Dimensionless quantity calculated as the ratio of momentum diffusivity (kinematic viscosity)
\nu to thermal diffusivity
a:
| (1) | {\rm Pr} = \frac{\nu}{a} |
It is dynamic property of the substance at a given pressure and temperature:
{\rm Pr} = {\rm Pr}(p, T).
High values mean that heat convection dominates heat conduction.
| Material | Conditions | |
|---|---|---|
| Air | 0.71 | STP |
| Oxygen | 0.63 | STP |
| Natural gas | 0.70 ÷ 0.72 | wide range of temperature and pressure |
| Water | 7.56 | STP |
| Light oil | 600 | STP |
See also
Physics / Thermodynamics / Heat Transfer
[ Dimensionless Heat Transfer Numbers ]