Undergrad Interpreting Thermal Power in Cylinder with Source & Sink

[George444fg]

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

 

[russ_watters]

I really don't understand your question. What is there to interpret? What does "thirsty" mean/add to the description?

 

[George444fg]

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

 

[russ_watters]

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?

 

[George444fg]

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 celsius. (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?

 

[russ_watters]

I know that at the boundary the temperature is 10 celsius. (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.