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Righteous reefers

MINNEAPOLIS, Minn. - Achieving proper cooling capacity in your refrigerated trailers is obviously critical, however, there are a number of ways to get there.Before a reefer dealer gets around to makin...


COOL: Thermo King says its dealers have a computer program to accurately find a trailer's box loss.
COOL: Thermo King says its dealers have a computer program to accurately find a trailer's box loss.

MINNEAPOLIS, Minn. – Achieving proper cooling capacity in your refrigerated trailers is obviously critical, however, there are a number of ways to get there.

Before a reefer dealer gets around to making their sales pitch, they’d better know what your desired application is going to be. If not, get up and walk away, because spec’ing the right reefer requires a lot of personalized information.

“Application being, what kind of products are they going to haul, for how long of a period, what are the set points of the products they’ll be transporting, and where are they going to run?” says Douglas Lenz, a trailer product manager with Thermo King. He says knowing the thickness of the trailer’s walls and roof allows a reefer dealer to calculate that trailer’s efficiency.

“The more insulation you add, the easier it is for the refrigeration unit, but it also adds weight,” says Lenz. Commonly referred to as box loss, the trailer’s efficiency over time will narrow down the number of choices when making the call on the actual reefer unit.

From there the formula is relatively simple: (Trailer Efficiency) x (Outside Temperature – Inside Temperature) = Cooling Capacity.

So for example, say you had a Canadian fresh produce hauler who only does local runs. Lenz explains that if that O/O had a trailer with a box loss of 200 Btu/hr/degrees F, you would multiply that by about 45F, which is the difference of an average warm day (80F) less the temperature the load needs to be cooled down to (35F). In this fictional example, the trucker would need to spec a reefer unit capable of delivering 9000 Btu/hr at an ambient temperature of 80F.

As a reefer ages, it loses efficiency as oil sediment in the system clogs and fouls its ability to cool. But a Calgary-based company says it has a solution. Magnetech says its CUE-factor, a polarized refrigerant oil additive (PROA) provided MacKinnon Transport with a significant boost in thermal transfer efficiency.

The U.S. Federal Energy Management Program, which conducted testing of its own, reports these gains to be anywhere from 20 to 30 per cent. The technology has also been tested and endorsed by the U.S. Department of Energy and the American Society of Heating, Refrigeration and Air Conditioning Engineers, explains Magnetech. n


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