- Email: [email protected]
Effect of comprex supercharging on diesel emissions
Energy Conversion and Management 44 (2003) 1745–1753 www.elsevier.com/locate/enconman
Effect of comprex supercharging on diesel emissions Yakup I_ ßc_ıng€ ur b
a,*
, Can Hasß_ımo glu b, M. Sahir Salman
a
a Faculty of Technical Education, Gazi University, Teknik Okullar, 06503 Ankara, Turkey Faculty of Technical Education, Selcßuk University, Alaeddin Kampus€ u, 42031 Konya, Turkey
Received 18 May 2002; accepted 2 September 2002
Abstract Diesel engine emissions are highly complex mixtures. They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. Particulates and NOx emissions are the important components of the Diesel exhaust. The composition of Diesel exhaust varies considerably, depending on engine type, operating conditions, fuel, and lubricating oil. In this research, the effects of supercharging, which is one of the engine operational parameters, on Diesel emissions have been investigated. For this purpose, a comprex, CX (pressure wave supercharger) was designed and manufactured and then matched to an indirect injection Diesel engine. During the engine tests, the emission parameters (CO, SOx , NOx and smoke density) have been observed and measured for different pulley ratios at full load conditions. The results showed that CX supercharging may be an alternative way of NOx reduction with some modifications. 2002 Elsevier Science Ltd. All rights reserved. Keywords: Supercharging; Pressure wave machine; Exhaust emission; Diesel engine
1. Introduction Motor vehicles are the major source of air pollution in most urban areas. Today, atmospheric pollution from Diesel exhaust is getting ever worse, particularly in large city areas. Diesel engines have a high thermal efficiency, and from an economic point of view, they also offer the advantage of efficient fuel combustion. However, compared with a gasoline engine, a Diesel engine emits
*
Corresponding author. Tel.: +90-312-2126820/1851; fax: +90-312-2120059. ur). E-mail address: [email protected] (Y. I_ ßc_ıng€
0196-8904/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 6 - 8 9 0 4 ( 0 2 ) 0 0 2 2 0 - 0
1746
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
2–20 times more nitrogen oxides (NOx ) and 30–100 times more particulate matter also referred to as soot or smoke [1,2]. Diesel engine emissions are highly complex mixtures. They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. These emissions are a public health concern because the emitted particulates are small (<2.5 lm) and easily respirable, the particulates contain hundreds of chemicals, some being known carcinogens and mutagens. The emitted gaseous particles contain many irritants and toxic chemicals. Oxides of nitrogen (NOx ), which are ozone precursors, are among the combustion products in the gaseous phase. Ozone is known as a lung irritant, which can cause respiratory problems among the young and old, especially asthmatics [3–6]. The composition of Diesel exhaust varies considerably, depending on engine type, operating conditions, fuel, lubricating oil and whether an emission control system is present. Three basic approaches are commonly used to reduce Diesel emissions: • Design parameters, cylinder head and combustion chamber design, number of valves, bore to stroke ratio, compression ratio, inlet and exhaust port shape etc. • Operational parameters, engine management, mixture formation and control, supercharging, valve timing, internal and external exhaust gas recirculation (EGR) etc. • Exhaust gas after treatment, catalytic converter systems, secondary air injection, thermal reactors, particulate traps etc. [3,7]. In this research, the effect of supercharging on Diesel emissions has been investigated. For this purpose, a comprex, CX (pressure wave supercharger) was designed and manufactured, and then matched to an indirect injection diesel engine. During the engine tests, the emission parameters (CO, SOx , NOx and smoke density) have been observed for different pulley ratios (PR) at full load conditions.
