A Fast, Highly Accurate Means of Modeling Transient Flow in Gas Pipeline Systems by Variational Methods

1974 ◽  
Vol 14 (02) ◽  
pp. 165-178 ◽  
Author(s):  
H.H. Rachford ◽  
Todd Dupont
Keyword(s):  
Transient Flow ◽  
Cost Effective ◽  
Central Processor ◽  
Processor Time ◽  
Pipe System ◽  
Pipeline Systems ◽  
Design For Cost ◽  
The Cost ◽  
Varying Demand ◽  
Effective Design

Abstract The cost-effective design of real pipeline systems must consider thetransient response induced by equipment failure and sales rate changes. Hereare described methods developed over the past decade for simulating slowtransient response; these are followed by a presentation of a new variationalmethod. The latter is formulated to treat fast as well as slow transients, andgives results in excellent agreement with data for diverse cases. The computer resources required are small enough that a 1,000-pipe networkcan be simulated in core on widely available computing facilities (CDC 6600).On the average, 1 hour of 1,000-pipe system operation can be simulated in 100seconds of CDC 6600 central processor time. Introduction To design and operate a gas transmission system cost-effectively requiresaccounting for its response under unsteady or transient conditions. Even thoughcare is given to the optimum design of a system to support steady loads, suchloads represent only a theoretical condition. Actua1 operations invariablyencounter transient states. The loss of a compressor, the addition or loss ofsupply or sale points, replacement of equipment, and customers who demandvariable sale rates are a few of the causes of line transients. The design for cost-effective operation of a system should be completed beforeany capital is spent. For pipeline systems this should begin with optimizingthe required facilities to meet the projected sales rates. But engineering isnecessary beyond that to provide the pipe and compression for steady deliveryof gas. If some of the projected sales are time varying, a quantitative studyshould be made of the fraction of the varying demand that can be met by linepack and the fraction that must be satisfied by local peaking facilities. Onlyby approaching the cost optimum among feasible pipe sizes, compression levels, and peaking facility capabilities can cost-effective use be made of availablecapital. Other facets of cost-effective design for operation are the sizing and locationof standby equipment, its relationship to the capacity of the transmissionsystems, and the cost of failure of the system to meet commitments. Anymechanical system is subject to failure. The allowable time for bringingstandby equipment on line so as to meet all commitments depends upon thecapacity of the standby equipment, the capacity and response rate of thetransmission system, and the amount and location of excess compression or othercapacities elsewhere in the system.

Price structures for electricity supply and potential consequences for building services systems

2021 ◽  
pp. 014362442199081
Author(s):  
Roger Hitchin
Keyword(s):  
Cost Effective ◽  
Building Design ◽  
Electricity Supply ◽  
Cooling Systems ◽  
Price Structure ◽  
Heating And Cooling ◽  
Future System ◽  
The Cost ◽  
Supply Systems ◽  
Effective Design

Policies to reduce carbon emissions are leading to substantial changes in the demand for electricity and to the structure of electricity supply systems, which will alter the cost structure of electricity supply. This can be expected to result in corresponding changes to the price structure faced by customers. This note is an initial exploration of how possible new price structures may impact on HVAC system and building design and use. Changes in the price structure of electricity supply (separately from changes in price levels) can significantly affect the cost-effective design and operation of building services systems; especially of heating and cooling systems. The nature and implications of these changes can have important implications for future system design and operation.

Evaluation of Numerical Methods Applied in the Analysis of the Transient Flow of Pipeline Systems

2012 ◽  
Author(s):  
Bruno F. Flora ◽  
Raphael I. Tsukada ◽  
Vinícius M. Rodrigues ◽  
José R. P. Mendes ◽  
Adriane S. B. Serapião
Keyword(s):  
Numerical Methods ◽  
System Design ◽  
Oil And Gas ◽  
Transient Flow ◽  
Water Hammer ◽  
Great Distance ◽  
Simple Problem ◽  
Pipeline System ◽  
Pipe System ◽  
Pipeline Systems

Brazilian subsea exploration is increasing specially after the post salt petroleum field discovery. Several challenges have been imposed for the production of those fields. In this scenery, the transport of oil and gas from the production field to the continent is a problem, especially when the fields are located at a great distance from the coast. A possible solution could be the use of subsea pipeline systems, for the transportation of the fluids produced from the petroleum wells. For the pipeline system design it is highly recommended the evaluation of the transient flow, considering the water hammer phenomenon. The definition for this phenomenon is given by the pressure variation due to operation singularities in the pipe system. The disruption in the flow originated by the operation of valves or failure of a pump can be listed as some of the main causes of the water hammer. The basic equations to model the water hammer in fluid mechanics comes from two partial differential equations, the equation of continuity and momentum. The solution of those equations can be obtained by different numerical methods. In this context, this work seeks to contrast results obtained by finite difference method (FDM), the method of characteristics (MOC) and finite elements method (FEM) solutions for the water hammer problem. Those numerical methods were implemented and used to solve a simple system, which are composed of an infinite reservoir, a pipeline and a valve. In this case the valve is closed, originating the water hammer phenomenon. Although it can be considered a simple problem, it allows the evaluation of those numerical methods. Performance, convergence and accuracy were evaluated in order to support the choice of the best numerical method for the development of a numerical simulator used in complex and greater pipeline system design.

