Şehir içi yollarda taşıtlardan ileri gelen karbon monoksit kirliliğinin incelenmesi

Abstract

Bu çalışmada, şehir içi yollarda benzinli taşıt- ların meydana getirdiği kirlenmenin derecesi ile kirlen meyi etkileyen faktörler ve şartlar incelenmiştir. Mete orolojik ve taşrt parametrelerinden geliştirilmiş nüme rik model ile kirleticilerin dağılımı tesbit edilmiştir. Birinci bölümde, karbon monoksitin emisyon kaynak ları ve bu durumu etkileyen şartlar araştırılmıştır. Nü merik dispersiyon denklemlerinin çıkarılışı ve Atmosfe rik stabilitenin tesbiti ile ilgili metotlar, denklemler verilmiştir. ikinci bölümde, bölgenin ve caddenin topografik özellikler ile bu çalışmada kullanılan aletler hakkında kısa bilgiler sunulmuştur» Üçüncü bölümde, taşıt ve meteoroloji ile ilgili gözlem sonuçları verilmiştir. Turner ve Pasquill metodu na göre bölgenin atmosferik stabilitesi meteorolojik pa- metrelerden faydalanılarak bulunmuştur. Daha önceki bir çalışmadan faydalanılarak (38) benzinli taşıtlarda, kar bon monoksit emisyonunun hızla değişimi ile ilgili tek bir grafik geliştirilmiştir. Nümerik dispersiyon modelle ri ile paralel ve dikey rüzgarlı haller için karbon mo noksit konsantrasyonu hesaplanmıştır.. Dördüncü bölümde, atmosferde karbon monoksit dağı lımını etkileyen meteorolojik parametreler üzerinde du rulmuştur. Rüzgar hızlarındaki düşmeler, atmosferik sta bilitenin nötr olduğu haller ve taşıt hızlarındaki düşme 1 1 karbon monoksit konsantrasyonunu arttırmıştır» Paralel rüzgarlı haller için, Pabquill atmosferik stabilite sı nıfı ile 18 m. yükseklikteki rüzgar hızına göre nüme rik dispersiyon modeli yardımıyla hesaplanan değerler. 23 sabitesi ile çarpıldığı taktirde gözlenen değerlere yakın sonuçlar bulunmuştur. Dikey rüzgarlı hal için ise, nümerik dispersiyon modelindeki 7 sabitesi yerine 23 le çarpıldığı taktirde teorik neticelerin deney sonuçlarına yakın olduğu görülmüştür " Geliştirdiğimiz model, şehir içi yollara uygulana rak müsbet neticeler alınabilir.

This study has been done at Beyoğlu Street of Is tanbul where the human and the traffic density is too heavy as far as the intensive business activities are concerned. The dispersion of carbon monoxide pollutton caused by cars in the streets of city and the meteorological fac tors which effect that dispersion have been investigated» The pollutive dispersion of carbon monoxide has been de termined by the given mathematical models derived from meteorological and traffic data for the parallel, and cross wind conditions. The calculated and measured values' have been compared. Different coefficients are proposed for the given models which fit experimental values. In the first chapter, the carbon monoxide emission sources and the factors which effect them are explained. The derivation of mathematical dispersion equations and the methods and the equations of the atmospherical stabi lity are also given in this chapter. In the second chapter, topographic properties of the region and the street are given. The equipment used in this research and how they were settled are described. In the third chapter, the observed results related IV with the traffic volumes, carbon monoxide concentration and meteorological variables have been given. The measure ments started in April 1982 and ended in August of the indicated year. Measurements have been carried out during the working hours of a week in each month. By using the results of the meteorological measurements of the men tioned region, the hourly atmospherical stability has been determined by the Turner and Pasquill equations, A single graph has been developed related with the change of carbon monoxide emission according to the speed in the gasoline engines» By using mathematical dispersion models carbon monoxide concentrations have been calculated for parallel and cross wind conditions. In the forth and the last chapter, the previous calculations and measurements have been discussed, gene ral results, original proposals and conclusion have been given. During 8 a"m0 and 6 p.m., the average number of the vehicles passing along the street changes between 22 and 26 per minute. As for the average speed of the vehicles changes between 14 km/hour and 18 km/hour in the mentioned hours. The carbon monoxide concentration measu red at the level of 1.5 meters above the ground changes between 11 and 21 ppm in average in the period of 8 a.m. to 6 p.m. At the mentioned! level, carbon monoxide con centration rises with increasing of the number of the vehicles and/or decreasing of the speed of them. Again V at the 10 and 15 meters nights, according to the measured results, carbon monoxide concentration changes between 7-11 and 6-10 ppm respectively in the working hours » At the same way, the results of carbon monoxide measurements ob tained for 10 and 15 meters levels have been compared with the number and speed of vehicles. It has been seen that carbon monoxide concentration rises with the increasing of the number of the vehicles and/or the decreasing of the speed of them. According to the results of the meteorologic mea surements, the wind speed on the ENE direction is higher than the WSW direction. The average wind speed at the rooftop was 4<,2 meters/sec, The results of the carbon monoxide measurements at 1.5 meters above have been compared with the wind speed measurements» It has been seen that carbon monoxide con centration diminishes as wind speed inreases, By comparings, it has been understood that there is no relationship between carbon monoxide dispersion and relative humidity., According to the results of the meteorologic observations it has been found that the region had an unstable situation. VI When monthly observation values of the carbon rao- moxide concentrations are compared with each other it has been found out that the mentioned concentrations did not change over in the months and the seasons. Thus, carbon monoxide concentration in atmosphere just arises from gasoline engines. By using the known equation of Caline - 2, :^«^^^[«-r-i(^î][-p-t(^A«v-İ^J Vz; and that of Ludwing,. " _ 7-Q 2 2 1/2 (U+0.5) (x + 2 ) + L o it has been seen that, the calculated values for parallel and cross wind cases were very smaller than observed va lues. In the parallel wind case, according to Pasquill's class of the atmospherical stability and the measurement values of the wind speed of the 18 meters night, if the values calculated with the mathematical model of disper sion multiplied by 23, it has been found the values of the carbon monoxide concentration near to those of the experimental results. VM These "result's have been derived from the iol.lowi.iuj express ion.. In the cross wind case, if we use the 2 3 number instead of the number of 7 which is used in the Ludwiny equation, it. was obtained the values which are approxi mate to the experimental resul ts.'l'his can be showed as 1 o I lows ': ? =- :-?:3Q 2 2 1 /2 (LI + O o 5) (x + z ) ' + L The mathematical model developed in this study can be applied to the city streets., Thus, the more positive res u 1 1 s c a n t > e o b t. a. i n e d. The measured values of carbon monoxide concentration on Lr) meters above the ground during the working hours exceed the standart values ol various countries.