NU_VHELIX_PRR
This function computes the Nusselt number for natural convection around a vertical helical coil using the Prabhanjan-Rennie-Raghavan correlation. It models external convection from the coil to surrounding fluid in a vessel.
The formulation is expressed in Rayleigh number form, where \mathrm{Ra} = \mathrm{Pr}\,\mathrm{Gr} for the selected characteristic length and temperature definition.
\mathrm{Nu}_H = 0.0749\,\mathrm{Ra}_H^{0.3421}
Excel Usage
=NU_VHELIX_PRR(Pr, Gr)Pr(float, required): Prandtl number at film temperature (-).Gr(float, required): Grashof number at film temperature (-).
Returns (float): Nusselt number for a vertical helical coil, or error message if invalid.
Example 1: Prabhanjan-Rennie-Raghavan correlation example
Inputs:
| Pr | Gr |
|---|---|
| 4.4 | 100000000000 |
Excel formula:
=NU_VHELIX_PRR(4.4, 100000000000)Expected output:
720.621
Example 2: Prabhanjan-Rennie-Raghavan correlation at mid range
Inputs:
| Pr | Gr |
|---|---|
| 6 | 50000000000 |
Excel formula:
=NU_VHELIX_PRR(6, 50000000000)Expected output:
632.128
Example 3: Prabhanjan-Rennie-Raghavan correlation at higher Rayleigh
Inputs:
| Pr | Gr |
|---|---|
| 8 | 200000000000 |
Excel formula:
=NU_VHELIX_PRR(8, 200000000000)Expected output:
1120.76
Example 4: Prabhanjan-Rennie-Raghavan correlation at lower Rayleigh
Inputs:
| Pr | Gr |
|---|---|
| 5 | 20000000000 |
Excel formula:
=NU_VHELIX_PRR(5, 20000000000)Expected output:
434.092
Python Code
Show Code
from ht.conv_free_enclosed import Nu_vertical_helical_coil_Prabhanjan_Rennie_Raghavan as ht_Nu_vertical_helical_coil_Prabhanjan_Rennie_Raghavan
def Nu_VHelix_PRR(Pr, Gr):
"""
Calculate the Nusselt number for natural convection around a vertical helical coil using the Prabhanjan-Rennie-Raghavan correlation.
See: https://ht.readthedocs.io/en/latest/ht.conv_free_enclosed.html
This example function is provided as-is without any representation of accuracy.
Args:
Pr (float): Prandtl number at film temperature (-).
Gr (float): Grashof number at film temperature (-).
Returns:
float: Nusselt number for a vertical helical coil, or error message if invalid.
"""
try:
return ht_Nu_vertical_helical_coil_Prabhanjan_Rennie_Raghavan(Pr=Pr, Gr=Gr)
except Exception as e:
return f"Error: {str(e)}"