Abstract
Key Words
particulate matter, size distribution, emission testing, PM 10 and diesel vehicles
Abstract
In 2004, fine particulate matter (PM10 , size ≤ 10 microns) is the major air pollution problem in Thailand as same as recent years. The PM10 concentration is increasing rapidly and continuesouly in particular areas such as Samutprakran Province, Bangkok Metropolitan Area (Roadside) and Tambon Napralarn, Amphur Chalermprakiet ,Saraburi Province respectively. The rapidly increasing number of vehicles travelling on the streets and roads in Bangkok Metropolitan Area lead to high concentration of air pollutants in environment particularly TSP and PM10.The major source of air pollution problems in Bangkok Metropolitan Area is a mobile source and it contributes almost 54 % of TSP including CO, NOx and HC inventories as 75 %, 80 % and 87 % respectively (World Bank,2002) and diesel vehicles are responsible for high emissions of PM and NOx. In response to emission control strategies, the Royal Thai government by the Pollution Control Department (PCD) conducted a research focusing on size distribution of PM for diesel vehicles in Thailand with the objectives to study size distribution of PM for diesel vehicles both of light duty diesel and heavy duty diesel differenting engine size,model year,car maker,technology and vehicle age ;and to evaluate an amount of PM emitting from diesel vehicles in Thailand. The experiment was conducted at the PCD Automotive Emission Laboratory,where 50 kms from Bangkok Metropolitan Area. Almost 27 vehicles, 12 of light duty diesel vehicles (LD) and 15 of heavy duty diesel vehicles (HD) were identified as candidates for the measurement of emissions.These vehicles were tested using the chassis dynamometer and constant volume sampler system (CVS). For each vehicle, separate measurements of emission such as HC, CO, NOx, PM and fuel consumption was testing by using Bangkok Driving Cycle. Each vehicle was driven onto the dynamometer, properly secured, and the exhaust sampling system connected. All of the TSP and PM10 were sampling by a filter holder specific only LD and HD test cells. Consistent with standard certification testing procedures for particulates, primary and backup filters collected TSP and PM10 samples from the secondary tunnel. Computerised mass flow controllers were used to measure and regulate sample and dilution-air flow through the filters. Standard gravimetric methods were used for weighing the primary and backup filters. All particle instruments were connected to the secondary tunnel through isokinetic sampling nozzles for each instrument.The sampling filters were wighting and evaluating as gram per cubicmeter unit (g/m3).The PM size distributions and PM mass were evaluated between 0.18 – 18 micron and at 2.608 – 11.674 mg/m3 for LD vehicles and at 2.503 – 14.471 mg/m3 for HD vehicles respectively.Amounts of PM10 were dominated up to 89.41% for LD vehicles and particle sizes at 0.18 – 0.32 microns were dominated up to 20.27%.For HD vehicles, amounts of PM10 were dominated up to 91.77% and the dominant particle size was at 0.56 – 1 micron as 17.82%.