Ultrasonic Atomization System Research Articles

Prevention of Dry Cracking of Excavated Earthen Sites at Han Yangling Museum Using Ultrasonic Wetting

ABSTRACT Dry cracking is the most perilous weathering process threatening the structural stability of earthen sites. Even in a high-humidity environment, dry cracking resulting from soil water evaporation cannot be entirely prevented. This study examined use of an ultrasonic atomization system to create an atmosphere of water-mist above excavated earthen sites. This system was selected to facilitate liquid water transport from air to the soil, to prevent dry cracking of earthen sites. A validation experiment was conducted to assess the effectiveness of the system for wetting earthen sites. The experimental results revealed that the system could maintain a high water content at an excavated earthen sites with a minimal gradient in soil water content and significantly reduced salt concentrations in the soil surface layer. The HYDRUS-2D model was calibrated using 15 d of experimental data, enabling numerical simulation of water and salt transport at an excavated earthen site under various wetting scenarios for a one-year period. The simulations demonstrated a steady increase in water content and a gradual decrease in the water content gradient at the excavated earthen site when short wetting intervals were used, thereby enhancing the structural stability of the site. These findings offer a vital reference for the application of ultrasonic atomization in the wetting of excavated earthen sites to prevent dry cracking.

Establishment of the optimal predictive model of die steel SKD 11 micromilling via nanofluid (graphene)/ultrasonic atomizing minimum quantity lubrication

This study is mainly utilized nanofluid (graphene) and ultrasonic atomization system to process SKD11 mold steel in micromilling to improve the quality of processed products, find the optimal quality characteristics, and construct an accurate prediction model. In this study, Taguchi’s robust design is adopted. The L18(21×37) orthogonal table is used to find the optimal parameter combinations for each quality characteristic, and the micromilling force and micromilling temperature are used as characteristic indicators. The control variables are the average thickness of nanographene, weight percent concentration, ultrasonic atomization amount, spindle speed, feed rate, air pressure, nozzle angle, nozzle distance. Also, a back propagation neural network (BPNN) is used to predict the micromilling processing mode. Taguchi method is used to optimize the hyper parameters in the neural network to improve the accuracy of the prediction model, reduce the input of the number of training samples, and then build a neural network prediction model that can accurately predict the quality characteristics of micromilling force and micromilling temperature. The prediction results show that the milling force parameter value error between the micromilling force model prediction and the single target optimization is 0.55%. The error between the micromilling temperature model prediction and the single-target optimization of the micromilling temperature value is 5.90%.

Application of Graphene Nanofluid/Ultrasonic Atomization MQL System in Micromilling and Development of Optimal Predictive Model for SKH-9 High-Speed Steel Using Fuzzy-Logic-Based Multi-objective Design

This paper focuses on using nanofluid (graphene)/ultrasonic atomization minimum quantity lubrication (MQL) in micromilling for SKH-9 high-speed steel. Utilizing the special properties of graphene, which has excellent thermal conductivity, it is found that it successfully lowers the cutting temperature generated during processing, reduces tool wear, and improves the quality of micromilling products. Using a self-developed ultrasonic atomization system effectively improves the agglomeration of nanoparticles in nanofluids and increases the lubrication efficiency of nanoparticles. The experimental plot is robustly designed, and the L18(21 × 37) orthogonal table is used to find the optimal combination of parameters. The control factors are the average thickness of the nanographene, density of nanofluid, spindle speed, distance of nozzle, feed rate, amount ultrasonic atomization, air pressure, nozzle angle, and using gray correlation analysis with fuzzy inference to find more heavy quality characteristics. Finally, the optimal parameter combination of multi-quality characteristics enhanced by nanofluid (graphene)/ultrasonic atomization MQL is compared with the base fluid/ultrasonic atomization MQL, nanofluid (MWCNTs)/ultrasonic atomization MQL, whereas the differences in micromilling force, temperature, tool wear, and workpiece burr are discussed. The results indicate that the use of nanofluid (graphene)/ultrasonic atomization MQL has better results than other lubrication methods.

