ChemInform Abstract: THE PRESSURE DROP OF PERFORATED PLATES OF EXTREMELY LOW FREE AREA AND OPENING DIAMETER

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

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Computational and Experimental Study on Pressure Drop in a Fluidised Bed with Different Air Distributor Designs

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.2.2020.22.0603 ◽

2020 ◽

Vol 17 (2) ◽

pp. 8043-8051

Author(s):

A. S. M. Yudin ◽

A. N. Oumer ◽

N. F. M. Roslan ◽

M. A. Zulkarnain

Keyword(s):

Pressure Drop ◽

Perforated Plate ◽

Area Ratio ◽

Maximum Pressure ◽

Fluidised Bed ◽

Key Factor ◽

Minimum Number ◽

Maximum Pressure Drop ◽

Free Area ◽

Distributor Plate

Fluidised bed combustion (FBC) has been recognised as a suitable technology for converting a wide variety of fuels into energy. In a fluidised bed, the air is passed through a bed of granular solids resting on a distributor plate. Distributor plate plays an essential role as it determines the gas-solid movement and mixing pattern in a fluidised bed. It is believed that the effect of distributor configurations such as variation of free area ratio and air inclination angle through the distributor will affect the operational pressure drop of the fluidised bed. This paper presents an investigation on pressure drop in fluidised bed without the presence of inert materials using different air distributor designs; conventional perforated plate, multi-nozzles, and two newly proposed slotted distributors (45° and 90° inclined slotted distributors). A 3-dimensional Computational Fluid Dynamics (CFD) model is developed and compared with the experimental results. The flow model is based on the incompressible isothermal RNG k-epsilon turbulent model. In the present study, systematic grid-refinement is conducted to make sure that the simulation results are independent of the computational grid size. The non-dimensional wall distance, is examined as a key factor to verify the grid independence by comparing results obtained at different grid resolutions. The multi-nozzles distributor yields higher distributor pressure drop with the averaged maximum value of 749 Pa followed by perforated, 45° and 90° inclined distributors where the maximum pressure drop recorded to be about one-fourth of the value of the multi-nozzles pressure drop. The maximum pressure drop was associated with the higher kinetic head of the inlet air due to the restricted and minimum number of distributor openings and low free area ratio. The results suggested that low-pressure drop operation in a fluidised bed can be achieved with the increase of open area ratio of the distributor.

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Effect of chamfer geometry on the pressure drop of perforated plates with thin orifices

Nuclear Engineering and Design ◽

10.1016/j.nucengdes.2014.12.009 ◽

2015 ◽

Vol 284 ◽

pp. 74-79 ◽

Cited By ~ 6

Author(s):

José A. Barros Filho ◽

André A.C. Santos ◽

Moysés A. Navarro ◽

Elizabete Jordão

Keyword(s):

Pressure Drop ◽

Perforated Plates

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Analysis of Fluid Flow and Heat Transfer in Corrugated Perforated Plate Fin Heat Sinks

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4052598 ◽

2021 ◽

pp. 1-30

Author(s):

Shripad A Upalkar ◽

Saksham Gakhar ◽

Shankar Krishnan

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Heat Dissipation ◽

Single Channel ◽

Perforated Plate ◽

Flow Characteristics ◽

Flow Distribution ◽

Optimum Number ◽

Perforated Plates ◽

Optimum Diameter

Abstract This paper reports a mathematical model for predicting the fluid and heat flow characteristics of a Z-shaped corrugated perforated plate heat sink. Experiments were carried out to validate overall pressure drop as well as heat transfer predictions. A two-pronged approach was undertaken to design a corrugated perforated fin geometry: (a) macroscopic packaging, where the flow is distributed into conduits before being fed into perforated plates, and (b) microscopic design, where the pores are sized to maximize heat dissipation. A methodology typically used for predicting flow maldistribution is extended for packaging porous perforated plates in the macroscopic approach. An illustrative study is carried that estimates the optimum number of porous perforated plate fins that can be packaged within a given volume under fixed pressure drop constraint. In the microscopic approach, an order of magnitude analysis was carried out to decide the optimum diameter to maximize the heat transfer rate and expression for optimum diameter, and maximum achievable heat flux is proposed. Numerical simulations were carried out by considering full perforated plate porous fin geometry and single-channel geometry, and good agreement in their results was found. Finally, this study elaborates on the importance of achieving uniform flow distribution across the porous perforated plate fins.

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Cavitation Inception and Head Loss Due to Liquid Flow Through Perforated Plates of Varying Thickness

Journal of Fluids Engineering ◽

10.1115/1.4023407 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 19

Author(s):

D. Maynes ◽

G. J. Holt ◽

J. Blotter

Keyword(s):

