Natural fibres as reinforcement of composite have been applied during the last decade. One of natural fibre has been used as reinforcement is coir fibre. As reinforcement of composite, such fibre needs treatment to improve compatibility with its matrix with suitable treatment. In this paper, surface treatment of such fibre was conducted using sodium bicarbonate (NaHCO3) solution with various densities and soaking time differences. Mechanical and morphological properties of coir fibre were investigated. Coir fibres were soaked in the 8 wt.%, 10 wt.%, and 12 wt.% sodium bicarbonate solution for 24 hours and 120 hours. After treatment, coir fibres were characterized with tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FTIR) and x-ray diffraction (XRD). The results suggested that mechanical properties of coir fibre after sodium bicarbonate solution changed for all densities and soaking time. The coir fibre treated in 12 wt.% sodium bicarbonate for soaking time 120 hours has highest tensile strength. The surface morphology of fibre was analyzed by using SEM. It showed micropores on the fibre surface which may influence the mechanical properties of coir fibre.
Water power is a type of power obtained from the force created by flowing water. Energy created from flowing water can be harnessed as a form of mechanical energy that can be utilized to generate electricity. Undershot water wheels have been extensively used to take advantage of the water flowing from rivers or waterfalls. This research was conducted by using water turbines with bowl-shaped blades made of iron and acrylic. The diameter of the turbines was 30 cm, and the diameter of the blades was 9 cm. Four, six, and eight blades were used in the three water turbines for this research. The blades were discharged and loaded to turn the turbine to generate force. The results of the study showed that the highest efficiency (η = 74.22%) was found in the six-blade turbine with a discharge of 0.01228 m 3 /s. It can be concluded that water turbines with bowl-shaped blades can be used as an alternative energy in small-scale electric generators.
This research presented the influence of treated coir fiber with sodium bicarbonate on wettability and interfacial shear strength (IFSS) of coir fiber-epoxy composite. Coir fibers were immersed in the solution of sodium bicarbonate with three different densities (8wt%, 10wt%, and 12wt %) for 24 hours and 120 hours. Epoxy resin was utilized as a matrix of composite. Wettability and IFSS of coir fiber-matrix adhesion were evaluated. Fiber wettability to the matrix was performed by measuring the droplet contact angle. In addition, the IFSS of coir fiber - epoxy matrix was investigated by pull out method. The surface morphology of interfacial bonding between fiber and matrix after pull out testing was evaluated by scanning electron microscopy (SEM). The results show that fiber surface wettability was influenced by sodium bicarbonate where the contact angle decrease after treatment. It suggests that good wetting of fiber and matrix. While the density of 12 wt% sodium bicarbonate for 120 hours possessed the highest interfacial shear strength of fiber-epoxy adhesion compared with other densities.
Drag aerodinamika pada kendaraan disebabkan adanya tekanan rendah dan separasi aliran di bagian belakang, yang berdampak pada menurunnya kecepatan, meningkatnya penggunaan bahan bakar, dan turunnya efisiensi kendaraan. Blowing merupakan salah satu pilihan rekayasa kendali aktif aliran yang dapat diterapkan pada desain kendaraan yang dapat mengendalikan pembentukan separasi aliran dan berefek positif berupa pengurangan hambatan aerodinamis. Penelitian ini bertujuan menganalisis pengaruh penerapan blowing terhadap pola aliran, distribusi tekanan, dan hambatan aerodinamika yang bekerja pada bagian belakang model. Dengan bantuan CFD Fluent 6.3, model uji yang digunakan adalah model kendaraan dengan sudut kemiringan geometri depan (α) 35o dan rasio terhadap model Ahmed bodi original adalah 0.17 (1:6), yang dilengkapi dengan blowing dengan kecepatan 1.0 m/s. Hasil komputasi mengindikasikan bahwa penerapan blowing dapat mengurangi pembentukan wake dan menunda separasi aliran dan dapat meningkatkan koefisien tekanan minimum pada bagian belakang model kendaraan sebesar 24.690%. Pengurangan hambatan aerodinamika diperoleh sebesar 9.583%.
Ground source cooling system (GSCS) is promising technology to serve cooling demands of buildings. This study presents a development of an open-loop GSCS for space air conditioning at Hasanuddin University Gowa campus. Experimental study was carried-out by pumping water from well of 57 m depth and flowing the water over a heat exchanger to cool refrigerant of air conditioning (AC) unit. The performance of AC unit was investigated under actual operation with various water flowrates. The temperatures of inlet and outlet water in the heat exchanger were also measured. The system operated from 11:00 until 18:00 o'clock local time with 3 (three) flowrates such as 3.6; 6.5 and 14.3 L/min respectively. In the low flowrate, the temperature of outlet water is approximately 37 o C. However, the compressor power is also increase significantly. The coefficient of performances (COPs) of the system in average are 2.9 in the low flowrate and 3.4 in the high flowrate. Also. the result shows that the utilization of GSCS is appropriated for cooling buildings in the hot climate like Indonesia.
The aim of this study was to investigate the effect of gas flow rate on the gas production rate from n-dodecane using steam reforming in-liquid plasma. A steam reforming of n-dodecane was carried out within the reactor vessel which was connected to a waveguide, an aluminum rectangular tubes that guides the propagation of electromagnetic waves with minimum loss of energy. The liquid medium used for plasma generation was n-dodecane (commercial reagent). The tip of a single electrode was positioned in the bottom center of the reactor vessel for plasma formation. The produced gas flowed through an aspirator and was trapped and collected in a water filled container. The gas production rate was measured and its compositions were analyzed using a gas chromatograph. The gas production rate by plasma with steam feeding was 1.4 times greater than that by plasma without steam feeding. The hydrogen content of the gas produced ranged from 73% to 82%. The maximum energy efficiency, as indicated by the ratio of the enthalpy difference of the chemical reactions to the input energy, was approximately 12%. The maximum hydrogen generation efficiency obtained from experiments was up to 59% higher than the efficiency of hydrogen production from electrolysis of alkaline solutions as reported in literatures.The energy payback ratio of hydrogen (EPR H2)was also calculated in order to obtain the hydrogen production efficiency.
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