Adaptive CO2 Cooling Circuit Switching for Wide Ambient Conditions
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Solution Overview
Problem
Current cooling systems for aerospace applications are limited by their efficiency and bulkiness, particularly at high ambient temperatures, with vapor compression cycles being inefficient at lower temperatures and gas-based systems being less efficient and larger in size.
Innovation Solution
A cooling system with valve-controlled refrigerant flow paths that operate in trans-critical, sub-critical, or supercritical modes, using CO2 as a refrigerant and incorporating a heat exchanger, evaporator, expansion devices, and a compressor, allowing for efficient heat rejection and absorption across a wide range of ambient 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 at lower ambient temperatures, but the system becomes less effective at high ambient temperatures
Solution Approach 1:
The system dynamically switches between vapor compression mode and gas-based mode depending on ambient temperature conditions. A controller monitors ambient temperature and automatically selects the appropriate cooling mode, allowing the system to adapt to varying environmental conditions rather than being fixed in a single operating mode.
Solution Approach 2:
The cooling system is designed to perform multiple functions by incorporating both vapor compression and gas-based cooling capabilities within a single integrated system. This multi-functionality allows the system to handle both low-temperature and high-temperature ambient conditions effectively, eliminating the need for separate cooling systems for different temperature ranges.
2Adaptability or versatility
If a gas-based system is used to accommodate wide ambient conditions, then adaptability is improved, but system size and mass increase
Solution Approach 1:
The cooling system is segmented into two distinct cooling modes: vapor compression mode for low-temperature conditions and gas-based mode for high-temperature conditions. Each mode uses only the components necessary for its specific operating range, allowing the system to achieve wide ambient adaptability while minimizing the mass required for each individual mode.
Solution Approach 2:
The system uses dynamic mode selection based on ambient temperature to activate only the necessary cooling pathway. When ambient temperature is low, the vapor compression mode is activated; when ambient temperature is high, the gas-based mode is activated. This dynamic operation reduces the effective mass that needs to be managed at any given time compared to having both systems continuously operational.
3Device complexity
If a gas-based system is used, then system simplicity is improved, but cooling efficiency decreases
Solution Approach 1:
The system dynamically selects between vapor compression mode (higher efficiency) for low-temperature conditions and gas-based mode (lower efficiency but simpler operation) for high-temperature conditions. This dynamic selection optimizes the balance between efficiency and simplicity based on environmental conditions, using the more efficient vapor compression cycle when it provides the greatest benefit.
Solution Approach 2:
The system changes its operating parameters by switching between two distinct cooling modes. The vapor compression mode utilizes phase change parameters (liquid-vapor transition) to achieve high efficiency, while the gas-based mode operates in single-phase conditions with simpler parameters. The controller adjusts which parameter set is active based on ambient temperature thresholds.
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 cooling across varying ambient conditions by selectively directing refrigerant flow through different circuits based on temperature and pressure, optimizing performance and reducing system size and mass.
Implementation Method 1
a heat exchanger through which a refrigerant flows, and which rejects heat to a fluid
Implementation Method 2
an evaporator, a first circuit having an expansion device
Implementation Method 3
a first circuit having an expansion device, a second circuit having an expansion machine
Implementation Method 4
a set of valves arranged to direct the refrigerant through the first circuit, the second circuit, or both the first and second circuits based on ambient conditions
Data Source
AI summary
A cooling system includes a heat exchanger through which a refrigerant flows, and which rejects heat to a fluid, an evaporator, a first circuit having an expansion device, a second circuit having an expansion machine coupled to a compressor, and a set of valves arranged to direct the refrigerant through the first circuit, the second circuit, or both the first and second circuits based on ambient conditions.