Aircraft Cabin Recirculation Control for Rapid Ground Cooling
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Solution Overview
Problem
Current aircraft cabin air-conditioning systems with two recirculation systems face inefficiencies, particularly on hot days when the aircraft is on the ground, leading to increased cooling times and higher fuel and maintenance costs due to additional heat loads from recirculation fans, which slow down cabin cooling and extend turnaround times.
Innovation Solution
A system with a control device that adjusts the air volume flow of the second recirculation system to reduce waste heat input by controlling the air volume flow removed from the second aircraft cabin region, allowing for more efficient utilization of cold fresh air and redistributing recirculation air between systems to maintain sufficient ventilation and cooling capacity without adding weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If both recirculation systems operate at minimum required air flow to ensure sufficient ventilation, then cabin ventilation is maintained, but additional heat load from recirculation fan waste heat increases, reducing cooling capacity for the cabin
Solution Approach 1:
The control device dynamically adjusts the air flow of the second recirculation system based on operating conditions. During normal operation, the second recirculation system operates at minimum required air flow to maintain ventilation. During rapid cooling phases, the control device increases the air flow of the first recirculation system and reduces the second recirculation system, optimizing the balance between ventilation and cooling capacity utilization.
2Reliability
If recirculation systems are operated continuously to maintain air exchange, then cabin air quality is maintained, but waste heat from recirculation fans increases heat load and extends cooling time on hot days
Solution Approach 1:
The system dynamically redistributes air flow between the first and second recirculation systems based on real-time operating conditions. During rapid cooling phases, the control device increases the first recirculation system air flow (which feeds directly into the central mixer with cold fresh air) and reduces the second recirculation system, thereby reducing waste heat generation while maintaining adequate air exchange and accelerating cabin cooling.
Solution Approach 2:
The control device changes the operating parameters (air flow rates) of the recirculation systems based on predefined parameters such as cabin temperature, outside temperature, and cooling requirements. By adjusting these parameters dynamically, the system optimizes the balance between maintaining cabin air quality and reducing heat load during cooling operations.
3Temperature
If air conditioning system run-up period is extended to cool the cabin sufficiently on hot days, then cabin cooling is achieved, but turnaround time at the airport is slowed down and fuel consumption increases
Solution Approach 1:
The control device enables dynamic optimization of the air conditioning system operation during ground-based cooling phases. By increasing the air flow of the first recirculation system during rapid cooling phases, the system accelerates cabin cooling without requiring extended run-up periods, thereby reducing turnaround time and fuel consumption while maintaining effective cabin cooling.
4Reliability
If the second recirculation system operates at high air flow to maintain air exchange in the upper deck region, then ventilation is improved, but waste heat from the recirculation fan increases the heat load on the air conditioning system
Solution Approach 1:
The control device dynamically adjusts the air flow of the second recirculation system based on the operational phase. During normal operation, the second recirculation system operates at minimum required air flow to maintain adequate ventilation. During rapid cooling phases, the control device further reduces the second recirculation system air flow and increases the first recirculation system air flow, thereby minimizing waste heat generation while maintaining sufficient air exchange in the upper deck region.
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 enables rapid cabin cooling, reduces fuel consumption and maintenance costs, and shortens aircraft turnaround times by optimizing cooling capacity and minimizing the impact of recirculation fan waste heat on the air-conditioning system's efficiency.
Implementation Method 1
an air conditioning unit (14) connected to a central mixer (16) in order to supply the central mixer (16) with air at a desired low temperature
Implementation Method 2
The mixed air produced in the mixer and composed of cold fresh air provided by the air conditioning packs and of recirculation air sucked from the aircraft cabin
Implementation Method 3
The recirculation air removed from the middle deck region of the cabin by the high-pressure recirculation system
Implementation Method 4
the waste heat produced by the fans of the recirculation systems gives rise to additional heat loads
Data Source
AI summary
A system for air-conditioning an aircraft cabin includes an air conditioning unit connected to a central mixer, a first recirculation system designed to remove exhaust air from a first aircraft cabin region and connected to the central mixer, and a second recirculation system designed to remove exhaust air from a second aircraft cabin region and connected to a local mixer. A control device is designed to control the second recirculation system to reduce an air volume flow being removed from the second aircraft cabin region when shifting from a first operating state (e.g., normal operation) to a second operating state (e.g., defined operating situations such as when quick cooling is desired). The air volume being removed from the first aircraft cabin region may be increased accordingly in the second operating state.