Droplet Separator Research Articles

Optimization mathematical model of a contact air cooler for a mine turbocompressor

Purpose. Establishing the dependencies of rational parameters of turbocompressor contact air coolers on the operating mode and initial conditions. Methodology. The methods of analytical research, mathematical modeling, physical modeling, and mathematical statistics were used in the study. Findings. As a result of the research, an optimization mathematical model of the mine turbocompressor air cooler was developed, which allows establishing its rational parameters depending on the initial conditions and operating modes of the turbocompressor. The adequacy of the theoretical studies was proved on a specially designed experimental setup. The obtained dependences make it possible to minimize the theoretical flow rate at the inlet to the uncooled section of the turbocompressor, which reduces the specific energy consumption for the compressed air production. Originality. For the the first time, a method has been developed for determining the rational parameters of contact air coolers when the initial temperature of water, air, and air pressure changes, which allows developing a methodology for the constructive calculation of the contact cooling system of mine turbocompressors. Practical value. Compressed air is widely used in all industries. It is one of the most common energy carriers in industrial enterprises, and the devices associated with its distribution and processing are an energy-intensive complex industrial energy system; the level of its perfection depends on the performance of technological processes that use compressed air. Compressed air is widely used in the mining industry (ore mining and fuel production). Compressed air is produced by turbocompressors. To increase the efficiency of the compressor, compressed air coolers are used. A significant weakness of the standard compressor cooling system is the rapid contamination of the heat exchange surfaces of air coolers with scale layers, which leads to a decrease in their efficiency and an increase in the specific energy consumption for compressed air production. This disadvantage is not found in the Venturi tube – centered droplet separator contact air coolers. As a result of the study, the dependencies were obtained and used to develop a methodology for the constructive calculation of contact air coolers for a mine turbocompressor.

Experimental study on the influence of electrical conductivity of hygroscopic compounds on the performance of a hygroscopic cycle

Dry climate conditions and the risk of desertification have increased significantly due to the effects of climate change. This fact, combined with the growing energy demand, leads to the need of research focused on improving the performance and efficiency of power plants. In the Hygroscopic Cycle Technology, recently implemented at industrial scale, steam condensation is performed in an absorber using solutions of hygroscopic compounds in water. Hygroscopic effects increase the condensing temperature for a given pressure, allowing the implementation of dry coolers at high ambient temperatures and eliminating cooling water consumption. In this work, due to their relevance in the cycle performance and control, the influence of the concentration of hygroscopic salts in the cycle has been studied, providing insight into proper operational ranges and key parameters. An experimental study of the influence of make-up water quality, with the concentration of impurities measured by water electrical conductivity and cycle mass flow ratio values has been performed in a pilot plant. The results, used to validate a mass and species conservation model, have allowed to obtain operational charts of the cycle and may help to reduce the amount of instrumentation required for cycle control. It was found that the decrease in electrical conductivities with boiler blowdowns in the cycle stabilized at a boiler blowdown ratio of 5%. Blowdown ratios above 10% did not result in substantially lower boiler Cycles Of Concentration in comparison with the increase of thermal energy losses and pumping power (0.42 kJ/kg for each additional 1% of blowdown). It was also found that the ratio between the cooling reflux and turbine steam conductivity had to be higher than 1.1 for condensation by absorption to occur, and that a minimum blowdown ratio of 0.04% was required to avoid using a droplet separator to control live steam quality. Hence, a compromise in the boiler blowdown ratio must be found for each particular application. Finally, hygroscopic effects in condensing pressure and temperature have been experimentally verified at pilot plant scale, leading to potentially higher cycle power output values and higher temperatures in the cooling stream of industrial power cycles, which may make it easier to reject heat from the cycle.

Experimental Study of a Compact Microwave Applicator for Evaporation of Airflow-Entrained Droplets.

