Air-driven vapor cycle refrigeration system

1. A system, comprising:

an air pressurization system (APS) configured to supply pressurized supply air to an environmental control system (ECS), wherein the APS comprises at least one of:

one or more cabin air compressors electrically driven by an auxiliary power unit (APU); or

a load compressor mechanically driven by the APU;

the ECS, comprising:

a primary heat exchanger (PHX) configured to cool the supply air using:

during flight conditions, environmental air supplied via a ram air PHX line; and

during grounded conditions, bay air supplied via a bay air PHX supply line from a bay of the aircraft;

an air-driven turbine downstream of the PHX and configured to power a vapor cycle refrigeration system (VCRS) using the supply air;

a turbine bypass throttle valve and a turbine bypass line configured to bypass at least a portion of the supply air around the air-driven turbine;

the VCRS downstream of the air-driven turbine and configured to cool the supply air to generate cabin air, wherein the VCRS comprises:

an evaporator configured to receive the supply air from the air-driven turbine and cool the supply air using a refrigerant; and

a condenser fluidically coupled to a ram air condenser supply line and configured to cool the refrigerant using the environmental air;

a ram air fan configured to, during the grounded conditions:

draw the environmental air through the condenser supplied via the ram air condenser supply line; and

draw the bay air through the PHX supplied via the bay air PHX supply line; and

a ram air fan line valve configured to close during the flight conditions and open during the grounded conditions; and

a controller configured to control the VCRS using the turbine bypass throttle valve.

2. The system of claim 1 , further comprising a catalytic converter upstream of the PHX and configured to remove hydrocarbon contaminants from the supply air.

3. The system of claim 1 , wherein the VCRS further comprises a vapor cycle compressor (VCC) configured to receive mechanical power from the air-driven turbine through a mechanical link and pump the refrigerant in response to receiving the mechanical power.

4. The system of claim 3 , wherein the mechanical link comprises at least one of a sealed shaft or a hermetically-sealed contactless torque coupling.

5. The system of claim 3 , wherein the controller is configured to control the VCRS using the turbine bypass throttle valve by controlling a speed of the VCC based on at least one of a temperature of the supply air leaving the evaporator or a superheat of the refrigerant entering the VCC.

6. The system of claim 1 , wherein the APS comprises the one or more cabin air compressors.

7. The system of claim 1 , wherein the APS comprises the load compressor.

8. The system of claim 1 , further comprising a water separator downstream of the evaporator and configured to aspirate water using a portion of the supply air.

9. The system of claim 1 , further comprising a cabin recirculation line configured to supply cabin recirculation air to the VCRS.

10. The system of claim 1 , further comprising a PHX bypass valve configured to bypass at least a portion of the supply air around the PHX, wherein the controller is configured to control an inlet temperature of the air-driven turbine using the PHX bypass valve.

11. A method comprising:

supplying, by an air pressurization system (APS) of an aircraft, pressurized supply air to an environmental control system (ECS), wherein the APS comprises at least one of:

one or more cabin air compressors electrically driven by an auxiliary power unit (APU); or

a load compressor mechanically driven by the APU; and

operating the ECS at each of grounded conditions and flight conditions of the aircraft, wherein operating the ECS comprises:

powering, by an air-driven turbine downstream of a primary heat exchanger (PHX) using the supply air, a vapor cycle refrigeration system (VCRS), wherein the ECS comprises a turbine bypass throttle valve and a turbine bypass line configured to bypass at least a portion of the supply air around the air-driven turbine;

cooling, by the VCRS downstream of the air-driven turbine, the supply air to generate cabin air, wherein cooling the supply air includes:

receiving, by an evaporator of the VCRS, the supply air from the air-driven turbine;

cooling, by the evaporator, the supply air using a refrigerant; and

cooling, by a condenser of the VCRS, the refrigerant using environmental air;

cooling, during the flight conditions, both the PHX and the condenser using the environmental air supplied via a ram air supply line;

cooling, during the grounded conditions and using a ram air fan:

the condenser using the environmental air supplied via the ram air condenser supply line; and

the PHX using bay air supplied via a bay air PHX supply line from a bay of the aircraft; and

controlling, by a controller of the ECS, the VCRS using the turbine bypass throttle valve.

12. The method of claim 11 , wherein during operation of the ECS at the grounded conditions:

a temperature of the pressurized supply air is greater than about 200° F., and

wherein a pressure of the pressurized supply air is greater than about 10 psig.

13. The method of claim 11 , wherein during operation of the ECS at the flight conditions:

the aircraft is at greater than about 30,000 feet elevation, and

a pressure of the pressurized supply air is greater than about 3 psig above a pressure of the cabin air.

14. The method of claim 11 , wherein cooling the supply air further comprises:

receiving, by a vapor cycle compressor (VCC), mechanical power from the air-driven turbine through a mechanical link; and

pumping, by the VCC and in response to receiving the mechanical power, the refrigerant.

15. The method of claim 11 , further comprising removing, by a catalytic converter upstream of the PHX, hydrocarbon contaminants from the supply air.