Waste heat recovery system

A waste heat recovery system, comprising:

• a Rankine cycle in which a refrigerant circulates in a refrigerant pump, an evaporator, an expander, and a condenser in sequence;
• a controller for controlling the Rankine cycle,
• wherein the waste heat recovery system uses waste heat from an internal combustion engine as a heating source for the evaporator;
• a set including the expander and the condenser and at least one different set including a different expander and a different condenser are connected in parallel with each other;
• a device for stopping an operation of the expander in the different set connected in parallel;
• a pressure sensor in an inlet of the evaporator and a temperature sensor in an outlet of the evaporator,
• wherein the controller sets or releases at least one of the operation stopping devices such that a measured value of the temperature sensor reaches a prescribed temperature value which is set in advance and is equal to or less than a thermal decomposition temperature of the refrigerant, and
• wherein the controller controls a rotational speed of the refrigerant pump such that a measured value of the pressure sensor reaches a prescribed pressure value which is set in advance.