Energy considerations in spraying process of a spill-return pressure-swirl atomizer

Jedelský, Jan; Jícha, Miroslav

doi:10.1016/j.apenergy.2014.07.042

Cited by 46 publications

(22 citation statements)

References 47 publications

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“…shows the known dependency of the normalized SMD (Walzel ; Jedelsky and Jicha ): As the normalized SMD decreases the efficiency decreases as well. The reason for this is that a disproportionate amount of energy is needed to form very small spray drops as the energy losses due to friction, turbulence and acceleration increases (Lefebvre ; Jedelsky and Jicha ). For an increased viscosity the spray drop size increases as well.…”

Section: Resultsmentioning

confidence: 99%

“…However, when light heating oil with a viscosity of m 5 0.019 Pa s was used in the work of Jedelsky and Jicha (2013), the efficiency of the effervescent nozzle (2 3 10 24 < e < 2 3 10 23 ) was well below the efficiency of the investigated pressure swirl nozzle (2 3 10 23 < e < 2 3 10 22 ). Concerning the energy loss of the spraying nozzles, it has been shown that the main part of the energy supplied to pressure-swirl nozzles is lost within the swirl chamber due to viscous effects inside the liquid and due to friction on the inner walls (Jedelsky and Jicha 2014). In effervescent nozzles, the main part of the supplied energy is converted to turbulent internal/external flow and mixing of the two-phase fluid, to shear and frictional losses on passage walls and to momentum transferred to the surrounding atmosphere (Jedelsky and Jicha 2013).…”

Section: Introductionmentioning

confidence: 99%

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Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

Stähle

Schuchmann

Gaukel

2015

J Food Process Engineering

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We investigated two different sized pressure‐swirl nozzles and two twin‐fluid nozzles (external and internal mixing) spraying food liquids with different viscosities (0.001 Pa s ≤ µ ≤ 0.308 Pa s). Liquid pressures in the range of 0.2 MPa ≤ pL ≤ 30 MPa and gas‐to‐liquid ratios of 0.01 ≤ GLR ≤ 2.92 were applied. To compare the nozzles, we used two energy based approaches: The spraying efficiency e and the energy density EV. The spraying efficiency of all investigated nozzles was within reported ranges from literature. When described as a function of EV, the Sauter mean diameter (SMD) of the spray drops showed a power‐law dependency. Further, the SMD was independent of the size of the pressure‐swirl nozzles and the location (internal or external) of mixing in twin‐fluid nozzles. The pressure‐swirl nozzles were superior over the twin‐fluid nozzles when low viscous fluids were sprayed. However, only the twin‐fluid nozzles were able to spray viscosities of µ ≥ 0.143 Pa s satisfactorily. Overall, the EV concept showed to be an appropriate method for the prediction of SMD in dependency of energy relevant process parameters. Practical Application In spray‐drying of foodstuffs, the spray drop size is a crucial parameter. It depends on the physical properties of the liquid, on the type of nozzle and on the chosen process parameters. The nozzle comparison by means of the energy density EV enables the operator to quickly choose the needed energy, i.e. the process parameters, which has to be supplied to the nozzle at a specific viscosity and liquid volume flow rate to obtain the desired mean spray drop size. This facilitates the operation of spray dryers and the scale up of spraying nozzles.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance and Efficiency of Pressure‐Swirl and Twin‐Fluid Nozzles Spraying Food Liquids with Varying Viscosity

Stähle

Schuchmann

Gaukel

2015

J Food Process Engineering

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“…Another consideration here was the liquid film thickness when it first flowed from the orifice. The initial film thickness was in a reverse ratio to the nozzle exit diameter [75]. Hence, for the smaller nozzle diameters, the initial liquid film was thicker, and the sheet breakup took place in the longer lengths, as the other parameters of atomization and air flow were kept unchanged.…”

Section: Nozzle Outlet Diametermentioning

confidence: 99%

“…Finally, the nozzle diameter was varied between 0.1 and 0.3 mm, which is a typical range for diesel injection nozzles [73][74][75].…”

Section: Optimizationmentioning

confidence: 99%

Modelling and Optimization of a Small Diesel Burner for Mobile Applications

et al. 2018

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While extensive research has been done on improving diesel engines, much less has been done on auxiliary heaters, which have their own design challenges. The study analyzes how to optimize the combustion performance of an auxiliary heater, a 6 kW diesel burner, by investigating key parameters affecting diesel combustion and their properties. A model of a small diesel heater, including a simulation of fuel injection and combustion process, was developed step-wise and verified against experimental results that can be used for scaling up to 25 kW heaters. The model was successfully applied to the burner, predicting the burner performance in comparison with experimental results. Three main variables were identified as important for the design. First, it was concluded that the distance from the ring cone to the nozzle is essential for the fluid dynamics and flame location, and that the ring cone should be moved closer to the nozzle for optimal performance. Second, the design of the swirl co-flow is important, and the swirl number of the inlet air should be kept above 0.6 to stabilize the flame location for the present burner design. Finally, the importance of the nozzle diameter to avoid divergent particle vaporization was pointed out.

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“…In the present paper, an airblast atomizer was examined, since it has a simple geometry and used widely. Although other constructions have better efficiencies [19], however the process of atomization is well represented in this design. If the atomization velocity is low, the most unstable wave number can be calculated which allow an accurate estimate of the spray size distribution [20].…”

mentioning

confidence: 99%