docs: def Lazarek_Black(m, D, mul, kl, Hvap, q=None, Te=None):
      r'''Calculates heat transfer coefficient for film boiling of saturated
      fluid in vertical tubes for either upward or downward flow. Correlation
      is as shown in [1]_, and also reviewed in [2]_ and [3]_.
      
      Either the heat flux or excess temperature is required for the calculation
      of heat transfer coefficient.
      
      Quality independent. Requires no properties of the gas.
      Uses a Reynolds number assuming all the flow is liquid.
  
      .. math::
          h_{tp} = 30 Re_{lo}^{0.857} Bg^{0.714} \frac{k_l}{D}
          
          Re_{lo} = \frac{G_{tp}D}{\mu_l}
      
      Parameters
      ----------
      m : float
          Mass flow rate [kg/s]
      D : float
          Diameter of the channel [m]
      mul : float
          Viscosity of liquid [Pa*s]
      kl : float
          Thermal conductivity of liquid [W/m/K]
      Hvap : float
          Heat of vaporization of liquid [J/kg]
      q : float, optional
          Heat flux to wall [W/m^2]
      Te : float, optional
          Excess temperature of wall, [K]
  
      Returns
      -------
      h : float
          Heat transfer coefficient [W/m^2/K]
  
      Notes
      -----
      [1]_ has been reviewed. 
      
      [2]_ claims it was developed for a range of quality 0-0.6,
      Relo 860-5500, mass flux 125-750 kg/m^2/s, q of 1.4-38 W/cm^2, and with a
      pipe diameter of 3.1 mm. Developed with data for R113 only.
  
      Examples
      --------
      >>> Lazarek_Black(m=10, D=0.3, mul=1E-3, kl=0.6, Hvap=2E6, Te=100)
      9501.932636079293
  
      References
      ----------
      .. [1] Lazarek, G. M., and S. H. Black. "Evaporative Heat Transfer, 
         Pressure Drop and Critical Heat Flux in a Small Vertical Tube with 
         R-113." International Journal of Heat and Mass Transfer 25, no. 7 (July 
         1982): 945-60. doi:10.1016/0017-9310(82)90070-9.
      .. [2] Fang, Xiande, Zhanru Zhou, and Dingkun Li. "Review of Correlations 
         of Flow Boiling Heat Transfer Coefficients for Carbon Dioxide."
         International Journal of Refrigeration 36, no. 8 (December 2013): 
         2017-39. doi:10.1016/j.ijrefrig.2013.05.015.
      .. [3] Bertsch, Stefan S., Eckhard A. Groll, and Suresh V. Garimella. 
         "Review and Comparative Analysis of Studies on Saturated Flow Boiling in
         Small Channels." Nanoscale and Microscale Thermophysical Engineering 12,
         no. 3 (September 4, 2008): 187-227. doi:10.1080/15567260802317357.
      '''
      G = m/(pi/4*D**2)
      Relo = G*D/mul
      if q:
          Bg = Boiling(G=G, q=q, Hvap=Hvap)
          return 30*Relo**0.857*Bg**0.714*kl/D
      elif Te:
          # Solved with sympy
          return 27000*30**(71/143)*(1./(G*Hvap))**(357/143)*Relo**(857/286)*Te**(357/143)*kl**(500/143)/D**(500/143)
      else:
          raise Exception('Either q or Te is needed for this correlation')