Need Help with Thermo Energy Transfer problem

In summary, the conversation discusses the transfer of energy through a 0.2-m-thick concrete wall at steady state. The energy transfer rate by conduction through a 1-m^2 area of the wall is 0.15 kW. Using Fourier's law, the conversation tries to determine the temperature difference across the wall, but becomes stuck due to confusion about heat flux and the transfer coefficient for concrete.
  • #1
jcamp11
4
0
A 0.2-m-thick plane wall is constructed of concrete. At steady state the energy transfer rate by conduction through a 1-m^2 area of the wall is 0.15 kW. If the temperature distibution is linear through the wall, what is the temperature difference across the wall, in K?

i don't even know where to start, anything will help...
 
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  • #2
I have been doing some work on this.. and i have came up with an answer, I am pretty sure its not right though..

Using Fourier's law:

Qx= -kA[T2-T1/L]

we know that the Qx is .15kW per 1 m^2, and the thickness of the concrete plane is .2 m

If .15kW of energy enter 1.0 m^2, then only .03 kW enter the area of .2 m??

right now i have .03kW= -k(T2-T1/ .2m)

im stuck..
 
  • #3
If .15kW of energy enter 1.0 m^2, then only .03 kW enter the area of .2 m??

Why is this? I don't think you understand the concept of "heat flux" which you represent as Qx. Heat flux is the rate of heat transferred given an area. In math form thats

q" = [tex]\frac{dQ}{dt}[/tex] = Qx

So if you have 0.15kw of energy being transferred over 1m^2 of area, what is your heat flux going to be?

You are also going to need to look up the transfer coefficient (k) for concrete. I imagine this is in your book somewhere.
 

1. What is thermo energy transfer?

Thermo energy transfer is the process of transferring heat or thermal energy from one object to another. This can occur through conduction, convection, or radiation.

2. What factors affect thermo energy transfer?

The rate of thermo energy transfer is affected by the temperature difference between the two objects, the thermal conductivity of the materials involved, and the surface area of contact between the objects.

3. How is thermo energy transfer measured?

Thermo energy transfer is measured using units of energy, such as joules or calories. The amount of heat transferred can be calculated using the equation Q=mcΔT, where Q is the amount of heat transferred, m is the mass of the object, c is the specific heat capacity of the material, and ΔT is the change in temperature.

4. What are some real-life applications of thermo energy transfer?

Thermo energy transfer is a fundamental process that occurs in various everyday situations, such as cooking food on a stove, heating a room with a radiator, or feeling the warmth of the sun on your skin. It is also crucial in industrial processes, such as power generation and refrigeration.

5. How can thermo energy transfer be controlled or enhanced?

Thermo energy transfer can be controlled or enhanced by using insulating materials to reduce heat loss, increasing the surface area of contact between objects, or using devices such as heat exchangers to transfer heat more efficiently.

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