Experimental Investigation of Sand Box Biodiesel Performance in an Internal Combustion Engine

Experimental Investigation of Sand Box Biodiesel Performance in an Internal Combustion Engine

Tunde F. Adepojua,*, Abiodun A. Okunolab, Dahunsi O. Samuelc

aChemical Engineering Department, Landmark University, Omu-aran, P.M.B. 1001, Kwara State, Nigeria.

bAgricultural & Biosystem Engineering Department, Landmark University, Omu-aran, P.M.B.

1001, Kwara State, Nigeria

cDepartment Biological Science, Landmark University, Omu-aran, P.M.B. 1001, Kwara State, Nigeria

*Address of Corresponding Author: aChemical Engineering Department, Landmark University, Omu-aran, P.M.B. 1001, Kwara State, Nigeria.

A four stroke single cylinder air cooled direct internal combustion engine was used to investigate engine performance; CO, NOx, smoke opacity, flue gas temperature and brake specific fuel consumption with the Sand box Biodiesel blends Biodiesel. Biodiesel was produced from Sand boxoil by two steps (acidic and basic).The experiment was carried out in triplicate to determine the production conditions with optimum yield. The produced Biodiesel had fuel properties which satisfied both ASTME D6751 and EN 1424 standards. The fatty acid profile of the Biodiesel revealed the dominant fatty acids were linoleic (64.50%), oleic (17.54%) andpalmitic (12.70%). Exhaust emissions from an internal combustion (I.C.) engine revealed that the CO and NOx emissions reduction were 60% and 58% at B20 respectively. Meanwhile, the HC emission reduction was found to be 60% at B20, Smoke opacity emission reduction was found to 64% at B20, BSFC was found to be 42% emission reduction at B20. However, the flue gas temperature and BTE increased by 12% and 45%, respectively. Hence, Sand box Biodiesel is an environmentally friendly engine fuel.

Keywords:Sand box, Biodiesel, Fatty acids, Intenal combustion engine, Exhaust emissions.

1. Introduction

   Few people realize that vegetable oilseeds can be used for more than frying fast food. Indeed, Rudolph Diesel's first public exhibition of the internal combustion technology that was to later bear his name featured an engine running on peanut oil. He envisioned freeing small businesses from the monopolistic coal and steam power of the day by using organic fuels in his engine. Unfortunately, it turned out that his engine also lent itself to burning low-grade fractions of petroleum, and the rest is history.Diesel engine manufacturers optimized the design for lighter oils, and the use of vegetable oil never really got a chance.But, experimenters throughout the world have been reviving Diesel's vision, and vegetable oilseeds is finding increasing use, particularly in the US, UK, Germany, and Australia.

   Because of this heritage, the fuel injection pump and the fuel injectors in modern diesel engines won't work on room temperature vegetable oilseeds because of its thickness [1]. However, there are three common ways to thin vegetable oilseeds so it can be used in diesel engines, this includes; blend the vegetable oil with a lighter fuel, heat the vegetable oil until it becomes thin enough, and changing the chemical composition of the vegetable oil [2].

   Blending is fraught with problems, and although some enthusiasts swear by it, others end up swearing at it, as they damage expensive injection pumps with the heavier fluid. Some have suffered explosions when trying to mix extremely lighter fuels, like gasoline, with vegetable oil. Those reporting success seem to be limited to a mix no more than 50/50 with petro-diesel at no colder than "shirt sleeve" temperatures, on a few engines that have very robust injection pumps. The process of heating vegetable oil to about 80°C (or about 180°F) decreases its viscosity, easing its way through pumps and injectors, which cools and gels. This causes damage to the engine and can alsoresult in a lot of heat wastage [3]. The presence of impurities in the oil and

   water in the fuel can also cause expensive engine damage.But, the method of changing the chemical composition, also known as transesterification process (Biodiesel), is safe, reliable, cost effective, reduces pollution, and will work in almost any diesel engine without modification [3,4].

