Marek Ochowiak

The effect of shear and extensional viscosity on atomization in medical inhaler.

The paper contains the results of experimental studies of water, aqueous solutions of glycerol and aqueous solutions of glycerol-polyethylene oxide (PEO) atomization process in a medical inhaler obtained by the use of the digital microphotography method. The effect of the shear and extensional viscosity on the drop size, drop size histogram and mean drop diameter has been analyzed. The obtained results have shown that the drop size increases with the increase in shear and extensional viscosity of liquid atomized. Extensional viscosity has a greater impact on the spraying process. It has been shown that the change in liquid viscosity leads to significant changes in drop size distribution. The correlation for Sauter mean diameter as function of the shear and extensional viscosity was proposed.

The effect of shear and extensional viscosities on atomization of Newtonian and non-Newtonian fluids in ultrasonic inhaler.

The paper contains results of the experimental study on atomization process of aqueous solutions of glycerol and aqueous solutions of glycerol-polyacrylamide (Rokrysol WF1) in an ultrasonic inhaler. In experiments the different concentration aqueous solutions of glycerol and glycerol-polyacrylamide have been tested. The results have been obtained by the use of laser diffraction technique. The differences between characteristics of ultrasonic atomization for test liquids have been observed. The analysis of drop size histograms shows that the different sizes of drops have been formed during atomization process. The present study confirmed the previous reports which suggested that the drops size changes with the increase in viscosity of solution changes in spray characteristics were also observed. It has been shown that the shear and extensional viscosities affect the process of atomization.

Rheology and Structure of Emulsions and Suspensions

This article contains the results of experimental investigation of the rheological characteristics and structures of emulsions and suspensions. The emulsions had the oil volume fraction in the range from 0.1 to 0.4. The suspensions with nanoparticles are represented by suspensions of silica with concentrations from 1 to 4%. Paprika and coffee suspensions with concentrations of 5, 10, and 20% were studied. The material was subjected to rheological measurements using a concentric cylinder viscometer in the shear rate range of 16.2 to 1326s−1. A lot of food products are either in the form of emulsions or suspensions whose rheological and interfacial properties are important to achieve stability of the products. The rheology and structure analysis is very important from the point of view of flow, friction factors and Reynolds number for non-Newtonian fluids and food production processes. To characterize emulsions and suspensions, first the particle size distributions were made. The experiments presented have shown that the rheological characteristics of composite systems (emulsions and suspensions) depend on concentration and properties of dispersed phase. Concentration of dispersed phase has an effect on the character of the fluid. The fluid can have Newtonian character at low concentrations of dispersed phase. Above certain concentrations the nature of non-Newtonian fluid will appear. Emulsions have a polydisperse character. Emulsions with ϕ up to 0.4 show approximately linear increase of emulsion viscosity on the oil concentration. Silica represents suspension with aggregates, agglomerates or network formed. The increase in shear rate causes gradual destruction of the structure. The rheological behaviors confirm these processes. The paprika and coffee suspensions have non-Newtonian rheological properties. The suspensions have more and more non-Newtonian characteristics increasing particles concentration. The solid particles do not form structures. The correlation equation for rheological properties of systems studied has been shown. The results may be used for example to verify numerical models or comparisons with respect to similar fluids.

Extensional viscosity measurements of concentrated emulsions with the use of the opposed nozzles device

This paper presents results of experimental studies on the apparent extensional viscosity of emulsions. The apparent extensional viscosity measurements were carried out with the use of a customized rheometer which utilizes stagnation flow between two opposing nozzles. Apparent extensional viscosity was determined for emulsions containing 60, 70 and 74 vol.% of dispersed phase. The emulsions were produced using a homogenizer equipped with different dispersing endings that resulted in emulsions characterized by different droplet sizes. The experimental results show that the value of apparent extensional viscosity of the emulsion is significantly influenced by the droplet size and by the concentration of dispersed phase. Apparent extensional viscosity as well as shear viscosity of the emulsions increases with the increase of the dispersed phase concentration and with the decrease of the droplet diameter. It has also been observed that the decrease in the diameter of droplets increases the ratio of the apparent extensional viscosity to the shear viscosity, known as the Trouton ratio.

Characterization of sprays for thermo-stabilized pneumatic nebulizer

The research presents the nebulizer spray chamber temperature controller responsible for controlling temperature of aerosol produced as a result of nebulizing process. The motivation to make an attempt to improve modern pneumatic devices was the shortage of this kind of apparatuses on the market allowing the production of thermos aerosol. A designed temperature controlling system for pneumatic nebulizers aims at increasing and stabilizing temperature of produced aerosols and increasing aerosol therapy safety. The system is intended for producing aerosol in the process of pneumatic nebulization with the temperature similar to that of the human body. Experiments that were carried out confirmed good performance of the device. It was proved that with the increase of temperature the amount of big droplets fall and the entire spectrum of the droplet diameter moves towards smaller droplet diameter values. Reduction of liquid viscosity related to the increase of temperature leads to the reduction of droplet diameter and, as a result, the reduction of the Sauter mean diameter value.

