Pressure Drop in Solar Power Plant Chimneys

Solar Energy ◽  
2002 ◽  
Author(s):  
Theodore W. von Backstro¨m ◽  
Andreas Bernhardt ◽  
Anthony J. Gannon
Keyword(s):  
Pressure Drop ◽  
Wall Friction ◽  
Rectangular Section ◽  
Pressure Drops ◽  
Through Flow ◽  
Radial Spokes ◽  
Friction Pressure Drop ◽  
Internal Bracing ◽  
Order Of Magnitude ◽  
Flow Through

The paper investigates the flow through a representative tall solar chimney with seven sets of internal bracing wheels with radial spokes. The paper presents experimental data measured in a 0.63 m diameter laboratory scale chimney model with and without bracing wheels. A fan at one end of the chimney model either sucked or blew the flow through it. The measured friction pressure drop was higher than theoretical values for smooth walls, and swirling, blown flow increased it by another 12%. The seven bracing wheels, each had twelve spokes, each spoke consisting of a pair of rectangular section bars, caused order of magnitude larger pressure drops than wall friction. For the sucked-through flow the forced, swirling, disturbed flow increased the pressure drop by up to 36%. Bracing wheels also increased the exit kinetic energy coefficient to 1.26 with the last wheel at the chimney exit. This effect could in combination with the bracing wheel drag reduce flow through the chimney. Designers of large chimneys should take care to minimise the number of bracing wheels, and possibly to streamline spoke sections. If possible, the top bracing wheel should be far enough from the exit for the flow to reattach to the wall after passing over the spoke attachment rim at the wall.

Pressure Drop in Solar Power Plant Chimneys

2003 ◽  
Vol 125 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Theodor W. von Backstro¨m ◽  
Andreas Bernhardt ◽  
Anthony J. Gannon
Keyword(s):  
Pressure Drop ◽  
Kinetic Energy ◽  
Separated Flow ◽  
Wall Friction ◽  
Solar Chimney ◽  
Rectangular Section ◽  
Frictional Pressure Drop ◽  
Internal Bracing ◽  
Flow Through ◽  
Kinetic Energy Loss

The paper investigates flow through a representative tall solar chimney with internal bracing wheels. It presents experimental data measured in a 0.63-m-dia model chimney with and without seven bracing wheels. The bracing wheels each had a rim protruding into the chimney and 12 spokes, each spoke consisting of a pair of rectangular section bars. The investigation determined coefficients of wall friction, bracing wheel loss, and exit kinetic energy in a model chimney, for both ideal non-swirling uniform flow and for swirling distorted flow. A fan at one end of the chimney model either sucked or blew the flow through it. The flow entering the chimney through the fan and its diffuser simulated the flow leaving the turbine at the bottom of the chimney. The swirling distorted flow increased the total pressure drop by about 28%, representing 4.7% of the turbine pressure drop. The pressure drop across the bracing wheels exceeded the frictional pressure drop by far. Designers of tall, thin-walled chimneys should take care to minimize the number of bracing wheels, reduce their rim width as much as possible, and investigate the feasibility of streamlining their spoke sections. If at all structurally possible, the top bracing wheel should be far enough from the chimney exit to allow the spoke wakes to decay and the separated flow to re-attach to the chimney wall downstream of the rims before the flow leaves the chimney, to reduce the exit kinetic energy loss.

Compressible Flow Through Solar Power Plant Chimneys

2000 ◽  
Vol 122 (3) ◽  
pp. 138-145 ◽  
Author(s):  
Theodor W. von Backstro¨m ◽  
Anthony J. Gannon
Keyword(s):  
Pressure Drop ◽  
Compressible Flow ◽  
Power Plants ◽  
Step Length ◽  
Wall Friction ◽  
Vertical Acceleration ◽  
Through Flow ◽  
Flow Through ◽  
Thermodynamic Variables ◽  
Additional Losses

Chimneys as tall as 1500 m may be important components of proposed solar chimney power plants. The exit air density will then be appreciably lower than the inlet density. The paper presents a one-dimensional compressible flow approach for the calculation of all the thermodynamic variables as dependent on chimney height, wall friction, additional losses, internal drag and area change. The method gives reasonable answers even over a single 1500 m step length used for illustration, but better accuracy is possible with multiple steps. It is also applicable to the rest of the plant where heat transfer and shaft work may be present. It turns out that the pressure drop associated with the vertical acceleration of the air is about three times the pressure drop associated with wall friction. But flaring the chimney by 14 percent to keep the through-flow Mach number constant virtually eliminates the vertical acceleration pressure drop. [S0199-6231(00)03003-3]

Viscous flow in a cylindrical tube containing a line of spherical particles

1969 ◽  
Vol 38 (1) ◽  
pp. 75-96 ◽  
Author(s):  
Henry Wang ◽  
Richard Skalak
Keyword(s):  
Pressure Drop ◽  
Cylindrical Tube ◽  
Tube Diameter ◽  
Creeping Flow ◽  
Spherical Particles ◽  
Sphere Diameter ◽  
Wide Range ◽  
Mean Pressure ◽  
Order Of Magnitude ◽  
Flow Through

