An environmental control system for an aircraft includes a higher pressure tap associated with a higher compression location in a main compressor section. The higher pressure tap leads into a turbine section of a turbocompressor such that air in the higher pressure tap drives the turbine section to in turn drive a compressor section of the turbocompressor. A combined outlet receives airflow from a turbine outlet and a compressor outlet intermixing airflow and passing the mixed airflow downstream to be delivered to an aircraft system. A buffer air outlet communicates airflow to an engine buffer air system.

Cabin outflow temperature control systems and methods for use on aircraft are described. The systems include an aircraft cabin, a heat load source, a heat exchanger configured to receive cabin outflow air from the aircraft cabin and heat load discharge air, the heat exchanger configured to enable thermal transfer from the heat load discharge air to the cabin outflow air to generate high temperature cabin outflow air and low temperature discharge air as outputs from the heat exchanger, and one or more downstream operation systems configured to receive the high temperature cabin outflow air and perform a downstream operation using said high temperature cabin outflow air.

An environmental control system includes a compression device including a compressor, a turbine, and an electric motor operably coupled by a shaft. The electric motor and the turbine are arranged in series relative to a flow of a first medium.

An environmental control system of a vehicle includes a first compression device including a compressor, a first turbine, and a power turbine operably coupled by a shaft. The first turbine is configured to receive a first medium, the compressor is configured to receive a second medium, and the power turbine is configured to receive a third medium. A second compression device, separate from the first compression device, includes a second turbine. The environmental control system is operable in a first mode and a second mode. In the first mode, the second medium is provided to the compressor and the second turbine sequentially. In the second mode, the second medium bypasses the second turbine. In in both the first mode and the second mode, only the second medium is provided to an outlet of the environmental control system.

A shaft for a cabin air compressor includes a first attachment portion, a second attachment portion, an intermediate portion, a retention flange, and a tie rod support pocket. The first attachment portion is disposed at a first end of the shaft. The second attachment portion is disposed at a second end of the shaft opposite the first end. The intermediate portion extends from the first attachment portion to the second attachment portion and an interior wall of the intermediate portion defines an inner shaft space. The retention flange extends a first distance into the inner shaft space from the interior wall of the intermediate portion and is offset from the first attachment portion by a second distance. The tie rod support pocket is defined by the interior wall, extends between the flange and the first attachment portion, and is configured to receive a tie rod support.

Aircraft environmental control systems having electrically powered ram circuit fans are described herein. An example environmental control system includes an air cycle machine to produce cabin air for a cabin of the aircraft. The air cycle machine includes a turbine and a heat exchanger. The environmental control system also includes a ram circuit. The heat exchanger is disposed in the ram circuit. The environmental control system further includes a fan in the ram circuit to control air flow through the ram circuit and across the heat exchanger, an electric motor, and an overrunning clutch operatively coupled between the turbine and the electric motor to enable the turbine to drive the fan during a first mode of operation and to enable the electric motor to drive the fan during a second mode of operation.

An environmental control system (ECS) for an aircraft includes a primary heat exchanger, a compressor including an inlet fluidically connected to the primary heat exchanger, a turbine operatively connected to the compressor, and a cryogenic fluid heat exchanger fluidically connected to the primary heat exchanger.

Aircraft systems including a fuel tank containing a cryogenic fuel, an engine configured to consume the fuel, and an ECS having a precooler arranged to receive the fuel and air from the engine. The precooler includes a first heat exchanger configured to receive a first state of the fuel and output a second state of the fuel and a second heat exchanger configured to receive the second state fuel and output a third state fuel. The first state has a first density, the second state has a second density, and the third state has a third density, wherein the first density is greater than the second density, and the second density is greater than the third density. The engine air is directed through the second heat exchanger first and then through the first heat exchanger.

Vehicles, environmental control systems, and methods for operating an environmental control system are provided. In one example, the environmental control system (ECS) includes an ECS refrigeration unit that is configured to receive ambient air and a first portion and a second portion of hot bleed air. The ECS refrigeration unit is operable to indirectly exchange heat between the first portion of the hot bleed air and the ambient air to form a partially cooled, hot air stream, and to compress, further indirect heat exchange, and expand the partially cooled, hot air stream to form a cooled and expanded air stream. A low limit valve control regulates a low limit valve to control a rate of introduction of the second portion of the hot bleed air to the cooled and expanded air stream to form a combined air stream that when exiting the ECS refrigeration unit is a sub-freezing air stream.

Aircraft systems including a pressurized fuel tank containing a pressurized fuel, a turbo expander configured to receive the pressurized fuel from the fuel tank, the turbo expander configured to decrease a pressure of the pressurized fuel to generate low pressure fuel having pressure less than the pressurized fuel, a fuel-to-air heat exchanger configured to receive the low pressure fuel from the turbo expander as a first working fluid and air as a second working fluid, the heat exchanger configured to cool the air and warm the fuel, an aircraft cabin configured to receive the cooled air, and a fuel consumption system configured to consume the fuel to generate power.