Final answer:
The dew point is the temperature at which water vapor condenses into liquid. Given a partial pressure of water vapor, one can calculate the dew point. Relative humidity is derived from the actual vapor pressure relative to the saturation vapor pressure.
Step-by-step explanation:
The concept of dew point relates to the temperature at which water vapor in air condenses into liquid water at the same rate it evaporates. In determining the dew point of water vapor in combustion gases, one must consider the partial pressure of water vapor in the mixture. Given a partial pressure of 8.05 torr, for example, one could reference a psychrometric chart or use formulas to calculate the dew point at this pressure, considering that 760 torr is equivalent to 1 atmosphere (atm).
When considering relative humidity, it is the ratio of the current vapor pressure to the saturation vapor pressure at a given temperature. For instance, if the air temperature is 35 °C and the dew point is 25 °C, the actual partial pressure of water vapor can be calculated based on the saturation vapor pressure at 25 °C, and the relative humidity can be derived from these values.
If air at 25 °C has a vapor density of 9.40 g/m³ and the saturation vapor density is 23.0 g/m³ at the same temperature, the relative humidity can be found by dividing the actual vapor density by the saturation vapor density and multiplying by 100 to obtain a percentage.