Comparative analysis of noise emissions of new European passenger cars

Comparative analysis of noise emissions of new European passenger cars THEODORA KOKKINOU and EFTHIMIOS ZERVAS* Department of Environmental Engineering Democritus University of Thrace Vas. Sofias 12, 600 Xanthi GREECE ezervas@env.duth.gr Abstract: - European new passenger cars have to comply with regulations concerning noise emission. This work analyses the noise emission of all new European passenger cars from 2000 to 2008. This analysis is made according to fuels used (Diesel and petrol passenger cars), the gear box (automatic and manual) and the emission limits (, and ) of the average values of all passenger cars or of the thirteen major firms presented in the European market (,,,,,,,,,,, and ). The correlations between noise and other engine or vehicle parameters are also searched. This analysis shows the major tendencies of noise emission according to the previous parameters. Key-Words: - Noise emissions, passenger cars, Diesel, gasoline, noise regulations, emission regulations 1 Introduction As noise has a direct impact on the human health and living conditions [1], noise emissions from passenger cars (PCs) are regulated in European Union (EU) [2]. The maximum noise emission currently allowed in EU is decibels (db) [2]. As there is an upper noise emission level, all new passenger cars models have to comply with this limit. It must be noticed that the db is a logarithmic unit of measurement and also a relative unit of measurement. A sound of 0 db corresponds to the lower limits of human hearing for someone with good ears. Some examples of noise levels are: human breathing at 3m: about 10 db, rustling of leaves: about 20 db, residential area at night: about 40 db, quite restaurant: about 50 db, pneumatic hammer at 2m: about 100 db, while the limit of pain for humans is about 130 db. The db is referring to the A-weighing curve, which is the noise curve which is supposed to be the curve better adapted to the way human ears analyze noise. As traffic is considered one of the main sources of urban noise pollution, several authors study the urban noise due to traffic, in real cases or modeling [3, 4]. The noise emission of a passenger car depends on several factors. The four main sources of noise are engine, exhaust, air intake and tire-road interface (plus of course wind noise at higher speeds). Some authors study the impact of different parameters, such as fuel on combustion, of different mechanical parts of the engine, of the driving conditions, exhaust emission control etc. on noise emission [5, 6]. For this reason, there are several techniques used to reduce noise from a passenger car, as the use of better fuels or different design of mechanical parts or different material or sound isolation [7, 8]. However, the total noise emission of a passenger car is guided by legislation limits. This work studies the average noise emission levels of European passenger cars, in order to find the impact of each technology (Diesel, petrol, automatic or manual gear box, exhaust emission levels, ) to total noise emissions. 2 Data and methodology used The data used for this work comes from the internet site of Vehicle Certification Agency (VCA) of UK [9]. This internet site provides the noise emission level of all new passenger cars of the UK market. However, as the UK market is one of the most significant of the EU, we can consider that the main conclusions of this study are also valid in the case of the entire EU market. The data used concern the new PCs certified between 2000 and 2008. The current analysis is initially focused on the average noise emissions of all passenger cars. Then, the noise emissions of diesel and petrol PCs, all, or only with manual or automatic gear box, are analyzed. In a next stage, the same analysis is performed for the main firms presented in the UK market. The analysis is performed for each year and ISSN: 1790-5095 202 ISBN: 978-960-4-125-0

takes into consideration the emission level of each passenger car (, and ). The average values used here are the average values of all models of the UK market and do not take into account the respective sales of each model. As db is a logarithmic unit, those average values express energy intensity. 3 Review of current and past regulations of noise emissions The current value is db and is the same for petrol and Diesel engines [2]. It must be noticed that after three significant decreases of noise emission limits (from 82 to 80 db on 1977, then to 77 db on 1984 and finally to db on 1992), the noise emission limits remain constant for about 16 years. 4 Results and discussion 4.1 Number of passenger cars used In order to have a high degree of confidence on our analysis, the number of PCs used is initially counted. The number of the PC used is presented in another work [10]. The number of PCs is generally quite significant to avoid statistical errors. 4.2 Analysis of average noise emissions Figure 1 shows the average noise emissions of all new PCs and also of only manual or automatic gear box. Since 2000, average noise emissions remain remarkable constant around -.5 db for all type of vehicles. There is practically no difference between, or PCs. In average, PCs with automatic gear box have 0.5-1 db lower noise emissions than the PCs with manual gear box. This difference decreases with exhaust emissions limits: from 1.25 db in the case of PCs, the average difference passes to 0.84 db in the case of PCs and 0.43 db in the case of PCs. Figure 2 shows that there is a slight decrease of average noise emissions in the case of Diesel PCs as a function of emission technology (.0,.53 and.98 db respectively for the, and PCs). Diesel PCs with automatic gear-boxes have lower noise emissions of 0.5-1.0 db than those with manual ones. Figure 3 shows that the opposite trend is observed in the case of petrol PCs: PCs have higher noise emissions than the ones:.4,.1 and.4 db respectively for the, and PCs. As in the case of average noise emissions of all vehicles, petrol PCs with automatic gear-boxes have lower noise emissions of 0.5-1.0 db than those with manual ones. Noise emissions (db) Manual, auto All E2, m E3, m E4, m E2, a E3, a E4, a Figure 1. Noise emissions of all PC models used (all, manual, auto). Noise emissions (db) Diesel manual, auto Diesel all E2, m E3, m E4, m E2, a E3, a E4, a Figure 2. Noise emissions of all Diesel PC models used (all, manual, auto). The difference between Diesel and petrol PCs is not very high: Diesel PCs have in average about 0.05-0.8 db higher noise emissions than petrol PCs. In the case of Diesel PCs, there is a small impact of emission legislation, as PCs have a little lower noise emissions than PCs. This is due to manual gear box Diesel PCs, as and automatic ones have very similar noise emissions. The opposite trend is observed in the case of gasoline PCs: PCs have (very little) higher noise emissions than the ones and this is mainly due to automatic PCs. The difference between manual and automatic gear box is almost independent of the exhaust emissions limit in the case of Diesel PCs; however, there is a clear tendency in the case of ISSN: 1790-5095 203 ISBN: 978-960-4-125-0

