Heat flow through composite material

In summary, The conversation discusses a problem involving a composite wall with varying thermal conductivities and heat transfer coefficients on each side. The challenge lies in correctly setting up the thermal circuit and making assumptions about 1D vs 2D heat flow. The speaker also expresses frustration with their professor's lack of expertise.
  • #1
gfd43tg
Gold Member
950
50

Homework Statement


The cross section of a 20 cm thick, 3 m wide, and 1 m high composite wall is shown. The conductivities of materials A, B and C are 1.0, 0.1, and 0.05 W m-1 K-1, respectively. One side is exposed to air at 295 K with a heat transfer coefficient of 4 W m-2 K-1, and the other side is exposed to air at 260 K with a heat transfer coefficient of 16 W m-2 K-1. Estimate the heat flow through the wall. Carefully discuss any assumptions you make.

Homework Equations

The Attempt at a Solution


For this problem, my biggest concern is if I did my thermal circuit correctly. Also, is the area just the area of each composite material perpendicular to the direction of heat flow?

The reason I got 5 sections of A,B, and C is because the width is given as 3 meters, and a divide by 40+20 = 60 cm to get 5 sections, so there is a lot of parallel heat flow happening here.

ImageUploadedByPhysics Forums1413007493.822605.jpg
 

Attachments

  • 2.5 figure.PNG
    2.5 figure.PNG
    36 KB · Views: 631
Physics news on Phys.org
  • #2
You have the circuit set up correctly. But, I don't like this problem. Why? Because if you assume 1D heat flow, the temperature profile through the A's will be different from the temperature profile through the BC's. Just calculate the temperature at the center of A, and also calculate the temperature at the boundary between B and C. You will get different numbers. In order to solve this as a 1D heat conduction problem, you need to assume that there is insulation at the boundaries between the A's and the BC's. Otherwise the heat flow will be 2D.

Chet
 
  • Like
Likes gfd43tg
  • #3
Doesn't surprise me that my professor doesn't know what she is doing, I got that impression from the get-go!
 

Related to Heat flow through composite material

1. What is a composite material?

A composite material is a material made up of two or more distinct materials that are combined to create a new material with unique properties. This can include materials such as polymers, metals, ceramics, and carbon fibers.

2. How does heat flow through composite materials?

Heat flow through composite materials is determined by the thermal conductivity of the individual materials and the arrangement of those materials within the composite. The direction and rate of heat flow can also be affected by the presence of interfaces and any thermal barriers present.

3. How does the thermal conductivity of composite materials compare to that of individual materials?

The thermal conductivity of composite materials is typically lower than that of individual materials. This is because the interfaces and boundaries between the different materials in a composite act as barriers to heat flow, reducing the overall thermal conductivity of the material.

4. What factors affect the thermal conductivity of composite materials?

The thermal conductivity of composite materials is affected by factors such as the composition and arrangement of the materials, the presence of interfaces and boundaries, and the temperature and pressure conditions. The type and amount of filler materials, such as fibers or particles, can also impact the thermal conductivity of a composite.

5. How can the thermal conductivity of composite materials be measured?

The thermal conductivity of composite materials can be measured using techniques such as the hot disk method, which involves applying heat to one side of the material and measuring the temperature on the other side. Other methods include laser flash analysis and steady-state heat flow measurements.

Similar threads

Engineering Water Flow from Pressurized Tank through Heat Exchanger
    • Engineering and Comp Sci Homework Help
2
Replies
56
Views
3K
Spec'ing the power of heater for an atypical heat exchanger problem
    • Engineering and Comp Sci Homework Help
Replies
22
Views
2K
Engineering Tubular Reactor with catalytic walls
    • Engineering and Comp Sci Homework Help
Replies
6
Views
844
Engineering Heat transfer from composite pipe -- Is my answer right?
    • Engineering and Comp Sci Homework Help
Replies
1
Views
979
Temperature after closing the valve
    • Engineering and Comp Sci Homework Help
Replies
8
Views
1K
Liquid ammonia is heated as it flows at a mean velocity of 2
    • Engineering and Comp Sci Homework Help
Replies
13
Views
2K
Engineering Average heat transfer coefficient (forced convection)
    • Engineering and Comp Sci Homework Help
Replies
6
Views
2K
Thermodynamics: help regarding the coefficient of heat transfer
    • Engineering and Comp Sci Homework Help
Replies
7
Views
1K
Flow inside pipe, heat transfer
    • Engineering and Comp Sci Homework Help
Replies
15
Views
2K
Engineering Calculate valve sizing to regulate the flow of natural gas
    • Engineering and Comp Sci Homework Help
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top