**The Effect of Injection Timing on the Environmental Performances of the Engine Fueled by LPG in the Liquid Phase**

Artur Jaworski, Hubert Kuszewski, Kazimierz Lejda and Adam Ustrzycki

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54604

## **1. Introduction**

110 Internal Combustion Engines

1967; 40: 206-210.

750468, 1975.

246-254.

Thermal Engineering, 1997.

John Wiley and Son; 2001.

Power 1990; 112(3): 341-348.

COMODIA 98, Kioto, 1998.

Engrs 1995; 209.

Journal of Mechanical Sciences 1975; 17(2): 97-124.

Numerical Mathematics 1996; 22: 225-236.

simulation. SAE Technical Paper 800029, 1980.

NASA Publication TN-D-4097, 1967.

gases. Journal Inst Fuel 1969; 42: 183-187.

[24] Jarquin G, Polupan G, Rodríguez GJ. Cálculo de los productos de combustión empleando métodos numéricos. Mecánica Computacional 2003; 22: 2442-2452. [25] McBride BJ, Gordon S. Fortran IV program for calculation of thermodynamic data.

[26] Gordon S, McBride BJ. Computer program for calculation of complex chemical equilibrium compositions, rocket performance, incident and reflected shocks, and

[27] Harker JH. The Calculation of equilibrium flame gas composition. Journal Inst Fuel

[28] Harker JH, Allen DA. The calculation of the temperature and composition of flame

[29] Olikara C, Borman GL. A computer program for calculating properties of equilibrium combustion products with some applications to IC. engines. SAE Technical Paper Nº

[30] Agrawal DD, Sharma SP, Gupta CP. The calculation of temperature and pressure of flame gases following constant volume combustion. Journal Inst Fuel 1977; 50: 121-124. [31] Agrawal D, Gupta CP. Computer program for constant pressure or constant volume combustion calculations in hydrocarbon-air ssystems. Transactions of the ASME 1977:

[32] Lapuerta M, Armas O, Hernández J. Diagnosis of DI diesel combustión from in-cylinder pressure signal by estimation of mean thernodynamic properties of the gas. Applied

[33] Araque J, Fygueroa S, Martín M. Modelado de la combustión en un MECH-CFR. In Memorias del IV Congreso Nacional de Ingeniería Mecánica, Mérida (Venezuela), 2001. [34] Ferguson C, Kirkpatrick A. Internal combustion: applied thermosciences. New York:

[35] Benson R, Annand W, Baruah P. A simulation model including intake and exhaust systems for a single cylinder four stroke cycle spark ignition engine. International

[36] Woodward J. Air standard modelling for closed cycle diesel engines. Proc Instn Mech

[37] Hull TE, Enright WH, Jackson KR. Runge-Kutta research at Toronto. Journal Applied

[38] Assanis DN. Valve event optimization in a spark-ignition engine. J Eng Gas Turbines

[39] Watson N, Pilley AD, Marzouk M. A Combustion correlation for diesel engine

[40] Miyamoto T, Hayashi K, Harada A, Sasaki S, Akagawa H, Tsujimura K. Numerical simulation of premixed lean diesel combustion in a DI engine. In Proceedings of

[41] Annand WJ. Heat transfer in the cylinders of reciprocating internal ccombustion engines. Proceedings of the Institution of Mechanical Engineers 1963; 177(1): 973-996. [42] Chapra S, Canale R. Métodos numéricos para ingenieros. México: Mc Graw Hil; 2002.

Chapman-Jouguet detonations. NASA Publication SP 273, 1971.

Gaseous fuels are widely used in internal combustion engines because of their properties and benefits. This is mainly due to their smaller burden on the environment and lower prices. They are used not only to power the traction engine in passenger cars or buses, but also in other applications, for example, to power the engines driven electric generators. Ever-expanding chain of filling stations increases the availability of these fuels, which also affects the development of such fuelling systems. Because of their advantages fuel injection systems with their own drivers are used increasingly. It provides a non-collision work of mentioned drivers with a gasoline engine drivers of the vehicles, providing the performance of an engine running on gas fuel comparable to one running on gasoline.

The use of LPG injection in the liquid phase makes it possible to have more precise fuel delivery, and even more limits amount of pollution emitted by the engine to the environment. The fuelling for internal combustion engines with LPG in liquid phase using injection system into the intake manifold is a solution very similar to conventional fuel systems (Hyun et al., 2002; Lee et al., 2003). This kind of fuelling to the cylinders allows to obtain performances of engine comparable to the performances obtained using petrol and diesel fuel system.

