|Optimization of Incompressible Network Piping Systems
Mercury does what no human and no other incompressible flow software can do: run millions of scenarios to optimize a piping system for cost, energy consumption, weight or size.
AFT Mercury is built on and includes all of the modeling building tools and analysis capabilities of AFT Fathom. Models of incompressible piping systems may be developed and analyzed within AFT Mercury as in AFT Fathom, or model files developed within AFT Fathom may be opened by AFT Mercury. Please refer to to AFT Fathom pages for a description of of these capabilities.
In addition to these powerful analysis and modeling simulation capabilities, AFT Mercury employs an advanced optimization engine developed by Vanderplaats Research & Development to automatically determine optimal pipe and equipment sizes.
Selected through Optimization Control, AFT Mercury 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 Mercury conduct a continuous or discrete optimization. In a continuous optimization, AFT Mercury will identify the optimal pipe diameters on a continuous basis, that is, as if any diameter were available. When discrete optimization is selected, AFT Mercury 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 Mercury that make it unique as the first optimization tool for real world systems.
|In addition to the optimization engine, AFT Mercury includes several unique interface features necessary for optimization, as described below.
Size Ranges (Discrete optimization)
When AFT Mercury searches for an optimal system, it does so by evaluating different pipe size combinations. The user tells AFT Mercury 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 Mercury or may come from a new pipe database input 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 basid 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 Mercury 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. Linking thus 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 Mercury. Approximately 60 different constraints are available, including - Pipe constraints - velocity, flow rate, pressure, pressure gradient Pump constraints - NPSHR margin to NPSHA, BEP (best efficiency point) proximity, head, pressure rise, speed, power 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 Mercury model may use any number of constraints. Any number or combination of requirements may be specified in the optimization of a system.
|Optimization over Multiple Cases
|Many, if not most, systems have multiple operating requirements. A ducting system that operates with both fans in the summer but only one in the winter, or a water supply system that must provide a minimum flow and pressure to the system demands during normal operation while also meeting minimum supply requirements to hydrants during fire suppression. With AFT Mercury you may make any number of alternate cases of your system model, with each using its specific constraints. Optimization of the system is thus obtained while considering the requirements for each of the differing cases.
|As with AFT Fathom, AFT Mercury includes engineering databases for piping materials, components (pumps, valves, etc.), fluids and insulation. The standard material database contains information for the following pipe materials:
Additional pipe materials may be easily added to the database by the user.
- IPS size steel
- IPS size stainless steel
- Ductile iron
- Copper tubing
- Copper pipe
- Rectangular ducting
- Round ducting
Any component defined within AFT Mercury 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; pump, valves, control valves, heat exchangers, etc.
In addition to these engineering databases, AFT Mercury 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 hydraulic characteristics of a pump and included them in the component database, but have not yet settled on whether it will be cast iron/bronze fitted or of fully bronze construction. One can easily conduct an optimization with either by simply changing the pump cost database used.
AFT Mercury'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.
|AFT Mercury includes the same rich output combination of text based and graphical output of AFT Fathom and, in addition, output related specifically to system optimization.
Cost report provides a detailed listing of all costs by item, along with summaries by cost group (piping, pumps, etc) and type (materials, installation, operation, etc).
The piping section optimization tab displays the optimized by sizes, while Scenario Manager allows you to create an optimized scenario with these pipe sizes.
Active constraints for pipes and junctions are displayed, clearly indicating what's driving your design. While any number of constraints may have been included in the optimization, only some will be limiting how low a cost may be obtained. Perhaps a velocity constraint has been included and is active. If so, allowing a higher velocity will permit a reduction in system cost. Is the higher velocity worth the cost reduction? This is easily tested with AFT Mercury by changing the constraint value and re-running the optimization.
|Windows 95 and higher or NT 4.0 and higher
32 MB RAM minimum
800x600 display minimum
5 MB hard disk space
Stand-alone or network