Holding

General Description

This operation can be used to represent Sample Analysis, Breaks and other operations that simply require some time. It has no impact on equipment contents.

Holding: Modeling Calculations

The user has the option to consider heat losses to the environment due to the temperature difference between the equipment contents and the ambient. Moreover, there is the option to keep the contents temperature constant by using a suitable heat transfer agent.

The final temperature of the contents in the case that the heat exchange rate is specified is given by:

HoldingFinalTemp.jpg 

eq. (A.35)

where:

      Tfinal is the final temperature of the contents

      Tinit is the initial temperature of the contents

      Tambient is temperature of the ambient

      ΔΤ = Tinit - Tambient

      mCp is the heat capacity of the equipment contents

      t is the process time

The product of the overall heat transfer coefficient times heat transfer area (UA) is calculated by:

HoldingUA.jpg 

eq. (A.36)

where Q is the heat rate (gain or loss) exchanged with the environment.

Holding: Interface

The interface of this operation has the following tabs:

      Oper. Cond’s, see Holding: Oper. Conds Tab

      Labor, etc, see Operations Dialog: Labor etc. Tab

      Description, see Operations Dialog: Description Tab

      Batch Sheet, see Operations Dialog: Batch Sheet Tab

      Scheduling, see Operations Dialog: Scheduling Tab