Laird be 4120 project presentation working
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Transcript of Laird be 4120 project presentation working
Why? Observations – uniforms cause members to feel
extremely warm – heat exhaustion is common
Winter time – acts as extra layer of clothing, often have
to wear many layers
How much does the uniform actually affect this?
Solving Analytically
0. See right
1. Human, with and
without uniform
2. Flat plate
3. x direction – assumed to be width (front to back)
4. Assume no bulk flow in/out; heat transfer by conduction
and free convection at surface
Credit for image: Tiger Band Media
Continued 5. BC 1: Convection at surface:
BC 2: Symmetrical temperature profile assumed:
6. Heat generation – assume constant for relative time
frame
7. Thermal conductivity (k) assumed constant
8. Assumed steady state (short time frame)
9.
10. Solve for unknown – temperature at surface of skin with
and without uniform (for all work, see Appendix)
Final equation:
Solution Analytically – without: 24.6°C; with: 24.8°C
Numerically – used COMSOL model
W/o – theoretically says 37°C
W/ - range of ~304-311 K (31-38 °C), Average = 34.5 °C
Experimentation Measured temperature near surface of skin for 30
minutes without uniform and 30 minutes with
Outside temperature: roughly 22-23°C (measured
simultaneously)
Cloudy conditions – disregard solar radiation in
analysis
Used HOBO Data loggers
Imported data and graphed
Figure 1. Temperatures
logged for outside air
(average), and near skin
with and without uniform.
Figure 2. Relative humidity
logged with and without
uniform.
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35
Tem
pera
ture
[C
]
Time Passed [min]
Without Uniform
With Uniform
Air Temperature
39
40
41
42
43
44
45
46
47
48
0 10 20 30 40
Rela
tiv
e H
um
idit
y [
%]
Time Passed [min]
Without Uniform
With Uniform
Conclusions Final results:
Analytically – 24.8°C (76.6°F) with uniform
Numerical – 34.5°C (94.1°F) with uniform
Experimentally – ~34°C (93°F) with uniform
Increase of ~4°C (7.2°F) with uniform
Numerical & Experimental – 1.5% difference
Averaged COMSOL values, experimental factors
Experimental & analytical – 27% difference
Assumptions made, different method of solving, experimental factor
Special thanks to: Tiger Band for the loan of the uniform
Dr. Caye Drapcho for teaching us this material, and her
aid to me in this project
Jeremiah Davis for help with the HOBOs
https://twitter.com/cutigerband
http://www.clemson.edu/majors/biosystems-engineering
ReferencesDrapcho, Caye. “Lecture 4: Modes of Heat Transfer.” BE 4120. Clemson University,
Clemson. 26 January 2015. Lecture.
Drapcho, Caye. “Lecture 5: SS conduction/convection.” BE 4120. Clemson University,
Clemson. 28 January 2015. Lecture.
Drapcho, Caye. “Lecture 6: SS conduction/convection.” BE 4120. Clemson University,
Clemson. 4 February 2015. Lecture.
Drapcho, Caye. “Lecture 8: Heat Diffusion Equation.” BE 4120. Clemson University,
Clemson. 9 February 2015. Lecture.
Drapcho, Caye. “Lecture 9: Boundary Conditions.” BE 4120. Clemson University,
Clemson. 11 February 2015. Lecture.
Drapcho, Caye. “Lecture 15: Free convection.” BE 4120. Clemson University,
Clemson. Date. Lecture.
Drapcho, Caye. “Introduction to COMSOL.” BE 4120. Clemson University, Clemson.
13 February 2015. Lecture.
Nave. 2014. Thermal Conductivity. HyperPhysics. Georgia State University. Available
at: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/thrcn.html. Accessed
12 April 2015.
Specific Heat. The Engineering Toolbox. Available at:
http://www.engineeringtoolbox.com/specific-heat-solids-d_154.html.
Accessed 11 April 2015.
2015. Polyethylene Terephthalate. Wikipedia. Wikipedia. Available at:
http://en.wikipedia.org/wiki/Polyethylene_terephthalate. Accessed 11 April
2015.
2015. Wool: density in 285 measurement units. Aqua-Calc. AVCalc LLC. Available at:
http://www.aqua-calc.com/page/density-table/substance/wool. Accessed
11 April 2015.