An optional engine emissions system (EES), capable of reducing diesel particulate mass from trailer refrigeration unit exhaust by more than 98%, has received conditional verification from the California Air Resources Board (CARB), Carrier Transicold says. 

The CARB level 3+ verified diesel emissions control (VDEC) device can be included on new trailer refrigeration units or added later for users who do not initially require it, the company says. A Level 3+ VDEC device reduces particulate emissions to CARB’s ultra-low emissions requirements, while also reducing nitrogen oxides. 

“Carrier Transicold’s latest trailer refrigeration unit engines are already certified for ‘evergreen’ compliance with the 2013 EPA Tier 4 standard for engines less than 25 horsepower, allowing for indefinite use throughout North America, except in California,” said David Kiefer, director of marketing and product management, Carrier Transicold. 

“In California, CARB uniquely requires that a VDEC strategy be applied to units in this horsepower class for use in the state beyond the initial seven years.” 

EES uses a diesel particulate filter and an oxidation catalyst, engineers explained. An automatic filter regeneration system burns collected diesel soot and controls engine backpressure. The regen system has an engine intake air control valve, a diesel-fuel doser, an oxidation catalyst, and a catalyzed silicon carbide wall-flow filter with an electronic control unit to limit backpressure.  

EES can be fitted to Carrier X4-7300 and 7500 transport refrigeration units, Vector 8500 and 8600MT TRUs, and Carrier UG and RG generator sets equipped with model year 2012, 2013, and 2014 Kubota model V2203L-DI-EF01e engines rated at less than 25 horsepower.  

Retrofits can be done to in-use engines with less than 3,000 hours of operation at time of installation.  New TRUs may be retrofitted with EES concurrent with sale or lease.   

“CARB conditional verification validates the operation and effectiveness of the EES in Carrier’s 2013 Tier 4 refrigeration units,” Kiefer said. “This is a major milestone. It is the first and biggest step toward offering a broader array of CARB-compliant options to our customers.  

“In accordance with CARB protocols, testing on aged trailer unit engines will continue into 2014 to verify EES performance on engines with far more hours of service, so as to eliminate the 3,000-hour provision,” he said. 

More information about units that can use the new engine emissions system is available from Carrier Transicold dealers or at