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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]

Photocatalytic degradation of diclofenac, an anti-inflammatory drug, was investigated with TiO2 photocatalyst under UV light (365nm). The effects of photocatalyst concentrations (0.5 g/L, 1 g/L and 2 g/L) and air flow rates (3L/h, 6 L/h, 12 L/h and 18 L/h) on photodegradation kinetic were evaluated for 15 mg/L diclofenac solution during 4 hours. The results showed that the amount of TiO2 and air flow rates have direct influence on the photocatalytic degradation of diclofenac. Excessive catalyst amount and high air flow rates inhibited the degradation of diclofenac. The highest diclofenac degradation efficiency of 78.4 % were achieved by 6 L/h air flow rate with a photocatalyst concentration of 0.5 g/L. The photocatalytic degradation of diclofenac followed the Langmuir-Hinshelwood kinetic model except the experiments carried without air flow and very low air flow rates. [ABSTRACT FROM AUTHOR]

Introduction. The influence of atrium on temperature stratification under indoor natural ventilation of the teaching-laboratory building of the Moscow State University of Civil Engineering (MGSU) with the help of full-scale experiments is considered. Based on this, the aim of the research is to develop a new method of calculating the optimal geometric parameters of a building atrium considering the comfort of its temperature-air regime by solving the developed basic airflow equations in combination with mathematical modelling methods. The formula for determining the air flow rate for natural ventilation in atriums, analyzing and designing a natural ventilation system in a building with an atrium with more than two ventilation outlets was derived. Based on the results obtained, a conclusion is made about the optimal area of exhaust and supply openings in an atrium building at different heights. These data may have practical application in the design of buildings with atriums.Materials and methods. Semi-empirical research methods were used. Simple linear regression methods were carried out to establish a correlation between the measured variables air temperature and building construction height in an atrium with specific conditions to determine the temperature at any height.Results. The formula for calculating the optimal area of inlet and outlet openings in connection with the atrium height and their influence on the thermal characteristics of the structures of buildings with atriums was developed.Conclusions. The results of the research make it possible to quickly and accurately determine the geometric parameters to ensure the reduction of air temperature in buildings with atriums. This plays an important role in the initial design phase.

Lubrication and cooling in hard machining is an urgent and growing concern. The use of a suitable cooling lubrication condition is a crucial factor and has a great influence on the machining efficiency and the machined surface quality in hard machining. Among the proposed technological solutions, minimum quantity lubrication (MQL) using nano-cutting oils is a novel solution and its effectiveness has been proven for hard turning. This work aims to investigate the influence of MQL technological parameters using MoS2 nano-cutting oil including nanoparticle concentration, air pressure, and air flow rate on surface roughness and the resultant cutting force in hard turning using CBN inserts. Box-Behnken optimal experimental design and ANOVA analysis were used to study the influence of the input parameters and determine the optimal values. The results present the influence of the survey parameters and provide technological guides for specific objective functions for further sustainable studies on MQL hard turning using nano-cutting oil. [ABSTRACT FROM AUTHOR]

Aim: The aim of this article is to evaluate the effect of selected positioning parameters of the fan (positioning distance and impeller angle) on the ability to pump a volumetric airflow stream through a construction object. Project and methods: Mobilne wentylatory wykorzystywane podczas działań ratowniczych stanowią ważne narzędzie pozwalające ograniczyć rozprzestrzenianie się dymu podczas pożarów wewnętrznych obiektów budowlanych. Z uwagi na charakter wykorzystania tych urządzeń, cechy warunkujące ich skuteczność działania powinny być poddane badaniom z wykorzystaniem metodyk badawczych o charakterystyce zbliżonej do ich rzeczywistych warunków stosowania. W artykule przedstawiono autorską metodę badań objętościowego strumienia przepływu powietrza. Ponadto zaprezentowane zostało stanowisko badawcze FRC (ang. flow resisting curtain) przeznaczone do wyznaczania charakterystyk przepływowych w rzeczywistych układach obiektów budowlanych. Badania przepływowe wykonano na terenie obiektu o kubaturze 282 m3 stanowiącego salę szkoleniową Centrum Naukowo- -Badawczego Ochrony Przeciwpożarowej – Państwowego Instytutu Badawczego. Methodology: Mobile fans used during rescue operations are an important tool to reduce the spread of smoke during interior fires in buildings. Due to the nature of the use of these devices, the characteristics that determine their performance should be tested using test methodologies with characteristics similar to their actual conditions of use. The article presents the author's method for studying the volumetric flow rate of air. In addition, a flow resisting curtain (FRC) test stand for determining flow characteristics in real building systems was presented. The flow tests were carried out at a facility with a volume of 282 m3, which is a training room of the Scientific and Research Centre for Fire Protection – National Research Institute. Results: As part of the performed research, the flow characteristics for the mobile fan sample were determined. The completed tests showed that the fan pumped a volumetric flow rate ranging from 2471 to 17997 m3/h. It was determined that the most favourable positioning distance of the tested fan calculated from the inlet opening to the room is 5 meters. At this distance, the highest values of volumetric flow rate were obtained for both studied slope angles – 0 and 8° (recorded values are 17298 and 17997 m3/h, respectively). Conclusions: Proper positioning of the mobile fan has a significant impact on the amount of airflow pumped through the building. The positioning parameters of the mobile unit are, respectively, the mechanism for changing the angle of the air supply and its mobility – the ability to move to another location. This article presents the results of a test of the volumetric flow characteristics of an air jet generated by a mobile fan. The test results showed that the parameters of fan positioning have a significant impact on the effectiveness of tactical mechanical ventilation during rescue operations. Observations made during the tests indicate that it is reasonable to implement requirements for the mandatory use of information boards showing the optimal positioning parameters for mobile units to achieve the highest possible expenditure. Keywords: Positive Pressure Ventilator (PPV), mobile fan, full scale experiment, open flow, air flow rate

