Pipe Heat Transfer
This window is used to supply heat transfer data for the pipe unit. By default PRO/II does not consider heat transfer (i.e. sets duty to be zero) during calculations. You may specify the heat to be added uniformly to the pipe over its length (representing a furnace) or lost to the ambient surroundings, allowing the fluid to cool as it flows down the pipe.
Usage
To display this window, push the Heat Transfer button from the Pipe Main Window.
Duty Calculation Options
PRO/II allows you to specify the heat transfer in three different ways. They are:
1. Fixed Duty : This option represents external heat transfer into or out of the pipe unit in millions of energy units per time unit. A positive value indicates heat input, while a negative value signifies cooling. The default value is zero (no heat transfer).
Note that heat input to a backward calculation is the same as heat removal from a normal, forward calculation. If you have divided the pipe into segments for the pressure drop calculations, then the duty is equally divided among each of the segments.
2. Ambient Heat Transfer : You may specify the Overall U (heat transfer coefficient, based on the inside diameter) and the outside Ambient Temperature to calculate the heat transfer. PRO/II uses these values along with other pipe data including pipe inlet and outlet temperatures, inside area, etc. to compute the heat transfer.
3. Isothermal Operation : This option forces the outlet temperature to be the same as the inlet temperature and automatically calculates the required duty to achieve this.
For the fixed duty and overall U parameters, instead of entering a numeric value they may be referenced using the Define system relative to any available unit operation or stream parameter calculated elsewhere in the simulation.
Note : When backward calculations are performed, the ambient heat transfer and isothermal options are not available.
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