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The partial pressure of water vapour in a moist air sample of relative humidity 70% is 1.6 kPa, the total pressure being 101.325 kPa. Moist air may be treated as an ideal gas mixture of water vapour and dry air. The relation between saturation temperature (Ts in K) and saturation pressure (Ps in kPa) for water is given by
in 
ps 
= 14.317 - 5304 p0 Ts
where p0 = 101.325 kPa. The dry bulb temperature of the moist air sample (in °C) is_______.
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- 15.09°C
- 20°C
- 19.89°C
- 21°C
Correct Option: C
φ = 0.7, P0 = 101.325
| φ = | ⇒ Psat = | ||
| Ps - Pw | φ |
| Psat = | = 2.28571 kPa | |
| 0.7 |
Corresponding to saturation pressure whatever is the temperature is the DBT
| In | | | = 14.317 - | ||
| P0 | Tsat |
| ln | | | = 14.317 - | - 3.7916 = 14.317 - | |||
| 101.325 | Tsat | Tsat |
| Tsat = | = 292.898 K = 19.89°C | |
| 18.1086 |