This experimental study aims to investigate the effect of the closed cycle of air circulation on the thermal performance of the solar air collector with attached fins in the site of Laghouat in Algeria, under climatic conditions. Our experimental procedure includes two types of cycles: open cycle and closed cycle. For each cycle, we have considered two tilt angle: 0 and 30 degree. Moreover, the solar collector is oriented in a southerly direction with a definite angle of inclination. The flow rate used in experiment is equal to 0.0129402 m3/s. Then, by comparing the experimental and theoretical results, we observe that the maximum temperature difference between the outlet and inlet air for the open cycle (27 °C, at 14h30) is higher than that of the close cycle (17 °C, at 14h00). The maximum efficiencies obtained for the open cycle for the both configurations were η (30 degrees) = 25.29 % and η (0 degree) = 35.71 % at 4 pm. These values are higher than those of the maximum efficiencies of the closed cycle with η (30 degrees) = 7.86 % at 4 pm and η (0 degree) = 13.31% at 12h00, respectively

In recent years, more efficient hard machining processes have notably increased in demand for higher productivity but environmental friendliness. High hardness and strength as well as the enormous amount of cutting temperature are still the biggest obstacles. Nanofluid minimum quantity lubrication (NFMQL)–assisted hard machining has become a feasible and promising solution to overcome these problems. The work presents the experimental study on the effects of air pressure (5, 6, and 7 bar), air flow rate (150, 200, and 250 L/min), and Al2O3 nanoparticle concentration (0.5, 1.0, and 1.5%) on minimum quantity lubrication (MQL) hard milling process of 60Si2Mn (50÷52HRC) using vegetable oil as the based fluid. Box–Behnken experimental design and ANOVA analysis were employed to investigate the influences and interaction effects of input parameters on cutting forces, surface roughness, and surface microstructure. This study will be used for selecting the optimum air pressure, air flow rate, and Al2O3 nanoparticle concentration for efficient cooling lubrication performance of MQL in sustainable hard machining. The obtained results show that the optimal values for air pressure and nanoparticle concentration. For Q = 200 L/min, the optimal p is 6.0 bar and the optimal nanoparticle concentration (NC) is 0.9%. For Q = 250 L/min, the optimal p is 5.2 bar, and the optimal NC is 1.2%. Furthermore, using air flow rate Q = 250 L/min gives better results than Q = 200 L/min, but the selection will be depended on the specific equipment conditions. [ABSTRACT FROM AUTHOR]

This research work incorporates experimental investigation and simulation to inspect the impact of influential parameters on the efficiency of a forced draft cooling tower. The number of packing ribs, the flow rate of water, the flow rate of air, the surface area, and the area of contact are the parameters investigated in this study. All of these parameters are altered and their effect on efficiency is explored. Two types of packing with varying rib numbers of packing and areas are utilized to observe their influence on the efficiency of the cooling tower. Modeling and CFD analysis of the aforementioned cooling tower is done on SOLIDWORKS and ANSYS Fluent respectively. Finally, the results from experimental data and CFD analysis are compared to inspect the effectiveness of the simulation. The results depicted that the efficiency of a forced draft cooling tower varies directly with the flow rate of air and inversely with the flow rate of water. Moreover, the performance of the cooling tower has a direct relationship with the area of contact, time of contact between air and water, and the number of ribs. The results obtained from CFD analysis are compared and validated with experimental results. Finally, percentage error analysis is also presented between simulation model efficiency and experimentation efficiency of the benchtop cooling tower and it exhibits good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Increasing the production of liquid smoke is an attempt to raise the utilization of coconut shells as a by-product of the coconut fruit. The distillation process is a way to produce liquid smoke and condensation occured in the cooling bath. Improving the cooling bath can increase the production volume. This study aims to determine the performance of the cooling bath in 10 experiments with variations in the level of the water flow rate factor of 20 liters/minute, 25 liters/minute, 30 liters/minute, and the level of the airflow velocity factor of 35 m/s, 40 m/s. and 45 m/s. Modifying the cooling bath can improve its performance and increase the volume of liquid smoke. The largest increase of 36.14% was achieved at the water flow rate in the level of 30 liters/minute and the airflow velocity factor in the level of 45 m/s, at 26.2oC of the cooling bath temperature.

