New analysis by Dearman suggests that zero-emission transport refrigeration systems could cut overall engine pollution from refrigerated vehicles by up to 93% and have a major impact on air quality. One application of Dearman’s engine technology is to provide high efficiency, zero-emission transport refrigeration units (TRUs). (Earlier post.)
The findings of Dearman’s research indicate that equipping a Euro6-standard 17-tonne rigid body truck with a zero-emission refrigeration system, as opposed to a diesel-powered unit, would cut the vehicle’s overall engine emissions of particulate matter by 93%, and reduce NOx emissions by 73%.
Refrigeration systems on trucks are typically powered by an auxiliary diesel engine. Poorly regulated, these small secondary engines can emit up to six times the NOx and 29 times the particulate matter of a truck’s Euro6 propulsion engine.
The Dearman transport refrigeration system is powered by the expansion of liquid nitrogen. Unlike conventional transport refrigeration units, many of which are able to use subsidized diesel in operation, the Dearman system emits no NOx, no PM, or other pollutants associated with combustion.
|The Dearman system stores liquid nitrogen at ~3bar in a cryogenic vessel. The liquid nitrogen is pumped to ~40bar and transferred to a vaporizing heat exchanger where it provides cooling for the chilled compartment. Approximately two-thirds of the total cooling supplied comes from this source.|
The cryogenic gas is fed into the Dearman Engine—a novel piston engine powered by liquid air or liquid nitrogen (earlier post)—which is used to support ancillary systems such as feed pumps, an alternator and fans for air circulation as well as to drive the compressor of a vapor compression refrigeration cycle that provides additional cooling. One-third of the total cooling supplied comes from this source.
The heat exchange fluid is then reclaimed and used to harvest heat from the condenser of the refrigeration cycle, which has the advantage of approximately doubling its efficiency. The heat exchange fluid is re-used in the engine. The only emission back to the atmosphere is air or nitrogen. Click to enlarge.
The system also offers real CO2 savings over its lifetime and will enable operators to address a large proportion of their fleet’s emissions without having to change the way their fleets function.
To support the delivery of Dearman technology to the market, the company has formed a significant partnership with Hubbard Products Ltd, the UK’s leading transport refrigeration unit integrator. The Dearman transport refrigeration system is undergoing final closed-road testing ahead of commercial deployment in field trials.
A study released last year found that pollution from transport refrigeration could cost European Union countries €22 billion over the next decade, as the EU refrigerated road vehicle fleet grows to almost 1.2 million by 2025. If nothing is done, the environmental and health impacts of emissions of CO2, HFCs, NOx and PM will impose an annual burden of more than €2.5 billion in 2025.