Transient Process = Unsteady Process

Transient Process

(or unsteady process) :
Transient processes can be very complex. Therefore, we will only consider processes in which we can assume uniform flow and uniform state.

Uniform Flow

Uniform State




Flow diagram of an open system in which the mass within the system changes with time.
A process in which one or more properties or process variables change as a function of time.
The properties and flowrates of all inlet and outlet streams are constant over the cross-sectional area for flow and are also constant with respect to time.
(Equation., Equation., Equation., and Equation. are constant)
The state of the mass within the system is uniform. At all times, the properties of the outlet stream are exactly the same as the properties of the system at that point in time. The properties of the system do change with time, but they are always the same as the properties of the outlet stream.
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Ch 5, Lesson D, Page 1 - Transient Process = Unsteady Process