The air flow induced by a water jet freely falling inside a vertical pipe with its top and bottom both open to the atmosphere was investigated experimentally and numerically. In the experiments, the radial air velocity distribution and the air pressure variation along the vertical pipe were measured. The air drag of the falling water jet was related to the jet surface disturbance and analyzed by introducing the equivalent friction factor. A predictive model was developed for the air flow inside a 3-m-high pipe based on the momentum equation and its results compared well with the experimental measurements. Numerical simulations were also conducted by approximating the free-falling water jet as a continuous moving solid with diameter and velocity varying in the direction of motion. The effects of pipe size on the air velocity profile and the induced air flow rate were examined. The simulation results showed that the streamwise air velocity profiles inside pipes of different sizes approached the same after a certain traveling distance. The maximum induced air flow rate was found at the pipe diameter of about 20 times of initial water jet diameter. [ABSTRACT FROM AUTHOR]

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The growth of environmental and economic requirements for the performance properties of internal combustion engines makes it necessary to constantly improve them. One of the ways to improve the design of engines is to improve the performance of its cooling system, which determines the stability of its thermal regime, on which the engine life and performance indicators directly depend. To increase the efficiency of the cooling system, you can increase the speed of the air flow flowing through the radiator and created by the fan. Flow velocity can be increased by reducing the aerodynamic drag in the air path of the engine cooling system. To do this, you need to know the actual distribution of air flow velocities in front of the radiator at its various points. The purpose of this work was to experimentally determine the air flow rates in front of the radiator at its various points at different values of the supply voltage. In accordance with the developed research methodology, a laboratory installation was developed that allows you to place the radiator assembly with the fan unit and determine the speed of the air flow in front of it with reference to its specific points, measure the speed of rotation of the fan blades and the power consumed by its engine. As a result of experimental studies, approximating response surfaces were constructed that describe the distribution of air flow velocities in front of the radiator at different values of the supply voltage, and the influence of the supply voltage values on the change in the amount of power consumed by the fan motor was established. As a result of the analysis of the data obtained, it was found that a slight decrease in voltage does not reduce the blowing area, but somewhat reduces the air flow rate, which can negatively affect the cooling of the engine itself by the air flow coming out of the fan. The scientific novelty of this work is the experimentally obtained distributions of the values of the air flow velocity in front of the radiator and the research methodology. The research results can be used to improve the efficiency of the fan installation of the engine cooling system. The direction of further research is to study the influence of the resistances at the outlet of the radiator fan casing on the distribution pattern and the air flow velocity.

The process of aerobic biostabilization (AB) has been adopted for treatment of the organic fraction of municipal solid waste (OFMSW). However, thermal gradients and some side effects in the bioreactors present difficulties in optimization of AB. Forced aeration is more effective than natural ventilation of waste piles, but "hot and cold spots" exist due to inhomogeneous distribution of air and heat. This study identified the occurrence of hot and cold spots during the OFMSW biostabilization process at full technical scale. It was shown that the number of hot and cold spots depended on the size of the pile and aeration rate. When the mass of stabilized waste was significantly lower and the aeration rate was two-fold higher the number of anaerobic hot spots decreased, while cold spots increased. In addition, the results indicated that pile construction with sidewalls decreased the number of hot spots. However, channelizing the airflow under similar conditions increased the number of cold spots. Knowledge of the spatial and temporal distribution of process gases can enable optimization and adoption of the OFMSW flow aeration regime. Temperature monitoring within the waste pile enables the operator to eliminate undesirable "hot spots" by modifying the aeration regime and hence improve the overall treatment efficiency. [ABSTRACT FROM AUTHOR]

A homogeneous mixing and drying of food substance are required prior to further processing and storage. This research was carried out to determine the heat transfer parameters of an existing dryer-mixer and evaluate its performance for the drying and mixing of Irvingia gabonensis powder. A 1 kg of the powdered product (~ 15 μm particle size and 24.5% initial moisture content) was dried using the mixer-dryer for 5 hours. The average temperature of the drying chamber was preset at 50oC for the drying process,with the help of a thermostat. The heat transfer parameters, which includes the air flow rate and thickness of wall lagging, were determined mechanistically. Also, the drying performance was determined based on the drying rate, drying efficiency, mixing index, and mixing rate of the machine. Results show that an air flow rate of 0.00082 kgs-1and 0.02 m thickness of a fibre-glass lagging material was required in the drying and mixing operation. Energy required to dry the product from 24.5% (wb) to 12.8% (wb) moisture content was 0.08514 kJ/s at a drying rate of 1.8 kgh-1. A mixing index of 0.819 and efficiency of 82.2 % were obtained, and these may imply effective drying and a high degree of homogenization in the system.

