The Cost Report is displayed in the General Results section of the Output window. View the Cost report by selecting the Cost Report Tab.
window. Figure 9.10 shows the Cost Report for this example with the Material, Installation, Operation/Energy, and Total costs displayed.
The Cost Report shows the total system cost, as well as the individual totals for the material, installation, and energy costs. In addition, the Cost Report displays the detailed cost for each pipe, junction, and fitting that was included in the report. The items are grouped together by type, and a subtotal for each category is listed.
Figure 9.10 The Cost Report in the General Output section shows the results of the cost analysis.
Analysis summary
The CST analysis for this example shows the following costs for the plant cooling system design:
Total System Cost: $2,920,461 Total Material Cost: $418,844 Total Installation Cost: $699,341 Total Operation/Energy Cost: $1,802,276 Cost of Pipe: $918,940 Cost of Pumps: $1,966,276 Cost of Fittings: $35,244
Cost optimization with AFT Mercury™
AFT Mercury is a tool built on AFT Fathom technology. With AFT Mercury you can automatically size all pipes or ducts in your system to minimize monetary cost, weight, volume, or surface area. In addition, you can concurrently size the pumps and pipes to obtain the absolute lowest cost system that satisfies your design requirements. Finally, by accounting for non-recurring and recurring costs, you can optimize pipe and duct systems to minimize life cycle costs over some specified duration.
By using AFT Mercury on this example, not only could the system cost be determined, but also the optimal system design could be determined.
C H A P T E R 1 0
Using Modules Together
Previous chapters have illustrated how to use each of the AFT Fathom modules by themselves. However, AFT Fathom also allows you to use the modules together, in any combination you choose. This allows even greater flexibility in the types of analyses that can be accomplished using AFT Fathom.
This chapter shows how the GSC, XTS, and CST modules can be used simultaneously by examining an example problem.
Note: This example can only be run if you have licenses for the CST, GSC and XTS modules.
Model file
This example uses the following file, which is installed in the Examples folder as part of the AFT Fathom installation:
• Fixed Head Supply Tank.fth – AFT Fathom model file
Problem statement
A process plant requires the delivery of water at a fixed head, regardless of the system demand. This is accomplished by pumping the water to a supply reservoir, and maintaining a constant fill-level by varying the supply pump speed as the process demands change. Throughout any
24-hour period the process demands vary from as little as 500 gal/min to peak demands of 2500 gal/min.
Use the GSC and XTS modules to analyze the system performance over a 24-hour period. Use the CST module to determine to energy costs for the pump with this daily operation over one year.
Start AFT Fathom
From the Start menu, choose AFT Products and AFT Fathom.
Open the model file
Open the Fixed Head Supply Tank.fth model file, which is located in the Examples folder in the AFT Fathom application folder. Save the file to a different folder.
The model should appear as shown in Figure 10.1.
Variable and goal settings
The GSC module is used to keep the level of the fluid in the Process Supply Tank constant by varying the pump speed. Open the Goal Seek and Control Manager and view the variables and goals (see Figure 10.2).
The variable for this problem is the pump speed. The goal is defined as a point goal on the Process Supply Tank junction. The desired goal is for the net volumetric flow rate into the junction to be zero, which will keep the water level in the tank constant.
Transient control settings
The XTS module is used to model the process demand changes over the 24-hour analysis period. Open the Transient Control window to view the Transient Control settings (see Figure 10.3). The transient analysis is set to run for a period of 24-hours with a time step of 10 minutes.
Figure 10.1 Model of a Fixed Head Supply Tank (model file from the Examples folder in the AFT Fathom folder).
Figure 10.2 Goal Seek and Control variable and goal settings.
Figure 10.3 Transient Control settings for a 24-hour period.
Junction transient data
The flow variation in this model is driven by the J4 Assigned Flow junction. Open the J4 Assigned Flow Specifications window and select the Transient tab. The process flow demands are modeled as time-varying flows. The flow profile over the 24-hour period is defined in the Transient Data table (Figure 10.4).
In addition, the J3 Reservoir junction is modeled as a finite reservoir (Figure 10.5). The J3 Reservoir can potentially drain and fill, and the varying pump speed (and, hence, flow) is what will keep its liquid level at 15 feet.
Figure 10.4 Flow demand over 24 hours at the J4 junction.
Figure 10.5 J3 Reservoir junction is finite, which means it can drain and fill.
Cost settings
For this problem, the pump energy cost for the 24-hour analysis period is entered as a fixed energy cost on the Cost Settings window. Open the Cost Settings window from the Analysis menu to view the energy cost settings (Figure 10.6).
The Cost Time Period for the cost analysis is set to one year. The 24-hour operation is assumed to repeat every day for this one-year period, and the total energy cost will be calculated assuming the 24-hour operation repeats non-stop throughout the year. More complicated cost variation is possible when using energy cost databases.
