Thermal management systems
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Solution Overview
Problem
Conventional refrigeration systems are heavy and power-intensive, making them impractical for mobile platforms and applications requiring precise temperature control of high heat flux loads, especially when size and weight constraints are a concern.
Innovation Solution
The implementation of open circuit refrigeration systems (OCRSs) that recirculate non-evaporated refrigerant and overfeed the evaporator, reducing the physical dimensions and power consumption of the system by using a pump to indirectly supply liquid to the evaporator, maintaining a set vapor quality of the refrigerant fluid, and employing a back pressure regulator to control vapor pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed-circuit refrigeration systems are used, then reliable temperature control is achieved, but system weight and power consumption increase significantly
Solution Approach 1:
The patent extracts and removes the heavy compressor and condenser components from the refrigeration system, transitioning from a closed-circuit to an open-circuit configuration. This extraction eliminates the need for mechanical compression while maintaining temperature control through evaporative cooling and refrigerant recirculation, directly resolving the contradiction between reliability and weight.
Solution Approach 2:
The patent replaces the mechanical compression system with a chemical/physical phase-change system. Instead of using a mechanical compressor to pressurize refrigerant, the system uses evaporative cooling and pressure regulation valves to control refrigerant phase changes, thereby reducing mechanical complexity and weight while maintaining cooling effectiveness.
2Reliability
If conventional closed-circuit refrigeration systems are used, then temperature control is maintained, but power consumption increases
Solution Approach 1:
The patent extracts the high-power compressor from the system architecture, replacing it with low-power components including a recirculation pump and pressure regulation valve. This extraction dramatically reduces power consumption while maintaining temperature control through passive evaporative cooling and controlled refrigerant dosing.
Solution Approach 2:
The refrigeration system uses the heat load itself to drive the refrigeration cycle. The absorbed thermal energy from the heat load provides the driving force for refrigerant evaporation and circulation, eliminating the need for external high-power compression and reducing overall power consumption.
3Device complexity
If open circuit refrigeration systems without recirculation are used, then system simplicity is achieved, but evaporator efficiency decreases
Solution Approach 1:
The patent implements continuous recirculation of non-evaporated refrigerant from the evaporator outlet back to the inlet through a recirculation pump. This continuous circulation ensures that liquid refrigerant is constantly supplied to the evaporator, maximizing heat transfer efficiency and preventing evaporator dry-out, while adding only moderate system complexity.
Solution Approach 2:
The patent recovers and recirculates the non-evaporated liquid refrigerant that exits the evaporator instead of discarding it. The recirculation pump captures this liquid and returns it to the evaporator inlet, thereby recovering its cooling potential and improving overall evaporator efficiency with minimal additional complexity.
4Duration of action of moving object
If receiver size is increased to extend operation duration, then operating period is extended, but system weight and volume increase
Solution Approach 1:
The recirculation pump continuously circulates liquid refrigerant from the receiver through the evaporator and back to the receiver, creating a closed-loop system that maintains operation without requiring large receiver storage. This continuous circulation allows the same refrigerant to be reused multiple times, extending operation duration while keeping receiver size and weight minimal.
Solution Approach 2:
The system recovers and recirculates refrigerant continuously rather than requiring large storage capacity. By recovering non-evaporated refrigerant and returning it to the evaporator, the system extends its operational duration using a small receiver, thereby avoiding the weight penalty of large refrigerant storage vessels.
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 approach results in a more efficient use of the evaporator's heat transfer surface, reducing the system's size and weight, and minimizing refrigerant exhaustion, while maintaining precise temperature control for high heat flux loads with reduced power consumption.
Implementation Method 1
an evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 2
a pump having an inlet and an outlet, with the outlet of the pump coupled to the liquid side outlet of the liquid separator
Implementation Method 3
a liquid separator having an inlet, a liquid side outlet, and a vapor side outlet
Implementation Method 4
employing a back pressure regulator to control vapor pressure
Implementation Method 5
the second control device is an expansion valve... which expands the liquid refrigerant into a two phase liquid-vapor refrigerant stream
Data Source
AI summary
A thermal management system includes an open circuit refrigeration circuit that has a refrigerant fluid flow path, with the refrigerant fluid flow path including a receiver configured to store a refrigerant fluid, a first control device configured to receive refrigerant from the receiver, a liquid separator, and an evaporator configured to extract heat from a heat load that contacts the evaporator, with the evaporator coupled to the first control device and the liquid separator. The system includes a pump having an inlet and an outlet, with the outlet of the pump coupled to the liquid side outlet of the liquid separator and a second control device that is coupled to an exhaust line, that is coupled to the vapor side outlet of the liquid separator through the second control device. In operation, the evaporator in the open circuit refrigeration circuit would be coupled to a heat load.