   Internal combustion (I.C.) engines play amajor role in transportation, industrial power generation and in the agricultural sector. There is a need to search and nd ways of using alternative fuels, which are preferablyrenewable and also emit low levels of gaseous and particulate pollutants in internalcombustion engines. As per the literature survey, fuels like vegetable oils, Biodiesel (transistorized vegetable oils to methyl esters), alcohols,natural gas, biogas, hydrogen, liqueed petroleum gas (LPG), etc. are being investigatedby researchers for engine applications. In the case of agricultural applications, fuels that can be produced inrural areas in a decentralized manner, near the consumption points will be favoured [4, 5]. Thepermissible emission levels can also be different in rural areas as compared to urban areason account of the large differences in the number density of engines [6]. Many researchers have worked on the conversion of edible and non-edible vegetable oilseeds such as beniseed (Sesamum indicum), sorrel oil (Hibiscus sabdariffa), coconut oil, linseed, Jatropha, Karanja (Pongamia glabra), kusum(Schlerlchera trijuga), pongamia, etc, to Biodiesel, separately to study the performance andemission characteristics of I.C. engine [1,2,3,4]. However, competitions for commercial edible vegetable oilseeds which are obtainable from just about a dozen species of plant have necessitated the search for oils from underutilized tropical plants such as (Sand box). Despite the potential of this under-utilized species as a source of less consumed food and medicine, to authors best knowledge, sparse information is available on the suitability of its Biodiesel in I.C. engine whose emission characteristics hitherto remains

   untapped. Therefore, the study is aimed at investigating Sand box biodiesel as a suitable fuel in an Internal Combustion Engine.

2. Materials and Methods

   1. Materials

      TheSand box oil used for this study was collected from the Department of Agricultural Engineering, University of Markudi, Nigeria. The convectional fuel (AGO) was purchased from petrol station in Omu-aran. All chemicals used were all of analytical grade.

   2. Experimental procedure

      1. Acid catalyzed

         The crude unrefined Sand box oil was golden yellow in colour. The FFA was determined through the standard titrimetric method. The initial acid value of the oil was obtained to be 4.22

         ± 0.01 mg KOH/g oil (FFA level of 2.11 ± 0.01 %), which is far above the < 1.50 specification limit for satisfactorily alkaline catalyst transesterification reaction. Hence, the FFAs were first esterified with catalyst (H2SO4). Using the standard AOAC method, the acid value of separated product at the bottom was determined. This process was repeated in triplicate and the product having acid value < 2.11 ± 0.01 mg KOH/g (FFA = 1.06) oil was used for the alkalis transesterification stage (step 2). Table 1 shows the reaction time, concentration of acid (H2SO4) and methanol/oil molar ratio used with the acid value and FFAs computed.

         Table 1: Pretreatment process – Acid catalyzed esterification

         Variables		Values
         H2SO4 conc. (% v/v)	1.30	1.45	1.60
         Methanol/oil molar ratio	4	5	6
         Reaction time (min)	30	40	50
         Titrimetric acid values (mg KOH/ g oil)	3.20	2.11	2.54
         % FFA	1.60	1.06	1.27

      2. Basic (Alkalis) catalyzed

         According to the method of [7], the reaction was carried out with 5:1 methanol/oil molar ratio using 0.55% KOH as an alkaline base catalyst. The amount of KOH (5.5 g/l of preheated Sand boxoil) was reached based on the amount needed to neutralize the unreacted acids (2.11 mg KOH/g oil) in this stage. The reaction was carried out at 60 oC for 30 min in a reactor. At the completion of the reaction,the product was transferred to a separating funnel for glycerol and biodiesel separation. Glycerol was tapped off and the left was washed with ionized water to

         remove residual catalyst, glycerol, methanol and soap. The washed biodiesel was further dried over heated CaCl2 powder. The biodiesel yield was determined gravimetrically as described in Eq.1. The experiment was carried out in triplicate in order to select the optimum condition with highest yield (Table 2).

         %( ) =

         (1)

   3. Physicochemical analysis of the Sand box oil and Biodiesel

      The evaluation of physicochemical and other properties of the oil and biodiesel was determined by [8], method, Wijs method and the methods reported by [9]. The quality of Biodiesel is very important for the performance and emission characteristics of a diesel engine. Thus, thebiodiesel produced wassent to the Nigeria National Petroleum Company (NNPC) Laboratory for chromatography analysis of fatty acids present in the biodiesel quality testing using standard methods.

