Numerical Analysis of Heat Transfer Enhancement in Wavy Trapezoidal and Rectangular Microchannels

This study presents a comprehensive numerical investigation of heat transfer enhancement in microchannels with varying geometries, specifically focusing on wavy microchannels with trapezoidal and rectangular cross-sections. Water is used as the working fluid, and silicon is selected as the solid wall material. A three-dimensional conjugate heat transfer model is developed by solving the steady-state Navier–Stokes and energy equations using the finite volume method in ANSYS Fluent, with the SIMPLEC algorithm employed for pressure–velocity coupling. The analysis examines the influence of cross-sectional shape and wall waviness on thermal performance, while maintaining a constant hydraulic diameter across all configurations. Eight different geometries, including smooth and wavy versions of rectangular and trapezoidal cross-sections with varying top-to-bottom width ratios (0.075–0.055 mm), are evaluated over a Reynolds number range corresponding to inlet velocities of 0.5–4.0 m/s. Results show that wavy microchannels significantly enhance heat transfer compared to their smooth counterparts. For instance, at 4 m/s, the Nusselt number for the wavy rectangular microchannel reaches 9.48, compared to 7.19 for the smooth rectangular configuration, representing a 32% enhancement. Similarly, the wavy trapezoidal channel with a top width of 0.18 mm achieves a maximum Nusselt number of 9.25, compared to 7.19 for its smooth equivalent, indicating a 29% improvement. Additionally, the Nu/Nu₀ versus Re plots reveal a consistent trend of increased heat transfer due to wall waviness across all geometries, with negligible influence from cross-sectional shape when hydraulic diameter is kept constant. The study demonstrates that incorporating wavy structures into microchannel designs significantly improves thermal performance with minimal increases in pressure drop, and that the effect is driven more by wall geometry than by cross-sectional shape. These findings provide valuable insights for the development of compact and efficient microchannel heat sinks for electronic cooling applications

Effect of Coconut Fiber and Coconut Shell Charcoal Composition on the Properties of PVC-Reinforced Composite Brake Pads

The increasing concern over the health hazards associated with asbestos-based brake pads has driven the development of eco-friendly alternatives using natural fiber-reinforced composites. This study aims to fabricate and evaluate a sustainable brake pad material using coconut fiber as reinforcement, coconut shell charcoal powder as filler, and polyvinyl chloride (PVC) as the matrix. The composite was manufactured using the hot press method at a temperature of 180°C and a pressure of 7 MPa, conditions selected to optimize resin curing and interfacial bonding. A key focus of this research was to investigate the effect of solvent volume (cyclohexanone) used in the PVC resin preparation on the mechanical properties of the resulting composites. Three composite formulations were prepared with a constant composition of 70% coconut fiber, 5% charcoal powder, and 25% PVC resin, but with varying amounts of cyclohexanone solvent (200 mL, 150 mL, and 100 mL). The results revealed that reducing solvent content led to higher resin viscosity, which improved matrix–fiber bonding and increased both tensile strength and surface hardness. The optimal formulation—PVC Resin 3 with 100 mL of solvent—achieved a maximum tensile strength of 7.7 MPa and Shore D hardness of 72.2 HD, both of which meet the SAE J661-1997 standards for brake pad materials. This study confirms that solvent content is a critical factor influencing the density, strength, and durability of the composite. The findings support the feasibility of utilizing coconut-based agricultural waste in producing environmentally friendly brake pads with adequate mechanical performance

Enhancing The Formability of SS304 in ISF via Pre-Heating Treatment Strategies

The increasing demand for lightweight yet high-strength components in the automotive and aerospace industries has accelerated interest in Incremental Sheet Forming (ISF) as a flexible, dieless, and cost-effective manufacturing process, particularly for low-volume and customized production. Unlike conventional forming processes that rely on expensive dies, ISF offers greater geometric flexibility and rapid prototyping capabilities. However, its broader industrial adoption remains limited due to persistent challenges such as poor surface finish, springback, and restricted formability, especially when forming hard-to-deform materials like Stainless Steel Grade 304 (SS304). This study investigates the influence of customized heat treatment on the formability and deformation quality of SS304 sheets formed via ISF. Sheets were subjected to preheating at controlled temperatures ranging from room temperature to 700°C, followed by dieless forming using a CNC machining center equipped with a hemispherical tungsten carbide tool. Key process parameters, including a step size of 0.3 mm, a feed rate of 180 mm/min, and a tool speed of 500 mm/min, were maintained throughout forming. Comprehensive mechanical and microstructural analyses, including tensile testing, surface roughness evaluation, and optical metallography, were performed. Results revealed significant improvements in formability: ductility increased from 24.28% to 65%, and surface roughness (Ra) decreased from 9.7993 µm to 5.4809 µm after annealing at 700°C and tempering at 500°C. Microstructural analysis confirmed grain refinement and carbide dissolution, contributing to improved plastic flow and reduced surface defects. Integrating controlled heat treatment with ISF significantly enhances forming capabilities, surface quality, and geometric precision of SS304, making it a viable solution for manufacturing complex, high-performance components. These findings provide valuable insights for developing more efficient, defect-minimized, and adaptable forming strategies suitable for advanced manufacturing industries

