This research explains the role of NaOH and bio-activator from papaya latex in the synthesis of carbon nanoparticles from rice husks in a water medium to produce fullerene-like polytype of SiC. The process begins with the pyrolysis and then the high energy milling (HEM) process followed by dispersion of NaOH and coagulation of bio-activator. The HEM process creates residual stress which produces nanocrack. NaOH dissolved into ions which activate dipole force to create dipole moment on the tip of nanocrack and become the trigger of nanocrack dispersion. The crack dispersion breaks carbon into nanoparticles having polar electrical charge so that they are dispersed homogeneously inside the water. Bio-activator then continues to perform catalytic building molecular chain as a bridge connecting pole sides of carbon nanoparticles with the bonds of van der Walls. Catalytic performance causes the coagulation process of a nanoparticle to occur which resembles the morphological structure of fullerene-like polytype of SiC with the size of 20 up to 100 nm.
Produksi plastik global meningkat selama bertahun-tahun karena banyaknya aplikasi plastik di banyak sektor. Permintaan terus menerus dari plastik menyebabkan akumulasi limbah plastik di TPA menghabiskan banyak ruang yang berkontribusi terhadap masalah lingkungan. Meningkatnya permintaan plastik menyebabkan pelepasan minyak bumi sebagai bagian dari bahan bakar fosil yang tidak terbarukan karena plastik adalah bahan berbasis minyak bumi. oleh karena itu dalam penelitian ini akan dilakukan studi terhadap karakteristik pirolisis, material Sampah plastik PET dengan katalis alam Klaten, Jawa Tengah, Indonesia. Dari hasil proses pirolisis menunjukkan bahwa jenis bahan baku sangat mempengaruhi hasil produk dan kualitas produk cair dan padat Sampah plastik PET menghasilkan fraksi cairan tertinggi. Paduan katalis mengurangi fraksi cairan dan meningkatkan fraksi gas. Selanjutnya, sampah plastik kotamadya menghasilkan produk dengan nilai lebih tinggi dari pada produk biomassa sampah plastik bisa digunakan sebagai bahan bakar alternatif.
This study aims to utilize the tobacco crop residue to generate a high economic value for the energy sector. In general notion, tobacco crop is burned as a conventional fuel at low prices; however, in this research, tobacco crop residue was processed through pyrolysis in the form of pyrolysis products (liquid and solid yields) providing a promising alternative fuel fulfilling the standardized fuel properties. The pyrolysis was conducted at a laboratory-scale real pilot plant experiment at a fixed bed reactor and was operated at temperature of around 350 °C to 650 °C for 2 hours to navigate the most optimum product. Further, the products comprising char (solid yield) and tar (liquid yield) were investigated by measuring their properties, which include heating value, flash point, viscosity, density, and char yields’ morphology. The measurement results indicated that the heating value of tobacco crop residue from pyrolysis process significantly escalated to 300% compared to that of tobacco crop residue before pyrolysis process. Similarly, several tar properties indicated the liquid fuel standard such as kerosene. Additionally, another product in the form of solid yields is proved to be utilized as a smart material besides having a higher heating value over coal, due to the high-quality carbon specifications. However, further processing is encouraged to navigate the possibility of solid yields into activated carbon.
One of the latest development of absorber plate in solar still application is the implementation of porous media.This study aims to analyze the effect of aggregate's pore size and type towards the capillary-driven fl ow and evaporation process in porous media. In order to enhance the evaporation process five different types of porous media had been chosen, namely concrete consisted river sand with the particle size of 0.125 and 0.250 mm, ferrous sand concrete with particle size of 0.125 and 0.250 mm, and natural stone as the comparison material. Top side of the specimens was exposed in a heater with 18.2 W, 27.3 W and 36.4 W. The bottom side of specimen was exposed in seawater which fl owed capillary and evaporated. The value of thermal conductivity and porosity in porous media greatly affect the temperature distribution caused by the heat transfer process. Specimens with smaller particle size has a higher thermal conductivity which resulting in a larger heat transfer rate. Concrete with ferrous sand as aggregate has a better heat transfer rate than river sand specimen. The largest heat transfer rate obtained in concrete with 0.125 mm ferrous sand with the value of 0.256 W, 0.402 W and 0.524 W in every power addition. The rate of mass transfer value equals to the rate of evaporation that occurs and strongly depends on the capillary force of each specimen. The evaporation rate data is proportional to the heat transfer rate of each specimen. However the natural stone specimen has a higher evaporation rate than expected due to better interconnectivities between its channels.
