Steam calculations and correction factors – Sterling HS User Manual
Page 6
6
EXAMPLE: –
UNIT SIZE: _________ 24
Steam Pressure ___10 PSI
Entering Air Temp. __ 40°F
I. CAPACITY
A. For 2 lbs. steam, 60° entering air
Read output directly from Table 3, 24,000 BTU/HR.
(Ref., Std. 24).
B. For higher steam pressures
Multiply output from Table 3 by appropriate correction
and/or E.A.T.’s above or below 60°F
factor from Table 4 (below).
24,000 x 1.29 = 30,960 BTU/HR.
II. FINAL AIR TEMPERATURE
A. For 2 lbs. steam, 60° entering air
Read temperature directly from Table 3, 109°F.
(Ref., Std. 24).
B. For capacities calculated in I.B. (above)
Output from I.B.
+ E.A.T. = Final Air Temp.
30,960
+ 40 = 103.4°F.
1.085 x CFM from Table 3
1.085 x 450
III. FINAL AIR VOLUME
Nom. CFM Final
A. For 2 lbs. steam, 60° entering air
460 + Final Air Temp from Table 3
x
from = Air
460+109
x 450 = 483 CFM
530 Table 3 Volume
530
Nom. CFM Final
B. For fi nal air temperatures calculated
460 + Final Air Temp from II.B.
x
from = Air
460+103.4
x 450 = 478 CFM
In II. B. (above)
530 Table 3 Volume
530
IV. CONDENSATE PER HOUR
Read lbs. per hour from Table 3, 24.5 LBS./HR.
A. For 2 lbs. steam, 60° entering air
(Ref., Std. 24).
B. For capacities calculated in I.B. (above)
Output from I.B.
= lbs. per hour of condensate
30,960
= 32.5 LBS./HR.
Latent Heat From Table 5
953
30 -(1)
40 (4)
50 (10)
60 (16)
70 (21)
80 (27)
90 (32)
100
(38)
STEAM PRESSURE (SATURATED) — LBS. PER SQ. IN. (kPa)
STEAM PRESSURE IN PSIG (kPa)
15
(103.4)
249.8
(121.0)
946
(2200)
2
(13.8)
218.5
(103.6)
966
(2247)
10
(68.9)
239.4
(115.2)
953
(2217)
Steam Pressure
psi (kPa)
Steam Temperature
Deg. F (Deg. C)
Latent Heat of Steam
Btu/lbm (KJ/Kg)
0
(0)
212
(100)
970
(2256)
15
(103.4)
1.44
1.34
1.28
1.19
1.12
1.04
0.97
0.89
5
(34.5)
1.29
1.21
1.13
1.05
0.97
0.90
0.83
0.76
2
(13.8)
1.24
1.16
1.08
1.00
0.93
0.85
0.78
0.71
ENTERING AIR
TEMPERATURE
Deg. F (Deg. C)
10
(68.9)
1.38
1.29
1.21
1.13
1.06
0.98
0.91
0.84
TABLE 4 — STEAM CORRECTION FACTORS BASED ON
2 PSI (13.8 kPa) STEAM AND 60 Deg. F (16 Deg. C) E.A.T.
0
(0)
1.19
1.11
1.03
0.96
0.88
0.81
0.74
0.67
TABLE 5 — PROPERTIES OF SATURATED STEAM
STEAM CALCULATIONS AND CORRECTION FACTORS
5
(34.5)
227.1
(108.4)
961
(2235)
20
(137.9)
1.50
1.42
1.33
1.25
1.17
1.10
1.02
0.95
30
(206.8)
1.60
1.51
1.43
1.35
1.27
1.19
1.12
1.04
40
(275.8)
1.68
1.60
1.51
1.43
1.35
1.27
1.19
1.12
50
(344.7)
1.70
1.66
1.58
1.50
1.42
1.34
1.26
1.19
75
(517.1)
1.90
1.81
1.72
1.64
1.55
1.47
1.39
1.32
30
(206.8)
274.0
(134.4)
929
(2161)
50
(344.7)
297.7
(147.6)
912
(2121)
75
(517.1)
319.9
(159.9)
891
(2072)
40
(275.8)
286.7
(141.5)
920
(2140)
20
(137.9)
258.8
(126.0)
940
(2186)
100
(689.4)
2.02
1.93
1.84
1.75
1.66
1.58
1.50
1.42
125
(861.8)
2.11
2.02
1.93
1.84
1.76
1.68
1.59
1.51
150
(1,034.1)
2.20
2.11
2.02
1.93
1.84
1.76
1.67
1.59
125
(891.8)
352.9
(178.3)
868
(2019)
150
(1,034.1)
365.9
(185.5)
857
(1993)
100
(689.4)
337.9
(169.9)
881
(2049)