2. Comprex supercharging The term supercharging refers to increasing the air (or mixture) density by increasing its pressure prior to entering the engine cylinder. Three basic methods are used to accomplish this. • Mechanical supercharging, where a separate pump, blower or compressor, usually driven by power taken from the engine, provides the compressed air. • Turbocharging, where a turbocharger, TC (a compressor and turbine on a single shaft) is used to boost the inlet air (or mixture) density. Energy available in the engineÕs exhaust stream is used to drive the TC turbine, which drives the TC compressor that raises the inlet air flow rate fluid density prior to entry to the engine cylinder. • Pressure wave supercharging uses the wave action in the intake and exhaust systems to compress the intake mixture. An example of a pressure wave supercharging device is the CX, which uses the pressure available in the exhaust gas stream by direct contact of the fluids in narrow flow channels [8].
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
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Pressure wave superchargers (CX) make use of the fact that if two fluids having different pressures are brought into direct contact in long narrow channels, equalization of pressure occurs faster than mixing. A schematic view of a CX is shown in Fig. 1. The CX is a very efficient device because energy exchange occurs across pressure waves that travel at the speed of sound. It is composed of two concentric cylinders between which radial straight planes are arranged, giving rise to long channels of constant cross section. When applied to an internal combustion engine as a supercharger, the wave rotor is first filled with fresh air. Hot gases coming out of the combustion chamber enter the rotor and compress this air (being in contact with it), which is in the following directed towards the combustion chamber. Then, hot gases are expanded through the exhaust pipe to the atmosphere. At each end of the rotor there are lateral non-rotating flanges (stators). These are perforated, which gives inlet and outlet ports directing the air and the gases inside and outside the rotor via ducting systems [9,10]. The CX is distinguished by the following principal features: • The energy exchange is performed by pressure waves. This process is practically instantaneous, and it offers the option of a controlled mixing of gas and air. • The throughput characteristic of the machine is better adapted to that of the piston engine than the TC, as illustrated by Fig. 2. The natural characteristics of the pressure wave machine, thus, correspond substantially to those of a regulated turbine. The standard CX shows a more
Fig. 1. Schematic view of a comprex [9]. (1) Fresh air, (2) compressed air, (3) hot gases, (4) hot gases and air towards the exhaust pipe.
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
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Fig. 2. The representation of the virtual nozzle area of the supercharger along the full load line [12].
favorable characteristic in comparison to the TC. The CX characteristic is further improved by a mechanism to control the flow into the gas pocket. • The CX is not constrained by a surge limit. Its operating map is wide ranging. • Simple control mechanisms are adequate to improve its attributes further [11].
3. Experimental The experiments were performed in a four cycle indirect injection Diesel engine. The specifications of the test engine are given in Table 1. A CX was used to supercharge the engine. The rotor channels of the CX were designed according to the maximum fluid flow of the engine. Then, the CX was matched to the Diesel engine. A Go-Power Dt 100 hydraulic dynamometer was used to load the engine. Air consumption was measured with a FCO-10 digital flow meter. To determine the exhaust emission values, a Gaco-Sn gas analyzer was used. The schematic layout of the test system is shown in Fig. 3. Before the tests, the engine was tuned, and the engine oil was changed. The tests started after reaching the normal working temperature of the engine. The engine was run at full load, and the speed was changed from 1500 to 4000 min1 with an interval of 500 min1 . The fuel injection pump regulator was not employed during the tests. Table 1 The specifications of the test engine Type Number of cylinders Cylinder volume Compression ratio Max. speed Max. moment Type of cooling Idle speed
XLD 418 Ford Diesel 4 1.7 l 21.5/1 44 kW @ 4500 min1 110 Nm @ 2500 min1 Water 850 50 min1
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Fig. 3. The schematic layout of test system.
