Air Distributors Research Articles

Increasing Economic Efficiency When Creating a Dynamic Microclimate in Compressed Conditions of Production Premises

This work is devoted to increasing economic efficiency when using two-stream air distributors that form a swirled and flat stream while providing a dynamic microclimate in compressed conditions of industrial premises. The design of a two-jet air distributor is proposed, which forms a swirled and flat laying air jet, that provides intensive attenuation of air flow velocity and temperature in stationary and variable mode. Measures aimed at saving cold energy are considered, namely, air supply in a variable mode, use of the flooring effect, use of devices for intensification of tidal flow turbulence. A set of optimal measures for obtaining the maximum economic effect is determined. A method of development and calculation of inflow mechanical ventilation systems based on the specified air distributors is proposed. The economic evaluation of the use of air distribution devices proved that the use of a two-jet air distributor makes it possible to obtain some economic effect.

Study of bubble behavior in a gas–solid dense-phase fluidized bed based on deep learning

Fluidization characteristics and hydrodynamics of gas–solid fluidized beds are controlled by bubble properties. However, the existing conventional image segmentation methods are unable to effectively resolve the problems of overlap and background interference between small bubbles, and the segmentation performance for bubbles must still be enhanced. To study the bubble behavior of a gas–solid dense-phase fluidized bed, a two-dimensional fluidized bed with different air distributors was adopted. The application of deep learning to digital image analysis technology is to improve the precision and automation of bubble recognition. The DeepLab V3+ model incorporates multi-scale information, which is well-compatible with uncertain bubble boundary information while enhancing the segmentation effect. A pixel accuracy of 97.95% and a mean intersection over union (MIoU) of 80.91% for multi-group bubble image segmentation were achieved. In comparison to conventional threshold-based recognition methods, the accuracy of the deep learning method increased by up to 40.31% and the MIoU by up to 53.88%, demonstrating the great potential and application value of semantic segmentation in the study of the complex motion behavior of gas–solid sorting fluidized bed bubbles. The influence of the air distributor on the behavior of bubbles is verified. The results indicate that air distributor aperture directly influences bubble diameter, aspect ratio, and shape factor, with coalescence being the primary cause of bubble enlargement.

Numerical Optimization Study of the Resistance Coefficient of U-Shaped Air Distributor

In this paper, the optimization of the flow channel structure of the U-shaped air distributor is proposed. Fluent meshing was used to mesh the multipatch meshing of the original model of the grid air distributor, and then the CFD numerical simulation was carried out by using Fluent 2022R1 to obtain the internal air flow state of the air distributor flow channel. Through the orthogonal experimental design and a comprehensive analysis method, the optimal size structure for resistance performance is obtained as S = 60 mm, RL = 125 mm, L = 160 mm, D = 100 mm, the resistance coefficient of the new structure as 1.375, and the pressure loss as 56.87 Pa, by using 3D modeling software (SOLIDWORKS 2015) and Fluent. Compared with the initial scheme, the resistance coefficient and pressure loss are reduced by 3.03% and 6.29%, respectively. To summarize, the research in this paper offers a substantial contribution to the realm of energy conservation and emission abatement in ship air conditioning systems, simultaneously furnishing invaluable guidance for the design of air distributors.

Гравитационная транспортная система: принципы построения и управления

The paper considers the principle of constructing a gravitational transport system designed for container transportation of the technological materials. It proposes a scheme of the transport system providing the container shuttle motion between the stations. A scheme is developed, and description of the stations operation principle is presented being a part of the transport system; the compressed air energy is used there to provide transport container with the potential energy ensuring its motion along the transport route under the gravity influence. The proposed station scheme makes it possible to consider the station as a functionally complete module forming the basis for possible development of the extended transport systems with various configurations. An algorithm for the station functioning was developed that implemented the processes of sending and receiving a container. A microprocessor system for managing the station mechanisms is proposed, which controls the sensor signals state and generates control signals for the compressed air distributors. A computer model of the control system was designed and developed to debug algorithms for controlling the transport system stations. The considered schemes and algorithm are intended to develop the technological transport lines.

