Section 1.2.3: Glossary of Chemical Engineering Terms

This module was written by chemical engineers, and most of the examples have been drawn from this field. Several terms used in the module may confuse people unfamiliar with this discipline. This section is intended to explain some of these terms in a simple manner.

• Adiabatic
- without loss or gain of heat
• Azeotrope
- a specific mixture of components, which at a given pressure cannot be separated by distillation, i.e. the liquid and vapour phases have the same compositions.
• Bubble Point
- upon heating a liquid mixture, this is the point at which bubbles first appear.
• CSTR
- Continuous Stirred Tank Reactor. This may be thought of as a tank to which reactants flow in, and products flow out. In an ideal CSTR the contents of the reactor are uniformly distributed.
• Dew Point
- upon cooling a vapour mixture, this is the point at which droplets of liquid first appear.
• Heterogeneous
- containing more than one phase.
• Homogeneous
- containing a single phase.
• Immiscible
- Two liquids are said to be immiscible, if when added together they do not mix but form two separate liquid phases.
• PFR
- Plug Flow Reactor. This may be thought of as a long pipe to which the reactants flow in, and the products flow out. In an ideal PFR, the components will be distributed axially, but will have uniform radial distribution.
• Reynold's Number
- This is a number which characterises flow. If the Reynold's number is low (under approximately 1800) then the flow is said to be laminar. This may be thought of as the fluid flowing in layers. If the Reynold's number is high (over approximately 2300) then the flow is said to be turbulent. Turbulent flow is considered to be well mixed.
• Vapour Pressure
- Vapour evaporates at the surface of a liquid. The pressure it exerts is known as vapour pressure. The higher the temperature the greater the vapour pressure.