## **2. Adaptation of engine to fuelling with lpg in liquid phase at sequence injection**

The gas fuel system allowed the gas injection in the liquid phase was adapted to the engine, which in the original version was a compression ignition engine with symbol MD-111. This engine is a 6-cylinder Diesel engine with direct injection. The combustion chamber is made in the piston bowl and has a toroidal shape. By reducing the compression ratio and ignition

© 2012 Lejda et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Lejda et al., licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

system implementation, in the first stage, the engine to gas fuelling in the volatile phase has been adapted. The combustion chamber has been redesigned, gaining "cup" shape, whereby the compression ratio was also reduced from 16.5 to 9. The cylinder head was changed enabling to implementation a spark plug. To control the engine load, in the inlet system the throttle valve was installed.

The construction and operational parameters of modernized engine are summarized in Table 1. Next, the engine was further modernized in order to adapt gas fuel system enabling to sequence injection in the liquid phase.

As a gas system, the Vialle system was used (Fig. 1). The installation consists of:


The system was developed for mating with the ECU of petrol engine in the system MASTER-SLAVE. In this system, ECU of LPG fuel system uses injection duration determined by ECU of petrol engine for calculating the opening duration of gas injectors. Since the MD-111E engine did not have the electronic control unit, the primary issue was to develop a control unit, generating suitable values of the injection duration for the ECU of LPG fuel system.

The main components of a LPG, i.e. propane and butane, have low boiling points. These temperatures are respectively 231 K and 272.5 K, and are lower than the average ambient temperatures encountered during engine operation. Especially high temperatures are in the engine compartment of the vehicle (hot zone), where temperatures reach about 350 K. This causes the temperature rise in the fuel system, which leads to evaporation of fuel in the fuel pipes and formation of vapour-locks (Cipollone & Villante, 2000, 2001; Dutczak et al., 2003). Keeping gas in the liquid phase in such difficult conditions requires its compression. To obtain a stable injection of LPG in the liquid phase, the system was equipped with a pressure monitoring system. This function is performed by the pump (Fig. 2) placed in the fuel tank (Fig. 3) and pressure regulator (Fig. 4). The pressure regulator maintains the pressure in the supply system higher than the pressure in the tank. It allows to delivery fuel to injectors in liquid phase at every conditions of engine operation.

The liquid gas is pumped through a suitably shaped diaphragm pump. The pump has 5 chambers, which are integrated with the suction valves and power valve. The pump motor is a brushless alternating-current motor with permanent magnets. It is powered by DC, which is transformed into AC with a frequency controlled by an electronic control unit located in the assembly lid. The motor can be rotated with five different speeds 500, 1000, 1500, 2000, 2800 rpm. Speed control is realized by the ECU of LPG fuel system, depending on engine speed and load (injection duration). The pressure regulator is located between tank and gas injectors.


throttle valve was installed.

tank with fuel pump,

 LPG injectors, fuel pipes.

LPG fuel system.

tank and gas injectors.

to sequence injection in the liquid phase.

Electronic Control Unit (ECU) of LPG fuel system,

system implementation, in the first stage, the engine to gas fuelling in the volatile phase has been adapted. The combustion chamber has been redesigned, gaining "cup" shape, whereby the compression ratio was also reduced from 16.5 to 9. The cylinder head was changed enabling to implementation a spark plug. To control the engine load, in the inlet system the

The construction and operational parameters of modernized engine are summarized in Table 1. Next, the engine was further modernized in order to adapt gas fuel system enabling

The system was developed for mating with the ECU of petrol engine in the system MASTER-SLAVE. In this system, ECU of LPG fuel system uses injection duration determined by ECU of petrol engine for calculating the opening duration of gas injectors. Since the MD-111E engine did not have the electronic control unit, the primary issue was to develop a control unit, generating suitable values of the injection duration for the ECU of

The main components of a LPG, i.e. propane and butane, have low boiling points. These temperatures are respectively 231 K and 272.5 K, and are lower than the average ambient temperatures encountered during engine operation. Especially high temperatures are in the engine compartment of the vehicle (hot zone), where temperatures reach about 350 K. This causes the temperature rise in the fuel system, which leads to evaporation of fuel in the fuel pipes and formation of vapour-locks (Cipollone & Villante, 2000, 2001; Dutczak et al., 2003). Keeping gas in the liquid phase in such difficult conditions requires its compression. To obtain a stable injection of LPG in the liquid phase, the system was equipped with a pressure monitoring system. This function is performed by the pump (Fig. 2) placed in the fuel tank (Fig. 3) and pressure regulator (Fig. 4). The pressure regulator maintains the pressure in the supply system higher than the pressure in the tank. It allows to delivery fuel

