THE ISSUE OF DETERMINING THE COMPOSITION OF EXHAUST GASES BY CALCULATION METHODS

ABSTRACT

The problem of determining the toxicity of vehicle exhaust gases has appeared since the 1960s of the 20th century. To date, the assessment of quality and quantity of harmful gases in the composition of exhaust gases is mainly determined by bench and, more recently, road test methods. Expensiveness of testing equipment, installations, operating materials for them, limited testing methods in ensuring the identity of tests with real operating conditions and other factors require their perfection. They determine the relevance of the task of searching for modern ways to assess the toxicity of car exhaust in different operating conditions. The article is devoted to the development of a calculation method for determining the composition of exhaust gases CO, CH, NOx on the basis of the dependence of gases on the oxygen-fuel mixture.

АННОТАЦИЯ

Проблема определения токсичности выхлопных газов автомобиля появилась с 60-х годов 20 века. Оценка качества и количества вредных газов в составе выхлопных газов по сегодняшний день в основном определяется стендовыми, в последнее время, дорожными тестовыми методами. Дороговизна испытательных оборудований, установок, эксплуатационных материалов к ним, ограниченность методов тестирования в обеспечении идентичности испытаний с реальными условиями эксплуатации и другие факторы требуют совершенства их. Они определяют актуальность задачи поиска современных способов оценки токсичности выхлопа автомобилей в разных условиях эксплуатации. Статья посвящена разработке расчетного метода определения состава выхлопных газов СО, СН, NОx на основе зависимости газов от кислородно-топливной смеси.

Keywords: air-fuel ratios, environmental class, carbon monoxide CO, hydrocarbons CH, nitrogen oxides NOx, engine speed, degree of throttle valve opening position.

Ключевые слова: соотношений воздух-топливо, экологический класс, оксида углерода СО, углеводородов СН, оксидов азота NОx, частота вращения вала двигателя, степень положения открытия дроссельной заслонки.

1 Introduction

One of the main problems of developed countries is the problem of ecology. This problem is not a problem that each country can solve locally, but is one of the global problems. It is difficult to evaluate cars by environmental assessment methods, i.e. testing methods.

Due to narrowness of testing methodology there are control problems. Therefore, an attempt has been made to calculate the control method of a car not only by a special calculation method but also by using the data obtained from ECU.

2 Review of literature

The determination of exhaust gases by calculation methods and test methods began in 1936. In the article B. A. D'Alleva, W. G. Lovell a complete analysis of exhaust gases for carbon dioxide, carbon monoxide, hydrogen, methane and oxygen was performed using directly measured air-fuel ratios for three engines with different operating conditions and different air measuring devices[8]. Several such scientific sources have been analysed[9, 10, 11, 12].  

European countries are conducting many scientific researches in this field. In particular, Justin Bishop, Justin D.K and others have carried out works to investigate the fuel consumption in the vehicle cycle and the amount of exhaust in the vehicle per unit time[1]. The research results on the development of exhaust gas cleaning system of turbine five-stroke engine Noga, Marcin are presented. A characteristic feature of the five-stroke engine is the use of an additional expansion process to improve the overall efficiency. The problem of catalytic converter is that it has low exhaust gas temperature [2].

Hata, Hiroo et al. In this study, they measured the exhaust gases of petrol engines running after different idle periods using a dynamometer. The aftertreatment performance of a three-component catalytic converter was evaluated using chemical-kinetic modelling of chemical reactions in the catalyst combined with the time-dependent energy conservation equation [3].

A number of research works have been carried out by specialists in our country. In particular, it used special programmes to count the debris at the intersection[4] and calculated the main engine parameters in the driving cycle [5,6,7]. Compliance with the ecological class of a car has become a strict criterion for every car [16]. Our country is also a member of this standard.

Table 1.

Ecological class by year of vehicle production and country of manufacturer

Many scientific researches of specialists in the field of reduction of car exhaust gases are implemented in practice and bring results. In our country we can give an example of many researches of our scientists in this field.