Performance evaluation of bubble column humidifier using various air distributors in a humidification-dehumidification desalination plant

A humidification-dehumidification (HDH) system using a bubble column humidifier was optimized using response surface methodology (RSM). The humidifier was integrated with four types of air distributors entitled the horizontal cuts (H-cuts) and vertical cuts (V-cuts) spargers with the same total hole area, as well as the multiple orifice nozzles (M-orifice) and perforated plate with equal hole diameters. The experimental investigation consisted of a parametric study, optimization using RSM, and bubble characteristics using image analysis. The effects of a qualitative parameter (i.e., the type of air distributors) and quantitative parameters (i.e., the inlet water temperature, superficial air velocity into the humidifier as well as the water height inside the humidifier) on the absolute humidity of the air leaving the humidifier were studied. The H-cuts and M-orifice spargers were found as the best air distributors in their subclasses due to higher gas holdup, specific interfacial area, and lower Sauter mean diameter. The humidifier performance was optimized in the lowest superficial air velocity (0.195 m/s), the highest water height inside the humidifier (50 cm) and the inlet water temperature to the humidifier (90 °C). It was concluded that the H-cuts and M-orifice spargers at the optimum values of the quantitative parameters achieved the maximum absolute humidity of about 0.18 and 0.143 kg water vapor/kg dry air, respectively.

Digital Twin of HVAC system (HVACDT) for multiobjective optimization of energy consumption and thermal comfort based on BIM framework with ANN-MOGA

ABSTRACT This study proposes a novel Digital Twin framework of heating, ventilation, and air conditioning (HVACDT) system to reduce energy consumption while increasing thermal comfort. The framework is developed to help the facility managers better understand the building operation to enhance the HVAC system function. The Digital Twin framework is based on Building Information Modelling (BIM) combined with a newly created plug-in to receive real-time sensor data as well as thermal comfort and optimization process through Matlab programming. In order to determine if the suggested framework is practical, data were collected from a Norwegian office building between August 2019 and October 2021 and used to test the framework. An artificial neural network (ANN) in a Simulink model and a multiobjective genetic algorithm (MOGA) are then used to improve the HVAC system. The HVAC system is comprised of air distributors, cooling units, heating units, pressure regulators, valves, air gates, and fans, among other components. In this context, several characteristics, such as temperatures, pressure, airflow, cooling and heating operation control, and other factors are considered as decision variables. In order to determine objective functions, the predicted percentage of dissatisfied (PPD) and the HVAC energy usage are both calculated. As a result, ANN's decision variables and objective function correlated well. Furthermore, MOGA presents different design factors that can be used to obtain the best possible solution in terms of thermal comfort and energy usage. The results show that the average cooling energy savings for four days in summer is roughly 13.2%, and 10.8% for the three summer months (June, July, and August), keeping the PPD under 10%. Finally, compared to traditional approaches, the HVACDT framework displays a higher level of automation in terms of data management.

3D Computational Fluid Dynamics Analysis of a Convective Drying Chamber

The drying industry has grown considerably due to the tremendous demand for non-perishable food. Convective drying is one of the most popular equipment in the drying industry (food, chemical, pharmaceutical, etc.). One of the drawbacks of this equipment, when used for convective drying, is the non-uniformity in the final product quality. This study presents the development of a numerical model through Computational Fluid Dynamics (CFD). The drying chamber of a heat pump dryer is assessed from the perspective of drying air velocity and temperature profiles. The model was developed by solving different transport phenomena-related equations. The established methodology was set up to evaluate how the drying air velocity and temperature distribution affect the drying chamber. These results will define if there is a need to redesign it. The air velocity and temperature profile results show a need to redesign the chamber. Only trays 2, 3, and 4 are the ones that would achieve the drying of the products. The proposed solution is to implement air distributors or modify the tray positioning to make the drying air and temperature distribution homogeneous.

Effect of conical air distributors on drying of peppercorns in a fluidized bed dryer: Prediction using an artificial neural network

The effect of conical air distributors on the drying of peppercorns in a fluidized bed dryer was experimentally studied. A flat perforated sheet was installed in the column at the base of the bed. Conical air distributors consisted of two parts. The first was a solid cone located below an air duct, while the second part was a perforated metal cone placed on the flat perforated sheet. Experiments were carried out using perforated metal cones with three different height to base diameter ratios, ( h/H ) values of 0.5, 1.0, and 1.5 and three different air velocities, 1.2 U mf , 1.6 U mf , and 2.0 U mf . An air distributor, consisting of a solid cone and a perforated metal cone with h/H = 1.0 and an air velocity of 2.0 U mf , showed the best drying performance. It was also discovered that increasing the air velocity accelerated the drying process. A neural network was created to predict the moisture content of peppercorns during the drying process. The split, sample type, spilt ratio, momentum, and learning rate, as well as the numbers of hidden layers, hidden nodes, and training cycles all had an impact. A maximum coefficient of determination of 0.996 was found for the best model.

