Multi-evaporator trans-critical cooling systems
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Solution Overview
Problem
Aircraft cooling systems face inefficiencies due to significant throttling losses and thermodynamic losses from back pressure regulators in transcritical operations, limiting their ability to maintain effective cooling across varying ambient conditions.
Innovation Solution
A multi-evaporator cooling system with a compressor circuit generating multiple levels of evaporating pressures, utilizing a heat exchanger and multiple compressors to manage refrigerant pressures and temperatures, and incorporating non-isenthalpic expansion to reduce throttling losses, allowing for efficient cooling across different heat loads within an aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If back pressure regulators are installed downstream of each evaporator to maintain different evaporating pressures, then multi-temperature cooling is achieved, but significant throttling losses occur resulting in thermodynamic loss and reduced cooling performance
Solution Approach 1:
The patent removes the back pressure regulator component from the system entirely. Instead of using traditional isenthalpic expansion devices, the invention extracts this function by allowing the evaporators to operate at different pressures naturally through their respective heat loads and refrigerant circulation patterns, eliminating the throttling losses associated with back pressure regulators.
Solution Approach 2:
The system changes the operating parameters by allowing each evaporator to operate at its optimal evaporating pressure and temperature independently, determined by its specific heat load requirements rather than being constrained by isenthalpic expansion through back pressure regulators. This enables non-isenthalpic expansion and reduces thermodynamic losses.
2Adaptability or versatility
If a gas-based cooling system is used to cover the wide range of ambient operating conditions, then system adaptability is improved, but system bulk and efficiency deteriorate
Solution Approach 1:
The patent implements a dynamic system where the refrigerant circulation and heat exchange processes automatically adapt to varying ambient conditions and heat loads. The system uses multiple evaporators operating at different pressures and temperatures, with refrigerant flow dynamically adjusted through the compressors and heat exchangers to match actual cooling demands, eliminating the need for oversized gas-based equipment.
Solution Approach 2:
The system changes operating parameters by allowing each evaporator to operate at its optimal evaporating pressure and temperature independently, determined by its specific heat load requirements. This enables the system to efficiently cover a wide range of ambient conditions without the bulk and inefficiency of traditional gas-based systems.
3Temperature
If multiple evaporators operate at significantly different evaporating pressures, then specific cooling temperatures are achieved, but back pressure regulators are required downstream of each evaporator leading to throttling losses
Solution Approach 1:
The patent removes the back pressure regulator component from the system entirely. Instead of using traditional isenthalpic expansion devices, the invention extracts this function by allowing the evaporators to operate at different pressures naturally through their respective heat loads and refrigerant circulation patterns, eliminating the throttling losses associated with back pressure regulators.
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
The system achieves improved cooling efficiency by tailoring mass flow rates and compressor operations to specific heat loads, reducing thermodynamic losses and enhancing overall cooling performance across a range of ambient conditions.
Implementation Method 1
a heat exchanger configured to receive the compressed refrigerant from the at least one compressor and cool the compressed refrigerant
Implementation Method 2
a first evaporator circuit configured to receive the compressed refrigerant from the heat exchanger, expand the compressed refrigerant to a second pressure that is lower than the first pressure
Implementation Method 3
expand the compressed refrigerant to a second pressure that is lower than the first pressure, and return the refrigerant to the compressor circuit
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A multi-evaporator cooling system (200) includes a compressor circuit (204) that generates multiple levels of evaporating pressures, the circuit (204) comprising at least one compressor (220, 222, 224) configured to compress a refrigerant to a first pressure, a heat exchanger (202) configured to receive the compressed refrigerant from the at least one compressor (220, 222, 224) and cool the compressed refrigerant, a first evaporator circuit (206) configured to receive the compressed refrigerant from the heat exchanger (202), expand the compressed refrigerant to a second pressure that is lower than the first pressure, and return the refrigerant to the compressor circuit (204), and a second evaporator circuit (208) configured to receive the compressed refrigerant from the heat exchanger (202), expand the compressed refrigerant to a third pressure that is lower than the second pressure, and return the refrigerant to the compressor circuit (204).