Firstly, the engine was run without the CX to determine the base emission characteristics. Then, the engine was run for different PR (2.0/1, 1.75/1, 1.5/1) of the CX. To run the engine with different PR, a variable speed AC motor was used. So, the CX speed was not affected by the engine speed. To obtain a constant charge pressure, a stabilizer was connected to the compressed air output of the CX. Because of the CX operating features, manufacturing problems about precision and use of inappropriate PR, some exhaust gases can mix with the fresh air of the engine. This provides an external EGR. The EGR ratio was determined as follows [13]: %EGR ¼ 1
%O2ðCXÞ %O2ðreferenceÞ
100
ð1Þ
4. Experimental results and discussion The engine test results are shown in Figs. 4–9. Fig. 4 shows the variations of EGR ratio by engine speed. For PR 1.5/1, 1.75/1 and 2.0/1, the measured average EGR ratios are 32%, 27% and 29%, respectively. The pressure values are the static pressure values (Fig. 5). In the charge pressure axis, zero refers to atmospheric pressure. For naturally aspirated (NA) operation, the charge pressure decreases as the engine speed increases. Normally, for all PR, the charge pressure increases with engine speed when supercharging is applied. In NA operation, the CO emission is lower for all engine speeds (Fig. 6), but the CO emission increases with supercharging. This may be caused by the external EGR. The inert exhaust gases dilute the charge, so the combustion process is deteriorated.
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Fig. 4. The variations of EGR ratio for different PR by engine speed.
Fig. 5. The variations of charge pressure by engine speed for different PR.
Fig. 6. The variations of carbon monoxide (CO) emission by engine speed for different PR.
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
Fig. 7. The variations of sulphur oxide (SOx ) emission by engine speed for different PR.
Fig. 8. The variations of nitrogen oxide (NOx ) emission for different PR by engine speed.
Fig. 9. The variations of smoke density (%) for different PR by engine speed.
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As seen in Fig. 7, the SOx emission is low for all engine speeds in NA operation. As for CX operation, the SOx emission is high, particularly at low engine speeds. The levels of SOx emissions depend on the sulphur content of the fuel and lubricating oil and the operating condition of the engine [7,8,13]. As the combustion process deteriorated at low engine speed, the SOx emissions increased. By improving the combustion process, the SOx emissions would decrease. The NOx emission is higher for all engine speeds in natural aspirated operation (Fig. 8). When supercharging is applied, it is seen that the NOx reduction is proportional with the EGR ratio (Fig. 4). This means that more EGR results in lower NOx emissions. Since the recirculated exhaust gases dilute the mixture, some of the oxygen is replaced with CO2 . This will reduce the peak gas temperature and, therefore, NOx formation rates. Also, the heat capacity of the exhaust gases is higher than that of air. The exhaust gases would absorb a portion of the heat that is released during combustion. At low engine speeds, smoke emission is low in NA operation, but at high engine speeds, smoke emission is low with CX operation (Fig. 9). This is probably caused by the volumetric efficiency and temperature drop by EGR. At low speeds, the pressure losses are low in NA operation, so the volumetric efficiency would be better. This increases the local oxygen concentration in the cylinder. So, the smoke emission will be better in NA operation. The reduction of in-cylinder peak temperature by EGR prevents complete oxidation of the fuel, so the smoke emission would deteriorate for CX operation. At high engine speeds, supercharging would eliminate these effects, and smoke emission will decrease. 5. Conclusions and recommendations In this study, a CX, which is an alternative supercharger, is designed, manufactured and matched to an indirect injection Diesel engine, and then, its effects on the Diesel emissions were observed during engine tests. The engine tests showed that (i) NOx emission is reduced for all engine speeds via CX supercharging, but smoke emission is deteriorated at low and medium engine speeds. (ii) CO and SOx emissions are both higher than those of NA operation. (iii) CX supercharging may be an alternative way of reducing NOx emission, but the EGR ratio must be controlled more precisely. (iv) The experiments can be performed for different PR. (v) High technology and material should be used to manufacture the CX system. (vi) It is necessary to make an optimization between NOx and smoke emission.
References [1] Watanabe S, Kinoshita K, Hayashi N, Ohashi A, Uchida Y, Dykes D, Touchard G. An experiment to purify diesel exhaust gas using an electric trap and three types of catalysers. J Electrostatics 1997;40–41. [2] Edgar BL. Dimethyl ether and other oxygenated fuels for low emission diesel engine combustion, PhD Thesis, Mechanical Engineering, University of California, Berkeley, 1997.