Performance Analysis of Centrifugal Pumps Before and After Wear Ring Restoration

A pump is a mechanical device used to move fluids from a lower elevation to a higher one. In general, pumps are classified into two types: positive displacement pumps and non-positive displacement pumps. Centrifugal pumps fall into the latter category and operate by converting mechanical energy into kinetic energy to transport fluids. A centrifugal pump consists of several key components, including the casing, shaft, bearing, coupling, and impeller. In the case of closed impeller-type centrifugal pumps, wear rings (wearing components) are installed to provide a clearance between the impeller and the casing, preventing physical contact during operation. The size of this clearance significantly affects pump performance. Wear ring damage can result from mechanical wear, corrosion, cavitation, and fatigue, leading to performance losses such as reduced flow rate, lower pressure, and decreased efficiency. This research aims to analyze the effect of wear ring damage on the performance of a centrifugal pump by comparing operational data before and after repair of the wearing components. The performance parameters evaluated include pump head, pressure, hydraulic power, motor power, and overall efficiency. Data were collected through a structured procedure consisting of preparation, testing, measurement, and analysis. Prior to repair, the pump operated with a wear ring clearance of 1.2 mm, resulting in an average efficiency of 8.5% and a flow rate of 0.000646 m³/s. After the clearance was restored to 0.43 mm, the average efficiency increased to 15.5%, with a corresponding flow rate of 0.000932 m³/s. These results demonstrate that maintaining wear ring clearance within recommended standards significantly improves pump performance, highlighting the importance of regular maintenance and timely component repair

Use of Hibiscus rosa-sinensis as a Green Corrosion Inhibitor for Valve Materials in RO Water

Valves are mechanical devices that regulate the flow of oil and gas fluids and are typically constructed from materials that are heat-resistant, corrosion-resistant, and capable of withstanding high pressure. However, observations from valve manufacturing companies in the Banten area have shown that valve components made from medium carbon steel ASTM A105N are susceptible to corrosion during hydrotesting, particularly when using reverse osmosis (RO) water as the testing medium. This corrosion can degrade product quality before delivery to customers. To address this issue, this study investigates the use of Hibiscus rosa-sinensis as a green corrosion inhibitor. The objective of this research is to evaluate the corrosion rate, inhibitor efficiency, and surface morphology of ASTM A105N valve materials using Hibiscus rosa-sinensis in RO water media, with varying inhibitor concentrations and immersion durations. The electrochemical methods used include Potentiodynamic Polarization, Electrochemical Impedance Spectroscopy (EIS), Chronoamperometry, and Scanning Electron Microscopy (SEM). Results from the corrosion rate tests indicated that the highest inhibitor efficiency—59.04%—was achieved at 24 hours of immersion with a 2 g inhibitor concentration. This condition also yielded the lowest corrosion rate of 1.2231 × 10⁻² mm/year and the lowest corrosion current (Icorr) of 3.2601 × 10⁻⁶ A/cm². Chronoamperometry testing confirmed these findings with the lowest electric charge value of 0.0125 C. SEM analysis further revealed a more uniform and homogeneous protective coating on the metal surface under these conditions. Based on these results, Hibiscus rosa-sinensis demonstrates promising performance as a green corrosion inhibitor and is recommended as an additive in RO water for valve hydrotesting. This study highlights the potential of environmentally friendly and cost-effective inhibitors in reducing corrosion risk in valve materials

Enhancing Homogeneity and Particle Size Reduction in Coffee–Creamer Mixtures Using Fluidized Bed Mixer

This study investigates the application of a fluidized bed mixer to improve the homogeneity, particle size distribution, and moisture reduction of coffee and creamer powder mixtures. The research focuses on three types of coffee particles—Type A (145 μm), Type B (100 μm), and Type C (50 μm)—which were mixed with creamer in a weight ratio of 1:0.7. The mixing process was conducted using a prototype fluidized bed mixer with a capacity of 1,000 grams and a blower speed range of 2,800–3,000 rpm. After 10 minutes of mixing, significant reductions in particle size were observed: Type A decreased by 20–30%, Type B by 10–15%, and Type C by 5–10%, with creamer particles also experiencing a 15% reduction. Moisture content dropped from 10.63% to 8.5%, demonstrating the system’s dual function of mixing and drying. Microscopic analysis revealed a uniform particle distribution with minimal agglomeration or segregation, confirming the effectiveness of the fluidized bed mixer in achieving a homogeneous blend. These findings underscore the potential of fluidized bed technology in improving the quality, stability, and handling properties of powder-based products. The results have important implications for instant beverage production, food formulation, and broader powder processing industries, where consistent product performance is essential

Review: Optimizing Plastic Injection Processes for Enhanced Quality and Sustainable Manufacturing

