An Efficient Multipollutant System for Measuring Real-World Emissions from Stationary and Mobile Sources

Xiaoliang Wang,Judith C Chow,John G Watson,Steven D Kohl,Steven Gronstal

doi:10.4209/aaqr.2011.11.0187

Abstract

A portable dilution sampling and measurement system was developed for measuring multipollutant emissions from stationary and mobile sources under real-world operating conditions. This system draws a sample of exhaust gas from the source, dilutes it with filtered air and quantifies total volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), sulfur dioxide (SO2), oxygen (O2), particle size distribution, particle number and mass concentrations, and black carbon (BC) concentration at 1–6 sec interval. Integrated samples by canisters and filter packs are acquired for laboratory analyses of VOC speciation, particle mass concentration, light absorption, elements, isotopes, ions, ammonia (NH3), hydrogen sulfide (H2S), sulfur dioxide (SO2), carbon, and organic compounds. Experiments were carried out to evaluate this system. The accuracy of key real-time instruments were found to deviate < ± 12% from references. CO2 was used as the tracer gas to verify the concentration uniformity in the three measurement modules and relative concentration difference was < 5.1%. Instrument response time was tested by emissions from lighting and burning matches. The DustTrak DRX and optical particle counter (OPC) had the fastest response time, while other instruments had 3.5–21.5 sec delay from the DustTrak DRX and OPC. This system was applied to measure emissions from burning pine logs in a wood stove. The real-time data showed flaming, transition, and smoldering phases, and allowed real-time emission ratios to be calculated. Combing real-time data and laboratory analysis, this measurement system allows the development of multipollutant emission factors and source profiles.

Highlights

Real-world emissions represent effluents of multipollutant mixtures as they would appear soon after exiting the source, cooling, and equilibrating to ambient conditions (Cadle et al, 2009; Chow and Watson, 2011)
This system draws a sample of exhaust gas from the source, dilutes it with filtered air and quantifies total volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), sulfur dioxide (SO2), oxygen (O2), particle size distribution, particle number and mass concentrations, and black carbon (BC) concentration at 1–6 sec interval
Engine and vehicle certification tests are performed with an engine or chassis dynamometer (Code of Federal Regulations, 2001a, b, 2002), where the engine or vehicle operates on a prescribed transient cycle or at several steady-state loads

Summary

INTRODUCTION

Real-world emissions represent effluents of multipollutant mixtures as they would appear soon after exiting the source, cooling, and equilibrating to ambient conditions (Cadle et al, 2009; Chow and Watson, 2011). A portable dilution source sampling and measurement system is described here that allows for direct measurements of real-world multipollutant emissions This system harmonizes emission measurements for stationary (Watson et al, 2010; Wang et al, 2011) and mobile (Chow et al, 2010a) sources. The flow rate (5 L/min) through each filter pack is controlled by a feedback loop between the pump (Model B2736, BGI Inc., Waltham, MA) speed and flow meter (Model 41221, TSI Inc.) readings Additional sampling media, such as a 2,4-Dinitrophenylhydrazine (DNPH) cartridge for carbonyls (Fung and Grosjean, 1981), a Tenax cartridge for heavy hydrocarbons (Zielinska et al, 1986; 1994b; Zielinska and Fujita, 1994a), or filter media for additional PM speciation can be added to this module.

Background

Findings

CONCLUSIONS