PASCO TD-8564, Инструкция по эксплуатации

Страница: 9 / 28

012-05443A Thermal Efficiency Apparatus
5
by using the chart located on the front of the Thermal
Efficiency Apparatus and in Table 1. Notice that as the
temperature increases, the thermistor resistance decreases
(100 k
Ω
is a higher temperature than 200 k
Ω
).
➤
NOTE: To get the exact temperature reading
the user must interpolate between numbers on the
chart. For example, suppose the ohmmeter reads
118.7 k
Ω
. This reading lies between
120 k
Ω
= 21°C and 115 k
Ω
= 22°C. The reading is
120-118.7 = 1.3 k
Ω
above 21°C which is
1.3k
Ω ×
1
°
C
120 – 115k
Ω
= 0.26
°
C
Therefore 118.7 k
Ω
is 21.26°C.
Measurements Using the Thermal Efficiency Apparatus
Direct Measurements
Three quantities may be directly measured with the
Thermal Efficiency Apparatus: temperatures, the power
delivered to the hot reservoir, and the power dissipated by
the load resistors. The details of how these measurements
are made follow.
Temperatures
The temperatures of the hot and cold reservoirs are
determined by measuring the resistance of the thermistor
imbedded in the hot or cold block. To do this, connect an
ohmmeter to the terminals located as shown in Figure 4.
The switch toggles between the hot side and the cold side.
The thermistor reading can be converted to a temperature
461 -5
436 -4
413 -3
391 -2
370 -1
351 0
332 1
315 2
298 3
283 4
269 5
255 6
242 7
230 8
218 9
207 10
197 11
187 12
178 13
169 14
161 15
153 16
146 17
139 18
133 19
126 20
120 21
115 22
109 23
104 24
100 25
95.4 26
91.1 27
87.0 28
83.1 29
79.4 30
75.9 31
72.5 32
69.3 33
66.3 34
63.4 35
60.7 36
58.1 37
55.6 38
53.2 39
51.0 40
48.9 41
46.8 42
44.9 43
43.0 44
41.2 45
39.6 46
37.9 47
36.4 48
34.9 49
33.5 50
32.2 51
30.9 52
29.7 53
28.5 54
27.4 55
26.4 56
25.3 57
24.4 58
23.4 59
22.5 60
21.7 61
20.9 62
20.1 63
19.3 64
18.6 65
17.9 66
17.3 67
16.6 68
16.0 69
15.5 70
14.9 71
14.4 72
13.8 73
13.4 74
12.9 75
12.4 76
12.0 77
11.6 78
11.2 79
10.8 80
10.4 81
10.1 82
9.76 83
9.43 84
9.12 85
8.81 86
8.52 87
8.24 88
7.96 89
7.70 90
7.45 91
7.21 92
6.98 93
6.75 94
6.53 95
6.33 96
6.12 97
5.93 98
5.74 99
5.56 100
5.39 101
5.22 102
5.06 103
4.91 104
k
Ω
°C k
Ω
°C k
Ω
°C k
Ω
°C k
Ω
°C
Table 1: Resistance to Temperature Conversion Chart