Rapid Reduction of Graphene Oxide Thin Films on Large-Area Silicon Substrate

Graphene oxide thin films were fabricated on 8-inch silicon/silicon dioxide (Si/SiO2) wafers for nanoelectronic applications. The fabrication was performed using an ultrasonic spray coating method and reduced by rapid thermal processing (RTP). The micrometer-sized droplets from an ultrasonic spray of stable dispersion Graphene Oxide (GO) in ethanol form uniforms films on large-area silicon substrates. Optical microscope images clearly showed uniform thin films resulting from the overlapped of GO dispersion droplets. The chemical and structural parameter characterization were performed by field emission scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). The spray coating process using an ultrasonic atomizer system with optimum parameters and the thermal reduction process using RTP at 1100 °C produces low sheet resistance values ranging from 1 to 4 kOhms/sq with non-uniformity less than 20%.

Real-time monitoring system for polystyrene coating material deposition onto QCM sensor using ultrasonic atomizer spray

The polymer coating on a Quartz Crystal Microbalance can be done using spin coating, dipping, spray coating (airbrush) and ultrasonic spray coating. Film thickness and surface morphology of the coating depend on the coating method. Using spray coating, one can control the film thickness and also the morphology by controlling the speed, polymer-solvent particle size, concentration and duration of the deposition process. This paper presents a method for monitoring the deposition of polystyrene onto the QCM sensor by using an ultrasonic atomizer system. The atomizer was working using an ultrasonic generator at 55 kHz. Theoretically, the atomizer was able to produce a mist of solvent and polymer with a diameter of around 28 microns. The system was equipped with a frequency counter which able to monitor the resonance frequency of the sensor being coated in every second with a resolution of 1 Hz. The frequency change was related to the amount of the deposited polymer and solvent on the sensor surface; it means that the deposited polymer can be measured and monitored during the coating process. The deposited polystyrene and its solvent were monitored directly by observing the frequency change of the sensor is coated. For 10 MHz sensor, the resolution was equaled to a deposited mass of 4.2ng. It means that the amount of the coating material to be deposited on the sensor surface can be controlled with high resolution. The evaporation of the solvent after coating process was also able to be monitored directly. The benefit offered by this system besides controlled mass deposited is also the simplicity of the system.

Ultrasonic atomization of graphene derivatives for heat spreader thin film deposition on silicon substrate

We report the development of graphene derivative deposition on silicon wafers through ultrasonic atomization process. The study includes the ultrasonic atomizer system design, process development, characterization of the nanomaterial, and its heat transfer analysis. In this study, ultrasonic atomizer system was developed to deposit graphene oxides on 8”silicon wafer for seamless integration with semiconductor processes. The atomization process was performed in a chamber under control environment to ensure high quality of deposition process.

Performance investigation on the ultrasonic atomization liquid desiccant regeneration system

Liquid desiccant dehumidification systems have accumulated considerable research interest in recent years for their great energy saving potential in buildings. Within the system, the regenerator recovering liquid desiccant plays a major role in its performance. When the ultrasonic atomization technology is applied to atomize the desiccant solution into numerous tiny droplets with diameters around 50μm, the regeneration process could be greatly enhanced. To validate this approach, a novel ultrasonic atomization liquid desiccant regeneration system (UARS) was studied in this work. An Ideal Regeneration Model (IRM) was developed to predict the regeneration performance of the UARS. Additionally, thorough experiments were carried out to validate the model under different operating conditions of the desiccant solution and air stream. The model predicted values and the experimental results coincided, with the average deviation less than 7.9%. The performance of UARS was compared with other regeneration systems from the open literature, while a case study was conducted for the power consumption and energy saving potential of UARS. It was found that the ultrasonic atomization technology enabled utilization of lower-grade energy for desiccant regeneration with the regeneration temperature lowered as much as 4.4°C. In addition, a considerable energy saving potential of up to 23.4% could be achieved by the UARS for regenerating per unit mass flow of desiccant solution, while the power consumption of the ultrasonic atomization system was less than 7.0% of total energy cost. Moreover, when the UARS is integrated with the ultrasonic atomization assisted dehumidifier, energy savings can reach up to 60.4% as compared with the packed-bed system. This study validated the feasibility and energy saving potential of applying ultrasonic atomization technology to liquid desiccant regeneration systems.

