Pressure drops and Temperature changes

In summary, the conversation discusses a fluid going through a pressure drop and its temperature change at a given pressure and temperature. The fluid can be either methanol or oil, and the question is how much the temperature will cool down. One suggestion is to compare pressure vs. temperature charts for water, as it may be harder to heat up than methanol or oil. Additionally, the temperature rise in a throttle can be found by noting that the fluid maintains its total enthalpy and using the specific heat of an incompressible fluid.
  • #1
hpcycling2010
1
0
Hello,

I have a fluid that is going through a pressure drop (3500psi down to atmospheric) and its around 120C at the upstream temp.
The fluid can be either methanol or oil.
What kind of temperature change will I see? I am assuming it will cool down, but by how much?

Help! and Thanks ahead of time!
 
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  • #2
I have no idea. However, I know that pressure vs. temperature charts for water are quite common and that you might be able to make some meaningful comparisons between them. I would assume that water is harder to heat up than both methanol or oil.
 
  • #3
hpcycling2010 said:
Hello,

I have a fluid that is going through a pressure drop (3500psi down to atmospheric) and its around 120C at the upstream temp.
The fluid can be either methanol or oil.
What kind of temperature change will I see? I am assuming it will cool down, but by how much?

Help! and Thanks ahead of time!

By "going through a pressure drop" do you mean a pressure drop like in a turbine, like in a nozzle, or like in a throttle? Turbines and nozzles are thermodynamically similar, but throttles are different.

If you throttle an incompressible fluid, the temperature will rise as the pressure energy converts to internal energy. You can find the temperature rise in a throttle by noting that the fluid passing through the throttle maintains its total enthalpy, h=u+P/ρ. The internal energy u=cT for an incompressible fluid, where c is the specific heat.

BBB
 

What causes pressure drops?

A pressure drop occurs when there is a decrease in the force exerted by a fluid on a surface. This can be caused by a decrease in the velocity of the fluid, an increase in the surface area, or a decrease in the density of the fluid. It can also be caused by physical obstructions or changes in the direction of flow.

How do temperature changes affect pressure drops?

Temperature changes can affect pressure drops in several ways. First, as temperature increases, the density of a gas decreases, resulting in a lower pressure. Second, temperature changes can cause changes in the viscosity of a fluid, which can affect the flow rate and pressure drop. Finally, temperature changes can also cause changes in the elasticity of a material, which can affect the pressure drop.

What is the relationship between pressure drops and flow rate?

The relationship between pressure drops and flow rate is described by the Bernoulli's principle, which states that as the flow rate increases, the pressure decreases. This means that as the fluid moves faster, there is a decrease in the force exerted on the walls of the container, resulting in a pressure drop.

How can pressure drops be measured?

Pressure drops can be measured using a pressure gauge or manometer. These devices measure the difference in pressure between two points in a system. The pressure drop can also be calculated using Bernoulli's equation, which takes into account factors such as flow rate, fluid density, and fluid velocity.

What factors can cause temperature changes in a system?

Temperature changes in a system can be caused by a variety of factors, including changes in the surrounding environment, changes in the flow rate of the fluid, and changes in the composition of the fluid. Other factors such as heat transfer, friction, and chemical reactions can also cause temperature changes.

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