def Q_feed(deltaT, F_mass, Cp, phi_vapor, r_feed):
    """
    Calculates the heat load of heat exchanger.
    Parameters
    ----------
    deltaT : float
        The difference temperatures between the initial and the ultimate temperatures of mix , [degrees celcium]
    F_mass : float
        The mass flow rate of feed [kg/s]
    Cp : float
        The heat capacity of mix [J/(kg * degrees C)]
    phi_vapor: float
        The part of vapor in feed, [dimensionless]
    r_feed : float
        The heat vaporazation of mix, [J/kg]
    Returns
    -------
    Q_feed : float
        The heat load of heat exchanger, [W] , [J/s]
    References
    ----------
    Дытнерский, формула 2.2, стр.45
    """   
    return F_mass * (Cp * deltaT + phi_vapor * r_feed)