Centrifugal pump efficiency
Thread Content
Why is the efficiency of centrifugal pumps so low, even less than 50%?
Since the power of the pump N(KW) = head (m) × flow rate (m3/s) × 1000 (specific weight of water, Kg/m3) ÷ 102 (power conversion factor) ÷ η (efficiency of the pump), the efficiency of the pump can be calculated from this formula. By measuring the current and voltage (which allows the pump’s power to be calculated), and by measuring the flow rate and head, the pump’s efficiency can be determined. The same centrifugal pump can have different operating points; the user manuals provided by manufacturers usually indicate the operating conditions under which the highest efficiency is achieved. At this point, the efficiency is around 70-80%, which is not considered low. So maybe the pump chosen there isn’t suitable, or the motor associated with it isn’t compatible, which leads to inefficiency; you can consult the manufacturer about this.
Different pumps have different efficiencies; how can they all be 40-50%?
It seems to be a problem with his improper use
It shouldn’t be this low; it’s possible that there is a significant deviation from the designed operating conditions, or else the manufacturer’s design is poor. Generally, it should be around 70
If the pump is too large, its efficiency will be lower； If the pump is smaller, its efficiency will be higher ； Generally, the pump’s performance curve is used to guide its actual operation
Perhaps he was referring to one of their pumps, whose impeller design is different – it’s an open impeller
Sometimes, due to operational requirements, it is indeed difficult to choose a pump with high efficiency. When the pump efficiency is too low, it is possible to consider switching to a different type of pump; ordinary centrifugal pumps won’t work, so pipe pumps or similar alternatives can be used
Yeah, it’s clearly on the low side; ours at the company are between 70 and 80
It’s also possible that the pump is running in reverse. We’ve encountered this issue of low pump output once before; we took the pump apart and checked it thoroughly, but nothing was found wrong, until we realized there was a problem with the electrical wiring.
Someone has replied to this question again today. I would like to ask: how did you determine that his efficiency is low? The first thing to do is probably to verify whether your calculations are correct, and only then can we discuss the issue of efficiency. The issue of efficiency can be easily analyzed once you figure out how many types of losses exist in this process, and what factors are related to each of those losses.