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Flux Model ◽  
Heat Flux Model

A model for unsteady droplet vaporization is presented that considers the droplet temperature range from flash-boiling conditions to normal evaporation. The theory of continuous thermodynamics was used to model the properties and compositions of multicomponent fuels such as gasoline. In order to model the change of evaporation rate from normal to boiling conditions more realistically, an unsteady internal heat flux model and a new model for the determination of the droplet surface temperature is proposed. An explicit form of the equation to determine the heat flux from the surrounding gas mixture to the droplet-gas interface was obtained from an approximate solution of the quasi-steady energy equation for the surrounding gas mixture, with the inter-diffusion of fuel vapor and the surrounding gas taken into account. The model was applied to calculate evaporation processes of droplets for various ambient temperatures and droplet temperatures.

A Model for Droplet Vaporization for Use in Gasoline and HCCI Engine Applications

2002 ◽  
Author(s):  
Youngchul Ra ◽  
Rolf D. Reitz
Keyword(s):  
Heat Flux ◽  
Internal Heat ◽  
Droplet Surface ◽  
Fuel Vapor ◽  
Gas Mixture ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Flux Model ◽  
Heat Flux Model

A model for unsteady droplet vaporization is presented that considers the droplet temperature range from flash-boiling conditions to normal evaporation. The theory of continuous thermodynamics was used to model the properties and compositions of multi-component fuels such as gasoline. In order to model the change of evaporation rate from normal to boiling conditions more realistically, an unsteady internal heat flux model and a new model for the determination of the droplet surface temperature is proposed. An explicit form of the equation to determine the heat flux from the surrounding gas mixture to the droplet-gas interface was obtained from an approximate solution of the quasi-steady energy equation for the surrounding gas mixture, with the inter-diffusion of fuel vapor and the surrounding gas taken into account. The model was applied to calculate evaporation processes of droplets for various ambient temperatures and droplet temperatures.

Fuel Droplet Evaporation in a Supercritical Environment

2002 ◽  
Vol 124 (4) ◽  
pp. 762-770 ◽  
Author(s):  
G. S. Zhu ◽  
S. K. Aggarwal
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Ambient Pressure ◽  
Droplet Surface ◽  
Fuel Vapor ◽  
Phase Solubility ◽  
Liquid Density ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Wide Range

This paper reports a numerical investigation of the transcritical droplet vaporization phenomena. The simulation is based on the time-dependent conservation equations for liquid and gas phases, pressure-dependent variable thermophysical properties, and a detailed treatment of liquid-vapor phase equilibrium at the droplet surface. The numerical solution of the two-phase equations employs an arbitrary Eulerian-Lagrangian, explicit-implicit method with a dynamically adaptive mesh. Three different equations of state (EOS), namely the Redlich-Kwong (RK), the Peng-Robinson (PR), and Soave-Redlich-Kwong (SRK) EOS, are employed to represent phase equilibrium at the droplet surface. In addition, two different methods are used to determine the liquid density. Results indicate that the predictions of RK-EOS are significantly different from those obtained by using the RK-EOS and SRK-EOS. For the phase-equilibrium of n-heptane-nitrogen system, the RK-EOS predicts higher liquid-phase solubility of nitrogen, higher fuel vapor concentration, lower critical-mixing-state temperature, and lower enthalpy of vaporization. As a consequence, it significantly overpredicts droplet vaporization rates, and underpredicts droplet lifetimes compared to those predicted by PR and SRK-EOS. In contrast, predictions using the PR-EOS and SRK-EOS show excellent agreement with each other and with experimental data over a wide range of conditions. A detailed investigation of the transcritical droplet vaporization phenomena indicates that at low to moderate ambient temperatures, the droplet lifetime first increases and then decreases as the ambient pressure is increased. At high ambient temperatures, however, the droplet lifetime decreases monotonically with pressure. This behavior is in accord with the reported experimental data.

scholarly journals String flash-boiling in gasoline direct injection simulations with transient needle motion

2016 ◽  
Vol 87 ◽  
pp. 90-101 ◽  
Author(s):  
E.T. Baldwin ◽  
R.O. Grover ◽  
S.E. Parrish ◽  
D.J. Duke ◽  
K.E. Matusik ◽  
...  
Keyword(s):  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Flash Boiling

Fuel Droplet Evaporation in a Supercritical Environment

1999 ◽  
Author(s):  
G. S. Zhu ◽  
S. K. Aggarwal
Keyword(s):  
Experimental Data ◽  
Phase Equilibrium ◽  
Ambient Pressure ◽  
Droplet Surface ◽  
Fuel Vapor ◽  
Phase Solubility ◽  
Liquid Density ◽  
Ambient Temperatures ◽  
Droplet Vaporization ◽  
Wide Range

This paper reports a numerical investigation of the transcritical and supercritical droplet vaporization phenomena. The simulation is based on the time-dependent conservation equations for liquid and gas phases, pressure-dependent variable thermophysical properties, and a detailed treatment of liquid-vapor phase equilibrium at the droplet surface. The numerical solution of the two-phase equations employs an arbitrary Eulerian-Lagrangian, explicit-implicit method with a dynamically adaptive mesh. Three different equations of state (EOS), namely the Redlich-Kwong (RK), the Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) EOS, are employed to represent phase equilibrium at the droplet surface. In addition, two different methods are used to determine the liquid density. Results indicate that the predictions of RK-EOS are significantly different from those obtained by using the RK-EOS and SRK-EOS. For the phase-equilibrium of n-heptane-nitrogen system, the RK-EOS predicts higher liquid-phase solubility of nitrogen, higher fuel vapor concentration, lower critical-mixing-state temperature, and lower enthalpy of vaporization. As a consequence, it significantly overpredicts droplet vaporization rates, and underpredicts droplet lifetimes compared to those predicted by PR- and SRK-EOS. In contrast, predictions using the PR-EOS and SRK-EOS show excellent agreement with each other and with experimental data over a wide range of conditions. A detailed investigation of the transcritical droplet vaporization phenomena indicates that at low to moderate ambient temperatures, the droplet lifetime first increases and then decreases as the ambient pressure is increased. At high ambient temperatures, however, the droplet lifetime decreases monotonically with pressure. This behavior is in accord with the reported experimental data.

