scholarly journals The effect of trays’ slope in the tunnel dryer on drying rate of carrot cubes

2018 ◽  
Vol 4 (21) ◽  
pp. 345-356
Author(s):  
Jarosław Kubiaszczyk ◽  
Ewa Golisz ◽  
Małgorzata Jaros
Keyword(s):  
Air Flow ◽  
Slope Angle ◽  
Food Preservation ◽  
Comsol Multiphysics ◽  
Drying Rate ◽  
Tunnel Dryer ◽  
Heated Air ◽  
Air Stream ◽  
Flow Through ◽  
Air Flow Velocity

Drying of food is perhaps the oldest method of food preservation. The aim of this study the analysis of the effect of changing the slope angle of trays in a tunnel dryer model on the drying rate. Real experiments were carried out for trays’ slopes of 0, 5, 10 and 15°. Carrots’ cubes were dried at a constant temperature of 60°C, with air flow velocity of 1.2 m/s. Also this process was simulated using the COMSOL Multiphysics 4.3 software. The research results showed that increasing slope angle of tray disrupted the laminar flow of the dried cubes layer through the drying air stream and forced the partial air flow through the layer. Thus, the contact surface of the heated air with the material particles and the drying rate have been increased and made it possible to shorten the duration of the drying.

scholarly journals Experimental Study on the Atomization of Plain Orifice Injector Under Uniform and Non-Uniform Cross Flowing Air Stream

1987 ◽  
Author(s):  
Yan Zhang ◽  
Jun Yong Zhu ◽  
Li Xin Wang ◽  
Ju Shan Chin
Keyword(s):  
Pressure Drop ◽  
Flow Velocity ◽  
Air Flow ◽  
Cross Flow ◽  
Orifice Diameter ◽  
Air Velocity ◽  
Air Stream ◽  
Nozzle Pressure ◽  
Large Orifice ◽  
Air Flow Velocity

The effects of three parameters: air velocity, nozzle pressure drop and injector orifice diameter, on the spray characteristics of a plain orifice injector under uniform and non-uniform cross flowing air stream have been studied experimentally. For uniform cross flowing air stream, the results show that the effects of these parameters are interrelated. The exponents of these terms in a correlation are not constants. Based on a very large amount of experimental data, the following correlation has been derived for Sauter Mean Diameter. SMD = 8.28 • 10 4 V ¯ a A • Δ P ¯ f B • d ¯ C where: A = −1.59 −0.0044ΔP̄f −0.01 d̄ B = −0.13 −0.025 d̄ +0.34 Ma C = 0.36 −0.55 Ma −0.0032ΔP̄f (Va ≤ 140 M/s ; ΔPf ≤ 11 Kg·f/cm2 ; d ≤ 2.5 mm) For small orifice diameters, the drop size distribution parameter, N (Rosin-Rammler distribution ), decreases until a minimum then increases with air velocity. For large orifice diameters, it decreases with air velocity. N always decreases with the increases of nozzle pressure drop or orifice diameter. For non-uniform cross flowing air stream, atomizations under four velocity profiles with same averaged velocity and with a velocity recess of same shape but at different radial positions have been tested. The atomization data were compared with that of uniform cross flowing air stream. Two types of comparison were made based on: a) the undisturbed velocity, b) the averaged velocity, equals to the velocity of uniform cross flowing air stream. For former situation the atomization for non-uniform cross flowing air stream tested is always poorer. The influence from the velocity recess will be maximum at certain nozzle pressure drop. The experimental evidence obtained has shown that cross flow atomization is a combination of pressure atomization (at low air flow velocity) and airblast atomization (at high air flow velocity).

scholarly journals Properties of Fuel Spray Obtained by Electrohydrodynamic Atomization

2017 ◽  
Author(s):  
Michel Daaboul ◽  
Nicolas Saba ◽  
Jihad Rishmany ◽  
Christophe Louste
Keyword(s):  
High Speed ◽  
Air Flow ◽  
Mesh Size ◽  
Liquid Sheet ◽  
High Speed Camera ◽  
Aircraft Engines ◽  
Shear Forces ◽  
Dielectric Barrier ◽  
Air Stream ◽  
Air Flow Velocity

Airblast atomization is com monly used to atomize fuel in aircraft engines. An annular liquid sheet is atomized bythe shear forces exerted by the co-flowing air stream. Nevertheless, this technique is less effe ctive in some specific cases, e.g. when the external air flow velocity is relatively low. Electrohydrodynamic (EHD) atomization can constitute a solution in these cases. It consists of applying an electric field between two electrodes and electricallycharging the passing carburant. This phenomenon will create instabilities within the liquid, provoking therefore its atomization. The main objective is therefore to electrically atomize a liquid sheet without the application of an external air flow like in airblast atomizers.This paper presents a novel actuator, based on dielectric barrier injection, used to induce instabilities within a plane liquid sheet of fuel similar to the annular sheet in aircraft engines. The behaviour of this atomizer was described in previous works. Several modes were observed, sometimes leading to a complete atomization, or just inducing instabilities and oscillating the liquid sheet. In the present study, only the cases where the liquid sheet is completely atomized are investigated. Images were reco rded with the help of a high speed camera. Primary atomization is only studied, secondaryatomization being neglected. The properties of the spray obtained by EHD atomization are investigated thoroughly, namely the breakup length, the mesh size, the drople t diameter, thedroplet count, etc.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5018 

scholarly journals Convective Air Drying Characteristics for Thin Layer Carrots

2013 ◽  
Vol 70 (2) ◽  
pp. 129 ◽  
Author(s):  
Ionut Dumitru Velescu ◽  
Ioan Tenu ◽  
Petru Carlescu ◽  
Vasile Dobre
Keyword(s):  
Air Flow ◽  
Effective Diffusivity ◽  
Food Preservation ◽  
Convective Drying ◽  
Drying Time ◽  
Drying Characteristics ◽  
Simulation And Optimization ◽  
Hot Air ◽  
Pre Treatment ◽  
Air Flow Velocity

