Understanding Air Processing in a Spray Washing System

A spray washing system, also known as an air washer, is a device used to process air. It involves passing air through a chamber where water is sprayed. The interaction between the air and the water spray leads to changes in the air's temperature and humidity.

How Air Changes When Water Temperature is Higher Than Air Dry Bulb Temperature

In a spray washing system, when the temperature of the spray water is higher than the dry bulb temperature of the entering air, both heat and moisture transfer occur between the water and the air. Let's break down what happens:

• Heat Transfer: Since the water temperature is higher than the air temperature, heat will naturally transfer from the warmer water to the cooler air. This causes the dry bulb temperature of the air to increase, meaning the air gets heated.
• Moisture Transfer (Humidification): Water is being sprayed into the air stream. When the air passes through this water spray, it picks up water vapor, increasing its moisture content. This process is called humidification. While evaporation cools the water (adiabatic humidification), in this scenario, the water is kept at a higher temperature. The warmer water has a higher vapor pressure than the cooler air, facilitating the transfer of water molecules from the liquid phase in the spray to the vapor phase in the air. This adds moisture to the air.

Therefore, when the water temperature in a spray washing system is higher than the dry bulb temperature of the entering air, the air is both heated by the warmer water and humidified as it picks up moisture from the spray.

Result of Higher Water Temperature

Combining the effects of heat transfer and moisture transfer:

• The air gains heat from the warmer water.
• The air gains moisture from the water spray.

This leads to the air becoming heated and humidified.