Dynamics Flashcards
What is a continuous process?
It is an open system where there is a continuous flow of feedstock material into a process, and continuous product flow. They are usually designed to operate at steady state.
What is a periodic process?
A continuous process which have periodic variations in material input to a process unit, but multiple units allow continuous overall feed input and product output.
What is a lumped process?
At any given time, the operating conditions (P, T, composition) inside process equipment are the same at all points within the equipment.
What is a distributive process?
The operating conditions vary not only with time but also position in the equipment due to imperfect mixing.
How do you calculate the number of degrees of freedom?
Number of model variables - number of independent model equations
What is a batch process?
It’s a closed system where feedstock is charged into the vessel at the start of processing, and products removed at the end.
What is space-time?
The average time that a molecule stays in the system. It’s calculated by V/q.
What is the extent of reaction?
The actual amount of material reacted or produced, but is normalised with the stoichiometric coefficients so that it’s value is component dependent.
What is internal, kinetic and potential energy?
Internal is the energy due to the random movement of the molecules and atoms of the fluid, and the intermolecular / interatomic forces.
Kinetic is the energy representing the bulk motion of the fluid, e.g. Caused by external agitation in a tank.
Potential is the energy possessed by the fluid by virtue of it’s position in a gravitational field.
What is steady state?
The condition of system where all variation with time has ceased.
What is the perturbation analysis?
It allows is to study the response of a system, initially at steady state, to a disturbance.
What is the difference between intensive and extensive variables?
Intensive variables don’t depend on system size, whereas extensive variables do.
