Maximum temperature of aluminum plate-fin heat exchangers
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How is the design temperature of 65 degrees for aluminum plate-fin heat exchangers determined? What are the consequences when it exceeds 65 degrees?
Because materials such as 5083, which have a magnesium content of over 3%, are generally not used at temperatures above 65 degrees Celsius. . . It’s too much; it’s prone to corrosion.
As recommended by JB/T4747, it should be used at temperatures below 47°.
Besides the corrosion issue, are there any considerations regarding brazing strength?
At this temperature, the solder will not melt. .
Will there be any issues with the strength? Or, could the heat exchanger be damaged due to excessive stress?
Above 65 degrees, the allowable stress of many aluminum alloys decreases, which affects the strength of the equipment. When the magnesium content in aluminum-magnesium alloys is high, intermetallic compounds such as Mg2Al3 and Mg5Al8 precipitate at the grain boundaries, which renders these alloys susceptible to stress corrosion in certain media. Stress corrosion does not occur unless the alloy is used at temperatures below 65°C; therefore, for aluminum-magnesium alloys with a magnesium content exceeding 3%, the designated operating temperature is limited to 65°C or less. The design temperature for plate-fin heat exchangers ranges from -269 to 200. When the design temperature exceeds 65 degrees, we cannot use alloys with a high magnesium content; when other aluminum alloys are used, design must be carried out using the allowable stress at their maximum design temperature.