The liquid gas is pumped through a suitably shaped diaphragm pump. The pump has 5 chambers, which are integrated with the suction valves and power valve. The pump motor is a brushless alternating-current motor with permanent magnets. It is powered by DC, which is transformed into AC with a frequency controlled by an electronic control unit located in the assembly lid. The motor can be rotated with five different speeds 500, 1000, 1500, 2000, 2800 rpm. Speed control is realized by the ECU of LPG fuel system, depending on engine speed and load (injection duration). The pressure regulator is located between

to injectors in liquid phase at every conditions of engine operation.

As a gas system, the Vialle system was used (Fig. 1). The installation consists of:


**Table 1.** Technical and operational data of MD-111E engine

**Figure 1.** Scheme of VIALLE fuelling system (Vialle, 2001): 1 – LPG tank, 2 – LPG pump, 3 – fuel pressure regulator, 4 – petrol ECU, 5 – LPG ECU, 6 – LPG injector, 7 – first oxygen sensor, 8 – second oxygen sensor, 9 – engine speed sensor, 10 – camshaft position sensor, 11 – coolant temperature sensor, 12 – air filter, 13 – exhaust gas catalyst, 14 – fuel type switch

The Effect of Injection Timing on the Environmental Performances of the Engine Fueled by LPG in the Liquid Phase 115

**Figure 2.** Unit of LPG pump (Vialle, 2001)

114 Internal Combustion Engines

Inlet valve timing:

Exhaust valve timing:

**<sup>1</sup> <sup>2</sup>**

**Table 1.** Technical and operational data of MD-111E engine

**7**

**9**

12 – air filter, 13 – exhaust gas catalyst, 14 – fuel type switch



25

**8**

**No. Name Value**

**4 5**

**<sup>6</sup> <sup>11</sup>**

**Figure 1.** Scheme of VIALLE fuelling system (Vialle, 2001): 1 – LPG tank, 2 – LPG pump, 3 – fuel pressure regulator, 4 – petrol ECU, 5 – LPG ECU, 6 – LPG injector, 7 – first oxygen sensor, 8 – second oxygen sensor, 9 – engine speed sensor, 10 – camshaft position sensor, 11 – coolant temperature sensor,

**13 12**

8 deg. before TDC 52 deg. after BDC

46 deg. before BDC 20 deg. after TDC

**3**

**14**

**10**

**Figure 3.** Scheme of tank with fuel pump (Vialle, 2001): 1 – pump body, 2 – inlet of body, 3 – tank wall, 4 – distance sleeve, 5 – inlet pipe, 6 – pump holder, 7 – pump, 8 – float, 9 – magnet

**Figure 4.** Scheme of LPG liquid phase injector (Vialle, 2001): 1 –electrical connection, 2 – injector body, 3 – ring fixing the injector to body, 4 – o-ring, 5 – fuel inlet socket, 6 – injector housing, 7 – adapter, 8 – outlet pipe

The pressure regulator includes solenoid valve opened and closed when the output valve of the tank is turned on. The pressure regulator is also a pressure control module and the pressure sensor. The liquid gas flows through the valve to the injectors and the excess returns via a pressure regulator to the tank. The pressure is keeping by the controller by 5 bars higher than the pressure in the tank and can be 7-30 bars (Cipollone & Villante, 2000; Vialle, 2001). For the injection of gas in liquid phase there were used the low-pass injectors which distinct from top-pass injectors commonly used in petrol fuel systems, the fuel is delivered below the injector coil. This causes less heating of the gas from the coil, which favors keeping the liquid phase in the injector. To prevent coarse pollutions the filter was placed before the inlet of gas into the injector (Fig. 4). Due to the low resistance of the injector coil, the pulse control was applied to reduce the currents flowing during operation of the injector. The gas is fed to the injectors with synthetic pipes which are fixed with reinforced plates to each other and are locked with screws. Because the exhaust manifold is located above the intake manifold, the injectors were mounted into the intake manifold from below near to the cylinder head. It allows to lead the gas almost directly onto the inlet valve.

