Application of Biodiesel

**Chapter 4**

**Abstract**

any major changes in the engines.

**1. Introduction**

rupture of the diaphragm.

**71**

regions formed after the diaphragm rupture.

Shock Tube Combustion Analysis

*Claudio Marcio Santana and Jose Eduardo Mautone Barros*

The shock tube is a metal tube that the gas at low pressure and high pressure are

separated by a diaphragm. When the diaphragm (make of material copper and aluminum) breaks on predetermined conditions (high pressure in this case) produces shock waves that move from the high-pressure chamber (known the compression chamber or Driver section) for low pressure chamber (known the expansion chamber or Driven section). The objective of this work is the correlate the ignition delay times of convectional Diesel and Biodiesel from soybean oil measured in a shock tube. The results were correlated with the cetane number of respective fuels and compared with the ignition delay times of Diesel and Biodiesel with cetane numbers of known. The ignition delay time of biodiesel from soybean oil was approximately three times greater than the ignition delay time of convectional Diesel. The contribution of this work is that it shows why pure biodiesel should not be used as substitutes for Diesel compression ignition engines without

**Keywords:** diesel ignition delay time, biodiesel ignition delay time, shock tube,

Shock tube is an equipment used to study gas flow in different areas of engineering and operating conditions, such as: shock wave movement, aerodynamic flows under different temperature and pressure conditions, gas compressibility and fuel combustion. The equipment is constructed by a metal tube separated by a diaphragm, which divides the equipment into two sections. The high-pressure section is called the driver section while the low-pressure section is called the driven section. The diaphragm separating the two sections is designed to withstand a certain pressure, when that pressure is reached the diaphragm breaks and a compression wave is formed and moves towards the driven section. Instantly an expansion wave is formed and propagates towards the driver section. This movement of the gas mass inside the shock tube causes an increase in pressure and temperature in the driven section and a reduction in pressure and temperature in the driver section, [1, 2]. The **Figure 1** shows the driver and driven sections of shock tube before the

After the diaphragm rupture is formed inside the shock tube, the contact surface, a region that did not feel the passage of the shock wave, a second region that felt the effects of the passage of the shock wave, a third region that did not feel the passage of the expansion wave and a fourth region that felt the effects of the expansion wave passage, [2, 4]. The **Figure 2** shows the contact surfaces and four

diesel cetane number, biodiesel from soybean oil cetane number

## **Chapter 4** Shock Tube Combustion Analysis

*Claudio Marcio Santana and Jose Eduardo Mautone Barros*

#### **Abstract**

The shock tube is a metal tube that the gas at low pressure and high pressure are separated by a diaphragm. When the diaphragm (make of material copper and aluminum) breaks on predetermined conditions (high pressure in this case) produces shock waves that move from the high-pressure chamber (known the compression chamber or Driver section) for low pressure chamber (known the expansion chamber or Driven section). The objective of this work is the correlate the ignition delay times of convectional Diesel and Biodiesel from soybean oil measured in a shock tube. The results were correlated with the cetane number of respective fuels and compared with the ignition delay times of Diesel and Biodiesel with cetane numbers of known. The ignition delay time of biodiesel from soybean oil was approximately three times greater than the ignition delay time of convectional Diesel. The contribution of this work is that it shows why pure biodiesel should not be used as substitutes for Diesel compression ignition engines without any major changes in the engines.

**Keywords:** diesel ignition delay time, biodiesel ignition delay time, shock tube, diesel cetane number, biodiesel from soybean oil cetane number

#### **1. Introduction**

Shock tube is an equipment used to study gas flow in different areas of engineering and operating conditions, such as: shock wave movement, aerodynamic flows under different temperature and pressure conditions, gas compressibility and fuel combustion. The equipment is constructed by a metal tube separated by a diaphragm, which divides the equipment into two sections. The high-pressure section is called the driver section while the low-pressure section is called the driven section. The diaphragm separating the two sections is designed to withstand a certain pressure, when that pressure is reached the diaphragm breaks and a compression wave is formed and moves towards the driven section. Instantly an expansion wave is formed and propagates towards the driver section. This movement of the gas mass inside the shock tube causes an increase in pressure and temperature in the driven section and a reduction in pressure and temperature in the driver section, [1, 2]. The **Figure 1** shows the driver and driven sections of shock tube before the rupture of the diaphragm.

After the diaphragm rupture is formed inside the shock tube, the contact surface, a region that did not feel the passage of the shock wave, a second region that felt the effects of the passage of the shock wave, a third region that did not feel the passage of the expansion wave and a fourth region that felt the effects of the expansion wave passage, [2, 4]. The **Figure 2** shows the contact surfaces and four regions formed after the diaphragm rupture.

#### **Figure 1.**

*Driver and driven sections of the shock tube before rupture of the diaphragm (adapted from [3]).*

sections, these sections are not affected by the passage of the shock and expansion waves. Behind the shock wave, pressure, density and temperature increase, while behind the expansion wave these variables decrease, [3]. The **Figure 5** shows the conditions of pressure and temperature in the driver and driven sections after the

*Condition of pressure and temperature in the driver and driven sections before the diagram rupture (adapted*

The **Figure 6** shows the conditions of shock tube after reflection shock wave and

*Condition of pressure and temperature in the driver and driven sections after the diagram rupture (adapted*

*Conditions of shock tube after reflection shock wave and reflection expansion wave (adapted from [3]).*

diagram rupture.

**Figure 4.**

*from [3]).*

**Figure 5.**

*from [3]).*

**Figure 6.**

**73**

reflection expansion wave.

*Shock Tube Combustion Analysis*

*DOI: http://dx.doi.org/10.5772/intechopen.96870*

#### **Figure 2.**

*Contact surfaces and four regions formed after the diaphragm rupture (adapted from [3]).*

The incident shock wave is reflected and propagates towards the driver section when it reaches the closed end of the shock tube driven section. The reflected shock wave superimposes the motion of the incident shock wave, this superposition increases temperature and pressure in the driven section. The reflected shock wave is responsible for causing the dissociation and ionization of the gas inside the shock tube, [2, 4]. The **Figure 3** shows the propagation shock wave, reflected wave, expansion wave, reflected expansion wave and the contact surface after the diaphragm rupture shock tube.

The shock force is determined by the pressure ratio (P4/P1) and speed of sound propagation (a4/a1) between the driver and driven sections, [3]. The **Figure 4** shows the conditions of pressure and temperature in the driver and driven sections before the diagram rupture.

In the front of the shock and expansion waves the pressure, density and temperature do not varied in relation to the initial conditions in the driver and driven

#### **Figure 3.**

*Shock wave, reflected wave, expansion wave, reflected expansion wave and the contact surface after the diaphragm rupture shock tube.*

*Shock Tube Combustion Analysis DOI: http://dx.doi.org/10.5772/intechopen.96870*

#### **Figure 4.**

The incident shock wave is reflected and propagates towards the driver section when it reaches the closed end of the shock tube driven section. The reflected shock wave superimposes the motion of the incident shock wave, this superposition increases temperature and pressure in the driven section. The reflected shock wave is responsible for causing the dissociation and ionization of the gas inside the shock tube, [2, 4]. The **Figure 3** shows the propagation shock wave, reflected wave, expansion wave, reflected expansion wave and the contact surface after the dia-

*Driver and driven sections of the shock tube before rupture of the diaphragm (adapted from [3]).*

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

*Contact surfaces and four regions formed after the diaphragm rupture (adapted from [3]).*

The shock force is determined by the pressure ratio (P4/P1) and speed of sound

In the front of the shock and expansion waves the pressure, density and temperature do not varied in relation to the initial conditions in the driver and driven

propagation (a4/a1) between the driver and driven sections, [3]. The **Figure 4** shows the conditions of pressure and temperature in the driver and driven sections

*Shock wave, reflected wave, expansion wave, reflected expansion wave and the contact surface after the*

phragm rupture shock tube.

**Figure 1.**

**Figure 2.**

**Figure 3.**

**72**

*diaphragm rupture shock tube.*

before the diagram rupture.

*Condition of pressure and temperature in the driver and driven sections before the diagram rupture (adapted from [3]).*

sections, these sections are not affected by the passage of the shock and expansion waves. Behind the shock wave, pressure, density and temperature increase, while behind the expansion wave these variables decrease, [3]. The **Figure 5** shows the conditions of pressure and temperature in the driver and driven sections after the diagram rupture.

The **Figure 6** shows the conditions of shock tube after reflection shock wave and reflection expansion wave.

#### **Figure 5.**

*Condition of pressure and temperature in the driver and driven sections after the diagram rupture (adapted from [3]).*

#### **Figure 6.**

*Conditions of shock tube after reflection shock wave and reflection expansion wave (adapted from [3]).*

#### **2. Analytical solution shock tube for ideal gas**

The speed of sound for each state gas must be calculated using the Eq. (1).

$$
\mathfrak{a} = \sqrt{\chi \overline{\mathcal{R} \! T}} \tag{1}
$$

The calculation of the speed of the shock wave can be determined by the

dent shock wave pressure using the Eq. (10), [3].