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
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[3] Ouenou GS, Ouladsine M, Rachid A. Measurement and prediction of diesel engine exhaust emissions. ISA Trans 1998;37. [4] Matias FAA, de Oliveira WA, Moschim E. Fibre optic sensor for diesel engine smoke measurement. Sens Actuators, B 1997;41. [5] Health Effects Institute. Diesel exhaust: a critical analysis of emissions, exposure and health effects, April, 1995. HEI Special Report. [6] Glassmann I. Combustion. second ed. New York: Academic Press; 1986. [7] Schafer F, van Basshuysen R. Reduced emissions and fuel consumption in automotive engines. Germany: Springer Verlag/Wien; 1995. [8] Heywood JB. Internal combustion engine fundamentals. New York: McGraw-Hill Co; 1988. [9] Fatsis A, Lafond A, Ribaud Y. Preliminary analysis of the flow inside a three-port wave rotor by means of a numerical model. Aerospace and Technology 1998;(5). [10] Zhang HS, So RMC. Calculation of the material interface in a pressure wave supercharger. Proc Inst Mech Eng 1990; 204(A3). [11] Mayer A, Pauli E, Gygax J. Comprex supercharging and emissions reduction in vehicular diesel engines, SAE Paper 900881, 1990. [12] Jenny E, Hansel J, Mayer A. The transient behaviour of supercharged passenger car diesel engines fitted with particulate traps, SAE Paper 890171, 1989. [13] I_ ßcing€ ur, Y., Dizel Motorlarının Asßırı Doldurulmasında Kullanılan Bir Basıncß Dalga Makinesinin Tasarımı ve € niversitesi Fen Bilimleri Enstit€ Kullanılabilirliginin Deneysel Analizi, Doktora Tezi, Gazi U us€ u, Ankara, 1996.
Effect of comprex supercharging on diesel emissions Yakup I_ ßc_ıng€ ur b
a,*
, Can Hasß_ımo glu b, M. Sahir Salman
a
a Faculty of Technical Education, Gazi University, Teknik Okullar, 06503 Ankara, Turkey Faculty of Technical Education, Selcßuk University, Alaeddin Kampus€ u, 42031 Konya, Turkey
Received 18 May 2002; accepted 2 September 2002
Abstract Diesel engine emissions are highly complex mixtures. They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. Particulates and NOx emissions are the important components of the Diesel exhaust. The composition of Diesel exhaust varies considerably, depending on engine type, operating conditions, fuel, and lubricating oil. In this research, the effects of supercharging, which is one of the engine operational parameters, on Diesel emissions have been investigated. For this purpose, a comprex, CX (pressure wave supercharger) was designed and manufactured and then matched to an indirect injection Diesel engine. During the engine tests, the emission parameters (CO, SOx , NOx and smoke density) have been observed and measured for different pulley ratios at full load conditions. The results showed that CX supercharging may be an alternative way of NOx reduction with some modifications. 2002 Elsevier Science Ltd. All rights reserved. Keywords: Supercharging; Pressure wave machine; Exhaust emission; Diesel engine
1. Introduction Motor vehicles are the major source of air pollution in most urban areas. Today, atmospheric pollution from Diesel exhaust is getting ever worse, particularly in large city areas. Diesel engines have a high thermal efficiency, and from an economic point of view, they also offer the advantage of efficient fuel combustion. However, compared with a gasoline engine, a Diesel engine emits
*
Corresponding author. Tel.: +90-312-2126820/1851; fax: +90-312-2120059. ur). E-mail address: [email protected] (Y. I_ ßc_ıng€
0196-8904/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 1 9 6 - 8 9 0 4 ( 0 2 ) 0 0 2 2 0 - 0
1746
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
