|Optimization of Compressible Network Piping Systems
Titan does what no human and no other compressible flow software can do: run millions of scenarios to optimize a piping system for cost, energy consumption, weight or size.
|AFT Titan is built on and includes all of the modeling building tools and analysis capabilities of AFT Arrow. Models of compressible piping systems may be developed and analyzed within AFT Titan as in AFT Arrow. Model files developed within either AFT Arrow or AFT Titan may be opened by the other application. Please refer to tthe AFT Arrow pages for a description of of these modeling capabilities.
In addition to these powerful analysis and modeling simulation capabilities, AFT Arrow employs IntelliFlow® determine optimal pipe and equipment sizes that will meet system performance requirements at minimum cost.
What is IntelliFlow®? IntelliFlow® combines powerful network pipe flow analysis algorithms with state-of-the-art numerical optimization algorithms to intelligently evaluatethe complex interaction of system design variables. The system design is repeatedly perturbed and re-analyzed to define the shape of the design space, revealing combinations of design parameters that minimize cost. Design constraints specified by the engineer direct the search in areas that satisfy design requirements such as pressure, velocity and compressor pressure rise. Searching continues until an optimum design is found, which is then presented to the user.
Selected through Optimization Control, AFT Titan will perform either and Engineering Optimization or a Cost Optimization.
Engineering optimizations will determine optimal pipe sizes to minimize one of the following as selected by the user:
- Pipe weight
- Pipe plus fluid weight
- Pipe volume
- Pipe surface area
Cost optimizations will determine optimal pipe and component sizes to minimize:
- Initial, or non-recurring costs (materials, installation), or
- Life cycle cost, the sum of non-recurring and recurring costs (energy, maintenance)
Whether an Engineering or Cost optimization is performed, the user may elect to have AFT Titan conduct a continuous or discrete optimization. In a continuous optimization, AFT Titan will identify the optimal pipe diameters on a continuous basis, that is, as if any diameter were available. When discrete optimization is selected, AFT Titan will first conduct a continuous optimization, identifying the optimial inner diameters of the piping, and then proceed to identify the discrete optimum inner diameters from the list of available sizes; e.g. IPS nominal pipe sizes. Discrete optimization is significantly more difficult to determine than continuous optimization and is an example of the advanced capabilities of AFT Titan that make it unique as the first optimization tool for real world compressible flow systems.
|In addition to the optimization engine, AFT Titan includes several unique interface features necessary for optimization, as described below.
Size Ranges (Discrete optimization)
When AFT Titan searches for an optimal system, it does so by evaluating different pipe size combinations. The user tells AFT Titan which sizes to consider through pipe size range sets. Any number of size range sets may be defined and a size range set may include any or all of the pipes of a material type. These may be selected from any of the several standard pipe databases included with AFT Titan or may include new pipe data added to the database by the user.
Size range sets provide both control and flexibility in optimizing your system. For example, you want to use standard steel piping but exclude 3-1/2" and 5" which, while part of the IPS sizing, are not commonly available. Or you may want to limit the maximum height of ducting considered based on clearances available. This is readily done by including in the size range set only those sizes meeting your criteria. Since any pipe in the system may be associated with any size range set and any number of range sets may be included in the model, one can readily optimize a system that contains mixtures of pipe materials, schedules and size ranges.
|Just as practical optimization will usually consider a select set of pipe sizes, there are a variety of reasons why some pipes should be grouped into a common size. For example, while a supply main with many branches may theoretically have many size reductions as flow is decreased along its length, in practise we know that a more limited number of sizes along the supply main is desireable to reduce the number of pipe sizes to be ordered and handled and to avoid excess reducer fitting costs. Too, there will be instances where it is obvious that two or more pipes should be the same size, such as the supply and return lines to a heat exchanger which are carrying the same flow and have the same length and similar configuration.
In AFT Titan pipes may be linked to a reference pipe, referred to as a link basis pipe, which will keep all such linked pipes the same size as the reference pipe. There may be any number of link basis pipes and, thus, any number of linked pipe groups. Linking provides the user control to maintain a consistency in pipe sizes where desired.
|Constraints are the primary means by which you communique your design requirements to AFT Titan. Approximately 60 different constraints are available, including - Pipe constraints - velocity, flow rate, pressure, pressure gradient Compressor/Fan constraints - Flow, pressure rise, power, BEP (best efficiency point) proximity, speed Control valve constraint - pressure drop, Open percentage And others.
Constraints are defined within a constraint set, which may include any number of constraints. Also, an AFT Titan model may use any number of constraints. Any number or combination of requirements may be specified in the sizing of a system.
|Optimization over Multiple Cases
|Most systems have multiple operating requirements. A turbine supply steam system operating with one or two steam generators or a chemical feed system with varying load profiles over time. With AFT Titan you may make any number of alternate cases of your system model, with each using its specific constraints. Alternate cases can represent different system line ups and/or time varying demands. Optimization of the system is thus obtained while considering the requirements for all of the operating cases.
|As with AFT Arrow, AFT Titan includes engineering databases for piping materials, components (compressor/fans, valves, etc.), fluids and insulation. The standard material database contains information for the following pipe materials:
Additional pipe materials and types may be easily added to the database by the user and databases may be shared across a network. AFT Titan directly models rectangular ducting as well as cylindrical so that ducting for ventilation or other low pressure systems may be readily modeled.
- IPS size steel
- IPS size stainless steel
- Ductile iron
- Copper tubing
- Copper pipe
Any component defined within AFT Titan may be added to the Component Database making it readily available to add to any system model. These can be virtually any type of piping system component; compressor, fan, valves, control valves, heat exchangers, etc.
In addition to these engineering databases, AFT Titan utilizes cost databases to use in conjunction with cost optimization. Each cost database is associated with an engineering database. Multiple cost databases may be associated with an engineering database, providing great flexibility in managing costs for item. For example, separate cost databases may be developed for black and galvanized steel pipe. Both can be associated to the steel pipe engineering database and then used in a specific optimization by simply connecting to the cost database desired. Or you may have defined the performance characteristics of a compressor and included them in the component database, but have not yet settled on whether it will be engine or motor driven. One can easily conduct an optimization with either by simply changing the cost database used.
AFT Titan's cost database manager lets you readily define and review costs for items. The definition of costs can be done in a variety of ways best suited to each item. Piping, for example, may have costs associated by unit length of weight. Pump and control valve costs may be define on a per unit basis or a per power or flow capacity basis. Other piping components such as valves and fittings, may have costs defined on a per unit or per diameter basis. In all cases, costs for both non-recurring (material, installation) and recurring (operation, maintenance) may be included. Indeed, any type of cost that may be characterized as either non-recurring or recurring may be included in the cost calculation and, therefore, the cost optimization. Additionally, recurring costs may be varied over time, for example, a per kw-hr rate varying over the system life span.
|A tabular display of calculated results, the Output window is organized into General, Pipes and Junctions sections, which can be displayed all at once or individually. Additionally, the General and Junctions sections have tabbed sub-sections to quickly view specific categories. For example, the General section provides tabbed summaries for compressor/fans, valves and heat exchangers, it present in the model. The Junctions section has tabs to view the output results of all junctions as well as a tab for each type of junction in the model.
The Output provides extensive control by the user for such items as; what objects and parameters are displayed, units, order (including sorting), as well format controls for viewing and printing, all of which may be changed and the revised output viewed without re-running your model.