A first expansion valve is provided in a first refrigerant circulation passage through which the refrigerant discharged from a compressor is able to circulate by passing sequentially through an external heat exchanger and an evaporator and returning to the compressor. A second expansion valve is provided in a second refrigerant circulation passage through which the refrigerant discharged from the compressor is able to circulate by passing sequentially through an auxiliary condenser and the external heat exchanger and returning to the compressor. The second expansion valve regulates the valve opening degree such that the refrigerant state at an inlet side of the compressor during a heating operation is in a range where the dryness of refrigerant is greater than or equal to 0.9 and the superheat of refrigerant is less than or equal to 5 C.

A rankine cycle system (1), a rankine-refrigeration cycle system (2) and a refrigerated vehicle are disclosed. The rankine cycle system (1) comprises a first evaporator (11), an expander (12), a condenser (13) and a refrigerant pump (14) connected in sequence to form a cycle, wherein the rankine cycle system (1) further comprises an electric heating device (15) connected between the refrigerant pump (14) and the expander (12) for heating the refrigerant. When the rankine cycle system (1) has no waste heat source, the present application can continue to provide energy to the rankine cycle through the electric heating device (15), thereby enabling the expander (12) to continuously and effectively output mechanical work. Even without a waste heat source, the rankine cycle can still operate normally, thus adapting to more operating conditions.