The modified swirl sedimentation tanks for water purification.

This paper discusses design, evaluation, and application for the use of swirl/vortex technologies as liquid purification system. A study was performed using modified swirl sedimentation tanks. The vortex separators (OW, OWK, OWR and OWKR) have been studied under laboratory conditions at liquid flow rate from 2.8⋅10-5 to 5.1⋅10-4 [m3/s]. The pressure drop and the efficiency of purification of liquid stream were analyzed. The suspended particles of different diameters were successfully removed from liquid with the application of swirl chambers of proposed constructions. It was found that damming of liquid in the tank increases alongside liquid stream at the inlet and depends on the tank construction. The efficiency of the sedimentation tanks increases alongside the diameters of solid particles and decrease in the liquid flow rate. The best construction proved to be the OWR sedimentation tank due to smallest liquid damming, even at high flow rates, and the highest efficiency of the purification liquid stream for solid particles of the smallest diameter. The proposed solution is an alternative to the classical constructions of sedimentation tanks.

Atomization performance of effervescent atomizers with gas-liquid internal mixing

Atomization performance of effervescent atomizers with gas-liquid internal mixing The paper contains the results of experimental studies on water atomization process in effervescent nozzle in one-phase and two-phase systems. The gas phase flow rate causes the changes in characteristic parameters of atomization. The gas flow rate has certain effect on the Sauter Mean Diameter SMD values. SMD for airliquid systems investigated is decreasing with increase of gas volume rate. It is observed that SMD values are increasing with increase of liquid volume rate. The larger SMD values for one-phase flow in comparison with two-phase flow have also been observed. The increase of SMD value has been observed with a decrease of an outlet diameter of an effervescent nozzle.

The effect of additional aeration of liquid on the atomization process for a pneumatic nebulizer

&NA; At this paper the effect of aeration on the droplet size distribution of the aerosol have been analyzed. The atomization process was carried out using a pneumatic nebulizer which was equipped with a modified nebulizer cup. This modified nebulizer cup was combined with an additional source of gas bubbles. The measurements of the droplet sizes obtained by the use of the digital microphotography method and analyzed by Image‐Pro Plus software. The analysis of the experimental studies proved that an increase in the flow rates of additional gas leads to the increase in the number of small droplets and the decrease of the number of drops of large diameter. Additionally, the mean droplet diameter decreases with the increase of the flow rate of aeration gas. A correlation equation was proposed, which describes the relationship between the mean diameter of droplet and the volumetric flow rate of additional gas. The increase in the bubble volume discharging through a single orifice causes the increase of the flow rate of aeration gas. The modifications of construction of atomizer lead to the better effectiveness of nebulization. Graphical Abstract Figure. No caption available.

Atomizers with the Swirl Motion Phenomenon

The liquid atomization is very important and widespread process in many branches of industry and in agriculture. The technology development, better construction solutions to improve atomization process for the specific application are searched for. Depending on the assignment on which the atomizer is to be used, there are different requirements. Atomization itself doesn’t mean that the process proceeds in a correct and that performance of the spray system is optimum. The application of the effervescent atomizer witch swirl motion phenomenon improves of atomization process compared to pressure-swirl or effervescent atomizers, affects aerosol quality, improves atomization process and ensures its optimization. The spray parameters are influence by many factors: geometric dimensions, liquid properties and operational conditions. The dimensions of atomizer outlet, mixing chamber, aerator have the most important impact on the atomization process. Viscosity and surface tension affect Sauter mean diameter. Viscosity also affects spray angle, while the significant influence of the surface tension on the spray angle has not been shown.

Practical Aspects of Settling Tanks Design

The following work discusses the phenomenon of solid particle settling, presents the characteristics of suspensions and the fundamentals of sedimentation. The velocity of a solid particle free settling has been characterized as well as the sedimentation velocity. Additionally, the paper tackles upon the issue of a liquid stream purification and wastewater purification, where various devices used for the purpose have been characterized, such as horizontal settling tanks, swirl settling tanks and Dorr settling tanks. A special attention was paid to the characteristics of swirl settling tanks, their advantages and potential applications. Also, the outcomes of the research performed to develop the said devices have been described. The aforementioned research considered the influence from the advanced settling tank design components introduced over the purification efficiency of liquid streams from heavy and light fractions, such as inlet or outlet connectors or a partition inside the device. The damming of liquid and the values of local resistance factors have been evaluated as they differ in various technical solutions for settling tanks. The research allowed to determine the construction marked with the highest efficiency in purification of liquid stream, which gives us a possibility to develop the option for analyses with regards to the devices of this type.