Parallel RAM Heat Exchangers with Compressor Bypass
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Solution Overview
Problem
Current aircraft air conditioning systems require high engine pressures for cabin pressurization and cooling, leading to inefficient fuel burn, and the parallel cooling method through multiple heat exchangers faces issues with windmilling of compressing devices.
Innovation Solution
A system that bleeds a medium from a low-pressure engine location through multiple heat exchangers in parallel, bypassing the compressing device during cooling, and uses mechanisms to prevent windmilling by controlling airflow, such as shutters or motors to maintain device speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high engine pressures are used for cabin pressurization and cooling, then system performance is maintained, but engine fuel efficiency deteriorates
Solution Approach 1:
The system divides the cooling function into multiple parallel heat exchangers instead of using a single high-pressure system. Each heat exchanger operates at lower pressure, and their combined effect provides the required cooling capacity, thereby maintaining performance while reducing the energy penalty of high-pressure operation
Solution Approach 2:
The invention changes the pressure parameter from high to low by bleeding air from a low-pressure location on the engine. This parameter change allows the system to achieve the same cooling effect with significantly reduced engine fuel burn, as the pressure ratio across the heat exchangers is much lower
2Use of energy by moving object
If the compressing device is bypassed during parallel cooling, then fuel efficiency is improved, but windmilling of the compressing device occurs causing wear
Solution Approach 1:
The system takes preliminary action to prevent windmilling by providing a bypass path for the compressing device. When the compressing device is not needed for cooling (during parallel heat exchanger operation), the bypass allows its discharge side to remain connected to the system, preventing pressure differential-induced windmilling and extending component life
Solution Approach 2:
The bypass acts as an intermediary element that mediates between the compressing device and the rest of the system. It provides an alternative flow path that prevents harmful windmilling while allowing the compressing device to be bypassed during operation, thus protecting the device without compromising system function
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 approach reduces engine fuel burn by minimizing pressure drop and energy consumption while preventing wear from windmilling, enhancing the efficiency and reliability of environmental control systems in aircraft.
Implementation Method 1
a plurality of heat exchangers configured to provide parallel cooling by receiving the medium in parallel across at least a first heat exchanger and a second heat exchanger
Data Source
AI summary
A system, which includes a plurality of heat exchangers and a compressing device, is configured to prepare in parallel a medium bled from a low-pressure location of an engine and flowing through a plurality of heat exchangers into a chamber. The compressing device is in communication with the plurality of heat exchangers and regulates a pressure of the medium flowing through the plurality of heat exchangers. The compressing device is bypassed based on the preparing in parallel the medium for the chamber, which in turn enables the compressing device to windmill. Therefore, the system employs at least one mechanism to prevent components of the compressing device from windmilling.