AIRCRAFT WITH THERMAL ENERGY STORAGE SYSTEM
A thermal energy system for use with an aircraft includes a cooling loop and a cooler. The cooling loop includes a fluid conduit and a pump configured to move fluid through the fluid conduit to transfer heat from a heat source to the fluid in the fluid conduit to cool the heat source. The cooler includes an air-stream heat exchanger located in a duct and is in thermal communication with the fluid conduit to transfer heat between the fluid in the cooling loop and the air passing through the duct.
1 . A thermal energy system for use with an aircraft, the thermal energy system comprising
a heat source,
a cooling loop having a fluid conduit and a pump configured to move fluid through the fluid conduit to transfer heat from the heat source to the fluid to cool the heat source,
a cooler that includes a duct configured to conduct air through the duct and an air-stream heat exchanger located in the duct and in thermal communication with the fluid in the cooling loop to transfer heat between the cooling loop and the air conducted through the duct, and
a thermal-storage fuel system that includes a first fuel tank configured to store fuel therein and a fuel-tank heat exchanger in thermal communication with the fluid and configured to transfer heat between the fluid in the cooling loop and fuel stored in the first fuel tank.
2 . The thermal energy system of claim 1 , wherein the cooling loop is structured to conduct the fluid heated from the heat source first through the air-stream heat exchanger in the duct and then to through the fuel-tank heat exchanger after the air-stream heat exchanger.
3 . The thermal energy system of claim 1 , wherein the thermal-storage fuel system further includes a second fuel tank in fluid communication with the first fuel tank and the second fuel tank configured to store fuel at a temperature that is different from a temperature of the fuel in the first fuel tank.
4 . The thermal energy system of claim 3 , wherein the thermal storage fuel system further includes an engine-fuel unit configured to receive fuel from the second fuel tank and deliver the fuel to an engine, the engine-fuel unit is in thermal communication with the cooling loop to transfer heat between the fluid in the cooling loop and the fuel in the engine-fuel unit.
5 . The thermal energy system of claim 4 , wherein the engine-fuel unit includes a valve system in fluid communication with the second fuel tank and an engine-fuel heat exchanger in thermal communication with the valve system and the cooling loop to transfer heat between the fluid in the cooling loop and the fuel from the second fuel tank, and wherein the valve system is configured vary a flow of fuel through the engine-fuel heat exchanger to deliver fuel to the engine at an engine-fuel unit predetermined threshold temperature.
6 . The thermal energy system of claim 5 , wherein the valve system includes a mix valve, a first conduit in fluid communication between the mix valve and the second fuel tank to deliver fuel having a first temperature to the mix valve, and a second conduit in fluid communication between the mix valve and the second fuel tank, wherein the engine-fuel heat exchanger is in thermal communication with the second conduit to cause the second conduit to deliver fuel having a second temperature to the mix valve, and wherein the mix valve is configured to vary a first flow rate of fuel from the first conduit and a second flow rate of fuel from the second conduit to provide a mixed stream of fuel having a third temperature that is less than or equal to the engine-fuel unit predetermined threshold temperature.
7 . The thermal energy system of claim 5 , wherein the cooling loop is structured to conduct the fluid heated from the heat source first through the engine-fuel heat exchanger, through the air-stream heat exchanger after the engine-fuel heat exchanger, and through the fuel-tank heat exchanger after the air-stream heat exchanger.
8 . The thermal energy system of claim 1 , wherein the cooling loop includes a valve connected to the fluid conduit and configured to selectively cause at least a portion of a flow of fluid in the cooling loop to bypass the fuel-tank heat exchanger.
9 . The thermal energy system of claim 8 , wherein the cooling loop includes modulating valves connected to the fluid conduit and configured to vary the flow of fluid in the cooling loop through the air-stream heat exchanger.
10 . The thermal energy system of claim 1 , further comprising a control system configured to selectively vary a flow of the fluid in the cooling loop through the air-stream heat exchanger and the fuel-tank heat exchanger to maintain a temperature of the heat source below a predetermined heat load temperature, and wherein the control system is configured to vary the predetermined heat load temperature throughout a flight cycle of the aircraft.