## **3. Test stand and research method**

**1** 

**5** 

**7** 

**8** 

**Figure 4.** Scheme of LPG liquid phase injector (Vialle, 2001): 1 –electrical connection, 2 – injector body, 3 – ring fixing the injector to body, 4 – o-ring, 5 – fuel inlet socket, 6 – injector housing, 7 – adapter,

The pressure regulator includes solenoid valve opened and closed when the output valve of the tank is turned on. The pressure regulator is also a pressure control module and the pressure sensor. The liquid gas flows through the valve to the injectors and the excess returns via a pressure regulator to the tank. The pressure is keeping by the controller by 5 bars higher than the pressure in the tank and can be 7-30 bars (Cipollone & Villante, 2000; Vialle, 2001). For the injection of gas in liquid phase there were used the low-pass injectors which distinct from top-pass injectors commonly used in petrol fuel systems, the fuel is delivered below the injector coil. This causes less heating of the gas from the coil, which favors keeping the liquid phase in the injector. To prevent coarse pollutions the filter was placed before the inlet of gas into the injector (Fig. 4). Due to the low resistance of the injector coil, the pulse control was applied to reduce the currents flowing during operation of the injector. The gas is fed to the injectors with synthetic pipes which are fixed with reinforced plates to each other and are locked with screws. Because the exhaust manifold is located above the intake manifold, the injectors were mounted into the intake manifold from below near to the cylinder head. It allows to lead the gas almost directly onto the inlet valve.

116 Internal Combustion Engines

**2** 

**3** 

**4** 

**6** 

8 – outlet pipe

The goal of realized study was to determine the effect of injection timing on ecological parameters of the engine. The test stand with dynamometer has been equipped with the following functional units and measurement systems:

	- Chemiluminescent NOx analyzer of the type Pierburg CLD PM 2000,
	- Flame ionization hydrocarbon analyzer FID HC type of PIERBURG PM 2000,
	- four-gas exhaust gas analyzer (CO, CO2, HC, O2) of the type Bosch BEA 350 equipped with function for calculating the ratio of actual AFR to stoichiometry (Lambda) for the various fuels,

The engine mounted to the test stand (Fig. 5) is shown in figure 6.

**Figure 5.** Schema of test stand: 1 - engine, 2 – air flow meter, 3 – combustion gases analyzers, 4 – computer with data acquisition system, 5 - brake, 6 – measuring sensors, 7 – measuring amplifiers, 8 – container of LPG, 9 – fuel flow measurement, 10 – separator of signal

During tests the measurements of following exhaust ingredients were made: oxides of nitrogen (NOx), hydrocarbons (HC) and carbon monoxide (CO). Additionally, engine noise level was determined. Primarily the measurements was conducted for engine speed of n = 1500 rpm, required for co-operation with a power generator and with different loads.

An important parameter that affects both the operating parameters and the exhaust toxicity for sequential injection is the start of fuel injection (Hyun et al., 2002; Oh et al., 2002). For this reason a large part of the measurements was the analysis of the impact of the start of injection on obtained engine parameters and the emission of toxic ingredients in exhaust gases. The tests were performed with single and double injection. The start of injection was changed within the range shown in figure 7 and 8.

**Figure 6.** MDE-11 engine with sequence LPG injection system (for liquid phase) during test on stand

changed within the range shown in figure 7 and 8.

An important parameter that affects both the operating parameters and the exhaust toxicity for sequential injection is the start of fuel injection (Hyun et al., 2002; Oh et al., 2002). For this reason a large part of the measurements was the analysis of the impact of the start of injection on obtained engine parameters and the emission of toxic ingredients in exhaust gases. The tests were performed with single and double injection. The start of injection was

**Figure 6.** MDE-11 engine with sequence LPG injection system (for liquid phase) during test on stand

**Figure 7.** Tested injection starts with first signal disk sensor position: a) for single injection, b) for dual injection

**Figure 8.** Tested injection starts with second signal disk sensor position: a) for single injection, b) for dual injection

The measurement of noise level was realized with AS-120 meter located at a height of 1 m and 1 m from the engine on the side of electrical starter motor. The sound level was measured using a filter correction LA [dB] and without correction L [dB]. The microphone for sound recording was placed in the axis of the engine, between 3 and 4 cylinder, at distance of 1 m from the valve cover. There was used microphone AKG C1000S (Shure Beta-58) for sound recording cooperating with amplifier Behringer MX1804X and octave filter RFT OF 101-01000. The recording was performed with 16-bit sound card.

## **4. Test results**

Fig. 9 and 10 presents the performance of the engine, and fig. 11-14 shows the contour map (generalized performance map) for specific fuel consumption and the concentration of carbon monoxides, oxides of nitrogen and hydrocarbons. As we can see the maximum brake torque of the engine is larger than 770 Nm at an engine speed of 900 rpm and the maximum brake power of the engine is 125 kW at an engine speed of 1700 rpm.

