Modular CO2 Cascade Refrigeration for Multi-Temperature Cooling
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Solution Overview
Problem
Traditional refrigeration systems require separate closed loop systems and additional equipment when using different refrigerants for maintaining different temperatures, leading to inefficiencies and increased costs when expanding cooling capacity.
Innovation Solution
A modular cascade CO2 refrigeration system that uses a common refrigerant for both low and medium temperature loops, featuring a heat exchanger with separate sides for evaporating and condensing CO2, allowing for efficient sharing of condenser cooling and reducing the need for separate systems and equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate closed loop systems are used for different temperature applications with different refrigerants, then temperature control for multiple applications is achieved, but device complexity and equipment costs increase
Solution Approach 1:
The patent combines multiple refrigeration loops (low temperature CO2 loop and medium temperature refrigerant loop) into a single integrated system that shares common components including condenser, subcooler, expansion devices, and piping. This merging eliminates the need for completely separate closed loop systems while maintaining the ability to provide different temperature zones, thereby reducing device complexity and equipment costs.
Solution Approach 2:
The medium temperature refrigerant serves multiple functions: it acts as the primary refrigerant for medium temperature loads and simultaneously serves as the cooling medium for the CO2 condenser. This multi-functionality allows a single refrigerant system to handle both medium temperature refrigeration and low temperature CO2 refrigeration, reducing the need for separate equipment.
2Productivity
If traditional refrigeration systems expand cooling capacity by adding equipment, then cooling capacity increases, but equipment costs and system complexity increase
Solution Approach 1:
The system is divided into modular segments (medium temperature loop and low temperature CO2 loop) that can be independently configured and scaled. Each loop can be expanded by adding parallel components (compressors, condensors, expansion devices) while maintaining the integrated architecture, allowing capacity expansion without proportionally increasing overall system complexity.
Solution Approach 2:
The system incorporates adjustable expansion devices (thermostatic expansion valves, electronic expansion valves) that can dynamically control refrigerant flow to match varying cooling loads. This dynamic control allows the system to adapt to different operating conditions and scale capacity flexibly without requiring complete system redesign.
3Reliability
If separate systems are used for low temperature and medium temperature refrigeration, then temperature-specific optimization is achieved, but loss of substance and equipment costs increase
Solution Approach 1:
The patent merges the low temperature CO2 refrigeration system and medium temperature refrigeration system into an integrated cascade system that shares common refrigerant handling components, piping, and heat exchangers. This consolidation reduces the total quantity of refrigerant required compared to two completely separate systems while maintaining precise temperature control through dedicated expansion devices and heat exchangers for each temperature zone.
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 system achieves efficient temperature control for both low and medium temperature applications using CO2 as a refrigerant, allowing for scalable cooling solutions without the need for multiple systems, thereby reducing equipment costs and complexity.
Implementation Method 1
a heat exchanger configured to condense a vapor CO2 refrigerant to a liquid CO2 refrigerant
Implementation Method 2
a heat exchanger having a first side and a second side. The first side of the heat exchanger is configured to evaporate the medium temperature refrigerant
Implementation Method 3
a liquid-vapor separator configured to collect liquid CO2 refrigerant and to direct vapor CO2 refrigerant
Implementation Method 4
a low temperature expansion device configured to expand the liquid CO2 refrigerant from the liquid CO2 refrigerant supply header into liquid-vapor CO2
Data Source
AI summary
A cascade CO2 refrigeration system includes a medium temperature loop for circulating a medium refrigerant and a low temperature loop for circulating a CO2 refrigerant. The medium temperature loop includes a heat exchanger having a first side and a second side. The first side evaporates the medium temperature refrigerant. The low temperature loop includes a discharge header for circulating the CO2 refrigerant through the second side of the heat exchanger to condense the CO2 refrigerant, a liquid-vapor separator collects liquid CO2 refrigerant and directs vapor CO2 refrigerant to the second side of the heat exchanger. A liquid CO2 supply header receives liquid CO2 refrigerant from the liquid-vapor separator. Medium temperature loads receive liquid CO2 refrigerant from the liquid supply header for use as a liquid coolant at a medium temperature. An expansion device expands liquid CO2 refrigerant from the liquid supply header into a low temperature liquid-vapor mixture for use by the low temperature loads.