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It is dynamic property of the substance at a given pressure and temperature:
.LaTeX Math Inline body --uriencoded--%7B\rm Pr%7D = %7B\rm Pr%7D(p, T)
High values mean that heat convection dominates heat conduction.
For most gases over a wide range of temperature and pressure, Prandtl number is approximately constant at around
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For water in :
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| 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 |
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