Carnegie Mellon

Mechanical Engineering

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FEM/ANSYS

## Test T2: Heat Flux of Composite Model

Thermal Test #2: Heat flux analysis of a composite model

Introduction: In this example you will show your ability to model composite models.

Physical Problem: Most people have at one time or another experienced a frigid climate. The best way to stay warm is by way of layers. In this problem we will model a section of layering as a wall and determine the temperature gradient through components. This gives an estimate of the amount of heat that the body needs to supply to maintain comfort inside, as well as the limitations of the clothes (and reasons for searching out higher quality layers).

Problem Description:

The outer material of the composite wall is steel with thermal conductivity of 20 W/m K

The insulating material has a thermal conductivity of 0.1 W/m K.

Units: Use S.I. units ONLY

Geometry: See figure.

Boundary Conditions:
 Conductivities: PINK LAYER Skin                                                                      2.75 (estimate) FIRST LAYER Undergarments (Such as cotton)                            0.04 SECOND LAYER Fleece (polyester)                                              0.05 OUTSIDE LAYER Overcoat (fur or equally insulating material)        0.024 The bulk temperature outside is 273K. Your body generates heat and we are going to estimate a skin temperature of 310.1 K Intermediate layers are AIR  with conductivity = 0.021

Objective:
 To determine the heat flux through the layers. To plot the temperature distribution.

You are required to hand in print outs for the above.

Figure:

UNITS ARE MILLIMETERS

·         Create the key points defining the vertices of all the layers. (skin thickness, undershirt, air, fleece, air, coat)

·         Connect the key points to form lines, then connect lines to form the respective areas.

·         Define the Material Properties of the Air Element (Thermal Conductivity for each layer needs to be set.)

·         Set the temperatures to Fahrenheit instead of Celsius.

·         Define the Element Properties as two Quad 8node 77 thermal solids.

·         Mesh the figure with a mesh size of 0.01 on all the lines defining the each layer. (Be sure to mesh each material separately such that the material properties are set independently of each other.)

·         Apply Boundary Conditions (Constant temperature on the skin, and the outer layer of the coat.)

·         Solve

·         List the nodal temperature distribution in the X and Y directions, below is the answer you should obtain.

·         Plot the nodal temperature distribution in the X and Y directions, below is the answer you should obtain:

(The nodal displacements will be listed as follows:)

(The temperature distribution will look like this:)