In many energy and process engineering systems where fluids are processed, droplet-laden gas flows may occur. As droplets are often detrimental to the system’s operation, they need to be removed. Compact engineering solutions for the removal of entrained droplets are difficult to achieve with conventional flow control and heat transfer approaches and thus droplet removal devices are hence often costly and bulky. In this study, we analyzed the potential of a compact technology based on droplet capture and in situ evaporation by microwave heating. For that, we designed a microwave applicator containing a porous droplet separator for capturing and evaporating droplets. The application of open-cell ceramic foams as filter medium reduced 99.9% of the volumetric flow of droplets, while additional microwave exposure increases reduction to 99.99%. In addition, microwave-heated foams prevent droplet re-entrainment and structure-borne liquid accumulation within foams, thus avoiding water clogging and flooding.

Experimentally Validated Design of an Anode Recirculation Blower for Pem Fuel Cells Under Variable Fluid Composition

Abstract This paper focuses on the design, construction and the experimental testing of an anode recirculation blower (ARB) based on a turbo-compressor for PEM-FCs. The blower presented consists of a high-speed centrifugal compressor, driven by a so-called media-gap motor. Additionally it includes a droplet separator to eliminate liquid water from the anode loop. The aerodynamic design is based on 1D-correlations and 3D-numerical CFD simulations. Different gas compositions of hydrogen, nitrogen and water vapor are considered in the design, depending on the operating points of a PEM-FC. The gas composition has a significant influence on the achievable pressure ratio at constant compressor speeds, depending mainly on the specific heat capacity of the gas. Performance maps for different gas compositions are calculated using CFD for the designed ARB. A prototype is built and tested. The results validate the CFD predictions and show that the operating range of a PEM fuel cell can be covered with the present blower. In addition, it could be shown that an enthalpy-based approach using common characteristic numbers of turbomachines, allows converting performance maps - acquired with different gas compositions - into one another. This allows the performance map prediction for different gas compositions based on existing performance maps. This approach is illustrated by numerical and experimental results.

Covariation of droplet size distribution and air humidity in fog: A methodological approach

The dynamics of fog droplets depend on their size and chemical composition as well on the ambient conditions such as relative humidity (RH) and turbulence. We analyze the droplet size distribution (DSD) in clouds and fog and how it covaries with the air humidity. We developed a new setup to remove fog droplets from the foggy air in order to quantify RH in the droplet-free air. The setup consists of a newly developed fog droplet separator with an attached H2O gas analyzer and precision thermometer. The fog droplet separator works similarly to an active fog collector, yet with a high collection efficiency of 98.4% for the liquid water content. The water vapor concentration and the air temperature are measured in the droplet-free air at a frequency of 1 Hz. Using this system and a FM100 Fog Monitor, we analyzed the droplet size distribution (DSD) and studied how it covaries with RH.We examined two long-lasting fog events in March and April 2017 on Mt. Lulin, Taiwan. We found that the DSD differed between data with high RH (>100.3%) and low RH (<99.7%). For one event, we were able to confirm the hypothesis of the Köhler theory, which states that droplets are smaller at a low RH than at a high RH. In the other event, the droplets were larger at low RH, which was caused either by entrainment of air masses of different compositions or by droplet growth from below the detection limit to a detectable droplet size, or by a decrease of droplet sizes beyond the critical diameter with decreasing RH. The results show that the developed setup is appropriate to analyze how the DSD covaries with RH in fog.

Optimizing the Performance of Electroplating Gas-Cleaning Equipment

Electroplating industry has by-products, most of which are harmful. The paper considers the issue of removing aerosol emissions during chrome coating. We developed a droplet separator, which was granted a patent for a useful model. Based on the model, we proposed a stage-by-stage technical procedure for cleaning gas-air mixture to optimize the performance of gas-cleaning equipment during hard chrome coating. We calculated the amounts of water vapor and chromic anhydride which is released during chrome plating without cleaning and when using the developed procedure for gas mixture cleaning. We determined maximum surface concentrations of pollutants in exhaust gases after cleaning.