petrol PCs: this difference is 1.2, 0.76 and 0.36 db respectively for the, and PCs. Noise emissions (db) Petrol manual, auto Petrol all E2, m E3, m E4, m E2, a E3, a E4, a Figure 3. Noise emissions of all petrol PC models used (all, manual, auto). 4.3 Analysis of each firm The previous results showed that average noise emission is just below the regulatory limits and quite constant during last years. However, this is not the case of each of the major firms of the EU new PC market (figure 4). Noise emission, all PCs, 2008 (db) All Diesel Petrol FORD TOYOTA RENAULT NISSAN MERCEDES CITROEN SEAT AUDI FIAT OPEL PEUGEOT Figure 4. Noise emissions of all PC models of the main firms of EU market (all, Diesel, petrol). Taking into account all models,, and have the passenger cars with the lower noise emissions, while, and have those with higher ones emissions. Generally, Diesel PCs have a little higher average noise emissions; however, a close analysis of each firm shows that several firms have higher average petrol emissions than the Diesel ones. This is the case of,,,, and. Looking at only the average noise emissions of all Diesel or petrol models (figures 5-6), the general classification does not changes significantly. In the case of all Diesel PCs, and have the lower emissions, while, and have again the higher ones. PCs with manual gear box have generally higher noise emissions, even in average 2.6 or 3.0 db as in the case of and. Generally, this difference of average values remains to 0.6-1.6 db. The average noise emissions of three firms,, and are higher in the case of PCs with manual gear boxes. Noise emission, Diesel PCs, 2008 (db) FORD TOYOTA NISSAN Diesel All Diesel manual Diesel auto RENAULT MERCEDES AUDI SEAT CITROEN FIAT OPEL PEUGEOT Figure 5. Noise emissions of all Diesel PC models of the main firms of EU market (all, manual, auto). In the case of petrol PCs,, and have the lowest noise emissions, while, and the highest (figure 6). PCs with manual gear boxes have again higher emission than those equipped with automatic ones, generally by 0.5 to 1.8 db. Only the automatic models of have higher average noise emissions (however very slightly, only 0.02 db) than those of the manual ones. The values of all firms have some fluctuations from one year to another, but generally the average values remain quite constant (figure 8). The firms with other clear trends are found only in the case of PCs:, and with decreased trends and and with increased ones. ISSN: 1790-5095 204 ISBN: 978-960-4-125-0

Noise emission, petrol PCs, 2008 (db) RENAULT TOYOTA Petrol all Petrol manual Petrol auto FORD NISSAN CITROEN SEAT FIAT OPEL MERCEDES AUDI PEUGEOT Figure 6. Noise emissions of all petrol PC models of the main firms of EU market (all, manual, auto). Noise emission, all PCs (db) Figure 8. Evolution of noise emissions of all PC models of the Looking only in the case of Diesel PCs, there are also some fluctuations from year to year, but once again the average values remain quite constant (figure 9). Some exceptions are the following. is the only firm with decreased values in time in the case of PCs, while, and have increased ones. and have decreased values in time in the case of PCs, while and increased ones. All other firms have quite constant average values, not without some fluctuations. Noise emission, Diesel PCs (db) Figure 9. Evolution of noise emissions of all Diesel PC models of the In the case of Diesel PCs equipped with manual gear boxes, is again the only firm with decreased trend in the case of PCs, while, and with increased one (figure 10). is the only firm with decreased values in the case of automatic PCS and, and with increased ones (figure 11). In the case of PCs, only has clearly decreased values and increased ones in the case of manual PCs (figure 10), while in the case of automatic PCs, has decreases and and increased ones. In all other cases, the average noise emission remains quite constant in time (not without some fluctuations). Looking now only in the case of petrol PCs, there are again some fluctuations from year to year, but, generally, the average values remain again quite constant (figure 12). Some firms show some clear tendencies. and have decreased average values of noise emissions in time in the case of PCs, while have increased ones. has decreased average values in time in the case of PCs, while, and increased ones. All other firms have quite constant average values (with some fluctuations). Figure 11 shows the variation of the average noise emissions of the models of each firm. ISSN: 1790-5095 205 ISBN: 978-960-4-125-0

