NaturaLINE CO2-based container refrigeration system makes debut

Dec. 1, 2011
Carrier Transicold debuted its container refrigeration system that uses the natural refrigerant CO2 (carbon dioxide) at the Intermodal Europe Show recently,

Carrier Transicold debuted its container refrigeration system that uses the natural refrigerant CO2 (carbon dioxide) at the Intermodal Europe Show recently, one year after the company announced it had developed and begun testing the technology.

Incorporating breakthrough technologies, the new NaturaLINE design has been engineered to deliver efficiencies equal to Carrier Transicold's PrimeLINE unit.

By using CO2 as a natural refrigerant, the NaturaLINE design improves upon the PrimeLINE unit's ability to reduce CO2 emissions 28% compared with previous units. PrimeLINE and now the NaturaLINE unit reduce on-board power generation requirements, helping shipping lines save fuel. This, in turn, helps hold down operating costs and reduce emissions related to power generation.

“Addressing the special thermodynamic properties of CO2 necessitated the development of an innovative refrigerant management system, including a new purpose-built, multi-stage compressor with variable-speed drive, a ‘gas cooler’ with a wrap-around design, and a flash tank,” said Mike Griffin, new product development program manager, Carrier Transicold. “The patented reciprocating multi-stage compressor maximizes capacity and minimizes power consumption.”

NaturaLINE uses two stages of compression, which improves overall efficiency of the unit. Its cylinder unloading capability allows the compressor to save energy in light-load conditions.

The variable-speed drive that controls the compressor is a first for a Carrier container refrigeration unit. The custom-designed drive electronically adjusts compressor speed to provide the precise amount of cooling capacity to meet demand.

NaturaLINE technology replaces the condenser assembly found in conventional refrigeration units with a new heat exchanger called the gas cooler. The gas cooler coil wraps around the fan, maximizing heat-transfer surface area for greater efficiency in a design that is both compact and lightweight.

The flash tank, an entirely new component in a container refrigeration system, is designed to manage the flow and phase change of the refrigerant after leaving the gas cooler. For efficient cooling performance, the patented Carrier design enables final separation of CO2 from its gas phase to the liquid state before entering the evaporator.

NaturaLINE's design remains consistent with Carrier Transicold's other units. The basic frame, evaporator and evaporator fans, and controller and control box are virtually identical to other Carrier Transicold models. The control interface works the same as on other container refrigeration units. Serviceability will be similar to other Carrier Transicold products, and will be supported by a new training program.

Carrier Transicold is a part of UTC Climate, Controls & Security Systems, a unit of United Technologies Corp (NYSE: UTX). For more details, visit