Specific fuel consumption for an engine speed of 1500 rpm which is relevant to power generator is lowest at the maximum load and amounts to approximately 265 g/kWh. For this engine speed, the maximum CO concentration is approximately 0.3% and is higher at large loads. The concentration of NOx for mentioned engine speed ranges is from 40-550 ppm, reaching 160 -250 ppm for the large and medium loads. Hydrocarbon concentration amounts to from 15 ppm at small loads, up to 75 ppm at loads close to maximum.

The relationship between the injection starts of the LPG in liquid phase into a inlet manifold pipes and the concentration of CO2, CO, HC and NOx in the exhaust is shown on figures 15 and 16. At the starts of injection carried out at the opening of the intake valve, an increase in the concentration of NOx and hydrocarbons HC was observed versus the injection starts realized before opening the intake valve (fig. 15). The concentrations of CO and CO2 were undergone a slight changes in this case. At the injection starts carried out at the opening of the inlet valve is visible increase in the concentration of NOx at injection starts carried out from about 60 to 100 CA deg. after TDC during the intake stroke. Moreover an increase in the concentration of hydrocarbon HC and carbon monoxide CO at the injection starts carried out in the phase of closing the inlet valve from about 140 to 180 CA deg. after TDC at inlet stroke was observed (fig. 16). The injection realized at closing the inlet valve is also connected with the reduction of CO2 concentration.

Basing on the results for engine parameters and concentrations of hydrocarbons HC, oxides of nitrogen NOx, carbon monoxide CO in exhaust gas a right specific emissions were calculated. The calculation course of the specific emission was determined based on a set of International Standards ISO 8178 (ISO, 1999-2001). The calculation results are shown in figures 17-22.

The injection starts realized at closing the inlet valve (fig. 17 and 20) cause the increase in specific hydrocarbons emissions. Specific hydrocarbons emission decreases with increasing the injection duration (fuel quantity). Moreover we can see that specific NOX emission increases with long injection durations (higher load) and the injection starts realized at the opening of the inlet valve (fig. 18 and 21).

120 Internal Combustion Engines

**4. Test results** 

figures 17-22.

The measurement of noise level was realized with AS-120 meter located at a height of 1 m and 1 m from the engine on the side of electrical starter motor. The sound level was measured using a filter correction LA [dB] and without correction L [dB]. The microphone for sound recording was placed in the axis of the engine, between 3 and 4 cylinder, at distance of 1 m from the valve cover. There was used microphone AKG C1000S (Shure Beta-58) for sound recording cooperating with amplifier Behringer MX1804X and octave filter

Fig. 9 and 10 presents the performance of the engine, and fig. 11-14 shows the contour map (generalized performance map) for specific fuel consumption and the concentration of carbon monoxides, oxides of nitrogen and hydrocarbons. As we can see the maximum brake torque of the engine is larger than 770 Nm at an engine speed of 900 rpm and the maximum

Specific fuel consumption for an engine speed of 1500 rpm which is relevant to power generator is lowest at the maximum load and amounts to approximately 265 g/kWh. For this engine speed, the maximum CO concentration is approximately 0.3% and is higher at large loads. The concentration of NOx for mentioned engine speed ranges is from 40-550 ppm, reaching 160 -250 ppm for the large and medium loads. Hydrocarbon concentration

The relationship between the injection starts of the LPG in liquid phase into a inlet manifold pipes and the concentration of CO2, CO, HC and NOx in the exhaust is shown on figures 15 and 16. At the starts of injection carried out at the opening of the intake valve, an increase in the concentration of NOx and hydrocarbons HC was observed versus the injection starts realized before opening the intake valve (fig. 15). The concentrations of CO and CO2 were undergone a slight changes in this case. At the injection starts carried out at the opening of the inlet valve is visible increase in the concentration of NOx at injection starts carried out from about 60 to 100 CA deg. after TDC during the intake stroke. Moreover an increase in the concentration of hydrocarbon HC and carbon monoxide CO at the injection starts carried out in the phase of closing the inlet valve from about 140 to 180 CA deg. after TDC at inlet stroke was observed (fig. 16). The injection realized at closing the inlet valve is also

Basing on the results for engine parameters and concentrations of hydrocarbons HC, oxides of nitrogen NOx, carbon monoxide CO in exhaust gas a right specific emissions were calculated. The calculation course of the specific emission was determined based on a set of International Standards ISO 8178 (ISO, 1999-2001). The calculation results are shown in

The injection starts realized at closing the inlet valve (fig. 17 and 20) cause the increase in specific hydrocarbons emissions. Specific hydrocarbons emission decreases with increasing the injection duration (fuel quantity). Moreover we can see that specific NOX emission

amounts to from 15 ppm at small loads, up to 75 ppm at loads close to maximum.