**3. Works carried out in shock tube**

*P*5 *P*2 ¼

*T*5 *T*2

To determine the relationship between reflected shock wave pressure and inci-

<sup>1</sup> <sup>þ</sup> *<sup>γ</sup>*1þ<sup>1</sup> *γ*1�1 *P*1 *P*2

With the ratio compression known the ratio reflected shock wave temperature

*γ*1þ1 *<sup>γ</sup>*1�<sup>1</sup> <sup>þ</sup> *<sup>P</sup>*<sup>5</sup> *P*2

The temperature and pressure behind the reflected shock wave can be calculated

<sup>1</sup> <sup>þ</sup> *<sup>γ</sup>*1þ<sup>1</sup> *γ*1�1 *P*5 *P*2

!

!

*P*2

*γ*1þ1 *<sup>γ</sup>*1�<sup>1</sup> <sup>þ</sup> <sup>2</sup> � *<sup>P</sup>*<sup>1</sup>

and incident shock wave temperature can be determined by Eq. (11), [3].

¼ *P*5 *P*2

determined from the velocity of the gas driven and wave velocity, [3].

knowing only the Mach number of the incident shock wave. This value can be

[5] used a shock tube to measure the ignition delay times of mixture with ethanol, n-heptane and iso-octane and mixture with ethanol, iso-octane, n-heptane and toluene. The tests were performed at temperatures ranging from 690 to 1200 K and pressures at 10, 30 and 50 bar. For testing mixture with ethanol, n-heptane and iso-octane were found delay times ranging from 120 to 6230 microseconds, for testing mixture with iso-octane, toluene, n-heptane and ethanol were found delay times ranging from 28 to 8731 microseconds and for testing mixture with isooctane, toluene and n-heptane were found ignition delay times ranging from 180 to 1060 microseconds. [6] also used a shock tube to measure the ignition delay times of mixture with n-heptane and n-butanol. The tests were performed at temperatures ranging from 1200 to 1500 K, pressures at 2 and 10 atm and equivalence ratios at 0.5 and 1. For testing with pure n-heptane were found delay times ranging from 90 to 1230 microseconds, for testing mixture with pure n-butanol were found delay times ranging from 120 to 950 microseconds and for testing mixture with n-heptane and n-butanol were found ignition delay times ranging from 30 to 1010 microseconds. [7] also conducted shock tube tests with n-heptane, iso-octane and ethanol. The tests were performed at temperatures ranging from 690 to 1200 K and pressures at 10, 30 and 50 bar. For testing at 10 bar and mixture with n-heptane, isooctane and ethanol were found ignition delay times ranging from 181 to 2870 microseconds. For testing at 30 bar and mixture with n-heptane, iso-octane and ethanol were found ignition delay times ranging from 172 to 7800 microseconds. For testing at 50 bar and mixture with n-heptane, iso-octane and ethanol were found ignition delay times ranging from 115 to 7690 microseconds. For testing at 10 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were found ignition delay times ranging from 245 to 4600 microseconds. For testing at 30 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were found ignition delay times ranging from 191 to 8320 microseconds. For testing at 10 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were

*VR* ¼ *MRa*<sup>2</sup> � *V*<sup>2</sup> (9)

(10)

(11)

Eq. (9), [3].

*Shock Tube Combustion Analysis*

*DOI: http://dx.doi.org/10.5772/intechopen.96870*

**75**

Where γ is the ratio of specific heats of the gas, *R* is the universal gas constant and *T* is the gas temperature in the respective regions of the shock tube. The Mach number can be determined using the Eq. (2), [3].

$$\frac{P\_4}{P\_1} = \frac{\gamma\_{1-1}}{\gamma\_{1+1}} \left[ \frac{2\gamma\_1}{\gamma\_{1-1}} M\_s^2 - 1 \right] \left[ 1 - \frac{\frac{\gamma\_4}{\gamma\_{4+1}} \left( \frac{d\_1}{d\_4} \right) \left( M\_s^2 - 1 \right)}{M\_s} \right]^{-\frac{2\gamma\_4}{\gamma\_{4-1}}} \tag{2}$$

Where *Ms* is the shock wave Mach number, the subscript 1 denotes the properties of the driven section and the subscript 4 denotes the properties of the driver section. The pressure ratio (P2/P1) on both sides of the shock wave can be calculated using the Eq. (3), [3].

$$\frac{P\_2}{P\_1} = 1 + \frac{2\gamma\_1}{\gamma\_1 + 1} \left(M\_s^2 - 1\right) \tag{3}$$

The pressure ratio (P2/P1) can be used to determine the temperature ratio (T2/ T1) on both sides of the shock wave using the Eq. (4), [3].

$$\frac{T\_2}{T\_1} = \frac{P\_2}{P\_1} \left( \frac{\frac{\frac{\mathcal{I}\_1 + 1}{\mathcal{I}\_1 - 1} + \frac{P\_2}{P\_1}}{\mathbf{1} + \frac{\mathcal{I}\_1 + 1}{\mathcal{I}\_1 - 1} \frac{P\_2}{P\_1}} \right) \tag{4}$$

The shock wave reflected Mach number *MR* depend the velocity of the incident shock wave and can be calculated by the Eq. (5), [3].

$$\frac{\mathcal{M}\_R}{\mathcal{M}\_R^2 - 1} = \frac{\mathcal{M}\_s}{\mathcal{M}\_s^2 - 1} \sqrt{\mathbf{1} + \frac{2(\boldsymbol{\gamma}\_1 - \mathbf{1})}{\left(\boldsymbol{\gamma}\_1 + \mathbf{1}\right)^2} \left(\mathcal{M}\_s^2 - \mathbf{1}\right) \left(\boldsymbol{\gamma}\_1 + \frac{\mathbf{1}}{\mathcal{M}\_s^2}\right)}\tag{5}$$

The increased pressure of the shock wave reflected *P5* depend the speed of the incident shock wave, this ratio can be calculated by the Eq. (6), [3].

$$\frac{P\_5}{P\_2} = 1 + \frac{2\gamma\_1}{\gamma\_1 + 1} \left(M\_R^2 - 1\right) \tag{6}$$

The Eq. (7) shows the relationship of the motion of the mass gas behind the shock wave and the reflected shock wave, [3].

$$\frac{2a\_1}{\gamma\_1 + 1} \left( M\_\sharp - \frac{1}{M\_\sharp} \right) = \frac{2a\_2}{\gamma\_1 + 1} \left( M\_R - \frac{1}{M\_R} \right) \tag{7}$$

The calculations involving speed of the gas molecules can be determined by the Eq. (8), [3].

$$\text{Mach } \mathbf{M} = \frac{V}{a} \tag{8}$$

*Shock Tube Combustion Analysis DOI: http://dx.doi.org/10.5772/intechopen.96870*

**2. Analytical solution shock tube for ideal gas**

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

number can be determined using the Eq. (2), [3].

2*γ*<sup>1</sup> *γ*1�<sup>1</sup> *M*<sup>2</sup> *<sup>s</sup>* � 1 � �

> *P*2 *P*1

T1) on both sides of the shock wave using the Eq. (4), [3].

shock wave and can be calculated by the Eq. (5), [3].

<sup>¼</sup> *Ms M*<sup>2</sup> *<sup>s</sup>* � 1

shock wave and the reflected shock wave, [3].

Eq. (8), [3].

**74**

2*a*<sup>1</sup> *γ*<sup>1</sup> þ 1

*MR M*<sup>2</sup> *<sup>R</sup>* � 1 *T*2 *T*1 ¼ *P*2 *P*1

1 þ

incident shock wave, this ratio can be calculated by the Eq. (6), [3].

¼ 1 þ

*Ms* � <sup>1</sup> *Ms* � �

*P*5 *P*2 ¼ 1 þ

<sup>¼</sup> *<sup>γ</sup>*1�<sup>1</sup> *γ*1þ<sup>1</sup>

*P*4 *P*1

calculated using the Eq. (3), [3].

The speed of sound for each state gas must be calculated using the Eq. (1).

*<sup>a</sup>* <sup>¼</sup> ffiffiffiffiffiffiffiffiffi

Where γ is the ratio of specific heats of the gas, *R* is the universal gas constant and *T* is the gas temperature in the respective regions of the shock tube. The Mach

1 �

Where *Ms* is the shock wave Mach number, the subscript 1 denotes the properties of the driven section and the subscript 4 denotes the properties of the driver section. The pressure ratio (P2/P1) on both sides of the shock wave can be

> 2*γ*<sup>1</sup> *γ*<sup>1</sup> þ 1

The pressure ratio (P2/P1) can be used to determine the temperature ratio (T2/

*γ*1þ1 *<sup>γ</sup>*1�<sup>1</sup> <sup>þ</sup> *<sup>P</sup>*<sup>2</sup> *P*1

The shock wave reflected Mach number *MR* depend the velocity of the incident

2 *γ*ð Þ <sup>1</sup> � 1 *<sup>γ</sup>*ð Þ <sup>1</sup> <sup>þ</sup> <sup>1</sup> <sup>2</sup> *<sup>M</sup>*<sup>2</sup>

The increased pressure of the shock wave reflected *P5* depend the speed of the

2*γ*<sup>1</sup> *γ*<sup>1</sup> þ 1

The Eq. (7) shows the relationship of the motion of the mass gas behind the

<sup>¼</sup> <sup>2</sup>*a*<sup>2</sup> *γ*<sup>1</sup> þ 1

The calculations involving speed of the gas molecules can be determined by the

*Mach M* <sup>¼</sup> *<sup>V</sup>*

*a*

*M*<sup>2</sup>

<sup>1</sup> <sup>þ</sup> *<sup>γ</sup>*1þ<sup>1</sup> *γ*1�1 *P*2 *P*1

!