   4. Emission Characterization of BiodieselI.C. engine

      The blend of biodiesel and AGO were mixed in different proportions such as B10, B20, B30, B40 and B50. The same procedure was repeated for 100% AGO (B0) and 100% biodiesel (B100).The emissions (CO,NOx, HC, Smoke opacity and Flue gas temperature) were recorded using EGA4 palm top flue gas analyzer having Ni-MH rechargeable battery, opacity of smoke was measure using smoke meter. Brake specific fuel consumption (BSFC) and brake thermal efficiency were computed.

3. Results and Discussion

   1. Oil production characteristics

      1. Pretreatment process -Acid catalyzed esterification

         This section describes a series of tests that were conducted to develop the acidcatalyzed pretreatment process. Since Sand box oiltends to have variable properties that could influence the repeatability of the tests, the pretreatment step was repeated in triplicate and the mean value of yield (acid values) was titrimetrically obtained. % FFA was computed (Table 1). The results showed that the FFA of 1.06 mg KOH/g oil at working variable of reaction time, 40 min, methanol/oil molar ratio, 5:1 and 1.45 (% v/v) H2SO4 conc. were suitable for the best yield in the second step alkalis transesterification process.

      2. Alkalis catalyzed transesterification process

         The yield of biodiesel obtained during the alkalis catalyzed transesterification process was 92.70% (w/w) at the following variable conditions, 0.55% KOH, 5:1 Methanol/oil molar

         ratio, 60 oC reaction temperature and 30 min reaction time. The validity of the biodiesel was confirmed by carrying out three independent replicates experiments(Table 2).

         Table 2: Alkalis catalyzed transesterification process

         KOH (%)	Methanol/oil molar ratio	Reaction temp. (oC)	Reaction time (min)	Sand Box Biodiesel yield % (w/w)
         0.55	5:1	60	30	92.40
         0.55	5: 1	60	30	92.50
         0.55	5:1	60	30	92.70

         1. Physicochemical analysis and other properties of Sand box oil and Biodiesel

            1. Physical properties of the Sand box oil and Biodiesel

               In order to evaluate the quality of the crude Sand box oil and biodiesel, the content and compositions of theoil and biodieselwas subjected to physicochemical analysis and the results obtained are shown in Table 3. At room temperature, the oilwas golden yellow in colour and the biodiesel was light yellow. The refractive index increased but the moisture content decreased after conversion of oil to biodiesel,indicating a good shelf life characteristic of oil. Observations on the colour, moisture content and refractive index of the oil and biodiesel agreed with previously published report [10]. The specific gravity of the oil was determined as 0.93 which was reduced to 0.86 after conversion, indicates that the oil and biodiesel are less dense than water with refractive index of 1.480 and 1.490, respectively. Although,[11], reported mean value of 0.98 on specific gravity for the same oil,[12] reported a range between 0.874-8.2312 for most

               of the vegetable seed oils. The viscosity, which is a measure of the resistance of material to shear, was determined to be 6.32 mm2/s and 2.78 mm2/s, respectively. The higher value obtained for the oil in this study indicates the oil could be used as lubricant inengine parts in the tropics if

               left overnight as solidification temperature of the oil is below 10oC at any season [13]. The value of densities (1.42 g/cm3 and 0.92 g/cm3) obtained in this present work were in line with what was obtained by [10].

            2. Chemical properties of the Sand box oil and Biodiesel

         Table 3 contains results obtained for the chemical properties of crude Sand box oil and biodiesel. The high acid value of the seed oil showed that it is non-edible oil which improves it suitability for biodiesel production. This can be used to check the level of oxidative deterioration of the oil and Biodiesel by enzymatic or chemical oxidation. The acid value is expected to range from 0.00 – 3.00 mg KOH/g material, before it can find application in industries but the value is high for oil under study. That was why acid value was made fit by subjecting the oil to biodieseland this may also improve its quality for industrial purposes [11]. A high Saponification value was obtained for the oilseed, suggesting high concentration of triglycerides suitable for Biodiesel production. The iodine value of the seed oil was high (125.90 g of I2/100 g of oil), which signified the oil contained a substantial level of unsaturation and could be used to quantify the amount of double bondspresent in the oil which reflects the susceptibility of oil to oxidation before conversion to biodiesel. Peroxide value measures the content of hydro-peroxides in the oil and its low value indicates high resistance to oxidation. The value obtained for the seed oil and biodiesel in this work were well within the limit stipulated for vegetable oils and Biodiesel. This shows that the oil is not rancid and considered stable [14]. The HHV determined for the oil was

         39.28 MJ/kg and it is within the range earlier reported [15] for vegetable oils (37.47 40.62 MJ/kg). The rise in the HHV after conversion of oil to biodiesel proved that the oil is not only good for Biodiesel production, but can be suitably used as fuel in I.C. engine.