RFT OF 101-01000. The recording was performed with 16-bit sound card.

brake power of the engine is 125 kW at an engine speed of 1700 rpm.

connected with the reduction of CO2 concentration.

**Figure 9.** MD-111E engine WOT diagram for double injection: Ne – engine power, Mo – torque, Ge – fuel consumption, ge – specific fuel consumption

**Figure 10.** MD-111E engine parameters for WOT operation: Ts – exhaust temperature, Bm – fuel amount HC – hydrocarbons, NOx – nitric oxides

**Figure 11.** Generalized performance map of MDE-111E LPG engine equipped with sequential injection system and catalytic converter

**Figure 12.** Contour map for concentration of monoxide carbon for MDE-111E LPG engine equipped with sequential injection system and catalytic converter

#### The Effect of Injection Timing on the Environmental Performances of the Engine Fueled by LPG in the Liquid Phase 123

122 Internal Combustion Engines

 

 

system and catalytic converter

 

 

0.018

0.2 0.15 0.1

0.08

0.15 0.2 0.4 0.55 0.8 <sup>1</sup> 1.2 1.4 1.8

0.06

0.04 0.06

Moment obrotowy, Mo [Nm]

Torque, Mo [Nm]

Moment obrotowy, Mo [Nm]

Torque, Mo [Nm]

800 900 1000 1100 1200 1300 1400 1500 1600 1700

<sup>360</sup> <sup>370</sup> <sup>380</sup> <sup>410</sup> <sup>420</sup> <sup>450</sup> <sup>475</sup> <sup>500</sup> <sup>550</sup> <sup>600</sup> <sup>700</sup> <sup>800</sup> <sup>900</sup> <sup>1000</sup>

 266 <sup>270</sup>

  10kW 20kW 30kW 40kW 50kW 60kW 70kW 80kW 90kW 100kW 110kW 120kW

 

 

 330 

 

 <sup>264</sup> <sup>268</sup> <sup>274</sup>

Prędkość obrotowa, n [obr/min]

Rotational speed, n [rpm]

**Figure 11.** Generalized performance map of MDE-111E LPG engine equipped with sequential injection

0.6 0.55

0.5

0.3 0.25

0.04

0.2

0.04

800 900 1000 1100 1200 1300 1400 1500 1600 1700

0.02 0.02 0.018 0.014

0.06

0.02

0.01 0.006 0.002

0.018 0.01 0.002

0.15

0.1

0.006

0.25

0.15

10kW 20kW 30kW 40kW 50kW 60kW 70kW 80kW 90kW 100kW 110kW 120kW

0.002

0.45 0.4

0.08

0.35

0.002

0.6 0.3 0.002

0.018 0.014 0.01

with sequential injection system and catalytic converter

0.2

0.04 0.006 0.02

0.06 0.08 0.1

Prędkość obrotowa, n [obr/min]

**Figure 12.** Contour map for concentration of monoxide carbon for MDE-111E LPG engine equipped

Rotational speed, n [rpm]

**Figure 13.** Contour map for concentration of oxides of nitrogen for MDE-111E LPG engine equipped with sequential injection system and catalytic converter

**Figure 14.** Contour map for concentration of hydrocarbons for MDE-111E LPG engine equipped with sequential injection system and catalytic converter

**Figure 15.** The effect of injection start on the concentration of CO, CO2, HC, NOx in the exhaust gas (single injection, n=1500 rpm, injection duration 4.6 ms) – for LPG in liquid phase

**Figure 16.** The effect of injection start on the concentration of CO, CO2, HC and NOx in the exhaust gas (single injection, n=900 rpm, injection time 5,5 ms) – for LPG in liquid phase