scholarly journals The infrastructure cost planning model : an integrated solution to cost effective design

2009 ◽  
Author(s):  
◽  
Shian Hemraj Saroop
Keyword(s):  
Planning Process ◽  
Cost Effective ◽  
Design Stage ◽  
Planning Model ◽  
Infrastructure Projects ◽  
Cost Planning ◽  
Design Options ◽  
The Cost ◽  
Cost Report ◽  
Effective Design

Infrastructure project costs are being scrutinised more closely and with greater skill and accuracy as projects have become larger, more complex and more expensive, and clients have become more exacting in their requirements. These and other factors compel engineers to design with greater care and in more detail. However, public planners spend very little time generating alternative project options, often presenting decision-makers with only a few poorly differentiated alternatives borrowed ad hoc from other projects. Even more disturbing is that they often devote the greatest amount of decision making resources to the development of a single decision rather than a variety of options. A systematic and iterative analysis of the cost consequences of different design solutions is commonly suggested for infrastructure projects, but rarely happens. There is a growing need to integrate design and costs. This study concentrates on the issue of cost optimisation of infrastructure projects (particularly at the design stage of the project) and applies construction economics, cost planning, cost optimisation and value engineering techniques to the design of such projects. The methodology proposed in this study for the optimisation of cost and design planning is the Infrastructure Cost Planning Model. This model divides the planning of a project into four stages and utilises twelve Cost Report Forms across these stages. The Cost Report Forms define in a comprehensive, precise and verifiable manner the essential characteristics of a deliverable component. They are used to measure, quantify, verify and audit the different design options. By means of the Cost Report Forms, the Infrastructure Cost Planning Model enables the client to select a combination of alternatives and evaluate a number of possible design options – with their cost implications – at each stage of the design process. This i promotes transparency and accountability, and enables consultants and clients to have greater control over the planning process and overall costs. Two case studies on infrastructure related projects were conducted and confirm that the Infrastructure Cost Planning Model can reduce costs. This study demonstrates that it is possible to overcome the problem of over expenditure by introducing cost effective design decisions prior to the infrastructure design approval process. The Infrastructure Cost Planning Model can improve infrastructure standards and procure design in a cost effective, equitable, competitive and transparent manner. This study contributes to the underdeveloped area of cost planning and forecasting of infrastructure projects. The findings are relevant to the South African government's infrastructure service delivery programme and the general issue of affordable infrastructure services.

scholarly journals Balancing the books – a statistical theory of prospective budgets in Earth System science

2003 ◽  
Vol 7 (3) ◽  
pp. 257-267
Author(s):  
J. P. O'Kane
Keyword(s):  
Sampling Error ◽  
Hypothesis Test ◽  
Cost Effective ◽  
Mathematical Function ◽  
Earth System ◽  
Space Filling ◽  
Definition Of ◽  
The Cost ◽  
Effective Design ◽  
Types Of Error

Abstract. An honest declaration of the error in a mass, momentum or energy balance, ε, simply raises the question of its acceptability: "At what value of ε is the attempted balance to be rejected?" Answering this question requires a reference quantity against which to compare ε. This quantity must be a mathematical function of all the data used in making the balance. To deliver this function, a theory grounded in a workable definition of acceptability is essential. A distinction must be drawn between a retrospective balance and a prospective budget in relation to any natural space-filling body. Balances look to the past; budgets look to the future. The theory is built on the application of classical sampling theory to the measurement and closure of a prospective budget. It satisfies R.A. Fisher's "vital requirement that the actual and physical conduct of experiments should govern the statistical procedure of their interpretation". It provides a test, which rejects, or fails to reject, the hypothesis that the closing error on the budget, when realised, was due to sampling error only. By increasing the number of measurements, the discrimination of the test can be improved, controlling both the precision and accuracy of the budget and its components. The cost-effective design of such measurement campaigns is discussed briefly. This analysis may also show when campaigns to close a budget on a particular space-filling body are not worth the effort for either scientific or economic reasons. Other approaches, such as those based on stochastic processes, lack this finality, because they fail to distinguish between different types of error in the mismatch between a set of realisations of the process and the measured data. Keywords: balance, budget, sampling, hypothesis test, closing error, Earth System

scholarly journals The Regulatory Choice of Noncompliance in the Lab: Effect on Quantities, Prices, and Implications for the Design of a Cost-Effective Policy

