Refinement of the Legislative Test Cell Conditions Based on Local Real World Ambient Condition

Vehicles are tested in controlled and relatively narrow laboratory conditions to determine their type approval emission values and reference fuel consumption. Some studies have shown that real world driving emissions are much higher as compared to laboratory measurements. The difference was caused by two important factors, i.e. ambient conditions (temperature and altitude) and actual real-world driving cycles. For this reason, the European Commission had constituted a working group which developed a complementary Real-Driving Emissions (RDE) test procedure using the Portable Emissions Measurement Systems (PEMS). RDE test will verify gaseous pollutant and particle number emissions during a wide range of normal operating conditions on the road. In RDE test specific boundary conditions of the temperatures, classified as moderate (0 ≤Tamb < 30), Extended (low): -7 ≤Tamb < 0 and Extended (high): 30 <Tamb ≤35 to cover a wide range of real-world driving in Europe. In India, emission regulations have been implemented from ECE regulation without much customization to Indian ambient conditions and driving cycles. In this study, ambient temperature and humidity of twelve Indian cities were collected, which are having the significant share of the total on-road vehicle population. These ambient conditions were compared with the chassis dynamometer test cell standard condition of 20-30° C and absolute humidity 5.5-18 g/H₂O ( two-wheelers and passenger cars). The new temperature and humidity limits were recommended for Indian base homologation test. The standard and new limits were simulated using International vehicle emission model, and emission deviations were estimated for a most representative two-wheeler category of Indian automotive market. The analysis revealed that Delhi was the worst (within Indian metropolitan) and Bengaluru was the best in all the cities considering the ambient data following within standard limits. In the case of Delhi, around 80% and Bengaluru around 10% data were observed outside the limits of standards boundary conditions.