Estimation of Emissions Due to Two-Stroke Engines in Khartoum

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Estimation of Emissions Due to Two-Stroke Engines in Khartoum

Hunaida Abd Elbage Abazar Ahmed, Kamal Eldin Eltayeb Yassin

Chemical Engineering Department, University of Khartoum, Sudan

Abstract:- This study intended measuring the emissions of carbon monoxide and particulate matter from two-stroke engines in Khartoum. Field data were collected through interviews, questionnaire, measurements and laboratory tests. Federal Test Procedure, United Nations Economic Commission and Japanese procedures have been applied to simulate the emissions form two-stroke engines on road. The measurements were carried out by using electronic portable equipment to measure the concentrations of pollutants in an ambient air. National Ambient Air Quality Standards and Air Quality Index were applied on measured emissions to determine and compare the risk rating of two-stroke engines emissions. We found that, different sites suffered from high concentration of carbon monoxide, particulate matter of 10 and 2.5 microns in diameter due to emissions from two-stroke engines. At the peak period from 12:00 pm to 7:00 pm, the average concentration of carbon monoxide, particulate matter of 10 and 2.5 microns in diameter exceeds the maximum permissible exposure limit by 568%, 265% and 579%, respectively. It was concluded to, the using of two-stroke engines contribute to one of the environmental problems in Sudan. Therefore, it was recommended to produce bio-lubricant oils for two-stroke engines instead of petroleum-based oils. In addition, standards and regulations must be more binding and restrictive to control the emissions, misuse of lubricants and raise awareness among users of two-stroke engines in Khartoum.

Keywords: Air pollutants, Two-stroke engines, Carbon monoxide, Particulate matter, Air Quality Index.

  1. INTRODUCTION

    The exhaust of automobiles is one of the major contributors to the world's air pollution problem [1]. Two-stroke engines emit significant amounts of Carbon Monoxide (CO) Particulate matter (PM), Hydrocarbon (HC), Nitrogen Oxides (NOx) and Sulfur Dioxide (SO2) [2, 3, 4]. According to National Ambient Air Quality Standards, those pollutants are known as criteria pollutants that had serious impacts on human health and environment [5, 6]. Two-stroke engines are considered total-loss of type lubricating systems so the oil is mixed with fuel [7].

  2. METHODOLOGY

This study was arranged in two steps:

  • The first step is to study the current status of emissions from two-stroke engines due to non-availability data on pollution due to it in Khartoum.

  • The second step is to simulate the emissions from two-stroke engines on road by applying the most common international procedures, which are U.S Federal test procedure, United Nations Economic Commission for Europe and Japanese test procedure.

    1. Operational area and study location

      Khartoum state was selected to study the effect of two stroke engines on an ambient air quality because it has the largest proportion of vehicles that have a two-stroke engine in Sudan. For the accuracy purposes, the operational area was divided into sub-locations that are Khartoum, Khartoum North and Omdurman, each one contained 50 sites.

    2. Sampling and data collection

      Data Quality Objectives (DQO) was followed as EPA recommended for systematic planning of environmental data collection [8]. Field data were collected through interviews, questionnaire, measurements and laboratory investigations. The questionnaire was designed to measure the degree of air pollution perception between two-stroke engines users and precisely represented appropriate data of the environmental problem that was investigated.

      Air sampling is based on capturing the contaminant from a known volume of air, measuring the amount of contaminant captured, and expressing it as a concentration. The air is passed through a filter medium (normally a paper for solid contaminants and a sorbent for gases). The volume of air is measured against the amount of contaminant captured. This gives the concentration, which is expressed either as milligrams per cubic meter (mg/m3) or parts per million (ppm) [9].

      The sampling design was built based on judgmental sampling method and to obtain 4 samples on each sampling site at early morning, mid-day, early evening and at night.

    3. Laboratory instruments

      1. Two-stroke engines

        The auto rickshaw is 3-wheeler vehicle with a 2-sttroke engine. It is considered a common form of urban transport as a vehicle for hire and for private use in many countries around the world, especially developing countries. Bajaj Auto is the worlds largest auto rickshaw manufacturer. In Sudan, it is called Raksha and it is the most common mean of transportation.