2016 ◽  
Vol 16 (2) ◽  
pp. 727-753 ◽  
Author(s):  
Marcelo Caffera ◽  
Carlos Chávez
Keyword(s):  
Laboratory Experiments ◽  
Market Price ◽  
Cost Effective ◽  
Theoretical Models ◽  
Tradable Permits ◽  
Effective Policy ◽  
The Cost ◽  
Effective Design ◽  
Compliance Versus ◽  
Theoretical Developments

Abstract Recent theoretical developments show the conditions under which it is cost-effective for the regulator to induce perfect compliance in cap-and-trade programs. These conditions are based on the ability that a regulator with perfect information has to induce the firms to emit any desired level with different combinations of the number of permits supplied to the market and the monitoring probability, assuming that firms are expected profit maximizers. In this paper, we test this hypothesis with a series of laboratory experiments. Our results suggest that firms may behave significantly different from what these models predict precisely when the different combinations of the supply of permits and the monitoring probability induce compliance versus noncompliance. More specifically, by allowing noncompliance in a manner consistent with theory, the regulator could produce a decrease in emissions and an increase in the market price of tradable permits that is not predicted by the theoretical models. The implications for the cost-effective design of environmental policy are discussed.

scholarly journals Application of the D3H2 Methodology for the Cost-Effective Design of Dependable Systems

Safety ◽  
2016 ◽  
Vol 2 (2) ◽  
pp. 9 ◽  
Author(s):  
Jose Aizpurua ◽  
Eñaut Muxika ◽  
Yiannis Papadopoulos ◽  
Ferdinando Chiacchio ◽  
Gabriele Manno
Keyword(s):  
Cost Effective ◽  
Dependable Systems ◽  
The Cost ◽  
Effective Design

scholarly journals Design Approach for Sub-surface Flow Constructed Wetlands

2012 ◽  
Vol 10 ◽  
pp. 42-47
Author(s):  
Anish Ghimire ◽  
Ajay Kumar KC ◽  
Bijay Thapa
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Cost Effective ◽  
Surface Flow ◽  
Design Approach ◽  
Design Parameters ◽  
The Cost ◽  
Physical And Chemical ◽  
Effective Design ◽  
Surface Flow Constructed Wetlands

Constructed Wetlands are an engineered wastewater treatment system that tries to mimic the natural biological, physical and chemical processes to treat wastewater. It is emerging as a cost-effective decentralized wastewater treatment solution in the communities where there is availability of inexpensive lands and lack of skilled operators. Different design approaches have been followed and design parameters based on different literatures have been chosen to design a Sub-surface Flow Constructed Wetlands. A simplified design approach well suited to climatic needs to be developed to maintain the cost effectiveness of the system. The kinetic parameters involved in the treatment should be selected properly in order to get the effective design of the system.DOI: http://dx.doi.org/10.3126/hn.v10i0.7102 Hydro Nepal Vol.10 January 2012 42-47

scholarly journals Cost Scaling Laws and Their Origin: Design Strategy for an Optical Array Telescope

1984 ◽  
Vol 79 ◽  
pp. 379-394 ◽  
Author(s):  
C.M. Humphries ◽  
V.C. Reddish ◽  
D.J. Walshaw
Keyword(s):  
Power Law ◽  
Scaling Laws ◽  
Cost Effective ◽  
Design Strategy ◽  
Cost Scaling ◽  
The Cost ◽  
Effective Design ◽  
Optical Telescopes

AbstractPower law relationships between cost and aperture of optical telescopes are shown to be approximations to polynomial expressions. These polynomials, which are derived for telescopes of traditional and cost-reduced design, have implications for the cost-effective design of an optical array telescope.

scholarly journals Conceptual Design of a Low - Cost Linear Actuator for Variable Span Wing Application

2021 ◽  
Vol 13 (1) ◽  
pp. 69-76
Author(s):  
Aynul HOSSAIN
Keyword(s):  
Conceptual Design ◽  
Low Cost ◽  
Cost Effective ◽  
Linear Actuator ◽  
Morphing Wing ◽  
Development Costs ◽  
Variable Span ◽  
The Cost ◽  
Effective Design ◽  
Selection Of

Aerospace actuators can be found throughout modern commercial and experimental aircraft, as well as in military and space exploration. The aerospace industry is not only growing, but also rapidly changing and the demand for aerospace actuators is permanently increasing. Linear actuator is able to push, pull, and hold objects in a way that our bodies cannot. Additionally, electrically powered technology provides more sophisticated control options. Linear actuator drive many different functions that are essential to safe and efficient aircraft operation. Manufacturers and hobbyists alike are always on the hunt for new ways to automate functions while keeping development costs low. Providing cost-effective linear solutions for aerospace application is one of the biggest challenge. This research will provide a cost-effective actuator conceptual design for variable span morphing wing UAV. The cost-effective design will be presented along with the application-based selection of linear actuators for morphing wing UAV.

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