Relative humidity (RH) levels as low as 50 percent are now achievable with Carrier Transicold's PrimeLINE' container refrigeration units, with no compromise in their industry-leading energy efficiency. Carrier Transicold is a unit of Carrier Corp., the world's leader in high technology heating, air-conditioning and refrigeration solutions, improving the world around us through engineered innovation and environmental stewardship. Carrier Corp. is a business unit of United Technologies Corp.

Low RH is important for shipping certain types of produce, such as ginger and other root crops, onions, garlic and flower bulbs. Keeping things dry can also be helpful when shipping paper products, artwork, pharmaceuticals, electronics and even certain metals that might be prone to surface staining. A new control enhancement provides the lowest humidity level ever achieved by a Carrier Transicold container unit and expands the PrimeLINE unit's dehumidification capabilities over a wider range of operating temperatures.



'Already best-in-class in so many ways, the PrimeLINE unit now offers this extended dehumidification range as a standard feature,' said James Taeckens, senior product manager. 'In addition, this enhanced capability can be added to existing PrimeLINE models when users upgrade to the latest control software.'



Thanks to the PrimeLINE unit's electronic expansion valve, the dehumidification enhancement was done entirely through sophisticated software algorithms. No change to the mechanical design was required.

'Carrier's control software engineers were able to achieve exceptionally consistent humidity levels, even at 50 percent RH,' Taeckens added. 'This was achieved without consuming any more energy than was needed to achieve the previous low-humidity threshold of 65 percent.'



To achieve low humidity levels, some competitive offerings with mechanical thermo-expansion valves or add-on heat exchangers require greater energy consumption without providing the same consistent humidity and temperature tolerances offered by PrimeLINE units. This was demonstrated in recent field tests conducted by two shipping lines. In one test, a competitive unit required 37 percent more energy to achieve 72 percent RH at 5 C. In other tests, the competitive units could not even reach specified humidity at setpoints of 50 percent RH at 5 C and 75 percent RH at 15 C, even though the PrimeLINE easily could. The upper dehumidification range of the PrimeLINE unit remains 95 percent RH.



The PrimeLINE unit was developed to help shipping lines conserve fuel and reduce emissions related to shipboard power generation. It is the industry's most energy efficient container refrigeration unit. The PrimeLINE unit offers exceptional pull-down capability and the highest deep-frozen capacity of any unit using non-ozone-depleting R-134a, the refrigerant with the lowest global warming potential of all contemporary container refrigerants.