Makame Mbarawa - Academia.edu (original) (raw)
Papers by Makame Mbarawa
Journal of The Institute of Energy, 2006
... In this study, only the effects of the NG compositions on the DF combustion with pre-mixed NG... more ... In this study, only the effects of the NG compositions on the DF combustion with pre-mixed NG are reported. ... They are diesel vapour C12H26, the NG fuel components CH4, C2H6 and C3H8 and 12 dissociated species of air ... H, O, N, H2, OH, CO, NO, O2, H2O, CO2, N2, and Ar. ...
International Journal of Green Energy, 2010
The cold flow properties of biodiesel from various feedstocks have been a challenge in adapting t... more The cold flow properties of biodiesel from various feedstocks have been a challenge in adapting the use of biodiesel in diesel engines, especially in cold regions. The use of cold flow improvers for biodiesel helps using biodiesel in a wide range of temperature conditions. In this study, cold flow properties of biodiesel produced from non-edible feedstocks such as croton megalocarpus, jatropha curcas, and moringa oleifera oils were investigated. The evaluated properties were kinematic viscosity, cloud point, and pour point. Different transesterification methods were used to produce biodiesel from these feedstocks due to their difference in the level of free fatty acids (FFA). Croton and moringa oils were found with FFA levels of 1.68% and 0.6%, respectively; thus, one-step transesterification method was chosen for their methyl esters conversion. Jatropha oil was found with FFA level of 8.14% making a two-step acid-base transesterification method to be employed for its methyl esters conversion. The effect of water in the two-step acid-base transesterification process was also investigated for jatropha biodiesel production. The presence of water after acid pretreatment process of jatropha oil was found to reduce both product and methyl esters yield, the best option was to preheat the pretreated jatropha oil to 110°C for 10 min to evaporate water that remain during gravity separation of methanol–water phase. Blending of biodiesels from these three feedstocks with kerosene improved their cold flow properties. The reduction of cloud and pour points from −4°C and −9°C to −11°C and −15°C, respectively, of croton biodiesel was observed when blended with 20% kerosene while cloud and pour points reduction from 1°C and −2°C to −7°C and −12°C, respectively, of jatropha biodiesel was observed when blended with 20% kerosene. Similarly, the reduction of cloud and pour points from 10°C and 3°C to −3°C and −7°C, respectively, of moringa biodiesel was observed when blended with 20% kerosene.
Fuel Processing Technology, 2010
ABSTRACT In this study, biodiesel was produced from Moringa oleifera oil using sulfated tin oxide... more ABSTRACT In this study, biodiesel was produced from Moringa oleifera oil using sulfated tin oxide enhanced with SiO2 (SO42−/SnO2–SiO2) as super acid solid catalyst. The experimental design was done using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (α) = 2. The reaction parameters studied were reaction temperature (60 °C to 180 °C), reaction period (1 h to 3 h) and methanol to oil ratio (1:6 to 1:24). It was observed that the yield up to 84 wt.% of Moringa oleifera methyl esters can be obtained with reaction conditions of 150 °C temperature, 150 min reaction time and 1:19.5 methanol to oil ratio, while catalyst concentration and agitation speed are kept at 3 wt.% and 350–360 rpm respectively. Therefore this study presents the possibility of converting a relatively new oil feedstock, Moringa oleifera oil to biodiesel and thus reducing the world's dependency on existing edible oil as biodiesel feedstock.
Journal of Thermal Analysis and Calorimetry, 2010
Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum... more Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum diesel fuels due to their environmental friendliness and availability. Ignition quality in compression ignition (CI) engines is influenced by thermal characteristics and fuel properties. In this study, the effects of vegetable oil transesterification and vegetable oil–1-butanol-diesel blends on fuel properties, cetane number (CN) and thermal characteristics were experimentally investigated. Methyl esters (biodiesel) and 10% vegetable oil–10% 1-butanol–80% diesel blends were prepared from croton oil (CRO), coconut oil (COO) and jatropha oil (JAO). CN was measured in a CFR F-5 engine, and a thermogravimetric analysis (TG), as well as the determination of fuel properties of vegetable oils, biodiesels and blends was carried out. It can be observed for vegetable oils that they possess low volatility characteristics, low CN and high viscosity different from those of biodiesels, blends and diesel fuel. It was observed that biodiesels and blends exhibit similarities with diesel in the fuel characteristics, CN and TG curves.
Energy & Fuels, 2010
... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alterna... more ... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alternative fuel for diesel enginesA ... Purushothaman, K. ; Nagarajan, G. Experimental investigation on a CI engine using orange oil and orange oil with DEE Fuel 2009, 88 ( 9) 1732 1740 ...