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

*<sup>s</sup>* � <sup>1</sup> � � *<sup>γ</sup>*<sup>1</sup> <sup>þ</sup>

*MR* � <sup>1</sup> *MR*

� �

vu ! ut (5)

*M*<sup>2</sup>

2 4 *<sup>γ</sup>*4�<sup>1</sup> *<sup>γ</sup>*4þ<sup>1</sup> *a*1 *a*4 � �

*M*<sup>2</sup> *<sup>s</sup>* � <sup>1</sup> � �

*Ms*

*γRT* p (1)

3 5

*<sup>s</sup>* � <sup>1</sup> � � (3)

1 *M*<sup>2</sup> *s*

*<sup>R</sup>* � <sup>1</sup> � � (6)

� <sup>2</sup>*γ*<sup>4</sup> *<sup>γ</sup>*4�<sup>1</sup>

(2)

(4)

(7)

(8)

The calculation of the speed of the shock wave can be determined by the Eq. (9), [3].

$$V\_R = M\_R a\_2 - V\_2 \tag{9}$$

To determine the relationship between reflected shock wave pressure and incident shock wave pressure using the Eq. (10), [3].

$$\frac{P\_5}{P\_2} = \left(\frac{\frac{\gamma\_1 + 1}{\gamma\_1 - 1} + 2 - \frac{P\_1}{P\_2}}{\mathbf{1} + \frac{\gamma\_1 + 1}{\gamma\_1 - 1}\frac{P\_1}{P\_2}}\right) \tag{10}$$

With the ratio compression known the ratio reflected shock wave temperature and incident shock wave temperature can be determined by Eq. (11), [3].

$$\frac{T\_5}{T\_2} = \frac{P\_5}{P\_2} \left( \frac{\frac{\gamma\_1 + 1}{\gamma\_1 - 1} + \frac{P\_5}{P\_2}}{1 + \frac{\gamma\_1 + 1}{\gamma\_1 - 1} \frac{P\_5}{P\_2}} \right) \tag{11}$$

The temperature and pressure behind the reflected shock wave can be calculated knowing only the Mach number of the incident shock wave. This value can be determined from the velocity of the gas driven and wave velocity, [3].

#### **3. Works carried out in shock tube**

[5] used a shock tube to measure the ignition delay times of mixture with ethanol, n-heptane and iso-octane and mixture with ethanol, iso-octane, n-heptane and toluene. The tests were performed at temperatures ranging from 690 to 1200 K and pressures at 10, 30 and 50 bar. For testing mixture with ethanol, n-heptane and iso-octane were found delay times ranging from 120 to 6230 microseconds, for testing mixture with iso-octane, toluene, n-heptane and ethanol were found delay times ranging from 28 to 8731 microseconds and for testing mixture with isooctane, toluene and n-heptane were found ignition delay times ranging from 180 to 1060 microseconds. [6] also used a shock tube to measure the ignition delay times of mixture with n-heptane and n-butanol. The tests were performed at temperatures ranging from 1200 to 1500 K, pressures at 2 and 10 atm and equivalence ratios at 0.5 and 1. For testing with pure n-heptane were found delay times ranging from 90 to 1230 microseconds, for testing mixture with pure n-butanol were found delay times ranging from 120 to 950 microseconds and for testing mixture with n-heptane and n-butanol were found ignition delay times ranging from 30 to 1010 microseconds. [7] also conducted shock tube tests with n-heptane, iso-octane and ethanol. The tests were performed at temperatures ranging from 690 to 1200 K and pressures at 10, 30 and 50 bar. For testing at 10 bar and mixture with n-heptane, isooctane and ethanol were found ignition delay times ranging from 181 to 2870 microseconds. For testing at 30 bar and mixture with n-heptane, iso-octane and ethanol were found ignition delay times ranging from 172 to 7800 microseconds. For testing at 50 bar and mixture with n-heptane, iso-octane and ethanol were found ignition delay times ranging from 115 to 7690 microseconds. For testing at 10 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were found ignition delay times ranging from 245 to 4600 microseconds. For testing at 30 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were found ignition delay times ranging from 191 to 8320 microseconds. For testing at 10 bar and mixture with n-heptane, iso-octane, toluene and di-isobutylene were

4000 microseconds. [16] also conducted shock tube tests with conventional and alternative jet fuels, alcohol to jet, direct sugar to hydrocarbon, biodiesel-like fuel, n-heptane, n-dodecane, m-xylene and iso-dodecane. Were found ignition delay times for all fuel testing ranging from 20 to 3200 microseconds. The tests were performed at temperatures from 980 to 1800 K, pressures at 16 atm and equiva-

**4. Experimental measuring the ignition delay times of the convectional**

The experiments were conducted in the heated shock tube facility of the Mobility Technology Center (CTM) of Federal University of Minas Gerais (UFMG). The shock tube has a 3 m long driver section and a 3 m long driven section with an internal diameter of 97.20 mm. Aluminum diaphragm of 0.4 mm thickness divided the driver and driven sections before each experiment. The experiments were carried out with convectional Diesel and pure biodiesel from soy oil. The convectional Diesel used in this study is normally fuel found at gas stations and it has a cetane number of 43. The pure biodiesel used in this study was derived from a process of refining oil from soy oil and it has a cetane number of 38. The instrumentation within the shock tube used for the experiment included three pressure sensors (P1, P2 and P3), two temperature sensors (T3 and T1), a luminosity detection sensor (L1) and a fuel injector (FI). In the present work a mixture of the Nitrogen (N2) and Argon (Ar) gases was used as the driver gas to obtain a longer test time. The **Figure 7** shows the position of the sensors, fuel injector, aluminum diaphragm location and mixture of the Nitrogen and Argon inlet in the shock tube. The pressure sensor P3 (located at 1700 mm before the aluminum diaphragm) was used to monitor the pressure in the driver section and the diaphragm rupture pressure. The pressure sensor P2 (located at 700 mm after the aluminum diaphragm) was used to indicates the moment of passage of the shock wave after diaphragm rupture. This information is used to control and define the fuel injection timing. The pressure sensor P1 (located at 2700 mm after the diaphragm) was used to indicates the moment of passage of shock in region 1 where combustion occurs. For monitor the temperature in the driver section was used an analog temperature sensor T3. For monitor and control the temperature in the driven section was used a temperature sensor T1 with the same characteristics that the temperature sensor T3 used in driver section. The luminosity detection sensor L1 was used to indicates the

*Position of the sensors, fuel injector, aluminum diaphragm location and mixture of the nitrogen and argon inlet*

**diesel and biodiesel from soybean oil using a shock tube**

lence ratio at 0.5.

*Shock Tube Combustion Analysis*

*DOI: http://dx.doi.org/10.5772/intechopen.96870*

**Figure 7.**

**77**

*in the shock tube (adapted from [17]).*

found ignition delay times ranging from 149 to 10100 microseconds. [8] also conducted shock tube tests with n-heptane and were found ignition delay times ranging from 1220 to 10600 microseconds. The tests were performed at temperatures ranging from 651 to 823 K, pressures at 6.1 and 7.4 atm and equivalence ratio of 0.75. [9] also conducted shock tube tests with propane and were found ignition delay times ranging from 100 to 11000 microseconds for testing at 6 atm. Were found ignition delay times ranging from 200 to 11000 microseconds for testing at 24 atm and were found ignition delay times ranging from 300 to 600 microseconds for testing at 60 atm. The tests were performed at temperatures ranging from 980 to 1400 K and equivalence ratio 0.5. [10] also conducted shock tube tests with methyl butanoate and were found ignition delay times ranging from 19630 to 24180 microseconds for testing at 10.2 atm. The tests were performed at temperatures from 985 K and equivalence ratio 0.3. [11] also conducted shock tube tests with methyl octanoate, n-nonane and methylcyclohexane. The tests were performed at temperatures ranging from 1263 to 1672 K, pressures at 1.5 and 10 atm and equivalence ratio 0.5, 1 and 2. For tests with equivalence ratio 0.5 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 40 to 1000 microseconds, for n-nonane were found delay times ranging from 100 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 100 to 1200 microseconds. For tests with equivalence ratio 0.5 at 10 atm were found for methyl octanoate ignition delay times ranging from 110 to 800 microseconds, for n-nonane were found delay times ranging from 90 to 900 microseconds and for methylcyclohexane were found delay times ranging from 90 to 1050 microseconds. For tests with equivalence ratio 1 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 120 to 1000 microseconds, for n-nonane were found delay times ranging from 90 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 120 to 1100 microseconds. For tests with equivalence ratio 1 at 10 atm were found for methyl octanoate ignition delay times ranging from 80 to 1000 microseconds, for n-nonane were found delay times ranging from 80 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 150 to 1100 microseconds. For tests with equivalence ratio 2 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 100 to 900 microseconds, for n-nonane and for methylcyclohexane were found delay times ranging from 100 to 1100 microseconds. For tests with equivalence ratio 2 at 10 atm were found for methyl octanoate and methylcyclohexane ignition delay times ranging from 90 to 1000 microseconds, for n-nonane were found delay times ranging from 100 to 1100 microseconds. [12] also conducted shock tube tests with methyl stearate, methyl oleate, methyl linoleate, methyl linolenate, and methyl palmitate and were found ignition delay times for all fuel testing ranging from 200 to 90000 microseconds for testing at 13.5 bar. The tests were performed at temperatures from 700 to 1100 K and equivalence ratio 1. [13] also conducted shock tube tests with jets fuels, rocket propellants, diesel fuel and gasoline fuel and were found ignition delay times for all fuel testing ranging from 100 to 1900 microseconds for testing at pressure from 6 to 60 atm. The tests were performed at temperatures from 1000 to 1400 K and equivalence ratio 0.85 and 1.15. [14] also conducted shock tube tests with mixture of biodiesel with diesel fuel and were found ignition delay times for all fuel testing ranging from 60 to 2600 microseconds for testing at pressure at 0.12 Mpa. The tests were performed at temperatures from 1174 to 1685 K and equivalence ratio 0.5, 1 and 1.5. [15] also conducted shock tube tests with diesel fuel and alternative hydro processed jet fuels. The tests were performed at temperatures from 650 to 1300 K, pressures from 0.8 to 80 atm and equivalence ratio 0.25 to 1.5. For testing with jet fuels were found ignition delay times ranging from 60 to 8000 microseconds and for testing with diesel fuels were found ignition delay times ranging from 90 to