Note that the cost calculation display is selected in the Cost Settings window by selecting the Calculate Costs option.
Run the model
Select Run Model in the Analysis menu. This will open the Solution Progress window. This window allows you to watch as the AFT Fathom
After the run has completed, the results can be reviewed by clicking the View Output button.
Figure 10.6 Cost Settings window applies Operation/Energy cost, can set the energy cost, and specifies the cost time period.
GSC and XTS module solutions
When the GSC and XTS modules are used simultaneously, the GSC module is rerun for each time step. The GSC module variables are recalculated for the system conditions at each time step to ensure the specified goals are always met. This will typically result in longer run times, due to the increase in solution iterations that must be solved for each time step analysis.
Examine the results
When using multiple modules, the goal seek, transient and cost analysis results are shown in the Output window in the same manner as when they are used individually.
The GSC variable and goal results in the General Output section can be viewed for each time step by using the slider bar at the bottom of the Output window, as shown in Figure 10.7.
GSC module goal results for Time = 0 hours
GSC module goal results for Time = 12 hours
Figure 10.7 The slider bar at the bottom of the Output window can be used to view the transient results at any time step, including the GSC module variable and goal results.
Cost data is displayed in the Cost Report in the General Output section, as shown in Figure 10.8. The one-year energy cost for the supply pump in this example was $42,129.
Figure 10.8 The cost data is shown in the Cost Report in the General Output section of the Output window.
Figure 10.9 shows how the GSC module varied the pump’s speed over time with the varying process flow rate. Figure 10.10 shows that the water level in the process supply tank remains constant over time (which
was the goal). The pump speed changes to increase and decrease the flow in order to keep the net flow into the Supply Tank zero.
Summary
Individually, the AFT Fathom modules provide you with powerful analytical tools to assist you in the design of your pipe systems. The ability to combine the capabilities of these tools provides you with even greater and more powerful modeling capabilities.
Figure 10.9 The GSC module varies the supply pump speed as the process flow rate changes over time (top).
Figure 10.10 The water level in the process supply tank remains constant over time due to the variation in the pump speed.
Glossary
cost database A database of pipe system component costs associated with an engineering database. The CST module obtains cost data for system components from cost databases and displays the costs in the Cost Report.
Cost Report The table shown in the Output window relating the total cost and individual costs for all items for the pipe system.
CST module An optional add-on module to AFT Fathom which allows users to calculate non-recurring and recurring cost for the pipe system design.
cyclic dual event A junction transient which has two initiation criteria which switch behavior from one transient state to the other and back Database Manager The window that allows creation and connection to network databases.
Energy/operational cost A recurring cost that represents the cost of operating a pump.
energy cost database A database of energy costs that can be used with pumps.
engineering database A database which has engineering data for pipe system components such as pipe diameters and pump curves.
event transient A transient which is initiated based on some criteria being satisfied in the system
finite reservoir A body of fluid which is small enough that its surface level changes significantly during the time frame of the simulation as a result of liquid inflow or outflow. An example is a tank which drains as the simulation progresses.
finite tanks See finite reservoir Goal See GSC goal
Graph Results window The graphical window that allows preparation of plots.
GSC goal Goals are the specified conditions that AFT Fathom will satisfy by changing the defined variables. Goals may be added,
duplicated, and deleted from the Goals tab on the Goal Seek and Control Manager window.
GSC module An optional add-on module to AFT Fathom which allows users to perform multi-variable goal seeking and simulate system control functions.
GSC variable Variables are the parameters that AFT Fathom will automatically vary in order to achieve the desired goals. Variables may be added, duplicated, and deleted from the Variables tab on the Goal Seek and Control Manager window.
Hydraulic Solver See Solver
infinite reservoirs A massive body of fluid whose surface level does not change appreciably as a result of liquid inflow or outflow during the time frame of the simulation. An example is a large lake or the ocean.
installation cost A non-recurring cost that represents the cost of installing a component.
junction In AFT Fathom, a pressure/head solution point that connects and balances flow from pipes.
maintenance cost A recurring cost that represents the cost of maintaining a component.
material cost A non-recurring cost that represents the cost of purchasing a component.
maximum cost group A group of pumps or control valves which are in the sizing stage but will eventually all be of the same design. The cost for each pump/control valve will therefore be the same. The maximum cost group looks for the most expensive pump/control valve in the group and uses that cost for all pumps/control valves in the group.
Model Data window The text-based window where the input for the model is given in text form and input data can be entered.
object A pipe system component (either a pipe or a junction) that is created, exists, and can be viewed on the Workspace.
object status The state of the object, whether defined or undefined.
operational cost See Energy/operational cost
Output window The text-based window that shows the results of the analysis.
pipe In AFT Fathom, a conduit for incompressible, steady-state fluid flow. All pipes have constant diameter and are completely filled with fluid.
Primary window One of AFT Fathom's two input or three output windows.