The increase in the cost of fuel for motor vehicles causes not only the search for alternative energy sources and the use of new engine designs for cars, but also the search for ways to reduce fuel consumption in existing cars with an internal combustion engine by improving their design. The power generated by the internal combustion engine is spent not only on the drive of the driving wheels, but also on the drive of auxiliary equipment that provides the ability to operate the engine and its systems, as well as increasing the safety and comfort of movement. By reducing the power to drive the auxiliary equipment or its operating time, it is possible to reduce the fuel consumption of the engine. A mandatory element of any car equipped with an internal combustion engine is the cooling system, which in its composition contains a radiator that provides heat transfer of excess heat to the atmosphere and a fan that intensifies this process if necessary. The operating time of the fan directly affects the fuel consumption of the car engine, therefore, by reducing the operating time of the fan, you can reduce fuel consumption. This can be achieved by increasing the value of the total heat transfer coefficient through the radiator walls, which depends on the speed of air flowing through the radiator. The speed of the air flow, without increasing the power consumed by the fan, can be increased by reducing the aerodynamic resistance of the air path of the car. The theoretical assumptions supported by the analysis of previous studies need experimental confirmation and practical assessment of the amount of fuel economy when improving the air path of the car, which reduces the fan operating time. Purpose – theoretical justification of the influence of the air flow velocity in front of the radiator front on the fuel consumption of the car engine. Methodology the article uses a systematic approach, as well as methods of mathematical modeling. Results: on the example of a particular car, the effect of increasing the air flow velocity in front of the radiator front on the fuel consumption of the car engine is determined. Practical implications the results obtained can be used by organizations engaged in the development, repair and tuning of motor vehicles and their systems.

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]

This study investigates the effect of non-uniform distribution of the air inlet flow rate and change of air flowing direction on the thermal stress of a solid oxide fuel cell stack with cross-flow configuration. This study considers three patterns of air inlet flow rate in the transverse direction of each stack, and five patterns of air inlet flow rate in the stacking direction. The software package for simulation is reliable through an accuracy comparison, and it analyzes the current density, temperature, and thermal stress distribution of a SOFC stack with 20 layers. The results show that the progressively increasing profile of the air inlet flow rate along the x direction drops the cell thermal stress of a SOFC unit. Moreover, the non-uniform profile of air inlet flow rate in the stacking direction affects the position of the region with high thermal stress of the SOFC stack, and changing flow direction of the air obviously drops down the thermal stress without affecting the power generation of the SOFC stack. • Simulate thermal stress analysis of a solid oxide fuel cell stack with the cross-flow. • Investigate different patterns of air flow rate distribution and flow direction. • Effect of air flow rate distribution and flow direction do not affect the power generation. • Changing the air flowing direction effectively improves the thermal stress of a SOFC stack. [ABSTRACT FROM AUTHOR]

• Optimum air flow rates can be predicted for various part load conditions. • Non-iterative simulation model is established for seasonal performance conditions. • A novel dimensionless correlation is developed for heat exchanger effectiveness. • The optimum air flow rate is significant to achieve better seasonal performance. The seasonal performance has become increasingly important for residential heat pumps which occupy a majority of household power consumption. Thus, the heat pump system and its components are requested to be re-designed with reflecting the part load characteristics. Furthermore, actuators should be optimally operated for each test condition to maximize system efficiency. Among them, indoor and outdoor fan speeds are the only variable that can be independently controlled and have the widest operation range. Therefore, in this study, a non-iterative heat pump simulation model is presented to precisely predict the optimum air flow rate for each part load condition by introducing the modified effectiveness. The non-dimensional correlation is developed for the modified effectiveness and semi-empirical efficiency models are utilized for estimating the compressor performance. Validating experiments identify that the model can predict the optimum air flow rate for various part load conditions within an error of 10%. Consequently, the optimum air flow rate can be instantly obtained for various operating conditions. [ABSTRACT FROM AUTHOR]

In this article, a nonthermal gliding arc discharge (GAD) was generated in an air flow driven by a 40-kHz alternating current (ac) constant-current electric power supply. The influence of gas flow rate on the discharge characteristics of gliding arc was investigated using electrical diagnostics and fast Fourier transform (FFT) analysis method. The average discharge power, total harmonic distortion rate of arc voltage (THD ${_{u}}$), total harmonic distortion rate of arc current (THD ${_{i}}$), and the resistance of arc were experimentally studied. As the air flow rate increased from 4 to 12 L/min, it was found that the average discharge power of the gliding arc gradually decreased from 407.9 to 187.8 W. However, because of the nonlinear characteristics of the GAD circuit, with air flow rate increasing, both THDu and THDi linearly increased, while the resistance of arc gradually decreased from 26.3 to 14.1 $\text{k}\Omega $. Totally, the air flow rate influenced the discharge characteristics of the gliding arc mainly by ruling the average discharge power. Finally, for a better understanding of the discharge characteristics of the gliding arc, a discharge circuit model was further analyzed based on the average discharge power and reactive power. [ABSTRACT FROM AUTHOR]

