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Portable Cooling is an Engineered Solution

Friday, July 08, 2016

When a facility loses its air conditioning, major problems can ensue. Not only will building occupants become uncomfortable, but critical processes may be compromised if the existing cooling equipment can’t be fixed promptly. If repairs cannot be done quickly, then portable cooling may be the solution.

Within hours of discovering the cooling equipment doesn’t work, building management can contact a portable cooling company and have them deliver and stage the necessary equipment. The reason why most portable cooling companies can respond so quickly is that they do a lot of work behind the scenes to make sure they’re prepared for just about any situation.

Contrary to popular belief, there is much more involved than simply rolling in portable cooling equipment and turning it on. Portable cooling is not a commodity – it is an engineered system that requires a tremendous amount of coordination and engineering know-how. The applications discussed in this article highlight the hands-on approach of portable cooling equipment companies and demonstrate how they’ve had to think outside the box in order to keep their customers cool.

Flower Power

When Mother’s Day arrives, the chances are that the bouquet you’re going to buy for Mom will come through Miami International Airport. MIA leads all U.S. airports with 85% of the 165,000 tons of fresh-cut flowers imported into the United States every year. By comparison, the next two largest ports of entry for imported flowers are New York City, with 7%, and Los Angeles, with 3%.

Mother’s Day is the second most important day of the year, after Valentine’s Day, for the United States’ $19 billion floral industry. In the weeks preceding those occasions, workers at MIA brace for a floral deluge. On any given day, MIA handles 32,500 boxes of flowers. But in the weeks leading up to the two peak holidays, that figure doubles or even triples, skyrocketing to some 35 planeloads of flowers a day.

After those flowers pass through MIA, they are taken by truck to refrigerated warehouses surrounding the airport, where they are sorted and shipped out all over the country. In January of this year, a brand new 13,000-sq-ft warehouse wasn’t prepared for the influx of flowers arriving for Valentine’s Day. The facility was built and ready to house the flowers, but its cooling system was not quite ready.

The owners were panicked, wondering what could be done to keep the hundreds of thousands of dollars’ worth of flowers from wilting in the Miami heat. They looked around on the Internet and discovered Carrier Rental Systems (www.hvacportablesystems.com) in Lakeland, Fla. “Our guys asked them more questions over the phone, gave them an initial concept, and then they went down to Miami to assess the project,” says George Doring, area general manager, Carrier Rental Systems.

They ended up designing a unique portable cooling system for the floral warehouse that utilizes propylene glycol and consists of a chiller, air handlers, pump, generator, fuel tank, cable, fittings, flexible hose, and duct. A glycol solution was necessary, because the warehouse needs to be kept at a constant 40°F, thus the circulated glycol needs to be about 22°F. An alternating defrost cycle allows one machine to run while the other defrosts.

The portable system was delivered two days after the site meeting, and it took one day to set up the equipment. The system did not achieve the desired temperature right away, due to the fact that trucks bearing flowers were driving in and out of the warehouse for the first two days. After the doors were closed, the warehouse reached its optimum 40°F temperature.

“This was a very unique application,” says Doring. “Our company presented a comprehensive solution that addressed all the owners’ concerns, as well as potential problems they did not initially consider. Our people ask the right questions to understand each application. They start by asking the customer, ‘what are you trying to accomplish?’ so we can provide the best engineered system possible.”

Remote Units Cool Computer Room

A major bank has large mainframe computers located in a very nice downtown office building in the southeastern United States. The computer is used for the bank’s extensive trading operations, so when the building needed to shut down its chiller plant for repairs, the bank knew it would need portable cooling.

The chiller plant will be repaired over a six-week period, during which time eight 12-ton portable cooling units from Spot Coolers (www.spot-coolers.com) will be used for two computer rooms located on separate floors of the building. There is no room for the portable equipment in either computer room, and neither space could handle the amount of heat being rejected by the portable units.

Fortunately, Spot Coolers has units that are made precisely for this type of application, says Garth Tagge, vice president, Spot Coolers. “The computer rooms are in the center of the building, and there is hallway all the way around each room. We’re putting the units outside the rooms, and we’re ducting the cold air in and pulling the return air out.”

The condenser air will be ducted to several places, including into a stairwell, a mechanical room, and out a window. Condensate will be pumped to a bucket in the stairwell, a sink in the mechanical room, and out the window.

Building management was originally looking at performing all the repairs on the chiller plant at once, but they decided to do it in steps over six weeks to reduce the risk of catastrophic failure. Since the work will take place on week-ends only over a six-week period, the portable cooling units will also have to be taken down and set up six different times.

Tagge notes that his company is often called upon to provide portable cooling for computer rooms and other places that can experience immediate hot spots. “The challenge with this job,” he says, “is that the cooling capacity is not going to be spread out – it is all localized in one area.”

Heat rejection becomes critical in a confined space, because proper cooling can’t take place if the heat being exhausted from the portable units is then pulled back into the units. The goal is to get the rejected heat away from the units (e.g., into a stairwell, out a window) so that the air coming back to the units is cool.

