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This research presents CFD analysis of the twodimensional subsonic flow over a GOE-387 airfoil at various thickness-to-chord ratios (t/C) and chord lengths, operating at a Reynolds number of 400,000. Lift Coefficient (CL), Drag Coefficient (CD), and CL/CD are investigated. The geometry of the airfoil is created using SolidWorks and Ansys Design Modeler. CFD analysis uses Ansys Fluent at various t/C from 5% to 25%, while the chord length varies from 100 to 200 cm. It was shown that variations in chord length have an effect in the form of increases and decreases in the value of the CL and a decrease in the CL/CD ratio, which is caused by the greater length value of the GOE-387 airfoil chord. In addition, variations in the thickness-to-chord ratio parameter also CLearly influence the aerodynamic characteristics of GOE-387 airfoil. The greater the t/C, the more significant the lift and drag coefficients increase while the CL/CD ratio decreases. [ABSTRACT FROM AUTHOR]

Solar powered grain drying machines (PGTM) have advantages over fossil energy, namely they are cheap and simple. However, the main obstacle is the dependence on time and weather. To overcome these weaknesses, it is necessary to create a combined system, namely, a solar and PGTL electric drying system. This machine works during the day and continues at night using electric power. This will speed up the grain drying process without having to wait for the sun to rise. The method of supplying electrical power in the drying room is carried out directly with incandescent lamps installed on the drying racks. The amount of electrical power provided to the lamp is equivalent to the average solar energy during the day that enters the drying room, which is 400 Watts. The drying room used for research has an area of 0.9 x 1 meter and a height of 1.7 meters and is equipped with 5 shelves for placing the grain. The hot air flow in the drying room is used by a blower at 2 speeds, namely 4, 7 and 10 m/sec. The walls of the drying room are covered with aluminum foil to increase the efficiency of lamp heat absorption that can be received by the grain. The performance of an electric grain dryer (PGTL) is expressed in terms of drying efficiency or reduction in water content in the grain (Mw) and machine efficiency, ηpgel. The test was carried out at night for 5 hours with a total amount of grain of 8 kg divided into 4 shelves of 2 kg each. From the test results of the PGTL machine, it was found that the reduction in water content in grain (Mw) at air speeds of 4 m/s, 7 m/s and 10 m/s, respectively, was 7.45%, 7.9%, 9.45%, and machine efficiency respectively 20.1, 21.1% and 25.45%. [ABSTRACT FROM AUTHOR]

Many studies are being conducted to determine the optimal cooling arrangement for solar panels. One of the main issues that persists is the cooling effect used to lower the temperature of PV cells. The issue with natural convection air cooling surrounding solar panels is that it is thought to need to be more efficient in absorbing heat. It is necessary to implement effective and efficient cooling techniques. Phase Change Material (PCM) can be used as a cooling agent; the material should be chosen based on its melting point. The choice of a PCM depends on the climate and the material's thermal properties. PCM will absorb more heat throughout the melting process due to its higher latent heat than other materials. Analyzing PCM applications with nano-material addition was investigated numerically with Ansys Fluent. Pure PCM and a combination of nanomaterials were used in the cooling setup. A novel NPCM blend was made using the nanomaterials SiO2 and Al2O3. The mass fraction of the additional nanomaterial is 1%, 5%, and 10%, respectively. Viscous laminar and transient flow conditions were used as methods for this study. The aim of this study is to examine the impact of paraffin-40 combined with nanomaterials on PV cell temperature lowering. PV cell temperature is reduced to 85.98 oC by applying pure paraffin-40 cooling at a heat flux of 1000 W/m². When Al2O3 composition is added at 1%, 5%, and 10%, the PV cell temperature decreases to 59.20, 53.46, and 48.06 OC, respectively. PV cells' temperature with the addition of SiO2 at compositions of 60.95, 59.62, and 57.46 oC, respectively. Blended materials with NPCM work well for solar panel passive cooling. A higher mass concentration of nanomaterials added to the composition has a more significant cooling effect. When added as an extra nanomaterial to PCM, Al2O3 performs better at cooling than SiO2. [ABSTRACT FROM AUTHOR]

