Heat Transfer from Extended Surfaces
(EDITED)
May 10, 2019
Prepared by: Nabeel Abrar
Katherine Ramirez
Gamma Industries, Inc.
Executive Summary
How does heat flow in one dimension? This particular apparatus investigated the transient and steady-state temperatures along an alloy rod. In the experiment, a rod was heated at one end over the time span of an hour. Progressively, the temperature down the length of the rod increased, this was monitored by thermocouples. The apparatus’ alloy rod consisted of several embedded thermocouples which read the temperatures at 5 cm increments along the rod length. At the very beginning of the experiment, the temperature of the rod is uniform and at room temperature which was 23.0°C, at the end of the experiment, the peak recorded temperature was 80.3°C.
Throughout the hour, the temperature readings along the rod were analyzed and recorded every five minutes. After obtaining data, comparisons are made between the theoretical steady-state distribution and experimental results for an infinitely-long fin of constant cross section. Experimental results found that the determined heat transfer coefficient for combined radiation and convection was 0.3768.
Procedure
A Hilton model H112E with eight thermocouples distributed along an alloy rod was used. In addition, a power supply and control unit was used to conduct the experiment, both seen in Figure 1. To begin, the position of each thermocouple was measured, with thermocouple 1 (TC1) being closest to the heat source was referenced as x = 0. The ninth thermocouple is attached to the base plate and is the reference for ambient room temperature which remains constant throughout the entire experiment.
The Hilton model H112E was turned on and the system conditions were set to 110 Volts with a current of 0.062 Amps. A stopwatch was started when the voltage was fixed as desired. As the alloy rod began to heat, the temperature was recorded at each thermocouple with 5 min intervals, up to 60 min. The temperature recordings over time for each thermocouple is shown in Table 1.
Figure 1. Hilton model H112E with eight thermocouples distributed along an alloy rod and voltage supply
Table 1. Thermocouple Temperature Recordings Over Time
Time (min)
Thermocouple Temperatures (°C)
TC1
TC2
TC3
TC4
TC5
TC6
TC7
TC8
TC9
0
0
0
0
0
0
0
0
0
0
5
54.0
40.8
33.5
29.0
26.6
25.5
25.0
24.8
24
10
64.5
49.0
40.2
34.0
30.1
27.9
26.8
26.3
24.3
15
70.4
53.7
44.2
37.2
32.8
30.0
28.6
27.9
24.6
20
74.0
56.8
46.8
39.3
34.6
31.6
29.9
29.2
24.8
25
76.2
58.5
48.3
40.7
35.8
32.6
31.0
30.2
25.0
30
77.5
59.5
49.2
41.5
36.6
33.3
31.6
30.8
25.2
35
78.4
60.1
49.8
41.9
37.0
33.8
32.1
31.3
25.4
40
79.1
60.6
50.3
42.4
37.5
34.1
32.5
31.7
25.5
45
79.4
61.0
50.5
42.6
37.7
34.4
32.7
31.9
25.6
50
79.6
61.0
50.6
4...