      2. Sensitive gas analyzer; Aeroqual series 500

        The series 500 air quality sensor enables accurate real-time surveying of common outdoor air pollutants, all in an ultra- portable handheld monitor (Figure 2-1). Air quality professional typically use the series 500 for short-term air quality studies and carrying out checks on pollution hot spots. The series 500 can also be deployed for short-term fixed monitoring by adding an optional outdoor enclosure [10]. Here it was used to measure the amount of CO concentration surrounding two- stroke engines.

        Figure 2-1: Sensitive gas analyzer

      3. Particles analyzer; Aerocet 831

        The Aerocet 831 is a small, lightweight, battery operated, handheld mass profiler. This instrument simultaneously monitors PM1, PM2.5, PM4, PM10 and TSP levels. The multifunction rotary dial provides simple and efficient operation. The internal battery pack provides 8 hours of continuous operation. The Aerocet 831 stores up to 2,500 sample events, which can be viewed on the display or exported to a computer via the USB port (Figure 2-2). The lightweight instrument is only 28 ounces that it is perfect survey tool for a wide range of applications [11].

        Figure 2-2: Particles analyzer

      4. Meter and stopwatch

      5. Lubricant oil (Fuchs Titan) Table 2-1)

        Table 2-1: Titan Super GT specifications

        Properties

        Unit

        Value Test

        Commercial oil

        Method

        Flash Point

        °C

        246

        ASTM D 92

        Pour Point

        °C

        -24

        ASTM D 97

        Dynamic Viscosity @ – 15°C

        mPa.s

        8500

        ASTM D 5293

        Density @ 35 °C, 15 °C

        g/ml

        0.879

        ASTM D 4052

        Kinematic Viscosity @ 40 °C

        mm2/s

        180

        ASTM D 445

        Kinematic Viscosity @ 100 °C

        mm2/s

        19.5

        ASTM D 445

        Viscosity Index

        129

        ASTM D 2270

    4. Analytical techniques

      1. Microsoft Excel office was used for calculations

      2. National Ambient Air Quality Standards and Air Quality Index (Equation 2-1) were applied for analyzing and comparing the risk rating of two-stroke engines emissions.

        Equation 2-1: Air Quality Index Equation [12]

        AQI = (PMobsPMmin)(AQImaxAQImin) + AQImin (2-1)

        (PMmaxPMmin)

        Where;

        PMobs observed 24-hour average concentration.

        PMmax: maximum concentration of AQI color category that contain PMobs. PMmin: minimum concentration of AQI color category that contain PMobs. AQImin: maximum AQI value for color category that corresponds to PMobs. AQImin: minimum AQI value for color category that corresponds to PMobs.

        Table 2-2: Air Quality Index [12]

  1. RESULTS AND DISCUSSION

    3.1 Analysis and discussion of questionnaire

    In spite of, 77% of two-stroke engines users are either young graduates or still studying, their information is very poor in lubricants. Not only that, but they have a misconception about the amount of oil used to blend with the fuel, which is the greater the amount of oil mixed, the performance of two-stroke engines work optimized. In addition to that, poor quality oils are used as lubricant for two-stroke engines such as; four-stroke motor oils, which are not prepared for blending with fuel or combustion (Figure 3-1, Figure 3-2).

    less than 15

    15 – 25

    26 – 35

    36 – 50

    over 50

    Percentage

    0.00%

    55.56%

    44.44%

    0.00%

    0.00%

    less than 15

    15 – 25

    26 – 35

    36 – 50

    over 50

    Percentage

    0.00%

    55.56%

    44.44%

    0.00%

    0.00%

    60.00%

    50.00%

    Percentage

    Percentage

    40.00%

    30.00%

    20.00%

    10.00%

    0.00%

    range of age

    Figure 3-1: Age of two-stroke engines users

    44.44%

    33.33%

    22.22%

    0.00%

    0.00%

    Basic

    High school

    Under Graduated

    Graduated

    Post Graduated

    Series1

    0.00%

    22.22%

    33.33%

    44.44%

    0.00%

    44.44%

    33.33%

    22.22%

    0.00%

    0.00%

    Basic

    High school

    Under Graduated

    Graduated

    Post Graduated

    Series1

    0.00%

    22.22%

    33.33%

    44.44%

    0.00%

    50.00%

    45.00%

    40.00%

    Percentage

    Percentage

    35.00%

    30.00%

    25.00%

    20.00%

    15.00%

    10.00%

    5.00%

    0.00%

    The level

    Figure 3-2: Educational level of two-stroke engines users under study

    66.7% of users of two-stroke engines have awareness about the effect of contaminated drinking water and food on their lives. Moreover, most of them complained of contaminated drinking water but the authorities did not care. 50% of the sample was aware of the impact of contaminated surface water on their health but believe that: surface water treats itself from any pollution so, there is no negative impact on water quality or ecological life. Only people with respiratory or heart diseases who are concerned with air pollution and greenhouse effects (Figure 3-3).

