Cold fuel cooling of intercooler and aftercooler

An aircraft powerplant cooling system operating with a first coolant, comprising:

• a front ram-air heat exchanger along a ram-air passageway, the front ram-air heat exchanger being configured to cool the coolant;
• a rear ram-air heat exchanger downstream of the front ram-air heat exchanger along the ram-air passageway, the front ram-air heat exchanger being downstream of the rear ram-air heat exchanger along a heat-exchanger coolant passageway such that the front ram-air heat exchanger is configured to further cool coolant received from the rear ram-air heat exchanger;
• a first thermal load downstream of the front ram-air heat exchanger, the first thermal load being configured to receive cooled coolant from the front ram-air heat exchanger, and being configured warm the received coolant and pass the warmed coolant downstream to the rear ram-air heat exchanger;
• a second thermal load;
• and
• a coolant manifold downstream from the rear ram-air heat exchanger and upstream from the front ram-air heat exchanger, the manifold being configured to split coolant received from the rear ram-air heat exchanger into a first stream directed to the front ram-air heat exchanger and a second stream directed to the second thermal load;
• wherein the second thermal load is configured to receive cooled coolant from the manifold, and to warm the received coolant and pass the warmed coolant downstream to the rear ram-air heat exchanger.

A powerplant for use in a range of flight conditions, comprising:

• a power converter configured to produce energy from a fuel and an oxidizer;
• a cryogenic fuel source for use by the power converter, the fuel source fuel being configured to provide the fuel at a temperature below ambient temperatures over the range of flight conditions;
• a first fuel heat exchanger configured to heat fuel from the fuel source using heat from a first cooling loop that includes a first heat source;
• a second fuel heat exchanger configured to heat fuel serially received from the first fuel heat exchanger, the second fuel heat exchanger using heat from a second cooling loop that includes a second heat source;
• and
• a control system configured to control the operation of the first and second cooling loops based on a temperature of the fuel that is received by the power converter
• wherein the second heat source is not on the first cooling loop, and wherein the first heat source is not on the second cooling loop.