PuK - Process Technology & Components 2024
A technical trade magazine with a history of more than 60 years.
A technical trade magazine with a history of more than 60 years.
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Pumps and Systems<br />
High-efficiency pumps<br />
High-efficiency pumps<br />
The best control<br />
Jochen Krings<br />
High energy costs are once again<br />
calling attention to the savings potential<br />
of circulating pumps. But<br />
how big are the differences between<br />
the latest models and older<br />
ones? And when is it worth it to replace<br />
them?<br />
The key to the enormous efficiency<br />
gains from modern high-efficiency<br />
pumps is their motor design and control.<br />
The Grundfos Alpha2 series, for<br />
example, is equipped with a highly<br />
efficient permanent magnet motor.<br />
Unlike conventional asynchronous<br />
motors, this one does not require<br />
ener gy to magnetise the rotor, making<br />
it around 30 per cent more efficient.<br />
As well as this, the pump’s<br />
components have been optimised to<br />
reduce typical losses to a minimum.<br />
These include the stator windings,<br />
eddy currents in the stator and rotor<br />
fins, the flow of current in the rotor<br />
rods and end rings, and friction in the<br />
bearings. The hydraulic has been optimised<br />
down to the last detail using<br />
computational flow simulations. The<br />
impeller, for example, has been completely<br />
redesigned from previous<br />
generations to convert the rotation of<br />
the motor shaft into flow even more<br />
efficiently.<br />
The materials also help to improve<br />
efficiency. The permanent magnet rotor<br />
is made from neodymium, and the<br />
motor can is made from composite<br />
material. The housing has a cataphoretic<br />
coating (applied using an electrochemical<br />
dip coating process) that not<br />
only provides a high degree of protection<br />
from corrosion, but also reduces<br />
flow resistance thanks to its especially<br />
even surface. Here too, the developers<br />
have fine-tuned every detail to<br />
achieve maximum efficiency.<br />
Smart control<br />
The introduction of electronic speed<br />
control in the 1990s was an important<br />
step in making pumps more efficient.<br />
There has, however, been further<br />
significant progress in this area<br />
too. Conventional control only returns<br />
an output variable such as the<br />
differential pressure back to the control<br />
variable. The special system conditions,<br />
such as the loss coefficients<br />
of pipes, fixtures, boilers and radiators,<br />
are largely ignored. As a result,<br />
the pump does not run on the system’s<br />
optimum control curve.<br />
Modern self-adapting pumps<br />
such as the Grundfos Alpha2, on the<br />
other hand, regularly analyse the system<br />
conditions and optimise the position<br />
of the proportional pressure<br />
Fig. 2: The latest high-efficiency pumps, such as the Alpha2, are significantly more efficient<br />
even than their predecessors, which were already among the most efficient of their time<br />
Fig. 1: Permanent motor, hydronic optimisation down to the last detail and smart control<br />
enable the highest level of efficiency (Grundfos Alpha2) (All images: Grundfos)<br />
curve automatically. The advantage<br />
of this is that the pump always runs<br />
on the optimum curve, so it does not<br />
consume more energy than necessary.<br />
It is not affected by short-term<br />
fluctuations in demand as these are<br />
compensated for by the proportional<br />
pressure control. The AutoAdapt<br />
technology also simplifies the commissioning<br />
process. All the installer<br />
needs to do is connect the power<br />
supply, and the pump will take care<br />
of optimising its settings itself.<br />
18 PROCESS TECHNOLOGY & COMPONENTS <strong>2024</strong>
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