scholarly journals Experimental Study on the Influence of an Extension Tube on the Evolution Process and Characteristic Parameters of a Gliding Arc

2019 ◽  
Vol 9 (7) ◽  
pp. 1347
Author(s):  
Shida Xu ◽  
Feilong Song ◽  
Xingkui Yang ◽  
Yepan Zhong ◽  
Yun Gao
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Rotation Frequency ◽  
Tensile Fracture ◽  
Arc Length ◽  
Air Flow Rate ◽  
Characteristic Parameters ◽  
Regeneration Frequency ◽  
Gliding Arc ◽  
Extension Tube

The influence of the discharge cone size on the characteristic parameters of a rotating gliding arc, e.g., arc length, arc rotation frequency, and regeneration frequency was investigated when the grounding electrode was equipped with an extension tube. In addition, the effect of air flow rate (100~400 standard liter per minute, SLPM) on the characteristic parameters was also studied (with an extension tube, using a No. 5 discharge cone). The results showed that the disturbance of the outlet flow was intense without an extension tube, which led to the occurrence of the short-circuit regeneration of the gliding arc when the discharge gap was small, and the short-circuit regeneration of the gliding arc could be effectively avoided by adding an extension tube at the grounding end. The existence of the extension tube could significantly increase the arc length by up to 140 mm (250 SLPM, No. 3 discharge cone). The arc lengthening was mainly caused by the unilateral extension of the high voltage side, and the arc shape changed from a “C” to an “L” shape. This also reduced the regeneration frequency to one-quarter of the arc regeneration frequency without extending the tube. Without lengthening the tube, the arc could not achieve complete circumferential rotation. The arc distribution in the annular area between the anode and the cathode was discrete, and the arc distribution was extremely uneven. The existence of the extension tube made the arc rotate uniformly, and the maximum rotation frequency was 228 Hz. The influence of the air flow rate on arc length was mainly reflected in the small flow rate range. When the air flow rate was less than 200 SLPM, the arc length increased first, and then decreased with the increase of the air flow rate, reaching the maximum arc length of 143.6 mm at 150 SLPM. The arc frequency was positively correlated with the air flow rate, but the rotation frequency increased faster than the regeneration frequency: when the flow rate was 150 SLPM, the gliding arc rotated one circle in a tensile fracture period; when the flow rate reached 400 SLPM, the gliding arc rotated two circles in a tensile fracture period.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Modeling and optimization of radish root extract drying as peroxidase source using spouted bed dryer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shahrbanoo Hamedi ◽  
M. Mehdi Afsahi ◽  
Ali Riahi-Madvar ◽  
Ali Mohebbi
Keyword(s):  
Kinetic Parameters ◽  
Flow Rate ◽  
Air Flow ◽  
Cost Effective ◽  
Industrial Applications ◽  
Interactive Effects ◽  
Root Extract ◽  
Air Flow Rate ◽  
Spouted Bed ◽  
Radish Root

AbstractThe main advantages of the dried enzymes are the lower cost of storage and longer time of preservation for industrial applications. In this study, the spouted bed dryer was utilized for drying the garden radish (Raphanus sativus L.) root extract as a cost-effective source of the peroxidase enzyme. The response surface methodology (RSM) was used to evaluate the individual and interactive effects of main parameters (the inlet air temperature (T) and the ratio of air flow rate to the minimum spouting air flow rate (Q)) on the residual enzyme activity (REA). The maximum REA of 38.7% was obtained at T = 50 °C and Q = 1.4. To investigate the drying effect on the catalytic activity, the optimum reaction conditions (pH and temperature), as well as kinetic parameters, were investigated for the fresh and dried enzyme extracts (FEE and DEE). The obtained results showed that the optimum pH of DEE was decreased by 12.3% compared to FEE, while the optimum temperature of DEE compared to FEE increased by a factor of 85.7%. Moreover, kinetic parameters, thermal-stability, and shelf life of the enzyme were considerably improved after drying by the spouted bed. Overall, the results confirmed that a spouted bed reactor can be used as a promising method for drying heat-sensitive materials such as peroxidase enzyme.