Plate Thickness ◽

Area Ratio ◽

Diameter Ratio ◽

Hole Diameter ◽

Loss Coefficient ◽

Perforated Plates ◽

Cavitation Inception ◽

Perforation Hole ◽

Critical Cavitation ◽

Free Area

This paper reports results of an experimental investigation of the loss coefficient and onset of cavitation caused by water flow through perforated plates of varying thickness and flow area to pipe area ratio at high speeds. The overall plate loss coefficient, point of cavitation inception, and point where critical cavitation occurs are functions of perforation hole size, number of holes, and plate thickness. Sixteen total plates were considered in the study with the total perforation hole area to pipe area ratio ranging from 0.11 and 0.6, the plate thickness to perforation hole diameter ranging from 0.25 to 3.3, and the number of perforation holes ranging from 4 to 1800. The plates were mounted in the test section of a closed water flow loop. The results reveal a complex dependency between the plate loss coefficient with total free-area ratio and the plate thickness to perforation hole diameter ratio. In general, the loss coefficient decreases with increasing free-area ratio and increasing thickness-to-hole diameter ratio. A model based on the data is presented that predicts the loss coefficient for multiholed perforated plates with nonrounded holes. Furthermore, the data show that the cavitation number at the points of cavitation inception and critical cavitation increases with increasing free-area ratio. However, with regard to the thickness-to-hole diameter ratio, the cavitation number at inception exhibits a local maximum at a ratio between 0.5 and 1.0. Empirical models to allow prediction of the point of cavitation inception and the point where critical cavitation begins are presented and compared to single hole orifice plate behavior.

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Numerical Prediction of Homogeneity of Gas Flow through Perforated Plates

Processes ◽

10.3390/pr9101770 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1770

Author(s):

Kamil Śmierciew ◽

Dariusz Butrymowicz ◽

Jarosław Karwacki ◽

Jerzy Gagan

Keyword(s):

Pressure Drop ◽

Gas Flow ◽

Numerical Models ◽

Perforated Plate ◽

Total Surface Area ◽

Structural Elements ◽

Open Area ◽

Perforated Plates ◽

Porous Media Model ◽

Flow Through

Vanes and baffles are often used as flow distributors where uniform flow is required in the apparatus of large cross-section surface areas. As an alternative, perforated plates with a range of open area ratios are applied to produce required gas flow homogeneity. Usually, the plates with various open area ratios are combined into large panels, of which total surface area can reach hundreds of square meters for large-sized industrial apparatus. Numerical modelling of the flow through such panels can be thought of as overly complex, time-consuming, and inefficient due to numerous small open area ratios in the plates and large differences in dimensions between open area ratios and free-stream areas. For this reason, numerical models of gas flow are limited to single plates only with constant open area ratios. A new indirect modelling approach of gas flow through the perforated plates panel with structural elements and various open area ratios with application of the porous media model is proposed. A perforated plate was experimentally investigated in terms of pressure drop and velocity distribution. The data obtained were used for the validation of the numerical results, which differed from the experimental results by less than 5%. In the next step, numerical analyses were performed for plates with open area ratios in the range of 30 to 70% for gas velocities of 5 and 10 m/s. A general correlation for pressure drop as a function of open area ratio was proposed. Finally, systematic numerical studies of the flow through both perforated and porous plates including structural elements were performed. The internal resistance of the porous core was calculated by means of a developed correlation. A good agreement between results with an error lower than 15% was observed.

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Performance and Potential of Perforated Plates as a Heat Transfer Surface

ASME 1968 Gas Turbine Conference and Products Show ◽

10.1115/68-gt-33 ◽

1968 ◽

Cited By ~ 1

Author(s):

H. H. Osborn ◽

R. K. Shah ◽

R. J. H. Liljelund ◽

P. C. Wolf ◽

R. Eichhorn

Keyword(s):

Heat Transfer ◽

Flow Visualization ◽

Gas Turbine ◽

Parallel Plate ◽

Flow Behavior ◽

Heat Transfer Surface ◽

Perforated Plates ◽

Friction Characteristics ◽

Flow Friction ◽

Free Area

The heat transfer and flow friction characteristics of a number of parallel plate surfaces with round or slotted perforations are presented. Their performance is compared to the parallel nonperforated plate as a standard and is shown to be very promising in terms of reducing the free area of volume of gas turbine regenerators. Sound and vibration phenomena were observed and recorded. To gain an understanding of the flow behavior over the perforations, a scaled-up flow visualization study was performed.

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Heat Exchange Effectiveness and Pressure Drop for Air Flow Through Perforated Plates With and Without Crosswind

Journal of Heat Transfer ◽

10.1115/1.2911411 ◽

1994 ◽

Vol 116 (2) ◽

pp. 391-399 ◽

Cited By ~ 85

Author(s):

C. F. Kutscher

Keyword(s):

Heat Transfer ◽

Heat Exchange ◽

Pressure Drop ◽

Air Flow ◽

Ambient Air ◽

Perforated Plates ◽

Wind Speeds ◽

New Type ◽

Flow Through ◽

Heat Exchange Effectiveness

Low-porosity perforated plates are being used as absorbers for heating ambient air in a new type of unglazed solar collector. This paper investigates the convective heat transfer effectiveness for low-speed air flow through thin, isothermal perforated plates with and without a crosswind on the upstream face. The objective of this work is to provide information that will allow designers to optimize hole size and spacing. In order to obtain performance data, a wind tunnel and small lamp array were designed and built. Experimental data were taken for a range of plate porosities from 0.1 to 5 percent, hole Reynolds numbers from 100 to 2000, and wind speeds from 0 to 4 m/s. Correlations were developed for heat exchange effectiveness and also for pressure drop. Infrared thermography was used to visualize the heat transfer taking place at the surface.

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