Improved Atomization via a Mechanical Atomizer with Optimal Geometric Parameters and an Air-Assisted Component

Abstract

Atomization of liquid media is a key aim in various technological disciplines, and solutions that improve spray performance, while decreasing energy consumption, are in great demand. That concept is very important in the development of liquid fuel spray atomizers in high-efficiency microturbines and other generator systems with low inlet pressure and a wide range of power supply. Here we present a study of the liquid atomization characteristics for a new mechanical atomizer that has optimal geometric parameters and a preliminary swirl stage. In our air-assisted atomizer, air is introduced through a swirl chamber positioned at the exit of the mechanical atomizer. The optimized mechanical atomizer alone can achieve D32 drop diameters in the range of 80 to 40 µm at water supply pressures of 2 to 5 bar, respectively. The addition of an air swirl chamber substantially decreases drop sizes. At an air–liquid ratio (ALR) equal to 1, water pressures of 2.5 to 3 bar and air supply pressures 0.35 to 1 bar, D32 drops with diameters of 20–30 µm were obtained. In an air-assisted atomizer the parameters of the mechanical atomizer have a much stronger influence on drop diameters than do characteristics of the air-swirl chamber. Using a mechanical atomizer with optimal geometrical dimensions allows limiting the liquid supply pressure to 5 bar; but when an air-assisted component is introduced we can recommend an ALR ≈ 1 and an air supply pressure of up to 1 bar.

Microstructured Surfaces for Reducing Chances of Fomite Transmission via Virus-Containing Respiratory Droplets

“…The sprayed microdroplet size ranged from few tens of micrometers to hundreds of micrometers in diameter (Figures 2, S2, and S15), which was within the range of the dimension of respiratory microdroplets expelled during coughing, speaking, and breathing. 56−58 The velocity of the sprayed microdroplets at the nozzle was estimated to be approximately 3−5.5 mm/s (corresponding a Weber number of ≪1), 59 which was also within the range of the velocity of respiratory exhalation flow. 56,57 In this study, 0.25 or 0.5 mL of the nanoparticle solution was sprayed from the airbrush in 10 or 20 bursts at intervals of 1 s. To investigate the evaporation process and particle aggregation on the surfaces in Figures 2, 4, and 5, we sprayed the particle-laden solutions (0.25 mL) into the air per trial, and the mass deposited from the emitted solution onto each substrate of area ∼2 × 2 cm 2 was ∼9.5 mg (equivalent to ∼9−10 μL), as measured using a semimicrobalance (Figure S16).…”

An In Situ Study of Precursor Decomposition via Refractive Index Sensing in p-Type Transparent Copper Chromium Oxide

“…In a conventional spray pyrolysis system, MAD-0331-B1B Ultrasonic Atomisers were employed; they tend to produce a broad range of droplet sizes ranging from ≈10–30 μm. 18 The average droplet sizes produced by mist chemical vapour deposition (CVD) are found to be around 5.4 μm. 19 The main difference is a reduction in the active cooling from the nebulizing gas, as much lower gas flow rates are required.…”

“…In contrast to conventional spray pyrolysis, the different nebulization method of the solution allows the formation of high-quality, smooth films at lower substrate temperatures. In a conventional spray pyrolysis system, MAD-0331-B1B Ultrasonic Atomisers were employed; they tend to produce a broad range of droplet sizes ranging from ≈10–30 μm . The average droplet sizes produced by mist chemical vapour deposition (CVD) are found to be around 5.4 μm .…”

Measuring Liquid Droplet Size in Two-Phase Nozzle Flow Employing Numerical and Experimental Analyses

“…Many scholars have carried out in-depth research on the atomization characteristics of nozzles by analyzing the size and distribution of atomized particles from the viewpoints of both numerical and experimental evaluation. Factors affecting the atomization effect such as the gas, liquid flow, liquid temperature, and viscosity have been extensively experimentally evaluated in the literature [ 3 , 4 , 5 , 6 , 7 ]. For instance, Wang et al [ 6 ] studied the pressure swirl and air flow of an atomizer with experiments in which the droplet size and distribution under different fuel pressure were measured using a laser particle-size analyzer.…”

“…The results showed that the average particle diameter decreased as the pressure drop increased. Levitsky et al [ 7 ] improved atomization characteristics by reducing droplet size using an additional air vortex chamber. Furthermore, some scholars have found that structural and operating parameters, including liquid viscosity, surface tension, and the mass flow of air and fuel, may affect the atomization effect of pre-filming atomizers [ 8 , 9 , 10 ].…”