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Now it’s Super Easy! Changing Input Data in AFT Models using Excel Change Data

We've previously discussed how to make input data changes in AFT Models using the Excel Change Data feature on other blogs, but since we are continuously asked about expedited ways to input and change data, we've updated our feature to make things even easier. AFT Software has an abundance of features that make the model input process tremendously efficient: global pipe and junction editing, copying input data from other pipes and junctions, databases, and finally, importing data using the Excel Change Data  (which is the focus of this blog).

Excel Change Data, available in AFT Fathom 10, AFT Arrow 7, and AFT Impulse 7; is the feature we've created to import data from an Excel spreadsheet populated according to a specific format. AFT Software will automatically change pipe and junction input in your model to reflect the values specified in the spreadsheet. It is important to note that any fields with parameters you wish to change must already have some value specified, which is one of the misunderstandings that some of our users have faced while using the feature.

For example, if you wish to change pipe lengths in your model, there must be a value for those pipe lengths already (even if all pipe lengths are simply specified as 1 ft). The reason for this is that the Excel Change Data will not change the units of your pipe or junction input, but rather, it will only change the value in the model to the value specified in the spreadsheet. It is also important to note that there are other parameters that can be changed, and that any parameter the Excel Change Data directs AFT Software to change must already be specified in the model.

For example, let's say that you are modeling a heat exchanger with heat transfer, and the output temperature of the heat exchanger is fixed (this is specified by using a thermal model of "Controlled Downstream Temperature"). If properly specified in the Excel spreadsheet, Excel Change Data will change the defined heat exchanger outlet temperature, but it will not change any heat exchanger parameters not selected (such as any input related to the Secondary Fluid Data, since this input is deactivated when the heat exchanger is being modeled with a heat transfer model of "Controlled Downstream Temperature").

To demonstrate how to take advantage of the Excel Change Data functionality in AFT Software, let's walk through this AFT Fathom model (shown in Figure 1).


Figure 1: AFT Fathom model used for Excel Change Data

In this model, the heat exchanger Thermal Model is specified as a Controlled Downstream Temperature, and the heat exchangers are modeled using a K factor. The heat exchanger Thermal Data tab is shown in Figure 2.

Figure 2: Heat Exchanger Thermal Data tab with a Thermal Model specified as Controlled Downstream Temperature

We will use the Importing Excel Change Data feature in AFT Fathom to change the specified Controlled Output Temperature (initially modeled as 100 deg. F) to 300 deg. F, the specified K values for the valves from the initial K factor to a K factor that is 50% larger, and the pipe lengths and nominal sizes. Note that the heat exchanger must first be modeled with the desired Thermal Model, and that a controlled outlet temperature must be initially defined, since the Excel Change Data feature only changes existing input.

To import data from an Excel spreadsheet into AFT Fathom, AFT Arrow, and AFT Impulse, the Excel spreadsheet must be configured according to a specific format shown in Figure 3 with appropriate values in each column. The necessary input for each column is described below:

Column A: "Comment Column"- Any input in the comment column is not used by AFT software. It is most commonly used to describe the junction and parameter that the data in that row applies to.

Column B: "Apply Column"- This column signals that the row should be read by the AFT software. Inputting a "Yes" means that the data will be read, while an "No" means that the data will not be read. This column is helpful when you only want to change some model input using the Excel Change Data, but you do not want to have to delete some rows in the spreadsheet.

Column C: "Object Type"- Here you will have to select the type of object you are changing the input for; it varies, for example, from: pipe, pump, reservoir, among others.

Column D: "Object Number"- The object number is the pipe or junction ID number on the Workspace of the AFT software. In our example, the heat exchangers are junctions J3 and J4, so their Object IDs are 3 and 4, respectively.

Column E: "Parameter"- The parameter represents what parameter you are trying to change. For example, the pipe's length' or the heat exchanger's fixed temperature, among others.

Column F: "Change Code"- The change code specifies what type of change you would like to make to the parameter. There are three possible options under Change code, set equal to value, change by value (+/-), or change by percent (+/-). For example, if you want to change the pipe length from 10 ft to 50 ft, the change code should be "set equal to value".

Column G: "Value"- This is the column in which you specify what the input should be changed to.

Column H: "Scenario Path Name"- This column specifies the scenario in which the changes will be made, if the Scenario Path Name is blank, the changes will be applied to the current scenario.

Figure 3. Excel Change Data Spreadsheet format

This already formatted Excel Sheet can be found inside your AFT Software folder. Now that we know what parameters we want to change, we must create our Excel spreadsheet. Figure 4 shows our spreadsheet with the columns completed per the formatting requirements. Note that the Sheet name needs to be "AFT Transfer", though the spreadsheet name can be anything.

Figure 4. Excel Change Data Spreadsheet

Once the spreadsheet has been created and saved, you can import the data by clicking on File > Import Excel Change Data, then browse to the spreadsheet. Once the changes have been made from Excel, AFT Fathom, AFT Arrow, or AFT Impulse will provide an Object Change Log, which summarizes all changes that were made. If any errors occurred, these will also be displayed. Figure 5 shows the Object Change Log for this example.

Figure 5: Example Object Change Log

The Excel Change Data feature is an incredibly helpful tool that allows you to quickly change your model input. You will find this extremely helpful as models get larger and the amount of input data that has to be changed increases. This feature provides the user the flexibility to make changes on a wide variety of input parameters in an optimized way. Coupled with the global pipe and junction editing features, you can quickly define your model to get the answers you need.



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Thursday, 17 January 2019