Method to Determine an Optimal Air-Flow Rate in Solar Collectors

1979 ◽  
Vol 3 (6) ◽  
pp. 357-362
Author(s):  
H. C. Hewitt ◽  
E. I. Griggs
Keyword(s):  
Flow Rate ◽  
Air Flow ◽  
Solar Collectors ◽  
Air Flow Rate

Model-Based Analysis of Transient Behavior of Large Scale CFB Boilers

2003 ◽  
Author(s):  
Ari Kettunen ◽  
Timo Hyppa¨nen ◽  
Ari-Pekka Kirkinen ◽  
Esa Maikkola
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Air Flow ◽  
Model Parameters ◽  
Air Flow Rate ◽  
Process Data ◽  
Cfb Boiler ◽  
Flow Rates ◽  
Load Change ◽  
Secondary Air

The main objective of this study was to investigate the load change capability and effect of the individual control variables, such as fuel, primary air and secondary air flow rates, on the dynamics of large-scale CFB boilers. The dynamics of the CFB process were examined by dynamic process tests and by simulation studies. A multi-faceted set of transient process tests were performed at a commercial 235 MWe CFB unit. Fuel reactivity and interaction between gas flow rates, solid concentration profiles and heat transfer were studied by step changes of the following controllable variables: fuel feed rate, primary air flow rate, secondary air flow rate and primary to secondary air flow ratio. Load change performance was tested using two different types of tests: open and closed loop load changes. A tailored dynamic simulator for the CFB boiler was built and fine-tuned by determining the model parameters and by validating the models of each process component against measured process data of the transient test program. The know-how about the boiler dynamics obtained from the model analysis and the developed CFB simulator were utilized in designing the control systems of three new 262 MWe CFB units, which are now under construction. Further, the simulator was applied for the control system development and transient analysis of the supercritical OTU CFB boiler.

scholarly journals Experimental Investigation on Improvement of Wet Cooling Tower Efficiency with Diverse Packing Compaction Using ANN-PSO Algorithm

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 167
Author(s):  
Hasan Alimoradi ◽  
Madjid Soltani ◽  
Pooriya Shahali ◽  
Farshad Moradi Kashkooli ◽  
Razieh Larizadeh ◽  
...  
Keyword(s):  
Neural Network ◽  
Water Temperature ◽  
Water Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Air Flow ◽  
Water Flow Rate ◽  
Pso Algorithm ◽  
Outlet Temperature ◽  
Air Flow Rate

In this study, a numerical and empirical scheme for increasing cooling tower performance is developed by combining the particle swarm optimization (PSO) algorithm with a neural network and considering the packing’s compaction as an effective factor for higher accuracies. An experimental setup is used to analyze the effects of packing compaction on the performance. The neural network is optimized by the PSO algorithm in order to predict the precise temperature difference, efficiency, and outlet temperature, which are functions of air flow rate, water flow rate, inlet water temperature, inlet air temperature, inlet air relative humidity, and packing compaction. The effects of water flow rate, air flow rate, inlet water temperature, and packing compaction on the performance are examined. A new empirical model for the cooling tower performance and efficiency is also developed. Finally, the optimized performance conditions of the cooling tower are obtained by the presented correlations. The results reveal that cooling tower efficiency is increased by increasing the air flow rate, water flow rate, and packing compaction.

Parametric study on pressure-based packed bed adsorption system for air dehumidification

2021 ◽  
pp. 095440892110073
Author(s):  
V Sureshkannan ◽  
TV Arjunan ◽  
D Seenivasan ◽  
SP Anbuudayasankar ◽  
M Arulraj
Keyword(s):  
Genetic Algorithm ◽  
Taguchi Method ◽  
Flow Rate ◽  
Uptake Rate ◽  
Air Flow ◽  
Packed Bed ◽  
Air Pressure ◽  
Dew Point ◽  
Adsorption System ◽  
Air Flow Rate

Compressed air free from traces of water vapour is vital in many applications in an industrial sector. This study focuses on parametric optimization of a pressure-based packed bed adsorption system for air dehumidification through the Taguchi method and Genetic Algorithm. The effect of operational parameters, namely absolute feed air pressure, feed air linear velocity, and purge air flow rate percent on adsorption uptake rate of molecular sieve 13X-water pair, are studied based on L25 orthogonal array. From the analysis of variance, it has been found that absolute feed air pressure and purge air flow rate percent were the parameters making significant improvement in the adsorption uptake rate. A correlation representing the process was developed using regression analysis. The optimum adsorption conditions were obtained through the Taguchi method and genetic algorithm and verified through the confirmation experiments. This system can be recommended for the industrial and domestic applications that require product air with the dew point temperature below 0°C.

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