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The main goal of this study was to evaluate the performance of the biomass gasifier stove used to bake injera using Eucalyptus Globulus wood fuel as a feedstock. Its performance was affected by the wood fuel's physical and thermal properties; like particle size, biochar yield, burning rate, syngas composition, and tar content. The height and diameter of the designed gasifier stove were settled to be 50 cm and 40 cm, respectively. The gasifier stove's temperature range for gasification was 657 to 840 °C at 100% grate opening. Standard Control Cooking Test (CCT) procedures were used to evaluate the gasifier stove's performance. The largest increase in biochar yield (12% to 19.8%) was obtained by varying biomass particle size from 8 to 30 mm; however, larger particles also triggered tar generation, which peaked at 93 g/m3 syngas at 30-mm biomass particles; in contrast, the hydrogen content and CO composition in syngas was at its lowest at this condition, 2.89% and 11.82%, respectively. The amount of tar present in the syngas was negatively correlated with the combustion temperature. The calorific value in the syngas was at its minimum of 2.72 MJ/m3. Using 8 mm-sized particles, a maximum combustion temperature of 840 °C was attained. The burning time in the reactor using 6 kg of fuel was 26 min. Results showed that heated air is more fuel-efficient for gasification and effective for reducing baking time. The Control Cooking Test indicated that the new gasifier reduces baking time and fuel usage by 32% and 50%, respectively, when compared to an open-fire three stone stove. [ABSTRACT FROM AUTHOR]

In this study, the effect of combination of twisted tape turbulator and air injection on heat transfer augmentation is studied. The air injection as the active method and the twisted tape turbulator as the passive method were used simultaneously to increase the heat transfer rate. The rate of air flow as like to pitch of twisted tape tabulator was considered as the variants. Six different air flow rates were considered in this study which provides a superficial gas Re number range of 147.07–882.30. Also the superficial liquid Re number had the range of 2400–6000. For the twisted tape, three different twisted tapes with twist ratio (λ) of 11.66, 6.66 and 5 were considered to check the effect of twist ratio on the thermo-hydraulic properties of the considered tube. A horizontal copper-made tube was considered as the test section which was under constant heat flux. In order to better understanding the flow structure, the flow structure was captured via a Canon SX540 camera. Flow patterns, heat transfer coefficient, pressure loss and C.B.R (cost per benefit ratio) were the variants that were probed in the present paper. It was found that the presence of the twisted tape turbulator could significantly affect the flow structure of the two-phase flow. The flow maps presented that by the decrement of twisted tape pitch the transition of slug flow to bubbly flow occurs very soon. Also, by the decrement of twisted pitch a swirling bubbly flow was observed in the horizontal tube. The maximum increment in the Nusselt number and pressure loss was about 35% and 81%, respectively. Also, it was revealed that for the water superficial Re number of more than 2400 with the decrement of pitch of twisted tape turbulator, the amount of C.B.R factor decreases. [ABSTRACT FROM AUTHOR]

At thermal power stations, the rate of the fuel equivalent consumed to generate electric energy, the vacuum level in condensers, and the steam turbine output are determined by the performance of the cooling towers. However, the occurrence of water and air flows' nonuniform distribution may become one of the causes of a reduction in the cooling towers' efficiency. Research into the aerodynamic characteristics of a chimney-type cooling tower under the nonuniform distribution of the water and air flows over the cells of the apparatus has been conducted. The effects of four factors, viz., the drop of the atmospheric air and cooling water temperatures, the hydrodynamic resistance coefficient of a cell, the water concentration in the latter, and the wind velocity in close proximity of the air-intake ports, on the consumption rate of the intake air and its distribution over the cooling tower cells have been analyzed. The effect of the water concentration on the distribution of the air over the cooling tower cells has been studied under laboratory and field conditions. The existence of a correlation relationship between the above parameters has been established. In the course of the experiments, the extreme form of dependence of the wind velocity distribution over the cooling tower cells on the wind velocity field in the vicinity of the air-intake ports has been obtained. The effect of every factor on the air velocity in individual cells and the cooling tower as a whole has been analyzed. Based on the experimental results, both one-dimensional regression equations and a multiple regression equation for all factors have been derived. [ABSTRACT FROM AUTHOR]

