Aircraft Air Conditioning Flow Control for Minimum Fuel Burn
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Solution Overview
Problem
Current aircraft air conditioning systems face a trade-off where reducing process air mass flow to minimize fuel consumption leads to increased ambient air mass flow, which in turn increases fuel consumption due to increased aerodynamic drag from larger ram air duct openings, necessitating a method to optimize fuel consumption across varying operating conditions.
Innovation Solution
Establishing a correlation between process air and ambient air mass flows and fuel consumption, using an electronic control unit to adjust these flows based on predetermined cooling capacity requirements, minimizing fuel consumption by optimizing both variables simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If process air mass flow is reduced to minimize fuel consumption, then fuel consumption decreases, but ambient air mass flow must be increased to maintain cooling capacity, which increases aerodynamic drag and fuel consumption
Solution Approach 1:
The patent implements dynamic control of both process air mass flow and ambient air mass flow based on real-time operating conditions. The electronic control unit continuously adjusts the ratio between these two air flows to maintain optimal cooling efficiency while minimizing total air flow and aerodynamic drag, rather than using fixed flow rates
Solution Approach 2:
The system changes the parameters of air flow control by establishing correlations between different air flow ratios and fuel consumption values. The electronic control unit selects optimal operating points from pre-calculated pairs of process air mass flow and ambient air mass flow values that correspond to minimum fuel consumption for given cooling capacities
2Use of energy by moving object
If process air mass flow is reduced to minimize fuel consumption, then fuel consumption decreases, but the cooling capacity must be maintained, requiring increased ambient air flow
Solution Approach 1:
The system dynamically balances process air and ambient air flows based on real-time cooling requirements. The electronic control unit continuously monitors cooling capacity demands and adjusts the proportion of ambient air used for cooling versus the proportion of conditioned process air recirculated, optimizing the trade-off between fuel consumption and cooling effectiveness
Solution Approach 2:
The electronic control unit uses feedback from temperature sensors and flow measurements to monitor actual cooling performance. Based on this feedback, the system adjusts the air flow ratios to maintain the required cooling capacity while operating at optimal fuel consumption points, correcting deviations in real-time
3Power
If ambient air mass flow is increased to maintain cooling capacity with reduced process air flow, then cooling capacity is maintained, but aerodynamic drag increases
Solution Approach 1:
The system implements dynamic optimization of ambient air flow rates based on the actual cooling load and process air availability. Rather than using high ambient air flow rates continuously, the electronic control unit adjusts the ambient air flow to the minimum necessary to maintain cooling capacity, reducing aerodynamic drag when high cooling capacity is not required
Solution Approach 2:
The patent changes the operating parameters of the air conditioning system by selecting from pre-calculated pairs of process air mass flow and ambient air mass flow values. Each pair corresponds to a specific cooling capacity and represents an optimal operating point that minimizes the sum of fuel consumption and aerodynamic drag effects
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 allows for reduced fuel consumption in all aircraft air conditioning system operating states by integrating control logic into existing systems, avoiding additional weight and costs, while maintaining optimal cabin comfort and cooling capacity.
Implementation Method 1
In the heat exchanger unit of the air conditioning unit, which may comprise a plurality of heat exchangers, the hot process air which is supplied to the heat exchanger unit is cooled through the transfer of thermal energy to cold aircraft ambient air flowing through the heat exchanger unit.
Implementation Method 2
The process air, which is supplied at a high temperature and under high pressure, is treated in the air conditioning unit upon flowing through a heat exchanger unit as well as a compression and expansion unit such that it leaves the compression and expansion unit as expanded and cooled process air.
Data Source
AI summary
In a method for controlling an aircraft air conditioning system, a correlation is established between a plurality of values of a process air mass flow supplied to an air conditioning unit of the aircraft air conditioning system and the fuel consumption of the aircraft. A correlation is also established between a plurality of values of an ambient air mass flow which is used to cool the process air mass flow supplied to the air conditioning unit of the aircraft air conditioning system and the fuel consumption of the aircraft. The process air mass flow and the ambient air mass flow are controlled in dependence on a predetermined cooling capacity of the aircraft air conditioning system such that the fuel consumption of the aircraft is minimized.