Discussion on pump efficiency
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There is currently a 5-stage variable-frequency horizontal oil pump that operates in two modes, 1 and 2; these modes correspond to two different types of fluids. The flow rate is the same in both modes, but the head pressure differs, with mode 1 having a higher head pressure than mode 2. It is possible to switch to mode 2 by using variable frequency to reduce the speed. How should the efficiency be calculated in this case? Are there any standards or books that provide the formula for such calculations?
In situations like this, we assume that efficiency remains more or less the same; of course, there are certainly some variations, but they should not be significant； Let’s see what other sea friends have to say: lol
This post was last edited by 3983596_FPPZ on 2019-1-24 at 13:24. If it is a purely theoretical calculation, many known conditions are required, and the calculation process is overly complicated. You can find the theoretical basis for this in Chapter 3, Section 5 of Teacher Guan Xingfan’s \"Modern Pump Design Manual\": Similar Parabolas and Their Applications (page P45). However, in practical use, if the head and speed differ by very little, the efficiency can be considered essentially constant.
The effective power is calculated based on flow rate, head, and medium density; the output power of the motor is then determined using the motor’s current and efficiency. The transmission efficiency of the coupling can be ignored, so the efficiency can be calculated by reverse inference
How much does the viscosity of the two media differ?
The calculations are too theoretical and complex; the best approach is to measure the current, voltage, head, flow rate, and efficiency under actual operating conditions
There are actually three operating conditions; for the first two, the flow rate is 2000 m3/h and the viscosity is less than 40 cP, so viscosity can be ignored. For the third flow rate of 1200 m3/h, the viscosity is over 200 cP, which affects the head pressure. It’s difficult to determine the efficiency and power requirements when considering all three operating conditions at the same time.
It is still in the design phase; there is no actual product yet
To submit documents to clients, it is necessary to show the differences