         Table 3: Properties of Sandbox oil and BiodieselComparison to Biodiesel Specification

         Parameters	Sand box	Biodiesel	ASTM	EN 14214
         	oil		D6751
         Physical properties
         Colour	Golden yellow	Light yellow
         Moisture content %	0.40 ± 0.001	0.001 ± 0.001	0.05 max	0.02
         Specific gravity	0.930 ± 0.01	0.860 ± 0.015	0.86-0.90	0.85
         Viscosity (mm2/s) at 40oC	6.32 ± 0.01	2.78 ± 0.02	1.9-6.0	3.5-5.0
         Density (g/cm3) at 25oC	1.42 ± 0.01	0.92 ± 0.02	0.84	0.86-0.90
         Chemical properties
         Iodine value(g I2/100g )	125.90 ± 0.10	116.40 ± 1.40	–	120 max
         Acid value(mg KOH/g oil)	4.22 ± 0.10	2.34 ± 0.15	< 0.80	0.5 max
         %FFA (as oleic acid)	2.11 ± 0.01	1.17 ± 0.02	–	–
         Saponification value (Mg	201.60 ± 0.50	180.20 ± 0.10	–	–
         KOH/g oil)
         Peroxide value	3.04 ± 0.10	2.48 ± 0.10	–	–
         Other properties
         Cloud point oC	–	8.00	6	12 max
         Flash point oC	–	112.00	100 min	>120
         Pour point oC	–	-14.00	– 15	–
         Diesel index	48.68 ± 0.20	56.11 ± 0.11	50.40	–
         API	20.65 ± 0.14	33. 03 ± 0.40	36.95	–
         Mean molecular mass	277.78 ± 1.60	310.77 ± 1.45
         Cetane number	45.05 ± 4.80	50.40 ± 1.20	47 min	51 min
         HHV (MJ/kg)	39.28 ± 0.30	40.30 ± 010	–	–
         Aniline point	235.74 ± 0.13	169.88 ± 0.50	331.00	–

         values are means of triplicate determination ± standard deviation of mean

         3.2.3 Other properties of the Sand box oil and Biodiesel

         Additional fuel properties such as cetane number, API, diesel index, mean molecular mass and aniline point of the oilseed and biodieselwere determined (Table 3). Cetane number is a measure of the fuels ignitiondelay and combustion quality. Standard specification for cetane number Biodiesel is 40 minimum [16]. The cetane number of the oilseed (45.05) showed that it has high fuel potential before being converted to biodiesel (cetane number- 50.40). The cetane number reported for most vegetable oils range from 27.6 to 52.9 [15, 17]. The API, diesel index and aniline point of the oil and biodieselwere comparable with other reported work[9]. The two steps transesterification of the oil improved its fuel properties.

         1. Fatty acid profile of the Sand box oil and Biodiesel

            Gas chromatography analysis of fatty acids present in the oil and biodiesel shown in Table 4. The results indicated that the oil is highly unsaturated. The dominant fatty acids were linoleic (58.52%), oleic (20.31%), palmitic (16.01%), stearic (3.10%), linolenic acid (C18:3) (1.60%) and others (0.46%). Whereas, the dominant fatty acids found in biodieselwere linoleic (64.50%), oleic (17.54%), palmitic (12.70%), stearic (1.74%), linolenic acid (3.50%) and others (0.02%) The values observed in this work are within the ranges previously reported [18,19].This indicates that fatty acid composition will play a dominant role in establishing the cetane number [19, 20].