Preparation and characterization of spray-dried submicron particles for pharmaceutical application

The versatile use of submicron-sized particles (0.1–1 μm) requires new manufacturing methods. One possibility for the preparation of submicron-sized particles is spray drying. However, the generation of small droplets at a high production rate and the precipitation of submicron particles are quite challenging. In order to produce a sufficient amount of fine and uniform droplets, a two-fluid nozzle with internal mixing was combined with a cyclone droplet separator. The precipitation of particles was realized with an electrostatic precipitator. Considering the difficulty of electrostatic precipitation concerning explosion risks and to make it capable using organic solvents, the spray dryer was integrated in a pressure resistant vessel. Based on previous experiments, the now presented design is compact and the electrostatic precipitator is shortened. In addition, enhanced drying conditions ensured a controlled and reproducible preparation of submicron-sized particles. Thus, high separation efficiencies were shown. Spray-drying experiments were conducted with the model substance mannitol. With the cyclone droplet separator, a fine and uniform spray with a droplet size smaller 2 μm was produced. This robust atomizing technique is capable for high concentrations. For a 10 wt% mannitol solution, particles in the submicron range d50,3 = 0.7 μm were produced.

Preparation of spray dried submicron particles: Part A – Particle generation by aerosol conditioning

The preparation of submicron-sized particles is relevant in chemical, food and pharmaceutical applications. In pharmaceutics, spray dried submicron-sized particles (0.1–1 µm) can increase the dissolution rate as well as the solubility of poorly water-soluble drugs. Since the particle size during spray drying is mainly influenced by the droplet size, the preparation of uniform droplets smaller than 3 µm is of particular interest. In this work, a two-fluid nozzle was combined with a cyclone droplet separator. Droplets larger than the cut-off size were separated with a cyclone droplet separator and returned to the liquid feed. The aerosol at the outlet of the droplet separator was subsequently dried. The drop size of the conditioned aerosol was small, d50,3=2 µm, and independent of the liquid-to-gas mass flow ratio and the viscosity of the liquid feed. Thus it only depended on the characteristics of the separator. Finally, the dried particles were spherical in shape and in the submicron-sized range.

The Experimental Investigation of Scroll Expanders Operating in the ORC System with HFE7100 as a Working Medium

The paper presents the results of experimental investigation on the ORC system with a droplet separator (which was used to improve the quality of working medium vapour) and two scroll expanders, which operated individually. The research aimed at verifying the correctness of scroll expanders performance in the ORC installation, equipped with the electric flow heater for thermal oil as a heat source. The paper contains the characteristics of the heat exchangers installation that were obtained for the ORC system variant using a regenerative cycle. The tests were conducted for selected flow rates and various temperatures of the working medium HFE7100, glycol solution and thermal oil. The unit with a gear pump and a magnetic coupling functioned as a circulating pump. Following the results of tests carried out on two scroll expanders it may be concluded that the electric power output that was measured at the generator terminals was approximately 750 W. The maximum voltages generated by the expanders amounted to around 200 V and the maximum current was about 4 A.

The Experimental Investigation of the Biomass-Fired ORC System with a Radial Microturbine

The paper presents the results of experimental investigation of the ORC system with a droplet separator (which was used to improve the quality of working medium vapour), a radial microturbine and a multi-fuel boiler. The research aimed at verifying the correctness of prototype microturbine performance in the ORC installation, equipped with a heat source in the form of the multi-fuel boiler. During these tests, a detailed assessment of the functioning of the microturbine and the boiler has been devoted more attention. The paper contains the characteristics of the heat exchangers installation that were obtained for the ORC system variant using a regenerative cycle. The multi-fuel boiler was fired with biomass (wood pellets). Two series of measurements were conducted for various flow rates and several selected temperatures of the working medium, glycol solution and thermal oil. On the basis of research carried out on the ORC with a radial microturbine, one can say that, physicochemical parameters of the HFE7100 medium obtained during the first measuring series, were as follows: temperature at the microturbine inlet 158.9 °C, pressure at the microturbine inlet 9.66 bar, flow rate 178.9 g/s at the microturbine discharge pressure of 1.75 bar. The second series of measurements gave the following results: temperature at the microturbine inlet 163.2 °C, pressure at the microturbine inlet 9.86 bar, flow rate 179.2 g/s at the microturbine discharge pressure of 1.88 bar. The maximum electrical power generated with the use of radial microturbine working in the regenerative ORC system reached about 1150 We.