    0.8

    0.7

    percentage

    percentage

    0.6

    0.5

    0.4

    0.3

    0.2

    0.1 0

    0

    33.30%

    66.70%

    33.30%

    50%

    66.70%

    Item Air Pollution Drinking

    water Pollution

    Green House Effect

    surfce water pollution

    polluted Food

    Environmental Problems

    Figure 3-3: The degree of awareness of two-stroke engines users towards environmental issues

      1. Results of Measurements from Field Tests

        1. On Road

          According to the sampling design, it was observed that, the concentration levels of measured pollutants in the sampled population were differed from period to period according to people activities during the day. The highest concentration levels of CO were found in the mid-day for all sampled populations, while at early morning, the concentration level of it was recorded the lowest values compared with the others in the target population. Even that they were still extremely exceeded the maximum permissible exposure limits (PEL) at different periods during the day (Figure 3-4, Figure 3-5 and Figure 3-6).

          100

          CONC. IN PPM

          CONC. IN PPM

          80

          60

          40

          20

          0

          1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

          No. of Station

          Omdurman E. morning Omdurman Mid day Omdurman E.evening Omdurman Mid night

          Figure 3-4: Carbon monoxide level of sampled population according to the sampling design in Omdurman

          In addition to that, PM10 and PM2.5 were followed the same carbon monoxide track in their fluctuations during daytime (Figure

          3-8 and Figure 3-9).

          100

          CONC. IN PPM

          CONC. IN PPM

          80

          60

          40

          20

          0

          1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

          No. of Station

          Kh. North E. morning Kh. North Mid day Kh. North E.evening Kh. North Mid night

          Figure 3-5: Carbon monoxide level of sampled population according to the sampling design in Khartoum north

          It was concluded that, there was a direct relationship between the people activities during the day and the amount of emissions in an ambient air.

          100

          CONC. IN PPM

          CONC. IN PPM

          80

          60

          40

          20

          0

          1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

          No. of Station

          Khartoum E. morning Khartoum Mid day Khartoum E.evening Khartoum Mid night

          Figure 3-6: Carbon monoxide level of sampled population according to the sampling design in Khartoum

              • Air quality index calculation

Air quality index (AQI) was calculated to demonstrate the health effects of emissions on people in the target population. To calculate AQI, an average concentration level of CO, PM10 and PM2.5 at different locations were obtained and shown in Figure 3-7, Figure 3-8 and Figure 3-9 respectively. The observed average concentration of pollutants were applied in Equation 2-1) to get AQI for the target population according to the sampling design (Table 3-1).

69.534

69.534

67.032

67.032

65.0836

65.0836

80

53.304

53.304

49.1758

49.1758

56.686

56.686

70

45.408

45.408

45.6362

45.6362

46.522

46.522

60

Conc. in PPM

Conc. in PPM

50

19.4364

19.4364

40

19.058

19.058

18.988

18.988

30

20

9

9

9

9

9

9

9

9

10

0

E. morning Mid day E.evening Mid night

The periods

Max.PEL Omdurman Kh. North Khartoum

Figure 3-7: Average concentration of CO according to the sampling design for the target population

700

600

Conc. in µg/m³

Conc. in µg/m³

500

400

300

207 174

258

586 593

638

534

476 456

329

248

200

100

0

150 150 150 150

E. morning Mid day E.evening Mid night The periods

156

Max.PEL Omdurman Kh. North Khartoum

Figure 3-8: Average concentration of PM10 according to the sampling design for the target population

It was found that, during the day except in the early morning, the target population is suffered from high contamination of CO. This degree of CO concentration causes serious aggravation of cardiovascular symptoms such as chest pain, in people with cardiovascular disease and impairment of strenuous activities in general population. Although, the concentration of CO in the early morning was lower than the rest of the day, the ambient air was found to be very unhealthy for people had been suffering from respiratory or heart diseases, the elderly and children. Therefore, people with cardiovascular disease such as angina should avoid exertion and everyone else should limit heavy exertion.