#### *Shock Tube Combustion Analysis DOI: http://dx.doi.org/10.5772/intechopen.96870*

found ignition delay times ranging from 149 to 10100 microseconds. [8] also conducted shock tube tests with n-heptane and were found ignition delay times ranging from 1220 to 10600 microseconds. The tests were performed at temperatures ranging from 651 to 823 K, pressures at 6.1 and 7.4 atm and equivalence ratio of 0.75. [9] also conducted shock tube tests with propane and were found ignition delay times ranging from 100 to 11000 microseconds for testing at 6 atm. Were found ignition delay times ranging from 200 to 11000 microseconds for testing at 24 atm and were found ignition delay times ranging from 300 to 600 microseconds for testing at 60 atm. The tests were performed at temperatures ranging from 980 to 1400 K and equivalence ratio 0.5. [10] also conducted shock tube tests with methyl butanoate and were found ignition delay times ranging from 19630 to 24180 microseconds for testing at 10.2 atm. The tests were performed at temperatures from 985 K and equivalence ratio 0.3. [11] also conducted shock tube tests with methyl octanoate, n-nonane and methylcyclohexane. The tests were performed at temperatures ranging from 1263 to 1672 K, pressures at 1.5 and 10 atm and equivalence ratio 0.5, 1 and 2. For tests with equivalence ratio 0.5 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 40 to 1000 microseconds, for n-nonane were found delay times ranging from 100 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 100 to 1200 microseconds. For tests with equivalence ratio 0.5 at 10 atm were found for methyl octanoate ignition delay times ranging from 110 to 800 microseconds, for n-nonane were found delay times ranging from 90 to 900 microseconds and for methylcyclohexane were found delay times ranging from 90 to 1050 microseconds. For tests with equivalence ratio 1 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 120 to 1000 microseconds, for n-nonane were found delay times ranging from 90 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 120 to 1100 microseconds. For tests with equivalence ratio 1 at 10 atm were found for methyl octanoate ignition delay times ranging from 80 to 1000 microseconds, for n-nonane were found delay times ranging from 80 to 1100 microseconds and for methylcyclohexane were found delay times ranging from 150 to 1100 microseconds. For tests with equivalence ratio 2 at 1.5 atm were found for methyl octanoate ignition delay times ranging from 100 to 900 microseconds, for n-nonane and for methylcyclohexane were found delay times ranging from 100 to 1100 microseconds. For tests with equivalence ratio 2 at 10 atm were found for methyl octanoate and methylcyclohexane ignition delay times ranging from 90 to 1000 microseconds, for n-nonane were found delay times ranging from 100 to 1100 microseconds. [12] also conducted shock tube tests with methyl stearate, methyl oleate, methyl linoleate, methyl linolenate, and methyl palmitate and were found ignition delay times for all fuel testing ranging from 200 to 90000 microseconds for testing at 13.5 bar. The tests were performed at temperatures from 700 to 1100 K and equivalence ratio 1. [13] also conducted shock tube tests with jets fuels, rocket propellants, diesel fuel and gasoline fuel and were found ignition delay times for all fuel testing ranging from 100 to 1900 microseconds for testing at pressure from 6 to 60 atm. The tests were performed at temperatures from 1000 to 1400 K and equivalence ratio 0.85 and 1.15. [14] also conducted shock tube tests with mixture of biodiesel with diesel fuel and were found ignition delay times for all fuel testing ranging from 60 to 2600 microseconds for testing at pressure at 0.12 Mpa. The tests were performed at temperatures from 1174 to 1685 K and equivalence ratio 0.5, 1 and 1.5. [15] also conducted shock tube tests with diesel fuel and alternative hydro processed jet fuels. The tests were performed at temperatures from 650 to 1300 K, pressures from 0.8 to 80 atm and equivalence ratio 0.25 to 1.5. For testing with jet fuels were found ignition delay times ranging from 60 to 8000 microseconds and for testing with diesel fuels were found ignition delay times ranging from 90 to

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

**76**

4000 microseconds. [16] also conducted shock tube tests with conventional and alternative jet fuels, alcohol to jet, direct sugar to hydrocarbon, biodiesel-like fuel, n-heptane, n-dodecane, m-xylene and iso-dodecane. Were found ignition delay times for all fuel testing ranging from 20 to 3200 microseconds. The tests were performed at temperatures from 980 to 1800 K, pressures at 16 atm and equivalence ratio at 0.5.

#### **4. Experimental measuring the ignition delay times of the convectional diesel and biodiesel from soybean oil using a shock tube**

The experiments were conducted in the heated shock tube facility of the Mobility Technology Center (CTM) of Federal University of Minas Gerais (UFMG). The shock tube has a 3 m long driver section and a 3 m long driven section with an internal diameter of 97.20 mm. Aluminum diaphragm of 0.4 mm thickness divided the driver and driven sections before each experiment. The experiments were carried out with convectional Diesel and pure biodiesel from soy oil. The convectional Diesel used in this study is normally fuel found at gas stations and it has a cetane number of 43. The pure biodiesel used in this study was derived from a process of refining oil from soy oil and it has a cetane number of 38. The instrumentation within the shock tube used for the experiment included three pressure sensors (P1, P2 and P3), two temperature sensors (T3 and T1), a luminosity detection sensor (L1) and a fuel injector (FI). In the present work a mixture of the Nitrogen (N2) and Argon (Ar) gases was used as the driver gas to obtain a longer test time. The **Figure 7** shows the position of the sensors, fuel injector, aluminum diaphragm location and mixture of the Nitrogen and Argon inlet in the shock tube.

The pressure sensor P3 (located at 1700 mm before the aluminum diaphragm) was used to monitor the pressure in the driver section and the diaphragm rupture pressure. The pressure sensor P2 (located at 700 mm after the aluminum diaphragm) was used to indicates the moment of passage of the shock wave after diaphragm rupture. This information is used to control and define the fuel injection timing. The pressure sensor P1 (located at 2700 mm after the diaphragm) was used to indicates the moment of passage of shock in region 1 where combustion occurs. For monitor the temperature in the driver section was used an analog temperature sensor T3. For monitor and control the temperature in the driven section was used a temperature sensor T1 with the same characteristics that the temperature sensor T3 used in driver section. The luminosity detection sensor L1 was used to indicates the

#### **Figure 7.**

*Position of the sensors, fuel injector, aluminum diaphragm location and mixture of the nitrogen and argon inlet in the shock tube (adapted from [17]).*

moment of combustion. At the moment of ignition, the voltage of this sensor decreases in function of flame in shock tube. This information together with the pressure signal of P1 sensor was used to calculated the ignition delay time. The fuel injector FI injects fuel into the shock tube when the sensor pressure P2 detects the

passage of shock wave. The ignition delay time was calculated by the time difference between the passage of the shock wave by the P1 sensor and the start of the ignition detected by the luminosity detection sensor L1. The **Figure 8** shows a result of calculation of the ignition delay time of diesel measured in shock tube in air at shock reflected pressure of 24.2 bar, equivalence ratio of 1 and temperature of

The **Table 1** listed the measured ignition delay time τ for convectional diesel. All

**Incident shock Reflected shock Ignition delay time**

measurements were carried out equivalence ratios 1. The experiments were performed in the temperature range of 903 to 1260 K and target pressures were approximately 24 bar. Were found ignition delay times ranging from 316 to 856

**P2 (bar) T2 (K) P5 (bar) T5 (K) τ (μs)** 14.6 942 24.7 1125 1356 14 918 24.4 960 1636 14.1 965 24.2 1150 945 13.2 932 23.6 995 1635 14.7 885 24.1 940 1525 14.3 948 24.5 1060 1567 13.9 935 23.2 1095 1470 13.4 842 24.7 916 1782 13.7 880 24.5 926 1678 14.7 982 24.8 1210 640 14.8 947 24.7 1180 982

*Measured ignition delay times for pure biodiesel from soybean oil in air (adapted from [17]).*

*Ignition delay times for diesel and biodiesel from soybean oil in present study (adapted from [17]).*

1260 K.

**Table 2.**

**Figure 9.**

**79**

microseconds.

