Parallel and Series Pump Operation
We have seen examples of the mini-chillers operating in parallel, e.g. where they are connected
together via a common supply and return header pipe. Such installations are common when the
single chiller do not have sufficient cooling capacity. In the parallel operation, the water pumps
will work together to deliver a higher water flowrate (which is equivalent to the summation
of each
individual pump flowrate) at the operating head pressure.
Example
: Two mini-chillers of the same model are connected together to a load as shown
schematically (simplified) below:
header
C1
Load
C2
The pump in each chiller is delivering a flow of ϖ GPM. Assume that the friction loss
in each branch of the header pipe is the same. Therefore, the flow in the load will
be 2ϖ GPM .
If the total pipe friction loss is P ft, we can have the following pump curves:
Head single pump curve
pressure
combined pump curve
P
ϖ
2
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