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U.S. Army Soldier & Biological Chemical Command
U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Kansas Street
Natick, MA 01760-5012

Contact: Chief, Public Affairs Office
(508) 233-5340

Date: November 19, 2001
No: 01-61

Cold storage

Natick, Mass. --- To eat hot meals made from fresh or frozen ingredients on a deployment, the military needs cooks, kitchens, and just as important, refrigeration.

Four new refrigeration systems programs are in various stages of development at the U.S. Army Soldier Systems Center (Natick) and will help the U.S. military more efficiently store and distribute cook-prepared rations from perishable ingredients much earlier to troops in the field.

The requirements were a result of the lessons learned following Operation Desert Shield and Desert Storm when troops ate packaged rations three times a day for several weeks at a time.

"It's a significant morale booster to get fresh rations in the field," said Paul Mandile, project officer for DoD refrigeration systems. "You can't deliver them without a reliable way to keep the food from spoiling."

Storage of fruits, vegetables, meats and other foods that need cold storage is the main job of refrigeration systems, but they can also preserve medical supplies, such as blood, and if necessary can be used for mortuary affairs.

Refrigeration systems are moving away from military-specific to commercial off-the-shelf models, which couples the latest energy-efficient, non-ozone depleting cooling technologies and global service network for speedy repairs and easy access to spare parts. Commercial brands also offer multi-year warranties for risk-free operation early in their service life.

However, Mandile said insulated containers are still built to military-specifications because the Army, Air Force and Marine Corps have unique service requirements unmet by the commercial market. These new refrigeration systems will increase thermal efficiency and restore the quality lost in current containers that have deteriorated during years of use.

USMC 8x8x10 ISO
Mechanical refrigeration units produced by Thermo-King have already been retrofitted to the Marine Corps 8-by-8-by-10-foot ISO refrigerated container used to store temperature-sensitive cargoes. The next task is replacing the insulated containers.

The new electric-driven refrigerators produce 25 percent more BTUs with a 66 percent decrease in power consumption. They are 20 percent lighter and 15 percent more thermally efficient than the units they replaced.

"Many of the current refrigerated containers are more than 20 years old, inefficient, and have reached the end of their useful service life." Mandile said. "One huge bonus is that the Marines received a three-year extended warranty at no additional cost and paid half the initial procurement cost for the new refrigerator."

While removing the old refrigerators from the container, deterioration of the container was easy to see. Wooden frames holding the units in place had dry rot, while rust was widespread in the container's steel frame.

The current container has an aluminum skin on both sides of a steel frame. Mandile said the insulation efficiency had degraded and its performance had decreased.

The new container will still meet ISO standards, but designers are investigating fiberglass composites and aluminums that won't corrode.

Advanced materials are expected to provide adequate strength, increase usable volume, cut weight and boost thermal efficiency.

The refrigerator and container are able to cool in transit if there's power available, similar to the commercial trucking industry. Because of its increased thermal performance, the new container will also hold its cargo at a safe temperature for a longer period without power.

"If the refrigerator or generator fails, the product will stay at its temperature for at least 24 hours at an outside temperature of 120 degrees F," Mandile said. A prototype container is scheduled for delivery by summer 2002 with production scheduled to begin early in 2004.

Instead of placing three 150-cubic-foot containers on a C-130, the Air Force will be able to fly five 300- cubic-foot containers with the new Advanced Design Refrigeration System 300 (ADR-300).

"It's a large transportation footprint reduction," Mandile said. "The Army and Navy have expressed interest, but it's currently an Air Force program."

Since the old 150-cubic-foot refrigerator hangs over the air transport pallet that integrates with the rail system inside a military aircraft, only three of the five pallet positions are occupied. All five-pallet positions can be occupied by the ADR-300.

The back wall of the ADR-300 container will be set back from the edge of the base. It provides a safety aisle required for air cargo transport and a protective bumper to protect the refrigeration unit from damage during handling.

If pallet rails are damaged, removable rails will allow airmen to swap them in the field instead of sending the entire container to a repair facility.