2–20 times more nitrogen oxides (NOx ) and 30–100 times more particulate matter also referred to as soot or smoke [1,2]. Diesel engine emissions are highly complex mixtures. They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. These emissions are a public health concern because the emitted particulates are small (<2.5 lm) and easily respirable, the particulates contain hundreds of chemicals, some being known carcinogens and mutagens. The emitted gaseous particles contain many irritants and toxic chemicals. Oxides of nitrogen (NOx ), which are ozone precursors, are among the combustion products in the gaseous phase. Ozone is known as a lung irritant, which can cause respiratory problems among the young and old, especially asthmatics [3–6]. The composition of Diesel exhaust varies considerably, depending on engine type, operating conditions, fuel, lubricating oil and whether an emission control system is present. Three basic approaches are commonly used to reduce Diesel emissions: • Design parameters, cylinder head and combustion chamber design, number of valves, bore to stroke ratio, compression ratio, inlet and exhaust port shape etc. • Operational parameters, engine management, mixture formation and control, supercharging, valve timing, internal and external exhaust gas recirculation (EGR) etc. • Exhaust gas after treatment, catalytic converter systems, secondary air injection, thermal reactors, particulate traps etc. [3,7]. In this research, the effect of supercharging on Diesel emissions has been investigated. For this purpose, a comprex, CX (pressure wave supercharger) was designed and manufactured, and then matched to an indirect injection diesel engine. During the engine tests, the emission parameters (CO, SOx , NOx and smoke density) have been observed for different pulley ratios (PR) at full load conditions.
2. Comprex supercharging The term supercharging refers to increasing the air (or mixture) density by increasing its pressure prior to entering the engine cylinder. Three basic methods are used to accomplish this. • Mechanical supercharging, where a separate pump, blower or compressor, usually driven by power taken from the engine, provides the compressed air. • Turbocharging, where a turbocharger, TC (a compressor and turbine on a single shaft) is used to boost the inlet air (or mixture) density. Energy available in the engineÕs exhaust stream is used to drive the TC turbine, which drives the TC compressor that raises the inlet air flow rate fluid density prior to entry to the engine cylinder. • Pressure wave supercharging uses the wave action in the intake and exhaust systems to compress the intake mixture. An example of a pressure wave supercharging device is the CX, which uses the pressure available in the exhaust gas stream by direct contact of the fluids in narrow flow channels [8].
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
1747
Pressure wave superchargers (CX) make use of the fact that if two fluids having different pressures are brought into direct contact in long narrow channels, equalization of pressure occurs faster than mixing. A schematic view of a CX is shown in Fig. 1. The CX is a very efficient device because energy exchange occurs across pressure waves that travel at the speed of sound. It is composed of two concentric cylinders between which radial straight planes are arranged, giving rise to long channels of constant cross section. When applied to an internal combustion engine as a supercharger, the wave rotor is first filled with fresh air. Hot gases coming out of the combustion chamber enter the rotor and compress this air (being in contact with it), which is in the following directed towards the combustion chamber. Then, hot gases are expanded through the exhaust pipe to the atmosphere. At each end of the rotor there are lateral non-rotating flanges (stators). These are perforated, which gives inlet and outlet ports directing the air and the gases inside and outside the rotor via ducting systems [9,10]. The CX is distinguished by the following principal features: • The energy exchange is performed by pressure waves. This process is practically instantaneous, and it offers the option of a controlled mixing of gas and air. • The throughput characteristic of the machine is better adapted to that of the piston engine than the TC, as illustrated by Fig. 2. The natural characteristics of the pressure wave machine, thus, correspond substantially to those of a regulated turbine. The standard CX shows a more
Fig. 1. Schematic view of a comprex [9]. (1) Fresh air, (2) compressed air, (3) hot gases, (4) hot gases and air towards the exhaust pipe.
