Thermal management systems
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Solution Overview
Problem
Conventional closed-circuit refrigeration systems are heavy, power-intensive, and unsuitable for mobile platforms due to size and weight constraints, and struggle with maintaining precise temperature control for high heat flux, temperature-sensitive loads.
Innovation Solution
The implementation of open circuit refrigeration systems (OCRSs) with a pump that recirculates non-evaporated refrigerant, utilizing a recuperative heat exchanger to reduce refrigerant mass flow rate demand and a liquid separator to minimize cavitation, allowing for efficient heat transfer and reduced system size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed-circuit refrigeration systems are used, then reliable cooling function is achieved, but system 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 configuration. This extraction eliminates the heavy mechanical compression equipment while maintaining cooling functionality through direct liquid refrigerant evaporation and pump-based circulation, thereby significantly reducing system weight.
Solution Approach 2:
The patent replaces the mechanical compression system with a pump-based liquid circulation system. Instead of using a mechanical compressor to pressurize refrigerant vapor, the system uses a liquid pump to circulate liquid refrigerant directly to the evaporator, where it evaporates to provide cooling. This substitution dramatically reduces mechanical complexity and weight.
2Productivity
If conventional closed-circuit refrigeration systems are used, then cooling capacity is achieved, but power consumption increases
Solution Approach 1:
The patent replaces the high-power mechanical compressor with a low-power liquid pump. The pump circulates liquid refrigerant through the evaporator where evaporation provides the cooling effect. This substitution reduces power consumption significantly because pumping liquid requires much less energy than compressing vapor, while maintaining the same cooling capacity through efficient heat transfer.
Solution Approach 2:
The patent utilizes the phase transition of refrigerant from liquid to vapor in the evaporator as the primary cooling mechanism. The liquid refrigerant absorbs heat from the load during evaporation, providing efficient cooling capacity. This phase change process is highly effective at transferring thermal energy without requiring high-power mechanical compression.
3Duration of action of moving object
If receiver size is increased to extend operation period, then operational duration is improved, but system volume and weight increase
Solution Approach 1:
The patent implements continuous operation by recirculating non-evaporated liquid refrigerant from the evaporator outlet back to the inlet through a pump. This creates a continuous circulation loop that maintains steady cooling operation without requiring large receiver storage, as the system continuously reuses the same refrigerant charge rather than depleting stored refrigerant.
Solution Approach 2:
The patent recovers and recirculates non-evaporated liquid refrigerant that exits the evaporator. Instead of discarding this refrigerant or requiring additional storage, the system uses a pump to return the liquid refrigerant to the evaporator inlet, where it can evaporate again. This recovery and reuse extends operational duration without increasing receiver size.
4Volume of stationary object
If evaporator surface area is reduced, then system size is decreased, but heat transfer efficiency deteriorates
Solution Approach 1:
The patent changes the physical state parameter of the refrigerant from vapor-phase (in conventional systems) to liquid-phase circulation through the evaporator. By pumping liquid refrigerant through the evaporator and allowing it to evaporate, the system achieves higher heat transfer coefficients compared to vapor-based systems. This parameter change enables reduced evaporator surface area while maintaining heat transfer efficiency.
Solution Approach 2:
The patent uses hydraulic principles by circulating liquid refrigerant through the evaporator under pump pressure. The liquid phase provides superior heat transfer characteristics compared to vapor, allowing efficient heat extraction from the load with a more compact evaporator design. The liquid circulation system enables higher heat flux densities on the evaporator surface.
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 enables efficient cooling of high heat flux loads with precise temperature control, reducing system size, weight, and power consumption while maintaining temperature stability within narrow ranges, making it suitable for mobile and temperature-sensitive applications.
Implementation Method 1
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 2
a recuperative heat exchanger that has a first fluid path that receives the refrigerant fluid from the receiver and a second fluid path that provides thermal contact between refrigerant leaving the receiver through an outlet and refrigerant vapor passed into the recuperative heat exchanger from the liquid separator
Implementation Method 3
an evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 4
an evaporator configured to extract heat from a heat load that contacts the evaporator
Implementation Method 5
a liquid separator having an inlet, a liquid side outlet, and a vapor side outlet
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.