Question

A lecture hall having a volume of 106 ft3 contains air at 80°F, 1 atm, and a humidity ratio of 0.01 lb of water vapor per lb of dry air. Using the appropriate equations, determine(a) the relative humidity.(b) the dew point temperature, in °F.

Answer 1

Answer:

(a) %RH = 45%

(b) Dp Temp = 58 °F (14.44 °C)

Explanation:

We can obtain the results easily and faster with a psychometric chart. (See the attachment). In the graph we can see how we obtain results crossing the respective data (marked in red).

First, for the relative humidity, we cross the humidity ratio (starting from the right side) with the dry temperature (horizontal axis). In that way we can read from the relative humidity curves the value of 45%.

After that, we extend the horizontal line from the right side until the left side and cross it with the 100% saturation curve in order to read the dew point temperature. Here we obtain the value 58 °F (14.44 °C)