Introduction: Carrot is one of the most commonly used vegetables for human nutrition due to high vitamin and fibre content. Drying is one of the oldest methods of food preservation, and it represents a very important aspect of food processing. Sun drying is the most common method used to preserve agricultural products in most tropical countries; this technique is extremely weather dependent, and has the problems of contamination with dust, soil, sand particles and insects. Also, the required drying time can be quite long. Therefore, using solar and hot-air dryers, which are far more rapid, providing uniformity and hygiene are inevitable for industrial food drying processes. Aim: This paper presents a kinetic study of convective drying without pre-treatment of carrot. The effects of the temperature of the drying agent, the speed of the drying agent and the thickness of the kinetics of drying the sample of carrots were investigated. Materials and methods: The experiments were carried out with the aid of an installation for drying food products, that is capable of ensuring the temperature of the drying agent (air) in the range of +25 ... +125 °C. The drying process was conducted at temperature of 45 °C in first hour of process, 2 hours at 55 °C, and 3 hours at 60 °C. The air velocity was setup  at 1.0 - 2.5 m/s. Carrots were divided into segments of a thickness of 0.4 cm. Two mathematical models available in the literature were fitted to the experimental data. Results: The drying rate increases with temperature and decreases with the sample diameter. The Page model is given better prediction than the Henderson and Pabis model and satisfactorily described drying characteristics of carrot slices. Conclusions: The most important characteristics of carrot required for simulation and optimization of the drying were studied. The values of calculated effective diffusivity for drying at 45, 55 and 60oC of air temperature and 1.0, 1.5, 2.0 and 2.5 m/s of air flow velocity. The effective diffusivity increases as air-flow rate and temperature increases. Page’s empirical model showed a good fit curves than the Henderson and Pabis model.

The Analysis of Intake Manifold Air Stream Velocity on Different Material Roughness

2014 ◽  
Vol 661 ◽  
pp. 143-147
Author(s):  
Muhammad Arif Abdul Hamid Pahmi ◽  
Sharzali Che Mat ◽  
Ahmad Nazri Nasruddin ◽  
Mohd Fauzi Ismail ◽  
Mohd Najib Yusof
Keyword(s):  
Surface Roughness ◽  
Cast Iron ◽  
Air Flow ◽  
Three Dimensional ◽  
Internal Surface ◽  
Intake Manifold ◽  
Stream Velocity ◽  
Air Stream ◽  
Air Flow Velocity ◽  
Primary Materials

Intake manifold is a crucial part in an engine that acts as a medium for air flow to mix with the fuel before entering the combustion chamber. For years, cast iron and aluminium were the primary materials chosen for fabrication of an intake manifold before plastic based material was introduced to the field. However, there is lack of research involving the usage of plastic as the intake manifold material. In this paper, the effects of internal surface roughness variations (Cast iron, aluminium and plastic) inside the intake manifold were studied. Three dimensional, intake manifold model was developed to simulate the airflow. The study emphasized on the airflow velocity inside the intake manifold. The study showed that the surface roughness influenced the air flow velocity near the intake manifold outlet. The plastic based intake manifold exhibited the highest air stream velocity (near the intake manifold outlet) at 477.770 m/s. This value is 0.60% and 0.40% higher than those produced by the cast iron and aluminium intake manifold, respectively.

scholarly journals Analysis of air flow velocity distribution in the intake system of an SI engine

2017 ◽  
Vol 169 (2) ◽  
pp. 152-157
Author(s):  
Szymon KOŁODZIEJ ◽  
Grzegorz LIGUS ◽  
Jarosław MAMALA ◽  
Andrzej AUGUSTYNOWICZ
Keyword(s):  
Air Flow ◽  
Intake Manifold ◽  
Si Engine ◽  
Work Time ◽  
Flow Disturbances ◽  
Flow Through ◽  
Load Simulator ◽  
Air Flow Velocity ◽  
Main Component ◽  
Time Density

The conditions of air flow in the intake determine power generated by the engine to a large extent. The biggest resistances in flow of the air sucked or pumped into the engine are generated by the throttle, which is at the same time the main component which allows for regulation of engine power. For the purpose of research conducted in this work, time density of engine work points in analyzed velocity profiles was determined with the use of Engine Road Load Simulator. Thanks to the knowledge of time velocity, it was possible to determine throttle positions at which the engine operates most frequently. With the use of image analysis methods, obtained parameters were experimentally researched, considering flow disturbances which are the effect of air flow through the throttle and uneven air distribution in the intake manifold of a four-cylinder engine.

EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

2018 ◽  
pp. 51-58
Author(s):  
B. P. Khozyainov
Keyword(s):  
Wind Turbine ◽  
Flow Velocity ◽  
Wind Power ◽  
Wind Turbines ◽  
Power Efficiency ◽  
Air Flow ◽  
Geometrical Parameters ◽  
Wind Speeds ◽  
Analytical Studies ◽  
Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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