How to Determine the Temperature and Water Mass Flow in an Evaporative Cooler

What are the key parameters needed to calculate the temperature of the air leaving an evaporative cooler and the mass flow of water added in the cooler?

Calculating the Temperature of Air Leaving the Cooler

To determine the temperature of the air leaving the evaporative cooler, we need to consider the initial and final conditions of the air inside the cooler. The key parameters needed for this calculation are the initial specific humidity (omega1), the relative humidity of the air entering the cooler (RH1), the initial temperature of the air (T1), the final relative humidity of the air leaving the cooler (RH2), and the enthalpies at the initial and final conditions. Step 1: Calculate the initial specific humidity (omega1) using the given initial relative humidity (RH1) of 10% and temperature (T1) of 90°F. Step 2: Determine the final specific humidity (omega2) using the final relative humidity (RH2) of 80%, assuming constant enthalpy during the adiabatic saturation process. Step 3: Find the enthalpies of the air at the initial and final conditions using a psychrometric chart. Step 4: Equate the enthalpies at the initial and final conditions to calculate the final temperature (T2) of the air leaving the cooler.

Calculating the Mass Flow of Water Added in the Cooler

The mass flow of water added in the cooler can be determined by analyzing the change in specific humidity and the amount of water vapor absorbed by the air during the adiabatic saturation process. This calculation involves understanding the mass balance of water in the system and the change in specific humidity of the air. Step 1: Calculate the change in specific humidity (delta omega) by subtracting the initial specific humidity (omega1) from the final specific humidity (omega2). Step 2: Determine the mass flow rate of water added in the cooler by multiplying the change in specific humidity (delta omega) by the mass flow rate of dry air (1000 CFM). By following these steps and calculations, we can determine both the temperature of the air leaving the evaporative cooler and the mass flow of water added in the cooler accurately.

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