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
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Fig. 2. The representation of the virtual nozzle area of the supercharger along the full load line [12].
favorable characteristic in comparison to the TC. The CX characteristic is further improved by a mechanism to control the flow into the gas pocket. • The CX is not constrained by a surge limit. Its operating map is wide ranging. • Simple control mechanisms are adequate to improve its attributes further [11].
3. Experimental The experiments were performed in a four cycle indirect injection Diesel engine. The specifications of the test engine are given in Table 1. A CX was used to supercharge the engine. The rotor channels of the CX were designed according to the maximum fluid flow of the engine. Then, the CX was matched to the Diesel engine. A Go-Power Dt 100 hydraulic dynamometer was used to load the engine. Air consumption was measured with a FCO-10 digital flow meter. To determine the exhaust emission values, a Gaco-Sn gas analyzer was used. The schematic layout of the test system is shown in Fig. 3. Before the tests, the engine was tuned, and the engine oil was changed. The tests started after reaching the normal working temperature of the engine. The engine was run at full load, and the speed was changed from 1500 to 4000 min1 with an interval of 500 min1 . The fuel injection pump regulator was not employed during the tests. Table 1 The specifications of the test engine Type Number of cylinders Cylinder volume Compression ratio Max. speed Max. moment Type of cooling Idle speed
XLD 418 Ford Diesel 4 1.7 l 21.5/1 44 kW @ 4500 min1 110 Nm @ 2500 min1 Water 850 50 min1
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
1749
Fig. 3. The schematic layout of test system.
Firstly, the engine was run without the CX to determine the base emission characteristics. Then, the engine was run for different PR (2.0/1, 1.75/1, 1.5/1) of the CX. To run the engine with different PR, a variable speed AC motor was used. So, the CX speed was not affected by the engine speed. To obtain a constant charge pressure, a stabilizer was connected to the compressed air output of the CX. Because of the CX operating features, manufacturing problems about precision and use of inappropriate PR, some exhaust gases can mix with the fresh air of the engine. This provides an external EGR. The EGR ratio was determined as follows [13]: %EGR ¼ 1
%O2ðCXÞ %O2ðreferenceÞ
100
ð1Þ
4. Experimental results and discussion The engine test results are shown in Figs. 4–9. Fig. 4 shows the variations of EGR ratio by engine speed. For PR 1.5/1, 1.75/1 and 2.0/1, the measured average EGR ratios are 32%, 27% and 29%, respectively. The pressure values are the static pressure values (Fig. 5). In the charge pressure axis, zero refers to atmospheric pressure. For naturally aspirated (NA) operation, the charge pressure decreases as the engine speed increases. Normally, for all PR, the charge pressure increases with engine speed when supercharging is applied. In NA operation, the CO emission is lower for all engine speeds (Fig. 6), but the CO emission increases with supercharging. This may be caused by the external EGR. The inert exhaust gases dilute the charge, so the combustion process is deteriorated.
1750
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Fig. 4. The variations of EGR ratio for different PR by engine speed.
Fig. 5. The variations of charge pressure by engine speed for different PR.
Fig. 6. The variations of carbon monoxide (CO) emission by engine speed for different PR.
Y. I_ ßc_ıng€ur et al. / Energy Conversion and Management 44 (2003) 1745–1753
Fig. 7. The variations of sulphur oxide (SOx ) emission by engine speed for different PR.
Fig. 8. The variations of nitrogen oxide (NOx ) emission for different PR by engine speed.
Fig. 9. The variations of smoke density (%) for different PR by engine speed.
