A building is to be cooled in the summer season in a hot and dry region where the outdoor design conditions are 110 oF DB and 65 oF WB. The building sensible and latent heat gains are 300,000 Btu/h and 50,000 Btu/h, respectively. Air conditioning is to be performed using a spray water evaporative cooler employing recirculated spray water (with no heating or cooling) with a humidifying effectiveness of 85%. The evaporative cooler employs 100% outdoor air at the rate of 12,000 cfm measured at the outdoor conditions. The air exiting the evaporative cooler is directly supplied to the building. Compute the following: (a) the supply air dry- and wet-bulb temperatures, relative humidity, and enthalpy; (b) the mass flow rate of the air passing through the evaporative cooler in lb/h; (c) the volume flow rate of air entering the building in cfm; (d) the dry- and wet-bulb temperatures and the relative humidity of the air in the building; and (e) the amount of moisture injected into the building in lbv/h.

Case B: If another evaporative cooler (whose humidifying effectiveness is unknown) is used with 25% recirculated air and 75% outdoor air, while maintaining the same outdoor and building conditions as well as the building sensible and latent heat gains the same as in Case A, compute the following: (f) the dry- and wet-bulb temperatures of air entering the evaporative cooler; (g) the dry- and wet-bulb temperatures of air leaving the evaporative cooler and entering the building; (h) the humidifying effectiveness of the evaporative cooler; and (i) the amount of moisture injected into the building in lb v/h. Represent all state points and processes on the psychrometric chart and submit it with your answer sheet

Answer rating: 100% (QA)

To solve this problem well use psychrometric charts and formulas to calculate the various parameters ... View the full answer