Transport is easier with forklift pockets on all four sides of the pallet, and metal lifting, hoisting, and tie down rings that are used for helicopter and ground transport. Fewer aircraft are needed to deploy them, and the loads can be better balanced.

Dry-rotted wood and insulation that lost its ability to hold proper temperature were other problems with the aging 150-cubic-foot refrigerators.

"Instead of the loose-fill fiberglass insulation that you'd find in your house, we're using new insulation technology where thermal performance will be significantly improved," Mandile said.

New insulation materials will maintain interior temperatures down to -20 degrees F at an ambient temperature of 125 degrees F and will enable walls to be thinner for extra carrying capacity.

Because of the new container's thermal efficiency, a 3,000 BTU commercial refrigerator can replace the older 5,000 BTU military-specific model used with the 150-cubic-foot containers. It slashes energy consumption by 40 percent and weight in half.

Mandile said the Air Force expects to purchase 375 ADR-300s with production expected to begin in the summer of 2002.

When the requirement calls for mass storage of perishable goods, the Air Force uses the 1,200-cubic- foot prefabricated panel-type refrigerator to perform the job, but deploying it is a chore.

"It's very manpower-intensive to set up and breakdown," Mandile said. "The panels often didn't fit right and are warped or damaged due to rough handling and seal degradation. It allowed heat and moisture to penetrate the panels, causing its internal frame and gaskets to rot."

He added that it also requires more than 2,000 cubic feet of space of shipping containers just to send 1,200 cubic feet of refrigerated space to its destination, which leaves much to improve in transportation footprint and weight reduction. The old panels suffered from rusty hardware as well, and used a foam insulation that will be replaced with new rugged and thermally-superior materials.

The Advanced Design Refrigeration System 1200 (ADR-1200) replaces wood-lined panels and two 10,000 BTU military-specific refrigerators transported in three shipping containers with a single container and one integrated commercial refrigerator.

The ADR-1200 container system uses two aircraft pallet positions in a cargo plane vs. three for the current 1,200- cubic-foot prefabricated refrigerator.

Although an Air Force-led program, the Army has shown interest, said Mandile. The ADR-1200 is intended primarily for long-term bulk storage of temperature-sensitive products in a base camp.

He said the ADR-1200 could be used as a long-term storage container that would be re-supplied from several of the smaller, more mobile ADR-300s or vice versa.

The ADR-1200 can also be deployed full and operate on-the-move if electrical power is available.

Engineers are investigating various designs to adjust the container volume from 700 cubic feet during transport to 1,200 cubic feet after setup. The first prototype should be ready by September 2003 with production set for 2004.

During Operation Roving Sands, a 1999 training exercise in Texas, the need for a more efficient refrigeration system became apparent.

Two single-temperature 8-by-8-by- 20-foot ISO container refrigeration systems were often sent half-full each with fresh or frozen food supplies for cooks feeding soldiers in the field.

The Army determined they needed a system that could freeze and refrigerate simultaneously to support feeding thousands of soldiers in an Intermediate Brigade Combat Team, and found it with the Multi-Temperature Refrigerated Container System (MTRCS).

MTRCS replaces and improves upon the outdated and worn-out single-temperature refrigeration systems.

A moveable insulated partition divides the container into two separate compartments that can be configured to meet the needs of the mission, eliminating wasted space from half-full, single-use systems. Double side doors on the frozen compartment ease loading and unloading.

Furthermore, using a single system solves the problem of coordinating separate shipments of fresh or frozen foods in theater, Mandile said.

The system's commercially-available diesel engine-driven refrigeration can power itself, or an external electrical power source can operate the unit.

The refrigerator and upgraded insulated container allows an internal temperature range of -20 degrees F to 70 degrees F in ambient conditions as high as 125 degrees F.

"They can eat from the outside in," Mandile said about the unit-configured loads used for cooks to plan meals. "They can have the different rations placed in order and take them out as they work along their planned menu."

Stuffed full, the containers can fit 14 pallets of food and feed 800 soldiers for two days.

A prototype container is scheduled for February 2003 with production set to begin in 2004. More than 300 MTRCS are scheduled for procurement.

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