Evaporative coolers cool the air by using a series of evaporative processes to convert hot dry air into cool air. The process involves drawing warm air through dampened pads. This draws out the natural heat of the air and injects cooler air into your workspace. Evaporative cooling is now an alternative to traditional cooling in commercial or industrial buildings. Manufacturers now offer two-stage, “indirect-direct” evaporative cooling systems. This increases the cooling effectiveness and expands the geographical range that which evaporative cool can be used.
Different Types Of Evaporative Cooling
There are the 2 types of evaporative cooling first is direct evaporated cooling and second is indirect evaporated cooling.
What Is Direct Evaporated Cooling?
Direct evaporative cooling cools the air by evaporating water, which increases its moisture content. Evaporative media consisting of shredded aspen fibers and typically 1 to 2 inches thick, is used in standard cooling systems. These systems are effective at 55 to 70%. (Effectiveness refers to how close the temperature of the air entering the portable evaporative cooler is to the outdoor wet-bulb temperature). The following factors define effectiveness:
TDB refers to the outdoor dry-bulb temperature, while TWB refers to the outdoor wet bulb temperature. SAT stands for supply air temperature.
System effectiveness is affected by the thickness of the media as well as the air velocity. Advanced evaporative cooling systems employ a rigid medium of 8 to 12 inches in thickness and can achieve an efficiency of between 80% and 90%. Direct evaporative cooling is suitable for hot and dry environments where the design wet-bulb temperature is at least 68 degrees F. Other climates have too high outdoor humidity levels to allow sufficient cooling.
What Is Indirect Evaporative Cooling?
Indirect evaporative cooling is a method that uses an air-to-air heat exchanger to remove heat without adding moisture. The hot, dry outside air is passed through a series of horizontal tubes that are humidified on the outside. The coils are surrounded by secondary air streams that blow over them and expel the moist, warm air. As it passes through the tubes, the outside air is cooled.
The number of air passes required to meet cooling demand increases with a higher pressure drop. However, the cooler’s high effectiveness allows for a wider geographic reach.
Evaporative Cooler Controls
Variable air volume control is a new feature that has been introduced to both commercial and industrial evaporative cooling units. A lower air velocity also increases heat transfer efficiency, reducing fan power.
Sensors to monitor system performance are a feature that is not often found on evaporative coolers. System effectiveness can be estimated by temperature and humidity measurements. The static pressure gauge measures pressure drops across media and can be used to estimate when maintenance is needed.
Because of the higher temperatures in the air than in traditional air conditioning systems, it is necessary to use more air to provide cooling. Because it is typically 100% outside air, evaporative units can match the mechanical exhaust loads of buildings.
Evaporative Cooling – Benefits
Evaporative cooling systems are both commercial and industrial. These cooling systems consume a fraction of energy compared to traditional compressor-based cooling systems. Evaporative cooling systems are highly efficient and can reduce energy consumption by up to 70%. However, the actual savings will depend on the type of evaporative cooler and the climate. The units can dramatically reduce peak demand in dry climates, where evaporative cooling can meet all loads. Evaporative cooling systems use only 100% of the outside air to cool, which can help improve indoor air quality and reduce operating costs.