scholarly journals Influence of Friction Factor and Flow Equation on Calculation of Gas-Distribution Pipeline Networks

2018 ◽  
Author(s):  
Dejan Brkić
Keyword(s):  
Friction Factor ◽  
Gas Flow ◽  
Flow Equation ◽  
Gas Distribution ◽  
Pipeline Networks ◽  
Hardy Cross ◽  
Accurate Procedure ◽  
Selection Of

Here is shown method for the hydraulic solution of a looped gas-pipeline networks. Calculation of presented network is done according to principles of Hardy Cross method. The optimization was carried out by iteration of the pipes diameters, node consumptions are known and flow velocities through pipes have to stand below certain values. Accent is on determination of appropriate friction factor, and on selection of representative equation for natural gas flow under presented conditions in the network. Inappropriate usage of friction factor, equally as inappropriate usage of gas flow equation can lead to inaccurate final results. Here is shown new facts in comparison to previous calculation of gas distribution network in Kragujevac, Serbia which is done in 1994. After the implementation, measurements in situ have performed, and real measured values deviate from calculated. Causes for these errors are investigated, and improved and more accurate procedure is shown.

scholarly journals A Gas Distribution Network Hydraulic Problem from Practice

2017 ◽  
Author(s):  
D. Brikić
Keyword(s):  
Natural Gas ◽  
Friction Factor ◽  
Gas Flow ◽  
Optimization Problem ◽  
Distribution Network ◽  
Gas Distribution ◽  
Pipeline Network ◽  
Hardy Cross ◽  
Selection Of

Accent is on determination of appropriate friction factor, and on selection of representative equation for natural gas flow under presented conditions in the network. Calculation of presented looped gas-pipeline network is done according to principles of Hardy Cross method. The final flows were calculated, for known pipes diameters and nodes consumptions while the flow velocities through pipes have to stand below certain values. In optimization problem flows are treated as constant, while the diameters are variables.

scholarly journals Similarities and Differences in Optimization of Water- and Gas- Distribution Pipeline Networks

2018 ◽  
Author(s):  
Dejan Brkić
Keyword(s):  
Natural Gas ◽  
Friction Factor ◽  
Gas Flow ◽  
Flow Equations ◽  
Water Pipelines ◽  
Pipeline Networks ◽  
Hardy Cross ◽  
Simple Network ◽  
Selection Of

Accent is on determination of appropriate friction factor of the pipes and on selection of the representative equation for water or natural gas flow which is valuable for existing conditions in the looped network of pipelines. Note that in a municipal gas pipeline, natural gas can be treated as incompressible fluid (liquid) i.e. as water or oil. Even under this circumstance, calculation of water pipelines cannot be literary copied and applied for calculation of gas pipelines. Inappropriate friction factor, equally as e.g. inappropriate usage of water flow equations for calculation of gas networks can lead to inaccurate final results. Few iterative methods for determining the optimal hydraulic solution of water- and gas- looped pipeline networks, such as, Hardy Cross, modified Hardy Cross, node-loop method, node and M.M. Andrijashev method, will be shown. Speed of convergence will be compared and discussed using a simple network with three loops.

scholarly journals An improvement of Hardy Cross method applied on looped spatial natural gas distribution networks

2017 ◽  
Author(s):  
Dejan Brkic
Keyword(s):  
Gas Flow ◽  
Solution Method ◽  
Distribution Networks ◽  
Original Method ◽  
Gas Distribution ◽  
Gas Network ◽  
Hardy Cross ◽  
Successive Substitution ◽  
Newton Raphson ◽  
Looped Network

Hardy Cross method is common for calculation of loops-like gas distribution networks with known node gas consumptions. This method is given in two forms: original Hardy Cross method-successive substitution methods and improved-simultaneous solution method (Newton-Raphson group of methods). Problem of gas flow in looped network is nonlinear problem; i.e. relation between flow and pressure drop is not linear while relation between electric current and voltage is. Improvement of original method is done by introduction of influence of adjacent contours in Yacobian matrix which is used in calculation and which is in original method strictly diagonal with all zeros in non-diagonal terms. In that way necessary number of iteration in calculations is decreased. If during the design of gas network with loops is anticipated that some of conduits are crossing each other without connection, this sort of network became, so there has to be introduced corrections of third or higher order.

scholarly journals KPIM of Gas Transportation: Robust Modification of Gas Pipeline Equations