**CO2 [%]**

**80**

**GMP**

(single injection, n=900 rpm, injection time 5,5 ms) – for LPG in liquid phase

**11.2 11.6 12.0 12.4 12.8 CO2 [%]**

**HC [ppm]**

**100**

**120**

**HC [ppm]**

**140**

**160**

HC NOx CO CO2

**n=1500 obr/min wtrysk pojedynczy czas wtrysku 4,6 ms**

**n=1500 rpm single injection injetcion time 4,6 ms** 

**13.32 13.36 13.40 13.44 13.48**

> **-200 -160 -120 -80 -40 0 40 80 120 Pocz¹ tek wtrysku [° OWK]**

**Start of injection [CA deg]**

**Figure 15.** The effect of injection start on the concentration of CO, CO2, HC, NOx in the exhaust gas

**-40 -20 0 20 40 60 80 100 120 140 160 180 200 220 240 Pocz¹ tek wtrysku [OWK]**

**Figure 16.** The effect of injection start on the concentration of CO, CO2, HC and NOx in the exhaust gas

**Start of injection [CA deg]**

(single injection, n=1500 rpm, injection duration 4.6 ms) – for LPG in liquid phase

Wtrysk pojedynczy n=900 obr/min czas wtrysku 5,5 ms HC NOx CO CO2

**n=1500 rpm single injection injetcion time 4,6 ms** 

**Przebieg wzniosu zaworu dolotowego**

**Intake valve lift**

**GMP**

**Przebieg wzniosu zaworu dolotowego**

**Intake valve lift** 

**0.5 0.6 0.7 0.8**

**1.2 1.6 2.0 2.4 2.8**

**CO [%]**

**NOx [ppm]**

**NOx [ppm]**

**CO [%]**

**Figure 17.** Specific HC emission for the selected injection parameters (single injection, n=900 rpm)

**Figure 18.** Specific NOx emission for the selected injection parameters (single injection, n=900 rpm)

**Figure 19.** Specific CO emission for the selected injection parameters (single injection, n=900 rpm)

**Figure 20.** Specific HC emission for the selected injection parameters (single injection, n=1500 rpm)



20

60

**Start of injection [CA deg]**

100

140

180

20

60

**Start of injection [CA deg]**

100

140

180

**5,5**

**4,4**

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5 6 6,5 7 7,5 8 8,5 9 9,5 10 10,5

**HC [g/kWh]**

**6,6**

**Injection duration [ms]**

**8,4**

**Figure 20.** Specific HC emission for the selected injection parameters (single injection, n=1500 rpm)

220

**CO [g/kWh]**

**6,6**

<sup>220</sup> **Injection duration [ms]**

**8,4**

10-10,5 9,5-10 9-9,5 8,5-9 8-8,5 7,5-8 7-7,5 6,5-7 6-6,5 5,5-6 5-5,5 4,5-5 4-4,5 3,5-4 3-3,5 2,5-3 2-2,5 1,5-2 1-1,5 0,5-1 0-0,5

**Figure 19.** Specific CO emission for the selected injection parameters (single injection, n=900 rpm)

220-240 200-220 180-200 160-180 140-160 120-140 100-120 80-100 60-80 40-60 20-40 0-20

**Figure 21.** Specific NOx emission for the selected injection parameters (single injection, n=1500 rpm)

**Figure 22.** Specific CO emission for the selected injection parameters (single injection, n=1500 rpm)

At injection starts realized at closing the inlet valve the increase in specific CO emission is observed (fig. 19 and 22). The investigations show that specific CO emission decreases with injection duration (low load).

Table 2 presents the results of investigations on the effect of pilot and main injection on noise level generated by the engine. The study was conducted for an engine speed of n = 1500 rpm and three different loads – maximum, close to half of the maximum and not more than 10% of the maximum load. There was changed pilot injection advance pp relative to TDC (in the intake stroke), and the distance between pilot and main injection Δpz. The study was conducted at a fixed value of ignition advance wz = 20 CA deg.


**Table 2.** The effect of pilot and main injection timing on nosie level of the engine

**Figure 23.** Frequency spectrum of sound level at various injection timing

From table 2 and fig. 23 we can see that at an engine speed of 1500 rpm, regardless of the load, both the start injection of pilot fuel quantity pp and the start injection of main fuel quantity (characterized by the value of Δpz) do not have significant effect on the sound level and its frequency.

## **5. Conclusions**

128 Internal Combustion Engines

n [rpm]

injection duration (low load).

