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Air compressor displacement calculation method

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In the equal power calculation method, I also talked about the decrease or increase of the rotational speed of the male rotor, as the exhaust pressure increases or decreases. That is, the exhaust volume decreases or increases. If the change in volumetric efficiency is considered, the displacement calculated in Example 3 can be corrected as follows: Qs1=Qs1+111%Δp1,m3/min where Δp1=p0-p1, the displacement calculated by barQs, m3/min


Equal displacement calculation method (assuming that the adiabatic efficiency and volumetric efficiency remain unchanged during this process)


The so-called equal displacement calculation method refers to the calculation method of the screw air compressor motor power increase or decrease (that is, the total torque required increases or decreases accordingly) under the condition that the displacement remains unchanged. In the sales process, it is often encountered as the exhaust pressure increases or decreases.


Equal power calculation method (assuming that the adiabatic efficiency and volumetric efficiency remain unchanged during this process)


The so-called equal power calculation means that when the power of the motor is constant (that is, the total torque required is constant), the speed of the male rotor decreases or increases, and the exhaust pressure increases or decreases. That is, the exhaust volume decreases or increases (The speed of the male rotor is proportional to the displacement) This calculation method is often encountered in the process of engineering technology development. For those who only reduce the exhaust pressure, and the speed of the male rotor does not increase correspondingly, although the displacement will be more The original model is a little larger, it is only due to the increase in volumetric efficiency due to the decrease in exhaust pressure; if the exhaust pressure is much reduced than the original model, and the speed of the male rotor does not increase correspondingly, it will produce The phenomenon of "big horse-drawn carts" that I often talk about brings some unnecessary power loss to users invisibly.


Give an example of how to use a quick calculation table for calculations


Example 1. The customer needs to order 3 sets of 32m3/min110MPa air compressors. 34m3/min017MPa is calculated based on the equal displacement calculation method, and my existing product LS25S-250L. Because the user needs a higher exhaust pressure than the existing air compressor Rated exhaust pressure, so p1 is 017MPap2 is 110MPa. According to the speed calculation table, P1/P2=0182398, when P1=250HP3, then P2=303HP, that is to say, use LS25S-250L host speed ratio, and use 300HP motor theoretically Reluctantly meet the needs of users. If I further understand and find that the user's maximum working pressure can be accepted as long as it is not less than 0195MPa, then theoretically a 300HP motor can meet the user's needs.


Example 2. The customer needs to order 3 sets of 1415m3/min016MPa air compressor 1412m3/min110MPa and my existing product LS20-125HH.


The calculation is carried out according to the equal displacement calculation method. So p1 is 016MPap2 is 110MPa. According to the speed calculation table, P1/P2=0175481, because the exhaust pressure required by the user is less than the rated exhaust pressure of the existing air compressor. When P2=125HP , Then P1 is 9414HP


In other words, using LS20-125HH main engine speed ratio. And my existing product LS25S-300H, with 100HP motor theoretically can fully meet the needs of users. Example 3. According to market demand, I develop LS25S-300HH model. 3812m3/min018MPa


The calculation is based on the equal power calculation method. Therefore, p1 is 018MPa, because the required discharge pressure is greater than the rated discharge pressure of the existing air compressor. P2 is 110MPa, and Q2/Q1=0188723 is found according to the speed calculation table, when Q1 is 3812m3/min When, Q2 is 34m3/min. Through the calculation of the displacement, I can further calculate the speed ratio of the required host (this calculation process is omitted)


Through the above 3 examples, I can quickly calculate the required parameters.


Only reduce the exhaust pressure. Its exhaust calculation method does not change other parameters.


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