2008 ◽  
Vol 45 (5) ◽  
pp. 39-47
Author(s):  
A. Falade ◽  
A. Olaberinjo ◽  
M. Oyewola ◽  
F. Babalola ◽  
S. Adaramola
Keyword(s):  
Friction Factor ◽  
Gas Flow ◽  
Research Work ◽  
Flow Equation ◽  
Gas Pipeline ◽  
Flow Rates ◽  
Modified Equations ◽  
Wide Range ◽  
High Degree ◽  
Turbulent Gas Flow

KPIM of Gas Transportation: Robust Modification of Gas Pipeline Equations Studies of the flow conditions of natural gases in pipelines have led to the development of complex equations for relating the volume transmitted through a gas pipeline to the various factors involved, thus deciding the optimum pressures and pipeline dimensions to be used. From equations of this type, various combinations of pipe diameter and wall thickness for a desired rate of gas throughput can be calculated. This research work presents modified forms of the basic gas flow equation for horizontal flow developed by Weymouth and the basic gas flow equation for inclined flow developed by Ferguson. The modified equations incorporate non-iterative forms of the Colebrook-White friction factor into the original forms of the Weymouth's and Ferguson's equations. These modified equations thus eliminate the need for iteration in predicting the flow rate of gas through pipelines as is the case with their original forms when the Colebrook-White friction factor is used. The modified equations also have a wider range of application since the Colebrook-White friction factor is valid for turbulent gas flow as well as for gas flow in a transition zone. On comparing the results it can be seen that the modified Ferguson's equation gives a more accurate prediction of gas flow rates because it takes the pipeline elevation into account. Lower deviations from measured gas flow rates were observed with the modified Ferguson's equation than with the modified basic gas flow equation. The deviations observed using the modified Ferguson equation were found to range from -0.16% to +3.21%. Conclusively, these less cumbersome newly developed equations with high degree reliability will be useful in predicting the rates of gas flow for a wide range of its conditions, pipeline elevation and pipeline lengths.

Determination of mechanical properties of artificial turf football pitches according to structural components

2017 ◽  
Vol 232 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Javier Sánchez-Sánchez ◽  
Pascal Haxaire ◽  
Jorge García Unanue ◽  
José L Felipe ◽  
Ana M Gallardo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Structural Parameters ◽  
Base Material ◽  
Structural Components ◽  
Artificial Turf ◽  
Force Reduction ◽  
Pile Length ◽  
Selection Of

Structural components of artificial turf football pitches have been improved in the last decade. The aim of this study was to explore the influence of structural components on the in situ mechanical behaviour of third-generation artificial turf football pitches. In total, 21 pitches were analysed according to the specified FIFA procedures. The results revealed that each of the pitches complies with the requirements of FIFA regulations. Pile length sample, stabilising bulk density, tuft/m2 and sub-base material all demonstrated a significant influence on the mechanical properties of the surface ( p < 0.05). Finally, the selected structural parameters explained 77.9%, 59.8% and 54.3% of variance in rotational traction, vertical deformation and force reduction, respectively. These results show the importance of the selection of the structural components in the design of artificial turf football pitches.

Determination of Pipe Roughness and Heat Transfer Coefficient in Pipeline Networks Using Multidomain Solution Method

1998 ◽  
Author(s):  
Jaroslaw Jelen ◽  
Hossein Golshan ◽  
Sandy Rizopoulos
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Parameter Identification ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Gas Flow ◽  
Solution Method ◽  
Accurate Determination ◽  
Pipeline System

In the development of new pipeline projects, all too often assumptions that are made in the initial stages of the business development opportunity are, for the most part, overly conservative. This inaccuracy is carried out through to the operation of the pipeline system and most assumptions do not change with subsequent expansions in the future until a conscious effort is made to determine and monitor those significant parameters that impact the pipeline’s overall performance. In highly complex systems such as NOVA Gas Transmission Ltd.’s (NGTL’s) pipeline network, with over 21400 Km of pipe segments of different sizes and ages, for an accurate determination of pressure drop while 12 BCF of gas, on average, is flowing through our network, we need a technique to precisely assess the values of friction factor and heat transfer coefficient. These values have a profound impact on the accuracy of the hydraulic simulations. The calculated values of pressure, flow rate, and temperature may be distorted by imprecise values of some parameters, such as friction factor or heat transfer coefficient. Thus, a proper estimation of these parameters is of great importance to the successful numerical flow simulation. Both friction factor and heat transfer coefficient are very difficult to measure; therefore, their values can only be assessed by solving an inverse problem (i.e. parameter identification process). Since the parameter estimation procedure reported in this paper requires multiple solution of inviscid gasdynamics differential equations, describing the gas flow through the pipeline system, a multidomain solution method has been applied to effectively solve the parameter identification problem.

