2426
Energy & Fuels 2006, 20, 2426-2431
Interlaboratory Study of the Exhaust Gas Particle Number Measurement Using the Condensation Particle Counter (CPC) E. Zervas,*,† P. Dorlhe`ne,† L. Forti,‡ C. Perrin,‡ J. C. Momique,§ R. Monier,§ H. Ing,| and B. Lopez| Renault, 1, Alle´ e Cornuel, 91510 Lardy, France, Institut Franc¸ ais du Pe´ trole (IFP), 1 et 4 AVenue du Bois Pre´ au, 92500 Rueil-Malmaison, France, PSA Peugeot Citro¨en, 18, rue des FauVelles, 92250 La Garenne-Colombes, France, and Union Technique de l’Automobile, du Motocycle et du Cycle (UTAC), Autodrome de Linas-Montlhe´ ry, 91310 Montlhe´ ry, France ReceiVed April 27, 2006. ReVised Manuscript ReceiVed September 7, 2006
Four laboratories, Institut Franc¸ ais du Pe´trole (IFP), PSA Peugeot-Citroe¨n, Renault, and Union Technique de l’Automobile, du Motocycle et du Cycle (UTAC), have conducted an interlaboratory test to evaluate the performances of the condensation particle counter (CPC). The technical program was based on tests carried out on four passenger cars, one gasoline and three diesel ones, tested on the New European Driving Cycle (NEDC). The regulated pollutants are also measured, as indicators of test repeatability and good working conditions. The 1.96RSD reproducibility values of the total particle number determined by CPC on NEDC are 87, 58, 41, and 220%, respectively, for the Euro4 gasoline, Euro3 diesel, Euro4 diesel, and Euro3 diesel plus DPF (diesel particulate filter) vehicles. The CPC repeatability and reproducibility are poorest at lower particle numbers. The CPC performances, in terms of reproducibility, are comparable but generally not much better than the reproducibility of particulate matter emissions determined by the gravimetric method.
Introduction Currently, there are many methods for the determination of particle number and/or distribution. The most common methods used in the case of vehicle exhaust gas are the electrical lowpressure impactor (ELPI),1-4 scanning mobility particle sizer (SMPS),5 and particle counters,6,7 but many others are also reported. A description of several analytical instruments can be found in the works of Burtscher8,9 and Mohr et al.10 SMPS has a very good particle size resolution; however, the quite long time resolution (some minutes) of this instrument is insufficient for transient particle measurement on the New European Driving Cycle (NEDC). ELPI has a sufficient time * To whom correspondence should be addressed. Telephone: +331-76-87-84-77. Fax: +331-76-87-82-92. E-mail: efthimios.zervas@ renault.com. † Renault. ‡ Institut Franc ¸ ais du Pe´trole (IFP). § PSA Peugeot Citro ¨ en. | Union Technique de l’Automobile, du Motocycle et du Cycle (UTAC). (1) Keskinen, J.; Pietarinen, K.; Lehtimaki, M. J. Aerosol Sci. 1992, 23, 353-360. (2) Khalek, I. A. SAE Technical Paper Series 2000, 2000-01-2001. (3) Witze, P. O.; Chase, R. E.; Maricq, M. M.; Podsiadlik, D. H.; Xu, N. SAE Technical Paper Series 2004, 2004-01-0964. (4) Zervas, E.; Dorlhe`ne, P.; Daviau, R.; Dionnet, B. SAE Techical Paper Series 2004, 2004-01-1983. (5) Wang, S. C.; Flagan, R. C. Aerosol Sci. Technol. 1990, 13, 230240. (6) Willeke, K.; Baron, P. A. Aerosol Measurement, Principles, Techniques and Applications; Van Nostrand Reinhold: New York, 1993. (7) Hinds, W. C. Aerosol Technology; J. Wiley and Sons: New York, 1999. (8) Burtscher, H. Tailpipe Particulate Emission Measurement for Diesel Engines. Swiss contribution to GRPE PMP, 2001, http://wanda.fhaargau.ch/ iss/veroeffentlichungen/tailpipe-emissionmeasurement.html. (9) Burtscher, H. J. Aerosol Sci. 2005, 36, 896-932. (10) Mohr, M.; Lehman, U.; Rutter, J. EnViron. Sci. Technol. 2005, 39, 2229-2238.
