Cont. Stoich. Reaction in an Electrowinning Cell: Oper. Conds Tab

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

◙ ExitTemperature (^oC) The temperature of the equipment contents after the end of the operation.	25.0	Positive
◙ Heating Duty (kcal/h) The heat transfer rate that must be added to the system using either a heating agent or electricity.	0.0	Positive
◙ Cooling Duty (kcal/h) The heat transfer rate that must be removed from the system using either a cooling agent or electricity.	0.0	Positive
○ Heat Transfer Agent Name Indicates the heat transfer agent used for the operation. Click on the list box to bring up a list of available heat transfer agents in order to select one.	<Chilled Water>	Any Heat Transfer Agent
● Inlet Temp. (^oC) The inlet temperature of the heat transfer agent.	0.0	Positive
● Outlet Temp. (^oC) The outlet temperature of the heat transfer agent.	0.0	Positive
● Rate (kg/h) The mass flow rate of the heat transfer agent.	0.0	Positive
○ Heat Transfer Efficiency(%) The heat transfer agent efficiency. If the value is lower than 100% then an increased heat transfer agent amount will be calculated by the program to satisfy the required duty.	100.0	[0,100)
○ Power Type Indicates the power type that is used by the operation. Click on the list box to bring up a list of available power types in order to select one.	<Std Power>	Any Power Type
● Power (for Heating/Cooling) (W) The power consumed by this operation (per cycle) either for heating or cooling.	0.0	Positive
○ Electric Heating Efficiency(%) The efficiency of heat transfer if electricity is used for heating. If the value is lower than 100% then an increased electricity consumption will be calculated by the program to satisfy the required heating duty.	90.0	[0,100)
○ Coefficient of Performance The ratio of cooling duty to electricity consumption used to calculate the electricity consumption if cooling is required and electricity is used for cooling.	4.5	Positive
● Additives (Adjustable) Stream Indicates the name of the input stream that is connected to the additives (bottom) input port. If an input stream is already present at that port, then the button next to the selection is active. Click on that button to bring up the attached stream’s simulation dialog in order to provide the composition of the material being charged.	<None>	Dedicated Input Port
◙ Additives/Feed Ratio Based on Mass The ratio of additives mass flow rate to feed mass flow rate.	1.0	Positive
◙ Additives/Feed Ratio Based on Volume The ratio of additives volumetric flow rate to feed volumetric flow rate.	1.0	Positive
○ Ignore Water Evaporation? Check this box to ignore the effect of water evaporation on the material and energy balances for this operation.	Yes	Yes/No
○ Water Component Indicates the pure component used to represent the water substance. Click on the list box to bring up a list of available components in order to select one.	<Water>	Any Pure Component
○ Water Evaporation (%) The fraction of water contained in the equipment contents at the beginning of the operation that is evaporated, expressed as percentage.	0.0	[0,100)
○ Air Velocity (m/s) The velocity of surrounding air.	0.5	Positive
○ Air Temp. (^oC) The temperature of surrounding air.	25.0	Positive
○ Air Relative Humidity (%) The relative humidity of surrounding air, expressed as a percentage.	60.0	0-100
● Operating Pressure (atm) The pressure in the electrowinning cell.	1.0	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 Cont. Stoich. Reaction in an Electrowininng Cell: Modeling Calculations.

•Thermal Mode Options...

Three thermal modes of operation are available: “Set Final Temperature”, “Adiabatic”, and “Set Duty”. If the final temperature is set, then the program will calculate the required heating or cooling duty. If a duty or adiabatic mode is set, then the program will calculate the final temperature.

•Heating/Cooling Utility Options...

If you set the final temperature or the duty, then you must also select the type of utility that is going to be used (heat transfer agent or electricity) in order to achieve the required final temperature or duty. If you choose to use electricity, then you can specify either the efficiency of electric heating (which is used when the electricity is used for heating) or the coefficient of performance (which is used when the electricity is used for cooling).

•Additives Stream Flow Specification Options...

You may either set the ratio of additives mass to feed mass or the ratio of additives volume to feed volume.

•Water Evaporation Options...

You may choose to ignore or consider water evaporation. If you choose to consider water evaporation, then you must select the pure component that represents water in this operation, and you can either set the water evaporation percent directly, or let the program estimate it using a simplified built-in model that is based on the inlet temperature and on the temperature, relative humidity and velocity of surrounding air.