• Energy Research

This research investigated the effects of magnetic metal oxide catalysts and operating parameters on the transesterification of waste cooking oil to biodiesel in a continuous reaction setup. Ferric oxide (Fe2O3) was incorporated in alkaline oxide to provide magnetic characteristics, instead of using filters to capture catalysts within the heating zone. Biodiesel production was conducted in a packed glass tubular reactor under ultrasonication in a water bath. The reaction parameters included reaction temperature, amount of catalyst, residence time, and ultrasonic power. Three different catalysts were studied, including calcium oxide on Fe2O3, zinc oxide on Fe2O3, and magnesium oxide on Fe2O3. The results revealed that the biodiesel yield increased with increasing reaction temperature, amount of catalyst, residence time, and ultrasonic power. The optimized biodiesel yield of 94.3% was produced over calcium on Fe2O3 at 65 °C, the methanol-to-oil ratio of 11:1, the residence time of 6.2 min, and the ultrasonic power of 185 W. An increase of reaction temperature to 75 °C resulted in a decline in biodiesel yield to 91.3% due to methanol evaporation at higher temperatures. The catalytic stability was also tested at 60 °C, 6 wt% catalyst, and 185 W ultrasonic power. It was revealed that calcium oxide on Fe2O3 catalyst demonstrated superior catalytic stability with a biodiesel yield decrease of only 10% after 34 days on stream. This suggested the magnetic feature of the catalyst helped prevent leakage of the catalyst from the system. Moreover, the quality of biodiesel met the ASTM D6751 standard for transportation fuel.

An increase in the energy system used promote new renewable source produced to improve human well-being quality. The objective of this work is to study the supercritical ethanol liquefaction reaction using rice husk as a feedstock and graphene oxide as catalyst. Characterization of the catalyst was conducted using thermal gravimetry analysis technique and N2Sorption. Results revealed that graphene oxide treated with 1.5 M sulfuric acid solution gave the largest surface area of 110.5 m2/g. This research promised to optimize bio-fuel production using Box–Behnken method with 15 experimental data. The significant of the 3 parameters (catalyst amount, temperature and reaction time) was demonstrated using the ANOVA method. These statistical data were employed to illustrate contour data and response surface. A polynomial equation was also derived from the experimental data and used to valid with calculated data from the equation. Optimization was discussed in term of yield and operating cost. Optimum conditions were of 51.8% bio-fuel yield were derived from supercritical ethanol liquefaction at reaction time of 298 °C, 60 min reaction time, and 3.4 grams of SO4(1.5)/GO catalyst. Bio-fuel derived the optimum condition gave a high heating value as high as 30.15 MJ/kg, which is in the range of transportation fuel.

A rise in utility consumption in rural areas have promoted the demand for the development of solar-based technologies for water purification system. This research aimed to develop a slanted double-slope solar distillation unit (SDSD) assisted by heat absorbers, which is employed as a distillation unit for generating clear distilled water from underground water. The prototype SDSD distillation unit developed in this research was evaluated based on production efficiency, productivity, distillation rate and temperature measured at different locations inside the device. Significant parameters that were varied included the types of heat absorber used (gasket, rubber, aluminum, high carbon steel and zinc) and the size of heat absorber (10 to 90% of surface area inside the SDSD). Results demonstrated an increase in the production of distilled water as the surface area of heat absorber decreases. This is because a reduction in surface area of the heat absorber allowed a more intense sunlight to enter the system. Maximum productivity peaked at 1.2 liter per day (24.9% efficiency). Monitored data in both the upper and bottom part of the distillation unit revealed the highest distillation rate at 15:00 each day. Distillation rate decreases with water height and insulator’s thermal conductivity, but increase with water speed. Additionally, a mathematical model was proposed which was capable of accurately predicting the production efficiency and productivity as a function of the heat absorber’s size and distillation time. Under the same operating conditions, aluminum was found to generate the best results relative to other types of heat absorber.