*Shock Tube Combustion Analysis*

*DOI: http://dx.doi.org/10.5772/intechopen.96870*

#### **Figure 8.**

*Ignition delay time of diesel in air at shock reflected pressure of 24.2 bar, equivalence ratio of 1 and temperature of 1260 K (adapted from [17]).*


**Table 1.** *Measured ignition delay times for convectional diesel in air (adapted from [17]).*

#### *Shock Tube Combustion Analysis DOI: http://dx.doi.org/10.5772/intechopen.96870*

passage of shock wave. The ignition delay time was calculated by the time difference between the passage of the shock wave by the P1 sensor and the start of the ignition detected by the luminosity detection sensor L1. The **Figure 8** shows a result of calculation of the ignition delay time of diesel measured in shock tube in air at shock reflected pressure of 24.2 bar, equivalence ratio of 1 and temperature of 1260 K.

The **Table 1** listed the measured ignition delay time τ for convectional diesel. All measurements were carried out equivalence ratios 1. The experiments were performed in the temperature range of 903 to 1260 K and target pressures were approximately 24 bar. Were found ignition delay times ranging from 316 to 856 microseconds.


**Table 2.**

moment of combustion. At the moment of ignition, the voltage of this sensor decreases in function of flame in shock tube. This information together with the pressure signal of P1 sensor was used to calculated the ignition delay time. The fuel injector FI injects fuel into the shock tube when the sensor pressure P2 detects the

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

*Ignition delay time of diesel in air at shock reflected pressure of 24.2 bar, equivalence ratio of 1 and temperature*

**P2 (bar) T2 (K) P5 (bar) T5 (K) τ (μs)** 14.2 932 24.6 1150 362 14.2 945 24.3 1162 342 14 962 24.2 1260 329 13.7 874 23.6 940 603 14.2 912 23.8 1065 316 14.1 918 24.6 1082 418 13.9 915 23.1 980 443 13.4 902 24.2 1008 439 13.2 874 24.7 972 518 13.9 862 24.3 965 780 13.6 854 24.7 903 856 14 862 24.1 920 790 14.2 840 24.2 972 680 13.9 798 24.8 995 648 13.8 823 24.5 1040 490 13.6 890 23.8 1120 412 14 944 23.9 1243 325

*Measured ignition delay times for convectional diesel in air (adapted from [17]).*

**Incident shock Reflected shock Ignition delay time**

**Figure 8.**

**Table 1.**

**78**

*of 1260 K (adapted from [17]).*

*Measured ignition delay times for pure biodiesel from soybean oil in air (adapted from [17]).*

**Figure 9.** *Ignition delay times for diesel and biodiesel from soybean oil in present study (adapted from [17]).*

The **Table 2** listed the measured ignition delay time τ for pure biodiesel from soybean. All measurements were carried out equivalence ratios 1. The experiments were performed in the temperature range of 916 to 1210 K and target pressures were approximately 24 bar. Were found ignition delay times ranging from 640 to 1782 microseconds.

**References**

pecs.2017.09.004.

107883156.

06.180.

[1] Sarathy, S. M., Farooq, A. and Kalghatgib, G. T., **Recent progress in gasoline surrogate fuels,** Progress in Energy and Combustion Science 65 (2018) 67–108, doi.org/10.1016/j.

*DOI: http://dx.doi.org/10.5772/intechopen.96870*

*Shock Tube Combustion Analysis*

**oxidation: Ignition delay times and time-histories of multiple species and temperature,** Proceedings of the Comb ustion Institute 35 (2015) 231–239. doi:

[9] K. Y. Lam, Z. Hong, D. F. Davison, R. K. Hanson, **Shock tube ignition delay time measurements in propane / O2 / argon mixtures at near-constantvolume conditions,** Proceeding of the Combustion Institute 33 (2011) 251–258.

[10] S. M. Walton, D. M. Karwat, P. D. Teini, A. M. Gorny, M. S. Wooldridge,

[11] B. Rotavera, E.L. Petersen, **Ignition behavior of pure and blended methyl**

**methylcyclohexane,** Proceeding of the Combustion Institute 34 (2013) 435–

[12] C. K. Westbrook, C. V. Naikb, O. Herbinetc, W. J. Pitza, M. Mehla, S. M. Sarathya, H. J. Currand, **Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels,** Combustion and Flame 158 (2011) 742– 755, doi: 10.1016/j.combustflame.2010.

[13] D.F. Davidson, Y. Zhu, J. Shao, R.K.

**correlations for distillate fuels,** Fuel 187 (2017) 26–32. doi.org/10.1016/j.fuel.

**Experimental study of the ignition delay of diesel and biodiesel blends using a shock tube,** Biosystems engineering 134 (2015) 1–7. doi.org/ 10.1016/j.biosystemseng.2015.03.009.

[15] S. Gowdagiri, M. A. Oehlschlaeger,

**Conventional and Alternative Jet and**

Hanson, **Ignition delay time**

[14] V. N. Hoang, L. D. Thi,

**Global Reduced Model for**

**Speciation studies of methyl butanoate ignition,** Fuel 90 (2011)

**octanoate, n-nonane and**

1796–1804.

442.

10.020.

2016.09.047.

10.1016/j.proci.2014.05.001.

[2] Glass, I. I., **Shock Tubes**: Part I. Toronto: University of Toronto, 1958.

[4] H. J. Gordon, **Shock Tubes**: Part II. Toronto: University of Toronto, 1958.

[5] L. R. Cancino, M. Fikri, A. A. M. Oliveira, C. Shulz, **Autoignition of gasoline surrogate mixtures at intermediate temperatures and high**

**numerical approaches**, Proceeding of the Combustion institute, 32 (2009) 501–508, doi:10.1016/j.proci.2008.

[6] S. Niu, J. Zhang, Y. Zhang, C. Tang,

**Experimental and modeling study of the auto-ignition of n-heptane and nbutanol mixtures,** Combustion and Flame 160 (2013) 31–39, doi:10.1016/j.

[7] M. Fikri, J. Herzler, R. Starke, C. Schulz, P. Roth, G. T. Kalghatgi, **Autoignition of gasoline surrogates'**

**temperatures and high pressures**, Combustion and Flame 152 (2008) 276– 281. doi:10.1016/j.combustflame.

[8] M. F. Campbell, S. Wang, C. S. Goldenstein, R. M. Spearrin, A. M. Tulgestke, L. T. Zaczek, D. F. Davidson, R. K. Hanson, **Constrained reaction volume shock tube study of** *n***-heptane**

**pressures: Experimental and**

X. Jiang, E. Hu, Z. Huang,

combustflame.2012.09.006.

**mixtures at intermediate**

2007.07.010.

**81**

[3] Mcmillan, R.J. **Shock tube investigation of pressure and ion sensors used in pulse detonation engine research,** (2012), Corpus ID:

The **Figure 9** compare the ignition delay times for diesel and biodiesel from soybean oil measured in present study.

The ignition delay times measured in this study are consistent with those found in the literature. For convectional Diesel fuel were found times ranging from 316 to 856 microseconds and for biodiesel from soybean oil fuel were found times ranging from 640 to 1782 microseconds. These measured values are consistent with expectations since convectional Diesel has a higher cetane number than biodiesel from soybean oil. Convectional Diesel have a cetane number 43 while biodiesel from soybean oil have cetane number 38. This study confirm that the ignition delay time decreases with increasing cetane number. Fuel with a high cetane number has a short ignition delay time and the best quality in the combustion process.

#### **Author details**

Claudio Marcio Santana<sup>1</sup> and Jose Eduardo Mautone Barros<sup>2</sup> \*


\*Address all correspondence to: mautone@demec.ufmg.br

© 2021 The Author(s). Licensee IntechOpen. This chapter is 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.

*Shock Tube Combustion Analysis DOI: http://dx.doi.org/10.5772/intechopen.96870*

#### **References**

The **Table 2** listed the measured ignition delay time τ for pure biodiesel from soybean. All measurements were carried out equivalence ratios 1. The experiments were performed in the temperature range of 916 to 1210 K and target pressures were approximately 24 bar. Were found ignition delay times ranging from 640 to

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

The **Figure 9** compare the ignition delay times for diesel and biodiesel from

The ignition delay times measured in this study are consistent with those found in the literature. For convectional Diesel fuel were found times ranging from 316 to 856 microseconds and for biodiesel from soybean oil fuel were found times ranging from 640 to 1782 microseconds. These measured values are consistent with expectations since convectional Diesel has a higher cetane number than biodiesel from soybean oil. Convectional Diesel have a cetane number 43 while biodiesel from soybean oil have cetane number 38. This study confirm that the ignition delay time decreases with increasing cetane number. Fuel with a high cetane number has a short ignition delay time and the best quality in the combustion process.

