Two-Phase Thermal Exchange with Post-Load Mixing Control
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Solution Overview
Problem
Existing thermal control systems face performance limitations due to substantial pressure drops and long transport lines, which can lead to undesired changes in refrigerant state and control characteristics, particularly in semiconductor processing where precise temperature control is required.
Innovation Solution
The Post Load Mixing (PLM) technique involves separating and recombining the high pressure gas phase and cooled, liquefied refrigerant flow after the thermal load, using a compact PLM line box to stabilize the refrigerant's temperature and pressure, reducing pressure drops and enhancing heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If long transport lines are used to deliver refrigerant media, then the system can accommodate geometric considerations and installation flexibility, but pressure drops increase and temperature variations occur leading to control instability
Solution Approach 1:
The refrigerant flow is segmented into separate liquid and vapor paths. The liquid path includes a liquid line with accumulator and liquid line valve, while the vapor path includes a vapor line with vapor sensor and vapor valve. This segmentation allows independent control of each phase, preventing control instability caused by pressure drops in long transport lines.
Solution Approach 2:
An accumulator is introduced as an intermediary device in the liquid line to maintain liquid refrigerant supply stability. The accumulator stores liquid refrigerant and releases it steadily, compensating for pressure variations caused by long transport lines and ensuring reliable liquid supply to the expansion device.
2Productivity
If two-phase medium is used for thermal exchange, then heat transfer efficiency is improved, but phase changes introduce complexity and unpredictability in system control
Solution Approach 1:
The two-phase refrigerant system is divided into separate liquid and vapor flow paths with independent control mechanisms. The liquid line contains an accumulator and liquid line valve for controlling liquid flow, while the vapor line contains a vapor sensor and vapor valve for managing vapor return. This segmentation simplifies control by allowing independent adjustment of each phase rather than managing the complex interplay of a mixed two-phase system.
Solution Approach 2:
A vapor sensor is implemented in the vapor line to provide feedback on vapor refrigerant conditions. This feedback enables the vapor valve to automatically adjust vapor flow to maintain optimal system operation, reducing the complexity of manual two-phase control while preserving high heat transfer efficiency.
3Manufacturing precision
If pressure drops are reduced in the system, then temperature control precision is improved, but this requires shorter transport lines which limits installation flexibility
Solution Approach 1:
The refrigerant distribution system is segmented into dedicated liquid and vapor lines with separate control valves and sensors. This segmentation allows optimization of each line for its specific function, enabling precise temperature control through independent flow regulation while accommodating long transport lines through proper phase separation and control strategies.
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
PLM achieves tighter temperature control and more efficient thermal exchange, reducing temperature differentials from 10° C to 3° C, and prevents unwanted liquefaction and phase variations, even with long transport lines, by maintaining a higher percentage of liquid phase and optimizing heat transfer coefficients.
Implementation Method 1
employs the thermodynamic properties of a refrigerant in both vapor and liquid phases
Implementation Method 2
the refrigerant is converted, by cooling, to liquid phase and the flow is then further cooled by expansion
Implementation Method 3
One flow path maintains the fluid in high pressure gaseous phase
Implementation Method 4
exchange thermal energy with a load so as to maintain the temperature at a selected target level
Implementation Method 5
properly interrelated to exchange thermal energy with a load
Implementation Method 6
a medium is first compressed to a high temperature gaseous state
Implementation Method 7
the flow is then further cooled by expansion
Implementation Method 8
the refrigerant is converted, by cooling, to liquid phase and the flow is then further cooled by expansion
Data Source
AI summary
In a temperature control system using a controlled mix of high temperature pressurized gas and a cooled vapor/liquid flow of the same medium to cool a thermal load to a target temperature in a high energy environment, particular advantages are obtained in precision and efficiency by passing at least a substantial percentage of the cooled vapor/liquid flow through the thermal load directly, and thereafter mixing the output with a portion of the pressurized gas flow. This “post load mixing” approach increases the thermal transfer coefficient, improves control and facilities target temperature change. Ad added mixing between the cooled expanded flow and a lesser flow of pressurized gas also is used prior to the input to the thermal load. A further feature, termed a remote “Line Box”, enables transport of the separate flows of the two phase medium through a substantial spacing from pressurizing and condensing units without undesired liquefaction in the transport lines.