Systems and methods for controlling pumped two-phase refrigerant temperature
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Solution Overview
Problem
Current pumped two-phase refrigerant cooling systems face issues with vapor ingestion by pumps, leading to cavitation and reduced performance due to subcooling requirements, which diminish heat transfer efficiency and cause hot spots and CPU thermal throttling.
Innovation Solution
A system that includes a pump, evaporator, condenser, compressor, and controller to manage refrigerant phase change, minimizing single-phase cooling by controlling the refrigerant's temperature and phase through heating, cooling, and phase separation, ensuring efficient vapor and liquid phase management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerant is subcooled to prevent vapor ingestion and cavitation in the pump, then pump reliability is improved, but heat transfer efficiency deteriorates due to diminished two-phase cooling performance and hot spot formation
Solution Approach 1:
The system performs preliminary heating of the refrigerant in a heater located between the pump and evaporator to ensure the refrigerant enters the evaporator at a temperature that promotes immediate flash evaporation. This preliminary action prevents the refrigerant from being over-subcooled, thereby maintaining pump reliability while preserving heat transfer efficiency by ensuring two-phase cooling occurs effectively in the evaporator
Solution Approach 2:
The system dynamically adjusts the temperature parameter of the refrigerant by controlling the heater operation. By changing the refrigerant temperature from a heavily subcooled state to a near-boiling state before it enters the evaporator, the system resolves the contradiction between preventing cavitation (needing subcooling) and maintaining heat transfer efficiency (needing minimal subcooling)
2Object-affected harmful factors
If the refrigerant is heavily subcooled to ensure pump safety, then cavitation is prevented, but single-phase heat transfer dominates causing CPU thermal throttling and performance loss
Solution Approach 1:
The heater performs a preliminary heating action on the subcooled refrigerant to raise its temperature close to the boiling point before it enters the evaporator. This ensures that when the refrigerant contacts the hot CPU surface, immediate flash evaporation occurs, enabling effective two-phase cooling that prevents CPU thermal throttling while the initial subcooling level remains sufficient to prevent cavitation
Solution Approach 2:
The system applies preliminary anti-action by heating the refrigerant to counteract the excessive subcooling effect. This preliminary heating prevents the harmful outcome of single-phase heat transfer dominance by ensuring the refrigerant is ready to undergo phase change in the evaporator, thereby maintaining CPU performance without compromising cavitation prevention
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 enhances heat transfer efficiency by maintaining optimal refrigerant phase, preventing cavitation, and minimizing single-phase cooling, thereby improving system performance and preventing thermal throttling.
Implementation Method 1
refrigerant within the evaporator can be heated by the heat load, thereby causing at least some of the refrigerant to change from a liquid phase to a vapor phase
Implementation Method 2
the condenser can be configured to cool the refrigerant fluidically downstream from the evaporator, thereby causing at least some of the refrigerant to change from the vapor phase to the liquid phase
Implementation Method 3
a pump configured to pump a refrigerant through an evaporator
Data Source
AI summary
A method can include pumping the refrigerant through an evaporator in thermal communication with a heat load, thereby heating the refrigerant and causing at least some of the refrigerant to change from a liquid phase to a vapor phase, cooling the refrigerant in a condenser fluidically downstream from the evaporator, thereby causing at least some of the refrigerant to change from the vapor phase to the liquid phase, extracting a portion of the refrigerant in the vapor phase fluidically between the evaporator and the condenser, and injecting the extracted portion of the refrigerant, in the vapor phase, fluidically between the pump and the evaporator, thereby increasing the temperature of the refrigerant entering the evaporator to minimize single-phase cooling in the evaporator.