Increasing the temperature of inlet water is one way to increase solar distillation efficiency. Heat recovery using double glazing is a more straightforward way to raise the temperature of inlet water. In previous studies, the incoming water temperature was raised using additional equipment such as a solar water heater collector or utilizing the heat of wastewater from another water distillation system. The earlier studies' technique caused solar water distillation to be complicated, and the manufacturing cost was expensive. Heat recovery is a process of utilizing heat condensation of water vapor to increase the inlet water temperature. In conventional solar distillation, condensing heat is not used and wasted into the environment. Double glass is two glasses arranged in parallel, one on the top of the other. The distance between the glasses is 2 mm. The bottom glass is a 1 m2 distillation cover glass. Water flows between the bottom glass and the top glass before entering the distillation model. The inlet water receives heat condensation so that the temperature rises. The increase in temperature causes heat loss to decrease and leads to efficiency improvement. This study aims to reveal the effect of heat recovery using double glazing to improve solar distillation efficiency. The study was conducted with laboratory experiments and simulations. The thickness of the bottom and top glass and the top glass area influence the heat recovery process. This study used two variations of glass thickness, namely 3 mm and 5 mm. The area of the top glass was varied by 0.1, 0.5, 0.7, and 1.0 m2. The maximum efficiency improvement compared to distillation without heat recovery obtained is 39.6 % with a glass thickness of 3 mm and 51.0 % with a glass thickness of 5 mm achieved in the variation of the top glass area of 0.1 m2
This study investigated the effects of two additive polarities: polar (eugenol) and nonpolar (limonene) additives blended into n-heptane and low-octane gasoline. These compounds were chosen due to their unique molecular structure characteristics which influences the exhaust emissions. The physicochemical properties, fuel consumption, and exhaust gas emissions of a single-cylinder gasoline engine were measured. Four fuel blends were created by blending eugenol and limonene on a volumetric basis, n-heptane-eugenol (NHE), n-heptane-limonene (NHL), low-octane gasoline-eugenol (GE), and low-octane gasoline-limonene (GL). Tests were conducted on a single-cylinder gasoline engine. The exhaust gas emissions were analyzed using gas chromatography, and the role of each additive substance in the formation of carbon monoxide (CO), unburned hydrocarbon (HC), residual oxygen (O2), and carbon dioxide (CO2) emissions was validated using Hyperchem simulation and gas chromatography mass spectrometry. Owing to differences in the molecular structure and energy content of the two additives, the fuel consumption of NHE-fueled vehicles increased by 19.69% compared to NHL, whereas GE decreased by 32.15% compared to GL. Owing to the presence of oxygen atoms and low binding energy, blending eugenol with n-heptane and low-octane gasoline significantly reduced CO by 1.87% higher than limonene. However, eugenol's aromatic structure can only reduce 14.45% of HC emission, while limonene, with its dynamically moving electrons and nonpolar properties can reduce up to 18.24%. It was discovered that the two additives could improve the quality of exhaust gas emissions.
