Plate Heat Exchanger

[AndreasMatthias]

1. friction_plate_Martin_1999(Re, plate_enlargement_factor)

The second parameter of this function should be named chevron_angle (in radians) and not plate_enlargement_factor.

In Martin's equations an uppercase phi, $\Phi$, denotes the plate enlargement factor whereas a lowercase phi, $\phi$, denotes the chevron angle. The equations in the source code are correct, it's just the name of the parameter which is wrong or misleading.

Note, that chevron_angle must be given in radians here, whereas in friction_plate_Kumar() it is given in degree.

2. friction_plate_Martin_VDI(Re, plate_enlargement_factor)

1. Same as for friction_plate_Martin_VDI(). Second parameter should be named chevron_angle.

2. The equations for friction_plate_Martin_1999() and friction_plate_Martin_VDI() are almost the same. friction_plate_Martin_1999() calculates the Fanning friction factor and multiplies the result by 4 to return the Darcy friction factor, whereas friction_plate_Martin_VDI() calculates the Darcy friction factor directly. But there's one small discrepancy: In Martin 1999 the term 0.045⋅tanφ (in Fanning notation) would be 0.18⋅tanφ in Darcy notation, but in friction_plate_Martin_VDI() it is 0.28⋅tanφ. Is this a typo? According to the Heat Atlas, 2010, 2nd edition, the term 0.18⋅tanφ is correct. (But then friction_plate_Martin_1999() and friction_plate_Martin_VDI() calculate exactly the same.)

3. friction_plate_Kumar(Re, chevron_angle)

I believe chevron_angle in Kumar's equation is an angle with respect to the horizontal axis and not the vertical axis, as stated in the documentation. This is in contrast to Martin's equations where chevron_angle is an angle with respect to the vertical axis.