Plate Heat Exchanger Brazing via Port-Directed Gas Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing brazing methods for plate heat exchangers are time-consuming and energy-intensive due to slow heat conduction through the stack of plates, which can lead to excessive grain growth and loss of mechanical strength, and undesirable structures like Chromium carbides.
Innovation Solution
A method and system that involves conducting a gas through nozzles into port openings of a stack of heat exchanger plates, using a support with aligned holes to direct the gas flow through interplate flow channels for rapid and uniform heating or cooling, thereby improving material properties by reducing time at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heat is transferred to the stack of plates by radiation and convection from the furnace, then the heating process is simple to implement, but the heat transport inside the stack is slow and time-consuming due to heat conduction through individual plates
Solution Approach 1:
The patent uses gas flow (pneumatics) to directly heat the plates from both sides simultaneously. Gas nozzles deliver heated gas through the flow channels, enabling rapid heat transfer that bypasses the slow conduction process through plate thickness, thus reducing brazing cycle time while maintaining manufacturing simplicity
Solution Approach 2:
The invention transitions from one-dimensional heat transfer (external convection/radiation to plate surfaces) to three-dimensional heat transfer by injecting heated gas directly into the internal flow channels. This allows heat to reach the entire plate volume simultaneously from multiple directions, dramatically reducing heating time
2Reliability
If prolonged heating time is used to ensure complete brazing, then the brazing process is more thorough, but excessive grain growth and loss of mechanical strength occur
Solution Approach 1:
Gas nozzles deliver heated gas directly through the flow channels, enabling rapid and uniform heating that achieves complete brazing in shorter time. The direct gas contact ensures thorough heating of all plate surfaces and joints, eliminating the need for prolonged heating that would cause grain growth
Solution Approach 2:
The invention changes the heating parameters by using direct gas flow through internal channels rather than external convection. This enables higher effective heating rates and more uniform temperature distribution, achieving complete brazing at optimized temperatures and times that prevent excessive grain growth
3Device complexity
If conventional heating from furnace walls is used, then the furnace design is simple, but considerable amounts of energy are required for heating
Solution Approach 1:
The system uses gas nozzles to deliver heated gas directly into the flow channels, creating efficient convective heat transfer. This direct internal heating method significantly reduces energy consumption compared to conventional furnace heating, as heat is delivered precisely where needed without losing energy to furnace walls and surrounding environment
Solution Approach 2:
The heat exchanger structure itself serves as the heating medium delivery system. The existing flow channels are utilized to transport heated gas directly to all plate surfaces, eliminating the need for separate heating elements and reducing overall system complexity while improving energy efficiency
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 results in shorter brazing cycles, improved mechanical and corrosion properties of the heat exchanger, and enhanced product quality by preventing excessive grain growth and undesirable structures.
Implementation Method 1
conducting gas from at least one of said nozzles into at least one of the port openings of the stack of heat exchanger plates and thereby create a flow of gas through the interplate flow channels
Implementation Method 2
Heat is transferred from or to the furnace to or from the peripheral surfaces of the stack of plates by means of radiation and or convection. However, the heat transport inside the stack of plates is controlled by heat condition. Heat conduction through the individual plates is a slow and time consuming process.
Implementation Method 3
the rapid cooling can result in quenching. It has been found that the mechanical and corrosion properties of the base material (the material of the heat exchanger plates) are improved when time at elevated temperatures is reduced and the cooling speed is increased.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method for brazing a plate heat exchanger (10) having a stack of heat exchanger plates with depressions and elevations forming interplate flow channels and port openings being in selective fluid communication with said interplate flow channels, the method comprising the steps of placing the stack of heat exchanger plates in a heating chamber (16) of a furnace (15), conducting a gas for changing the temperature of the stack of heat exchanger plates through a plurality of nozzles (23) inside the heating chamber (16), and conducting gas from at least one of said nozzles (23) into at least one of the port openings (O1-O4) of the stack of heat exchanger plates. Disclosed is also a system for brazing a plate heat exchanger (10).