Abstract—A winter bee community of 15 000 bees housed in wooden beehive boxes with 12 frames was used to analyze the physical processes that occur in beehives. The most important specific feature of this study is assessment of the changes in the size of the bee cluster during overwintering and the relationship between temperature, humidity, and air flows in the beehive. The physical processes in hives were simulated using the Comsol 5.3 software package. The temperature fields confirm the high heat insulating ability of bees. The temperature on the external surface of winter cluster was +12°C. Despite the changes in the temperature outside the cluster, the temperature inside it was stably maintained at +25 to +32°C. The inside temperature of the winter cluster was nonuniform, with some local foci of up to but not exceeding +34°C, which is safe for the bees. Analysis of the air flows showed a velocity of 0.03–0.1 m/s at the entrance to the hive and of 0.12–0.17 m/s at the central opening. The highest velocity was recorded inside the cluster (over 0.19 m/s). The moisture distribution in the hive was as follows: the moisture content in the incoming air was 0.04 mol/m3 and in the outgoing air it was 0.5–0.6 mol/m3, which is explainable by elimination of the moistened air from the bee cluster. The images of the moisture distribution in hive elements prove the agreement between the saturation rate of wooden walls and the humidity of the boundary air. [ABSTRACT FROM AUTHOR]

A device is developed for loading granular materials by shearing with air flow driven through the material without its pseudo-liquefaction. Internal stresses and dilatancy of a sample are measured depending on shearing angle. It is shown that shear modulus, characterizing material capability to resist shearing as air flow rate is increased, lowers while dilatancy grows. [ABSTRACT FROM AUTHOR]

Regenerator is major component of liquid desiccant regeneration system. The influence of operating parameters; air flow rate, solution flow rate and concentration of desiccant is investigated experimentaly on the performance parameters; outlet specific humidity, evaporation rate, air outlet temperature, mass transfer coefficient and effectiveness of the regenerator. Air and desiccant solution flow in counter direction with celdek pads as packing material. It is concluded that evaporation rate increases with increasing solution temperature, air flow rate and solution flow rate whereas same decreases with increasing concentration of desiccant. The effectiveness of regenerator is increased by 99 % with increase in air flow rate. A comparison of present finding with those available in the literature is presented in the last. Simulation results have revealed good agreement between the present experimental results. [ABSTRACT FROM AUTHOR]

Coal is primarily beneficiated by wet gravity methods. The wet processing of coal is an efficient practice. However, it introduces the moisture in the range of 6%-15%, depending upon the size of coal which is as detrimental as ash content to the heating value of coal. Dry beneficiation of coal fines was carried out using an air fluidized vibrating table in which the coal particles get separated from the heavier mineral particles as a result of horizontal and vertical stratification. Two level factorial design matrix was used to optimize and assess the interactive effects of the operational parameters of a pneumatic table viz. deck eccentric, side tilt and air flow rate on the clean coal yield and its ash content. Double stage processing was found to be more effective for reducing the ash content of the clean coal. Initial stage of processing at a higher ash level generates a reject of high ash with low combustibles. Cleaning of the rougher concentrate at 34%-35% ash level shows significant improvement in the organic efficiency (88.6%) and useful heat value of clean coal (15690 kJ/kg). The performance of air fluidized vibrating deck was measured by E value which is 0.18. [ABSTRACT FROM AUTHOR]

This paper is aimed to introduce and validate a gene expression programming (GEP) model to estimate the rate of air flow in triaxial conditions at various confining pressures incorporating cell pressure, air inlet pressure and air outlet pressure. To achieve the aim of this study, a series of laboratory experiments were designed and carried out and then a database comprising 47 datasets was prepared to develop new predictive models. A gene expression programming (GEP) model for prediction of air flow was proposed using the prepared datasets. In this regard, a series of sensitivity analyses were performed to choose the best GEP model. For comparison purposes, multiple regression (MR) analysis was also employed for air flow estimation. Several performance indices, i.e., coefficient of determination (CoD), mean absolute error (MAE), root mean square error (RMSE) and variance account for (VAF) were considered and calculated to evaluate the performance prediction of the developed models. Considering both training and testing datasets, the developed GEP model can provide higher performance prediction of rate of air flow in comparison to the MR model. [ABSTRACT FROM AUTHOR]