140

120

Conc. in µg/m³

Conc. in µg/m³

100

80

60

40

27 29 24

126

103

88

67

53 52

39 42

33

20 12 12 12 12

0

E. morning Mid day E.evening Mid night

The periods

Max.PEL Omdurman Kh. North Khartoum

Figure 3-9: Average concentration of PM2.5 according to the sampling design for the target population

Table 3-1: AQI of average CO, PM10 and PM2.5 concentration of the sampled population

The pollutants

Location

AQI

Early morning

Mid-day

Early evening

Mid night

CO

Omdurman

224

>500

>500

450

Khartoum north

218

>500

487

452

Khartoum

227

>500

>500

451

PM10

Omdurman

127

482

430

188

Khartoum north

110

489

365

147

Khartoum

152

>500

340

101

PM2.5

Omdurman

82

168

144

110

Khartoum north

87

176

157

117

Khartoum

76

187

142

95

In the mid-day and early evening of the day, the samples that were absorbed through the filter showed a high concentration of PM10. That hazardous level is very dangerous for the symptoms of respiratory system and worsening the lung diseases. Therefore, everyone in the target population should any outdoor exertion and people with respiratory diseases should remain indoor.

The effect of PM10 contamination on ambient air in the early morning and mid-night was similar to PM 2.5 in the middle of night and in the early evening. It was unhealthy for people with respiratory or heart disease, the elderly and children because it increases the likelihood of respiratory symptoms, aggravation of the lung disease and premature mortality in persons with cardiopulmonary disease.

In the mid-day, the concentration of PM 2.5 in the air was found to be unhealthy, leading to the aggravation of heart or lung disease and premature mortality in people with cardiopulmonary disease and the elderly. In addition, the respiratory effects of the target population may be eroded, so everyone should reduce the prolonged effort.

The lowest level of PM2.5 contamination in the target population was measured in the early morning, which is considered relatively safe for people, but they have to be careful to maintain their health.

      1. On laboratory

        80

        70

        60

        50

        40

        30

        20

        10

        0

        80

        70

        60

        50

        40

        30

        20

        10

        0

        CO Emissions at 0m (ppm)

        CO Emissions at 0m (ppm)

        CO Emissions at 2m (ppm)

        Max.PEL of CO

        1

        CO Emissions at 2m (ppm)

        Max.PEL of CO

        1

        Emission in ppm

        Emission in ppm

        1. FTP (US) procedure

          1 = 200 sec

          1 = 200 sec

          2

          2

          3

          3

          4

          4

          5

          5

          6

          6

          7

          Time (s)

          7

          Time (s)

          8

          8

          9

          9

          10 11 12 13

          10 11 12 13

          Figure 3-10: FTP (US) procedure for CO emissions from two-stroke engine under test at different distance from exhaust pipe, zero concentration at stopped time.

          In Figure 3-10; it was observed that the amount of CO concentration start at the highest level and decreased over a time when the speed of engine was decreased until the engine eventually was turned off. The measurements at a distance of 2 meters was done after the measurement at a distance of zero meter had been taken, so it was noted that the area was saturated with concentration of CO more over NAAQS for carbon monoxide concentration level in an ambient air, which it is very dangerous, and harmfully to human health and environment.

        2. European procedure

          European driving cycle is simple and consisting of stable speeds. Although this procedure is considered the ideal position in the simulation of emissions, the concentration of CO level from two-stroke engines as result of using the commercial lubricant oils was very harmful and serious effects (Table 3-2).

          Table 3-2: CO emissions based on European procedure from two-stroke engines because of using the commercial lubricant oil

          Reading

          Emissions of CO using a commercial lubricant oil (ppm)

          CO Emissions at 0m (ppm)

          73.74

          CO Emissions at 2m (ppm)

          50.52

        3. Japanese procedure

          In this procedure, it was observed that the amount of CO emissions was very high at the start of the experiment (Table 3-3); this was due to the nature of this procedure cycles that are allowed the engines to warm up at a high speed.

          Table 3-3: CO emissions based on Japanese procedure from two-stroke engines because of using the commercial lubricant oils

          CO Emissions at 0m (ppm)

          CO Emissions at 2m (ppm)

          10-mode

          1st segment

          77.82

          54.47

          2nd segment

          43.56

          39.43

          3rd segment

          26.81

          25.18

          15-mode segment

          24.49

          22.68

        4. Air quality index

          The average concentration of PM10 and PM2.5 was shown in Figure 3-11 and Figure 3-12. AQI was calculated using Equation 2-1 and displayed in Table 3-4.

