NOx cutter improves economy
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by Cohn Sowinan III KUM De-NOx will not only cut Nitrogen Oxides (NOx) in a truck's exhaust but its maker, KHM of Doncaster, will guarantee it will improve fuel economy by at least 5%. Without major modification to the engine, the makers claim NOx is reduced by 19.3%, hydrocarbons (TIC) by almost 40% and Carbon Monoxide (CO) by 19% when De-NOx is fitted.
The system uses exhaust heat to produce steam which is mixed with air through a device called an inspirator. This mixture is fed into the inlet air. On turbocharged engines the steam/air mixture feeds in on the air filter side while on naturally aspirated engines it feeds directly into the inlet manifold.
Once in the combustion chamber, the oxygen in the steam helps the fuel droplets to burn more completely, says Professor Gordon Andrews from Leeds University, The steam also lowers the flame temperature, reducing NOx formation and slowing combustion to allow a more complete burn. The water vapour released by this process helps to soften and remove sooty deposits and so clean the engine, says Andrews.
A water tank, one fifth the size of the main fuel tank is fitted (the system uses five parts of fuel to one of water) and the exhaust is modified to include the "boiler", Water from the tank passes through a filter into a float chamber which sets the level in the boiler.
Air drawn in by the depression downstream of the filter creates a slight vacuum to suck in the steam. It can then pass through the turbocharger and charge-cooler radiator.
Each time the fuel tank is filled up, the water tank is topped up with tap water. If the water runs out, the vehicle reverts to its pre-modified condition.
Maintenance is limited to cleaning the water filter at each service, changing the inspirator's air inlet filter every 60,000km and cleaning the sediment filter on the bottom of the boiler every six weeks.
De-NOx sells for .L750 and takes three hours to fit. If it does not result in a 5% fuel economy improvement. KILM will refund the cost and take the equipment away.
Mitchell Technical is marketing the system for trucks and Eco Coach and Bus of Doncaster for PCVs.