Something New on the Horizon
Shipping Company’s Need Sparks Development of Dual-Temp Units
The ability to haul cargo at two different temperatures simultaneously has long been appreciated by the trucking industry. For trucks and trailers, separate compartments for frozen and perishables are especially handy for just-in-time delivery of food to restaurants, grocery and convenience stores, where turn-over is fast and storage space is at a premium.
Although Carrier introduced its first multi-temperature system for vehicle refrigeration in 1967, until recently Carrier’s container customers only required single-temperature units. But when a shipping line recently requested a multi-temperature unit, Carrier delivered in short order.
Horizon Lines LLC turned to the experts at Carrier with this special request. Based in Charlotte, N.C., Horizon is one of the leading Jones Act container shipping and logistics companies, operating 16 U.S.-flag vessels on routes linking the continental United States with Alaska, Hawaii, Guam and Puerto Rico.
“They asked us to develop a special unit for them because several of their customers had specialized needs,” said David Smith, Carrier product manager.
According to Jim Canterbury, Horizon’s corporate maintenance manager, the company approached Carrier because “Carrier has always built an outstanding unit.”
Carrier’s design and engineering teams jumped at the opportunity, and the fruit of their labor is the new ThinLINE™ Dual-Temp unit.
“Combining components we had readily available, we created a production-ready design in an expedited timeframe,” Smith said. The design team determined that with modifications to the electronics, the ThinLINE unit was up to the task. All that was needed was a second evaporator.
A Different Design From Familiar Components
A key difference between a single-temperature system and any multi-temperature system is that a remote evaporator is required to handle the refrigeration needs of the second compartment. The ThinLINE unit’s built-in evaporator serves the fore compartment, while the remote evaporator serves the aft.
To meet the need, Carrier’s single-discharge MVD 1100 truck/trailer remote evaporator was modified for compatibility with the ThinLINE unit’s R-134a refrigerant. The evaporator mounts on the ceiling of the aft compartment connected to the ThinLINE unit by appropriate refrigerant lines, drain lines and control wiring.
An insulated movable bulkhead, included as part of the package, creates two compartments within Horizon’s 40-foot containers.
As a result of this initiative, Horizon Lines was able to deliver on its customer requests, and Carrier is now the only original equipment manufacturer that offers a dual-temperature solution made especially for the marine container market.
“Carrier engineers from all levels and locations supported and worked very hard in the development of the unit,” Canterbury observed. “They worked closely with Horizon Lines Corporate Maintenance and the reefer box manufacturer to ensure Horizon Lines received the very best product.”
Although the units were put into service early in 2006, Canterbury noted, “The amazing fact is that the Carrier engineers continue to track and monitor the operations looking for any problems and for future improvement.”
Said Smith, “It’s just a great example of how Carrier’s breadth of engineering expertise and manufacturing resources can be brought together to create a new product that meets a customer’s contemporary needs in a relatively short time.”
New ThinLINE™ Dual-Temp Unit
Two Containers in One!
The latest addition to Carrier Transicold’s container refrigeration line-up has a split personality.
The new ThinLINE™ Dual-Temp unit offers the ability to cool one part of a container and freeze another. Or, if refrigerating one compartment and heating the other is needed, it can do that too.
“It’s one of the most versatile container refrigeration systems ever developed by Carrier,” said David Smith, senior product manager. “It addresses the fact that one-size does not fit all needs.”
The ThinLINE Dual-Temp unit installs on a 40-foot high-cube (HC) container and gives the ability to split the container into two refrigerated compartments of variable size or be used as a single-compartment container.
An insulated moveable bulkhead partitions the container into two sections. The bulkhead slides along a track and adjusts six- feet from center in either direction. This means the compartment can be divided into two 20-foot compartments or into two compartments of variable size up to a 14-foot / 26-foot combination.
Either one or both of the sections can be cooled independently. Hinged at the top, the bulkhead swings up for single-compartment operation, allowing the container to serve as a standard 40-foot HC refrigerated unit.
The ThinLINE Dual-Temp host unit is nearly identical to a regular ThinLINE unit. The host unit’s evaporator can either chill or freeze the front compartment. Cooling the rear compartment is achieved with a second evaporator, mounted from the ceiling and protected by a steel cage.
Also included in the assembly are condensate drain lines and refrigerant lines for the remote evaporator, and a wiring harness sheltered in a recessed channel in the container ceiling.
The digital displays on the ThinLINE Dual-Temp unit’s MicroLink™ controller toggle between readings for the front or rear compartment so operators can program and monitor both from a single control.
The front compartment delivers the standard frozen/perishable setpoint range of 30°C to 30°C (-22°F to 86°F) when dual-temp mode is not activated. The range is from 30°C to -1°C (-22°F to 30°F) when operating in dual-temp mode. The rear compartment offers a perishable-only range of -2°C to 21°C (28°F to 70°F).
“The unit will be especially practical for applications where currently less than full 40-foot units or two 20-foot units are being used,” said Smith. “This may include applications in remote locales such as Alaska or island hoppers in the Pacific Rim and Caribbean.”
“In those instances, there may be demand for 40 feet worth of cargo but it’s mixed between frozen and perishable,” Smith said. “Rather than having to pay the rates for two 20-foot reefers or one 20- and one 40-foot unit with partial loads at different temperatures, they could pay something less for the benefit of using a single container.”
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