Drying Performance of Piper Nigrum in a Swirling Fluidized Bed Dryer: An Experimental Study

Sun drying is widely used in drying agricultural products such as piper nigrum because of its ability to dry a high volume in one batch. However, this conventional method of drying has many disadvantages, especially on the hygienic issue. This study investigates the drying performance of piper nigrum by using conventional sun drying and a new dryer called Swirling Fluidized Bed Dryer. Swirling fluidized bed dryer is operated using two inclination angles of air distributors, namely 45°, 67° and one perforated plate distributor. The drying performance is accessed in terms of drying time and moisture content reduction at three different operating temperatures. The results show that the drying time of piper nigrum using a swirling fluidized bed dryer is reduced as compared to conventional sun drying. Besides, the drying performance between different distributors in swirling fluidized bed shows that the moisture content reduction of piper nigrum using 45° angle of air distributor shows the most reduction compared to 67° angle distributor and followed by the perforated distributor. In conclusion, results show that the drying of piper nigrum in a swirling fluidized bed operated with 45° inclination angle of the distributor at high operating temperature gives the best performance.

Computational Analysis of the Hydrodynamic Behavior for Different Air Distributor Designs of Fluidized Bed Gasifier

Fluidized bed gasification has proven to be an appropriate technique for converting various biomass feedstocks into helpful energy. Air distributor plate design is one of the critical factors affecting the thermochemical conversion performance of fluidized bed gasifiers. The present study is proposed to investigate the mixing pattern and pressure drop across different configurations of air distributors using a two-fluid model (TFM) of finite volume method-based solver ANSYS FLUENT. The pressure drop across the bed and mixing pattern have been investigated through qualitative and quantitative analysis of CFD results using three diverse distributor plate designs: perforated plate, 90° slotted plate, and 45° swirling slotted plate. The pressure drop by employing the perforated distributor plate reveals the highest pressure drop due to the smallest open area ratio. However, the pressure drop in the case of 90° slotted plate is found to be 7% and 4% lesser than perforated and 45° slotted plate respectively due to a smaller velocity head developed through the wider open area of the straight slotted plates. The distributor design configuration having a 45° slotted plate exhibits considerable pressure drop compared to the 90° slotted plate due to the longer path length of the slot. Numerical pressure drop results across the bed with different types of distributor plates prove reasonable agreement with the experimental results available in the literature. Mixing behavior in perforated distributor plates exhibits lower portion solid volume fraction of around 0.58. However, it falls rapidly as go up the riser (7.7% of column height); 90° slotted plate shows bottom region solid volume fraction of around 0.5. In addition, it exhibits an even broader range of sand volume fraction and column height (13.46% of column height). Finally, the 45° distributor plate reveals the highest range of volume fraction through the riser height (17.3% of column height), indicating the better mixing characteristics of the fluidized zone.

Assessment of Mini-Tablets Coating Uniformity as a Function of Fluid Bed Coater Inlet Conditions.

This study concerned the quality of mini-tablets’ coating uniformity obtained by either the bottom spray chamber with a classical Wurster distributor (CW) or a swirl distributor (SW). Mini-tablets with a diameter of 2.0, 2.5, and 3.0 mm were coated with hypromellose using two different inlet air distributors as well as inlet airflow rates (130 and 156 m3/h). Tartrazine was used as a colorant in the coating layer and the coating uniformity was assessed by spectrophotometric analysis of solutions obtained after disintegration of the mini-tablets (n = 100). Higher uniformity of coating material distribution among the mini-tablets was observed in the case of SW distributor, even for the biggest mini-tablets (d = 3.0 mm), with an RSD no larger than 5.0%. Additionally, coating thickness was evaluated by colorimetric analysis (n = 1000), using a scanner method, and expressed as a hue value. A high correlation (R = 0.993) between inter-tablet variability of hue and UV-Vis results was obtained. Mini-tablets were successfully coated in a fluid bed system using both a classical Wurster distributor as well as a swirl generator. However, regardless of the mini-tablets’ diameter, better film uniformity was achieved in the case of a distributor with a swirl generator.