The viscous, creeping flow through a cylindrical tube of a liquid, which contains rigid, spherical particles, is investigated analytically. The spheres are located on the axis of the cylinder and are equally spaced. Solutions are derived for particles in motion and fixed, with and without fluid discharge. Numerical results are presented for the drag on each sphere and the mean pressure drop for a wide range of sizes and spacings of the spheres. The study is motivated by possible application to blood flow in capillaries, where red blood cells represent particles of the same order of magnitude as the diameter of the capillary itself. The results may also be of interest in other applications, such as sedimentation and fluidized beds. It is shown that there is little interaction between particles if the spacing is more than one tube diameter, and that the additional pressure drop over that for Poiseuille flow is less than 50% if the sphere diameter is less than 0·8 of the tube diameter.

A Series Pressure Drop Representation for Flow Through Orifice Tubes

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
T. A. Jankowski ◽  
E. N. Schmierer ◽  
F. C. Prenger ◽  
S. P. Ashworth
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Simple Model ◽  
Pressure Drop ◽  
Diameter Ratio ◽  
Pressure Drops ◽  
In Series ◽  
Orifice Flow ◽  
Flow Through ◽  
Length To Diameter Ratio

A simple model is developed here to predict the pressure drop and discharge coefficient for incompressible flow through orifices with length-to-diameter ratio greater than zero (orifice tubes) over wide ranges of Reynolds number. The pressure drop for flow through orifice tubes is represented as two pressure drops in series; namely, a pressure drop for flow through a sharp-edged orifice in series with a pressure drop for developing flow in a straight length of tube. Both of these pressure drop terms are represented in the model using generally accepted correlations and experimental data for developing flows and sharp-edged orifice flow. We show agreement between this simple model and our numerical analysis of laminar orifice flow with length-to-diameter ratio up to 15 and for Reynolds number up to 150. Agreement is also shown between the series pressure drop representation and experimental data over wider ranges of Reynolds number. Not only is the present work useful as a design correlation for equipment relying on flow through orifice tubes but it helps to explain some of the difficulties that previous authors have encountered when comparing experimental observation and available theories.

Inlet and Outlet Pressure-Drop Effects on the Determination of Permeability and Form Coefficient of a Porous Medium

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
C. Naaktgeboren ◽  
P. S. Krueger ◽  
J. L. Lage
Keyword(s):  
Porous Medium ◽  
Pressure Drop ◽  
Parallel Plates ◽  
Pressure Drops ◽  
Outlet Pressure ◽  
Medium Length ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
Definition Of

The determination of permeability K and form coefficient C, defined by the Hazen-Dupuit-Darcy (HDD) equation of flow through a porous medium, requires the measurement of the total pressure drop caused by the porous medium (i.e., inlet, core, and outlet) per unit of porous medium length. The inlet and outlet pressure-drop contributions, however, are not related to the porous medium length. Hence, for situations in which these pressure drops are not negligible, e.g., for short or very permeable porous media core, the definition of K and C via the HDD equation becomes ambiguous. This aspect is investigated analytically and numerically using the flow through a restriction in circular pipe and parallel plates channels. Results show that inlet and outlet pressure-drop effects become increasingly important when the inlet and outlet fluid surface-fraction φ decreases and the Reynolds number Re increases for both laminar and turbulent flow regimes. A conservative estimate of the minimum porous medium length beyond which the core pressure drop predominates over the inlet and outlet pressure drop is obtained by considering a least restrictive porous medium core. Finally, modified K and C are proposed and predictive equations, accurate to within 2.5%, are obtained for both channel configurations with Re ranging from 10−2 to 102 and φ from 6% to 95%.

Single-Phase and Two-Phase Flow Through Thin and Thick Orifices in Horizontal Pipes

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Manmatha K. Roul ◽  
Sukanta K. Dash
Keyword(s):  
Pressure Drop ◽  
Single Phase ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Orifice Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Horizontal Pipes ◽  
Flow Through

Two-phase flow pressure drops through thin and thick orifices have been numerically investigated with air–water flows in horizontal pipes. Two-phase computational fluid dynamics (CFD) calculations, using the Eulerian–Eulerian model have been employed to calculate the pressure drop through orifices. The operating conditions cover the gas and liquid superficial velocity ranges Vsg = 0.3–4 m/s and Vsl = 0.6–2 m/s, respectively. The local pressure drops have been obtained by means of extrapolation from the computed upstream and downstream linearized pressure profiles to the orifice section. Simulations for the single-phase flow of water have been carried out for local liquid Reynolds number (Re based on orifice diameter) ranging from 3 × 104 to 2 × 105 to obtain the discharge coefficient and the two-phase local multiplier, which when multiplied with the pressure drop of water (for same mass flow of water and two phase mixture) will reproduce the pressure drop for two phase flow through the orifice. The effect of orifice geometry on two-phase pressure losses has been considered by selecting two pipes of 60 mm and 40 mm inner diameter and eight different orifice plates (for each pipe) with two area ratios (σ = 0.73 and σ = 0.54) and four different thicknesses (s/d = 0.025–0.59). The results obtained from numerical simulations are validated against experimental data from the literature and are found to be in good agreement.

