docs: def Cavallini_Smith_Zecchin(m, x, D, rhol, rhog, mul, mug, kl, Cpl):
      r'''Calculates heat transfer coefficient for condensation
      of a fluid inside a tube, as presented in
      [1]_, also given in [2]_ and [3]_.
  
      .. math::
          Nu = \frac{hD_i}{k_l} = 0.05 Re_e^{0.8} Pr_l^{0.33}
          
          Re_{eq} = Re_g(\mu_g/\mu_l)(\rho_l/\rho_g)^{0.5} + Re_l
  
          v_{gs} = \frac{mx}{\rho_g \frac{\pi}{4}D^2}
  
          v_{ls} = \frac{m(1-x)}{\rho_l \frac{\pi}{4}D^2}
  
      Parameters
      ----------
      m : float
          Mass flow rate [kg/s]
      x : float
          Quality at the specific interval [-]
      D : float
          Diameter of the channel [m]
      rhol : float
          Density of the liquid [kg/m^3]
      rhog : float
          Density of the gas [kg/m^3]
      mul : float
          Viscosity of liquid [Pa*s]
      mug : float
          Viscosity of gas [Pa*s]
      kl : float
          Thermal conductivity of liquid [W/m/K]
      Cpl : float
          Constant-pressure heat capacity of liquid [J/kg/K]
  
      Returns
      -------
      h : float
          Heat transfer coefficient [W/m^2/K]
  
      Notes
      -----
  
      Examples
      --------
      >>> Cavallini_Smith_Zecchin(m=1, x=0.4, D=.3, rhol=800, rhog=2.5, mul=1E-5, mug=1E-3, kl=0.6, Cpl=2300)
      5578.218369177804
      
      References
      ----------
      .. [1] A. Cavallini, J. R. Smith and R. Zecchin, A dimensionless correlation
         for heat transfer in forced convection condensation, 6th International 
         Heat Transfer Conference., Tokyo, Japan (1974) 309-313. 
      .. [2] Kakaç, Sadik, ed. Boilers, Evaporators, and Condensers. 1st. 
         Wiley-Interscience, 1991.
      .. [3] Balcılar, Muhammet, Ahmet Selim Dalkılıç, Berna Bolat, and Somchai 
         Wongwises. "Investigation of Empirical Correlations on the Determination
         of Condensation Heat Transfer Characteristics during Downward Annular 
         Flow of R134a inside a Vertical Smooth Tube Using Artificial 
         Intelligence Algorithms." Journal of Mechanical Science and Technology 
         25, no. 10 (October 12, 2011): 2683-2701. doi:10.1007/s12206-011-0618-2.
      '''
      Prl = Prandtl(Cp=Cpl, mu=mul, k=kl)
      Vl = m*(1-x)/(rhol*pi/4*D**2)
      Vg = m*x/(rhog*pi/4*D**2)
      Rel = Reynolds(V=Vl, D=D, rho=rhol, mu=mul)    
      Reg = Reynolds(V=Vg, D=D, rho=rhog, mu=mug)
      '''The following was coded, and may be used instead of the above lines,
      to check that the definitions of parameters here provide the same results
      as those defined in [1]_.
      G = m/(pi/4*D**2)
      Re = G*D/mul
      Rel = Re*(1-x)
      Reg = Re*x/(mug/mul)'''
      Reeq = Reg*(mug/mul)*(rhol/rhog)**0.5 + Rel
      Nul = 0.05*Reeq**0.8*Prl**0.33
      return Nul*kl/D