Heat Exchanger Configuration
The stream flow pattern in a two-sided heat exchanger can be either Countercurrent or Cocurrent. The default configuration is countercurrent with 1 tube pass and 1 shell pass.
For countercurrent flows, the geometry can be specified either as the number of tube and shell passes or using an LMTD correction factor (FT). If the number of tube and shell passes are specified, PRO/II calculates the correction factor for N-2N exchangers. Therefore, if the number of passes is specified, the number of tube passes should always be twice the number of shell passes except when both the passes have a value of 1.
Cocurrent flow always assumes 1 tube pass and 1 shell pass.
Usage
From the Simple Heat Exchanger Main Window push the Configuration button to display this window.
1. Select the flow direction to be either Countercurrent (default) or Cocurrent.
2. If you have selected countercurrent flow, you may change the number of tube and shell passes or enter a LMTD correction factor.
If you enter a value for the number of shell passes, the number of tube passes is automatically reset to twice this value. Similarly, entering a value for the number of tube passes results in automatic resetting of shell passes to half this value. If 1 is entered for the number of tube passes, the shell passes is also set to 1. Entering an odd number other than 1 for tube passes will produce an error.
Instead of entering a numeric value for the correction factor (FT), it may be referenced using the Define system to any available unit operation or stream parameter calculated elsewhere in the simulation.
If the temperature crossover is detected, select Set unit to Not Solved, if temperature cross over detected to set the heat exchanger to Not Solved status.
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