Frequently Used Notations

This is an ongoing list of the frequently used notations and their units. Please feel free to add variables that you find yourself always looking for.

Symbol	Description	English Units	SI Units
Cp	Specific Heat with constant pressure	Btu/(lbm°F)	kJ/kg·K
Cv	Specific Heat with constant volume	Btu/(lbm°F)	kJ/kg·K
DAB	Molecular diffusivity of substance A through substance B	ft2/s	m2/s
E**	Activation Energy	cal/g·mol	J/kg·mol
F	Frictional Loss	ft·lbf/lbm	J/kg
F	Force	lbf	N
g	Gravity	ft/s2	m/s2
h	Head	ft·lbf/lbm	J/kg
h	Heat Transfer Coefficient	btu/h·ft2·°F	W/m2·K
H	Enthalpy	btu/lbm	J/kg
jA	Mass Flux of A		kg·s/m2
JA	Molar Flux of A		kg·mol/s·m2
k	Thermal Conductivity	btu/hr·ft·°F	W·m/K
L	Length	ft	m
m	Mass Flow Rate	kg/s	lbm/s
MWA	Molecular Weight of A	lbm/lb·mol	kg/kg·mol
NPSH	Net Positive Suction Head	ft	m
P	Pressure	lbf/ft2, atm, psia	N/m2, Pa
pv	Vapor Pressure	lbf/ft2, atm, psia	N/m2, Pa
q, Q, V̇	Volumetric Flow Rate	ft3/s	m3/s
r	radius	ft	m
Sp	Particle Surface Area	ft2	m2
ν	Velocity	ft/s	m/s
ρ	Density	lbm/ft3	kg/m3
τ	Shear Stress	lbf/ft2	N/m2
λ	Latent Heat	btu/lbm	J/kg
μ	Viscosity	P(Poise)	Pa*s or kg/m*s
U	Internal Energy	btu/lbm	J/kg
Example	Example	Example	Example

References

• Geankoplis, Christie John. Transport Processes and Separation Process Principles. Pearson Education Inc, 2015. Book.
• Engineering ToolBox, (2003).

Catherine Lintner (talk)