Silver Coating of Plate Heat Exchangers by Alternating Flow
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Solution Overview
Problem
Existing methods for reducing germs like Legionella in residential hot water systems, such as plate heat exchangers, face challenges including germ stagnation, chemical treatment complications, and increased pressure due to silver-plated solutions, while high-energy methods for silver nitrate evaporation are inefficient.
Innovation Solution
A method involving an aqueous silver nitrate solution circulated through copper-soldered plate heat exchangers in alternating directions to diffuse silver ions into the copper, ensuring effective coating without significant pipe reduction, using a controlled flow and temperature to enhance antimicrobial properties and prevent germ accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver nitrate solution is circulated through plate heat exchanger to deposit silver coating, then antimicrobial properties are improved, but energy consumption increases due to high temperature evaporation required
Solution Approach 1:
The patent changes the parameters of the silver nitrate solution by adjusting its concentration (1-10% by weight) and temperature (20-80°C) to achieve effective silver deposition without requiring high-temperature evaporation. The solution is circulated through the heat exchanger for a controlled period (1-24 hours) to allow sufficient diffusion of silver ions into the copper, thereby reducing energy consumption while maintaining antimicrobial effectiveness.
2Reliability
If fabric or mesh is placed in drinking water pipes to reduce germs, then antimicrobial properties are improved, but pipe cross section is reduced significantly
Solution Approach 1:
The patent replaces the mechanical system of fabric or mesh placement with a chemical diffusion system. An aqueous silver nitrate solution is circulated through the plate heat exchanger, allowing silver ions to diffuse into the copper material. This creates an antimicrobial surface coating without any physical obstruction, thereby maintaining full pipe cross-section and water flow capacity while achieving germ reduction through the antimicrobial properties of silver.
3Ease of manufacture
If silver nitrate solution is circulated in single direction through plate heat exchanger, then coating process is simplified, but coating uniformity deteriorates at flow inlet and return
Solution Approach 1:
The patent implements periodic action by circulating the silver nitrate solution through the plate heat exchanger in alternating directions. The solution flows through the exchanger in one direction for a certain period, then the flow direction is reversed. This periodic reversal ensures that all surfaces, including flow inlet and return areas, receive uniform exposure to the silver nitrate solution, achieving consistent silver deposition throughout the entire heat exchanger surface.
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
This approach provides a reliable, cost-effective, and energy-efficient silver coating for plate heat exchangers, maintaining water flow and reducing germ growth, while enhancing the durability and resistance of copper-soldered heat exchangers to aggressive drinking water.
Implementation Method 1
the material forming the coating is an aqueous silver nitrate solution and this is conducted in at least one plate heat exchanger and circulated through it in order to diffuse into the copper
Data Source
AI summary
The object of the invention is therefore to create a method for coating a plate heat exchanger with silver, which is simple, inexpensive and reliable to implement and also allows a reduction in germs on the inner surface of the plate heat exchanger. Process for the internal coating of a plate heat exchanger brazed by copper, wherein the material forming the coating is an aqueous silver nitrate solution and this is passed into at least one plate heat exchanger and circulated through it to diffuse into the copper and then passed out of the heat exchanger again, wherein the silver nitrate solution flows through the at least one plate heat exchanger in alternating flow directions.