Cascaded Refrigeration for Wide-Range Process Tool Temperature Control
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Solution Overview
Problem
Conventional refrigeration systems struggle to provide a wide temperature range from −80° C. to +60° C. with high efficiency and reliability, especially in high-capital industries like semiconductors, due to space and cost constraints, and inefficiencies arise when heating is required to counteract over-cooling.
Innovation Solution
An intercoupled cascaded arrangement of modular refrigeration units, with one unit using a refrigerant of higher evaporation point for mid-range operation and another with a lower evaporation point for lower temperatures, along with a heater in the thermal transfer fluid loop, allowing for efficient temperature control and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional refrigeration systems are used to achieve wide temperature range from -80°C to +60°C, then temperature coverage is improved, but system complexity and space requirements increase significantly
Solution Approach 1:
The refrigeration system is divided into multiple independent modules, each capable of operating within a specific temperature range. These modular units can be independently controlled and combined to achieve the overall wide temperature range requirement, reducing the complexity of any single module while maintaining system versatility.
Solution Approach 2:
The refrigeration modules are designed with multi-functionality to handle both cooling and heating operations. By integrating heating capability into the refrigeration modules, the system can operate across the full temperature range from -80°C to +60°C without requiring separate heating systems, thereby reducing overall system complexity.
2Adaptability or versatility
If multiple refrigeration units are cascaded to provide wide temperature range, then temperature coverage is improved, but space requirements and cost increase
Solution Approach 1:
The modular refrigeration units are designed to be nested or compactly arranged within each other or in a space-efficient configuration. This nesting approach allows multiple temperature control stages to be integrated into a compact footprint, reducing the overall space requirements while maintaining the wide temperature range capability.
Solution Approach 2:
Multiple refrigeration functions are merged into integrated modular units that share common components such as compressors, heat exchangers, and control systems. This consolidation reduces redundant components and minimizes the total space required compared to separate standalone refrigeration units.
3Adaptability or versatility
If refrigeration units operate intermittently to provide heating, then heating capability is improved, but reliability decreases
Solution Approach 1:
The refrigeration modules are designed to operate continuously rather than intermittently, with integrated heating elements that can provide heating capability while the refrigeration cycle runs. This continuous operation mode maintains system reliability by avoiding frequent start-stop cycles while still delivering both cooling and heating functions.
Solution Approach 2:
The refrigeration modules incorporate multi-functionality to simultaneously or alternatively provide both cooling and heating operations through integrated heating elements. This eliminates the need for separate heating systems and allows continuous operation to serve dual purposes, improving reliability while maintaining versatility.
4Adaptability or versatility
If heating is employed to counteract over-cooling, then temperature flexibility is improved, but energy efficiency decreases
Solution Approach 1:
The system converts the waste heat generated during refrigeration operation into a useful heating resource. By capturing and redirecting this waste heat to provide heating when needed, the system eliminates energy waste and improves overall energy efficiency while maintaining temperature flexibility across the full operating range.
Solution Approach 2:
The system recovers waste thermal energy from the refrigeration cycle that would otherwise be discarded. This recovered heat is utilized to provide heating capability, transforming an energy loss into a beneficial resource and significantly improving the overall energy efficiency of the system while maintaining versatile temperature control.
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 provides a smooth continuum of operating temperature levels, efficient operation, and high reliability, enabling continuous temperature control across the desired range while minimizing space and cost, and preventing catastrophic failures through excess gas chambers and pressure regulation systems.
Implementation Method 1
a refrigerant having a relatively higher evaporation point to provide a refrigeration capacity predominantly for midrange operation
Implementation Method 2
the gaseous pressurized output of the compressor is condensed
Implementation Method 3
heat exchangers/evaporators to provide the thermal capacity needed for cooling or heating thermal transfer fluid
Implementation Method 4
thermal transfer fluid that circulates through the process tool
Implementation Method 5
expansion valve devices
Implementation Method 6
a thermal expansion system that is precisely controllable
Data Source
AI summary
A system and method for maintaining the temperature of a thermal transfer fluid at a selectable level within a wide temperature range, so as to operate a process tool in a chosen mode employing at lease two cascaded stages, each operating with a different fluid in a separate refrigeration cycle. By interrelating energy transfers between parts of upper and lower stages, thermal efficiency is maximized and a smooth continuum of temperature levels can be provided. The refrigerants advantageously have vaporization points below and above ambient, for upper and lower stages respectively, and employs the upper stage for a constant refrigeration capacity, controlling the final temperature with the lower stage. The system allows for a further extension of range because the thermal transfer fluid can be heated for some process tool modes as the refrigeration cycles are run at low loads.