Prandtl Numbers with prcalc and mixpr

The Prandtl Number = cp*m/k is a dimensionless quantity that plays an important role in heat exchange. The symbols in this definition stand for:

The first program is called prcalc. It has the same arguments as the other property calc programs.

>>help prcalc

  prcalc(T,index) finds the Prandtl number of low density gases
  Uses ktpcalc, mucalc functions and mw, cpv data

Here are the results for the compounds in the data file transp:

>>prcalc(273.2)
ans =
    0.7759  <-- BS&L reports in Table 8.3-1 0.78 for CO2
    0.7382  <-- BS&L reports in Table 8.3-1 0.74 for O2
    0.7367  <-- BS&L reports in Table 8.3-1 0.73 for N2
    0.6667  <-- BS&L reports in Table 8.3-1 0.66 for Ne

The program mixpr finds the Prandtl Number for a low density gas mixture.

>>help mixpr

  mixpr(zs,T,j) finds the Prandtl number for a low density gas mixture
  zs gives the mol fraction of each compound
  T gives the temperature in the units of Tdeg
  j gives the indices of the compounds (if missing it includes
    all compounds.  zs must be consistent with j.
  uses mixkt and mixmu together with cpv and mw.

Here is an example of its use, but BS&L does not give an example to compare with the result.

>>mixpr([0.133 0.039 0.828],293,1:3)
ans =
    0.7357