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.

SERVICEABILITY OF NATURAL GAS DISTRIBUTION NETWORKS AFTER EARTHQUAKES

2013 ◽  
Vol 07 (02) ◽  
pp. 1350005 ◽  
Author(s):  
GIAN PAOLO CIMELLARO ◽  
ALESSANDRO DE STEFANO ◽  
OMAR VILLA
Keyword(s):  
Natural Gas ◽  
Distribution Network ◽  
Distribution Networks ◽  
Small Towns ◽  
Disaster Resilience ◽  
Gas Distribution ◽  
Gas Network ◽  
Resilience Index ◽  
Entire Network

The concept of disaster resilience has received considerable attention in recent years and it is increasingly used as an approach for understanding the dynamics of natural disaster systems. No models are available in literature to measure the performance of natural gas network, therefore, in this paper, a new performance index measuring functionality of gas distribution network have been proposed to evaluate the resilience index of the entire network. It can be used for any type of natural or manmade hazard which might lead to the disruption of the system. The gas distribution network of the municipalities of Introdacqua and Sulmona, two small towns in the center of Italy which were affected by 2009 earthquake have been used as case study. Together the pipeline network covers an area of 136 km2, with 3 M/R stations and 16 regulation groups. The software SynerGEE has been used to simulate different scenario events. The numerical results showed that, during emergency, to ensure an acceptable delivery service, it is crucial to guarantee the functionality of the medium pressure gas distribution network. Instead to improve resilience of the entire network the best retrofit strategy is to include emergency shutoff valves along the pipes.

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 Gas distribution network topology problem

2017 ◽  
Author(s):  
Dejan Brkić
Keyword(s):  
Nonlinear Problem ◽  
Network Topology ◽  
Iterative Procedure ◽  
Gas Flow ◽  
Distribution Network ◽  
Gas Pipeline ◽  
Gas Distribution ◽  
Pipeline Network ◽  
Loop Matrix ◽  
Looped Network

Problem of gas flow in looped network is nonlinear problem and these kind of problemshave to be solved using some kind of iterative procedure. For the pipeline network, two topologymatrices can be written; i.e. loop matrix and node matrix. The node matrix is related to therst Kirchho's law while the loop matrix is related to second Kirchho's law. Here will beshown ecient method in which both matrices, i.e. the node and the loop matrix are unitedin one coherent procedure for solution of looped gas pipeline problem.

scholarly journals Hardy Cross Method for Pipe Networks

2019 ◽  
Author(s):  
Dejan Brkić ◽  
Pavel Praks
Keyword(s):  
Flow Resistance ◽  
Water Pipe ◽  
Pipe Network ◽  
Pipe Networks ◽  
Hardy Cross ◽  
Hydraulic Networks ◽  
Newton Raphson ◽  
Balanced Solution ◽  
Number Of Iterations ◽  
Looped Network

Hardy Cross originally proposed a method for analysis of flow in networks of conduits or conductors in 1936. His method was the first really useful engineering method in the field of pipe network calculation. Only electrical analogs of hydraulic networks were used before the Hardy Cross method. A problem with the flow resistance versus the electrical resistance makes these electrical analog methods obsolete. The method by Hardy Cross is taught extensively at faculties and it still remains an important tool for analysis of looped pipe systems. Engineers today mostly use a modified Hardy Cross method which threats the whole looped network of pipes simultaneously (use of these methods without computers is practically impossible). A method from the Russian practice published during 1930s, which is similar to the Hardy Cross method, is described, too. Some notes from the life of Hardy Cross are also shown. Finally, an improved version of the Hardy Cross method, which significantly reduces number of iterations, is presented and discussed. Also we tested multi-point iterative methods which can be used as substitution for the Newton-Raphson approach used by Hardy Cross, but this approach didn’t reduce number of required iterations to reach the final balanced solution. Although, many new models have been developed since the time of Hardy Cross, main purpose of this paper is to illustrate the very beginning of modeling of gas and water pipe networks or ventilation systems.

Improving Thermal-Hydraulic Calculation Modules of THERMIX Code Based on LU Decomposition

2013 ◽  
Author(s):  
Yang Tang ◽  
Yangping Zhou ◽  
Zhiwei Zhou
Keyword(s):  
Gas Flow ◽  
Solution Method ◽  
Solid Phase ◽  
Iterative Solution ◽  
Original Method ◽  
Hydraulic Calculation ◽  
Lu Decomposition ◽  
Safety Behavior ◽  
Calculation Module ◽  
Accident Conditions

THERMIX is a software package for analyzing the thermal-hydraulic and safety behavior of pebble-bed high temperature gas-cooled reactor under both normal condition and accident conditions. The point-wise iterative solution method of THERMIX is time-consuming and difficult to be extended. For the solid-phase thermal conductivity calculation module (THERMIX), gas flow calculation module (KONVEK) and primary loop flow network system calculation module (KISMET) respectively, a global solution method based on LU decomposition with higher efficiency is developed and tested. With good calculation accuracy, the new method has a greater computational efficiency, compared with the original method.

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 Security of Supply in Gas and Hybrid Energy Networks

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 792
Author(s):  
Ruud van der Linden ◽  
Ryvo Octaviano ◽  
Huib Blokland ◽  
Tom Busking
Keyword(s):  
Supply And Demand ◽  
Distribution Networks ◽  
Stochastic Method ◽  
Hybrid Network ◽  
Gas Distribution ◽  
Security Of Supply ◽  
Real Gas ◽  
Hybrid Energy ◽  
Gas Network ◽  
Energy Networks

Reliable energy supply becomes increasingly complex in hybrid energy networks, due to increasing amounts of renewable electricity and more dynamic demand. Accurate modeling of integrated electricity and gas distribution networks is required to quantify operational bottlenecks in these networks and to increase security of supply. In this paper, we propose a hybrid network solver to model integrated electricity and gas distribution networks. A stochastic method is proposed to calculate the security of supply throughout the networks, taking into account the likelihood of events, operational constraints and dynamic supply and demand. The stochastic method is evaluated on a real gas network case study. The calculated security of supply parameters provide insight into the most critical parts of the network and can be used for future network planning. The capabilities of the coupled hybrid energy network simulation are demonstrated on the real gas network coupled to a simplified electricity network. Results demonstrate how combined simulation of electricity and gas networks facilitate the control design and performance evaluation of regional hybrid energy networks.

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