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As seen in Fig. 7, the SOx emission is low for all engine speeds in NA operation. As for CX operation, the SOx emission is high, particularly at low engine speeds. The levels of SOx emissions depend on the sulphur content of the fuel and lubricating oil and the operating condition of the engine [7,8,13]. As the combustion process deteriorated at low engine speed, the SOx emissions increased. By improving the combustion process, the SOx emissions would decrease. The NOx emission is higher for all engine speeds in natural aspirated operation (Fig. 8). When supercharging is applied, it is seen that the NOx reduction is proportional with the EGR ratio (Fig. 4). This means that more EGR results in lower NOx emissions. Since the recirculated exhaust gases dilute the mixture, some of the oxygen is replaced with CO2 . This will reduce the peak gas temperature and, therefore, NOx formation rates. Also, the heat capacity of the exhaust gases is higher than that of air. The exhaust gases would absorb a portion of the heat that is released during combustion. At low engine speeds, smoke emission is low in NA operation, but at high engine speeds, smoke emission is low with CX operation (Fig. 9). This is probably caused by the volumetric efficiency and temperature drop by EGR. At low speeds, the pressure losses are low in NA operation, so the volumetric efficiency would be better. This increases the local oxygen concentration in the cylinder. So, the smoke emission will be better in NA operation. The reduction of in-cylinder peak temperature by EGR prevents complete oxidation of the fuel, so the smoke emission would deteriorate for CX operation. At high engine speeds, supercharging would eliminate these effects, and smoke emission will decrease. 5. Conclusions and recommendations In this study, a CX, which is an alternative supercharger, is designed, manufactured and matched to an indirect injection Diesel engine, and then, its effects on the Diesel emissions were observed during engine tests. The engine tests showed that (i) NOx emission is reduced for all engine speeds via CX supercharging, but smoke emission is deteriorated at low and medium engine speeds. (ii) CO and SOx emissions are both higher than those of NA operation. (iii) CX supercharging may be an alternative way of reducing NOx emission, but the EGR ratio must be controlled more precisely. (iv) The experiments can be performed for different PR. (v) High technology and material should be used to manufacture the CX system. (vi) It is necessary to make an optimization between NOx and smoke emission.
References [1] Watanabe S, Kinoshita K, Hayashi N, Ohashi A, Uchida Y, Dykes D, Touchard G. An experiment to purify diesel exhaust gas using an electric trap and three types of catalysers. J Electrostatics 1997;40–41. [2] Edgar BL. Dimethyl ether and other oxygenated fuels for low emission diesel engine combustion, PhD Thesis, Mechanical Engineering, University of California, Berkeley, 1997.
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[3] Ouenou GS, Ouladsine M, Rachid A. Measurement and prediction of diesel engine exhaust emissions. ISA Trans 1998;37. [4] Matias FAA, de Oliveira WA, Moschim E. Fibre optic sensor for diesel engine smoke measurement. Sens Actuators, B 1997;41. [5] Health Effects Institute. Diesel exhaust: a critical analysis of emissions, exposure and health effects, April, 1995. HEI Special Report. [6] Glassmann I. Combustion. second ed. New York: Academic Press; 1986. [7] Schafer F, van Basshuysen R. Reduced emissions and fuel consumption in automotive engines. Germany: Springer Verlag/Wien; 1995. [8] Heywood JB. Internal combustion engine fundamentals. New York: McGraw-Hill Co; 1988. [9] Fatsis A, Lafond A, Ribaud Y. Preliminary analysis of the flow inside a three-port wave rotor by means of a numerical model. Aerospace and Technology 1998;(5). [10] Zhang HS, So RMC. Calculation of the material interface in a pressure wave supercharger. Proc Inst Mech Eng 1990; 204(A3). [11] Mayer A, Pauli E, Gygax J. Comprex supercharging and emissions reduction in vehicular diesel engines, SAE Paper 900881, 1990. [12] Jenny E, Hansel J, Mayer A. The transient behaviour of supercharged passenger car diesel engines fitted with particulate traps, SAE Paper 890171, 1989. [13] I_ ßcing€ ur, Y., Dizel Motorlarının Asßırı Doldurulmasında Kullanılan Bir Basıncß Dalga Makinesinin Tasarımı ve € niversitesi Fen Bilimleri Enstit€ Kullanılabilirliginin Deneysel Analizi, Doktora Tezi, Gazi U us€ u, Ankara, 1996.