The aim of this research is to investigate mass and heat transfer of anodic aluminum oxide in packed-bed thermocline vessel with molten salt system (5% Lithium, 20% sodium, 50% potassium and 25% calcium). According to the computational fluid dynamic simulation, the ceramic ball that is packed inside the vessel does not have a significant impact on the mass transfer of anodic aluminum oxide in the molten salt system. Heat storage performance testing was conducted in a thermocline vessel (packed-bed zone 0.7 m in length and 0.3 m diameter) and molten salt flow rate between the ranges of 0.5–0.7 m3/h. Two different molten salt systems were studied including a normal molten salt system and a molten salt system with 0.5 wt% anodic aluminum oxide. An increase in molten salt flow rate have a positive impact on heat transfer inside the vessel due to the increase in turbulence of the flow. A decrease in charging time from 3.75 h to 3.5 h was observed for molten salt with 0.5 wt% anodic aluminum oxide. A seven-cycle charge/discharge test revealed that addition of 0.5 wt% anodic aluminum oxide resulted in a smaller reduction in heat transfer efficiency and actual energy storage. Heat storage decreased from 20.42 to 19.54 MJ corresponding heat transfer efficiency of only 87 to 85% for molten salt system consisting of anodic aluminum oxide.

Shortage in supply for petroleum-based liquid fuel have promote researches in the area of alternative energy such as blended fuel containing various amount of bio-ethanol derived from waste lignocellulosic biomass. This paper aims to optimize the enzymatic saccharification by varying reaction temperature, enzyme loading and time required to hydrolyzed palm empty fruit bunch (P-EFB). The best saccharification conditions were used to generate reduced sugar, consisting of glucose, fructose which was then passed through the fermentation process to produce bio-ethanol. Optimal saccharification of P-EFB was found to be conducted at temperature of 45°C, enzyme loading of 20 FPU/g and reaction time of 12 hours. The optimum concentration of reduced sugar produced in the pre-hydrolyzed slurry was 11.4 g/L. Fermentation of pre-hydrolyzed slurry in 5 g/L yeast solution was conducted at 40°C and fermenting time of 24 hours. Product from fermentation contained 29.5 g/L bioethanol or bio-ethanol yield of 68.7 %.

The objective of this research is to investigate the parameters for supercritical ethanol liquefaction of rice straw over sulfated graphene oxide. Graphene oxide was synthesized from thermal treatment of humic acid and then treated with different concentration of sulfuric acid using the wet impregnation technique. Results from liquefaction demonstrated that reaction temperature helped support the production of biofuel, but increase the formation of gas due to cracking reaction. An increase in sulfuric acid helped increase the amount of biofuel produced at first. However, as the sulfuric acid concentration increased higher than 6M, biofuel started to decrease because it is turned into gas and char products. Cracking and isomerization reactions are responsible for these products. The amount of catalyst also have an impact on the liquefaction reaction when it was increased from 5% to 10%. However, as the amount of catalyst increased further the liquefaction did not have a significant change in the ability to produce biofuel. The liquefaction reaction was optimized at 320 ºC, 6M sulfuric acid concentration and 10wt% catalyst producing 33.4% biofuel.

This research aimed processing of Leucaena Leucocepphala in a fluidized-bed reactor with catalysts for renewable energy. The reaction was tested over different type of catalysts such as natural zeolite, kaolin and dolomite. These catalysts were loaded under the heating zone with a supplementary hot filter. The rate of feedstock added in the reactor was 1 kg/h and the pyrolysis temperature was 500 °C. Product yields was calculated after each experiment was completed.The results demonstrated an optimum bio-oil yield of 65.1 wt% after undergoing fast pyrolysis. A reduction in bio-oil yield was observed when natural zeolite, kaolin and dolomite was employed during fast pyrolysis. The minimum bio-oil yield recorded for the dolomite catalyst was 54.5 wt%. On the other hand, kaolin catalyst produces a maximum bio-oil yield of 59.6 wt%. The organic content of bio-oil from kaolin catalyst increased significantly compared with other catalysts. Addition of an ESP condenser, instead of water-cooled condenser resulted in bio-oil with the highest heating value (HHV). Higher heating value of bio-oil derived from natural zeolite catalyst maximized at 35.8 MJ/kg and 37.3 MJ/kg, respectively. The range of hydrocarbon component of bio-oil was C15–C44 for ESP condenser and C12–C35 for water-cooled condenser. The availability of bio-oil was optimized when natural zeolite catalyst added into the process. On the other hand, density and viscosity of bio-oil was increased when dolomite catalyst was used. Additionally, the presence of dolomite catalyst reduced acidic compounds such as 2-Octenoic acid (C8H14O2) and Methyl propiolate (C4H4O2) in the bio-oil. Bio-oil yield was found to be significantly improved by the large pore diameter and small surface area of the catalyst. Among the three catalysts in was observed that kaolin catalyst gave the highest bio-oil yield. Natural zeolite catalyst was found to improved bio-oil product’s thermal quality. However, bio-oil with better viscosity and lower acidity was produced from the dolomite catalyst.