Multi-Effect Evaporator: Equipment tab

Variable Definitions, Ranges and Default Values

The following table shows the meaning of the variables appearing in this tab, as well as their default values and their generally acceptable range. Note that due to the manner by which the variables are used by the sizing and costing equations, the range of acceptable values may be further reduced.

Variable	Default Value	Range

● Number of Effects Per Unit The number of evaporators that comprise a multi-effect evaporator unit. The default number of effects is equal to 1. Therefore, the default unit corresponds to a single evaporator. Additional effects may be specified through the Effects tab of the data dialog of the corresponding multi-effect evaporation operation.	1	Positive
◙ Mean Heat Transfer Area (m²) The average of the heat transfer areas of all the effects that comprise a single unit of this type. Used as the sizing variable of this equipment resource. The heat transfer areas of individual effects are shown in the Effects tab of the corresponding multi-effect evaporation operation’s data dialog.	0.0	Positive
○ Max Mean Heat Transfer Area (m²) The desired upper limit of the sizing variable. Used only in design mode to determine if multiple units are required.	900.0	Positive

Symbol Key: ○ User-specified value (always input); ● Calculated value (always output); ◙ Sometimes input, sometimes output

Sizing: Design Mode

In design mode, the software will size the unit based on the demand on mean heat transfer area by the multi-effect evaporation operation executed in the unit. If the mean heat transfer area exceeds the specification for the maximum mean heat transfer area then the software will assume multiple number of identical units (each with mean heat transfer area equally distributed) that are operated in parallel.

Sizing: Rating Mode

In rating mode, the mean heat transfer area of the unit and the number of units are provided by the user.

Costing

The equipment purchase cost is based on the mean heat transfer area and the number of effects. The built-in model is based on information available in D.E. Garrett’s Chemical Engineering Economics (New York: Van Nostrand Reinhold, 1989).

For more information on this equipment, see Multi-Effect Evaporator.

For information on the left-hand side variables and options, see Equipment Data Dialog: Equipment tab.