3 Methodology

The purpose of our research is to take certain data from an existing ECU and try to create a calculation method.

The following parameters were obtained on a passenger car tested in the laboratory: engine crankshaft speed, throttle opening degree in 4 cases 25-50-75-100%, air-fuel ratio in the calculation of exhaust gases, we compare 3 types of CO, CH, NOx. We use the graph of exhaust gas dependence on fuel-air mixture (Fig. 1) [13]. The data in Table 2 are obtained during the tests, the values at each angular speed of the engine are obtained.

Table 2.

Engine test results of the NEXIA vehicle

The following terms are used in the study:

ECU - Electronic Control Unit; CO - carbon monoxide, %; CH - hydrocarbons, mln^-1 ; NOх – oxides of nitrogen, mln^-1 ; E Speed, rpm – engine shaft speed; T Pos, % – degree of throttle opening position, %; AFR - Air/Fuel Ratio;

Figure 1 below shows a graph of exhaust as a function of α, and the amount of exhaust at 4 different throttle positions is shown in colour. From the figure, it can be seen that mainly in the values of 25% α=0.98-1.05 and 50% α=0.94-1.01 the ECU is learning how reliable it is. A parity value of α=1 is required for reliable operation of any engine. The functional equations were constructed by approximating the graph.

Figure  1. Dependence of exhaust gases on fuel-air mixture

When calculating the air-fuel ratio, we first divided the results obtained during the experimental work by the value of 14.7, related the obtained values to the engine crankshaft speed (Fig. 2).

Figure 2. Graph of dependence of engine crankshaft speed and the value of α

Based on Table 2, a graph of the dependence of the composition of the fuel-air mixture on the engine crankshaft speed was plotted in Figure 3 below.

Figure  3. Graph of air-fuel ratio and engine crankshaft rotation speed

4 Results

 The obtained results were calculated in MatLab R2014a programme and displayed graphically. As a result, a map of waste gases was drawn up. This is one of our main results. The reason is that today's modern calculation method is to map the emissions. The graphs of Figures 4-5 below are based on Table 2, in particular, part "a" of Figure 4 is developed based on Figure 2 above. The quantities of CO, CH and NOx gases are given in Figure 1.

                       а)                                                                                      b)

Figure  4 . Dependence graphs

a - Dependence on α, alpha(α), (n) Crankshaft speed of the internal combustion engine, (th - throttle valve) position of the throttle valve; b - Dependence on CH.

а)                                                                                      b)

Figure  5. Dependence graphs. a - Dependence on NOx; b - Dependence on CO

The map was designed using the above 3D graphics (Figure 6). All these maps were calculated from the results of the vehicle standing tests. Future research aims to develop an exhaust map of the driving cycle of the vehicle.

а)

b)

с)

d)

Figure 6. Map of exhaust gas. a - to the value of α; b - to the amount of CH; c - to the amount of NOx; d - dependence on the amount of CO

NOx gas emissions were higher, with higher values at 25% and 50% throttle and lower values at 75% and 100%. The EGR system is used in modern engines to reduce the amount of NOx exhaust gas. Experiments show that re-introduction of 5 per cent of the exhaust gas reduces nitrogen oxide emissions to 40 per cent of the original level, and re-introduction of 15 per cent reduces them to 60-70 per cent[14].

5 Conclusions

The exhaust gases of a car depend on many parameters. Through this study, we have related the amount of exhaust gases to the engine crankshaft speed. As we have mentioned above, we have conducted the study without using any gas analyser. We did the analysis based on the existing graph. We used a petrol engine and performed theoretical calculations. The next stage of our research work is to continue with experiments and comparisons.

A calculation method was developed. Approximate values of R² = 0.987 for CO, R² = 0.992 for CH, R² = 0.974 for NOx were obtained (Figure 1). This can be continued again. Action cycles are also developed to realise dynamic processes.