Air temperature stratification when flowing between rooms

The article presents the regularities of the vertical change in the air temperature of a ventilated room for various purposes, where the excess of sensible heat dominates, in the first case, when there is no process of air flow through the opening in a common vertical fence between the rooms located in a row, or the second case, when a similar air flow is observed. In heat-stressed rooms, the general ventilation arrangement scheme provides for the removal of air from the upper volume of the room. To determine the required air exchange with point, two-zone or multi-zone mathematical models of a ventilated room, it is necessary to have a reliable apparatus for determining the gradient of the vertical air parameters change for a ventilated room. The reasonably determined value of the gradient of the air temperature change along the vertical of the ventilated room makes it possible to calculate the air flow between different volumes inside the ventilated room. Determination of the air temperature near the suction flare makes it possible to determine the required air exchange more reasonably. A method is given for calculating the distribution of air temperature in rooms with an excess of apparent heat over the height of the room in the first case, when there is no process of air flow through the opening in the common vertical fence between the rooms located in a row, or the second case, when a similar air flow is observed. This takes into account the height of the supply air distributors relative to the working (serviced) area. Reasonable determination of the air temperature at different points in the room with an excess of sensible heat allows a correct calculation of the required air exchange. The presented method for determining the gradient of air temperature stratification along the height of the room with air flow between adjacent rooms and without it contributes to the reasonable determination of the air temperature at the suction flame of the exhaust air distributor, which increases the reliability of calculating the required air exchange.

To the problem of train running safety

The paper is presenting the procedure used for establishing the cause of the wagon derailment. To do this, the computer simulations and the computational software, developed in the Dnipro National University of Railway Transport (DIIT) were used. The level of longitudinal forces and the wagons dynamic performance have been evaluated using the mathematical models of longitudinal oscillations of a train and the spatial vibrations of wagons, in particular of tank wagons. As a result of modeling we obtained oscillograms of longitudinal forces in each inter-wagon connection, the dependence of the largest longitudinal forces on travel time and distance traveled, the distribution of the maximum longitudinal forces along the train length, the speed dependence on travel time and track coordinates. We also obtained the dynamic performance of wagons: the vertical dynamics coefficients of the axle-box and central suspension, the horizontal dynamics coefficients and the derailment stability coefficient. The influence of the movable load in the tank wagons and the characteristics of rail irregularities on the stability coefficient against wheel climbing onto the rail is also considered. The presented methodology was used to determine the cause of the tank wagon derailment in a non-homogenous freight train consisting of 50 wagon tanks on an existing track section of the Lithuanian railways. When simulating the train movement, it was assumed that the train was equipped with elastic-friction absorbing devices and air distributors, turned on to the average operation mode. As a result of numerical experiments, an assumption was made about the cause of the train derailment.

Modern Air-Conditioning Systems without Wiring Duct

The calculation involved in the design of integrated heat-hydraulic air-conditioning system in which air is supplied through the raised floor was presented. Calculations were made using the premises of an office building in Yekaterinburg, Russia. Raised floor in the current study was presented in the form of a channel with a concrete wall on one side and chipboard -on the other. It has been successfully established that the loss of pressure during air movement in the raised floor space is minimal, this was suggested as a result of the possible uniformity in air supply to the air distributors. It was also demonstrated that due to transmission losses through the walls of the raised floor, the cooling capacity of the air conditioning system was significantly reduced (up to 15%). Following the results obtained, conclusions were drawn about the main features of such systems.

Determination of Heat Transfer Coefficients in Air-Solid Fluidized Bed

The heat transfer of gas-solid fluidized bed has been investigated using pre-heating system. A Perspex column of 7cm inner diameter and 1.5 m height is used as a fluidizing column filling with three different sizes of sand with a height of 21 cm as packing.The experimental work is carried out under superficial air velocities ranged of (0.029-0.365) m/s. The effect of opening area air distributors, particle diameter of sand packing, and different heat fluxes as powers have been investigated. The results show that the minimum fluidizing velocity increases with increasing the particle diameter and opening area of distributor. The gas-particle heat transfer coefficient is found to be increased by increasing superficial velocity, heat flux and opening area of distributor and decreased by particle diameter.A mathematical correlation of dimensionless groups based on experimental data has been suggested. A comparison between results of present correlation and the speculations of previous ones has been made.

