HEAT REJECTION BASED ON DYNAMIC CONTROL OVER A RANGE OF ALTITUDES

A heat rejection system (100) in a vehicle includes a heat exchanger (110) to take in input coolant (175) and to output a warmed coolant (115), a heat of vaporization device (HVD), and a heat of fusion device (HFD). The heat rejection system also includes a controller (105) to direct the warmed coolant to the HVD or to the HFD based on an input. The input indicates altitude of the vehicle or ambient pressure.