          700

          Conc. in µg/m³

          Conc. in µg/m³

          600

          500

          400

          300

          200

          100

          0

          590

          530

          450

          150

          US

          Japanese European Max PEL

          US Japanese European Max PEL

          Test procedure

          Figure 3-11: The average concentration of PM10 emissions from two-stroke engines by applying international procedures in the laboratory

          250

          Conc. in µg/m³

          Conc. in µg/m³

          200

          150

          100

          50

          0

          200

          160

          110

          12

          US

          Japanese European Max PEL

          US Japanese European Max PEL

          Test procedure

          Figure 3-12: The average concentration of PM2.5 emissions from two-stroke engines by applying international procedures in the laboratory

          For the different applicable procedures, the concentration of PM10 in ambient air was found to be hazardous and was consistent with the results obtained from road measurements (Table 3-1). In addition, the concentration of PM2.5 in ambient air through the application of US and Japanese procedures was consistent with results obtained from road measurements, while the results obtained from the European procedure, were contrary to reality because they assume the ideal movement in emulating emissions.

          Procedure

          US

          489

          250

          Japanese

          426

          210

          European

          332

          179

          Procedure

          US

          489

          250

          Japanese

          426

          210

          European

          332

          179

          Table 3-4: AQI for the emissions of particulate matter from two-stroke engines through the application of international procedures

          PM10

          AQI

          PM2.5

  1. CONCULUSION

    The users of two-stroke engines in Khartoum use inappropriate quantity of lubricant oil due to their lack of knowledge about the correct amount to be used and their perception that more lubricant will provide greater protection against piston seizure. The problem is further enhanced because they tend to use excessive oil of poor quality because it is economically feasible.

    All of that and else contribute to environmental problems in Sudan due to two-stroke engines using. The amount of pollutants are emitted by those engines exceeds the safety levels indicated by National Ambient Air Quality Standards (NAAQS) and World

    Health Organization (WHO). Therefore, lubricant oils that were being used for two-stroke engines in Sudan it was inappropriate for the environment and human health and should be replaced by eco-friendly lubricants.

  2. ACKNOWLEDGEMENT

    We would like to acknowledge grant-funding support by Dr. Elfadil Elmelik in memory of the late son Eng. Elfatih. We are indebted to semi-final chemical engineering students who helped us in laboratory tests.

  3. REFERENCES

[1]

W. W. Pulkrabek, Engineering Fundamentals of the Internal Combustion Engine, 1st ed., platteville: University of Wisconsin, 2009, pp. 5, 30.

[2]

J. B. Heywood, Internal Combustion Engine Fundamentals, vol. II, Massachusetts: Massachusetts Institute ofTechnology, Apr.2001, pp. 567-572.

[3]

J McDonald, "Evaluation of Emissions from Asian 2-stroke Motorcycles," Society of Automotive Engineers, 2005.

[4]

Technical Bulletin 5, "Exhaust Emissions of Toxic Air Pollutants using Reformulated Gasolines," Auto/oil coordinating Research Council Inc, Georgia, 2010.

[5]

R. A. Buchholz, "National Ambient Air Quality Standards," Britannica, 26 May 2017. [Online]. Available: http://www.Britannica.com. [Accessed 30 April 2018].

[6]

W. Kindzierski, P. Chelme-Ayala and E.-D. M. Gamal, "Ambient Air Quality Data Summary and Trend Analysis," Wood Buffalo Environmental Association, Alberta, 2009.

[7]

AMSOIL, "Two-cycle Engine Applications and Lubrication Needs," AMSOIL Action News, July 2001.

[8]

EPA, "Guidance on Choosing a Sampling Design for Environmental Data Collection," Office of Environmental Protection Information, Washington, 2002.

[9]

SKC, "An Introduction to Air Sampling," July 2015. [Online]. Available: www.skcltd.com. [Accessed 14 June 2017].

[10]

S. J. Vuetilovoni, "Portable Monitors User Guide," Aeroqual limited, Auckland, 2017.

[11]

J. Elseth, "AEROCET 831 manual," Met One Instruments, Inc, Oregon, 2014.

[12]

E. Salvador, "Air Quality Index," San Salvador, 2012.

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