Ductile Stainless Steel Refrigerant Pipes for Bendable Air Conditioners
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Solution Overview
Problem
Conventional air conditioner refrigerant pipes, particularly those made of copper, face issues with scale accumulation, insufficient pressure resistance, vulnerability to vibration, high installation complexity, and cost due to copper's properties, while stainless steel pipes offer better corrosion resistance and strength but are difficult to bend and install due to excessive hardness.
Innovation Solution
A ductile stainless steel pipe with a delta ferrite matrix structure of 1% or less and an austenite matrix structure, having an average grain diameter of 30 μm to 60 μm, is used for the refrigerant pipes, providing the necessary strength, hardness, and ductility to match copper pipes while allowing for easier installation and reduced thickness without compromising pressure resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel pipe is used to replace copper pipe, then corrosion resistance and pressure resistance are improved, but ductility and ease of bending are deteriorated
Solution Approach 1:
The patent applies parameter changes by precisely controlling the microstructural parameters of stainless steel - specifically maintaining delta ferrite content at 1% or less and controlling average grain diameter to 30-60 μm. This microstructural parameter control transforms the material properties to achieve both high strength and improved ductility, resolving the contradiction between corrosion resistance and ease of bending.
Solution Approach 2:
The patent utilizes composite material principles by creating a specific microstructural composition within the stainless steel - a matrix structure combining austenite and controlled delta ferrite phases. This internal composite structure provides both the corrosion resistance of stainless steel and the ductility needed for bending operations.
2Stress or pressure
If stainless steel pipe is used to replace copper pipe, then pressure resistance is improved, but hardness and ease of installation are deteriorated
Solution Approach 1:
The patent changes the microstructural parameters of the stainless steel - controlling delta ferrite to 1% or less and grain diameter to 30-60 μm - which simultaneously achieves high pressure resistance while maintaining sufficient ductility for installation operations such as bending and cutting.
3Ease of manufacture
If copper pipe is used, then ease of bending and installation is improved, but pressure resistance and corrosion resistance are deteriorated
Solution Approach 1:
The patent creates a composite microstructure within the stainless steel comprising austenite matrix with controlled delta ferrite phases. This internal composite structure provides both the mechanical strength for pressure resistance and the ductility for ease of bending, replacing copper's advantages while eliminating its deficiencies.
4Quantity of substance
If copper pipe is used, then cost is reduced, but scale accumulation and reliability are deteriorated
Solution Approach 1:
The patent replaces the inexpensive but unreliable copper pipe with stainless steel pipe that, while potentially more expensive initially, provides superior long-term reliability by preventing scale accumulation. The controlled microstructure ensures durability and resistance to degradation, making the system more reliable over its service life.
Data Source
AI summary
The present invention relates to an air conditioner. A first invention according to the present embodiment is an air conditioner which has a refrigeration capacity of 16 kW to 28 kW, inclusive, and uses a mixed refrigerant R134a as a refrigerant, and in which a refrigerant pipe includes a ductile stainless steel pipe having 1% or less of a delta-ferrite matrix structure with respect to the grain size area thereof.