Two-Phase Refrigerant Post-Load Mixing for Pressure Drop 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) approach, where the cooled expanded flow of a refrigerant is primarily propagated through the thermal load, with a modulated high pressure gas flow combined before and after the load, stabilizing the refrigerant's temperature and reducing pressure drops, enhancing heat transfer efficiency and control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a two-phase refrigerant medium is used for thermal exchange, then heat transfer efficiency is improved, but pressure drops and temperature variations occur in long transport lines
Solution Approach 1:
The refrigerant flow is segmented into two separate flow paths: one for high-pressure gas and another for cooled/expanded fluid. This segmentation allows each path to be optimized independently, preventing phase variations in long transport lines while maintaining high heat transfer efficiency at the thermal load.
Solution Approach 2:
A mixing chamber acts as an intermediary between the high-pressure gas flow and the cooled/expanded flow. The mixing chamber combines these two flows to produce the final refrigerant medium that is delivered to the thermal load, ensuring stable pressure and temperature while maintaining efficient heat transfer.
2Temperature
If high pressure gas flow is mixed with cooled expanded flow before the thermal load, then temperature control is achieved, but temperature differentials increase
Solution Approach 1:
The system dynamically adjusts the flow rates of high-pressure gas and cooled/expanded fluid through controllable valves to precisely control the mixing ratio. This dynamic control allows the system to maintain minimal temperature differentials (reduced from 10°C to 3°C) while achieving accurate temperature control at the thermal load.
3Ease of operation
If standard refrigeration thermo-expansion valve is used to regulate liquid phase flow, then flow rate control is achieved, but phase variations occur in long transport lines
Solution Approach 1:
The high-pressure gas flow is prepared in advance and maintained separately from the cooled/expanded flow until the mixing chamber. This preliminary preparation ensures that phase variations are prevented in long transport lines while maintaining precise flow rate control through the thermo-expansion valve for the liquid phase.
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 maintains a higher heat transfer coefficient, especially at the heat exchanger's last portions, while preventing liquefaction and phase variations in long transport lines.
Implementation Method 1
a medium is first compressed to a high temperature gaseous state, then divided, under control, into two interdependent flows... to exchange thermal energy with a load so as to maintain the temperature at a selected target level
Implementation Method 2
the refrigerant is converted, by cooling, to liquid phase and the flow is then further cooled by expansion
Implementation Method 3
a medium is first compressed to a high temperature gaseous state
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.