Aircraft Ground AC Pressure and Refrigerant Flow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing air conditioning units for aircraft parked on the ground lack adaptability to environmental parameters and the unique airflow/pressure curves of different aircraft sizes, leading to inefficient refrigeration and the need for multiple units, which is costly and impractical.
Innovation Solution
The air conditioning unit features multiple parallel refrigerant circuits with individual expansion valves, temperature and pressure sensors to regulate refrigerant flow, and a main fan with adjustable speed to match the specific airflow and pressure requirements of various aircraft, allowing for flexible refrigeration power adjustment and efficient operation across a range of aircraft sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigeration power is fixed in existing air conditioning units, then the unit can operate reliably at its design point, but it cannot adapt to variations in environmental parameters and different aircraft sizes
Solution Approach 1:
The refrigerant circuit is divided into multiple parallel circuits, each with its own expansion valve. This segmentation allows independent control of refrigerant flow to different evaporator sections, enabling continuous adjustment of refrigeration capacity to match varying cooling demands of different aircraft sizes and environmental conditions.
Solution Approach 2:
The system employs dynamic control elements including variable speed compressor, electronically controlled expansion valves, and adjustable fan speed. These dynamic components allow the refrigeration system to continuously adapt its capacity in real-time based on feedback from temperature and pressure sensors, resolving the contradiction between fixed design and variable operational requirements.
2Adaptability or versatility
If the air conditioning unit is designed for large aircraft with high flow rate requirements, then it can serve large aircraft, but it causes overpressure and potential damage when connected to small aircraft
Solution Approach 1:
Pressure sensors are installed in the air outlet circuit to provide real-time feedback on the pressure conditions. This feedback is fed to the control system which automatically adjusts the compressor speed and expansion valve positions to maintain pressure within safe limits, preventing overpressure damage to small aircraft while maintaining adequate cooling capacity for large aircraft.
Solution Approach 2:
The system changes operating parameters dynamically by adjusting compressor discharge pressure, refrigerant flow rate, and fan speed based on the connected aircraft's characteristics. This parameter adjustment allows the same unit to safely serve both small and large aircraft by matching output parameters to the specific aircraft's airflow/pressure curve requirements.
3Ease of operation
If the refrigeration capacity is regulated by alternating between full power and zero power positions, then the system is simple to control, but the refrigeration efficiency is poor and cannot maintain adequate temperature
Solution Approach 1:
Instead of alternating between full and zero power positions, the system applies partial action by using multiple expansion valves to deliver precisely the amount of refrigeration needed. The variable speed compressor and electronic expansion valves enable the system to operate continuously at optimal partial load conditions, maintaining efficiency while providing smooth temperature control.
Solution Approach 2:
The control system transitions from static on/off control to dynamic continuous control using variable speed compressor and electronically controlled expansion valves. This dynamic control maintains the refrigeration system operating points near the optimal efficiency region across varying load conditions, eliminating the energy waste associated with cycling between full and zero power.
4Adaptability or versatility
If manual adjustments are made to regulate refrigeration capacity, then the system can adapt to different conditions, but the operation becomes complex and time-consuming
Solution Approach 1:
The system employs self-regulating control where temperature and pressure sensors automatically monitor operating conditions and adjust refrigerant flow and compressor speed without operator intervention. The microprocessor-based control system autonomously manages the multiple expansion valves and compressor variable speed drive, providing adaptability to different aircraft and environmental conditions while eliminating complex manual adjustments.
Solution Approach 2:
Automatic feedback control loops continuously monitor temperature at the air outlet and pressure in the refrigerant circuit, comparing these measurements with desired setpoints and automatically adjusting expansion valve positions and compressor speed. This closed-loop feedback system provides both adaptability and ease of operation by eliminating manual regulation while maintaining optimal performance.
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 solution enables the same air conditioning unit to effectively cool a variety of aircraft sizes without manual adjustments, maintaining efficiency and preventing damage from overpressure, while reducing the need for multiple units and associated costs.
Implementation Method 1
said ambient air passes through an exchanger-evaporator, where it is cooled by evaporation of a flow of refrigerant circulating in the exchanger-evaporator
Implementation Method 2
an exchanger-evaporator placed in said air circuit to cool the air by evaporating the refrigerant
Implementation Method 3
said refrigerant is compressed in a compressor downstream of the exchanger-evaporator
Implementation Method 4
said refrigerant is condensed in a condenser downstream of the compressor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an air-conditioning unit (1) comprising an air circuit with an air inlet (5), a main fan (10) and an air outlet (6) designed to be connected to a chamber such as, for example, an aircraft parked on the ground, preferably via one or more flexible ducts, and a refrigerant circuit comprising a heat exchanger/evaporator (12) positioned in said air circuit to cool the air by evaporating the refrigerant, a compressor (17) and a condenser (18) for condensing the refrigerant before it is returned to the heat exchanger/evaporator (12). Said heat exchanger/evaporator (12) comprises several parallel circuits (19) each having at least one regulator valve (20). Said air circuit also comprises a temperature probe ST3 downstream of the heat exchanger/evaporator (12) and connected to means of controlling said regulator valves (20) to regulate the flow of refrigerant so as to keep the air temperature downstream of the heat exchanger/evaporator (12) within a reference range, and a pressure probe SP1 at the air outlet (6) and connected to means of regulating the speed and/or the power of the main fan (10) so as not to exceed a maximum raised pressure at the air outlet (6). Said refrigerant circuit also comprises a pressure probe SP3 on the intake side of the compressor (17) and connected to means for regulating the mass flow rate of refrigerant drawn in by the compressor (17) so as to keep the intake pressure of the compressor (17) in a reference range. The present invention also relates to an air-conditioning method.