Recently, the increase in fuel oil demand was not supported by petroleum production due to the low productivity of old wells. Furthermore, an appropriate technology, such as Enhanced Oil Recovery (EOR) technology, is needed to maximize the productivity of the old well. Therefore, the purpose of this study was to synthesize a polymeric surfactant for the EOR process from sodium lignosulfonate (SLS) and polyethylene glycol (PEG) in various SLS to PEG ratios, namely 1:1 (PS1), 1:0.8 (PS2), and 1:0.5 (PS3). The surfactants were characterized using several methods, such as Fourier Transform-Infrared spectroscopy (FT-IR), compatibility, stability, viscosity, and phase behavior tests. The performance of the surfactants for the EOR process in different brine solution concentrations (16,000 ppm and 20,000 ppm) was also studied. The result showed that the introduction of the PEG molecule to the surfactant had been successfully conducted as FT-IR analysis confirmed. The surfactant's hydrophilicity increased with the introduction of PEG due to the increase of the ether group. A Winsor Type I or lower phase microemulsion was formed due to the high hydrophilicity. The highest oil yield (79 %) was obtained by PS1 surfactant, which has the highest PEG dosage, in a brine solution of 1,600 ppm. Therefore, it was concluded that the introduction of PEG could increase the hydrophilicity, viscosity, and EOR performance.

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Lime is one of the most commonly consumed medicinal plants in Indonesia, which must be dried to preserve its quality, but mostly by using traditional, ineffective drying method. Therefore, this study aims to investigate lime drying process a hybrid solar drying method. The hybrid solar dryer consisted of a solar dryer and Liquefied Petroleum Gas as the supplementary heater. The drying process was conducted until there was no significant weight decrease, with the drying temperature of 40, 50, 60, 70, and 80 C. Thin-layer modeling and quality analysis were also conducted. The experimental results indicated that 5 h was required to sufficiently dry the lime at 80 C, while drying at 40 C took 24 h to finish. The drying rate curve of lime suggested that lime drying mostly happened during the falling-rate period. Moreover, the average efficiency of the hybrid solar dryer ranged from 5.36% to 38.61%, which increased with temperature. From the 10 thin-layer drying models used, the Wang and Singh model was the most suitable to describe the drying behavior of lime. The effective diffusivity values of the limes and the activation energy value during hybrid solar drying were within their respective acceptable range for agricultural products. However, as the drying temperature was increased from 40 to 80 C, the total phenolic content and vitamin C content decreased, from 87.3 to 27.8 mg GAE/100 g dry limes and 0.118 to 0.015 ppm, respectively. It can be concluded that hybrid solar dryer is able to sufficiently dry the lime, with acceptable drying time and dryer efficiency, although using high drying temperature will decrease the quality of dried lime. Further modifications and improvements to the hybrid solar dryer are required to maximize the quality of dried lime while still maintaining fast and effective drying process.

In this study, hybrid solar drying of coffee beans was performed, and energy analysis was carried out, to assess the system’s performance, in terms of energy efficiency, compared to solar drying and the open sun drying method. The dryer has three compartments: solar collector for collecting solar radiation, drying chamber, and a Liquid Petroleum Gas burner, which acted as an auxiliary heater to assist the thermal energy. The drying chamber has four trays for placing the dried product. The initial moisture content of coffee beans was 54.23% w.b and was reduced to the final moisture content between 11-12% w.b. The coffee beans dried faster when subjected to the solar hybrid drying method, compared to other methods, with the dryer temperature of 40°C, 50°C, and 60°C. Results indicated that the coffee beans’ drying times varied from 10 to 14 hours. However, at temperature 50°C and 60°C for the 1st tray, the water content was reduced more rapidly compared to the other tray. From the results of this study, we can see the different efficiency of solar collector that shows of 54.15% at variable temperature 60°C for drying time 12:00 to 14:00 p.m for hybrid solar drying and for the solar drying process is 50.07% at the range of drying time 12:00 to 14:00 p.m. Mathematical modelling shows that Page model is the most suitable for describing the coffee beans’ drying behaviour using a hybrid solar dryer. The effective diffusivity values found in this experiment are all in the acceptable range for most agricultural products. ©2020. CBIORE-IJRED. All rights reserved

In this study, we aimed to energetically and exergetically evaluate the usage of a hybrid solar dryer system for cassava drying via a series of drying experiments. The experiments were performed beginning at 10.00 A.M. (hereafter, in local time) until the moisture content of cassava starch became constant at a value less than 14% on a wet basis at drying temperatures of 40°C to 60°C and drying times of 180-240 min. The results demonstrated that the highest overall dryer energetic efficiency was 20.82%, which was achieved at a drying temperature at 60°C, and that the maximum energetic efficiency of 27% was recorded at 11.00 A.M. The exergy flows fluctuated during the drying process and were dependent on the solar radiation and drying conditions; however, the exergetic efficiency of the dryer was 25.1%-73.8%. Comparison of the fitting models denoted that the Page model was the most suitable model for describing the experimental drying performances. The calculated effective diffusivity constant (D eff ) and the activation energy (E a ) during the drying process from 50°C to 60°C were 3•× 10 −10 m 2 /s and 15.3 kJ/mole, respectively.

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One promise source of alternative energy is biodiesel from rubber seed oil, because the raw materials available in plentiful quantities and can be renewed. In addition, the rubber seed is still lack of utilization, and Indonesia is one of the largest rubbers producing country in the world. The objective of this research is to studied on biodiesel production by esterification process. Parameters used in this study are the ratio of catalyst and temperature and its influence on the characteristics of the resulting biodiesel product. Characterization of rubber seed include acid content number analysis, saponification numbers, density, viscosity, iodine number, type of free fatty acids and triglyceride oils. The results of analysis showed that rubber seed oil content obtained is 50.5%. The results of the GCMS analysis showed that a free fatty acid level in rubber seed is very high. Conversion into bio-diesel oil is obtained by at most 59.91% and lowest 48.24%.