Design of closed-loop cooling circulating water
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I designed a closed-loop cooling system with five pumps connected in parallel. The flow rate for each branch is expected to be 65, 65, 65, 65, and 45 L/min respectively; the diameter of the branch pipes is DN25, while that of the main pipe is DN50. The designed pressure for the circulating water is 0.3 Mpa. During actual operation, however, the flow rate of the pumps was significantly lower than the designed values, being 35/25/50/29 L/min respectively. Another branch is not in use at the moment. The operating pressure of the system was measured to be 0.55 Mpa. I wonder if anyone knows what the drawbacks of my design are, and why the flow rate cannot be increased
1. First of all, it should be understood that paralleling pumps can increase flow rate, but it’s not 1+1=2; rather, the resulting flow rate is greater than 1 but less than 2. 2. The main pipe has a DN50 diameter, while the 5 branch pipes have a DN25 diameter; the pipe diameters do not match. So the flow rate is below design, and the pressure is above design.
The diameter of the main pipe is clearly too small; it is recommended to use one with a diameter of DN75 or larger!