Thermo King's new Greentech diesel engine produces 0.28g/kWh, which is low enough to comply with EU Stage IV limits. The engine can run on biodiesel and noise levels are lower. "The decibel level remains the same, but we have changed the frequency so it is less noticeable to the human ear," explains Alberto Rouco of Thermo King.
Environmental concerns have renewed interest in direct-drive refrigeration units for larger bodies. Operators often think alternator-driven units do not have the same capacity as diesel units, admits Rouco, or are less reliable. "The compressor is the key both to capacity and to reliability." Thermo King uses reciprocating compressors, he explains, which are better suited to producing large capacity cooling in a small unit than swash-plate compressors.
"Alternator-driven direct drive units not only produce less emissions than a diesel-powered unit, the power comes from an engine that meets even stricter emission targets than Stage III," explains John Winter, MD of Frigoblock UK. Its hybrid drive HD25 unit combines alternator drive with an independent diesel engine and has an energy efficiency of over 80%. "Fuel consumption is about a third lower on the hybrid engine - about 0.2 litres per hour. That's partly because the compressor is switched off when in normal mode, eliminating the stop-start operation of conventional refrigeration engines."
On the small diesel front, Carrier Transicold is taking the simple approach. Its Neos unit is virtually a plug-and-go unit for car-derived vans. "Fitting time is under ten hours, which keeps the cost down and we have improved the looks," says product manager Andy Jarvis. For larger vans, the latest Vienos unit removes the electric standby option available. "On lots of small vehicle deliveries, the load is already chilled or frozen, so all the refrigeration unit has to do is maintain the product temperature, "points out Jarvis. "Electric stand-by adds weight and cost."
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