**6. References**

0.5

750 950 1150 1350 1550

**Diesel Biodiesel**

**Pressure Drop Across Orifice (bar)**

0.6

0.7

0.8

**Normalized Turbulent Kinetic Energy**

0.9

1

100 Fuel Injection in Automotive Engineering

300

0.0

(a) (b) Fig. 10. Computed flow properties at the nozzle exit versus pressure drop in the injector for diesel and biodiesel fuels: (a) mass flow rate and injection velocity; (b) discharge coefficient

The flow inside the nozzle is critical in spray, combustion, and emission processes for an internal combustion engine. Inner nozzle flows are multi-scale and multi-phase in nature, hence, challenging to capture both in experiments and simulations. Cavitation and turbulence generated inside the nozzle is known to influence the primary breakup of the fuel, especially in the near nozzle region. The authors capture the in-nozzle flow development using the two-phase flow model in FLUENT software. The influence of definition of cavitation inception is first analyzed by implementing an improved criterion for cavitation inception under turbulent conditions. While noticeable differences between the standard and advanced criteria for cavitation inception are observed under twodimensional flow conditions, thorough development and validation is necessary before

Since the injector nozzle is a critical component of modern internal combustion engines, the influence of orifice geometry and fuel properties on in-nozzle flow development were also characterized. Both cavitation and turbulence was reduced using a hydroground nozzle compared to a base production nozzle. This will result in significant differences in spray, combustion, and emission behaviour also for these nozzles. Biodiesel being a lucrative blending agent for compression ignition engine applications was then compared to diesel fuel for inner nozzle flow development. Cavitation and turbulence generated inside the nozzle was observed to be lower for biodiesel compared to diesel fuel. Additionally, boundary conditions in terms of cavitation, turbulence, and flow variables were obtained for spray combustion simulations as a function of time for the detailed nozzle flow simulations.

The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S. Department of Energy Office of Science

0.2

0.4

0.6

**Discharge Coefficient**

0.8

1.0

350

400

**Injection Velocity (m/s)**

450

500

0

and normalized TKE.

**5. Acknowledgment** 

**4. Conclusion** 

750 950 1150 1350 1550 **Pressure drop across orifice (bar)**

implementing in real injection flow simulations.

**8-10%**

**4-5%**

**Pb=30bar**

0.0025

0.005

**Mass flow rate (kg/s)**

0.0075

0.01

**Diesel # 2 Biodiesel**


**6** 

*Covilhã, Portugal* 

Jorge Barata and André Silva

**Numerical Simulation of Biofuels Injection** 

The use of alternative biofuels in the co-generation of electricity and heat, as well as in the transportation sector, presents major benefits, such as the conservation of the environment due to their renewable origin, the reduction of fossil fuels use or the conservation of

The more important biofuels currently under investigation are the bio-alchohols and their derived ethers, and the vegetable oils and their derived esters. Methyl esters of rapeseed oils or soybean oils have been tested in Diesel engines, and in spite of the strong dispersion of the published results, there are indications that their use is a promising solution to the problems originated with the raw vegetable oil due to their higher viscosity, boiling temperature, final

The present work presents a numerical study on evaporating biofuel droplets injected through a turbulent cross-stream. This study uses an Eulerian/Lagragian approach to account for turbulent transport, dispersion, evaporation and coupling between both processes in practical spray injection systems, which usually include air flows in the combustion chamber like swirl, tumble and squish in I.C. engines or crossflow in boilers and gas turbines. An array of evaporating biofuel droplets through a crossflow is studied, and a comparison of the droplet fuel dispersion and evaporation with conventional fuels is performed. A summary of the main general characteristics properties of the conventional

The evaporation of droplets in a spray involves simultaneous heat and mass transfer processes in which the heat for evaporation is transferred to the drop surface by conduction and convection from the surrounding hot gas, and vapour is transferred by convection and diffusion back into the gas stream. The overall rate of evaporation depends on the pressure, temperature, and transport properties of the gas; the temperature, volatility and diameter of the drops in the spray; and the velocity of the drops relative to that of the surrounding gas (Faeth, 1983, 1989, 1986).

Godsave (1953) and Spalding (1953) gave the basic droplet vaporization/combustion model for an isolated single-component droplet in a stagnant environment. Since then this model has been studied extensively both experimentally and theoretically. These studies have been reviewed extensively by several authors during the past decades (e.g. Williams, 1973; Faeth, 1977; Lefebvre 1989; Law, 1982; and Sirignano, 1978), and are mostly dedicated to study the

agricultural activity in regions where the food production is being reduced.

temperature of distillation and point of obstruction of cold filter (Tinaut, 2005).

fuels and biofuels tested in the present investigation is presented in Table 1.

**1. Introduction** 

*Aerospace Sciences Department, University Beira Interior,* 