            Table 4: Fatty Acids Compositions of the Sand box oil and Biodiesel Produced

            Parameters Compositions %

            Oil Biodiesel

            Palmitic acid (C16:0)	16.01	12.70
            Stearic acids (C18:0)	3.10	1.74
            Oleic acids (C18:1)	20.31	17.54
            Linoleic acids (C18:2)	58.52	64.50
            Linolenic acid (C18:3)	1.60	3.50
            Other	0.46	0.02
            Total	100	100

         2. Emission characterization

         The test was conducted on a four stroke, air cooled, single cylinder direct injection diesel engine, developing a power output of 3.23 kW at a constant of 2600 rpm. Table 5 shows the specifications of the engine. The characterization of fuel behavior with respect to emissions and performance was carried out by determined the CO,NOx, HC, Smoke opacity, Flue gas temperature, BSFC and BTE.

         Table 5: Engine specifications

         Parameter Specification

         Type of engine Single cylinder

         Engine brand name 165F, Direct injection, four- stroke, Internal Combustion Engine.

         Stroke length 0.11 m

         Bore and stroke 87.5 mm x 110 mm

         Cooling method Air

         Injector operating pressure 200 bar/ 23 oC BTDC

         Dynamometer current Eddy current

         Compression ratio 16.5:1

         Response time 4 micro seconds

         Rated speed 2600 rpm

         Resolution in 1 degree 360 degree encoder with a resolution of 1

         Rated power 3.2 Kw

         1. Carbon monoxide (CO) emission (ppm)

            CO is only a very weak direct greenhouse gas, but has important indirect effects on global warming. CO is an ozone precursor, but to a lesser extent than unburned hydrocarbons or nitrogen oxides.Biomass burning and fossil fuel use are the main sources of man-made CO emission. The most potential control is through direct reduction in fossil fuel use. Since the emission of CO depended on rotational speed, it decreased with increased in concentration of Biodiesel.

            Figure 1 shows the variation of CO with blends at different speed of revolution of I.C. engine. At the speed range of 800-1000 rpm, the CO emission was found to be highest at B0, followed by B10, B50 and B100. The CO decreases with increases in concentration of Biodiesel

            0.25

            0.2

            CO (%) Emission

            CO (%) Emission

            CO (%) at 800-

            0.15 1000 rpm

            0.1 CO (%) at 1000-

            1200 rpm

            0.05

            0

            B0 B10 B20 B50 B100

            Blends

            CO (%) at 1200-

            1400 rpm

            Fig. 1: CO emission vs. blends

            blends as fuel [21].At speed range of 1000-1200 rpm, the emission of B0 and B10 was found to be the highest compared with blends of B20 and B100. B50 has the lowest emission at this speed

            range. It was also observed that at highest speed range (1200-1400 rpm), the CO emission concentration was lowest at B50 while B0 has the highest emission concentration.Therefore, the CO emission concentration at B20 is the lowest with 60% emission reduction when compare with B0 (100% AGO).

         2. NOx emission

            NOx should not be confused with N2O, which is a greenhouse gas. It is the total concentration of NO and NO2. When NOx and volatile organic compounds (VOCs) react in the presence of sunlight, they form photochemical smog, a significant form of air pollution, especially in the summer. It adverse effect is damage to the lung tissue and reduction in lung function [22]. Its can also forms nitric acid which contributes to acid rain if the combusion emission is not regulated in the environment. NOx also increase in proportion to ignition advance, regardless of variations in the air/fuel ratio.

            Figure 2 shows the variation of NOx emission concentration with the blends at different speed ranges. B20 at the highest speed range (1200-1400 rpm) has the lowest NOx concentration, followed by B10, B50, B0 and B100. At 1000-1200 rpm, B10 and B20 were found to have the same NOx concentration been the lowest, followed by B0, B50 and B100. Similarly, the highest NOx concentration was observed at B100 within the range of 800-1000 rpm, followed by B0, B50, B10 and B20. Hence, B20 at highest speed range has the lowest NOx emission concentration with 58% reduction compared to B0.