scholarly journals Effect of Modification in Flow Distributor Valve Geometry on the Pressure Drop and Chamber Pressures, in Numerical and Analytical Way, in ORBIT Motor HST Unit

2018 ◽  
Author(s):  
Debanshu Roy ◽  
Amit Kumar ◽  
Rathindranath Maiti ◽  
Prasanta Kumar Das
Keyword(s):  
Mathematical Model ◽  
Pressure Drop ◽  
Cfd Analysis ◽  
Pressure Drops ◽  
Comprehensive Knowledge ◽  
Flow Interactions ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Spool Valve ◽  
Flow Distributor

In this paper, an attempt has been made to analyze the effect of spool port/ groove geometry on the pressure drop and chamber pressures which effect the performance parameters of the flow distributor valve. The work mainly involves formulation of detailed mathematical model of the valve and compare them on the same platform. For mathematical modelling, Matlab has been used. The size of the orifices is considered same throughout the model for better comparison. Initially the construction and functioning of flow distributor valve along with working principles of hydrostatic motor (Rotary Piston) is shown. Next shown the analytical analysis of area change and pressure drops due to different geometry of the spool valve ports. After that the computational fluid dynamics (CFD) analysis has been shown. A complete mathematical model to describe such flow distributor valve is developed after having a comprehensive knowledge of orifice characteristics, flow interactions based on valve geometry. Equations of flow through different orifices (fixed and variable area) of the valve have been developed based on the relationships obtained earlier.

scholarly journals Pressure Drops in Two-Phase Gas–Liquid Flow through Channels Filled with Open-Cell Metal Foams

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2419
Author(s):  
Roman Dyga ◽  
Sebastian Brol
Keyword(s):  
Pressure Drop ◽  
Liquid Flow ◽  
Single Phase ◽  
Fluid Pressure ◽  
Metal Foams ◽  
Geometrical Parameters ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Through ◽  
Gas Liquid Flow

This paper describes experimental investigations of single-phase and two-phase gas–liquid flow through channels with a diameter of 20 mm and length of 2690 mm, filled with metal foams. Three types of aluminium foams with pore densities of 20, 30 and 40 PPI and porosities ranging from 29.9% to 94.3% were used. Air, water and oil were pumped through the foams. The tests covered laminar, transitional and turbulent flow. We demonstrated that the Reynolds number, in which the hydraulic dimension should be defined based on foam porosity and pore diameter de = ϕdp/(1 − ϕ), can be used as a flow regime assessment criterion. It has been found that fluid pressure drops when flowing through metal foams significantly depends on the cell size and porosity of the foam, as well as the shape of the foam skeleton. The flow patterns had a significant influence on the pressure drop. Among other things, we observed a smaller pressure drop when plug flow changed to stratified flow. We developed a model to describe pressure drop in flow through metal foams. As per the proposed methodology, pressure drop in single-phase flow should be determined based on the friction factor, taking into account the geometrical parameters of the foams. We propose to calculate pressure drop in gas–liquid flow as the sum of pressure drops in gas and liquid pressure drop corrected by the drop amplification factor.

scholarly journals Decision making by using a computer algorithm to analyze hydrocarbon production systems

2016 ◽  
pp. 75-83
Author(s):  
Robinson Stevens Salazar-Rúa ◽  
Johan Darío Caicedo-Reyes ◽  
Jovani Alberto Jiménez-Builes
Keyword(s):  
Pressure Drop ◽  
Production System ◽  
Production Systems ◽  
Initial Pressure ◽  
Production Costs ◽  
Hydrocarbon Production ◽  
Nodal Analysis ◽  
Pressure Drops ◽  
Flow Through ◽  
Oil Company

This paper shows an algorithm that allows to automate the procedures of nodal analysis and flow optimization in a hydrocarbon production system. The procedure of nodal analysis is highly useful in flow wells, intermittent wells or in wells with artificial production systems. The nodal analysis evaluates a production system divided into two basic components: flow through vertical piping or production piping, and flow through horizontal piping or discharge line. For the prediction of each component's behavior, the pressure drop in each component is obtained. In order to obtain the pressure drops, nodes in different important points within the production system must be assigned; therefore, production expenses can vary and, by using a suitable calculation method, the pressure drop between two nodes is calculated. Then, a node is selected and the pressure drops are added to or subtracted from the initial pressure point or departure node, until obtaining the solution node. The results obtained when using the algorithm have allowed to update both procedures, obtaining advantages such as improvement in response time, among others. This analysis is a crucial point when making decisions related to production costs in any oil company.

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