The effect of steam sterilization on recombinant spider silk particles

In this work, the recombinant spider silk protein eADF4(C16) was used to fabricate particles in the submicron range using a micromixing method. Furthermore, particles in the micrometer range were produced using an ultrasonic atomizer system. Both particle species were manufactured by an all-aqueous process. The submicroparticles were 332nm in average diameter, whereas 6.70μm was the median size of the microparticles. Both particle groups showed a spherical shape and exhibited high β-sheet content in secondary structure. Submicro- and microparticles were subsequently steam sterilized and investigated with respect to particle size, secondary structure and thermal stability. Sterilization temperature and time were increased to assess the thermal stability of eADF4(C16) particles. Actually, particles remained stable and their properties did not change even after autoclaving at 134°C. Both, the untreated and the autoclaved submicroparticles showed no overt cytotoxicity on human dermal fibroblasts after incubation for 72h. The eADF4(C16) particles were already loaded with proteins and small molecules in previous studies. With that, we can provide a highly promising parenteral drug delivery system based on a defined polypeptide carrier, manufactured with an all-aqueous process and being fully sterilizable.

Controllable fuel cell humidification by ultrasonic atomization

Compared with the conventional bubble-type humidifier used for PEMFC (proton exchange membrane fuel cell) humidification, ultrasonic atomization has the advantages of a small size, ease in refilling and changing temperature, and more importantly, controllable humidity. This study develops a unique ultrasonic atomization system that includes a gas heating pipe, an ultrasonic driving circuit, an ultrasonic atomizer, and humidity sensors. The reactive gases used are hydrogen and air. The gas humidity increases due to the ultrasonic micro water droplets that blend with the gases. The humidity is controlled by adjusting either the heating temperature or the driving voltage. In addition, the size of the micro water droplets can be manipulated by adjusting the driving frequency. An increased driving frequency leads to a smaller mean droplet diameter, which increases the humidification efficiency. A relative humidity of at least 90% can be maintained for gas flow rates between 1 and 25 LPM. The conventional bubble-type humidification can achieve only ∼80% relative humidity under the same conditions. The I–V curve also indicates that an optimal humidity is required for improved performance. Thus, a dynamic controllability of the humidification is important, especially for high-capacity FC (fuel cell) performance.

Controllable fuel cell humidification by ultrasonic atomization

Compared to the conventional bubble type used for PEMFC (proton exchange membrane fuel cell) humidification, ultrasonic atomization has the advantages of smaller size, it is easy to refill and change temperature, and, more importantly, humidity controllability. To improve the performance of the FC, this study developed a unique ultrasonic atomization system, including a gas heating pipe, ultrasonic driving circuit, ultrasonic atomizer, and humidity sensors. The reactant gases used are hydrogen and air. When the reactant gas obtains sufficient heat from the heating pipe and enters the ultrasonic atomizer, gas humidification is increased due to the ultrasonic micro water droplets blending into the gases. The humidity is controllable by adjusting either the heating temperature or driving voltage. The size of the micro water droplets can also be manipulated by adjusting the driving frequency. A higher driving frequency leads to smaller droplet mean diameter, which in turn increases the humidification efficiency. At least 90% relative humidity can be maintained under the condition that the flow rate of anode and cathode's reactant gas is restricted to between 1LPM and 25LPM. Under the same condition, the conventional bubble type can only achieve around 80%.

Process considerations related to the microencapsulation of plasmid DNA via ultrasonic atomization

