Copper Pipe Oxide Film Formation for Corrosion-Resistant Water Heaters
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Solution Overview
Problem
Copper water pipes used in heat pump water heaters are prone to corrosion when exposed to water with high corrosion tendencies, leading to potential leaks, and inhibitors cannot be effectively used in user-supplied water due to the once-through nature of the system.
Innovation Solution
A method involving the formation of a copper oxide film on the inner surface of copper pipes by injecting a chloride ion-containing aqueous solution, such as sodium chloride, which can be circulated to ensure uniformity and stability, and optionally preceded by an acid pretreatment to remove surface deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water flows continuously through copper pipes in heat pump water heaters, then the water supply function is maintained, but corrosion occurs and holes are formed in the pipes
Solution Approach 1:
The patent applies preliminary action by forming a protective copper oxide film on the inner surface of copper pipes before corrosion can occur. This is achieved by injecting a chloride ion-containing aqueous solution into the pipe, which reacts with the copper surface to create a stable oxide layer that prevents subsequent corrosion from corrosive water
Solution Approach 2:
The patent converts the harmful effect of chloride ions (which typically accelerate copper corrosion) into a beneficial protective mechanism. By controlling the injection of chloride ion-containing solution, the patent induces the formation of a stable copper oxide film that actually protects the pipe from further corrosion by corrosive water
2Manufacturing precision
If an acid aqueous solution is injected to remove surface deposits, then the inner surface homogeneity is improved, but additional processing steps are required
Solution Approach 1:
The acid aqueous solution injection serves as a preliminary action to prepare the inner surface by removing deposits and oxides before the main copper oxide film formation step. This ensures a clean, homogeneous surface that promotes uniform film formation in the subsequent chloride ion treatment
Solution Approach 2:
The patent utilizes parameter changes by controlling the concentration and composition of aqueous solutions (acid solution followed by chloride ion solution) to achieve surface preparation and film formation. The chemical parameters of the solutions are optimized to remove deposits effectively while promoting uniform oxide film formation
3Manufacturing precision
If chloride ion-containing solution is circulated continuously, then film uniformity and stability are improved, but flow-induced shearing forces may interfere with film formation
Solution Approach 1:
The patent applies periodic action by alternating between circulation modes: initially circulating the chloride ion-containing solution to ensure uniform distribution and film formation across the inner surface, then stopping circulation to allow the film to set without flow-induced shearing forces, and repeating this cycle to achieve both uniformity and film stability
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 copper oxide film acts as a reliable anti-corrosion protective layer, reducing the risk of corrosion and extending the lifespan of the pipes even when exposed to corrosive water conditions.
Implementation Method 1
forming a copper oxide film (12) on the inner surface of a copper pipe (11) through injecting a chloride ion-containing aqueous solution (L2) into the copper pipe (11)
Implementation Method 2
removing a surface deposit (30) from the inner surface of a copper pipe (11) through injecting an acid aqueous solution into the copper pipe (11)
Data Source
AI summary
A pipe is manufactured through injecting a chloride ion-containing aqueous solution into a copper pipe to fill the copper pipe, thereby forming a copper oxide film on an inner surface of the copper pipe.