Evaporative Cooling

Applied Systems has fantastic series of options for providing evaporative cooling solutions for your building. In some applications in Western Oregon and Washington, we can provide 62°F air with NO mechanical cooling. On the east side of the states, we can run down near 55°F without refrigeration. Let us show you the power of water, and how it can save you money.

 

Evaporative Cooling - Direct

Using an extended surface media, such as Munters GlasDek, water is distributed across the media surface, where evaporation takes place, lowering the sensible air temperature, while maintaining a constant enthalpy until the air stream begins to approach saturation, near 95% RH. The leaving air is cooler, and much wetter. These systems have been referred to as swamp coolers, but the correct terminology would be direct evaporative cooling.

Evaporative Cooling - Indirect

One part direct evap cooling, one part indirect evap cooling. Using a heat exchanger, direct evap cooling occurs, thereby decreasing the air temperature of the exhaust air. The lower air temperature exchanges it's larger heat differential with the supply air stream, without adding any moisture to the supply air stream, hence the supply air is "indirectly" cooled, with a shift in enthalpy occurring during the process.

Using a corrosion-resistant polymer heat-exchanger to produce dry, cool air without using refrigeration. The polymer tube construction prevents corrosion, and the unit's design eliminates water leakage. The heat-exchanger core incorporates unique, vertical polymer tubes. Water flows inside and down the tubes, counter-flow to a scavenger ambient-airstream or return airstream. The air to be supplied to the space flows across the outside of the tubes and is sensibly cooled - no moisture is added. A special surface-wetting interior-finish promotes enhanced evaporation for maximum efficiency. Polymer Indirect heat exchangers can provide total cooling capacity. It can cool the incoming air to 30 degrees Fahrenheit or less, in winter time, these act as 55% efficient heat recovery devices as well.

Combination IDEC - DEC systems -

A more recent development has been to marry these technologies in a single air system. While there are many potential configurations, I'll only discuss the simple process for a 100% OA unit. Using the indirect evap cooling module on the incoming outside air, has an initial reduction of OA temperature of 20 some degrees, then the air passes through a direct evap cooling module, which cools the air to near saturation. On a design summer day, delivering air at 55° if quite feasible since our summer dewpoint temperatures are so low. Obviously, this won't be applicable to climates with higher mean wet bulb temperatures. On the design humidity day, 62°F, we can supply air BELOW the OA dewpoint, because we're using return air on the IDEC section of the unit, shifting the enthalpy, and then re-humidifying the air. Delivered air temperature of 62° degrees on the western half of the state is feasible, without refrigeration. As you move east, the psychrometrics improve so much that 55-57° delivered air temperatures are achievable.

Maintenance misconceptions -

The DEC and IDEC units are quite simple devices, with a sump, a distribution pump and some PVC piping for water distribution. I would go as far to say, mechanically they are simpler than your standard rooftop package unit. Sump water is purged once a day, so there is no need for chemical treatment. The media is simple, the controls are all standard devices. Depending on water quality, you may need to perform some cleaning or DEC media replacement over the long term. We have proven installations in Badwater California, where the IDEC media has been in operation for 8 years, performing under intense heat conditions with the WORST water quality in the country.

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