Superheated Steam - Entropy
The entropy of steam superheated to temperatures above saturation points.
The entropy of superheated steam at different pressures and temperatures are indicated below:
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| Absolute Pressure | Saturation Temperature | Entropy (kJ/kgK) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Steam Temperature (oC) | |||||||||
| (kPa) | (bar) | (oC) | 120 | 150 | 180 | 200 | 230 | 250 | 280 |
| 150 | 1.5 | 111.4 | 7.239 | 7.419 | 7.557 | 7.644 | 7.767 | 7.845 | 7.957 |
| 200 | 2 | 120.2 | 7.279 | 7.420 | 7.507 | 7.631 | 7.710 | 7.822 | |
| 250 | 2.5 | 127.4 | 7.169 | 7.311 | 7.400 | 7.525 | 7.604 | 7.717 | |
| 350 | 3.5 | 138.9 | 6.998 | 7.146 | 7.237 | 7.364 | 7.444 | 7.558 | |
| 400 | 4 | 143.6 | 6.929 | 7.079 | 7.171 | 7.299 | 7.380 | 7.495 | |
| 500 | 5 | 151.8 | 6.965 | 7.059 | 7.190 | 7.272 | 7.388 | ||
| 600 | 6 | 158.8 | 6.869 | 6.966 | 7.100 | 7.183 | 7.300 | ||
| 700 | 7 | 165.0 | 6.786 | 6.886 | 7.022 | 7.107 | 7.225 | ||
| 800 | 8 | 170.4 | 6.712 | 6.815 | 6.954 | 7.040 | 7.156 | ||
| 900 | 9 | 175.4 | 6.645 | 6.751 | 6.893 | 6.980 | 7.101 | ||
| 1000 | 10 | 179.9 | 6.584 | 6.692 | 6.838 | 6.926 | 7.049 | ||
| 1100 | 11 | 184.4 | 6.638 | 6.787 | 6.876 | 7.001 | |||
| 1200 | 12 | 188.0 | 6.587 | 6.739 | 6.831 | 6.956 | |||
| 1400 | 14 | 195.0 | 6.494 | 6.653 | 6.748 | 6.877 | |||
| 1600 | 16 | 201.4 | 6.577 | 6.674 | 6.806 | ||||
| 2000 | 20 | 212.4 | 6.440 | 6.546 | 6.685 | ||||
| 2500 | 25 | 223.9 | 6.292 | 6.407 | 6.558 | ||||
| 3500 | 35 | 242.5 | 6.173 | 6.349 | |||||
If saturated steam is exposed to a surface with a higher temperature the temperature of the steam will increase above the evaporating temperature. The steam is then described as superheated by the temperature degrees above saturation temperature.
- Note! Steam cannot be superheated whilst it is still in the contact with water, because additional heat will evaporate more water, cooling down the superheated steam.
Superheated steam is produced by passing saturated steam through an additional heat exchanger.
Superheated steam is also called
- surcharged steam
- anhydrous steam
- steam gas