Computer rooms usually have a limited number of entries and exits, so it can be a challenge to figure out where the air needs to be ducted. As shown in this application, with proper planning and an understanding of the space’s specific needs, those issues can be figured out ahead of time.

Show Must Go On

The Morton H. Meyerson Symphony Center in Dallas opened in September, 1989 and is home to the Dallas Symphony Orchestra and other Dallas-based cultural organizations like the Turtle Creek Chorale, the Dallas Wind Symphony, and the Greater Dallas Youth Orchestra. “The Meyerson” has 260,000 square feet above ground, 225,000 square feet below ground, 4,535 organ pipes, 2,062 seats, and 74 concrete reverberation chamber doors, each weighing as much as 2.5 tons.

The Meyerson also has a cooling tower that is in the process of being replaced. The cooling tower wasn’t really that old, but its lifespan was shortened due to the way it was originally installed. Aesthetics were very important to the architect, so the cooling tower was placed inside the building – out of sight -- and was only accessible through a hole in the roof. Unfortunately, this arrangement restricted air flow across the tower, resulting in air and moisture circulating back through the tower, which reduced capacity and promoted corrosion.

The existing cooling tower is being removed in pieces, and the new cooling tower will have to be installed in pieces. It is estimated the project will take approximately three months to complete, during which time The Meyerson will be kept comfortable through the use of portable equipment supplied by Texas-based Entech Sales and Service (www.entechsales.com).

“We had some experience with this building and actually provided a 400-ton rental chiller several years ago,” says Pat Rucker, president, Entech Sales and Service. Entech designed a portable system for The Meyerson consisting of two 400-ton air-cooled chillers, each mounted with a pump on a 55-ft trailer. These were installed back-to-back along an access road on one side of the building. The chilled water piping was snaked through the building to the point where it could be connected to the existing chilled water piping.

“Our experience with the building allowed us to point out several potential problems to the contractor and engineer,” notes Rucker. One of those problems involved using flexible hose inside the building. Entech pointed out that flex hose is not reliable and that The Meyerson would run the risk of flooding the building.

“We proposed running steel pipe as part of our basic bid,” says Rucker. “Keeping the piping out of the way was a necessity, so we had to fabricate support brackets for the piping, which ran up and over a marble wall. We ended up having to re-route some piping due to the fact that it was blocking some access to the power company’s main power transformer vaults.”

Some of the valves were also controlled from the building automation system, so the BAS had to be disabled and the valves were blocked open in order to ensure that chilled water would circulate uninterrupted to the chillers. Other than that, the two-week installation went smoothly, and patrons who attend concerts and recitals should never know that portable chillers are keeping them comfortable.

Computer Crisis Averted

David Martin, service manager, Suburban Service Corp., Norwood, Mass., frequently relies on portable cooling equipment to keep his customers comfortable. Some customers require portable cooling for a short period of time, so renting the units makes sense. Other applications require a permanent solution, so buying the equipment is the right solution.

This was the case at a software company in Andover, Mass., which was renting space in a Class 1A office building. The existing cooling system in the building wasn’t sufficient for their computer room, which had been loaded up with servers over the years. A 3-ton cooling unit had been permanently installed in the room, but even with that, temperatures were approaching 90°F. Martin was brought in to assess the situation.

“We really tried to give them a more permanent solution than portable air conditioners,” says Martin, “But the property management company didn’t want a condensing unit outside the building on the ground, which means we would’ve had to put it on the roof. However, the software company is located on the first floor, so we would’ve had to have gone through tenants on the upper floors, and the cost would’ve been astronomical.”

Martin suggested the company consider buying portable cooling units to address their needs. The company was initially skeptical, but Martin pointed out that the units would cost less than a more permanent solution, the units would be available quickly, and if the company ever decided to leave the building, they could take the units with them to the next building.

The company decided these reasons made sense, so Martin contacted Scott Sherman at JB Fleming, Marlborough, Mass., a manufacturer’s representative for MovinCool (www.movincool.com). The two of them decided that the 20- by 8-ft room would require 7-1/2 tons of portable cooling, so a 5-ton unit and a 2-1/2-ton unit were installed.

Martin still had to get permission from the property management company, because the portable units would be adding quite a heat load to the building’s cooling system. Fortunately, building management was accommodating, because they knew their tenant had to have additional cooling. The units were installed and the rejected heat is being ducted up into the ceiling plenum. Condensate is being pumped to a janitor’s sink.

There wasn’t a lot of extra floor space in the room to begin with, so the portable units had to be installed in the far corners of the room. The conditioned air needed to get to the equipment, so cold air extension ducts were installed to spot cool the servers. “They needed to duct that cool air remotely from the unit,” says Sherman. “So we provided them with an attachment that fits over the grille that has two ports to which two 8-in. diameter flexible ducts are attached.”

The units have been up and running for a year now, and the temperature in the computer room is now between 65° and 72°F. “We do maintenance for the building’s HVAC systems, so while we’re there we check on the MovinCool units. Things have been running smoothly, with no problems at all,” reports Martin.

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