A lecture hall is 20m 15m 12m and contains an air water v

A lecture hall is 20m × 15m × 12m and contains an air / water vapor mixture (moist air) at standard atmospheric pressure. The temperature (dry bulb) is a comfortably cool 15°C. Use a psychrometric chart (available in the lecture notes and various places online) to help you determine the following quantities assuming: A. a dry 20% relative humidity, and B. an uncomfortable 100% relative humidity. The quantities are: 1. wet bulb temperature [°C] 2. humidity ratio 3. dew point temperature [°C] 4. mass of dry air in the room [kg] 5. mass of water vapor in the room [kg] 6. specific enthalpy of the moist air in the room [kJ/kg] 7. total enthalpy of the moist air in the room [kJ] 8. mass of water vapor condensed if the moist air is cooled at constant pressure to 5°C [kg] 9. thermal energy that must be extracted from the mixture to cool the moist air in the room from original conditions to 5°C [kJ] Need help with parts 8 and 9.

Solution

Steps & process to solve part 8 & 9

8)

using psychrometric chart

locate the point using given relative humdity & dry bulb temperature

corresponding to that point, find the specific humidity

difference in new specific humidity & previous value will give mass of water vapour condensed.

9)

similary for this part

locate the point using given relative humidity & temperature

corresponding to that point, find value of enthalpy &

difference in value of new enthalpy & previous value will give thermal engery need to be extracted.