In the automotive world, plastic products are components that cannot be separated. Almost all automotive products use plastic because it is easy to produce, and the price is relatively cheap compared to other materials. For applications such as covers, the demand on plastic surface quality are higher than for different uses. Therefore, a lot of costs are incurred to achieve this quality. However, ongoing efforts have decreased the time and expense of developing plastic molds. Many researchers have conducted studies to improve the quality of these products. This review consolidates several research articles on optimizing plastic injection processes to reduce defects and improve product quality. Techniques such as Taguchi Method, Response Surface Methodology (RSM), Artificial Neural Networks (ANN), and Finite Element Method (FEM) were evaluated in this research. This review highlights the importance of process parameters such as melt temperature, injection pressure, and cooling time, as well as the role of digital simulation in designing efficient and sustainable molds. The results of the study show that in several studies, defects often occur in the product without carrying out the optimization process. Still, the Taguchi and ANOVA methods can reduce the weld line and sink after optimizing the process parameters, such as melting temperature, injection pressure, cooling time, and injection speed. Mark up to 30%. These findings highlight the potential of these techniques to significantly improve product quality and support more sustainable manufacturing practices in the plastic injection molding industry

Development of Teak Wood Powder Epoxy Composite as an Alternative Material for CVT Motorcycle Roller Weight

This study developed an environmentally friendly composite material for use in roller weights of Continuously Variable Transmission (CVT) systems in motorcycles. The composite, made from teak wood powder (Tectona grandis L.F.) and epoxy resin, was formulated as an alternative to conventional PTFE (Polytetrafluoroethylene), which is less environmentally sustainable. The composite was fabricated using the hot-press method, with variations in the teak-resin composition ratios (60:40, 70:30, and 80:20) and hot-press temperatures (160°C, 170°C, and 180°C). The results showed that the composite with a 60:40 composition at 180°C and 20 bar pressure achieved the highest tensile strength of 25 MPa, exceeding that of conventional roller weight material (23 MPa). Tensile testing was conducted in accordance with ASTM D3039 standards. In addition to its superior mechanical performance, the material also utilizes biomass waste and has the potential to reduce production costs. These findings demonstrate that teak wood powder composite is a viable candidate for strong, durable roller weight applications and supports the development of more sustainable automotive components

Handling and Stability Analysis of an Autonomous Vehicle Using Model Predictive Control in a CarSim–Simulink Co-Simulation Environment

Cars are a prevalent mode of transportation for both people and goods, with B-class hatchbacks being particularly popular in Indonesia. However, road traffic crashes remain a major concern, contributing millions of deaths annually, primarily due to human error. Autonomous vehicles offer a promising solution to mitigate these issues by reducing reliance on human control. In particular, Level 3 autonomous vehicles enhance road safety, enable independent mobility, reduce traffic congestion, and allow drivers to engage in non-driving tasks. This study proposes an autonomous vehicle model that employs a trajectory tracking approach using Model Predictive Control (MPC), a robust and widely adopted control strategy in autonomous systems. A three-degree-of-freedom (3-DOF) vehicle dynamic model was developed and analyzed through co-simulation using CarSim and Simulink to evaluate its performance during a double-lane change maneuver. The simulation results demonstrate that the vehicle accurately follows the reference trajectory and exhibits excellent dynamic performance. The roll angle remained consistently low, ranging between 0.024 and 0.026 radians—well below the rollover threshold of 0.14 radians—demonstrating strong roll stability. The slip angle varied between –0.013 and 0.0135 radians, nearly 12 times lower than the critical limit, indicating optimal traction and directional control. Lateral acceleration ranged from –3.59 m/s² to 3.41 m/s², and yaw rate remained within –7.78°/s to 7.25°/s, both well within safe operational bounds. These findings confirm that the proposed MPC-based control framework enables precise path tracking, robust stability, and reliable handling performance in dynamic driving scenarios

Mechanical Properties Analysis of Stainless Steel 304 Linear Guide Rail Using Autodesk Inventor and MATLAB

This study investigates the mechanical properties of a stainless steel 304 linear guide rail using a combination of Autodesk Inventor and MATLAB. The primary objective is to analyze the von Mises stress distribution, displacement, and safety factor of the linear guide rail under varying load conditions, as well as to develop a model representing the relationship between stress and strain. A detailed 3D model of the guide rail was created using Autodesk Inventor, followed by finite element analysis (FEA) to evaluate stress and strain distribution across different sections of the rail. The simulation was conducted to assess the structural response under multiple loading scenarios, ensuring its reliability for real-world applications. Furthermore, a linear regression analysis was performed using MATLAB to establish a predictive model correlating stress and strain, enabling more accurate forecasting of the material's mechanical behavior. The results revealed that the maximum von Mises stress obtained from the simulation was 23.595 MPa, with a corresponding maximum displacement of 0.397 mm. The safety factor analysis confirmed the rail's structural integrity, with a minimum safety factor of 10.595, well above the failure threshold. These findings indicate that the linear guide rail meets the necessary mechanical performance requirements for its intended application