Information Technology Reference
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12
5
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B2
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B4
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B1
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Figure 9.5 Process with two heat exchangers.
Figure 9.6 Tear streams for a process with heat exchangers.
9.2 HEATX BLOCK
The Heatx block has very wide applicability, as shown in its primary input form shown
in Figure 9.7. To use a Heatx exchanger in a simulation, it must have been designed so
that it can be used as part of the sequential modular approach. Note that Heatx permits
a design, a rating, and a simulation mode. The simulation mode requires that the inputs
to the exchanger be either specified or calculated from a previous block, because the
block is expected to behave as a sequential modular model. The rating mode permits
the specification of a block output as shown in Figure 9.8 and behaves as if it were a
sequential modular model with a design specification imposed on an output.
The simplest approach for using the block for design is to select a shortcut design,
in which case an output of an exchanger is specified. The available specifications for
design are shown in Figure 9.7. The solution to the design problem, using the shortcut
method, yields a value for the UA product which can be employed as part of the
specifications when setting up a simulation problem. An example of this approach
is given in the solution to the flowsheet shown in Figure 9.5, which incorporates
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