Modeling of Internal and Near-Nozzle Flow for a Gasoline Direct Injection Fuel Injector

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Kaushik Saha ◽  
Sibendu Som ◽  
Michele Battistoni ◽  
Yanheng Li ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Liquid Fuel ◽  
Numerical Study ◽  
Direct Injection ◽  
Computational Cost ◽  
Volume Averaging ◽  
Operating Conditions ◽  
Gasoline Direct Injection ◽  
Superheated Liquid ◽  
Fuel Injector ◽  
Flash Boiling

A numerical study of two-phase flow inside the nozzle holes and the issuing spray jets for a multihole direct injection gasoline injector has been presented in this work. The injector geometry is representative of the Spray G nozzle, an eight-hole counterbore injector, from the engine combustion network (ECN). Simulations have been carried out for a fixed needle lift. The effects of turbulence, compressibility, and noncondensable gases have been considered in this work. Standard k–ε turbulence model has been used to model the turbulence. Homogeneous relaxation model (HRM) coupled with volume of fluid (VOF) approach has been utilized to capture the phase-change phenomena inside and outside the injector nozzle. Three different boundary conditions for the outlet domain have been imposed to examine nonflashing and evaporative, nonflashing and nonevaporative, and flashing conditions. Noticeable hole-to-hole variations have been observed in terms of mass flow rates for all the holes under all the operating conditions considered in this study. Inside the nozzle holes mild cavitationlike and in the near-nozzle region flash-boiling phenomena have been predicted when liquid fuel is subjected to superheated ambiance. Under favorable conditions, considerable flashing has been observed in the near-nozzle regions. An enormous volume is occupied by the gasoline vapor, formed by the flash boiling of superheated liquid fuel. Large outlet domain connecting the exits of the holes and the pressure outlet boundary appeared to be necessary leading to substantial computational cost. Volume-averaging instead of mass-averaging is observed to be more effective, especially for finer mesh resolutions.

Prediction of spray collapse in multi-hole gasoline direct-injection fuel injectors

2018 ◽  
Vol 20 (1) ◽  
pp. 18-33 ◽  
Author(s):  
Sampath K Rachakonda ◽  
Arman Paydarfar ◽  
David P Schmidt
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ambient Pressure ◽  
Direct Injection ◽  
Gasoline Direct Injection ◽  
Nozzle Geometry ◽  
Fuel Injectors ◽  
Computational Fluid Dynamics Simulations ◽  
Flash Boiling ◽  
Dynamics Simulations

A parametric study was conducted to predict the conditions leading to spray collapse in multi-hole gasoline direct-injection fuel injectors using computational fluid dynamics simulations. The computational fluid dynamics simulations were performed using an in-house multi-dimensional code that accounts for thermal non-equilibrium and entrainment of the non-condensable gas and coupled with primary atomization. The simulations were performed for a fixed injection pressure and fuel temperature on nine different six-hole injectors. The parameters were varied to include the effects of the ratio of the ambient pressure to the saturation pressure (Pa/Ps), the drill angle, and the diameters of the nozzle and the counter bore, respectively, on the spray. The findings indicate that spray collapse results from a combination of the nozzle geometry, the thermodynamic conditions of the fuel, and the ambient pressure. Spray collapse was observed in injectors with a narrow arrangement of the nozzle holes under extreme flash-boiling conditions with very low ambient pressures and in the case of non-flash-boiling conditions with very high ambient pressures.

scholarly journals Effect of Extreme Temperatures and Driving Conditions on Gaseous Pollutants of a Euro 6d-Temp Gasoline Vehicle

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1011
Author(s):  
Barouch Giechaskiel ◽  
Victor Valverde ◽  
Anastasios Kontses ◽  
Ricardo Suarez-Bertoa ◽  
Tommaso Selleri ◽  
...  
Keyword(s):  
Heavy Traffic ◽  
Direct Injection ◽  
Urban Environments ◽  
Gasoline Direct Injection ◽  
Particulate Filter ◽  
Gaseous Emissions ◽  
Ambient Temperatures ◽  
Driving Conditions ◽  
On The Road ◽  
Cold Starts

Gaseous emissions of modern Euro 6d vehicles, when tested within real driving emissions (RDE) boundaries, are, in most cases, at low levels. There are concerns, though, about their emission performance when tested at or above the boundaries of ambient and driving conditions requirements of RDE regulations. In this study, a Euro 6d-Temp gasoline direct injection (GDI) vehicle with three-way catalyst and gasoline particulate filter was tested on the road and in a laboratory at temperatures ranging between −30 °C and 50 °C, with cycles simulating urban congested traffic, uphill driving while towing a trailer at 85% of the vehicle’s maximum payload, and dynamic driving. The vehicle respected the Euro 6 emission limits, even though they were not applicable to the specific cycles, which were outside of the RDE environmental and trip boundary conditions. Most of the emissions were produced during cold starts and at low ambient temperatures. Heavy traffic, dynamic driving, and high payload were found to increase emissions depending on the pollutant. Even though this car was one of the lowest emitting cars found in the literature, the proposed future Euro 7 limits will require a further decrease in cold start emissions in order to ensure low emission levels under most ambient and driving conditions, particularly in urban environments. Nevertheless, motorway emissions will also have to be controlled well.

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