Tailpipe emission characterizations of diesel-fueled forklifts under real-world operations using a portable emission measurement system

Non-road equipment is one of the key contributing sources to air pollution.Thus,an accurate development of emission inventory from non-road equipment is imperative for air quality management,especially for equipment with a large population such as diesel-fueled forklifts.The objective of this paper is to characterize duty-cycle based emissions from diesel-fueled forklifts using a portable emission measurement system(PEMS).Three dutycycles were defined in this study,including idling,moving,and working(active duty operation)and used to characterize in-use emissions for diesel-fueled forklifts.A total of twelve diesel-fueled forklifts were selected for real-world emission measurements.Results showed that fuel-based emission factors appear to have smaller variability compared to time-based ones.For example,the time-based emission factors for CO,HC,NO,and PM 2.5 for forklifts were estimated to be 16.6-43.9,5.3-15.1,26.2-49.9,5.5-11.1 g/hr with the fuel-based emission factors being 12.1-20.3,4.1-8.3,19.1-32.4,3.5-6.5 g/kg-fuel,respectively.NO emissions appear to be the biggest concern for emissions control.Furthermore,most of the emissions factors estimated from this study are significantly different from those in both National Guideline for Emission Inventory Development for Non-Road Equipment in China and welldeveloped emission factor models such as NONROAD by US EPA.This implies that localized,preferably fuel-based emission factors should be adjusted based on real-world emission measurements in order to develop a representative emission inventory for non-road equipment.

Quantification of emission variability for off-road equipment in China based on real-world measurements

The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system.A total of 53 commonly used equipment for agriculture,base construction,paving construction,and material handling were selected.Time-based and fuel-based emissions were quantified by different duty and engine modes.Three duty modes(idling,moving,and working)were used.Ten engine modes were defined based on normalized engine revolutions-per-minute and manifold absolute pressure,respectively.Composite emission factors taking into account both duty modes and its corresponding time percentage during a typical duty cycle were estimated.Results showed that there existed a large off-road equipment variability in emissions.Depending on duty and engine modes,time-based NO emissions ranged from 3.1 to 237.9,29.1‒1475.6,83.2‒681.6,and 3.2‒385.2 g/h for agriculture,base construction,paving construction and material handling equipment,respectively while for fuel-based NO emissions these ranges were 5.3‒52.0,11.7‒69.0,4.8‒30.8,and 11.0‒54.6 g/kg,respectively.Furthermore,emission factors derived from this study exhibited a much larger variability compared to those used in NONROAD by US EPA and National Guideline for Off-road Equipment of China.This implied that localized measurements of emissions are needed for improvement of accuracy of emission inventory.Furthermore,both equipment types and operations should be considered for development of emission inventory and control strategy.