Filtration Facts

Evaporative Condensers Reduce Costs of Refrigeration

  

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It takes a LOT of energy to keep a popsicle frozen in the desert.  Come to think of it, it takes a lot of energy to keep a popsicle frozen in any conditioned interior space – in a desert or anywhere else.  

Grocery store owners know this all too well.  According to National Grid, refrigeration accounts for 44 to 62% of the energy consumed in U.S. grocery stores depending on the climate zone.  So when grocery store owners are looking to economize on energy, refrigeration is a smart place to start.  In fact, refrigeration system optimization can reduce energy use by 24% relative to standard practice.  This could account for a substantial increase in a grocery store’s profits, since energy expenditures are approximately equal to a typical grocery store’s profit margin.

Evaporative Condensers vs Cooling Towers
Evaporative condensers are an effective way to trim refrigeration energy cost in grocery stores, as well as in many other businesses.    These devices operate similarly to cooling towers in that they remove heat from the refrigeration system.  However, in cooling towers, the cooling water does not come into direct contact with the equipment being cooled; instead it passes through a refrigerant-water heat exchanger in the condenser to achieve thermal transfer.  Evaporative condensers, however, spray water directly over the coils and a fan blows air through the falling spray of water.  As the water evaporates, the remaining water becomes cooler through what is known as the latent heat of evaporation.  The cool water absorbs heat from the condenser coil, cooling the refrigerant into liquid form.  This is an energy efficient means of heat removal and can result in significant savings.  

Although evaporative condensers can be significant energy savers for businesses with high refrigeration needs -- particularly in more arid climates -- they come with one disadvantage.  They use a lot of water, and this water must be periodically “bled” off into the sewer to prevent the accumulation of excessive mineral deposits, such as magnesium, silica and calcium.  These minerals build up on the condenser coils, impairing heat transfer and thus efficiency.  In addition, the air flowing through the water spray contains many particles such as pollen, mold and dust that eventually accumulate inside the system.  Frequent bleed rates (along with chemical treatment) are used to combat these particulates.  The outside contractors that service cooling towers and evaporative condensers have been known to use tower bleeds liberally to prevent scale formation.  After all, they don’t pay the water bill.  Their top priority is to prevent scale formation—period.    

Water Waste

How much water is used as a result of evaporative condenser operation?  According to the Alliance for Water Efficiency, many systems used 50% more water than necessary.  

Filtration Can Reduce The Waste And Improve Efficiency
Cooling tower basin cleaning is one way to minimize the bleed rate/water waste on cooling towers and evaporative condensers. Effective filtration of evaporative heat rejection systems, which includes centrifugal separation, also helps prevent the accumulation of bacteria that leads to Legionnaire’s Disease. 

You can read more about this by downloading “Fighting Legionella with LAKOS”.