In the concept of downsizing an internal combustion engine, the turbocharger in one of the key device for reducing emissions while maintaining engine performance. Turbine as one of the main components in a turbocharger has an important role in determining the power generated by an internal combustion engine. This paper presents the development of turbine components in turbocharger and methods of turbine design optimization. In order to maximize the performance of the turbine in the turbocharger, a variable geometry turbine (VGT) is used. VGT has several variations that have been developed such as Active Controlled Turbocharger (ACT), Passive Controlled Turbocharger (PCT), Variable Nozzle Turbine (VNT), and Regenerative Electrically Assisted Turbocharger (REAT). Another thing that can be developed to maximize turbine performance is to use a double-entry turbine. The double entry turbine has the aim of saving exhaust gas energy and facilitating cylinder gas exchange. One way to produce efficient turbine performance is to replace the existing spiral casing on the turbine with a multi-channel casing (MC). The use of this multi-channel turbine reduces the best efficiency points (BEP). [ABSTRACT FROM AUTHOR]

PT. X is a company engaged in the field of Steam Power Plant (SPP) with a capacity of 2x350. With a workload of up to 24 hours a day, periodic overhauls are required for the machines in the SPP environment, one of which is the bearing which functions to withstand radial and axial loads on the C2 conveyor machine. Bearing lifetime needs to be calculated to find out the estimated useful life of the bearing so that it is easier for the company to carry out scheduled maintenance according to the job plan. Based on the results of calculations carried out using the analytical method based on ABMA (American Bearing Manufacturers Association) the results are 5.9 years worth and 6.2 years worth of results using the bearing calculator. Based on the usage duration guidelines, the results of calculations using the analytical method and the results of calculations using the tools on bearing calculator show that both results meet the minimum usage duration threshold (40,000-50,000 hours). [ABSTRACT FROM AUTHOR]

Each of Units 1-4 SLA PGU has a capacity of 400 MW and seven feedwater heaters, namely three lowpressure feedwater heaters (LPH 1, 2, and 3), a deaerator, and three high-pressure feedwater heaters (HPH 5, 6, and 7). HPH 5 in Unit 2 has experienced 30% tube plugging, which is equivalent to 480 out of 1579 tubes. Plugging is expected to reduce the performance of HPH. If the plugging exceeds the maximum limit, the HPH needs to be retubed to restore equipment reliability. Furthermore, a comparison of the performance of HPH 5 was calculated with plugging variations of 0%, 22%, and 30% when the unit was at full load. The calculation results of terminal temperature difference (TTD), drain cooler approach (DCA), and log mean temperature difference (LMTD) showed an increase with the increase in plugging in HPH. Meanwhile, the calculation of heat rate and effectiveness showed a decrease caused by the additional plugging in the HPH. The largest heat transfer occurs in the condensing zone of the HPH, where the value is around 80% to 85% of the total heat transfer that occurs. All calculations of the relationship between performance parameters and HPH plugging variations have an R-square value of more than 0.67, indicating a strong relationship. [ABSTRACT FROM AUTHOR]

Summary: The purpose of this research is to examine the performance assessment and multi‐objective optimization of a multigeneration energy systems that include power generation, cooling, and freshwater. The system under investigation is composed of a fuel cell, a multi‐effect desalination plant, an absorption chiller, a steam generator, and a thermoelectric generator. To do this, we employed thermodynamic modeling of the intended cycle to determine the optimal design points employing a genetic algorithm. Machine learning techniques have been utilized to lower the computing time and cost associated with optimization. The optimization of this cycle revealed that it is possible to increase the exergy and energy effectiveness by up to 72 and 79%, respectively while lowering the total cost rate to $ 9.23 per hour. [ABSTRACT FROM AUTHOR]

