By Otsile Kadiege
With the world’s vehicle population now exceeding 1,4 billion, millions of engines start up daily with varying degrees of exhaust emissions clouding the atmosphere. South Africa contributes 0,79% (11 million) to the world total. As such, all vehicles sold in South Africa from 2008 had to comply with Euro 2 – Euro 3 and 4 have not been compulsory in South Africa while Euro 6 has already been introduced in Europe. Isuzu Motors South Africa now introduces Euro 5 technology into the New Generation (NG) N and F series range of trucks.
Difference between Euro standards and greenhouse gases
The most important distinction between Euro standards and greenhouse gases which are driving both diesel fuel and diesel engine technology is that Euro emission standards impact on quality of air whilst greenhouse gases impact on the climate. The aim of Euro emissions standards is to reduce the levels of harmful exhaust emissions, chiefly: Nitrogen oxides (NOx) Carbon monoxide (CO) and Hydrocarbons (HC). Unlike the emission standards for passenger cars and light commercial vehicles, which are defined by vehicle driving distance in g/km, the emission standards for trucks and buses are defined by engine energy output in g/kWh.
The success of Euro standards is linked to the quality of diesel fuel, particularly the sulphur content ratio. Sulphur oxides are destroyers of filtration equipment. While 50ppm sulphur (parts per million) is now generally available, Regulations (Govt Gazette 40568) will limit sulphur in diesel to 10ppm.
Changes in Isuzu truck engine technology
Significant changes made to the engine technology of Isuzu trucks starts with the common rail, electronically managed diesel engine. Isuzu Euro 5 engines on initial selected models now come with Variable Geometry Turbocharging together with increased injection pressure (up to 2000bar). This means a design that achieves a more rapid boost to increase torque and avoids turbocharger lag. Exhaust Gas Recirculation (EGR) has also been improved on Isuzu Euro 5 engines with a laminate EGR cooler that allows for more effective control of NOx.
The Move to Euro 5 comes with after-treatment in the exhaust system. A combined unit comprising a Diesel Oxidation Catalyst (DOC) and a Particulate Oxidation Catalyst (POC) for the N-Series and DOC for the F-Series ensures that emission is limited to Carbon Dioxide (CO2) and Water (H2O).
The unique advantages of the Isuzu system is that there is no need for any additives such as urea (AdBlue) to make the technology work for a clean exhaust. According to Isuzu, 10ppm diesel is the most effective for trucks with Euro 5 technology however they can still operate with 50ppm diesel.
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