To sum up, for a heat pump system under a low evaporating
temperature or a high condensing temperature condition,
which is far away from the rated condition, the decrease
of the inlet specific enthalpy will largely increase the cooling
capacity of the evaporator but has little influence on the
evaporating temperature and refrigerant flow rate on the low
pressure side. That is to say, the smaller the inlet specific
enthalpy is, the larger the cooling capacity of the evaporator
is, which is the basis of the following optimal analysis