11 . The thermal energy system of claim 10 , wherein the control system is configured to measure the heat transfer between the fluid and the fuel in the first fuel tank, compare the heat transfer measured to a predetermined heat rejection schedule, and selectively vary the flow of fluid in the cooling loop through the fuel-tank heat exchanger in response to the heat transfer measured being different from the predetermined heat rejection schedule.
12 . The thermal energy system of claim 1 , wherein the cooler is a ram air cooler and the duct is configured to receive air from atmosphere around the aircraft during forward movement of the aircraft relative to ground and is free of any air mover.
13 . A method comprising
providing a thermal energy system for use with an aircraft including a cooling loop, a cooler, and a thermal-storage fuel system, the cooling loop having a fluid conduit and a pump configured to move fluid through the fluid conduit, the cooler including a duct configured to conduct air through the duct and an air-stream heat exchanger located in the duct and in thermal communication with the fluid in the cooling loop to transfer heat between the cooling loop and the air conducted through the duct, and the thermal-storage fuel system including a first fuel tank configured to store fuel therein and a fuel-tank heat exchanger in thermal communication with the fluid in the cooling loop,
conducting the fluid through the cooling loop to transfer heat between a heat source and the fluid in the cooling loop,
conducting the fluid in the cooling loop to the air-stream heat exchanger to transfer heat between the fluid in the cooling loop and the air passing through the duct, and
conducting the fluid in the cooling loop to the fuel-tank heat exchanger to transfer heat between the fluid in the cooling loop and fuel stored in the first fuel tank.
14 . The method of claim 13 , further comprising selectively varying a flow of the fluid in the cooling loop through the air-stream heat exchanger and a flow of the fluid through the fuel-tank heat exchanger to maintain a temperature of the heat source below a predetermined heat load temperature.
15 . The method of claim 13 , wherein the thermal-storage fuel system further includes a second fuel tank in fluid communication with the first fuel tank and the second fuel tank is configured to store fuel at a temperature that is different from a temperature of the fuel in the first fuel tank.
16 . The method of claim 15 , wherein the thermal-storage fuel system further includes an engine-fuel unit configured to receive fuel from the second fuel tank and deliver the fuel to an engine and the engine-fuel unit is in thermal communication with the cooling loop, and wherein the method further comprises conducting the fluid in the cooling loop to the engine-fuel unit before conducting the fluid to the air-stream heat exchanger to transfer heat between the fluid in the cooling loop and the fuel in the engine-fuel unit.
17 . The method of claim 16 , wherein the engine-fuel unit includes a valve system in fluid communication with the second fuel tank and an engine-fuel heat exchanger in thermal communication with the valve system and the cooling loop to transfer heat between the fluid in the cooling loop and the fuel from the second fuel tank, and wherein the valve system is configured to vary a flow of fuel through the engine-fuel heat exchanger to deliver fuel to the engine at an engine-fuel unit predetermined threshold temperature.
18 . The method of claim 17 , wherein the valve system includes a mix valve, a first conduit in fluid communication between the mix valve and the second fuel tank to deliver fuel having a first temperature to the mix valve, and a second conduit in fluid communication between the mix valve and the second fuel tank, wherein the engine-fuel heat exchanger is in thermal communication with the second conduit to cause the second conduit to deliver fuel having a second temperature to the mix valve, and wherein the mix valve is configured to vary a first flow rate of fuel from the first conduit and a second flow rate of fuel from the second conduit to provide a mixed stream of fuel having a third temperature that is less than or equal to the engine-fuel unit predetermined threshold temperature.
19 . The method of claim 15 , further comprising measuring the heat transfer between the fluid and the fuel in the first fuel tank, comparing the heat transfer measured to a predetermined heat rejection schedule, and selectively varying the flow of fluid in the cooling loop through the fuel-tank heat exchanger in response to the heat transferred measured being different from the predetermined heat rejection schedule.
20 . The method of claim 15 , further comprising measuring the temperature of the fluid in the cooling loop upstream of an accumulator included in the cooling loop, comparing the temperature measured to a sensor target temperature, and selectively varying the flow of fluid in the cooling loop through the air-stream heat exchanger in response to the temperature measured being different from the sensor target temperature.