Revealing the new unit, David Appel, president, Carrier Transicold, said, “NaturaLINE provides the global shipping industry with the most environmentally sound alternative for refrigerated transport,” adding that it is the only system to offer a natural refrigerant-based solution.
Carrier claims that by using CO2 its new unit delivers efficiencies equal to and improving upon its PrimeLINE unit, which itself reduces carbon dioxide emissions by 28% compared to previous units. Both units also 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.
“NaturaLINE demonstrates how technological innovation can reduce the impact on climate change, continuing Carrier’s long-standing commitment to providing sustainable solutions,” Appel said.
“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, the company’s new product development programme manager. “The patented reciprocating multi-stage compressor maximises capacity and minimises power consumption.”
NaturaLINE uses two stages of compression, including a unique cylinder unloading capability that allows the compressor to save energy in light-load conditions. The custom-designed variable-speed drive controlling the compressor, electronically adjusts its speed to provide the precise amount of cooling capacity to meet demand, saving considerable energy compared to conventional units.
In addition, the condenser assembly found in conventional refrigeration units has been replaced by a new compact and lightweight ‘gas cooler’ heat exchanger, which coil wraps around the fan, maximising the heat-transfer surface area for greater efficiency.
“The gas cooler makes the overall refrigeration system more versatile in responding to the thermodynamic properties of CO2, providing gas cooling after each compression stage for better efficiency,” added Griffin.
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 design enables final separation of CO2 from its gas phase to the liquid state before entering the evaporator.
While introducing many industry firsts, the NaturaLINE design remains consistent with Carrier’s other units, with the basic frame, evaporator and fans, along with the controller and control box, virtually identical to existing models.