Fan selection issue (a persistent problem)
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I’m facing such a situation and would appreciate some guidance from those who are familiar with this issue: For example, through actual calculations, we determine the actual operating conditions of the fan – the gas temperature is 75°C, the total pressure of the fan is 10,000 Pa, the density of the gas under these conditions is 0.9637 kg/m3, and the required flow rate is 149,000 m3/h. Using these values, we try to select the appropriate fan parameters from the catalog. However, the flow rate and total pressure values listed in the catalog are based on conditions where the temperature is 20°C, the standard pressure is 101.325 KPa, and the density of air is 1.2 kg/m3 – which are completely different from the operating conditions I need. Then, if fans are selected for the sample based on my calculated data, it’s definitely easy to make mistakes! I would appreciate some guidance – is my approach wrong, or have I gone down a wrong path?
Well, I’m thinking that it might be possible to convert the operating conditions of your medium, using the ideal gas law, into an air volume under ideal conditions. . . It should be like this. . . .
All the parameters of the fans provided by the manufacturer are based on standard conditions, so conversion is required. . . . Either convert his values under standard conditions using the equation PV=NRT, by maintaining constant molar amounts and performing proportional conversions. . . . .
This post was last edited by mfka on 2010-9-3 22:35. It’s the formula mentioned on page 3 – the gas equation from high school physics, P1×V1/T1=P2×V2/T2, which can be used for calculations. However, T1, T2 = 273.15 + room temperature
We directly use the gas equation to convert it into a flow rate under standard conditions or room temperature, and then we will select the appropriate model for you. That’s generally how it works; if you have any questions, the original poster can contact me
We directly use the gas equation to convert it into a flow rate under standard conditions or room temperature, and then we will select the appropriate model for you. That’s generally how it works; if you have any questions, the original poster can contact me
Reply to 1#: The keystrokes are very light; it can be calculated using the gas law P1×V1/T1=P2×V2/T2, by converting to standard conditions (the conditions of the sample)
You can convert it to standard conditions parameters by yourself, or you can simply provide the parameters to the equipment manufacturer, who will carry out the conversion for you.
When selecting a fan, the key factor to consider is the total pressure. The actual total pressure required is PT, while the total pressure specified in the fan’s manual under standard conditions is pt. If the density of the gas under actual conditions is x, then the formula pt = PT * 1.2 / X can be used. (1.2 is the density of air under standard conditions) The flow rate is the flow rate under actual conditions. With these two pieces of data, a suitable fan can be selected.
What Horus said upstairs is the correct answer!
A 75° wind requires a standardized conversion, and suggestions for this have already been provided above. I often use fans in my work, so I’d like to give the original poster a helpful suggestion: when checking fan specifications, for fans produced in China, try to choose those with lower values in terms of airflow volume and pressure head. I know this industry quite well; apart from the very large fans, almost none of them meet the specified **standards**.