            2000

            1800

            1600

            1400

            NOx (ppm) at 800-

            1000 rpm

            2000

            1800

            1600

            1400

            NOx (ppm) at 800-

            1000 rpm

            200

            0

            200

            0

            B0 B10 B20 B50 B100

            Blends

            B0 B10 B20 B50 B100

            Blends

            1200

            1000

            800

            1200

            1000

            800

            NOx (ppm) at 1000-

            1200 rpm

            NOx (ppm) at 1000-

            1200 rpm

            600

            400

            600

            400

            NOx (ppm) at 1200-

            1400 rpm

            NOx (ppm) at 1200-

            1400 rpm

            NOx (ppm) Emission

            NOx (ppm) Emission

            Fig. 2: NOx emission vs. blends

         3. HC (Hydrocarbon) emission

            The exhaust gases emitted by 4-cycle spark I.C. engine does not operate at 100% efficiency, and the air/flue mixture when burned produces exhaust gases containing various pollutants. Among these are the HC made up of principally of minute particles of unburned gasoline; these particle react photo-chemically with sunlight to produce smog; and NOx which combines with water to produce so-called acid rain. HCs are measured in ppm (parts per million). Their presence in the exhaust stream is a result of unburned or partly burned fuel, and engine oil. HC emissions increase in proportion to ignition advance, except at very lean air/fuel ratios. Factors such as poor mixture distribution, ignition misfires and low engine temperatures, will all cause significant increases in HC.

            Figure 3 shows the variation of HC emission with the blends at different speed ranges. The figure showed that at all speed ranges, the HC emission was found to be the highest at B0;

            100

            100

            HC (ppm) at

            1000-1200 rpm

            HC (ppm) at

            1000-1200 rpm

            HC (ppm) Emission

            HC (ppm) Emission

            this is followed by B100, B50, B10 and B20. B20 at a speed range of 1000-1200 rpm has the lowest HC emission with 60% reduction when compare with B0.

            250

            250

            200

            200

            150

            HC (ppm) at 800-

            1000 rpm

            150

            HC (ppm) at 800-

            1000 rpm

            50

            HC (ppm) at

            1200-1400 rpm

            50

            HC (ppm) at

            1200-1400 rpm

            0

            0

            B0

            B10 B20 B50 B100

            B0

            B10 B20 B50 B100

            Blends

            Blends

            Fig. 3: HC emission vs. blends

         4. Smoke opacity emission (%)

            Smoke opacity is a measurement of smoke density from 0% clean and 100% dirty. Smoke opacity can be in manyshades including grey/black (unburnt fuel),blue (burnt oil worn engine) or white(water condensation).It is the level of peak smoke opacity for diesel-powered motor vehicles. The level of opacity measurement remains the core of Federal, State and Local air pollution control effort as more visible emission observers verify now than ever before.

            Figure 4 shows the variation of smoke opacity with the blends ratio at various speed ranges. B0 at the speed range of 1200-1400 rpm has the highest smoke opacity, followed by B100, B50, B10 and B20. B20 has the lowest smoke opacity at speed range 1000-1200 rpm.

            Whereas, B0 at the lowest speed (800-1000 rpm) range has the lowest emission of smoke opacity with 64% reduction.

            30

            25

            Smoke opacity (%)

            Smoke opacity (%)

            Smoke opacity (%)

            20 at 800 – 1000 rpm

            15 Smoke opacity (%)

            at 1000-1200 rpm

            10

            Smoke opacity (%) at 1200-1400 rpm

            5

            0

            B0 B10 B20 B50 B100

            Blends

            Fig. 4: Smoke opacity vs. blends

         5. Brake specific fuel consumption (BSFC) emission

            The BSFC is the amount of fuel which an engine consumed for each unit of break powers per hour. It indicates the efficiency with which the engine develops the power from fuel. Majorly used to compare the performance of different engine but always tends to be the same for similar engine.

            Figure 5 shows the graph of variation of BSFC with the blends at various speed ranges. B50 at all speed ranges has the highest BSFC with 36% increase when compared with B0.

            0.06

            0.06

            BSFC (L/Kw.h) at

            1000-1200 rpm

            BSFC (L/Kw.h) at

            1000-1200 rpm

            BSFC (L/Kw.h)

            BSFC (L/Kw.h)

            Although, the BSFC is the same at all speed ranges for B0. B20 at the speed range of 800-1000 rpm has the lowest BSFC with 42% reduction when compared with B0.