STUDY PERFORMANCE INDICATORS OF CAR REPAIR COMPLEX AND TRAFFIC SAFETY

The article analyzes structure of cases lack cars, which includes technical aspects and factors labor discipline, attitude managers and executors to issues traffic safety. It has been established that 58% cases marriage are technological nature, 40% are due human factor and only 2% are due to technical reasons. The block diagram of systematization and structuring factors influencing conditions trouble-free work car-repair complex research range is developed and constructed. The main factors are part model safe operation of rolling stock are formulated. Model distribution basic lacks functioning car economy is constructed. Aspects application are determined. A model for monitoring degree professionalism of railway specialists as tool improve traffic safety in railway transport has been developed. The space indicators of intellectual and technological safety functioning car economy branch is defined. To increase length warranty areas, it is planned to create maintenance point system of network value, which has latest maintenance technology. The main types of marriage are: malfunction body and frame car; violation integrity brake line; malfunctions air distributors; adjustment brake lever transmission; malfunction automatic regulators car modes; auto-coupling breakage and cases self-disengagement; axle box failure. Checking consistency theoretical distribution of empirical frequencies is necessary establish adequacy mathematical model to real object study, namely failure rolling stock, which contributes occurrence cases of traffic safety violations. To select and substantiate theoretical laws distribution, the most common faults rolling stock on railway were investigated and statistical models distribution random variables over time were built. According block diagram of systematization and structuring factors influencing conditions accident-free operation car repair complex research site, main factors are 6. Each these factors is broken down into factors more specific content, and they are broken down into more detailed factors. Each factors is characterized by one or another aspect application depending on root cause and nature of occurrence (technical, technological, organizational).

Air Distributor Pressure Drop Analysis in a Circulating Fluidized‐Bed Boiler for Non‐reference Operating Conditions

AbstractThe air distributor plays a key role in circulating fluidized‐bed (CFB) boilers providing an even gas distribution in the cross section of the furnace. In most cases, this task under real conditions is very difficult to implement due to the destruction of the tuyeres. For this reason, the air distributors of many CFB boilers operate under conditions deviating from the design recommendations, which has a direct impact on the hydrodynamics of the fluidized bed and heat transfer conditions. This work reports studies on the performance of a tuyere‐type air distributor utilized in a CFB boiler and working under non‐reference operating conditions. Based on the results of simulation calculations, practical equations for a distributor pressure drop calculation have been derived taking into account a different degree of tuyere destruction.

Reduction of temperature influence in temperature-controlled rooms in the engineering industries

Typical air conditioning and ventilation systems are used to create and maintain microclimate parameters. Analytical studies have shown that the existing ventilation systems do not provide proper maintenance of the required parameters of the environment, since the influence of the temperature of the enclosing structures is not taken into account. Thus, the paper proposes the structure of the air conditioning System (ventilation), which provides a sufficiently high degree of air purity and excludes temperature increase on the enclosing structures of the thermoconstant room. The technical result is achieved due to the fact that the air conditioning system additionally contains air distributors for supplying air that adheres to the enclosing structures along the perimeter of the clean zone, and devices for removing this air, connected to exhaust air ducts located along the perimeter of the zone at certain intervals. The application of numerical simulation of air parameters in a thermoconstant room was also analyzed using cleanroom software that allows evaluating the degree of temperature impact from enclosing structures.

Optimisation of air-distributor channel structural parameters based on Taguchi orthogonal design

Air distributors are a typical kind of ventilation terminal that are widely used in air-conditioning systems. However, the high flow resistance of traditional air distributors leads to huge energy losses and poor indoor thermal comfort. Therefore, this paper uses experimental and numerical methods to examine the influence of key structural parameters on the resistance coefficient of air distributors. First, a resistance-coefficient test is carried out, and based on the test results a computational fluid dynamics model is developed. Second, a Taguchi design table is created and numerical simulation data are collected. Finally, the prediction results of Mean Response and Assisted Regression are compared. The resistance coefficient of prediction combination of Assisted Regression model is lower, so the optimal scheme is as follows: d = 90 mm, D = 155.5 mm, and h = 96.5 mm. The predicted resistance coefficient is 1.503, and the difference between the predicted and simulation results accords with the 95% confidence interval. These findings show that numerical simulation and the analysis method based on the orthogonal design presented in this paper enable the optimal design of an air distributor.

Features of Functioning of the Combined Air Heating Systems and Ventilation of a Three-story Museum

The analysis of the air-thermal regime of a three-story experimental residential museum building with a basement floor is presented. The equations of material and energy balances of the investigated building were compiled, allowing to determine the required air temperature at the outlet of the stream from the air-heating chamber. A method for determining the maximum performance of an air heater of a combined air heating and ventilation system at given temperatures of outside air and fresh air at the outlet of the jet from the air distributor is presented. The dependence of the thermal performance of the air heater on the change in the outside air temperature is established, with the same parameters of supply air at the outlet of the air distributors. A method for determining the parameters of supply air at the outlet of the jet from the air distributor, which allows to ensure the necessary parameters of the air inside the heated premises, is proposed. A survey of the temperature and humidity of the microclimate in the premises of the building, allows us to estimate the sanitary and hygienic conditions. A method for the simultaneous application of the processes of humidification and heating of the supply air in the combined air heating and ventilation system providing the specified microclimate parameters in the premises of the building under study is proposed.