One-step fabrication of 3D silver paste electrodes into microfluidic devices for enhanced droplet-based cell sorting

3D microelectrodes are one-step fabricated into a microfluidic droplet separator by filling conductive silver paste into PDMS microchambers. The advantages of 3D silver paste electrodes in promoting droplet sorting accuracy are systematically demonstrated by theoretical calculation, numerical simulation and experimental validation. The employment of 3D electrodes also helps to decrease the droplet sorting voltage, guaranteeing that cells encapsulated in droplets undergo chip-based sorting processes are at better metabolic status for further potential cellular assays. At last, target droplet containing single cell are selectively sorted out from others by an appropriate electric pulse. This method provides a simple and inexpensive alternative to fabricate 3D electrodes, and it is expected our 3D electrode-integrated microfluidic droplet separator platform can be widely used in single cell operation and analysis.

Experimental investigation of the ORC system in a cogenerative domestic power plant with a scroll expanders

Abstract The paper presents the results of experimental investigations of the ORC system with two scroll expanders which have been used as a source of electricity. Theworking fluidwas HFE7100 – a newly engineered fluid with a unique heat transfer and favourable environmental properties. In the ORC system three heat exchangers were used (evaporator, regenerator, condenser) and before expanders the droplet separator was installed. As a source of heat an innovative biomass boiler was used. Studies have been carried out for the expanders worked in series and in parallel. The paper presents the thermal and fluidflow properties of the ORC installation for the selected flow rates and different temperatures of the working medium. The characteristics of output electrical power, operating speed and vibrations for scroll expanders were also presented.

SPRAY PYROLYSIS OF MANGANESE DOPED ZINC SILICATE PHOSPHOR PARTICLES

Spherical-shape Zn 2 SiO 4: Mn phosphor particles with the mean particle size from submicron to micron sizes were prepared by ultrasonic spray pyrolysis method. A droplet separator was introduced to control the size distribution of the phosphor particles with spherical shape. The Zn 2 SiO 4: Mn phosphor particles with 2 mol% doping concentration of manganese have decay time and have photoluminescence intensities comparable with those of the latest commercial product prepared by the solid state reaction method. The size of the phosphor particles was decreased from 1000 to 200 nm as the inorganic salt solution concentration was changed from 0 to 5 M. The phosphor particles prepared from the solutions above 0.5 M have photoluminescence intensities comparable with that of the latest commercial product.

분무 열 분해법을 이용한 Zn2SiO4: Mn 나노 형광체의 광학적 특성에 관한 연구

PDP를 비롯한 형광체를 이용하는 디스플레이 분야에서 현재 마이크로미터(<TEX>$\mu}$</TEX>-meter) 이상의 크기를 갖는 기존의 벌크(bulk) 형광체를 능가하는 성능과 새로운 물성을 나타내는 나노형광체(nanophosphor) 개발 및 응용에 대한 연구가 절대적으로 필요한 시점이다. 따라서 본 실험에서는 나노 사이즈의 평균 입자 크기를 갖는 구형의 <TEX>$Zn_2SiO_4:Mn$</TEX> 형광체 입자를 초음파 분무열 분해(ultrasonic spray pyrolysis) 방법을 이용하여 합성하였다. 구형의 형광체 입자의 크기는 분무 장치의 droplet separator를 도입하여 조절하였다. 2 mol%의 망간을 도핑하여 합성한 <TEX>$Zn_2SiO_4:Mn$</TEX> 입자는 시간이 지남에 따라 감소되고, 최근에 고상에서 합성하여 상용화된 물질에 비교할 수 있을 만한 빛 방출의 세기를 가졌다. 형광체 입자의 크기는 무기질 염의 농도가 0에서 5 M로 증가함에 따라 <TEX>$1\;{\mu}m$</TEX>에서 <TEX>$0.2\;{\mu}m$</TEX>로 감소하였다. 0.5 M 이상의 농도의 전구체 용액에서 얻어진 형광체 입자의 빛 방출은 상용화되어 있는 물질과의 비교를 통해 알아보았다. Spherical shape <TEX>$Zn_2SiO_4:Mn$</TEX> phosphor particles with the mean particle size from submicron to micron sizes were prepared by ultrasonic spray pyrolysis method. A droplet separator was introduced to control the size distribution of the phosphor particles with spherical shape. The <TEX>$Zn_2SiO_4:Mn$</TEX> phosphor particles with 2 mol% doping concentration of manganese have decay time and have photoluminescence intensities comparable with those of the latest commercial product prepared by the solid state reaction method. The size of the phosphor particles was decreased from 1 to 0.2 micrometers as the inorganic salt solution concentration was changed from 0 to 5 M. The phosphor particles prepared from the solutions above 0.5 M have photoluminescence intensities comparable with that of the latest commercial product.