References:

1. Bishop, Justin D.K, Stettler, Mark Ye.J, Molden, N., Boies, Adam M., (2016) Engine maps of fuel use and emissions from transient driving cycles, Applied Energy, 202-217, 183. http://dx.doi.org/10.1016/j.apenergy.2016.08.175
2. Noga, Marcin. (2019). A three-way catalyst system for a five-stroke engine. Czasopismo Techniczne. 3. 149-183. 10.4467/2353737XCT.19.039.10213.
3. Hata, Hiroo., Okada, Megumi., Yanai, Koichi., Kugata, Masahiko., Hoshi, Junya. (2022). Exhaust emissions from gasoline vehicles after parking events evaluated by chassis dynamometer experiment and chemical kinetik model of three-way catalytic converter. Science of The Total Environment, 157578, 848 http://dx.doi.org/10.1016/j.scitotenv.2022.157578 
4. Kutlimuratov, K., Khakimov, S., Mukhitdinov, A., & Samatov, R. (2021). Modelling traffic flow emissions at signalized intersection with PTV vissim. E3S Web of Conferences, 264, 02051. https://doi.org/10.1051/e3sconf/202126402051
5. Mukhitdinov, A., Abdurazzokov, U., Ziyaev, K., & Makhmudov, G. (2023). Method for assessing the vehicle energy efficiency on a driving cycle. 060028. https://doi.org/10.1063/5.0114531
6. Mukhitdinov, A., Ziyaev, K., Abdurazzokov, U., & Omarov, J. (2023). Creation of the driving cycle of the city of Tashkent by the synthesis method. 060029. https://doi.org/10.1063/5.0126363
7. Mukhitdinov, A., Ziyaev, K., Omarov, J., & Ismoilova, S. (2021). Methodology of constructing driving cycles by the synthesis. E3S Web of Conferences, 264, 01033. https://doi.org/10.1051/e3sconf/202126401033
8. B. A. D'Alleva, W. G. Lovell. Relation of Exhaust Gas Composition to Air-Fuel Ratio. SAE Transactions, Vol. 31 (1936), pp. 90-98 (9 pages) https://www.jstor.org/stable/44439093
9. R. S. Spindt. Air-Fuel Ratios from Exhaust Gas Analysis. SAE Transactions, Vol. 74, Papers 650236—650530 (1966), pp. 788-793 (6 pages) https://www.jstor.org/stable/44554371 
10. S. H. Chan, J. Zhu. Exhaust Emission Based Air-Fuel Ratio Model (I): Literature Reviews and Modelling. SAE Transactions, Vol. 105, Section 4: JOURNAL OF FUELS AND LUBRICANTS (1996), pp. 408-417 (10 pages) https://www.jstor.org/stable/44729069
11. Dermot Lynch, William J. Smith. Comparison of AFR Calculation Methods Using Gas Analysis and Mass Flow Measurement. SAE Transactions, Vol. 106, Section 4: JOURNAL OF FUELS AND LUBRICANTS (1997), pp. 311-321 (11 pages) https://www.jstor.org/stable/44731573
12. Lamont Eltinge. Fuel-Air Ratio and Distribution from Exhaust Gas Composition. SAE Transactions, Vol. 77, Section 1: Papers 680005–680246 (1968), pp. 425-450 (26 pages) https://www.jstor.org/stable/44565074
13. Двигатели внутреннего сгорания: Теория поршневых и комбинированных двигателей./ Под ред. А.С.Орлина, М.Г.Крутлова. - 4-е изд., перераб. и доп. - М.: Машиностроение. 1983. - 372 с
14. K.А.Sharipov "Fuels - Lubricants" training manual. "Mehnat". Tashkent 2001.
15. Электронный ресурс https://x-engineer.org/air-fuel-ratio
16. Электронный ресурс https://infotables.ru/avtomobili/1214-yekologicheskij-klass-avtomobilya