• Contractingbusiness 1817 43192rssd0100jp00000019485

    Evaporative fogging brews up energy savings

    Nov. 1, 2006
    By Marc Sandofsky table width="200" border="0" align="right" cellpadding="5" cellspacing="0"div align="center"img src="/images/archive/43192rssd0100jp_00000019485.jpg"

    By Marc Sandofsky

    High pressure fogging nozzle.

    The ConsERV system recaptures roughly 65% of the energy that would otherwise be expelled outdoors.

    Cooling kW installed a liquid desiccant dehumidification system sized to provide 5-tons of latent cooling, and 3-tons of sensible cooling.

    Berkshire Brewing Company, Inc. (BBC), South Deerfield, MA, has seen its business grow in 12 years, from 24 barrels per week, to upwards of 420.

    Energy use has also increased proportionately. Therefore, when Western Massachusetts Electric Company (WMECO) suggested that BBC invest in energy conservation, BBC founders Christopher Lalli and Gary Bogoff took interest.

    "As a small, self-financed company, we've always been conscious of our overhead, especially our energy usage, and we view energy conservation as the environmentally responsible thing to do," Bogoff says.

    BBC had instituted a number of energy conservation measures over the years, and was in the process of upgrading its refrigeration systems when approached by WMECO.

    "Since most of our refrigeration equipment was new, we were skeptical at first that WMECO could lower our energy usage much, and certainly not without our having to make a large capital investment, however, both of those concerns turned out to be unfounded," Bogoff says.

    Because of the fact that refrigeration accounted for the majority of BBC's energy use, WMECO Small Business Energy Conservation Manager Kim Kiernan introduced Bogoff to Cooling kW, Windsor Locks, CT, specialists in cooling-related energy conservation.

    "WMECO works with outside engineering firms and vendors to design and implement energy conservation strategies," Kiernan explains. "We recommended Cooling kW because their primary focus is on refrigeration, air conditioning, and indoor air quality."

    System Filters Water, Cools Air, Reduces Load
    BBC's refrigeration systems are packaged, air-cooled, and located in a mechanical room in the back of the facility. Heat is rejected directly into the mechanical room to air drawn in through louvers. The heated air is then exhausted through a roof-mounted fan.

    As with all air-cooled systems, as the outside (ambient) temperature rises, less heat can be rejected, since hot air can't absorb as much heat as cold air. Operating (head) pressures rise, and the systems draw more power. Therefore, on hot days, cooling capacity falls, and energy use increases.

    Table 1 shows the power draw and cooling capacity at various ambient temperatures of a 100-ton chiller. A 30F rise in ambient temperature causes the power draw to rise from 118.3 kW to 156.2, and the cooling capacity to fall from 104.6 tons to 83.6. This represents a 65% decrease in chiller efficiency. This same relationship held true at BBC. As the temperature of the air entering the mechanical room through the louvers increased, energy use rose and cooling capacity fell.

    TABLE 1

    Ambient Temp (F) Power Draw (kW) Capacity (Tons) kW/Ton Cooling Efficiency Decrease
    85 118.3 104.6 1.13
    95 129.5 98.0 1.32 16.8%
    105 142.2 91.1 1.56 38.0%
    115 156.2 83.6 1.87 65.2%

    As a solution, Cooling kW installed a C3 evaporative fogging system manufactured by MicroCool, Thousand Palms, CA.

    A high pressure pump used in combination with a reverse osmosis filtration system removes unwanted minerals from the water, and creates a cool fog, which is directed through high pressure fogging nozzles. As the fog is absorbed into the air, the temperature is lowered, energy use is reduced, and cooling capacity is increased.

    "With the MicroCool C3 system, at 95% outside air temperature, we're seeing a temperature drop of more than 20 degrees," Bogoff reports. In addition to about a 15% drop in power draw (kW), our compressors are cycling off, which has never happened before."

    Beyond the energy savings and increased cooling capacity, BBC expects lower maintenance costs, and increased system life.

    "Elevated head pressures are extremely detrimental to compressors," says Cooling kW co-founder Rick Tomasko.

    "By lowering the head pressures with the C3 system, the compressor life should be extended."

    Liquid Desiccant Dehumidification System
    Studies have shown that refrigeration system energy use can be adversely effected by elevated indoor humidity (RH) levels. Since BBC is constantly using water for beer manufacturing and equipment wash downs, indoor RH levels tend to be very high.

    To solve this problem, Cooling kW installed a liquid desiccant dehumidification system, sized to provide 5-tons of latent cooling, and 3-tons of sensible. The system passes indoor air over a filter-like media saturated with a concentrated desiccant solution.

    The humidity is dissipated outdoors by passing a separate outdoor air stream over a second media saturated with the diluted desiccant solution.

    ERV Recaptures 65% of Energy
    Increased beer production caused the carbon dioxide levels in the BBC fermentation room to reach a point where indoor air had to be constantly expelled and fresh air introduced. Since BBC would have been required to heat the fresh air in the winter and cool it during the summer, energy use would increase.

    To minimize increased energy use associated with the introduction of the outside air, Cooling kW installed a ConsERV energy recovery ventilator (ERV) manufactured by Dais Analytic, Odessa, FL.

    Comprised of a supply air fan, exhaust fan, and air-to-air heat exchanger, the ConsERV system recaptures roughly 65% of the energy that would otherwise be expelled outdoors in the exhaust air, transferring the energy to the makeup air, and minimizing the need to treat the outdoor air.

    According to ConsERV's calculations, the energy use associated with the introduction of this makeup air is reduced by upwards of 65%.

    Other Steps Reduce Energy Use
    Cooling kW initiated other energy saving measures:

    • Plastic strip curtains were placed at the entrance to each walk-in cooler. Previously, the cooler doors were left open much of the day.
    • Chilled water piping was covered with insulation, to prevent heat from reaching the chilled water. In the past, the heat would raise the water temperature and cause the refrigeration system to run longer to remove the added heat.
    • Cooling kW reduced BBC's lighting energy usage by 22, 217 kWh per year by replacing two-lamp fixtures with one-lamp fixtures, and adding reflective optics.

    Adding Up the Benefits
    Through this variety of energy conservation measures, BBC expects to realize the following benefits:

    • A reduction in annual energy usage of 170,970 kWh.
    • A reduction in peak demand of 79 kW.
    • A reduction in annual energy costs of $25,647.
    • An increase in peak cooling capacity of about 15%.
    • A decrease in indoor RH of up to 30%.
    • Increased system reliability.
    • Increased system longevity.
    • Reduced maintenance costs.

    The entire project was installed with no out-of-pocket costs to BBC, due to WMECO's rebate program, which contributed $64,508 to the total project cost of $128,140, and financed the remainder at 0% interest over 24-months

    "We're obligated to repay the loan portion, but we expect that to come out of the energy savings we realize over the next two years," Bogoff says.

    "After that, all the savings will go toward reducing our overhead costs."

    Marc Sandofsky is a former editor of Refrigeration Systems & Store Design Magazine and presently works as a consulting engineer. He may be reached at [email protected]