Journal of Thermal Analysis and Calorimetry, 2010
Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum... more Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum diesel fuels due to their environmental friendliness and availability. Ignition quality in compression ignition (CI) engines is influenced by thermal characteristics and fuel properties. In this study, the effects of vegetable oil transesterification and vegetable oil–1-butanol-diesel blends on fuel properties, cetane number (CN) and thermal characteristics were experimentally investigated. Methyl esters (biodiesel) and 10% vegetable oil–10% 1-butanol–80% diesel blends were prepared from croton oil (CRO), coconut oil (COO) and jatropha oil (JAO). CN was measured in a CFR F-5 engine, and a thermogravimetric analysis (TG), as well as the determination of fuel properties of vegetable oils, biodiesels and blends was carried out. It can be observed for vegetable oils that they possess low volatility characteristics, low CN and high viscosity different from those of biodiesels, blends and diesel fuel. It was observed that biodiesels and blends exhibit similarities with diesel in the fuel characteristics, CN and TG curves.
Energy & Fuels, 2010
... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alterna... more ... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alternative fuel for diesel enginesA ... Purushothaman, K. ; Nagarajan, G. Experimental investigation on a CI engine using orange oil and orange oil with DEE Fuel 2009, 88 ( 9) 1732 1740 ...
Chemical Papers, 2010
This work presents the use of sulfated tin oxide enhanced with SiO2 (SO 42−/SnO2-SiO2) as a super... more This work presents the use of sulfated tin oxide enhanced with SiO2 (SO 42−/SnO2-SiO2) as a superacid solid catalyst to produce methyl esters from Jatropha curcas oil. The study was conducted using the design of experiment (DoE), specifically a response surface methodology based on a threevariable central composite design (CCD) with α = 2. The reaction parameters in the parametric study were: reaction temperature (60°C to 180°C), reaction period (1 h to 3 h), and methanol to oil mole ratio (1: 6 to 1: 24). Production of the esters was conducted using an autoclave nitrogen pressurized reactor equipped with a thermocouple and a magnetic stirrer. The maximum methyl esters yield of 97 mass % was obtained at the reaction conditions: temperature of 180°C, reaction period of 2 h, and methanol to oil mole ratio of 1: 15. The catalyst amount and agitation speed were fixed to 3 mass % and 350–360 min−1, respectively. Properties of the methyl esters obtained fell within the recommended biodiesel standards such as ASTM D6751 (ASTM, 2003).
Bioresource Technology, 2010
This study presents the feasibility of converting a non-edible oil source native to the Africa re... more This study presents the feasibility of converting a non-edible oil source native to the Africa region -croton megalocarpus oil to methyl esters (biodiesel) using sulfated tin oxide enhanced with SiO(2) (SO(4)(2-)/SnO(2)-SiO(2)) as super acid solid catalyst. This study was conducted using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (alpha)=2. The reaction parameters studied are: reaction temperature (60-180 degrees C), reaction period (1-3h) and methanol to oil ratio (1:6-1:24). Although the oil was found to contain high free fatty acid, however, yield up to 95% was obtained without any pre-treatment step with the following reaction conditions: 180 degrees C, 2h and 15:1 methanol to oil molar ratio, while keeping constant catalyst concentration and stirring speed at 3 wt.% and 350-360 rpm, respectively.
Frontiers of Chemical Engineering in China, 2009
This study presents findings from experiments on the preparation and characterization of locally ... more This study presents findings from experiments on the preparation and characterization of locally available fly ash, quicklime and the CaO/fly ash sorbent, synthesized using the atmospheric hydration process. The CaO was obtained from calcination of limestone in a laboratory kiln at a temperature of 900°C. The sorbents were prepared under different hydration conditions: CaO/fly ash weight ratio (1°1 to 1°3), hydration temperature (55°C–75°C) and hydration period (4–8 h). Results show that the specific surface area of CaO/ fly ash sorbents (8.8–23.6 m2/g) was higher than that of the CaO (4.78 m2/g) at all preparation conditions. The SEM micrographs show that the prepared sorbent had a more porous structure than either the fly ash or the CaO. The X-ray diffraction (XRD) analysis shows the presence of complex compounds containing calcium silicate hydrate in the synthesized sorbents. This contributed to the high BET specific surface area. The Brunauer-Emmett-Teller (BET) specific surface area was found to decrease with increase in the amount of fly ash with the ratio of 1:1 (CaO/Fly ash) giving the highest value. It was also found that an increase in the hydration time resulted in an increased BET specific surface area, although there was only a slight effect on the same by an increase in temperature.
