System head curve for tree piping system

In summary, to plot the system curve for a branched piping system, you will need to calculate the head at each branch by using equations such as the Colebrook-White equation and the Bernoulli equation. You will also need to account for kinetic energy losses and use the Hardy Cross method to solve for the flowrates in each branch. Once you have calculated the head at each branch, you can plot the total head against the total flowrate to get the system curve.
  • #1
firavia
137
0
as we know to draw the system curve of a piping system we have to change the value of
Q total and get a head for each value we put in the following equation : H=Hstatic +Kq^2
where K is the sum of major and minor losses.

what if we have a piping system that have many branches "tree -system" , how can we plot the system curve then ?
if we take the longest run and apply the above equation the change in Q all along the pipe will interrupt our calculation because the foumula will look like the following:
H=hst +K1Q1+K2Q2+K3Q3 ...

BUT usuallly for a single pipe system we have 1 Q all along the pipe which is the total Q , what do we do in the case of branched system ?
 
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  • #2
In order to plot the system curve for a branched piping system, you will need to calculate the head at each branch and then add them together to get the total head. This can be done by calculating the total headloss through each branch, which is usually done using the Colebrook-White equation or the Moody diagram. You will also need to account for the kinetic energy losses in each branch, which can be done using the Bernoulli equation. Once you have calculated the head at each branch, you can then plot the total head against the total flowrate to get the system curve. Additionally, you can use the Hardy Cross method to solve for the flowrates in the branches of the system. This method requires that you set up a system of equations with the total flowrate as the unknown variable. The equations use headlosses through each branch to calculate the flowrates in each branch. Once you have solved for the flowrates in each branch, you can then plot the total head against the total flowrate to get the system curve.
 

1. What is a system head curve for a tree piping system?

A system head curve for a tree piping system is a graphical representation of the relationship between the flow rate and the total dynamic head (TDH) in a piping system. It shows the head loss due to friction and elevation changes in the system, and is used to determine the required pump head and flow rate for optimal system performance.

2. How is a system head curve calculated?

A system head curve is calculated by using the Bernoulli's equation, which takes into account the fluid velocity, density, and elevation changes in the system. Other factors such as pipe size, length, and roughness are also considered when calculating the head loss. This process is typically done using specialized software or through manual calculations by a trained engineer.

3. Why is a system head curve important for a tree piping system?

A system head curve is important because it helps in selecting the right pump for the system. By understanding the relationship between flow rate and TDH, engineers can determine the most efficient pump size and flow rate that will meet the system's requirements. This can help in reducing energy costs and ensuring optimal performance of the piping system.

4. How does a system head curve affect the pump selection?

The system head curve directly affects the pump selection as it provides the necessary information for determining the required pump head and flow rate. The pump selected should have a head-capacity curve that intersects with the system head curve at the desired flow rate. If the curves do not intersect, the pump will either not deliver the required flow rate or will operate at an inefficient point.

5. Can a system head curve change over time?

Yes, a system head curve can change over time due to various factors such as changes in the piping system, fluid properties, or operating conditions. It is important to regularly monitor and update the system head curve to ensure the pump is operating at its optimal point and to avoid any potential performance issues.

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