Aircraft air conditioning system and method for operating such an aircraft air conditioning system
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Solution Overview
Problem
Current aircraft air conditioning systems are inefficient in terms of energy usage and may lead to icing risks due to operation at low refrigerant temperatures, and they often rely on bleed air from engines, which increases fuel consumption.
Innovation Solution
The system incorporates a refrigerant circuit that thermally couples both ambient and recirculation air lines, allowing for efficient cooling of recirculation air to the same temperature as ambient air, using a two-phase refrigerant and a refrigerant compressor driven by electric motors, and includes a control apparatus to manage air flow through multiple sections of the air line with compressors and bypasses for flexible operation, potentially using a cold air process for dehumidification and heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If bleed air from engines is used to drive compressors, then air conditioning function is achieved, but fuel consumption increases
Solution Approach 1:
The ambient air compressors are designed to serve multiple functions: they provide pressurized ambient air for the refrigeration cycle while also serving as the primary source of fresh air for the cabin. This eliminates the need to use bleed air from engines for driving compressors, thereby reducing fuel consumption while maintaining air conditioning functionality.
Solution Approach 2:
The system uses electric motors to drive ambient air compressors that independently compress ambient air for both refrigeration and cabin pressurization purposes. This self-service approach eliminates dependency on engine bleed air, allowing the air conditioning system to operate independently of engine power extraction.
2Temperature
If refrigerating machine operates at low temperatures, then cooling efficiency improves, but icing risk increases
Solution Approach 1:
The system extracts and removes moisture from the ambient air stream before it enters the refrigeration cycle through a moisture separator. By removing the moisture source beforehand, the refrigeration system can operate at low temperatures without the harmful effect of icing, as there is no free moisture available to freeze in the refrigerant circuit or heat exchangers.
Solution Approach 2:
The moisture separator performs preliminary dehumidification of the ambient air before it reaches the refrigeration components. This preliminary action prevents moisture from entering the low-temperature zones where it could cause icing, allowing the refrigerating machine to operate efficiently at low temperatures without the harmful icing effect.
3Temperature
If recirculation air is cooled to desired temperature, then cabin temperature control improves, but energy consumption increases
Solution Approach 1:
The system merges the cooling of recirculation air with the cooling of ambient air by using a common refrigeration cycle. The refrigerant circuit cools both ambient air (for dehumidification) and recirculation air (for temperature control) in an integrated manner, eliminating the need for separate cooling systems and reducing overall energy consumption while maintaining precise cabin temperature control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables energy-efficient operation, reduces the risk of icing, minimizes fuel consumption by decoupling energy and fresh air feeds, and allows for flexible adaptation to various flight phases, ensuring efficient air conditioning and dehumidification while optimizing energy use.
Implementation Method 1
a refrigerant circuit which is configured to have a refrigerant flow therethrough and which is thermally coupled to the ambient air line in order to transmit heat from the ambient air flowing through the ambient air line to the refrigerant circulating in the refrigerant circuit
Implementation Method 2
thermally coupled to the ambient air line in order to transmit heat from the ambient air flowing through the ambient air line to the refrigerant circulating in the refrigerant circuit
Implementation Method 3
The refrigerant circulating in the refrigerant circuit of the refrigerating machine is preferably a two-phase refrigerant which is transferred from the liquid into the gaseous state of aggregation on absorbing heat from the ambient air flowing through the ambient air line
Implementation Method 4
transferred from the liquid into the gaseous state of aggregation on absorbing heat from the ambient air flowing through the ambient air line
Implementation Method 5
a first ambient air compressor arranged in a first section of the ambient air line for compressing ambient air flowing through the first section of the ambient air line
Implementation Method 6
a turbine arranged in a fourth section of the ambient air line for depressurizing ambient air flowing through the fourth section of the ambient air line
Data Source
AI summary
An aircraft air conditioning system includes an ambient air line configured to have ambient air flow therethrough and being connected to a mixer of the air conditioning system to feed ambient air to the mixer, and a recirculation air line configured to have recirculation air flow therethrough and being connected to the mixer to feed to the mixer recirculation air discharged from an aircraft area to be air conditioned. A refrigerating machine of the air conditioning system includes a refrigerant circuit configured to have a refrigerant flow therethrough and being thermally coupled to the ambient air line and to the recirculation air line to transmit heat from the ambient air flowing through the ambient air line and from the recirculation air flowing through the recirculation air line to the refrigerant circulating in the refrigerant circuit, before the ambient air and the recirculation air are fed into the mixer.