Kesetimbangan Energi Termal Dan Efisiensi Transient Pengering Aliran Alami Memanfaatkan Kombinasi Dua Energi

The energy used as a dryer is usually only a single type of energy. In this case, study is conducted on the natural flow dryer system by using the chimney. This combination of energy utilization of solar energy and biomass that can be used simultaneously or one turns in accordance with the needs or circumstances. It has been tested against a dryer prototype by performing measurements on the temperature of the inlet air and exit on biomass furnace, the temperature of the inlet air and exit on the solar collector, the temperature of inlet air and exit on the drying chamber, the water content of dried material, the temperature of dried material, the surface temperature of inside and outside of wall on drying chamber, and the intensity of solar radiation. Data were collected at an interval of 30 minutes and do the processing of such data. Next made in a graphical form of thermal energy balance and system efficiency versus the time. Results obtained that: the drying time was 7.5 hours. Thermal energy balance versus the time found that the increase of energy losses lead to useful energy reduction system

Development of mesoporous activated carbons derived from brewed coffee waste for CO2 adsorption

The primary cause of rising CO2 concentrations in the atmosphere is the use of fossil fuels in motor vehicles and factory activities in industry. CO2 levels in the atmosphere can be controlled and reduced by using low-carbon energy and capturing and storing CO2. One widely used way for CO2 capture and storage is adsorption method. This method necessitates the use of an adsorbent, one of which is activated carbon. In this study, brewed coffee waste was converted into activated carbons, characterized, and tested for carbon dioxide adsorption. Brewed coffee waste was dehydrated at 105 ºC for an hour before being carbonized at 550 °C and activated at 670, 700, and 730 °C, with a 200-ml/min nitrogen injection during activation. Activated carbons with activation temperatures of 670, 700, and 730 °C were denoted as AC-670, AC-700, and AC-730, respectively. A series of TGA, SEM, and adsorption isotherm tests were used to determine the proximate components, surface morphology, and surface structure of the activated carbons produced. To assess the adsorption capacities of activated carbon on CO2, the gravimetric CO2 adsorption isotherm method was used. According to the findings of the study, increasing activation temperatures cause variable properties in activated carbon. When using an activation temperature of 700 °C, the most appropriate properties of activated carbon can be obtained. It has 425.843 m2/g specific surface area, 0.345 cm3/g pore volume, 3.423 nm pore diameter, 235.628 cm3/g nitrogen adsorption capacity, and 4.183 mmol/g CO2 adsorption performance. This study provided a simple way converting brewed coffee waste into activated carbon with excellent performance for CO2 adsorptio

Perbaikan Performa Traksi dengan Modifikasi Rasio Gigi Tansmisi

Salah satu aspek penting dalam menentukan daya saing suatu produk otomotif adalahkemampuan atau performa traksi, yaitu kemampuan kendaraan untuk melakukan percepatan,melawan hambatan angin, melawan hambatan rolling, melawan gaya tanjakan dankemungkinan untuk menarik suatu beban. Besar kecilnya traksi untuk setiap tingkat gigi sertakecepatan kendaraan yang mampu dicapai dapat dikendalikan dengan mengatur rasio dantingkat transmisi. Rasio transmisi berpengaruh terhadap besarnya torsi yang dapatditransmisikan, sedangkan jumlah tingkat kecepatannya berpengaruh terhadap kehalusanproses transmisi dan transformasi daya pada sistem transmisi tersebut. Untuk mencariperbandingan gigi antara tingkat transmisi terendah dan tertinggi adalah dengan cara progresigeometri. Dasar dari penggunaan metode ini adalah untuk mendapatkan rasio dan jumlahtingkat kecepatan gigi transmisi pada daerah kecepatan operasi mesin yang sama sehinggafuel economy pada setiap gigi akan sama. Modifikasi rasio gigi menghasilkan kurva traksidimana jarak kurva gigi yang berdekatan semakin dekat. Hal ini menunjukkan kehilangan dayawaktu pemindahan gigi transmisi semakin kecil, atau dengan kata lain kinerja traksinyasemakin baik. Perancangan rasio dengan pemasangan 6 tingkat kecepatan,menghasilkankurva traksi dengan jarak antara kurva traksi sangat dekat, berarti kinerja traksinya palingbaik.Kata kunci: Gaya traksi, rasio gigi, jumlah tingkat kecepatan, hambatan rolling One of important aspect in determining competitiveness of a product otomotif is tractionperformance, that is ability vehicle to incressing the acceleration, melawan of wind resistance,overcoming of rolling resistance, overcoming of grade resitance and possibility to draw anburden. The level of traction from gear ratio stage and also vehicle speed capable to bereached manageable by arranging ratio and number of level transmission. Transmission ratiohave an effect on to level of torque which can transmission, while amount mount its speed havean effect on to softness process the transmission and transformasi energy at the transmissionsystem. Giving for the gear ratio by progresi geometry method. Elementary from this methoduse is to get the ratio and sum up the level of speed at speed area operate for the samemachine so that fuel economy in each gear ratio will be equal. Modification of gear ratio givingthe traction curve where nearby gear ratio curve distance closer. Ratio scheme with theinstallation 6 stage of kecepatan giving traction curve with the distance of traction curve stingnear by, meaning best performance traction..Keywords: Traction, gear ratio, amount level stage, rolling resistanc