Closed piping system question

In summary, the conversation discusses the pressure drop in a closed loop system with a constriction in the piping. It is stated that with no friction, there is no pressure drop between the inlet and outlet of the pump, but there is a pressure difference at the constriction. The conversation also mentions the use of Bernoulli's principle to calculate the pressure drop and the need for a clear definition of "no friction" in this scenario.
  • #1
Famwoor2
11
1
Hello everyone,

Say I have a closed loop comprised of a pump and some piping which connects the inlet of the pump to the outlet of the pump. All of the piping has radius "a," except for a small section, which constricts to radius "b" for a small portion of the line (the inlet and outlet connections are both of radius "a"). Neglecting friction, is there any pressure drop between the inlet and the outlet of the pump if an incompressible fluid were to flow through the system at some flow rate? If so, does Bernoulli's principle in the following fashion account for the magnitude of the pressure drop?

dP = | 1/2*(fluid density)*(flow rate)^2*(1/(pi*a^2)^2-1/(pi*b^2)^2) |

I used (flow rate) = (cross sectional area)*(flow speed) to express the flow speeds, and the fact that the flow rate is the same.

Here it is in TeX form:

[tex] \Delta P = \frac{1}{2} \rho Q^2 \left( (\frac{1}{\pi a^2})^2 - (\frac{1}{\pi b^2})^2 \right) [/tex]

Thanks for your help and time,
F2
 
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  • #2
Without any friction, there is no pressure drop between the two sides of the pump (and in an ideal system you don't need a pump at all to keep it flowing). There is a pressure difference where the cross-section changes, but the same pressure difference (in the opposite direction) occurs where the cross-section changes back.
 
  • #3
I think you need to be clear that "no friction" means not only no friction at the pipe wall, but also no friction between the fluid and itself. Otherwise the flow through the restriction will dissipate some energy by creating eddies in the flow, which would appear as heat and noise. The more gradual the approach to and exit from the restriction is, the lower these losses would be.
 
  • #4
Thanks for the feedback.
 
  • #5
Hello F2,

I can provide some insights into your question about the pressure drop in a closed piping system. Based on the information provided, it seems like you are describing a situation where a fluid is flowing through a pipe with a constriction in the middle. In this case, there will indeed be a pressure drop between the inlet and outlet of the pump.

Bernoulli's principle states that in a flow of an incompressible fluid, the total energy of the fluid remains constant. This means that as the fluid flows through the constriction, its velocity will increase, and according to the equation you provided, the pressure will decrease. This is because the cross-sectional area decreases, causing an increase in flow speed, and according to the Bernoulli equation, this results in a decrease in pressure.

To answer your question about the magnitude of the pressure drop, the equation you provided seems to be a simplified version of the Bernoulli equation, and it can be used to estimate the pressure drop in this system. However, it is important to note that this equation assumes ideal conditions, neglecting factors such as friction and turbulence, which can affect the actual pressure drop in the system.

In summary, based on the information provided, there will be a pressure drop in the closed piping system due to the constriction in the pipe. The magnitude of the pressure drop can be estimated using the equation you provided, but it may not be entirely accurate due to the simplified assumptions made. I hope this helps clarify your question.
 

What is a closed piping system?

A closed piping system refers to a network of pipes that are connected and used for the transportation of fluids or gases within a controlled environment. This means that the system is sealed and does not allow any external contaminants or substances to enter.

What are the benefits of using a closed piping system?

There are several benefits to using a closed piping system, including improved safety, increased efficiency, and reduced maintenance costs. The closed system prevents leaks and spills, which can be hazardous to both people and the environment. It also allows for better control of the flow and pressure of the fluids being transported, resulting in more efficient operations. Finally, a closed system requires less maintenance as there is no exposure to external elements that can cause damage.

How is a closed piping system different from an open piping system?

A closed piping system is different from an open system in that it is sealed and does not allow for the exchange of fluids or gases with the environment. In contrast, an open system is not sealed and allows for the exchange of fluids or gases with the environment. Closed systems are typically used for hazardous or sensitive materials, while open systems are used for non-hazardous materials.

What are some common applications of closed piping systems?

Closed piping systems are commonly used in industries such as chemical, pharmaceutical, and food processing, where strict control over the transportation of fluids or gases is necessary. They are also used in heating and cooling systems, as well as in water treatment plants and oil refineries.

How do you maintain a closed piping system?

Maintaining a closed piping system involves regular inspections and monitoring of pressure and flow rates to ensure that the system is functioning properly. Any leaks or damage should be immediately repaired, and the system should be flushed and cleaned periodically to prevent buildup and corrosion. It is also important to follow proper safety protocols and handle any hazardous materials with care.

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