docs: def Nu_plate_Khan_Khan(Re, Pr, chevron_angle):
      r'''Calculates Nusselt number for single-phase flow in a 
      Chevron-style plate heat exchanger according to [1]_.
      
      .. math::
          Nu = \left(0.0161\frac{\beta}{\beta_{max}} + 0.1298\right)
          Re^{\left(0.198 \frac{\beta}{\beta_{max}} + 0.6398\right)} 
          Pr^{0.35} 
                  
      Parameters
      ----------
      Re : float
          Reynolds number with respect to the hydraulic diameter of the channels,
          [-]
      Pr : float
          Prandtl number calculated with bulk fluid properties, [-]
      chevron_angle : float
          Angle of the plate corrugations with respect to the vertical axis
          (the direction of flow if the plates were straight), between 0 and
          90. Many plate exchangers use two alternating patterns; use their
          average angle for that situation [degrees]
  
      Returns
      -------
      Nu : float
          Nusselt number with respect to `Dh`, [-]
  
      Notes
      -----
      The viscosity correction power is recommended to be the blanket
      Sieder and Tate (1936) value of 0.14.
      
      The correlation is recommended in the range of Reynolds numbers from
      500 to 2500, chevron angles between 30 and 60 degrees, and Prandtl
      numbers between 3.5 and 6.
  
      Examples
      --------
      >>> Nu_plate_Khan_Khan(Re=1000, Pr=4.5, chevron_angle=30)
      38.40883639103741
      
      References
      ----------
      .. [1] Khan, T. S., M. S. Khan, Ming-C. Chyu, and Z. H. Ayub. "Experimental
         Investigation of Single Phase Convective Heat Transfer Coefficient in a 
         Corrugated Plate Heat Exchanger for Multiple Plate Configurations." 
         Applied Thermal Engineering 30, no. 8 (June 1, 2010): 1058-65.
         https://doi.org/10.1016/j.applthermaleng.2010.01.021. 
      '''
      beta_max = 60.
      beta_ratio = chevron_angle/beta_max
      Nu = (0.0161*beta_ratio + 0.1298)*Re**(0.198*beta_ratio + 0.6398)*Pr**0.35
      return Nu