Multi-Stage Heat Exchanger for High-Pressure CO2 Cooling
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Solution Overview
Problem
Existing heat exchangers are unable to withstand the high pressures encountered when using CO2 (R744) as a refrigerant, leading to stress beyond their load limits, and they often require complex designs and high production costs.
Innovation Solution
A heat exchanger with separate flow channels for high-pressure and low-pressure refrigerant phases, along with a coolant, featuring an accumulator for refrigerant storage, filtering, and drying, and a compact design that includes a stacked disk or tube-fin construction to enhance pressure resistance and heat transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional heat exchanger designs are used with CO2 refrigerant, then the existing structure can be maintained, but the heat exchanger cannot withstand the high pressures and exceeds its load limits
Solution Approach 1:
The heat exchanger is divided into separate high-pressure and low-pressure flow channels, allowing each section to be optimized for its specific pressure regime. This segmentation enables the high-pressure channels to be designed with appropriate wall thickness and material properties to withstand CO2 pressures while maintaining overall system reliability
Solution Approach 2:
The patent changes the structural parameters of the heat exchanger including wall thickness, material selection, and channel geometry to accommodate high-pressure CO2 operation. These parameter adjustments ensure the heat exchanger can withstand the elevated pressures without exceeding load limits
2Strength
If complex designs are implemented to handle high pressures, then pressure resistance improves, but production costs increase
Solution Approach 1:
By segmenting the heat exchanger into standardized high-pressure and low-pressure modules, the design allows for optimized manufacturing processes for each section. This modular approach enables cost-effective production while maintaining the required pressure resistance through targeted design optimizations rather than complex overall restructuring
Solution Approach 2:
The patent optimizes structural parameters such as wall thickness and material specifications to achieve the minimum necessary pressure resistance, avoiding over-engineering. This parameter optimization balances pressure resistance requirements with manufacturing cost considerations
3Productivity
If additional cooling sections are added to increase cooling capacity, then the cooling performance improves, but the device complexity and space requirements increase
Solution Approach 1:
The patent combines the accumulator function with the heat exchanger structure, integrating refrigerant storage, separation, and heat transfer functions into a single unified component. This merging increases cooling capacity through additional heat transfer surfaces while avoiding the complexity and space requirements of separate additional cooling sections
Solution Approach 2:
The heat exchanger is designed to perform multiple functions simultaneously: heat transfer between high-pressure and low-pressure refrigerant streams, refrigerant accumulation, and phase separation. This multi-functionality increases overall system productivity without requiring additional dedicated cooling sections
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 solution increases the overall cooling capacity of the refrigerant circuit by allowing additional heat transfer between refrigerant phases and improves pressure resistance, reducing production costs and space requirements while maintaining efficient refrigerant quality.
Implementation Method 1
a first heat transfer taking place between the refrigerant in the first region of the first flow channel and the coolant in the third flow channel
Implementation Method 2
a second heat transfer taking place between the refrigerant in the second region of the first flow channel and the refrigerant in the second flow channel
Implementation Method 3
The accumulator serves as a storage medium for the refrigerant. It advantageously temporarily stores the refrigerant in the low-pressure phase. This is used to compensate for volume fluctuations in the refrigerant
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a heat exchanger (1, 30), comprising a first flow channel (23) for a refrigerant (2, 20, 39), a second flow channel (25) for a refrigerant (4, 22, 41), and a third flow channel (24) for a coolant (3, 21, 40), wherein the first flow channel (23) has a first region (23a) for initial cooling of the refrigerant (2, 20, 39) and a second region (23b) for further cooling of the refrigerant (2, 20, 39), wherein the refrigerant (2, 20, 39) can flow in a high-pressure phase in the first flow channel (23) and the refrigerant (4, 22, 41) can flow in a low-pressure phase in the second flow channel (25), wherein a first heat exchange occurs between the refrigerant in the first region (23a) of the first flow channel (23) and the coolant in the third flow channel (24) and a second heat exchange occurs between the refrigerant in the second region (23b) of the first flow channel (23) and the refrigerant in the second flow channel (25).