1782 microseconds.

**Author details**

**80**

Claudio Marcio Santana<sup>1</sup> and Jose Eduardo Mautone Barros<sup>2</sup>

2 University Federal of Minas Gerais, Belo Horizonte, Brazil

\*Address all correspondence to: mautone@demec.ufmg.br

provided the original work is properly cited.

© 2021 The Author(s). Licensee IntechOpen. This chapter is 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,

1 Federal University of Ouro Preto, Ouro Preto, Brazil

\*

soybean oil measured in present study.

[1] Sarathy, S. M., Farooq, A. and Kalghatgib, G. T., **Recent progress in gasoline surrogate fuels,** Progress in Energy and Combustion Science 65 (2018) 67–108, doi.org/10.1016/j. pecs.2017.09.004.

[2] Glass, I. I., **Shock Tubes**: Part I. Toronto: University of Toronto, 1958.

[3] Mcmillan, R.J. **Shock tube investigation of pressure and ion sensors used in pulse detonation engine research,** (2012), Corpus ID: 107883156.

[4] H. J. Gordon, **Shock Tubes**: Part II. Toronto: University of Toronto, 1958.

[5] L. R. Cancino, M. Fikri, A. A. M. Oliveira, C. Shulz, **Autoignition of gasoline surrogate mixtures at intermediate temperatures and high pressures: Experimental and numerical approaches**, Proceeding of the Combustion institute, 32 (2009) 501–508, doi:10.1016/j.proci.2008. 06.180.

[6] S. Niu, J. Zhang, Y. Zhang, C. Tang, X. Jiang, E. Hu, Z. Huang, **Experimental and modeling study of the auto-ignition of n-heptane and nbutanol mixtures,** Combustion and Flame 160 (2013) 31–39, doi:10.1016/j. combustflame.2012.09.006.

[7] M. Fikri, J. Herzler, R. Starke, C. Schulz, P. Roth, G. T. Kalghatgi, **Autoignition of gasoline surrogates' mixtures at intermediate temperatures and high pressures**, Combustion and Flame 152 (2008) 276– 281. doi:10.1016/j.combustflame. 2007.07.010.

[8] M. F. Campbell, S. Wang, C. S. Goldenstein, R. M. Spearrin, A. M. Tulgestke, L. T. Zaczek, D. F. Davidson, R. K. Hanson, **Constrained reaction volume shock tube study of** *n***-heptane** **oxidation: Ignition delay times and time-histories of multiple species and temperature,** Proceedings of the Comb ustion Institute 35 (2015) 231–239. doi: 10.1016/j.proci.2014.05.001.

[9] K. Y. Lam, Z. Hong, D. F. Davison, R. K. Hanson, **Shock tube ignition delay time measurements in propane / O2 / argon mixtures at near-constantvolume conditions,** Proceeding of the Combustion Institute 33 (2011) 251–258.

[10] S. M. Walton, D. M. Karwat, P. D. Teini, A. M. Gorny, M. S. Wooldridge, **Speciation studies of methyl butanoate ignition,** Fuel 90 (2011) 1796–1804.

[11] B. Rotavera, E.L. Petersen, **Ignition behavior of pure and blended methyl octanoate, n-nonane and methylcyclohexane,** Proceeding of the Combustion Institute 34 (2013) 435– 442.

[12] C. K. Westbrook, C. V. Naikb, O. Herbinetc, W. J. Pitza, M. Mehla, S. M. Sarathya, H. J. Currand, **Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels,** Combustion and Flame 158 (2011) 742– 755, doi: 10.1016/j.combustflame.2010. 10.020.

[13] D.F. Davidson, Y. Zhu, J. Shao, R.K. Hanson, **Ignition delay time correlations for distillate fuels,** Fuel 187 (2017) 26–32. doi.org/10.1016/j.fuel. 2016.09.047.

[14] V. N. Hoang, L. D. Thi, **Experimental study of the ignition delay of diesel and biodiesel blends using a shock tube,** Biosystems engineering 134 (2015) 1–7. doi.org/ 10.1016/j.biosystemseng.2015.03.009.

[15] S. Gowdagiri, M. A. Oehlschlaeger, **Global Reduced Model for Conventional and Alternative Jet and** **Diesel Fuel Autoignition,** Energy Fuels 28 (2014) 2795–2801. doi.org/10.1021/ ef500346m.

[16] G. Flora, J. Balagurunathan, S. Saxena, J. P. Cain, M. S. P. Kahandawala, M. J. DeWitt, S. S. Sidhua, E. Corporan, **Chemical ignition delay of candidate drop-in replacement jet fuels under fuel-lean conditions: A shock tube study,** Fuel 209 (2017) 457–472. doi.org/10.1016/ j.fuel.2017.07.082.

[17] Santana, C.S., Barros, J. E. M., Junior, H. A. A, Braga, J. O. and Neto, J. C. B, **Measuring and comparing the ignition delay time of the reference diesel, convectional diesel, additive ethanol and biodiesel from soybean oil using a shock tube**, Journal of the Brazilian Society of Mechanical Sciences and Engineering (2020) 42:102, doi: 10.1007/s40430-020-2183-z.

**83**

**Chapter 5**

**Abstract**

**1. Introduction**

Assessing the Effects of Engine

Load on Compression Ignition

Engines Using Biodiesel Blends

This study evaluated the performance of a diesel engine operated with waste plastic biodiesel fuel (WPPO) blends. Findings were that at all engine loads (from idling to full load) the emissions of carbon monoxide (CO), unburnt hydrocarbon (UHC) and carbon dioxide (CO2) were low compared to conventional diesel (PD), although the emissions of NOX were higher. The brake specific fuel consumption (BSFC) for the blends dropped while the brake thermal efficiency (BTE) increased with load for all blends until intermediate load when it decreased. WPPO blends had a higher viscosity compared to PD. CO emissions for blend 95/WPPO5 at all engine speed idling modes were 285 ppm, 298 ppm, 320ppm, and 388 ppm while PD emissions were 270 ppm, 295 ppm, 315 ppm and 365 ppm respectively. The values for UHC for blend 95/WPPO5 at all modes were 35 ppm, 28 ppm, 22 ppm, and 18 ppm compared to PD fuel with 20ppm, 25 ppm, 30 ppm, and 40ppm respectively. The NOX emissions for PD fuel at all modes were 175 ppm, 225 ppm, 300 ppm and 375 ppm compared to blend 95/WPPO5 at 195 ppm, 245 ppm, 335 ppm, and 397 ppm. The BSFC values for blend 95/WPPO5 at all modes were 0.48 kg/kW.h, 0.41 kg/kW.h, 0.35 kg/kW.h and 0.4 kg/kW.h compared to PD at 0.45 kg/kW.h,

*Semakula Maroa and Freddie Inambao*

0.39 kg/kW.h, 0.33 kg/kW.h and 035 kg/kW.h respectively.

able while meeting a large energy demand [8].

**Keywords:** engine loads, emissions, higher viscosity, spray characteristics

Development of alternative fuel energy began in the 1900s when German engineer Rudolf Diesel invented the diesel engine using vegetable oil [1]. However, due to availability of petroleum at the time the focus moved into fossil fuel to the disadvantage of bio-oil. Currently many researchers such as [2–7] have focused on development of alternative fuel to petro-diesel (PD). Most of this research is heavily biodiesel based as this is one of the solutions to replace fossil fuels while creating renewable and green fuels. Fossil fuels are non-renewable and are depleting rapidly, hence the need for large-scale research to find alternative and renewable fuels. Alternative fuels must prove to be feasible, environmentally friendly and sustain-

Fossil fuels have a detrimental environmental impact [9] when released to the atmosphere due to the combustion activities of fossil fuels. It is being projected that if no measures are put in place by 2030 the use of fossil fuel will raise emission levels by 39% [10]. Besides environmental concerns, fossil fuels have erratic demand and

#### **Chapter 5**

**Diesel Fuel Autoignition,** Energy Fuels 28 (2014) 2795–2801. doi.org/10.1021/

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

[16] G. Flora, J. Balagurunathan, S.

**replacement jet fuels under fuel-lean conditions: A shock tube study,** Fuel 209 (2017) 457–472. doi.org/10.1016/

[17] Santana, C.S., Barros, J. E. M., Junior, H. A. A, Braga, J. O. and Neto, J. C. B, **Measuring and comparing the ignition delay time of the reference diesel, convectional diesel, additive ethanol and biodiesel from soybean oil using a shock tube**, Journal of the Brazilian Society of Mechanical Sciences and Engineering (2020) 42:102, doi: 10.1007/s40430-020-2183-z.

Saxena, J. P. Cain, M. S. P. Kahandawala, M. J. DeWitt, S. S. Sidhua, E. Corporan, **Chemical ignition**

**delay of candidate drop-in**

j.fuel.2017.07.082.

**82**

ef500346m.

