Heat-transfer options

Figure 3.58 Selecting Constant temperature, Heat transfer option.

Results with Several Heat Transfer Options... 

The results above are for the constant medium temperature heat transfer option. Effective temperature control is obtained. In this section we want to compare these results with... 

Figure 3.95 Selecting the LMTD heat transfer option.

LMTD Figure 3.95 shows the parameters that must be specified when this heat transfer option is selected. The inlet temperature of the cooing water is set at 294 K. The temperature approach is set at 10 K. This means that the cooling water leaves the system at a... 

Note that this controller gain is higher than that found for the constant-temperature heat transfer option. 

Figure 3.99 Selecting the Dynamic heat transfer option.

Figure 3.103 Comparison of CSTR heat transfer options reactor temperatures.

However, there are other options for setting up the condenser, which can be used to obtain more realistic models. Figure 8.21 shows that cUcking the drop-down arrow on the right of the Heat transfer option gives several options. The Constant duty option is the default and produces a dynamic model in which condenser heat removal is the manipulated variable. 

The normal distillation models assume instantaneous heat transfer in the condenser and reboiler, and the normal default heat-transfer option is Direct Q. The basic model does not accurately represent the short-term rapid dynamic response under sevCTe conditions because the capacitance (holdup) of material and mass of equipment metal in the reboiler and condenser heat exchangers are not considered. 

On a heat transfer option for moisture analysis by KF, the sample is heated at a temperature greater than 100°C in an attached oven for a specified amount of time under a flow of dry nitrogen. The water evolved is carried by the flowing gas and concentrated by bubbling into the Karl Fischer titration vessel containing methanol. Karl Fischer reagent is used, and water reacts with the titrant as indicated above. 

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