Evaporative Cooling Scientific Facts

You may have wondered why you haven’t heard about evaporative cooling before, or whether or not evaporative cooling is a gimmick. Simply put, evaporative cooling is not new technology and is well grounded in scientific fact. A scientific explanation of evaporative cooling and why Breezair coolers are better follows.

To understand evaporative air-cooling, it is important to know the relationship between dry air and water vapor, as well as some technical terms.

    1. Dry bulb temperature (db) is the degree (not amount) of heat measured with a regular thermometer.
    2. Wet bulb temperature (wb) is the degree of heat measured with a “wet sock” attached to the bulb. The Wb is also the temperature at which water evaporates when air is blown over the wet surface.
    3. Relative humidity (rh) is the ratio of the amount of water (as vapor) actually contained in the air to the maximum amount of water vapor that could be contained at the same temperature (saturation). For example, at 50% rh, the air contains 50% of the maximum (100%) amount of moisture (water vapour) that it could contain at the same temperature.
    4. Adiabatic cooling is the direct evaporative cooling process, whereby the dry bulb temperature is lowered without altering the amount of heat in the air.
    5. Latent Heat is the heat absorbed by the moisture as it changes from liquid to vapor during evaporation. This heat is absorbed by the vapor without any increase in its temperature – an important physical phenomenon.
    6. Media or Filter Pad or Evaporation Pad is the screen through which air must pass to come in contact with the water.

Basic considerations of airflow are volume and velocity. Volume is the amount of air (expressed in cubic feet per minute (CFM)), and velocity is the speed of air (expressed in feet per second (FPS)). The volume of air through the media affects the cooling capacity of the Air Cooler along with the evaporation rate of the water. The volume of air also affects the ability of the Air Cooler to reduce the temperature of a room.

The velocity of the air through the media is an important criterion for determining efficiency. Velocity is also important in preventing water carry-over and blow-off.

Warm air can hold more moisture than cold air, and therefore when air is heated without changing the moisture content, the relative humidity drops. Conversely, when air is cooled, the relative humidity rises.

In an Evaporative Air Cooler the latent heat that is absorbed by the water as it changes from liquid to vapor is taken from both the air passing through the media and the water left in the media – so both the air and water are cooled and their temperature falls. The water does not concern us, but the cooled air is what we want.

Evaporative Cooling Scientific Facts Image 1

The above illustrates that when water passes over the media and air is blown through it, water evaporates and the air is cooled so that the dry bulb temperature of the cooled air approaches the original air wet bulb temperature.

Note that the total amount of heat has not changed, but its nature has changed. The small amount of latent heat in the original water vapor in the air has become larger because of an increase in the amount of water vapor, due to evaporation.

Product Features

Chillcel Cellulose Pad
At Breezair we manufacture our own high-density, cross-corrugated ChillCel cellulose pads. They’re matched to your cooler for maximum effect. Our ChillCel pads provide the highest cooling efficiency of any evaporative medium. On average, ChillCel pads are around 4″ thick, which we believe provides optimum efficiency. Other brands may claim that thicker pads provide better cooling. The facts are that only a certain amount of water can evaporate into the air. Thicker pads cannot make any more water evaporate – unless the pads themselves are quite inefficient to begin with. Thicker pads may require greater power to draw the air through, a larger pump to move the volume of water required and provide an ideal environmnet for efficiency sapping salt and mineral buildup. In other words, they probably cost more to buy, more to run and need to be replaced more often.

Ribbon Cut Aspen Pad
Aspen fiber or Wood Wool pads are a natural product that have been used in evaporative coolers for many years – and many people swear by them. If kept in good condition, particularly by removing and flushing at least once a year, they provide very good cooling efficiency. They generally last approximately half as long as cellulose pads.
An advantage of fiber pads over cellulose is that they’re usually less expensive. Therefore, where there’s very poor water quality or extremely dirty conditions, meaning that pads may need to be replaced more often, they’re an economical choice.
Breezair Aspen fiber pads utilize high quality wood fiber cut to optimum strand length and thickness. The pads are packed in the best density to match your cooler.

Uniform Water Distribution
Why have an excellent pumping system and the most efficient pads available if you can’t deliver water to them evenly and efficiently?
We invented the non-clog water distribution system which is found in every Breezair cooler. Our water distribution system prevents blockage and keeps the pads evenly saturated for higher performance. No dreaded dry spots – not only do dry spots not cool, they let the hot, dry outside air right into the air stream! The ideal volume of water is pumped from the sump to the water distribution system where it cascades evenly across the pads, from side-to-side and front-to-back. And you’ll never hear the sound of trickling water either.

Quiet, Lightweight Fan

Our exclusive one-piece aerodynamic fan design delivers the largest volume of cool air with the least wear and tear on the motor. That means better cooling, quieter operation, longer motor life and lower operating costs. Most other cooler brands do not have a blower fan. Why? Because they’re very difficult and expensive to manufacture. At Breezair, we cut no engineering or manufacturing corners to deliver you the best possible cooler design, including the fan. Another advantage of a centrifugal blower fan is that it generates higher pressure than conventional axial fans. That means a Breezair can quietly and effortlessly force air through even the most demanding ductwork designs – it helps get cool air where it’s needed most.