Quick Graph When using the XTS module, a feature in the Output window (activated with a right-click) which shows a graph of transient table contents
relaxation A parameter that affects how the iterative solution scheme approaches a pipe flow solution.
scenario A variant case of a model that is created in the Scenario Manager.
Scenario Manager Window that allows one to create and manage multiple pipe flow model scenarios. These include different equipment, sizes, and operating conditions.
sequential dual event A junction transient which has two initiation criteria. The first criteria will initiate a transient and the second, which will not occur until the first has occurred, will initiate a second transient.
The two transients will not cycle (see cyclic dual event) but will cascade from the first to the second and then will cease
Solver The part of AFT Fathom that contains the pipe flow network solution method.
Specifications window The window in which an object's properties are entered.
steady-state The condition of a system in which the rate of change of all parameters is negligibly small.
time transient A transient which is initiated absolute time in the transient solution
tolerance The value at which the Solver should consider that convergence has been obtained.
Variable See GSC variable
Visual Report window The graphical window that allows integration of the analysis results with the pipe system schematic.
Workspace The area of the Workspace window where models are visually assembled.
Workspace window The graphical window where model assembly occurs and input data can be entered.
XTS module An optional add-on module to AFT Fathom which allows users to simulate system transient behavior.
Index
qualifications for use 3 using online help 4 Animation 104
C
Central difference method 64, 68 Check Valve junction
inherent event logic 86 Control Valve junction
maximum cost groups 141, 146 Cost Application Manager 132 Cost Database window 114, 155 Cost Databases
Additional Loss costs 122 Creating 116, 155, 163
Repetitive costs 126 Scale tables 123, 159 Using 125
Cost Report 127, 145 in Output window 166 Cost Settings window 153, 174
Specifying cost categories 133 Cost Summary window 135
Database Manager 116, 117, 127, 132, 139, 164
Cost Databases 125 global multipliers 124
setting default database locations 134
Database Sources of cost data 127 Databases
Cost 113, 155, 163
Energy Cost database 142, 154 Engineering 113
Differential Goal 20
E
Energy Cost Database 142, 154 Engineering parameter optimization
144
Event messages 89 in Output window 109 Event transients 82
at a pump 99
Event messages in Output window 109
Example models 4
F
FathomExamples.hlp 4, 33, 91, 151 Finite reservoirs 54
Flow Volume calculations 144 Forward difference method 64, 67
G
General Preferences Database locations 134
Goal Seek and Control 43, See GSC module
Enabling on Analysis menu 43 Goals 39
Variable and goal results in Output window 44
Variables 38
Goal Seek and Control Manager 10, 23, 38, 42, 43, 170, 180
Goals 16, 40
numerical control 27, 28, 29 scenario differences 32 Variables 11, 38 View menu 10
Goals See Goal Seek and Control Manager
Differential Goal 20 Group Goal 20
cross-plotting profile graphs 73 group goal types 16
group goals 20
Group Max/Min goal example 40 maximum cost group 141, 146 GSC module 2
activating 4
setting up goal seeking 34
I
Ignore Transient Data See Transient Special Conditions
Infinite reservoirs 54
J
Junction Specifications window Cost data 131
Including costs data 165
opening in Goal Seek and Control Manager 15, 21
repeat transient 87 transient data 52
transient data - absolute vs. relative 87
Junctions
assigned flow 172 assigned pressure 95 branch 96
how multipliers are applied 148 Model Data window
GSC data 22, 42
transient junction data 61, 90 Monetary costs 143
N
Non-monetary costs 143
O
Output Control window 44
Cost Report formatting 145, 146, 167
time formatting and units 69, 96 transient pipe and junction data 69 Output window
changing time formats and units 96 Cost Report 127, 145, 166
Database Sources 127 Event messages 89
Parameter and Unit Preferences window Custom monetary units 144
Monetary units and currency conversion 144
Pipe and Fluid Weight calculations 144
Pipe Fittings & Losses Cost data 130
Pipe Inner Surface Area calculations 144
Pipe Specifications window Including cost data 165
opening in Goal Seek and Control Manager 21
Pipe Costs 127
Pipe Weight calculations 144 Point Goal 20
Pump junction
maximum cost groups 141, 146 Pump Specifications window
Turning pumps on and off during transients 99
Pump Transient summary report 102 Pumps
modeling transients 99
Q
Modeling finite tanks during transients 94
Reservoirs drained 60 finite 54 infinite 54
Maximum and minimum pressures in closed tanks 61
overflow 59
pipe depth and elevation input 61 Run Model 43, 101, 166, 174
S
Scale tables 123, 159
sequential dual events 84, See Event Transients
Show Object Status 37, 96 single event transients 82 Special Conditions 77
Transient 80
System Properties window 34, 92
T
Time-based transients 81
Transient Control window 50, 51, 81, 97, 170