            0.12

            0.12

            0.1

            0.1

            0.08

            BSFC (L/Kw.h) at

            800-1000 rpm

            0.08

            BSFC (L/Kw.h) at

            800-1000 rpm

            0.04

            0.04

            BSFC (L/Kw.h) at

            1200-1400 rpm

            BSFC (L/Kw.h) at

            1200-1400 rpm

            0.02

            0.02

            0

            0

            B0 B10 B20 B50 B100

            Blends

            B0 B10 B20 B50 B100

            Blends

            Fig. 5: BSFC vs. blends

         6. Flue gas temperature (deg. C)

            In the low temperature combustion region the exhaust temperature is critical even for diesel fuel due to its negative effects on turbocharger performance, so the lower exhaust temperature observed for neat Biodiesel could be an important drawback for its applicability in future diesel engines.

            Figure 6 shows the flue gas temperature variation with the blends ratio. B20 has the lowest at the speed range of 800-1000 rpm. B10 at the speed ranges of 1000-1200 rpm and 1200- 1400 rpm has the highest flue gas temperature as well as B20 at 1000-1200 rpm and B100 at 1200-1400 rpm, respectively. This is due to lower cetane number and higher ignition delay of

            95

            95

            90

            85

            80

            90

            85

            80

            Tg (deg. C) at 800-

            1000 rpm

            Tg (deg. C) at 1200- 1400 rpm

            Tg (deg. C) at 1000- 1200 rpm

            Tg (deg. C) at 800-

            1000 rpm

            Tg (deg. C) at 1200- 1400 rpm

            Tg (deg. C) at 1000- 1200 rpm

            Flue gas temperature (deg. C)

            Flue gas temperature (deg. C)

            the blend [23]. Hence, the highest flue gas temperature was found at 1000-1200 rpm for B10, B20 and B100 with 12% increase.

            100

            100

            75

            75

            B0 B10 B20 B50 B100

            Blends

            B0 B10 B20 B50 B100

            Blends

            Fig. 6: Flue gas temperature vs. blends

         7. Brake thermal efficiency (BTE)

         BTE is the ratio of output to that of input energy in the form of fuel. It gives the efficiency with which the chemical energy of fuel is converted into mechanical work. It shows that all chemical energy of fuel is not converted to heat energy. The fuel efficiency tend to peak at higher engine speeds [24].

         Figure 7 therefore shows the BTE variation with the blends at various speed ranges. The BTE decreases as the blend ratio increases at all speed ranges. However, B100 at speed range of 800-1000 rpm has the lowest BTE with 23% reduction when compared with B0 at the same speed range. B50 has the highest BTE at the speed range 1200-1400 rpm, these shows 45% increase in the BTE when compared with B0.

         30

         30

         25

         25

         5

         BTE (%) at

         1200-1400

         0 rpm

         B0 B10 B20 B50 B100

         Blends

         5

         BTE (%) at

         1200-1400

         0 rpm

         B0 B10 B20 B50 B100

         Blends

         20

         20

         BTE (%) at

         BTE (%) at

         800-1000 rpm

         15

         15

         10

         10

         BTE (%) at

         1000-1200

         rpm

         BTE (%) at

         1000-1200

         rpm

         Brake thermal efficency (%)

         Brake thermal efficency (%)

         Fig. 7: Brake thermal efficiency vs. blends

4. Conclusion

The results obtained in this study revealed that Sand boxoil is a good candidate for biodiesel production. Two steps production processes influenced the high yield of biodiesel. Three possible experimental runs were performed in each step, the best of the operating conditions were 1.45 (% v/v) for H2SO4 conc., 5:1 for Methanol/oil molar ratio, 40 min Reaction time which gave 1.06 % for FFAin the first step, in the second step, 92.70 %(w/w) of biodiesel at 0.55% KOH, 5:1 methanol/oil molar ratio, 60 oC temperature and 30 min reaction time was achieved.

The produced biodiesel had fuel properties which satisfied both ASTME D6751 and EN 1424 standards. Emission assessment revealed 60% decreased in CO, 58% decreased in NOx, 60% decreased in HC, 39% decrease in smoke opacity and 42% decreased in BSFC at B20,

respectively. Flue gas temperature increased by 12% at B20, meanwhile, there is 45% increase in BTE at B50.

Acknowledgment

The help of Laboratory staffs of Nigeria National Petroleum Company (NNPC) in conducting the GC analysis in the company laboratories is highly valued. The effort of technical staffs of Mechanical engineering departmental at workshop is highly appreciated.

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