resolution (1 s), but its size resolution is lower than that of SMPS (ELPI has only 12 stages for the particles from 7 nm to 10.24 µm, while SMPS has 128 channels for the particles from 10 to 500 nm). Another, more recent instrument, is the engine exhaust particle sizer spectrometer (EEPS), which has a sufficient time resolution for measurements on cycles and a size resolution between that of ELPI and SMPS. The performances of this instrument are presented elsewhere.11 If the particle-size distribution is ignored, the total exhaust particle number on steady speeds and cycles can be measured by a condensation particle counter (CPC),12-14 which can determine the total particle number but not the size distribution of exhaust particles. The detailed operation principle of CPC is reported in several studies.6,7,9,10,15,16 The present work presents an interlaboratory study for the evaluation of CPC performances. Four laboratories, Institut Franc¸ ais du Pe´trole (IFP), PSA Peugeot Citroe¨n, Renault, and Union Technique de l’Automobile, du Motocycle et du Cycle (UTAC), participated in this study. The repeatability and reproducibility of the total particle number of a gasoline and three diesel passenger cars (PCs), measured by CPC on the NEDC, are evaluated and discussed here. The definitions of repeatability and reproducibility are given in the Experimental Section. The repeatability and reproducibility are examined on the entire NEDC and also at the urban (UDC, Urban Driving (11) Zervas, E.; Dorlhe`ne, P. Aerosol Sci. Technol. 2006, 40, 977-984. (12) ACEA program on emissions of fine particles from passenger cars 2, Report, July, 2002, www.acea.be. (13) Schaberg, P. W.; Zarling, D. D.; Waytulonis, R.W.; Kittelson, D. B. SAE Technical Paper Series 2002, 2002-01-2727. (14) Anderson, J.; Preston, H.; Warrens, Ch.; Brett, P. SAE Technical Paper Series 2004, 2004-01-1989. (15) Pui, D. Y. H.; Chen, D. Direct-Reading Instruments for Analyzing Airborne Particles. In Air Sampling Instruments; ACGIH: Cincinnati, OH, 2001; Chapter 15, pp 377-414. (16) Kasper, M. SAE Technical Paper Series 2004, 2004-01-0960.
10.1021/ef060180j CCC: $33.50 © 2006 American Chemical Society Published on Web 10/17/2006
Exhaust Gas Particle Number Measurement Using CPC
Energy & Fuels, Vol. 20, No. 6, 2006 2427
Figure 1. Experimental setup of this study. Table 1. Main Characteristics of the Vehicles Useda
vehicle inertia (kg) fuel emission limits after-treatment devices
gasoline
diesel1
diesel2
diesel3
Renault Clio 1020 gasoline Euro4 TWC
Peugeot 307 1360 diesel Euro3 DOC
Renault Laguna 1360 diesel Euro4 DOC
Peugeot 607 1600 diesel Euro3 DOC plus PF
a TWC, three-way catalyst; DOC, diesel oxidation catalyst; DPF, diesel particulate filter.
Cycle) and extra-urban (EUDC, Extra-Urban Driving Cycle) parts of the cycle. More details about NEDC and its parts can be found in the European Directive 70/220.17 ELPI is also used, to allow for a comparison of the results of the present study with the results of the interlaboratory exercise conducted previously to determine the performances of ELPI.18 CPC measurements of several engines or vehicles are reported by other authors, such as Lehman et al.,19 Mohr et al.,20 and Kinsey et al.21 However, the above three authors worked on heavy-duty engines and in one laboratory only; therefore, they do not report reproducibility values. Lehman et al.19 gives some repeatability results; however, because this author worked on heavy-duty engines, his results cannot be directly compared with the results of this study. Experimental Section Four PCs were used in this study: a Euro4 gasoline PC operating under stoichiometric conditions (called “gasoline”), a Euro3 diesel PC (called “diesel1”), a Euro4 diesel PC (called “diesel2”), and a Euro3 diesel PC equipped with a diesel particulate filter (DPF, called “diesel3”). All four vehicles are tested in all four laboratories, except the diesel3 vehicle, which, for technical reasons, is tested by only three laboratories. Table 1 shows the main characteristics of these vehicles. Fuels with less than 10 ppm of sulfur were used for this study. The same lubricant, containing
