Both Composites and Foam Have Roles in Reefer Insulation

Wabash refrigerated trailer under construction. (Wabash National)

Reefers need to be able to keep freight at a specified temperature, but there is more than one way to achieve thermal efficiency.

“Composite materials, when used in the proper location, offer great advantages in several ways,” said Gary Fenton, vice president of engineering at Stoughton Trailers. “One is thermal efficiency.”

In addition to being strong, stable and lightweight, composites are less vulnerable to water damage, Fenton said.

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Layers of Great Dane's ThermoGuard lining. (Great Dane)

“When water damage occurs, trailers take on more weight and they lose strength gradually,” he said. “So composites can be advantageous when used in places that might be subject to water damage.”

Great Dane uses polyurethane foam as an insulating material in addition to a lining made of a fiber-reinforced polymer-resin composite, said Christian Lee, the company’s vice president of engineering.

“We added metal film in the composite lining to prevent outgassing of insulating agents in the polyurethane foam,” he said. “This helps to maintain high thermal efficiency for long periods of time.”

Hyundai Translead is researching a new foaming technique in an effort to save weight, said Jong Seog Lee, vice president of research and development. Instead of using the current high-pressure foaming process, the company is looking at a low-pressure process.

For a 53-foot trailer, the weight savings could be 200 pounds, Lee said. Hyundai Translead expects to begin using this process in the fourth quarter.

Utility Trailer Manufacturing Co. uses a foaming technique called mandrel foaming, said Craig Bennett, senior vice president of sales and marketing for the company. The trailer’s entire shell is built and put on a mandrel for the foaming process.

“We foam the entire trailer — the floor, the roof and the walls,” Bennett said. “We’re 100% sure that there are no voids in the walls, the floor, or the roof of that trailer,” he said, adding this method “yields a 360-degree foam envelope around the entire cargo space.”