Dynamic modeling of a system and transients of the system

In summary: Conservation of mass: The mass in the tank is always equal to the mass out. Energy: The energy in the tank is always equal to the energy out. Volume: The volume of the tank is always equal to the volume of the gas that was put in.The perfect gas law: PV=NRTThis tells us that the pressure, volume, and temperature are always constant.
  • #1
Nikhil N
81
2
Consider, I have a dynamic system model for air compressor. Which means I have modeled the system by including its physics. Does this means I also included the transients of the system?
What I think is, when i modeled any system with equations, I think that includes the transients. Is it correct?

I want to know how can I model a pneumatic tank with equations in matlab?
 
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  • #2
Nikhil N said:
What I think is, when i modeled any system with equations, I think that includes the transients. Is it correct?

Not necessarily. You could model it by saying mass in equals mass out. That is simply conservation of mass, a very important equation. But that model is too simple to include transients.

The key question you need is "are the equations differential equations?"
 
  • #3
anorlunda said:
Not necessarily. You could model it by saying mass in equals mass out. That is simply conservation of mass, a very important equation. But that model is too simple to include transients.

The key question you need is "are the equations differential equations?"
That means, if the system modeled with differential equations will includes the transients. Isn't it?
 
  • #4
Nikhil N said:
That means, if the system modeled with differential equations will includes the transients. Isn't it?

Yes, but to be careful with words, only if the differentials are with respect to time. It is possible to have partial differential equations that do not include time. We don't use the word transients to describe their solutions.

Then you need one more thing for a transient simulation. You need the time behavior of the boundary conditions.

It makes me nervous to provide these answers because it sounds like you don't really understand what transient simulation means.
 
  • #5
Simply having time differential equations does not necessarily mean that you have correctly included the transient. As a simple example, if you describe the dynamics of a simple spring-mass system but do not include the damping, you will get an undamped solution; this does not decay and thus has no transition into steady state. It is only when you get the complete system model that you have all of the intransigent behavior.
 
  • #6
anorlunda said:
Yes, but to be careful with words, only if the differentials are with respect to time. It is possible to have partial differential equations that do not include time. We don't use the word transients to describe their solutions.

Then you need one more thing for a transient simulation. You need the time behavior of the boundary conditions.

It makes me nervous to provide these answers because it sounds like you don't really understand what transient simulation means.
I mean differential equation w.r.t time only. I have an idea, what is transient behaviour is.
 
  • #7
Can anybody help to derive a mathematical model of an air storage tank for an air compressor system?

I have a scew type compressor(fixed speed type), which will deliver 1000cfm to a storage tank. The output for end use require 80-90psi. But the load(air flow output from tank) is varying w.r.t time, I need to include these all cases in consideration in the model. I think I may have to add a valve too after the storage tank. Anybody has any idea how to do this?
 
Last edited:
  • #8
Nikhil N said:
Anybody has any idea how to do this?

Of course, you start with the first principles: conservation of mass, energy, volume, and the perfect gas law. But we can't do your work for you. Post your equations and a diagram and we can offer comments on it.
 

1. What is dynamic modeling and why is it important?

Dynamic modeling is the process of creating a mathematical representation of a system that changes over time. This allows scientists to study how the system behaves under different conditions and make predictions about its future behavior. It is important because it allows us to better understand complex systems and make informed decisions about them.

2. How is a dynamic model created?

A dynamic model is typically created by first identifying the key components and variables of the system and their relationships. This information is then translated into mathematical equations and simulated using computer software. The model is then refined and adjusted based on real-world data to improve its accuracy.

3. What are transients in a dynamic system?

Transients are temporary changes or disturbances in a dynamic system that occur due to external factors or changes in the system itself. These changes can have a significant impact on the behavior of the system and can be studied using dynamic modeling to understand how the system responds to them.

4. How are transients analyzed in a dynamic model?

Transients are often analyzed by simulating the system under different conditions and observing how it responds to the changes. This can help scientists identify potential issues or predict the behavior of the system in different scenarios. Sensitivity analysis can also be used to determine the impact of specific variables on the system's behavior during transients.

5. What are the real-world applications of dynamic modeling and transient analysis?

Dynamic modeling and transient analysis have a wide range of applications in various fields, including engineering, economics, and environmental science. They can be used to design and optimize systems, predict and prevent potential problems, and inform decision-making processes. For example, dynamic modeling can be used to study the effects of climate change on a particular ecosystem or to optimize the design of a power grid to handle fluctuations in energy demand.

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