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How to select the appropriate number of tubes for air heat exchangers

The number of air heat exchanger passes selected depends mainly on the allowable pipe pressure drop and the temperature range variation of the fluid. The tubing process allows for a wide range of pressure drops and fluid temperature variations, and multiple pipe passes are available. When the single-phase fluid is cooled, the flow rate is increased as much as possible under the condition of meeting the allowable pressure drop, the general liquid flow rate is between 0.5-1.5m/s, and the gas flow rate is about 5-10kg/(㎡.s). It is advantageous for the fluid in the tube to be in a turbulent state, so it is more appropriate to choose more than two pipe strokes. For condensation processes, if the logarithmic mean temperature difference correction factor is less than 0.8, a two-tube or multi-tube pass should be considered.

Classification of surface heat treatment

Surface heat treatment technology can be roughly divided into three categories: overall surface heat treatment, surface heat treatment and chemical surface heat treatment. The same metal chooses different surface heat treatment technology, which can achieve different arrangements, and then has different functions. Let's analyze the specific problem specifically to see what three methods of surface heat treatment are

2021

09-15

Principle of vacuum nitriding treatment

Gas nitriding generally uses anhydrous ammonia (or ammonia + hydrogen, or ammonia + nitrogen) as the nitrogen supply medium. The entire nitriding process can be divided into three stages

2021

09-15

Classification and hardness testing methods for heat treatment plants

The hardness of the heat treated workpiece is tested by a hardness tester. PHR series portable surface Rockwell hardness tester is very suitable for detecting the hardness of surface heat treatment workpieces, and can test various surface heat treatment workpieces with an effective depth of more than 0.1mm. Simple operation, easy to use, low price, can directly read the hardness value

2021

09-15

Common sense of vacuum heat treatment

When disposing of titanium alloy in vacuum furnace, it is not suitable to use nitrogen as a cooling gas, because titanium and nitrogen react at high temperature, forming golden yellow titanium nitride.

2021

09-15