NU_PLATE_KHAN_KHAN
This function estimates the Nusselt number for single-phase convection in chevron-style plate heat exchangers using the Khan and Khan correlation. It relates convective heat transfer to Reynolds number, Prandtl number, and chevron angle.
The correlation form is:
Nu = \left(c_1\frac{\beta}{\beta_{max}} + c_2\right)Re^{\left(c_3\frac{\beta}{\beta_{max}} + c_4\right)}Pr^{0.35}
where \beta is chevron angle and the constants are empirical. This function is typically applied within the reported validity region for Reynolds number, Prandtl number, and plate angles.
Excel Usage
=NU_PLATE_KHAN_KHAN(Re, Pr, chevron_angle)Re(float, required): Reynolds number with respect to hydraulic diameter of the channels (-).Pr(float, required): Prandtl number calculated with bulk fluid properties (-).chevron_angle(float, required): Plate chevron angle relative to flow direction (degrees).
Returns (float): Nusselt number with respect to hydraulic diameter, or error message if invalid.
Example 1: Example from documentation
Inputs:
| Re | Pr | chevron_angle |
|---|---|---|
| 1000 | 4.5 | 30 |
Excel formula:
=NU_PLATE_KHAN_KHAN(1000, 4.5, 30)Expected output:
38.4088
Example 2: Mid-range Reynolds and Prandtl numbers
Inputs:
| Re | Pr | chevron_angle |
|---|---|---|
| 1500 | 3.5 | 45 |
Excel formula:
=NU_PLATE_KHAN_KHAN(1500, 3.5, 45)Expected output:
70.1524
Example 3: Higher chevron angle with larger Reynolds number
Inputs:
| Re | Pr | chevron_angle |
|---|---|---|
| 2000 | 5 | 60 |
Excel formula:
=NU_PLATE_KHAN_KHAN(2000, 5, 60)Expected output:
149.382
Example 4: Lower Reynolds number within recommended range
Inputs:
| Re | Pr | chevron_angle |
|---|---|---|
| 500 | 4 | 40 |
Excel formula:
=NU_PLATE_KHAN_KHAN(500, 4, 40)Expected output:
27.6417
Python Code
Show Code
from ht.conv_plate import Nu_plate_Khan_Khan as ht_Nu_plate_Khan_Khan
def Nu_plate_Khan_Khan(Re, Pr, chevron_angle):
"""
Calculate Nusselt number for single-phase flow in a chevron-style plate heat exchanger (Khan and Khan).
See: https://ht.readthedocs.io/en/latest/ht.conv_plate.html
This example function is provided as-is without any representation of accuracy.
Args:
Re (float): Reynolds number with respect to hydraulic diameter of the channels (-).
Pr (float): Prandtl number calculated with bulk fluid properties (-).
chevron_angle (float): Plate chevron angle relative to flow direction (degrees).
Returns:
float: Nusselt number with respect to hydraulic diameter, or error message if invalid.
"""
try:
result = ht_Nu_plate_Khan_Khan(Re=Re, Pr=Pr, chevron_angle=chevron_angle)
return float(result)
except Exception as e:
return f"Error: {str(e)}"