Parallel Ram Heat Exchanger Recirculation System

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Solution Overview

Problem

Current aircraft air conditioning systems require high engine pressures for cabin pressurization and cooling, leading to inefficient engine fuel burn due to the reliance on high-pressure air bleeds.

Innovation Solution

A system that utilizes a medium bled from a low-pressure engine location, flowing through heat exchangers in parallel to reduce temperature and pressure, with a compressing device bypassed to maintain efficient fuel burn, incorporating recirculation and ram air cooling to supply pressurized air to the cabin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-pressure air bleed is used from the engine, then cabin pressurization and cooling is achieved, but engine fuel burn efficiency deteriorates

Engineering Contradiction:
Improvecabin pressurization and coolingVSAvoidengine fuel burn
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The system divides the air flow into multiple parallel paths through a plurality of heat exchangers, allowing the medium to be cooled incrementally at different stages rather than requiring a single high-pressure extraction point

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the pressure parameter by bleeding air from a low-pressure location of the engine instead of a high-pressure location, and uses variable geometry to control the flow distribution across parallel heat exchanger paths to achieve desired cooling at lower pressure ratios

Inventive Principle:
Principle #35Parameter changes

2Temperature

If medium flows through heat exchangers in parallel, then temperature reduction efficiency is improved, but system complexity increases

Engineering Contradiction:
Improvetemperature reduction efficiencyVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cooling function is segmented into multiple parallel heat exchanger units, each handling a portion of the medium flow, which distributes the thermal load and improves overall temperature reduction efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The parallel heat exchanger configuration serves multiple functions simultaneously: cooling the medium, managing pressure distribution, and providing redundant cooling paths, thereby improving temperature efficiency without proportionally increasing complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 using lower initial pressures while maintaining effective cabin pressurization and cooling, achieving high efficiency in environmental control systems for aircraft.

Implementation Method 1

a first temperature of the medium at the valve being reduced when the medium flows across the first heat exchanger and the second heat exchanger in parallel to a second temperature

Methodology Applied
Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

a recirculation bleed line fluidly coupled between the chamber and the inlet line

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP3103721B1Recirculation system for parallel ram heat exchangers
Publication Date: 2021.01.20 HAMILTON SUNDSTRAND CORP
  • EP3103721B1 patent drawingFigure 1
  • EP3103721B1 patent drawingFigure 2
  • EP3103721B1 patent drawingFigure 3

AI summary

A system includes an inlet line (102) configured to receive a medium flowing from a low-pressure location of an engine to a chamber (104), a plurality of heat exchangers (110,120) configured to receive the medium from the inlet line (102), and a valve (106) located upstream from the plurality of heat exchangers (110,120). The valve (106) is configured to divide in parallel the medium across at least a first heat exchanger (110) and a second heat exchanger (120) of the plurality of heat exchangers. A recirculation air system (400) is configured to supply a recirculation air from the chamber (104) to the inlet line (102) upstream of the heat exchangers (110,120).