Engineering Letters, 2009
Journal of The Institute of Energy, 2006
... In this study, only the effects of the NG compositions on the DF combustion with pre-mixed NG... more ... In this study, only the effects of the NG compositions on the DF combustion with pre-mixed NG are reported. ... They are diesel vapour C12H26, the NG fuel components CH4, C2H6 and C3H8 and 12 dissociated species of air ... H, O, N, H2, OH, CO, NO, O2, H2O, CO2, N2, and Ar. ...
International Journal of Green Energy, 2010
The cold flow properties of biodiesel from various feedstocks have been a challenge in adapting t... more The cold flow properties of biodiesel from various feedstocks have been a challenge in adapting the use of biodiesel in diesel engines, especially in cold regions. The use of cold flow improvers for biodiesel helps using biodiesel in a wide range of temperature conditions. In this study, cold flow properties of biodiesel produced from non-edible feedstocks such as croton megalocarpus, jatropha curcas, and moringa oleifera oils were investigated. The evaluated properties were kinematic viscosity, cloud point, and pour point. Different transesterification methods were used to produce biodiesel from these feedstocks due to their difference in the level of free fatty acids (FFA). Croton and moringa oils were found with FFA levels of 1.68% and 0.6%, respectively; thus, one-step transesterification method was chosen for their methyl esters conversion. Jatropha oil was found with FFA level of 8.14% making a two-step acid-base transesterification method to be employed for its methyl esters conversion. The effect of water in the two-step acid-base transesterification process was also investigated for jatropha biodiesel production. The presence of water after acid pretreatment process of jatropha oil was found to reduce both product and methyl esters yield, the best option was to preheat the pretreated jatropha oil to 110°C for 10 min to evaporate water that remain during gravity separation of methanol–water phase. Blending of biodiesels from these three feedstocks with kerosene improved their cold flow properties. The reduction of cloud and pour points from −4°C and −9°C to −11°C and −15°C, respectively, of croton biodiesel was observed when blended with 20% kerosene while cloud and pour points reduction from 1°C and −2°C to −7°C and −12°C, respectively, of jatropha biodiesel was observed when blended with 20% kerosene. Similarly, the reduction of cloud and pour points from 10°C and 3°C to −3°C and −7°C, respectively, of moringa biodiesel was observed when blended with 20% kerosene.
Fuel Processing Technology, 2010
ABSTRACT In this study, biodiesel was produced from Moringa oleifera oil using sulfated tin oxide... more ABSTRACT In this study, biodiesel was produced from Moringa oleifera oil using sulfated tin oxide enhanced with SiO2 (SO42−/SnO2–SiO2) as super acid solid catalyst. The experimental design was done using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (α) = 2. The reaction parameters studied were reaction temperature (60 °C to 180 °C), reaction period (1 h to 3 h) and methanol to oil ratio (1:6 to 1:24). It was observed that the yield up to 84 wt.% of Moringa oleifera methyl esters can be obtained with reaction conditions of 150 °C temperature, 150 min reaction time and 1:19.5 methanol to oil ratio, while catalyst concentration and agitation speed are kept at 3 wt.% and 350–360 rpm respectively. Therefore this study presents the possibility of converting a relatively new oil feedstock, Moringa oleifera oil to biodiesel and thus reducing the world's dependency on existing edible oil as biodiesel feedstock.
Journal of Thermal Analysis and Calorimetry, 2010
Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum... more Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum diesel fuels due to their environmental friendliness and availability. Ignition quality in compression ignition (CI) engines is influenced by thermal characteristics and fuel properties. In this study, the effects of vegetable oil transesterification and vegetable oil–1-butanol-diesel blends on fuel properties, cetane number (CN) and thermal characteristics were experimentally investigated. Methyl esters (biodiesel) and 10% vegetable oil–10% 1-butanol–80% diesel blends were prepared from croton oil (CRO), coconut oil (COO) and jatropha oil (JAO). CN was measured in a CFR F-5 engine, and a thermogravimetric analysis (TG), as well as the determination of fuel properties of vegetable oils, biodiesels and blends was carried out. It can be observed for vegetable oils that they possess low volatility characteristics, low CN and high viscosity different from those of biodiesels, blends and diesel fuel. It was observed that biodiesels and blends exhibit similarities with diesel in the fuel characteristics, CN and TG curves.
Energy & Fuels, 2010
... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alterna... more ... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alternative fuel for diesel enginesA ... Purushothaman, K. ; Nagarajan, G. Experimental investigation on a CI engine using orange oil and orange oil with DEE Fuel 2009, 88 ( 9) 1732 1740 ...
