High-Strength Copper Alloy Tubes for CO2 Refrigeration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper tubes used in heat exchangers for CO2 refrigeration face challenges with high pressure requirements, necessitating thick walls that increase weight, cost, and processing difficulties, while steel alternatives have inefficiencies and higher costs.
Innovation Solution
Development of high-strength Cu alloys with small wall thicknesses for heat exchanger tubes, allowing for efficient processing and reduced material usage, featuring a yield point over 160 N/mm² and tensile strength over 300 N/mm², enabling seamless or welded tube designs with smooth or structured surfaces for enhanced heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If copper tubes made of Cu-DHP are used in CO2 refrigeration systems, then good processability and low cost are achieved, but the tube wall thickness must be very large to withstand high pressures
Solution Approach 1:
The patent changes the material parameters by developing a Cu-Zn-P-Ni-Fe-Sn-Co alloy with specific compositional ranges (Zn: 2-10%, P: 0.01-0.1%, Ni: 0.1-1%, Fe: 0.1-0.5%, Sn: 0.1-0.5%, Co: 0.01-0.1%) to achieve superior mechanical properties. This allows the tube wall thickness to be reduced from conventional dimensions to just 0.5-2.0 mm while maintaining the required pressure resistance for CO2 systems operating at up to 130 bar.
Solution Approach 2:
The patent creates a composite alloy system combining multiple elements (Cu-Zn-P-Ni-Fe-Sn-Co) to achieve a synergistic effect. The base copper provides ductility and formability, while zinc contributes to strength, and the added elements (P, Ni, Fe, Sn, Co) work together to enhance tensile strength and yield point. This composite material approach enables thin-walled tubes to withstand high CO2 pressures without sacrificing processability.
2Strength
If tube wall thickness is increased to withstand high CO2 pressures, then pressure resistance is improved, but workability including expansion and bending deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters to achieve a balance between strength and ductility. The controlled ranges of alloying elements create a material with high tensile strength (>300 MPa) and yield point (>160 MPa) while maintaining elongation properties that enable bending and expansion. This parameter optimization allows thin-walled tubes (0.5-2.0 mm thickness) to be formed into complex heat exchanger geometries without cracking or failure.
3Strength
If steel or stainless steel pipes are used to meet pressure requirements, then pressure resistance is improved, but processability and costs worsen
Solution Approach 1:
The patent modifies the material composition by using a copper-based alloy system rather than steel, while achieving comparable or superior pressure resistance through the Cu-Zn-P-Ni-Fe-Sn-Co composition. This allows the material to maintain the excellent formability, solderability, and thermal conductivity characteristics of copper while withstanding CO2 pressures up to 130 bar, eliminating the need to switch to harder-to-process steel materials.
4Strength
If tube wall thickness is increased to withstand high pressures, then pressure resistance is improved, but material costs and equipment costs increase
Solution Approach 1:
The patent changes the material parameters by using a high-performance copper alloy with optimized composition to achieve greater strength per unit thickness. This enables the use of thin-walled tubes (0.5-2.0 mm) that require significantly less material volume compared to conventional thick-walled copper or steel tubes, thereby reducing both material costs and manufacturing costs while maintaining the required pressure resistance for CO2 refrigeration systems.
Data Source
AI summary
The invention relates to the use of a heat exchanger tube, comprising a copper alloy, which contains the alloying elements [in percent by weight] 0.05 - 3% Fe, 0.01 - 0.15% P, and optionally 0.05 - 0.2% Zn, 0.02 - 0.05% Sn and residual Cu as well as unavoidable impurities, as a gas-cooler, condenser or evaporator tube of a refrigerator or heat pump operating with CO2.