Thermal management systems for extended operation
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Solution Overview
Problem
Conventional refrigeration systems are heavy and power-intensive, making them unsuitable for applications with size and weight constraints, such as mobile platforms, and struggle to maintain precise temperature control for high heat flux, temperature-sensitive loads due to single-phase refrigerant fluid temperature increases during heat absorption.
Innovation Solution
The implementation of an open circuit refrigeration system using a two-phase refrigerant fluid flow path with a gas receiver to maintain refrigerant fluid pressure, allowing for constant-enthalpy expansion and vapor quality control, which stabilizes the temperature of high heat flux loads within a narrow range without the need for compressors or condensers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional closed-circuit refrigeration systems are used, then cooling capacity is achieved, but weight and power consumption increase significantly
Solution Approach 1:
The patent extracts and removes the compressor and condenser components from the refrigeration system, transitioning from a closed-circuit to an open-circuit design. This extraction eliminates the heavy, power-intensive components while retaining the essential cooling function through direct refrigerant evaporation in the evaporator, thereby reducing power consumption and weight while maintaining cooling capability.
Solution Approach 2:
The open-circuit system uses a disposable charge of liquid refrigerant stored in the receiver instead of requiring continuous operation of expensive, power-intensive compressors and condensers. The refrigerant is used once to absorb heat and then exhausted, replacing the need for expensive, high-power mechanical compression and heat rejection components.
2Duration of action of moving object
If open circuit refrigeration systems are designed for extended operation, then operational duration increases, but receiver size and refrigerant charge increase
Solution Approach 1:
The patent changes the thermodynamic parameters of the refrigerant by using a two-phase mixture with controlled vapor quality instead of single-phase liquid. This parameter change allows the system to achieve extended operational duration with a smaller receiver volume, as the phase change process efficiently absorbs heat over time without requiring proportionally larger storage capacity.
Solution Approach 2:
The system utilizes phase transitions of the refrigerant fluid, specifically the transition from liquid to vapor in the evaporator, to provide cooling over extended periods. The controlled vapor quality (two-phase mixture) allows efficient heat absorption during phase change, extending operational duration without requiring a proportionally larger receiver volume.
3Manufacturing precision
If single-phase refrigerant fluid is used for heat absorption, then system simplicity is maintained, but temperature control precision deteriorates due to refrigerant temperature increase
Solution Approach 1:
The patent employs phase transitions of the refrigerant fluid, specifically the liquid-to-vapor transition in the evaporator, to maintain constant temperature during heat absorption. The two-phase mixture with controlled vapor quality ensures that the refrigerant absorbs heat at a constant saturation temperature, preventing temperature increase and enabling precise temperature control for temperature-sensitive loads.
Solution Approach 2:
The system changes the thermodynamic state of the refrigerant from single-phase liquid to two-phase mixture with controlled vapor quality. This parameter change allows the refrigerant to absorb heat at constant temperature through phase change, thereby maintaining precise temperature control while handling high heat flux loads.
4Device complexity
If compressors and condensers are included in the system, then refrigerant circulation is ensured, but system weight and complexity increase
Solution Approach 1:
The patent extracts and removes the compressor and condenser components from the refrigeration system, transitioning to an open-circuit design. This extraction eliminates heavy, complex mechanical components while maintaining essential cooling function through direct refrigerant evaporation, thereby reducing both system weight and complexity.
Solution Approach 2:
The open-circuit system eliminates the need for active refrigerant circulation devices like compressors. Instead, the system uses passive refrigerant expansion and evaporation processes, where the refrigerant self-regulates its phase change and heat absorption without requiring complex mechanical circulation systems, thereby reducing both weight and complexity.
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 reduces the overall size, weight, and power consumption of the refrigeration system while effectively stabilizing the temperature of high heat flux loads, extending operational time and maintaining precise temperature control for temperature-sensitive components.
Implementation Method 1
evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 2
evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 3
a third control device that is configurable to control a flow of the gas from the first receiver to the second receiver to regulate a vapor pressure in the second receiver
Implementation Method 4
The first control device performs a constant-enthalpy expansion of the liquid refrigerant fluid to generate the refrigerant fluid mixture
Implementation Method 5
open circuit refrigeration systems generally include a liquid refrigerant receiver, an expansion device, and a heat absorption exchanger
Implementation Method 6
Refrigeration systems absorb thermal energy from the heat sources operating at temperatures below the temperature of the surrounding environment
Data Source
AI summary
Thermal management systems include an open circuit refrigeration system featuring a first receiver configured to store a gas, a second receiver configured to store a liquid refrigerant fluid, an evaporator configured to extract heat from a heat load that contacts the evaporator, and an exhaust line, where the first receiver, the second receiver, the evaporator, and the exhaust line are connected to provide a refrigerant fluid flow path.