Results are presented from studies of the intensive radial injection of an air blast into a crucible to recycle electronic scrap. A relation is found to describe the effect of the blast and the unsubmerged air jet on mass transfer, and an empirical formula is obtained to calculate the unit air flow rate in the critical regime. [ABSTRACT FROM AUTHOR]

Results are provided for a study of the creation of ceramic materials for aerator nozzles. The effect of porous ceramic pore size and air bubbles emerging from it are considered. Physicotechnical properties of porous permeable material specimens for aerator nozzles are provided. An experiment is performed for determining the effect of air flow rate, effective pore size and specimen thickness on the oxygen content in water. Production of the inserts developed is organized. [ABSTRACT FROM AUTHOR]

A triboelectrostatic separation system using a fluidized-bed tribocharger for the removal of PVC material in the mixture of PVC/PET plastics was designed and evaluated as a function of tribocharger material, air flow rate, electric field strength, and the mixing ratio of two-component mixed plastics. The test system consists of the fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PET particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the tribocharger material, electric field strength and particles mixing ratio. In the optimum conditions of 150 l/m air flow rate and 2.6 kV/cm electric field strength, highly concentrated PVC (99.1%) can be recovered with a yield of more than 95% from the mixture of PVC and PET materials for a single stage of processing. [ABSTRACT FROM AUTHOR]

A triboelectrostatic separation system using a fluidized bed tribocharger for the removal of PVC material in the mixture of PVC/PS plastics is designed and evaluated as a function of electric field strength, air flow rate, and the mixing ratio of two- component mixed plastics. It consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PS particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the electric field strength and particle mixing ratio. In the optimum conditions of 150 lpm air flow rate and 2.6 kV/cm electric field strength a highly concentrated PVC (99.1%) can be recovered with a yield of more than 99.2% from the mixture of PVC and PS materials for a single stage of processing. [ABSTRACT FROM AUTHOR]

An instrumentation and automation system for a side-vented pan coater with a novel air-flow rate measurement system for monitoring the film-coating process of tablets was designed and tested. The instrumented coating system was tested and validated by film-coating over 20 pilot-scale batches of tablets with aqueous-based hydroxypropyl methylcellulose (HPMC). Thirteen different process parameters were continuously measured and monitored, and the most significant ones were logged for analysis. Laser profilometry was used to measure the surface roughness of the coated tablets. The instrumentation system provided comprehensive and quantitative information on the process parameters monitored. The measured process parameters and the responses of the film-coated tablet batches showed that the coating process is reproducible. The inlet air-flow rate influenced the coating process and the subsequent quality of the coated tablets. Increasing the inlet flow rate accelerated the drying of the tablet surface. At high inlet flow rate, obvious film-coating defects (ie, unacceptable surface roughness of the coated tablets) were observed and the loss of coating material increased. The instrumented and automated pancoating system described, including historical data storage capability and a novel air-flow measurement system, is a useful tool for controlling and characterizing the tablet film-coating process. Monitoring of critical process parameters increases the overall coating process efficiency and predictability. [ABSTRACT FROM AUTHOR]

A heat balance was performed on a 25 L jacketed continuous stirred tank reactor used for the production of single cell protein from cheese whey using Kluyveromyces fragilis under three levels of retention time (12, 18, and 24 h), two levels of air flow rate (1 and 3 VVM), and three levels of mixing speed (200, 400, and 600 RPM) to determine the heat of reaction and the portions of lactose used for energy and growth as well as to assess the need for the cooling system. The yeast population size, oxygen concentration, and lactose concentration in the reactor as well as the portions of lactose used for energy and growth were all affected by the hydraulic retention time, mixing speed, and air flow rate. About 8-14% of lactose was utilized for energy and 86-92% was utilized for growth. The highest cell number was obtained at the 12 h retention time, 3 VVM air flow rate, and 600 RPM mixing speed. Under these conditions, the lactose removal efficiency was 95.6% and the yeast yield was 0.78 g cell/g lactose removed. [ABSTRACT FROM AUTHOR]