I Interpreting Thermal Power in Cylinder with Source & Sink

AI Thread Summary
The discussion centers on the thermal dynamics of a system with two concentric cylinders, one acting as a heat source and the other as a heat sink, separated by an insulator. The internal cylinder shows positive power, indicating heat transfer to the outer cylinder, while the total system exhibits negative power, suggesting it absorbs energy from the environment. Participants clarify that the heat flow is directed from the internal cylinder to the outer cylinder, not directly to the environment. The conversation also touches on the system's steady state and the implications of temperature at the boundary. Overall, the interpretation hinges on understanding the direction of heat flow and the energy balance within the system.
George444fg
Messages
25
Reaction score
4
I have a cylinder that is separated with an insulator. In the internal cylinder there is a thermal source, while outside the insulator we have a thermal sink. The power of the internal cylinder is positive, while of the external one in total is negative. How I should interpet the results. Like the internal cylinder where the source is emits power / energy, while in total, the system absorbs energy, as the heat sink is more "thirsty"?

Thank you in advance
 
Science news on Phys.org
I really don't understand your question. What is there to interpret? What does "thirsty" mean/add to the description?
 
russ_watters said:
I really don't understand your question. What is there to interpret? What does "thirsty" mean/add to the description?
So let's be clear. I mean, I have two concentric cylinders that are separated from an insulating material. I have a heat source within the internal cylinder and heat sink outside the internal cylinder. When I calculate the power of the internal cylinder, the power is positive, while when I calculate the power of the external cylinder(that means of the whole system) it is negative. So I want, to explain the signs. The positive sign means that heat is transferred from the internal cylinder to the environment, in other words towards the heat sink, but on the contrary when we talk about the total power of the system being negative, that means that the system in general absorbs energy from the environment. I wanted to know if my explanation is correct or not. Thank you in advance
 

Attachments

  • schema_cyl.png
    schema_cyl.png
    13.3 KB · Views: 133
George444fg said:
So let's be clear. I mean, I have two concentric cylinders that are separated from an insulating material.
You mean "by" an insulating material, right?
...heat sink outside the internal cylinder.
Do you mean outside the outer cylinder?
When I calculate the power of the internal cylinder, the power is positive, while when I calculate the power of the external cylinder(that means of the whole system) it is negative. So I want, to explain the signs.

The positive sign means that heat is transferred from the internal cylinder to the environment, n other words towards the heat sink...
Not to the environment/heat sink, to the outer cylinder, right?
... but on the contrary when we talk about the total power of the system being negative, that means that the system in general absorbs energy from the environment.
How do we know that/where is it calculated? Is this system in a steady state? To me it sounds like the net energy transfer is zero, while the heat flow is positive (based on the convention you established...). Is there more to this problem you haven't said?
 
russ_watters said:
You mean "by" an insulating material, right?
Do you mean outside the outer cylinder?

Not to the environment/heat sink, to the outer cylinder, right?

How do we know that/where is it calculated? Is this system in a steady state? To me it sounds like the net energy transfer is zero, while the heat flow is positive (based on the convention you established...). Is there more to this problem you haven't said?
I know that at the boundary the temperature is 10 celcius. (Btw the comments you made are true). So I could make the assumption that : the whole system is gaining energy. In other words, the system tends to attract the heat of its vicinity to compensate a lack of energy. I am I right?
 
George444fg said:
I know that at the boundary the temperature is 10 celcius. (Btw the comments you made are true). So I could make the assumption that : the whole system is gaining energy. In other words, the system tends to attract the heat of its vicinity to compensate a lack of energy. I am I right?
Since you called the outside environment a "heat sink" I assumed that meant the heat was flowing from the outer cylinder to the environment. Is that not the case (it has to be instead state)? If so, I'd say this system is losing heat to the heat sink/ environment.
 
Back
Top