An explicit illustration of pulmonary delivery processes (PDPs) was a prerequisite for the formulation design and optimization of carrier-based DPIs. However, the current evaluation approaches for DPIs could not provide precise investigation of each PDP separately, or the approaches merely used a simplified and idealized model. In the present study, a novel modular modified Sympatec HELOS (MMSH) was developed to fully investigate the mechanism of each PDP separately in real-time. An inhaler device, artificial throat and pre-separator were separately integrated with a Sympatec HELOS. The dispersion and fluidization, transportation, detachment and deposition processes of pulmonary delivery for model DPIs were explored under different flow rates. Moreover, time-sliced measurements were used to monitor the PDPs in real-time. The Next Generation Impactor (NGI) was applied to determine the aerosolization performance of the model DPIs. The release profiles of the drug particles, drug aggregations and carriers were obtained by MMSH in real-time. Each PDP of the DPIs was analyzed in detail. Moreover, a positive correlation was established between the total release amount of drug particles and the fine particle fraction (FPF) values (R2 = 0.9898). The innovative MMSH was successfully developed and was capable of illustrating the PDPs and the mechanism of carrier-based DPIs, providing a theoretical basis for the design and optimization of carrier-based DPIs.

The partial air cushion supported catamaran (PACSCAT) is a novel Surface Effect Ship (SES) and possesses distinctive resistance performance due to the presence of planing bottom. In this paper, the design of PACSCAT and air cushion system are described in detail. Model tests were carried out for Froude numbers ranging from 0.1 to 1.11, the focus is on the influence of air cushion system on resistance characteristics. Drag-reducing effect of air cushion system was proved by means of contrast tests in cuhionborne and non-cushionborne mode. Wave-making characteristics reflect that the PACSCAT would eventually enter planing regime, in which the air could just escape under the seals and the hull body could operate in a steady state. To acquire different air cushion pressure, air flow rate and leakage height were adjusted during tests. Experimental results show that the resistance performance in planing regime would decrease evidently as the increased air flow rate, however, the scheme with medium leakage height presents the best resistance performance in the hump region.

Soil plays an important role in the sustainability of ecosystems. In recent years, the increasing growth in the degradation of soil resources has drawn attention to management strategies for maintaining the soil quality. Researchers have recently studied the impact of using biochar on physical and chemical properties of soil. It has been found that adding biochar improves the soil quality. Some factors such as pyrolysis chamber conditions, pyrolysis peak temperature and air flow rate affect the physical and chemical properties of biochar including the density, pH, ash content, and so on. In this study, the effect of changes in the air flow rate and chamber temperature in the fixed-bed oxidative pyrolysis on the biochar yield, ash content, density and pH were investigated. For this purpose, a fixed-bed biochar production apparatus with varying chamber temperature and flow rate of outlet air was designed and manufactured. The experiments were performed at four air flow rates of 20, 25, 30 and 35 Lmin-1 and four temperatures of 350°C, 400°C, 450°C and 500°C for wheat straw. The results showed that increasing the temperature and flow rate of the outlet air from the chamber increased the ash content and pH. However, increasing these parameters decreased the biochar bulk density and yield. [ABSTRACT FROM AUTHOR]

Solar dryers are not so efficient due to improper control of air flow rate and its temperature. The issue is resolved by developing the hybrid solar dryer which was opted in this study. The experiments were conducted on maize at different drying air temperature (40°C, 45°C and 50°C), air flow rate (300 m3h-1, 400 m3h-1and 500 m3h-1) and drying time (8 h, 12 h and 16 h). The change in moisture content and drying rate were analyzed under different experimental conditions. The reduction in moisture content of maize was better when drying time was increased from 8 h to 12 h, air flow rate from 300 m3h-1 to 400 m3h-1and drying temperature from 40°C to 45°C as compared to further increase in the values of experimental parameters. The similar trend was observed for drying rate. Moreover, the quadratic model developed showed good relationship between predicted and actual response by which hybrid solar dryer can be set at operational conditions for desired drying rate and moisture content of maize. The optimum conditions were observed at 45°C temperature of drying air with air flow rate of 400 m3h-1 for 12 hour while drying maize. [ABSTRACT FROM AUTHOR]

Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalworking industry. Low machinability and high cutting temperature generated from the contact zone are the main obstacles that need to be solved in order to improve economic and technical efficiency but still have to ensure environmental friendliness. The application of MQL method using nano cutting fluid is one of the suggested solutions to improve the cooling and lubricating performance of pure-MQL for machining difficult-to-cut materials. The main objective of this paper is to investigate the effects of nanofluid MQL (NFMQL) parameters including the fluid type, type of nanoparticles, air pressure and air flow rate on cutting forces and surface roughness in hard milling of 60Si2Mn hardened steel (50-52 HRC). Analysis of variance (ANOVA) was implemented to study the effects of investigated variables on hard machining performance. The most outstanding finding is that the main effects of the input variables and their interaction are deeply investigated to prove the better machinability and the superior cooling lubrication performance when machining under NFMQL condition. The experimental results indicate that the uses of smaller air pressure and higher air flow rate decrease the cutting forces and improve the surface quality. Al2O3 nanoparticles show the better results than MoS2 nanosheets. The applicability of soybean oil, a type of vegetable oil, is proven to be enlarged in hard milling by suspending nanoparticles, suitable for further studies in the field of sustainable manufacturing. [ABSTRACT FROM AUTHOR]

A homogeneous mixing and drying of food substance are required prior to further processing and storage. This research was carried out to determine the heat transfer parameters of an existing dryer-mixer and evaluate its performance for the drying and mixing of Irvingia gabonensis powder. A 1 kg of the powdered product (~ 15 µm particle size and 24.5% initial moisture content) was dried using the mixer-dryer for 5 hours. The average temperature of the drying chamber was preset at 50oC for the drying process, with the help of a thermostat. The heat transfer parameters, which includes the air flow rate and thickness of wall lagging, were determined mechanistically. Also, the drying performance was determined based on the drying rate, drying efficiency, mixing index, and mixing rate of the machine. Results show that an air flow rate of 0.00082 kgs-1 and 0.02 m thickness of a fibre-glass lagging material was required in the drying and mixing operation. Energy required to dry the product from 24.5% (wb) to 12.8% (wb) moisture content was 0.08514 kJ/s at a drying rate of 1.8 kgh-1. A mixing index of 0.819 and efficiency of 82.2 % were obtained, and these may imply effective drying and a high degree of homogenization in the system. [ABSTRACT FROM AUTHOR]

The air flow rate on the gas cooler side is one of the key parameters affecting the performance and running safety of transcritical CO2 electric vehicle air conditioning systems. After experimentally analyzing the effects of the air volume flow rate in the gas cooler on the cycle parameters and system performance, a novel method to evaluate the optimal air flow rate was proposed. In addition, the effect of the gas cooler air volume flow rate on the key performance parameters of the system (e.g., optimal discharge pressure) was explored. Finally, the coupling effects of the compressor speed, ambient temperature and optimal air flow rate on the system performance was also exhaustively assessed. It was found that as the discharge temperature, the CO2 temperature at the gas cooler outlet and the discharge pressure did not vary more than ±2%, the corresponding gas cooler air volume flow rate was optimal. For the single-row and dual-process microchannel evaporator used in this work, the recommended value of the optimal gas cooler air volume flow rate was 2500 m3·h−1. The results could provide reference for the fan speed design of electric vehicle CO2 air conditioning systems, especially for the performance under idling model. [ABSTRACT FROM AUTHOR]

The process of aerobic biostabilization (AB) has been adopted for treatment of the organic fraction of municipal solid waste (OFMSW). However, thermal gradients and some side effects in the bioreactors present difficulties in optimization of AB. Forced aeration is more effective than natural ventilation of waste piles, but “hot and cold spots” exist due to inhomogeneous distribution of air and heat. This study identified the occurrence of hot and cold spots during the OFMSW biostabilization process at full technical scale. It was shown that the number of hot and cold spots depended on the size of the pile and aeration rate. When the mass of stabilized waste was significantly lower and the aeration rate was two-fold higher the number of anaerobic hot spots decreased, while cold spots increased. In addition, the results indicated that pile construction with sidewalls decreased the number of hot spots. However, channelizing the airflow under similar conditions increased the number of cold spots. Knowledge of the spatial and temporal distribution of process gases can enable optimization and adoption of the OFMSW flow aeration regime. Temperature monitoring within the waste pile enables the operator to eliminate undesirable “hot spots” by modifying the aeration regime and hence improve the overall treatment efficiency.

The hybrid radiant-convective heating terminal has the advantage of combining both radiant heating and convective heating. However, the existing hybrid terminals have disadvantages of manufacturing difficulties and large thermal resistance. To solve these problems, a novel radiant-convective heating terminal was designed. And an experimental system was built to measure its heating performance. The results showed that the novel terminal had better heating performance than the existing hybrid radiant-convective heating terminals. When the terminal was in operation under radiant condition, with the increase of water temperature from 35.0 °C to 45.0 °C, the radiant, natural convective and total heating capacity rose by 26.7–54.2%, 31.0–65.1% and 28.5–58.9%, respectively. When the water flow rate rose from 0.61 kg/h to 0.73 kg/h, the total heating capacity increased from 282.6 W to 285.9 W. In addition, when the terminal was in operation under radiant-convective condition, with air flow rate ranging from 367 m3/h to 660 m3/h, the radiant and natural convective heating capacity reduced by 0.6–13.2% and 3.1–17.9% separately, and the forced convective and total heating capacity rose by 18.9–33.3% and 12.7–18.8% separately. Furthermore, with the increasing outdoor air temperature, the total heating capacity was less than that of fixed outdoor air temperature by 196.3 W. • A novel radiant-convective heating terminal was designed and processed. • The novel terminal had better heating performance than the existing hybrid radiant-convective heating terminal. • Under radiant condition, the radiant panel surface temperature rose faster with increasing water flow rate. • Under radiant-convective condition, with the elevation of air flow rate, the surface temperature of panel rose more slowly. [ABSTRACT FROM AUTHOR]