Phosphor layer formed from the Zn 2SiO 4:Mn phosphor particles with spherical shape and fine size

Spherical-shape Zn 2SiO 4:Mn phosphor particles with the mean particle size from submicron to micron sizes were prepared by ultrasonic spray pyrolysis. A droplet separator was introduced to control the size distribution of the phosphor particles with spherical shape. The Zn 2SiO 4:Mn phosphor particles with 13 mol% doping concentration of manganese have decay time and have photoluminescence intensities comparable with those of the latest commercial product prepared by the solid state reaction method. All the phosphor particles prepared from the solution above 0.2 M have spherical shape and non-aggregation characteristics at the optimized post-treatment conditions for the maximum photoluminescence intensity. The size of the phosphor particles was increased from 0.65 to 1.25 μm as the solution concentration was changed from 0.2 to 2 M. The phosphor particles prepared from the solutions above 0.2 M have photoluminescence intensities comparable with that of the latest commercial product. The phosphor layer formed using the phosphor particles with spherical shape and fine size (1 μm) have uniform surface and dense structure. While the phosphor layer formed using the latest commercial product has rough surface morphology and coarse structure.

The potential to reduce emissions of airborne microorganisms by means of biological waste gas treatment systems

Investigations regarding the reduction of airborne germs in the waste gas of biowaste composting processes have been carried out at the Hamburg University of Science and Technology and the University of Leipzig. Numerous waste gas treatment plants, ranging from laboratory-scale to technical-scale, have been available at the institutes of these two project partners. All plants consisted of bioscrubber/biofilter combinations. The results showed that these biological systems designed for odour control are able to successfully reduce bioaerosol emissions, even though a reduction to background levels could not be achieved. The bioscrubber, if equipped with a droplet separator, proved to be mainly responsible for the reduction, whereas the biofilter acted as a source for microbial emissions originating from the filter material. It could be observed that the microbial population changed while passing the treatment system, indicating the ability of biological waste gas treatment systems to retain potentially pathogenic microorganisms from waste gases.

The cyclone scrubber – a high efficiency wet separator

AbstractDue to induced turbulent interactions between particles to be separated and the scrubbing liquid present as droplets, very good collection efficiency down to submicron particle size can be achieved as shown by detailed studies [1]. Assumed are suitable flow conditions, a long residence time and a certain droplet size distribution or a special liquid dispersion system. As the name implies, the cyclone scrubber basically consists of a cyclone. This cyclone serves as a contact space in which the interaction between dust particles and scrubbing liquid droplets takes place, and as a droplet separator. Thus, under normal conditions, a water saturated but dust‐ and droplet‐free gas stream leaves the cyclone. The droplets are generated by a pneumatic atomization nozzle, arranged at the cyclone inlet in the direction of flow. A complete theoretical description of the three‐dimensional, three‐phase, non‐steady turbulent flow in the cyclone scrubber has not been possible up to now. The detailed experimental investigations presented in this work, and covering multiple parameters, led to physically based conclusions about the dominant interactions and separation mechanisms involved. Grade efficiencies which did not fall below 0.75, down to a particle size of 0.5 μm, could be measured by an optical particle counter. Collection efficiency of 99.2% was determined by gravimetric analysis of the dust load, according to VDI‐guideline 2066, in the raw and clean gas sections of the dust load, according to VDI‐guideline 2066, in the raw and clean gas sections of the cyclone scrubber.

Design of a Spinning Disc, Droplet Separator and the Determination of the Size and Density of Droplets Deposited on Cotton Foliage

Design of a Spinning Disc, Droplet Separator and the Determination of the Size and Density of Droplets Deposited on Cotton Foliage