Solving Basic Thermo Questions: Calculating Velocity and Area in an Open System

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In summary, the conversation discusses how to calculate the velocity and area for an open system with mass flow rate going into one inlet and going through two outlets. The equation 0 = h1 – h2 + (V1^2– V2^2)/2 is suggested for finding the velocity, and it is confirmed that a third term can be plugged in with the presence of two outlets. The formula for the area is also provided, using the mass flow rate and density of the inlet. This approach is deemed correct.
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rjenkins
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I have question (probably figured that). I have an open system with mass flow rate going into one inlet and going through two outlets. I have all the terms for the two outlets (mass flow, velocity, area, temp, pressure). However for the inlet I'm missing the Velocity and Area.

In solving for the Velocity I figured I could you use the following equation

0 = h1 – h2 + (V1^2– V2^2)/2

But being I have two outlets in this case can I just plug in a 3rd term?

0 = h1 – h2 – h3 + (V1^2– V2^2 – V3^2)/3
 
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So for the inlet velocity I get:V3^2 = 3(h1 – h2 – h3) + (V1^2– V2^2) And then for the area:A3 = M3/(V3*ρ3) Where M3 is the mass flow rate of the inlet and ρ3 is the density of the inlet. Is this the correct approach? Yes, this is the correct approach. To calculate the velocity of the inlet, you can use the equation given above. And for the area, you can use the equation you provided.
 
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Yes, you can definitely use a third term in the equation to account for the additional outlet. The equation you are using is known as the Bernoulli's equation, which is commonly used to calculate the velocity of a fluid in an open system. In this case, you are solving for the velocity at the inlet, so you will need to include all the relevant terms for the inlet and the two outlets.

However, it is important to note that this equation assumes that the fluid is incompressible and there is no energy loss in the system. So, it may not give you an accurate result if these assumptions do not hold true in your system. It is always a good practice to check the validity of the assumptions before using any equation.

Additionally, you will also need to consider the continuity equation, which states that the mass flow rate at the inlet must be equal to the sum of the mass flow rates at the outlets. This will help you in solving for the missing area at the inlet.

Overall, it is important to carefully consider all the relevant equations and assumptions before solving thermo questions in an open system. I would also recommend double-checking your calculations and units to ensure an accurate result.
 

FAQ: Solving Basic Thermo Questions: Calculating Velocity and Area in an Open System

What is thermodynamics?

Thermodynamics is the branch of science that deals with the study of energy and its transformations, including heat and work. It also describes how energy is transferred between systems and how it affects the properties of matter.

What are the laws of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. The second law states that the total entropy of a closed system will never decrease over time. The third law states that the entropy of a perfect crystal at absolute zero temperature is zero.

How is temperature related to energy?

Temperature is a measure of the average kinetic energy of the particles in a substance. As the temperature increases, the particles gain more energy and move faster, while at lower temperatures, the particles have less energy and move slower.

What is the difference between heat and work?

Heat is the transfer of energy between systems due to a temperature difference. It is a form of energy that is not able to do work. Work, on the other hand, is the transfer of energy that results in a change in the state or motion of a system.

What is an example of a thermodynamic process?

An example of a thermodynamic process is the Carnot cycle, which is a theoretical cycle that describes the most efficient way to convert heat into work. It consists of two isothermal processes (constant temperature) and two adiabatic processes (no heat transfer).

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