Mo [Nm]

> Sound level [dB]

At injection starts realized at closing the inlet valve the increase in specific CO emission is observed (fig. 19 and 22). The investigations show that specific CO emission decreases with

Table 2 presents the results of investigations on the effect of pilot and main injection on noise level generated by the engine. The study was conducted for an engine speed of n = 1500 rpm and three different loads – maximum, close to half of the maximum and not more than 10% of the maximum load. There was changed pilot injection advance pp relative to TDC (in the intake stroke), and the distance between pilot and main injection Δpz. The

> pp [CA deg]

1499 10,7 4,4 285 100 20 98 102 1491 6,6 4,6 285 30 20 98 102 1498 7,7 4,4 285 160 20 98 102 1500 45,4 4,6 225 100 20 97 101 1501 336,0 10,2 285 100 20 98 102 1501 337,5 10,4 285 30 20 98 102 1500 329,2 10,4 285 160 20 97 101 1501 349,3 10,8 225 100 20 97 100 1500 735,0 18,0 285 100 20 97 100 1501 714,9 18,2 285 30 20 97 100 1501 713,8 18,2 285 160 20 97 101 1500 728,2 17,2 225 100 20 97 101

pz [CA deg]

wz [CA deg]

LA [dB]

L [dB]

study was conducted at a fixed value of ignition advance wz = 20 CA deg.

**Table 2.** The effect of pilot and main injection timing on nosie level of the engine

**Figure 23.** Frequency spectrum of sound level at various injection timing

tinj [ms] The tested engine MD-111E reaches more than 125 kW at maximum tested speed, but at a speed of 1500 rpm, when cooperates with a power generator has a power output of 115 kW, what allows to cooperate with a power generator with a capacity of 125 kVA providing a sufficient surplus of power.

The researches show, that injection timing has a significant relationship with the emission of toxic ingredients in exhaust gases of the engine. LPG fuel injection carried out at closing of intake valve causes an increase in specific HC emission and specific CO emission. For the injection starts realized at opening of the intake valve an increase in the specific NOx emission is observed. Realized researches show, that at an engine speed of 1500 rpm, regardless of the load, both the start injection of pilot fuel quantity and the start injection of main fuel quantity do not have significant effect on the sound level and its frequency.

The final value of timing and mutual location of the fuel quantities (for pilot and main injection) with respect to TDC of the piston can be selected only because of the optimal operation and environmental performances of the engine. It greatly simplifies the problem of optimization of the ignition system and fuel injection system designed to fuelling using LPG in liquid phase at sequential injection system and at split of injection.

The application of fuel system with dual LPG sequential injection of liquid phase and the catalytic converter can achieve satisfactory environmental performances of the engine. The use of a turbocharger gives the possibility to increase the engine power obtained in broad range of engine speed with small modifications of fuel system.

The use of broadband oxygen sensor instead of the two state oxygen sensor can improve the control accuracy and precision of fuel delivery. In this way can be met more and more rising requirements connected with emission standards.

## **Author details**

Artur Jaworski, Hubert Kuszewski, Kazimierz Lejda and Adam Ustrzycki *Rzeszów University of Technology, Faculty of Mechanical Engineering and Aeronautics, Department of Automotive Vehicles and Internal Combustion Engines, Poland* 

## **6. References**

Cipollone, R., & Villante, C. (2000). *A/F and Liquid-Phase Control in LPG Injected Spark Ignition ICE*. SAE Technical Paper 2000-01-2974


PN-EN ISO 8178, part 1-4, 1999-2001

Training materials of Vialle. Kielce, 2001

**Engine Design, Control and Testing** 

130 Internal Combustion Engines

Cipollone, R., & Villante, C. (2001). A dynamical analysis of LPG vaporization in liquidphase injection systems. *International Workshop on "Modeling, Emissions and Control in* 

Dutczak, J., Golec, K., & Papuga, T. (2003). Niektóre problemy związane z wtryskowym zasilaniem silników ciekłym propanem-butanem. *VI Międzynarodowa Konferencja Naukowa SILNIKI GAZOWE 2003*, Zeszyty Naukowe Politechniki Częstochowskiej, pp.

Hyun, G., Oguma, M., & Goto, H. (2002). 3-D CFD analysis of the mixture formation process in an LPG DI SI engine for heavy duty vehicles. *Twelfth International Multidimensional* 

Lee, E., Park, J., Huh, K.Y., Choi, J., & Bae, C. (2003). *Simulation of fuel/air mixture formation for heavy duty liquid phase LPG injection* (*LPLI*) *engines*. SAE Technical Paper 2003-01-0636 Oh, S., Kim, S., Bae, C., Kim, C., & Kang, K. (2002). *Flame propagation characteristics in a heavy duty LPG engine with liquid phase port injection*. SAE Technical Paper 2002-01-1736

*Automotive Engines" MECA'01,* University of Salerno, Italy, September 2001

296-303, ISBN 83-7193-208-1, Częstochowa, 2003

PN-EN ISO 8178, part 1-4, 1999-2001 Training materials of Vialle. Kielce, 2001

*Engine Modeling User's Group Meeting Agenda*, Detroit, 2002
