Air - Humidifying with Steam - Imperial Units
Estimate the amount of steam required (lb/h in 100 cfm) in humid air.
The amount of steam needed to humidify 100 cfm (cubic feet per minute) of air is indicated below.
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| Vapor in 100 cfm air (lb/h) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry Temperature | Humidity (%) | |||||||||||||
| (oF) | (oC) | 100 | 85 | 80 | 75 | 70 | 65 | 60 | 55 | 50 | 45 | 40 | 35 | 30 |
| 90 | 32.2 | 12.8 | 10.9 | 10.3 | 9.6 | 9.0 | 8.3 | 7.7 | 7.1 | 6.4 | 5.8 | 5.1 | 4.5 | 3.9 |
| 88 | 31.1 | 12.1 | 10.3 | 9.7 | 9.1 | 8.5 | 7.9 | 7.3 | 6.6 | 6.1 | 5.4 | 4.8 | 4.2 | 3.6 |
| 86 | 30.0 | 11.4 | 9.7 | 9.1 | 8.5 | 8.0 | 7.4 | 6.9 | 6.3 | 5.7 | 5.1 | 4.6 | 4.0 | 3.4 |
| 85 | 29.4 | 11.0 | 9.4 | 8.8 | 8.3 | 7.7 | 7.2 | 6.6 | 6.1 | 5.5 | 5.0 | 4.4 | 3.9 | 3.3 |
| 84 | 28.9 | 10.7 | 9.1 | 8.5 | 8.0 | 7.5 | 7.0 | 6.4 | 5.9 | 5.3 | 4.8 | 4.3 | 3.7 | 3.2 |
| 83 | 28.3 | 10.4 | 8.8 | 8.3 | 7.8 | 7.3 | 6.7 | 6.2 | 5.7 | 5.2 | 4.7 | 4.2 | 3.6 | 3.1 |
| 82 | 27.8 | 10.1 | 8.6 | 8.0 | 7.6 | 7.1 | 6.5 | 6.1 | 5.5 | 5.0 | 4.5 | 4.0 | 3.5 | 3.0 |
| 81 | 27.2 | 9.8 | 8.3 | 7.8 | 7.3 | 6.8 | 6.4 | 5.9 | 5.4 | 4.9 | 4.4 | 3.9 | 3.4 | 2.9 |
| 80 | 26.7 | 9.5 | 8.0 | 7.6 | 7.1 | 6.7 | 6.2 | 5.7 | 5.2 | 4.7 | 4.3 | 3.8 | 3.3 | 2.8 |
| 79 | 26.1 | 9.2 | 7.8 | 7.3 | 6.9 | 6.4 | 6.0 | 5.5 | 5.1 | 4.6 | 4.1 | 3.7 | 3.2 | 2.7 |
| 78 | 25.6 | 8.9 | 7.6 | 7.1 | 6.7 | 6.2 | 5.8 | 5.3 | 4.9 | 4.4 | 4.0 | 3.6 | 3.1 | 2.7 |
| 77 | 25.0 | 8.6 | 7.3 | 6.9 | 6.5 | 6.1 | 5.6 | 5.2 | 4.7 | 4.3 | 3.9 | 3.5 | 3.0 | 2.6 |
| 76 | 24.4 | 8.4 | 7.1 | 6.7 | 6.3 | 5.9 | 5.5 | 5.0 | 4.6 | 4.2 | 3.8 | 3.4 | 2.9 | 2.5 |
| 75 | 23.9 | 8.1 | 6.9 | 6.5 | 6.1 | 5.7 | 5.3 | 4.9 | 4.5 | 4.1 | 3.6 | 3.2 | 2.8 | 2.4 |
| 74 | 23.3 | 7.9 | 6.7 | 6.3 | 5.9 | 5.5 | 5.1 | 4.7 | 4.3 | 3.9 | 3.5 | 3.1 | 2.7 | 2.4 |
| 73 | 22.8 | 7.6 | 6.5 | 6.1 | 5.7 | 5.3 | 4.9 | 4.6 | 4.1 | 3.8 | 3.4 | 3.1 | 2.7 | 2.3 |
| 72 | 22.2 | 7.4 | 6.3 | 5.9 | 5.5 | 5.2 | 4.8 | 4.4 | 4.1 | 3.7 | 3.3 | 2.9 | 2.6 | 2.2 |
| 71 | 21.7 | 7.1 | 6.1 | 5.7 | 5.3 | 5.0 | 4.6 | 4.3 | 3.9 | 3.6 | 3.2 | 2.9 | 2.5 | 2.1 |
| 70 | 21.1 | 6.9 | 5.9 | 5.5 | 5.4 | 4.8 | 4.5 | 4.1 | 3.8 | 3.5 | 3.1 | 2.8 | 2.4 | 2.1 |
