def alpha_liq_deph(Nu_deph, lyambda_coolwater, d_inner_deph):
    """
    Calculates the coefficent of heat transfer(alpha) from liquid to wall of pipe.
    Parameters
    ----------
    Nu_deph : float
        The Nusselt criterion, [dimensionless]
    lyambda_coolwater : float
        The thermal conductivity of cool water, [W / (m * degreec celcium)]
    d_inner_deph : float
        The diametr of inner pipe, [m]
    Returns
    -------
    alpha_liq_deph : float
        The coefficent of heat transfer(alpha), [W / (m**2 * degrees celcium)]
    References
    ----------
    Романков, формула 4.11, стр.150
    """          
    return Nu_deph * lyambda_coolwater / d_inner_deph