## Assessing the Effects of Engine Load on Compression Ignition Engines Using Biodiesel Blends

*Semakula Maroa and Freddie Inambao*

#### **Abstract**

This study evaluated the performance of a diesel engine operated with waste plastic biodiesel fuel (WPPO) blends. Findings were that at all engine loads (from idling to full load) the emissions of carbon monoxide (CO), unburnt hydrocarbon (UHC) and carbon dioxide (CO2) were low compared to conventional diesel (PD), although the emissions of NOX were higher. The brake specific fuel consumption (BSFC) for the blends dropped while the brake thermal efficiency (BTE) increased with load for all blends until intermediate load when it decreased. WPPO blends had a higher viscosity compared to PD. CO emissions for blend 95/WPPO5 at all engine speed idling modes were 285 ppm, 298 ppm, 320ppm, and 388 ppm while PD emissions were 270 ppm, 295 ppm, 315 ppm and 365 ppm respectively. The values for UHC for blend 95/WPPO5 at all modes were 35 ppm, 28 ppm, 22 ppm, and 18 ppm compared to PD fuel with 20ppm, 25 ppm, 30 ppm, and 40ppm respectively. The NOX emissions for PD fuel at all modes were 175 ppm, 225 ppm, 300 ppm and 375 ppm compared to blend 95/WPPO5 at 195 ppm, 245 ppm, 335 ppm, and 397 ppm. The BSFC values for blend 95/WPPO5 at all modes were 0.48 kg/kW.h, 0.41 kg/kW.h, 0.35 kg/kW.h and 0.4 kg/kW.h compared to PD at 0.45 kg/kW.h, 0.39 kg/kW.h, 0.33 kg/kW.h and 035 kg/kW.h respectively.

**Keywords:** engine loads, emissions, higher viscosity, spray characteristics

#### **1. Introduction**

Development of alternative fuel energy began in the 1900s when German engineer Rudolf Diesel invented the diesel engine using vegetable oil [1]. However, due to availability of petroleum at the time the focus moved into fossil fuel to the disadvantage of bio-oil. Currently many researchers such as [2–7] have focused on development of alternative fuel to petro-diesel (PD). Most of this research is heavily biodiesel based as this is one of the solutions to replace fossil fuels while creating renewable and green fuels. Fossil fuels are non-renewable and are depleting rapidly, hence the need for large-scale research to find alternative and renewable fuels. Alternative fuels must prove to be feasible, environmentally friendly and sustainable while meeting a large energy demand [8].

Fossil fuels have a detrimental environmental impact [9] when released to the atmosphere due to the combustion activities of fossil fuels. It is being projected that if no measures are put in place by 2030 the use of fossil fuel will raise emission levels by 39% [10]. Besides environmental concerns, fossil fuels have erratic demand and

supply which increases international market prices and other commodities hence promoting inflation [11]. **Figure 1** shows measures taken as a way of combating environmental pollution from the transportation industry in the European Union by means of taxes and social contribution as a function of gross domestic product.

In order to determine the efficacy of biodiesel, mainstream researchers in biodiesel fuels have evaluated engine performance using different feedstocks and different biodiesel blends [13–16]. However, few have been able to investigate the influence of load using plastic waste oil blends of biodiesel [17–19]. All these researchers have concentrated on performance and emission characteristics with little attention to low load and intermediate load compared to engine full load [8, 20, 21]. For example, all low load and intermediate engine idling speeds are considered as high idling, and mostly increase emissions from trucks and vehicles in the transport industry.

High idling or low engine loads have been shown to increase NOX emissions on roads compared to high speed road driving by a factor of 1.5 [22, 23]. In other words, increasing low load increases NOX emissions [24–26]. During idling, which is low load, the fuel consumption as well as engine wear and maintenance increase. The average fuel consumption for example in trucks at idle is 0.8 g/hr. to 1.5 g/hr. based on the size of the engine, ambient temperature and the load of other systems such as HVAC and vehicle electrical loads [27]. This is when compared to driving cycle emissions of UHC that are 1–5 times more.

On the other hand, during low load other emissions such as CO rise to 295 g/hr. [28–30]. The carbon emissions during the driving cycles are estimated at 45–75%, while UHC emissions during idling and low load can reach 86.4 g/hr. [27, 31]. Most diesel engines typically spend a substantial amount of time in idling mode, either at traffic stops, checkpoints or in exchange periods in fuel stations. The idle time spent varies considerably with the many varied reasons for maintaining engines at idle. For long haulage trucks, for example, the most common reason is climate control, loading and offloading transport cargo or service and maintenance [32, 33]. The other reason why trucks idle for a long time is use of the engines to heat and air-condition cabs and to power amenities in the cab while on the road [34, 35].

**85**

liters.

*Assessing the Effects of Engine Load on Compression Ignition Engines Using Biodiesel Blends*

engine modification which gives it high technical advantage [41, 42].

The use of biodiesel and biodiesel blends affect diesel engine performance characteristics. Poor quality biodiesel fuel results in deposits and clogging [43, 44]. Besides these problems, use of biodiesel can result in corrosion, excessive engine wear and premature engine failure [45]. Biodiesel also causes deposits in the injector pump, which interferes with the spray pattern, an essential factor in mixing fuel during the combustion process, hence poor engine performance [46]. Other demerits, which are associated with biodiesel fuel use, include dilution of lubrication oil leading to high crank-case oil levels followed by loss of engine oil pressure and increased engine bearing wear. Thus, it is clear that the quality and testing of biodiesel is an important factor in ensuring proper rating, acceptance and durability

The objective of this work was to use waste plastic pyrolysis oil (WPPO) and determine the effects of idling speed load-using blends of WPPO on a diesel engine. The second objective was to study the effect of brake specific fuel consumption (BSFC) of WPPO at low and intermediate engine conditions, also known as high idling condition. The third objective was to find the effect of engine load at high idling on engine performance and emission characteristics using WPPO as an

WPPO was selected for this study because of the advantage of turning waste into energy to reduce the environmental impact of waste plastic. The second factor that informed the use of waste plastic is sustainability as waste plastic is readily available in municipal solid waste management sites. The plastics were collected from various holding facilities within the Durban metropolitan centres comprising a variety of

The pyrolysis oil was obtained from the pyrolysis unit in the Green Energy Group laboratory in the Department of Mechanical Engineering, University of KwaZulu-Natal. The author in his previous work covered the design of the unit and its performance analysis was published in the proceedings of the DUE 2019 conference in Cape Town [47]. The WPPO testing and measurements were conducted at InterTek, a private laboratory in Durban and the results are shown in **Table 1**.

A two-step process was used to process the WPPO as its acid value is higher compared to petroleum diesel. Therefore, an acid catalyzed process was used with the molar ratio maintained at 12: (50% v. v), 1% of H2SO4 was added to the preheated oil at 70°C for 3.5 hrs with a stirring speed of 400 r/min in a reactor of 5

Biodiesel oil is known to contain physicochemical characteristics of functional PD properties [36, 37]. Research has shown biodiesel fuels have many advantages over PD. For example, biodiesels are biodegradable, non-flammable, renewable, non-explosive, non-toxic and environmentally friendly [38, 39]. These qualities show biodiesel fuels to be the best options to substitute for fossil fuels. Biodiesel fuels have a variety of feedstocks such as used vegetable oil, waste plastics, waste biomass, animal fats (tallow) and recently microalgae, all which can be processed into biodiesel [40]. Biodiesel has the ability to be utilized as a fuel with or without

*DOI: http://dx.doi.org/10.5772/intechopen.95974*

of diesel engines.

alternative fuel.

plastics.

**2. Methodology and materials**

**2.1 Crude WPPO oil properties**

**2.2 WPPO biodiesel processing**

#### **Figure 1.**

*Environmental taxes as % of GDP and as % of total taxes and social contributions [12].*

#### *Assessing the Effects of Engine Load on Compression Ignition Engines Using Biodiesel Blends DOI: http://dx.doi.org/10.5772/intechopen.95974*

Biodiesel oil is known to contain physicochemical characteristics of functional PD properties [36, 37]. Research has shown biodiesel fuels have many advantages over PD. For example, biodiesels are biodegradable, non-flammable, renewable, non-explosive, non-toxic and environmentally friendly [38, 39]. These qualities show biodiesel fuels to be the best options to substitute for fossil fuels. Biodiesel fuels have a variety of feedstocks such as used vegetable oil, waste plastics, waste biomass, animal fats (tallow) and recently microalgae, all which can be processed into biodiesel [40]. Biodiesel has the ability to be utilized as a fuel with or without engine modification which gives it high technical advantage [41, 42].

The use of biodiesel and biodiesel blends affect diesel engine performance characteristics. Poor quality biodiesel fuel results in deposits and clogging [43, 44]. Besides these problems, use of biodiesel can result in corrosion, excessive engine wear and premature engine failure [45]. Biodiesel also causes deposits in the injector pump, which interferes with the spray pattern, an essential factor in mixing fuel during the combustion process, hence poor engine performance [46]. Other demerits, which are associated with biodiesel fuel use, include dilution of lubrication oil leading to high crank-case oil levels followed by loss of engine oil pressure and increased engine bearing wear. Thus, it is clear that the quality and testing of biodiesel is an important factor in ensuring proper rating, acceptance and durability of diesel engines.