| 69 | 20.6 | 6.7 | 5.7 | 5.4 | 5.0 | 4.7 | 4.4 | 4.0 | 3.7 | 3.4 | 3.0 | 2.7 | 2.4 | 2.0 |
| 68 | 20.0 | 6.5 | 5.5 | 5.2 | 4.9 | 4.5 | 4.2 | 3.9 | 3.5 | 3.2 | 2.9 | 2.6 | 2.3 | 1.9 |
| 67 | 19.4 | 6.2 | 5.3 | 5.0 | 4.7 | 4.4 | 4.1 | 3.7 | 3.4 | 3.1 | 2.8 | 2.5 | 2.2 | 1.9 |
| 66 | 18.9 | 6.1 | 5.2 | 4.9 | 4.5 | 4.2 | 3.9 | 3.6 | 3.3 | 3.0 | 2.7 | 2.4 | 2.1 | 1.8 |
| 65 | 18.3 | 5.9 | 5.0 | 4.7 | 4.4 | 4.1 | 3.8 | 3.5 | 3.2 | 2.9 | 2.6 | 2.3 | 2.1 | 1.8 |
| 60 | 15.6 | 5.0 | 4.2 | 4.0 | 3.7 | 3.5 | 3.2 | 3.0 | 2.7 | 2.5 | 2.2 | 2.0 | 1.7 | 1.5 |
| 55 | 12.8 | 4.2 | 3.6 | 3.4 | 3.1 | 2.9 | 2.7 | 2.5 | 2.3 | 2.1 | 1.9 | 1.7 | 1.5 | 1.3 |
| 50 | 10.0 | 3.5 | 3.0 | 2.8 | 2.6 | 2.5 | 2.3 | 2.11 | 1.9 | 1.8 | 1.6 | 1.4 | 1.2 | 1.1 |
| 45 | 7.2 | 2.9 | 2.5 | 2.4 | 2.2 | 2.1 | 1.9 | 1.8 | 1.6 | 1.5 | 1.3 | 1.2 | 1.0 | 0.89 |
| 40 | 4.4 | 2.5 | 2.1 | 2.0 | 1.8 | 1.7 | 1.6 | 1.5 | 1.3 | 1.2 | 1.1 | 1.0 | 0.86 | 0.74 |
| 30 | -1.1 | 1.7 | 1.4 | 1.3 | 1.2 | 1.2 | 1.1 | 1.0 | 0.92 | 0.83 | 0.75 | 0.67 | 0.58 | 0.50 |
| 20 | -6.7 | 1.1 | 0.91 | 0.85 | 0.80 | 0.75 | 0.70 | 0.64 | 0.59 | 0.53 | 0.48 | 0.43 | 0.37 | 0.32 |
| 10 | -12.2 | 0.67 | 0.56 | 0.53 | 0.50 | 0.47 | 0.43 | 0.40 | 0.37 | 0.33 | 0.30 | 0.26 | 0.23 | 0.20 |
| 0 | -17.8 | 0.41 | 0.35 | 0.32 | 0.31 | 0.29 | 0.26 | 0.25 | 0.22 | 0.20 | 0.19 | 0.16 | 0.13 | 0.12 |
| -10 | -23.3 | 0.25 | 0.21 | 0.2 | 0.19 | 0.17 | 0.16 | 0.15 | 0.14 | 0.12 | 0.11 | 0.10 | 0.08 | 0.08 |
| -20 | -28.9 | 0.14 | 0.12 | 0.11 | 0.11 | 0.10 | 0.10 | 0.08 | 0.08 | 0.72 | 0.06 | 0.05 | 0.05 | 0.04 |
- 100 cfm = 0.047 m3/s = 170 m3/h
- 1 lb/h = 0.4536 kg/h
Example - Humidifying Air with Steam
How much steam is needed to transform air at 30 oF with 100% humidity to air at 70 oF with 40% humidity?
- air at 30 oF and 100% humidity - steam content 1.67 lb/h (100 cfm/h air flow)
- air at 70 oF and 40% humidity - steam content 2.76 lb/h (100 cfm/h air flow)
The difference (2.76 - 1.67) = 1.09 lb/h is the amount of steam needed for 100 cfm/h air flow.
Note!
This table neglects the sensible heat required to heat cold air to final state. In the example above the heat required to heat 100 cfm dry air from 30 oF to 70 oF must be added. The heat can be added as dry heat with heating panels or similar, or in general more convenient by adding more steam.