Pesticides are applied to the surface of plants by agricultural sprayers, with spray nozzles which are placed in sprayer boom to spray liquid chemicals. At that moment, blowing side wind or frequent gusts of wind can blow poisonous droplets quite far away (30 m or more). Such droplet drift poses not only environmental problems but also economic ones. Drift reduction is attempted by various technical an technological means: selecting the optimal spraying speed and spraying time, choosing different nozzle types, changing pressure of spray liquid, using additives that change properties of the spray liquid, installing spray boom vibration absorbers or various technical measures to protect the flow of sprayed droplets from the influence of wind and etc. In 2020 at the VMU Agricultural academy the Laboratory for Investigation Technological Processes of Agricultural Machinery using wind tunnel research has been carried by three different spray nozzles. It was sprayed using two air-injector nozzles A and B (spray angle -- 120°, performance -- 1.82 l min-1 at pressure -- 4 bar), and one universal (conventional) flat fan nozzle (spray angle -- 110°, performance -- 1.82 l min-1 at pressure -- 4 bar). The cross -- section of wind tunnel increases from 0.9 x 0.9 m to 1 x 1 m, respectively, and its length reaches 5 m. The stand is equipped with axial air suction fan ML 1004 DT with a ten plastic blades which diameter is 1000 mm, and electric motor (power 15 kW, rated shaft speed 1465 rpm). The Delta VFD-C2000 voltage frequency converter is used to change the speed of the motor. Changing the speed of the motor and fan impeller also changes the air flow from 2 m s-1 to 10 m s-1 (increasing proportionally every 2 m s-1). The spray liquid was supplied with a Pentair Hypro Shurflo Standard Table Spray 220 VAC. A nozzle was placed at a height of 50 cm above the surface of the liquid collection vessels. On both sides, in the longitudinal direction of the tunnel, the nozzle sprayed the liquid at 85 cm intervals, i.e. the area of the liquid droplets sprayed by the nozzle was 170 cm (when the air flow rate was 0 m s-1 ). In this case the liquid carried further than 85 cm from the nozzle is considered as drift. The nozzle was placed to investigate the effect of side direction air flow on droplet drift -- conditions were simulated when spraying in the field when the wind direction is making an angle of 90º with the direction of sprayer movement. 30 liters of liquid were sprayed during each experiment. Studies have been performed with a conventional flat fan nozzle in such a way that the drift of the liquid sprayed with it is marked (about 2 times) more than that of the air-injector spray nozzles. At the air flow rate (2 m s-1), 20.8±0.9% of the droplets were drifted by the conventional flat fan nozzle, 7.2±0.2% by the air-injector A and 10.2±0.3% by the air-injector B nozzles, respectively. After increasing the air flow velocity to 10 m s-1, the drift of droplets sprayed with a conventional flat fan nozzle reached 44.3±0.6%, with an air-injector nozzle A -- 27.2±0.6%, and with an air-injector nozzle B -- 27.9±0.2%. The increase in airflow velocity from 2 m s-1, to 10 m s-1 from conventional flat fan nozzle droplet dr ift increased more than 2-fold, and with the use of air-injector A and B nozzles, almost 3- and 4-fold, respectively. [ABSTRACT FROM AUTHOR]

The draining solar drying is considered as an innovative solution in the field of sanitation. The objective of this work is to investigate the feasibility and model the kinetics of the sludge solar drying in a lab‐scale draining greenhouse by varying the air flow rate during winter and summer. The first experiment was conducted without ventilation. Then, a series of experiences was carried out with increasing the air flow. The drying period varied between 3 and 6 days in summer and between 9 and 14 days in winter. By increasing the air velocity, the drying time decreased. For the drying rate curves, in summer, only the falling rate period existed. However, in winter, the curves did not follow any regular shape of drying kinetics. Nine mathematical equations existing in the literature were tested to identify the thin‐layer drying kinetics of sewage sludge inside the draining greenhouse. The Midilli‐Kucuk model was the most reliable for describing the evolution of reduced moisture content versus drying time in hot and cold periods. However, for different drying conditions, the Wang and Singh model was the least suitable. The results revealed also that the effective diffusivity increased when the air flow rate and the ambient temperature increased. [ABSTRACT FROM AUTHOR]

