Adaptive trans-critical co2 cooling systems for aerospace applications
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Solution Overview
Problem
Current cooling systems for aerospace applications face limitations in efficiency and compactness, particularly at high ambient temperatures, with vapor compression cycles being limited to lower temperatures and gas-based systems being less efficient and bulkier.
Innovation Solution
A cooling system with valve-controlled refrigerant flow paths and dual expansion circuits that operate in trans-critical, sub-critical, or supercritical modes, using CO2 as a refrigerant to manage ambient conditions, and incorporating features like two-stage compression, ejectors, and thermally driven components to optimize performance across a wide range of operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a vapor compression cycle is used, then cooling efficiency is improved through liquid thermal carrying capacity and heat of vaporization, but the system is limited to lower ambient temperature operation
Solution Approach 1:
The system dynamically switches between vapor compression mode (for lower ambient temperatures) and gas-based mode (for high ambient temperatures) using control logic that monitors ambient conditions and refrigerant state, allowing adaptive operation across the full temperature range rather than being fixed to a single cycle mode
Solution Approach 2:
The system changes the thermodynamic parameters of operation by transitioning between two-phase vapor compression cycles and single-phase gas-based cycles, adjusting the refrigerant's phase state and thermodynamic path based on ambient temperature conditions to maintain efficiency across different operating envelopes
2Adaptability or versatility
If a gas-based system is used to accommodate wide ambient conditions, then adaptability is improved, but system mass and bulk increase due to larger components and duct passages
Solution Approach 1:
The cooling system is segmented into two distinct operational modes or subsystems: a vapor compression subsystem for efficient low-temperature operation and a gas-based subsystem for high-temperature operation, with control logic that activates only the necessary subsystem, avoiding the need to carry full gas-based infrastructure at all times
Solution Approach 2:
The refrigerant system serves multiple functions by operating in both two-phase vapor compression mode and single-phase gas-based mode, with the same refrigerant loop and core components handling both operational regimes, eliminating the need for completely separate systems and reducing overall mass
3Adaptability or versatility
If a gas-based system is used, then adaptability to wide ambient conditions is improved, but cooling efficiency decreases due to limited heat capacitance of air
Solution Approach 1:
The system dynamically selects the appropriate thermodynamic cycle based on real-time ambient temperature monitoring and refrigerant state detection, switching from vapor compression mode (higher efficiency) to gas-based mode (lower efficiency) only when ambient conditions exceed the vapor compression operating envelope, thereby maximizing efficiency across the full operational range
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 efficient and compact cooling across a wide range of ambient conditions, reducing mass and bulk while maintaining performance, by dynamically adjusting refrigerant flow and using CO2 to span the range of operating conditions, thereby improving overall system efficiency and adaptability.
Implementation Method 1
an evaporator, a first circuit having an expansion device, a second circuit having an expansion machine
Implementation Method 2
a heat exchanger through which a refrigerant flows, and which rejects heat to a fluid
Implementation Method 3
a first circuit having an expansion device, a second circuit having an expansion machine
Data Source
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AI summary
A cooling system includes a heat exchanger (210) through which a refrigerant flows, and which rejects heat to a fluid, an evaporator (208), a first circuit having an expansion device (214), a second circuit having an expansion machine (202) coupled to a compressor (204), and a set of valves (218) arranged to direct the refrigerant through the first circuit, the second circuit, or both the first and second circuits based on ambient conditions.