Method and apparatus for isothermal cooling
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Solution Overview
Problem
Existing cooling systems face challenges in achieving isothermal heat rejection due to poor liquid distribution in evaporator channels, leading to sub-optimal performance and inefficiencies in vapor compression systems.
Innovation Solution
A cooling apparatus that includes a separator vessel, subcooler, flow control valve, primary evaporator assembly, and pressure regulator to maintain refrigerant saturation pressure, ensuring equal liquid distribution and optimal isothermal evaporation conditions by controlling the saturation temperature and providing slightly subcooled flow to evaporators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-phase distributors are used to distribute liquid-vapor mixtures amongst parallel channels, then the system can handle vapor flow, but the liquid distribution becomes unbalanced causing channels with excess liquid and channels with too little liquid
Solution Approach 1:
The patent extracts the vapor phase from the liquid-vapor mixture before distribution by using a flash gas bypass system. The vapor is separated and routed directly to the compressor inlet, while only saturated liquid is distributed to the evaporator channels through dedicated liquid distributors, eliminating the liquid distribution imbalance problem
Solution Approach 2:
The system segments the refrigerant flow path into separate vapor and liquid pathways. The vapor pathway routes flash gas directly to the compressor, while the liquid pathway distributes saturated liquid to evaporator channels, allowing each pathway to be optimized for its specific function without interference
2Area of stationary object
If microchannel evaporators with excessive numbers of channels are used, then the heat transfer surface area increases, but the liquid distribution becomes unwieldy and difficult to control
Solution Approach 1:
The patent removes vapor from the distribution system through a flash gas bypass, ensuring that only liquid flows through the distributors to microchannel evaporators. This simplifies the distribution system by eliminating the complexity of two-phase flow control while maintaining high heat transfer surface area
3Manufacturing precision
If flash gas bypass systems are used to distribute nearly pure saturated liquid, then liquid distribution improves, but any pressure drop causes vapor formation and increases maldistribution
Solution Approach 1:
The system performs preliminary separation of vapor and liquid in a flash tank before distribution. By removing vapor upfront and maintaining proper pressure control through the liquid line, the system prevents vapor formation during distribution, ensuring reliable liquid delivery to all evaporator channels
Solution Approach 2:
The patent incorporates pressure regulation and control mechanisms that monitor and adjust system pressure to prevent vapor formation. The electronic expansion valve and pressure control system provide feedback control to maintain liquid saturation and prevent premature vaporization in the distribution lines
4Adaptability or versatility
If two-phase pumped loops are used to circulate liquid, then the system can handle two-phase flow, but substantial liquid head is required at pump inlet to avoid cavitation
Solution Approach 1:
The patent extracts vapor from the refrigerant flow before it reaches the pump by using a flash gas bypass system. Only liquid is pumped through the system, eliminating cavitation risks and the need for substantial liquid head at the pump inlet while maintaining two-phase flow capability in the evaporators
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 apparatus effectively maintains isothermal evaporation conditions, optimizing liquid distribution and enhancing the performance of vapor compression systems by controlling saturation pressure and subcooling, thereby improving cooling efficiency and reducing maldistribution issues.
Implementation Method 1
a subcooler having a first side in fluid communication with the first fluid flowpath and a second side configured to be disposed in thermal communication with a cold sink
Implementation Method 2
a primary evaporator assembly including at least one primary evaporator configured to be disposed in thermal communication with a primary heat load
Implementation Method 3
absorbing heat from a primary heat load at a predetermined temperature
Implementation Method 4
a pressure regulator operable to maintain a refrigerant saturation pressure within the primary evaporator at a predetermined set point
Implementation Method 5
a separator vessel; a subcooler having a first side in fluid communication with the first fluid flowpath
Data Source
AI summary
A cooling apparatus includes: a first fluid flowpath including the following elements, in downstream flow sequence: a separator vessel; a subcooler having a first side in fluid communication with the first fluid flowpath and a second side configured to be disposed in thermal communication with a cold sink; a flow control valve; a primary evaporator assembly including at least one primary evaporator configured to be disposed in thermal communication with a primary heat load; and a pressure regulator operable to maintain a refrigerant saturation pressure within the primary evaporator at a predetermined set point.