Secondary Atomization of Fuel Oil and Fuel Oil/Water Emulsion through Droplet-Droplet Collisions and Impingement on a Solid Wall

Abstract

This paper presents findings from an experimental study investigating the secondary atomization of liquid fuel droplets widely used in the heat and power industry exemplified by fuel oil and environmentally promising fuel oil/water emulsion. The scientific novelty comes from the comparative analysis of the critical conditions and integral characteristics of the secondary atomization of the liquid and composite fuels with the greatest potential for power plants. Here, we used two fuel atomization schemes: droplet–droplet collisions in a gas and droplets impinging on a heated solid wall. The temperature of the liquids under study was 80 °C. The velocities before collision ranged from 0.1 m/s to 7 m/s, while the initial droplet sizes varied from 0.3 mm to 2.7 mm. A copper substrate served as a solid wall; its temperature was varied from 20 °C to 300 °C. The main characteristics of droplet interaction were recorded by a high-speed camera. Regime maps were constructed using the experimental findings. It was established that the critical Weber number was several times lower when water and fuel oil droplets collided than during the collision of fuel oil droplets with 10 vol% of water. The secondary atomization of fuel oil/water emulsion droplets by their impingement on a heated solid wall was found to reduce the typical sizes of liquid fragments by a factor of 40–50. As shown in the paper, even highly viscous fuels can be effectively sprayed using primary and secondary droplet atomization schemes. It was established that the optimal temperature of the fuel oil to be supplied to the droplet collision zone is 80 °C, while the optimal substrate temperature for the atomization of fuel oil/water emulsion droplets approximates 300 °C.

Experimental and numerical analysis of the emulsification of oil droplets in water with high frequency focused ultrasound

“…At Oh near and above 1, the critical We elevates for the different breakup modes with viscosity increment. There are reports that the critical We can increase to ∼ 25 and ∼ 50 at Oh of 1 and 3, respectively [41] , [42] , [43] , [44] , [45] , [46] . One of such estimations of the viscosity influenced We can be described by Brodkey correlation [41] : where is the critical Weber number with strong viscous effect, is the critical Weber number with negligible viscosity influence and is the Ohnesorge number.…”

An Experimental Study on the Performance and Emissions of an 8% Water-in-Diesel Emulsion Stabilized by a Hydrophilic Surfactant Blend

“…Due to differences in the volatility of the continuous and dispersed phases (diesel and water), a swift disintegration of the parent droplets occurs [14,20]. The vapor expansions of the more volatile water droplets break and split the fuel droplets apart, inducing a secondary atomization, in the aftermath of the primary process at the injector, finely fragmenting the fuel droplets into smaller particles [21]. During this phase, the previously mentioned dual events of puffing and micro-explosion come to the forefront.…”

“…nergies 2024, 17, x FOR PEER REVIEW 3 of 17 atomization, in the aftermath of the primary process at the injector, finely fragmenting the fuel droplets into smaller particles [21]. During this phase, the previously mentioned dua events of puffing and micro-explosion come to the forefront.…”