An effective means of facilitating DNA vaccine delivery to antigen presenting cells is through biodegradable microspheres. Microspheres offer distinct advantages over other delivery technologies by providing release of DNA vaccine in its bioactive form in a controlled fashion. In this study, biodegradable poly(D,L-lactide-co-glycolide) (PLGA) microspheres containing polyethylenimine (PEI) condensed plasmid DNA (pDNA) were prepared using a 40 kHz ultrasonic atomization system. Process synthesis parameters, which are important to the scale-up of microspheres that are suitable for nasal delivery (i.e., less than 20 microm), were studied. These parameters include polymer concentration; feed flowrate; volumetric ratio of polymer and pDNA-PEI (plasmid DNA-polyethylenimine) complexes; and nitrogen to phosphorous (N/P) ratio. PDNA encapsulation efficiencies were predominantly in the range 82-96%, and the mean sizes of the particle were between 6 and 15 microm. The ultrasonic synthesis method was shown to have excellent reproducibility. PEI affected morphology of the microspheres, as it induced the formation of porous particles that accelerate the release rate of pDNA. The PLGA microspheres displayed an in vitro release of pDNA of 95-99% within 30 days and demonstrated zero order release kinetics without an initial spike of pDNA. Agarose electrophoresis confirmed conservation of the supercoiled form of pDNA throughout the synthesis and in vitro release stages. It was concluded that ultrasonic atomization is an efficient technique to overcome the key obstacles in scaling-up the manufacture of encapsulated vaccine for clinical trials and ultimately, commercial applications.

Reservoir-Type Microcapsules Prepared by the Solvent Exchange Method: Effect of Formulation Parameters on Microencapsulation of Lysozyme

A new microencapsulation technique based on the solvent exchange method was implemented using an ultrasonic atomizer system to encapsulate a protein drug in mild conditions. The reservoir-type microcapsules encapsulating lysozyme as a model protein were prepared by inducing collisions between the aqueous droplets containing lysozyme and the droplets of organic solvent with dissolved poly(lactic acid-co-glycolic acid) (PLGA). The main focus of the study was to examine formulation variables on the size and the encapsulation efficiency of the formed microcapsules. The formulation variables examined were concentrations of mannose in the aqueous cores, NaCl in the aqueous collection medium, and PLGA in organic solvent. The mean diameter of the microcapsules ranged from 40 microm to 100 microm. Smaller microcapsules showed lower encapsulation efficiencies. The resulting microcapsules released native lysozyme in a sustained manner, and the release rate was dependent on the formulation conditions, such as the concentration and molecular weight of the polymer used. The solvent exchange method does not induce lysozyme aggregation and loss of its biological activity. The solvent exchange method, implemented by the ultrasonic atomizer system, provides an effective tool to prepare reservoir-type microcapsules for delivering proteins.

On the physical properties of indium oxide thin films deposited by pyrosol in comparison with films deposited by pneumatic spray pyrolysis

This paper presents the structural, electrical and optical properties of indium oxide thin films deposited by (1) pyrosol technique in comparison with the results that were obtained by spraying the same solution using (2) a pneumatic spray system. Films were deposited at temperatures ranged between 623 and 863 K onto glass substrates and investigated by scanning electron microscopy and X-ray diffraction. The transmission and reflectance spectra were determined in the 260–2600 nm spectral range. Resistivity as low as 6×10 −3 Ω cm with high optical transmission (>90%) have been obtained in In 2O 3 thin films deposited, when the ultrasonic atomizer system was used. The figures of merit Φ TC= T 10/ R sh of films deposited using the two methods were calculated at different wavelengths. The advantages of the pyrosol method were obvious. The atomization of solution using the ultrasonic system leads to an improvement of the structural and electrical properties of films and allows the deposition of films with high transparency and electrical conductivity at lower substrate temperatures (∼673 K) compared to that needed in the case of pneumatic spray method (⩾773 K).

Design and Performance of an Ultrasonic Atomization System for experimental combustion applications

AbstractAlthough common atomizing systems efficiently produce sprays, a range of droplet sizes is generally obtained and the distribution is often difficult to control in terms of liquid or gaseous flow rates. It is shown that an alternative system, based on ultrasonic surface instabilities, is well suited for experimental applications where all parameters have to be controlled. Technological aspects of ultrasonic atomization are described and the droplet spray produced by an ultrasonic atomizer is characterized experimentally.

A small ultrasonic atomizer for liquid fuels

This paper describes a small ultrasonic atomizer system that has been developed for the combustion of liquid fuels in a burner with a thermal output of 20,000Btu/h. The technique of ultrasonic atomization offers significant advantages over conventional methods since it requires no high-pressure pump and it operates well with a variety of fuels. The system can be throttled or modulated and operates well at any fuel flow rate up to the design maximum.