scholarly journals Morphological and microsatellite analysis of the ancient Montenegrin olive variety ‘Žutica’ revealed different clones

2020 ◽  
Vol 116 (2) ◽  
pp. 205
Author(s):  
Mirjana ADAKALIĆ ◽  
Biljana LAZOVIĆ ◽  
Alenka BARUCA ARBEITER ◽  
Matjaž HLADNIK ◽  
Jernej JAKŠE ◽  
...  
Keyword(s):  
Morphological Traits ◽  
Principal Component ◽  
Geographic Region ◽  
Group Method ◽  
Pair Group ◽  
Olive Variety ◽  
Olive Varieties ◽  
Selection Of

<p>The ‘Žutica’ represents the most common Montenegrin olive varieties mainly used for the production of olive oil and green and black fruit canning. Traditionally, the olive plants have been propagated vegetatively, and a small level of genetic polymorphism is expected among clones of the same variety. This topic was only partially studied in the Montenegrin olive ‘Žutica’. Therefore, this study aimed to determine intra-varietal genetic variability in twenty-three ‘Žutica’ trees selected in situ, analyzing the variability of morphological traits and microsatellites. The Principal Component Analyses (PCA) with six axes explains the total cumulative variance of 91.3 %, with fruit and endocarp traits in the first three PC. The unweighted pair group method with arithmetic mean of twenty morphological traits grouped ‘Žutica’ trees into two clusters and five independent trees. Nine microsatellite primers amplified 31 fragments of which 22 were polymorphic and enabled the detection of nine different microsatellite profiles (potential different clones). A comparison of dendrogram groups based on morphological and microsatellite markers showed low cophenetic values in the determination of intra-varietal variability. The results showed that the old variety ‘Žutica’, from a relatively small geographic region, has a variable genetic base, which could be used in the selection of superior clones.</p>

Patient Selection and Appliance Design in Intra-oral Models

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 908-910 ◽  
Author(s):  
J.M. Ten Cate
Keyword(s):  
Clinical Trials ◽  
Patient Selection ◽  
Short Review ◽  
Model Systems ◽  
Experimental Conditions ◽  
In Situ Studies ◽  
Different Types ◽  
Selection Of

The conclusions derived from in situ studies are influenced by the choices made with respect to parameters of the intra-oral model systems. In an attempt to reach a consensus, this paper considers the variables (a) selection of panelists and (b) appliance design. On both topics, a short review of available systems is given. The objectives of the intra-oral study may vary from the determination of oral physiological parameters to assessment of the effects of caries-preventive treatments. This objective is a factor influencing the choice of experimental conditions. Recommendations for panelist selection and appliance design are given for different types of studies. It is concluded that relatively little information is available about the effects of individual parameters on the performance of a model. Therefore, for an assessment of caries-preventive effectiveness, an intra-oral model should be validated against clinical trials. In addition, conditions should be chosen such as to limit the degree of artificiality of the model.

scholarly journals NON-DESTRUCTIVE METHOD FOR RAPID "IN SITU" CHARACTERIZATION OF ROCKS

2004 ◽  
Vol 36 (4) ◽  
pp. 1912
Author(s):  
N. Ciornei ◽  
I. Facaoaru ◽  
V. Cetean
Keyword(s):  
Quality Criteria ◽  
In Situ Characterization ◽  
Hard Rocks ◽  
Determination Process ◽  
Building Activity ◽  
Non Destructive ◽  
Selection Of

The effective determination of the field and place of application of the products resulting from stone working is a compulsory requirement in the building activity and is solved by laboratory analyses. This article presents details on the determination, by non-destructive method, of the compression strength of the rocks, both "in situ" (in the deposit) and in a laboratory. The originality of the method consists in simplifying the determination process of this parameter, a method that is in agreement with the systems proposed to be applied in the European Community. The method has the advantage of being applicable in quarries, where knowledge of this parameter leads to a rationalizing of the working and more especially to a selection of the blocks by quality criteria. The method is applicable to all categories of natural consolidated hard rocks, being a viable alternative for deposits with an inhomogeneous composition as to quality and structure.

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