Carrier Transicold uses CO2 as refrigerant

   Carrier Transicold said it debuted a refrigerated container that uses carbon dioxide as a refrigerant gas on Tuesday at the Intermodal Europe Show in Hamburg, Germany.
   The company said the new “NaturaLINE” container is engineered to deliver efficiencies equal to its existing “best-in-class” refrigerated container PrimeLINE. It also noted that if the gas leaks, it would cause far less global warming than conventional refrigerants.
   “We completed successful demo unit trials last year, extensive lab & full-scale live testing this year, and we are proceeding with field trials,” said Jon Shaw, a spokesman for Carrier. ” Based on the results of the field trials we will commercially launch the NaturaLINE unit.”  
   He said “pricing has not yet been set. However, we do expect the NaturaLINE unit to sell at a premium over current models.”
   Carrier has successfully applied carbon dioxide in stationary refrigeration applications, with more than 300 retail installations in northern Europe to date, said Shaw.
   Carbon dioxide is a non-ozone chemical and has a much lower “global warming potential” (GWP) –a measure of how much heat it traps if released into the atmosphere than conventional refrigerants. Carbon dioxide has a GWP of one compared to 1,300 for R-134a and 3,260 compared to R-404A.
   James Braun, a professor of mechanical engineering at Purdue Engineering, said the main impetus for use of carbon dioxide as a refrigerant is global warming, and that a secondary consideration is a reduction in the size and weight of heat exchangers. But he said there are some disadvantages, including lower efficiency and higher pressures and therefore higher initial costs.
   A press release from Purdue over a decade ago noted that researchers were making progress in perfecting automotive and portable air-conditioning systems using carbon dioxide as a refrigerant instead of conventional, synthetic global-warming and ozone-depleting chemicals.
   Purdue said carbon dioxide was the refrigerant of choice during the early 20th century but was later replaced with manmade chemicals. It said carbon dioxide might make a comeback, because of technological advances such as extremely thin yet strong aluminum tubing.
   Carrier said that in order for carbon dioxide to work as a viable refrigerant for container refrigeration, Carrier developed several new components including including a wrap-around gas cooler coil, a new purpose-built multi-stage compressor with variable-speed drive and a flash tank.