The objective of this work was to use waste plastic pyrolysis oil (WPPO) and determine the effects of idling speed load-using blends of WPPO on a diesel engine. The second objective was to study the effect of brake specific fuel consumption (BSFC) of WPPO at low and intermediate engine conditions, also known as high idling condition. The third objective was to find the effect of engine load at high idling on engine performance and emission characteristics using WPPO as an alternative fuel.

#### **2. Methodology and materials**

#### **2.1 Crude WPPO oil properties**

WPPO was selected for this study because of the advantage of turning waste into energy to reduce the environmental impact of waste plastic. The second factor that informed the use of waste plastic is sustainability as waste plastic is readily available in municipal solid waste management sites. The plastics were collected from various holding facilities within the Durban metropolitan centres comprising a variety of plastics.

The pyrolysis oil was obtained from the pyrolysis unit in the Green Energy Group laboratory in the Department of Mechanical Engineering, University of KwaZulu-Natal. The author in his previous work covered the design of the unit and its performance analysis was published in the proceedings of the DUE 2019 conference in Cape Town [47]. The WPPO testing and measurements were conducted at InterTek, a private laboratory in Durban and the results are shown in **Table 1**.

#### **2.2 WPPO biodiesel processing**

A two-step process was used to process the WPPO as its acid value is higher compared to petroleum diesel. Therefore, an acid catalyzed process was used with the molar ratio maintained at 12: (50% v. v), 1% of H2SO4 was added to the preheated oil at 70°C for 3.5 hrs with a stirring speed of 400 r/min in a reactor of 5 liters.

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

in the transport industry.

the road [34, 35].

cycle emissions of UHC that are 1–5 times more.

*Environmental taxes as % of GDP and as % of total taxes and social contributions [12].*

supply which increases international market prices and other commodities hence promoting inflation [11]. **Figure 1** shows measures taken as a way of combating environmental pollution from the transportation industry in the European Union by means of taxes and social contribution as a function of gross domestic product. In order to determine the efficacy of biodiesel, mainstream researchers in biodiesel fuels have evaluated engine performance using different feedstocks and different biodiesel blends [13–16]. However, few have been able to investigate the influence of load using plastic waste oil blends of biodiesel [17–19]. All these researchers have concentrated on performance and emission characteristics with little attention to low load and intermediate load compared to engine full load [8, 20, 21]. For example, all low load and intermediate engine idling speeds are considered as high idling, and mostly increase emissions from trucks and vehicles

High idling or low engine loads have been shown to increase NOX emissions on roads compared to high speed road driving by a factor of 1.5 [22, 23]. In other words, increasing low load increases NOX emissions [24–26]. During idling, which is low load, the fuel consumption as well as engine wear and maintenance increase. The average fuel consumption for example in trucks at idle is 0.8 g/hr. to 1.5 g/hr. based on the size of the engine, ambient temperature and the load of other systems such as HVAC and vehicle electrical loads [27]. This is when compared to driving

On the other hand, during low load other emissions such as CO rise to 295 g/hr. [28–30]. The carbon emissions during the driving cycles are estimated at 45–75%, while UHC emissions during idling and low load can reach 86.4 g/hr. [27, 31]. Most diesel engines typically spend a substantial amount of time in idling mode, either at traffic stops, checkpoints or in exchange periods in fuel stations. The idle time spent varies considerably with the many varied reasons for maintaining engines at idle. For long haulage trucks, for example, the most common reason is climate control, loading and offloading transport cargo or service and maintenance [32, 33]. The other reason why trucks idle for a long time is use of the engines to heat and air-condition cabs and to power amenities in the cab while on

**84**

**Figure 1.**

#### *Internal Combustion Engine Technology and Applications of Biodiesel Fuel*


**Table 1.**

*Properties of diesel and WPPO before processing into biodiesel properties.*

Thereafter the products were put into a separating funnel and the excess alcohol, sulfuric acid and other impurities in the upper layer were drained.

To remove methanol and water from the esterified oil a rotary evaporator was employed at 100°C under vacuum for 1 hour and 20minutes.

To complete the process reaction an alkaline catalyzed process was employed by reacting the esterified oil with methanol at 6:1 molar ratio and 1% potassium hydroxide (KOH) at 80°C for 2 hours and a stirring speed of 400 r/min.

The final step to obtain a refined biodiesel oil was to leave the produced biodiesel in a separation funnel overnight, for the reaction to end. This process required 12 hours to finish reacting before the lower layer of impurities can be discarded.

#### **2.3 WPPO fatty acid composition**

The fatty acid for a double bond is unsaturated, so a single bond fatty acid, which is saturated, was tested using the FT-IR and confirmed by the GC–MS method. **Table 2** shows the GC–MS operating conditions while **Table 3** shows the FT-IR indicated compounds of pyrolysis biodiesel oil and their class of compound.

The biodiesel obtained was composed of more than 20 compounds of mixed proportion whose composition and GC–MS percentage areas spectrum are presented in **Table 4**. **Table 5** has a list of test equipment utilized in the experiment.

Considering percentage areas of the spectrum, the highest pick areas of the total chromatography were the following: heptadecane, n-octadecane, n-hexadecane, nonadecane, pentadecane, eicosane, tetradecane and tridecane. Eq. 1 shows the effect of linear velocity of the carrier gas in retention time which was used to determine the carrier gas linear velocity.

$$t\_r = L \frac{\left(K + 1\right)}{\mu} \tag{1}$$

**87**

**Table 4.**

*Elemental fatty acid composition of WPPO.*

**Table 2.**

**Table 3.**

*Assessing the Effects of Engine Load on Compression Ignition Engines Using Biodiesel Blends*

Injector Split injector, 50:1ratio, 0.3 μL injection volume

Temperature ramp 1 100°C zero minutes hold Temperature ramp 2 10 °C/min to 250°C 5 minutes hold

Detector temperature 250°C Column head pressure 23.8

**Frequency range (cm−1) Group Class compound**

3150–2950 C-H stretching Alkanes

1830–1725 C ≡ C stretching alkenes

1575–1475 C-H bending alkanes

1175–1150 C-H bending alkanes 1000–950 C ≡ C stretching alkynes

*FT-IR WPPO indicated compounds of pyrolysis biodiesel oil.*

3750–3250 O-H stretching Polymeric O-H, HO2 impurities

1725–1575 -NO2 stretching Nitrogenous compounds

1475–1375 C-O stretching Primary/secondary alcohols 1325–1200 O-H bending Esters, ethers, phenols

900–875 — Aromatic compounds

**Composition Chemical name Percentage** C10 Aliphatic compounds 65 C10-C13 Doxosane 2.4 C13-C16 Isoparaffin 7.5 C16 - C20 1-hexadecene 3.1 C20 – C23 Eicosane 7.6 C23-C30 Docosane 15.4 C 81.5 H 11.3 O 7.2

1950–1830 C=O stretching Ketones, aldehydes, carboxylic acid

H2 = 40 ml/min He = 20 ml/min

**Property Specification** Carrier gas Helium @ 23.8 psi Linear velocity 44 cm/s@100°C Flow rate Air = 450 ml/min

*DOI: http://dx.doi.org/10.5772/intechopen.95974*

*Showing GC–MS operating conditions during the experiment.*

Where.

tr is the retention time.

L is the column height.

K is the retention factor (constant).

μ is the carrier gas linear velocity.

The components present in mixed WPPO range from carbon number C10 to C40. A large percentage of these components are made of aliphatic compounds as shown by the result the GC–MS spectrum result in **Table 4**.

*Assessing the Effects of Engine Load on Compression Ignition Engines Using Biodiesel Blends DOI: http://dx.doi.org/10.5772/intechopen.95974*


#### **Table 2.**

*Internal Combustion Engine Technology and Applications of Biodiesel Fuel*

K. Viscosity @ 40 °C mm2

Thereafter the products were put into a separating funnel and the excess alcohol,

**Unit PD WPPO**

/s 3.04 2.538

To remove methanol and water from the esterified oil a rotary evaporator was

Density @ 20 °C Kg/M3 845 825

Cetane number — 55 — Flash point °C 50 43 Fire point °C 56 45 Carbon residue % 22 0.015 Sulfur % <0.028 0.248 Gross calories MJ/kg 46.50 43.32

To complete the process reaction an alkaline catalyzed process was employed by reacting the esterified oil with methanol at 6:1 molar ratio and 1% potassium

The fatty acid for a double bond is unsaturated, so a single bond fatty acid, which is saturated, was tested using the FT-IR and confirmed by the GC–MS method. **Table 2** shows the GC–MS operating conditions while **Table 3** shows the FT-IR indicated compounds of pyrolysis biodiesel oil and their class of

The biodiesel obtained was composed of more than 20 compounds of mixed proportion whose composition and GC–MS percentage areas spectrum are presented in **Table 4**. **Table 5** has a list of test equipment utilized in the experiment. Considering percentage areas of the spectrum, the highest pick areas of the total chromatography were the following: heptadecane, n-octadecane, n-hexadecane, nonadecane, pentadecane, eicosane, tetradecane and tridecane. Eq. 1 shows the effect of linear velocity of the carrier gas in retention time which was used to

( )

µ

The components present in mixed WPPO range from carbon number C10 to C40. A large percentage of these components are made of aliphatic compounds as shown