In the coastal areas, there are found many cases of clean water crisis; the most reasonable solution is to use the solar still from salty seawater.Sea salt concentration levels vary widely in each region depending on ecological conditions and materials carried by the river.This study aims to analyze the effect of salinity and radiation intensity towards the evaporation rate.Several parameters, such as the difference in the mass of the specimen, surface temperature, and evaporation rate were observed.The evaporation rate data shows that concrete with ferrous sand aggregate (particle size of 0.125 mm) has the highest value in which the thermal conductivity value of this specimen is of the highest value as well.Higher salt addition and radiation cause the temperature value that each specimen generated to become higher.Therefore, the FS125, which is concrete with 0.125 mm ferrous sand aggregate, has the best capability of porous media in the absorbent plate of solar still application.
Tujuan dalam penelitian ini adalah untuk mengetahui pengaruh variasi derajat pengapian terhadap kadar emisi gas buang CO, CO2, O2 dan HC pada motor bakar 6 langkah berbahan bakar etanol. Metode penelitian ini adalah eksperemental langsung dengan menguji pada objek yang dituju. Pengujian dilakukan pada motor 6 langkah berbahan bakar etanol dengan variasi sudut pengapian 240,260 dan 280. Setiap variasi di uji pada interval putaran 600 dari 2400 sampai 7200. Hasil penelitian menunjukan Sudut pengapian mempengaruhi kadar emisi gas buang CO, CO2, O2 dan HC yang di hasilkan pada pembakaran motor 6 langkah menggunkan bahan bakar etanol.Semakin maju derajat pengapian maka kadar emisi gas buang CO2 dan O2 semakin meningkat dan sebaliknya kadar emisi gas bunag CO dan HC semakin menurun.Sifat ethanol yang termasuk oxygenated fuel menyebabkan menghasilkan kandungan O2 yang lebih tinggi.
Visualization of secondary flow behavior were carried out for the laminar flow (Re = 81) in a sharp-edged and rounded-edged 90° T-junction with an inlet flow perpendicular to both inline outlet flows orientation with a bifurcation ratio of 0.5. Particles were added to the fluid. The fluid was salt solution for density similarity with the particles, leading to eliminate the bouyance effect. Static pressures were measured at the inlet and one of the outlet channels by a U-manometer. The result shows that the rounded edge affected the recirculation secondary flow area and position leading to the reduction of the head loss. The image of the secondary flow demonstrates that a T-junction with the rounded edge with a rounded-edge radius ratio of 0.5 had a broader bifurcation area and a smaller secondary flow occupation area in the outlet channel, as compared to the sharp edge. The decreasing head loss ratio was 51 %. At rounded-edge radius ratio of 0 up to 1.5 part of secondary flow was located in the bifurcation area and the outlet area, whereas at rounded-edge radius ratio of 2 and of 2.5 it was located completely within the bifurcation area. Changing rounded-edge radius ratio from 1.5 to 2 reduced the head loss ratio up to 49.72 %.
This study indentified the tar yield of pyrolysis of mahogany wood. The produced tar would be analyzed using GC-MS (Gas Chromatograph-Mass Spectrometry) to understand their chemical properties affected by temperature pyrolysis. It would be identified if the elements are flammable matters or not. It is due to the fact that the yields of pyrolysis desire the flammable matters as much as possible as a biofuel. The experiment was conducted at a fixed bed reactor. The needle particle of mahogany wood was used as the pyrolysis feedstock having weight of 200 gram, sizing of mesh 20 hm, and containing 2% moisture content. The variations of pyrolysis temperature influencing the mahogany wood decompositions are 250°C, 350°C, 450°C, 500°C , 600°C, 700°C and 800°C. The pyrolysis was carried out during 3 hours almost without Oxygen. The result of tar yields show that a getting higher of the pyrolysis temperature caused the volume and mass of tar formed by condensation in cold trap would increase up to 500°C and then decrease. The increasing of tar yields would also increase some acetic acid compounds and reach a peak at 350°C in which the acetic acid compound is a flammable substance. From the GC-MS results, it was also presented that at any pyrolysis temperatures, the amount of the flammable tar compounds were higher than the unflammable one. It can be interpreted that the tar yield is very potential as liquid fuel (bio-oil) because the main elements of tar is acetic acid having flash point (flash point) equal to 39°C.
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