Compact heat exchanger with gas as a heat exchange medium is widely used in power plants, automotive, air conditioning, and others. However, the gas has a low thermal conductivity resulting in high thermal resistance causing a low rate of heat transfer. Therefore an improvement to the convection heat transfer coefficient is necessary. One way to enhance the convection heat transfer coefficient is to use a longitudinal vortex generator. However, the increase in convection heat transfer coefficient is followed by an increase in pressure drop. Therefore, this work aims to improve the convection heat transfer coefficient with a low pressure drop. To achieve this goal, experiments were carried out by perforating a longitudinal vortex generator with a diameter of 5 mm with variations in holes number one, two and three. Two types of longitudinal vortex generators are compared. The experimental results show that the convection heat transfer coefficient for the case of perforated concave delta winglet vortex generator is only decreased by 1% from that without a hole, while the pressure drop is decreased by 11.6%.

Various heat sinks have been widely researched to get a better performance design. This research aims to study the effect of fin longitudinal spacing and Reynolds number on heat sink performance at an oblique angle of 45 degrees. This study utilizes a finite-volume computational approach to determine the performance and details of the flow on the heat sinks. The calculations are conducted on fin spacing between 0.3 mm and 1.5 mm in the Reynolds number of 6,470 to 19,410. It was found that the fin longitudinal spacing significantly affects the performance of heat sinks for various Reynolds numbers, where the larger the spacing, the higher the Nusselt number. Based on this study, it can be concluded that it is necessary to determine the optimal fin longitudinal spacing in the design of the oblique heat sink. [ABSTRACT FROM AUTHOR]

The wind turbine airfoil's aerodynamic performance aerodynamics become essential for the wind turbine. This study aimed to obtain the effect of freestream turbulence intensity of wind turbine airfoil NACA 4415 using a 2D numerical method. Here, the turbulence intensity varied from 0.1% to 10% at Reynolds number 216,000 and by changing the angle of attack from -4 to 24 degrees, having a chord length of 0.153 m. The finite volume method was used in this study. It was found that the free-stream turbulence intensity can reduce the values of CD, CL, CP, and CL/CD but has insignificant effects on the wake area behind the airfoil. The decrease in airfoil efficiency observed was caused by the boundary layer flow disruption, which reduced the total pressure coefficient on the airfoil surface. Likewise, the intensity of turbulence can reduce boundary layer thickness. Finally, the freestream turbulence controls airfoil performance. [ABSTRACT FROM AUTHOR]

Train is the main means of land transportation used almost all over the world, including Indonesia. This means of transportation has multiple comparative advantages, is low in pollution, saves land and energy, and is mass in nature. The train is currently a means of transportation that is in great demand by the public. When compared to other means of transportation, trains are considered to be more economical, orderly and safe. One of the most important factors in driving safety is the need for effective brakes. Namely brakes that can be operated to slow down or stop a vehicle with the shortest possible braking distance under various travel conditions for a short period of time without compromising the stability of the vehicle. Most of the trains in the world are equipped with a braking system that uses compressed air as a force to push the blocks to the wheels or the bearings to the discs, also known as an air brake system. The braking system on the train is very important, therefore proper maintenance is needed. With the aim of increasing reliability, proper maintenance systems are needed to minimize downtime. Weibull is an appropriate method to determine which includes critical and non-critical parts and is often used in determining the level of failure or damage from the data pattern formed. The results obtained from testing 1 unit of the Air Brake System using the Weibull Method have the same 4 critical components, namely the Brake Cylinder, Brake Coupling, Isolating Cock, Distributor Valve. MTTF values of Brake Cylinder, Brake Coupling, Isolating Cock, Distributor Valve are 285 hours, 405 hours, 589 hours, 835 hours. The reliability values of Brake Cylinder, Brake Coupling, Isolating Cock, Distributor Valve are 43%, 41%, 49%, and 46%, respectively. Periodic Maintenance obtained based on the hour meter (HM) of each Air Brake System [ABSTRACT FROM AUTHOR]