We reported a kinetic modeling of thermal reactor in Claus process using CHEMKIN-PRO software. Five hypothetical acid gases with different H2S and NH3 contents were selected and analyzed with a focus on the reaction kinetics occurring in thermal reactor. Modeling results revealed that temperature in thermal reactor initially increased due to the facile oxidation of H2S and NH3, after which it maintained a constant value due to the competing pyrolysis and S2 formation reactions. These patterns lead to equilibrium temperature and gas composition at the reactor outlet. At this point, the reactor outlet temperature and gas composition were greatly affected by the ratio of H2S/NH3 in the acid gases. Accordingly, the ratio of H2S/SO2 in the outlet gas flowing into the subsequent catalytic reactor of the Claus process was changed, necessitating an appropriate process operation. Based on these results, we suggest that the Claus process can be properly controlled by adjusting the air flow rate according to H2S/NH3 ratio. The results indicated that the ratio of H2S/SO2 in the outlet gas decreased with increasing air flow rate. It is expected that the Claus process efficiency can be improved by appropriately controlling the air flow rate in correspondence with H2S/NH3 ratio.

To reduce the adverse effects of cross winds on the performance of dry cooling towers in steam power plants, various methods such as installation of guide vanes cascades in wind direction have been used. This experimental investigation aims at evaluating the performance of guide vanes cascades under varying cross wind directions. For this purpose, effects of angle of flow at the entrance to the guide vanes cascade on the exiting flow quality and flow rate through the guide vanes cascade have been investigated using wind tunnel experiments. Results show that at zero degree angle of flow (with respect to the vane surface), the velocity distribution at the cascade outlet is uniform, the vanes' wake is small, and drop in the total pressure is about 2%. Moreover, with increase in the angle of flow at the entrance to guide vanes cascade (in the range 30° to 60°), flow uniformity diminishes and the drop in the total pressure increases, which is indicative of degradation in the performance of the guide vanes cascade. For example, at 60° angle of flow, the guide vanes cascade can only guide 20% of the total flow rate through the cascade. The results further show that for flow angles, at which cross wind strikes the back of the guide vanes cascade, installation of the cascade produces positive effects by changing the flow direction towards the cooling tower radiators, which improves the thermal performance of the radiators.

In this paper, heating and humidification of air for space have been carried out by using a phase change material (PCM)-based solar-powered desiccant wheel air conditioning (SPDWAC) in winter. The analysis of the setup has been done at different air flow rates. At low and high air flow rates, system has mean thermal coefficient of performance of 0.121 and 0.172, respectively, and mean exergy efficiency of 0.0787 and 0.0846, respectively. The mean thermal coefficient of performance of the system at high air flow rate (127.23 kg h-1) is 1.42 times the low air flow rate (63.62 kg h-1) and average exergy efficiency of the system at high air flow rate is 1.07 times the low air flow rate. It is observed that with an increase in air flow rate, efficiency of the evacuated tube solar air collector (ETSAC) increases. The average efficiency of the ETSAC at high air flow rate is 15.60%. The maximum average energy efficiency (17.80%) and exergy efficiency (17.08%) of the PCM storage system have been obtained at high air flow rate. The overall performance of the system showed that the use of PCM storage is feasible to run the system in winter during the hours of darkness.

In order to investigate the effect of air flow rate distribution on plate flow field characteristics, an experiment of plate with air injection was conducted in a high speed towing tank. The influence of air flow rate distribution at longitudinal and transverse on drag reduction and the morphology of air layer were investigated. The result show that the air-water mixed flow under the plate surface is mainly affected by the velocity of flow and air flow rate. When the non-dimensionalzed air flow rate coefficient is less than 1.554 (Cq≤1.554), the mixed flow mainly has a bubbly flow; when the non-dimensionalized air flow rate coefficient is greater than 2.331 (Cq≥2.331), the mixed flow has an air-water stratified flow; Otherwise, there is a transitional flow that is both bubbly and stratified. The local friction drag reduction at the lower surface of the plate near the injection is 100%. The drag reduction rate of total resistance for the lower surface of flat plate will reach 60.65% when improves the strategies of air injection and the air ratio is 1:4:1 in the header air injection device. The joint air injection of header and central device has no contribution to the drag reduction rate of total resistance.

The gas temperature of the supersonic heat airflow simulated test system is mainly determined by the fuel and air flow rates which enter the system combustor. In order to realise a high-quality control of gas temperature, in addition to maintaining the optimum ratio of fuel and air flow rates, the dynamic characteristics of them in the combustion process are also required to be synchronised. Aiming at the coordinated control problem of fuel and air flow rates, the mathematical models of fuel and air supply subsystems are established, and the characteristics of the systems are analysed. According to the characteristics of the systems and the requirements of coordinated control, a fuzzy-PI cross-coupling coordinated control strategy based on neural sliding mode predictive control is proposed. On this basis, the proposed control algorithm is simulated and experimentally studied. The results show that the proposed control algorithm has good control performance. It cannot only realise the accurate control of fuel flow rate and air flow rate, but also realise the coordinated control of the two. [ABSTRACT FROM AUTHOR]