Batch Freezing: Oper. Conds Tab

BatchFreezingOperConds.jpg
Variable Definitions, Ranges and Default Values

The following table shows a brief description of the variables appearing in this tab. The table also displays their default values and their generally acceptable range:

Variable

Default Value

Range

 

○ Final Temperature (oC)
The final temperature of vessel contents after the end of the operation.

0.0

Positive

○ Ignore Freezing Utility
Check this box to ignore the freezing utility type.

No

Yes/No

○ Name (of Freezing Agent)
Indicates the freezing agent used for the operation. Click on the list box to bring up a list of available freezing agents in order to select one.

<CaCl2 Brine>

Any Cooling Agent

● Inlet Temp. (of Freezing Agent) (oC)
The inlet temperature of the freezing agent.

-30.0

Positive

● Outlet Temp. (of Freezing Agent) (oC)
The outlet temperature of the freezing agent.

-20.0

Positive

● Rate (of Freezing Agent) (kg/h)
The mass flow rate of the freezing agent.

0.0

Positive

○ Heat Transfer Efficiency(%)
The heating agent consumption efficiency. Specify a value below 100% to account for heat losses to the surroundings when a heating agent is used.

90.0

[0,100)

● Duty (kcal/h)
The freezing duty of the operation (i.e., the heat transfer rate of the freezing agent).

0.0

Positive

○ Setup Time (min)
The amount of time (per cycle) spent before each operation is carried in preparation for the actual execution of the operation. It may involve actions like cleaning, vacuuming, setting up of equipment, etc. which the user opted not to model explicitly.

5.0

Positive

◙ Freezing Time (min)
The actual duration of the operation.

15.0

Positive

○ Ignore Labor?
Check this box to ignore labor for this operation. This option is used only if the process time is set by a master-slave relationship.

Yes

Yes/No

◙ Freezing Rate (oC/min)
The freezing rate of the vessel contents.

1.0

Positive

◙ Overall UA (kcal/h-oC)
The product of overall heat transfer coefficient and heat transfer area.

10500

Positive

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

Specification Choices / Comments

The following list describes the available specification choices in this tab; for more details on how these are implemented, see Batch Cooling: Modeling Calculations.

•If the Freezing Utility is ignored...

No energy balances are done.

•Duration options...

You can set the process time (cooling time), or have the process time calculated based on cooling rate, or match the duration of this operation to the duration of another operation by introducing a master-slave relationship between the two operations. There are two options for specifying the cooling rate: you can either specify a constant cooling rate or an exponential cooling rate (specify the overall UA). If you introduce a master-slave relationship, the program will match the setup time, the process time and the turnaround time of this operation (the ‘slave’) with the corresponding times of the reference operation (the ‘master’ operation). For more details on how to setup a master-slave relationship, see The Scheduling Tab.