Noise emission, Diesel manual PCs (db) Figure 10. Evolution of noise emissions of all Diesel PC models equipped with manual gear box of the Noise emission, Diesel auto PCs (db) Figure 11. Evolution of noise emissions of all Diesel PC models equipped with automatic gear box of the In the case of petrol PCs gear boxes, and are the only firms with decreased trends in time in the case of PCs equipped with manual and automatic gear boxes, while with increased one in the case of manual PCs and and in the case of automatic ones (figures 13 and 14). In the case of PCs, only has clearly decreased values in time in the case of PCs with automatic gear boxes. Decreased tendency have, and in the case of manual PCs, while, and in the case of automatic ones. Noise emission, petrol PCs (db) Figure 12. Evolution of noise emissions of all petrol PC models of the Noise emission, petrol manual PCs (db) Figure 13. Evolution of noise emissions of all petrol PC models equipped with manual gear box of the ISSN: 1790-5095 206 ISBN: 978-960-4-125-0

Noise emission, petrol auto PCs (db) Figure 14. Evolution of noise emissions of all petrol PC models equipped with manual gear box of the 4.4 Correlations between noise emissions and vehicle characteristics The correlations between noise emission and the other characteristics of the PCs studied here are examined. No evident correlation is found between noise emission level and exhaust emissions of regulated pollutants or of CO 2, and of engine capacity of each PC. 5. Conclusion Since 2000, average of all car models noise emissions remains constant around db. There is no difference between, or PCs. PCs with automatic gear box have 0.5-1 db lower noise emissions than the PCs with manual gear box. There is a slight decrease of average noise emissions in the case of Diesel PCs as a function of emission technology. The opposite trend is observed in the case of petrol PCs. Diesel and petrol PCs with automatic gear boxes have slightly lower noise emissions than those with manual ones. The difference between Diesel and petrol PCs is only 0.05-0.8dB. However significant differences exist between each firm. Taking into account all models,, and have the passenger cars with the lower noise emissions, while, and have those with higher ones emissions. Generally, Diesel PCs have a little higher average noise emissions; however, some firms have higher average petrol emissions than the Diesel ones. Looking at only the average 2008 noise emissions of all Diesel or petrol models, the general classification does not changes significantly. The values of all firms have some fluctuations from one year to another, but generally the average values remain quite constant. No correlation is found between noise emission level and exhaust emissions of regulated pollutants or of CO 2, and of engine capacity of each PC. The above results shows that all firms have models with noise emissions just below the legislation limits and there is no clear tendency of decrease of noise emissions. References: [1] Lipfert, F.W., Wyzga, R.E, (2008), On exposure and response relationships for health effects associated with exposure to vehicular traffic, J. Exp. Scie. Environ. Epidem., 18 (6), 588-599. [2] European Directive /157, http://ec.europa.eu/enterprise/automotive/directiv es/vehicles/dir_157_cee.html. [3] Shaikh, G.H., Ahmad, T., Islam, K. (2006), Traffic noise in Lahore City, Pakistan. Part II. Vehicular contribution to traffic noise, Pak. J. Scie. Ind. Res.49 (4), 256-260. [4] Rajakumara, H.N., Gowda, R.M.M., Simha, L.U. (2004), Traffic noise prediction model at gradients of the highway, Advances in Transport, 16, 795-799. [5] Wang, Y., Zhou, L.B. (2007), The effect of two different kinds of vegetable oil on combustion and emission characteristics of a vehicle dimethyl ether engine, Proc. Instit. Mech. Engin., Part D: J. Autom. Engin., 221(11), 1467-14. [6] Torregrosa A.J., Broatch A., Martín J., Monelletta L. (2007), Combustion noise level assessment in direct injection Diesel engines by means of in-cylinder pressure components, Meas. Sci. Technol., 18, 2131-2142 [7] Zschau A., Becker K., Bourdon R. (2004), Reducing noise development in vehicles, Kunststoffe Plast Europe, 94(11), 112-116.. [8] Pinto C.A.D., Dias D., Walter J., (2008), Application of Six Sigma Methodology on Reducing the Noise Level on Alternators, SAE Technical Paper Series 2008-36-0327. [9]Car Fuel Data (www.vcacarfueldata.org.uk/) [10] Kokkinou Th., Zervas E., (2009), Comparison between the exhaust emissions of regulated pollutants and CO2 and regulations limits of new European passenger cars,, SAE Technical Paper Series 2009-01-1802 ISSN: 1790-5095 207 ISBN: 978-960-4-125-0