Journal of Thermal Analysis and Calorimetry, 2010
Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum... more Vegetable oil derived fuels for diesel engines are becoming important as alternative to petroleum diesel fuels due to their environmental friendliness and availability. Ignition quality in compression ignition (CI) engines is influenced by thermal characteristics and fuel properties. In this study, the effects of vegetable oil transesterification and vegetable oil–1-butanol-diesel blends on fuel properties, cetane number (CN) and thermal characteristics were experimentally investigated. Methyl esters (biodiesel) and 10% vegetable oil–10% 1-butanol–80% diesel blends were prepared from croton oil (CRO), coconut oil (COO) and jatropha oil (JAO). CN was measured in a CFR F-5 engine, and a thermogravimetric analysis (TG), as well as the determination of fuel properties of vegetable oils, biodiesels and blends was carried out. It can be observed for vegetable oils that they possess low volatility characteristics, low CN and high viscosity different from those of biodiesels, blends and diesel fuel. It was observed that biodiesels and blends exhibit similarities with diesel in the fuel characteristics, CN and TG curves.
Energy & Fuels, 2010
... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alterna... more ... 7. Murugesan, A. ; Umarani, C. ; Subramanian, R. ; Nedunchezhian, N. Bio-diesel as an alternative fuel for diesel enginesA ... Purushothaman, K. ; Nagarajan, G. Experimental investigation on a CI engine using orange oil and orange oil with DEE Fuel 2009, 88 ( 9) 1732 1740 ...
Chemical Papers, 2010
This work presents the use of sulfated tin oxide enhanced with SiO2 (SO 42−/SnO2-SiO2) as a super... more This work presents the use of sulfated tin oxide enhanced with SiO2 (SO 42−/SnO2-SiO2) as a superacid solid catalyst to produce methyl esters from Jatropha curcas oil. The study was conducted using the design of experiment (DoE), specifically a response surface methodology based on a threevariable central composite design (CCD) with α = 2. The reaction parameters in the parametric study were: reaction temperature (60°C to 180°C), reaction period (1 h to 3 h), and methanol to oil mole ratio (1: 6 to 1: 24). Production of the esters was conducted using an autoclave nitrogen pressurized reactor equipped with a thermocouple and a magnetic stirrer. The maximum methyl esters yield of 97 mass % was obtained at the reaction conditions: temperature of 180°C, reaction period of 2 h, and methanol to oil mole ratio of 1: 15. The catalyst amount and agitation speed were fixed to 3 mass % and 350–360 min−1, respectively. Properties of the methyl esters obtained fell within the recommended biodiesel standards such as ASTM D6751 (ASTM, 2003).
Bioresource Technology, 2010
This study presents the feasibility of converting a non-edible oil source native to the Africa re... more This study presents the feasibility of converting a non-edible oil source native to the Africa region -croton megalocarpus oil to methyl esters (biodiesel) using sulfated tin oxide enhanced with SiO(2) (SO(4)(2-)/SnO(2)-SiO(2)) as super acid solid catalyst. This study was conducted using design of experiment (DoE), specifically, response surface methodology based on three-variable central composite design (CCD) with alpha (alpha)=2. The reaction parameters studied are: reaction temperature (60-180 degrees C), reaction period (1-3h) and methanol to oil ratio (1:6-1:24). Although the oil was found to contain high free fatty acid, however, yield up to 95% was obtained without any pre-treatment step with the following reaction conditions: 180 degrees C, 2h and 15:1 methanol to oil molar ratio, while keeping constant catalyst concentration and stirring speed at 3 wt.% and 350-360 rpm, respectively.
Frontiers of Chemical Engineering in China, 2009
This study presents findings from experiments on the preparation and characterization of locally ... more This study presents findings from experiments on the preparation and characterization of locally available fly ash, quicklime and the CaO/fly ash sorbent, synthesized using the atmospheric hydration process. The CaO was obtained from calcination of limestone in a laboratory kiln at a temperature of 900°C. The sorbents were prepared under different hydration conditions: CaO/fly ash weight ratio (1°1 to 1°3), hydration temperature (55°C–75°C) and hydration period (4–8 h). Results show that the specific surface area of CaO/ fly ash sorbents (8.8–23.6 m2/g) was higher than that of the CaO (4.78 m2/g) at all preparation conditions. The SEM micrographs show that the prepared sorbent had a more porous structure than either the fly ash or the CaO. The X-ray diffraction (XRD) analysis shows the presence of complex compounds containing calcium silicate hydrate in the synthesized sorbents. This contributed to the high BET specific surface area. The Brunauer-Emmett-Teller (BET) specific surface area was found to decrease with increase in the amount of fly ash with the ratio of 1:1 (CaO/Fly ash) giving the highest value. It was also found that an increase in the hydration time resulted in an increased BET specific surface area, although there was only a slight effect on the same by an increase in temperature.
Engineering Letters, 2009