Component in piping system are arranged in series, parallel, or in combined configurations. Each component have it’s pressure loss (or hydraulic resistance), and have it’s system characteristic curve, so the combined system curve is from the combination of individual curve.
For components in parallel, the pressure loss across each branch is equal, while the total flow rate is the sum of the branch flow rates. For components in series, the flow rate remains constant and the total pressure loss is the sum of individual losses. Understanding these basic combinations is fundamental to analyzing complex piping networks, determining pump head, and achieving proper flow balance in HVAC and fluid distribution systems.
Below picture shows the illustration of the component combine in parallel. From the picture:
Hsys = H1 = H2 = Hcommon
The total system flowrate is the sum of the individual branch flowrate:
Qsys = Q1 + Q2 + …
Parallel piping is commonly encountered in HVAC distribution system, such as chilled water piping serving multiple cooling coils. Proper balancing is critical, as differences in pipe length, diameter, or fitting can cause unequal flow distribution. Each branch have to be balanced to ensure that, at the common pressure drop, the required design flowrate is achieved.
Now, let consider the system that the component combine in series. The same flowrate passes through each component. The total pressure loss is equal to the sum of the individual pressure losses:
Hsys = H1 + H2 + …
Series piping is also commonly encoutered in HVAC distribution system; especially, in each idividual branch.
Importance in system design
Real-world piping system typically consist of combination of series and parallel components. By understanding the behavior of simple two-component combinations, you can systematically reduce complex networks into equivalent pressure losses (or resistances). This method simplifies hydralic calculation, help to efficient system design, balancing (TAB) and trobleshooting, or even optimization of the piping system.
Related notes:
Operating point of two parallel pump system – จุดทำงานของเครื่องสูบน้ำที่ต่อกันแบบขนาน
Operating point of two series pump system – จุดทำงานของเครื่องสูบน้ำที่ต่อกันแบบอนุกรม
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