A thermal management system for a vehicle, the system comprising: a tank for storing a coolant; a heat exchanger, located downstream of the tank on a first conduit, for placing the coolant in a heat exchange relationship with a heat load from the vehicle such that the coolant vaporizes; a pump, located between the tank and the heat exchanger on the first conduit, for pumping the coolant from the tank to the heat exchanger; a first valve, located downstream of the heat exchanger on the first conduit, for regulating pressure within the heat exchanger and controlling exhaustion of the vaporized coolant from the vehicle; and a compressor, located between the heat exchanger and the first valve on the first conduit, for reducing pressure within the heat exchanger; characterised in that the thermal management system further comprises a second conduit having an inlet and an outlet, the inlet fluidly connected to the first conduit downstream of the heat exchanger and upstream of the first valve, and the outlet fluidly connected to the first conduit downstream of the pump and upstream of the heat exchanger; a condenser, located on the second conduit, for placing the vaporized coolant in a heat exchange relationship with a cool load from the vehicle such that the coolant condenses; a second valve, located on the second conduit between the inlet and the condenser, for regulating flow of vaporized coolant to the condenser; and an expansion valve, located on the second conduit between the condenser and the outlet, for expanding the condensed coolant; wherein the second valve is configured to be at least partially open when the vehicle is operating below peak heat load, and is configured to be at least partially closed when the vehicle is operating at peak heat load. a tank for storing a coolant; a heat exchanger, located downstream of the tank on a first conduit, for placing the coolant in a heat exchange relationship with a heat load from the vehicle such that the coolant vaporizes; a pump, located between the tank and the heat exchanger on the first conduit, for pumping the coolant from the tank to the heat exchanger; a first valve, located downstream of the heat exchanger on the first conduit, for regulating pressure within the heat exchanger and controlling exhaustion of the vaporized coolant from the vehicle; and a compressor, located between the heat exchanger and the first valve on the first conduit, for reducing pressure within the heat exchanger; characterised in that the thermal management system further comprises a second conduit having an inlet and an outlet, the inlet fluidly connected to the first conduit downstream of the heat exchanger and upstream of the first valve, and the outlet fluidly connected to the first conduit downstream of the pump and upstream of the heat exchanger; a condenser, located on the second conduit, for placing the vaporized coolant in a heat exchange relationship with a cool load from the vehicle such that the coolant condenses; a second valve, located on the second conduit between the inlet and the condenser, for regulating flow of vaporized coolant to the condenser; and an expansion valve, located on the second conduit between the condenser and the outlet, for expanding the condensed coolant; wherein the second valve is configured to be at least partially open when the vehicle is operating below peak heat load, and is configured to be at least partially closed when the vehicle is operating at peak heat load.