>Mechanical Matters®

Welcome to Mechanical Matters®, an 'E-ZINE' publication brought to you from Jimmy Veteto, Solutions Provider, S.M. Lawrence Company, Inc.  Please take a time to read this great article as it pertains to your building's most important investment, your mechanical systems.  We are building mechanical solutions that matter every time by design.  

"Leave the Mechanical Matters® to us."

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 Free Cooling with the help of a Plate and Frame Heat Exchanger.

The FedExForum, home of the Memphis Grizzlies and the Memphis Tigers is the entertainment capital of Memphis, located just 10 feet off of Beale.  Actually more like 50 feet from the famous Beale street, but 10 sounds better. Whether you are cheering for the Grizzlies, singing along with the Rolling Stones, or watching the big boxing match, do you ever wonder how a facility this large is heated and cooled? Just over 3,200 tons of chilled water pass through miles of pipe, valves, coils, tubes and cooling tower media in order for your seat to be comfortable, and that comes at a premium courtesy of MLG&W. Below is a snap shot of the chiller room at the forum:

n 2005, S.M. Lawrence and the engineering department at the Forum discovered an oversight in the mechanical design of this prestigious facility.  During winter months when most buildings are in need of heat, the Forum will sometimes need cooling.  Including all the lights, cameras, sound equipment, kitchens, concession stands, restaurants, eateries and human bodies, the heat load can require the chillers to operate even in the fall and some winter months. 

The heat load during winter months was anticipated when designing the Forum.   The four (4) large air handlers that serve the bowl and the main corridors around the bowl were designed to include economizers to bring outside air into the arena.  The pictures below indicate what we call the 'bowl' and a look at one of the four air handlers that serve the bowl:

Economizer mode means that when ambient temperatures (outside) are colder than inside the arena, the chillers cycle off and outside air is brought into the facility by way of an economizer.  The economizer system is made up of vents and modulating dampers that allow the outside air into the building thus cooling.  This method of cooling the arena by utilizing an economizer, is what we call 'free cooling'.  The reason it's free is because we can eliminate the use of the chillers, which are huge energy hogs. 

"Free Cooling" is the production of chilled water without operating the chillers.  Free cooling is not really free as the chilled and tower water pumps and the tower fan(s) must operate. However, the pumps and fans operate with very little energy consumption as compared to the centrifugal chiller"

As engineered, the economizer systems for the bowl units operate flawlessly.  However, we discovered that during some cooler months, there is still a demand for chill water. Puzzled by this, we researched the controls systems and monitored the air handlers during a basketball game.  What we found is that while the main bowl units were operating in economizer mode, the hundreds of smaller fan coil units (small air handlers) that serve areas like concession stands, restaurants and eateries need chilled water to maintain comfortable room temperatures.  These fan coil units do not have access to outside air and do not come equipped with an economizer like the larger bowl units do.  Although though we are saving energy by operating the larger units in economizer mode, we still need to operate a chiller even in the winter months.  That's when we uncovered our solution.

If we were to install a Plate and Frame Heat Exchanger into the chilled water loop, then maybe we could add additional 'free cooling' to systems.  We designed a Heat Exchanger and a circulating pump as shown below:

For more about 'Modular Boiler Systems' please read the article below by

Since our installation of the Plate and Frame, we can cool the entire Forum during winter months with very little help of the chillers.  This 'free cooling' application by use of a Plate and Frame can best be explained by the following article by:

White, T.L., P.E. " A winter cooling tower operation for a central chilled-water system." ASHRAE Transactions: 1994, Vol.100, Part 1, Paper number NO-94-7-2, 811-816, 10 figs, 1994.

Free Cooling - Plate and Frame Heat Exchanger

During cool weather, the outside ambient temperature can help save energy in chilled-water systems. The low temperature of the cooling tower water supply enables free cooling of research laboratories, computer rooms, and office buildings. This free cooling is possible if the central plant incorporates a plate-and-frame heat exchanger to provide chilled water production, which means the chiller's compressor can be shut down. Free cooling can be used to save energy whenever the outside wet-bulb temperature drops below the required chilled water set-point. This energy-efficiency measure can save enough compressor electric power to pay for plate-and-frame heat exchanger installation costs in less than two years.

The project at the Forum was an $70,000.00 investment.  The payback is 2 years.  As the Forum hosts many years of Grizzlies games and entertainment events alike, this addition of a 'plate and frame heat exchanger' to one of the most sophisticated facilities in Memphis, will lower energy consumption and will save the Memphis Grizzlies thousands of dollars every year. 

To find out more if a plate and frame heat exchanger is right for your building, or if you are interested in other 'free cooling' applications, please feel free to call anytime.  We at S.M. Lawrence look forward to hearing from you.

-Jimmy Veteto, 901.378.7655

jimmyv@smlawrence.com