Malaysian Journal on Composites Science and Manufacturing

Experimental and Numerical Study of Conical-Shaped Pin Finned Heat Sink with PCM Material

Sharzil Huda Tahsin — 2024-07-29

Many researchers have recently become interested in phase change material (PSM) for passive cooling of electronic equipment. The performance of PCM is enhanced by using fins as thermal conductivity enhancers (TCE). For a heat flux of 20,000 W/m², three-dimensional numerical (transient) analyses were conducted for pin (Circular) and conical-shaped fins with and without holes and dimples on the surfaces to investigate the heat transfer by natural convection. Paraffin wax was used as the PCM material within the fins' spaces by keeping 9% volume of the fins and 91% volume of PCM of the total space above the base plate. The transient heat transfer performance of fins is observed for 20 minutes. Surface areas, temperature curves, liquid fraction curves, and theta versus Fourier number curves were compared to analyze the effect of fins of different shapes on the heat transfer rate. Conical-shaped fins with dimples and holes showed the best cooling performance with a 4.6% increment of heat transfer compared with conventional pin (circular shape) fins. With and without PCM, conical fins were subjected to experimental investigation for 20 minutes. Mild steel was the heat sink material, and paraffin wax was the PCM material. Heat flux of 4000 W/m² was given to the heat sink’s base by a heater. The acrylic glass was used for insulation. The temperature was recorded for nine fins at different heights. In the experiment, the case with PCM gave 5% to 8% better cooling performance than the case with air. The study shows that using conical fins with dimples and holes (a unique fin shape) in PCM-based heat sinks can produce superior thermal performance compared to traditional (circular-shaped) pin-fins.

Effect of Nanomaterials on the Mechanical and Morphological Properties of Jute-GFRP Hybrid Nanocomposites

Sanaul Rabbi — 2024-07-29

Nanocomposites have garnered significant attention both within the realms of science and industry over the past decade due to their exceptional attributes, such as improved mechanical and thermal properties, gas permeability resistance, optical clarity, electrical conductivity, magnetic responsiveness, and flame-retardant characteristics. This study comprehensively investigates the influence of nano Al₂O₃, ZnO, and TiO₂ on the mechanical and morphological traits of jute-glass fiber reinforced plastic (GFRP) hybrid composites. Employing a deliberate inclusion of 3% weight of each respective nano filler, the research scrutinizes the tensile and flexural strengths of the hybrid nanocomposites. The fabrication of specimens was accomplished through the hand lay-up method, ensuring precision and consistency. The structural integrity and failure mechanisms of the composite specimens were meticulously examined through the utilization of Field Emission Scanning Electron Microscopy (FE-SEM). The FE-SEM images vividly depict intricate details, showcasing discernible features such as fiber pull-outs, breakages, voids, and internal cracks on the fractured surfaces. The tensile strength of the hybrid nanocomposites has been higher at 3% nano ZnO addition, and flexural strength has been higher at 3% nano TiO₂.

Fabrication and Characterization of Rice Husk Ash Reinforced Aluminium Matrix Composite

Touhid Hasan — 2024-07-29

Aluminium matrix composites (AMCs) are renowned for their exceptional properties, including low density, high specific strength, high thermal conductivity, and abrasion resistance, making them ideal for advanced structural, automotive, and aerospace applications. However, the challenge of finding cost-effective and environmentally friendly reinforcement materials remains. Rice Husk Ash (RHA), an often-discarded by-product of rice milling, presents a viable solution. Its utilization in AMCs repurposes waste, reduces environmental impact, and offers an economically viable alternative to conventional reinforcements. This paper explores the use of RHA as a reinforcement in aluminium matrix composites, with varying concentrations of 3%, 6%, and 9% by weight prepared through sand casting. Tensile, compressive, impact, and hardness tests were conducted, and it was found that increasing the RHA content enhances the mechanical properties of the composites. Specifically, tensile strength increases by 10.57%, 16.83%, and 46.26%, and compressive strength by 17.17%, 27.81%, and 40.45% for 3%, 6%, and 9% RHA reinforcement, respectively, compared to base samples (pure aluminium). Significant improvements in Rockwell hardness and impact energy absorption were observed, with a maximum increase of 55.26% and 70.63% for the 9% RHA reinforcement. This study demonstrates the potential of RHA-reinforced AMCs to surpass the mechanical properties of pure aluminium, contributing to the circular economy by transforming rice husk waste into a valuable composite material for diverse structural applications.

Numerical Analysis of Combustion and Emission Characteristics of a Diesel Engine Fueled with 40Butanol/60Diesel Blended Fuel

Anik Biswas — 2024-07-29

As the energy requirements of power producing systems increase, fossil fuels are becoming rare worldwide. Diesel engines are a common and efficient source of power generation. Nonetheless, several national and international bodies impose restrictions on diesel engine emissions for the environmental safety. So, to reduce the harmful diesel engine emissions, some steps should be followed which include lowering emissions and increasing performance. Butanol is a well-known biofuel which has comparatively lower emission characteristics and higher performance compared to diesel. Blending butanol with diesel can increase the performance and improve the emission characteristics of a diesel engine. A butanol/diesel blend (D60B40) is introduced to a single-cylinder, four-stroke, direct injection diesel engine. The combustion properties, and emissions are examined in this study using ANSYS Forte software. Effects of different SOI or start of injection (30, 26, 22, 18 degree BTDC) are checked. Results shows that early injection leads in greater temperatures, pressures, and heat release rates, which all contribute to a reduction in CO and UHC emissions but costs more NOx emissions. Combustion efficiency is 2.66% higher for 30 degree BTDC than 18 degree BTDC. Thermal efficiency shows 0.2% increase for 18 degree BTDC due to low wall heat transfer loss. NOx emission is 2.983 g/kWh for 30 degree BTDC where 18 degree BTDC had only 0.544 g/kWh. In order to reduce the NOx emission due to increasing blend ratio and advanced SOI, exhaust gas recirculation (EGR) is also investigated (0%, 10%, 20% & 30%) for D60B40 at 30 degree BTDC. At 30% EGR, the investigation reveals an improvement in emission characteristics, with NOx emission of 0.169 g/kWh which was about 90.5% lower than D100. The CO emission increases from 1.485 g/kWh to 5.345 g/kWh which is about 4 times more than 0% EGR. By using a higher butanol/diesel blend of D60B40 with early injection at 30 degree BTDC and EGR rate of 30%, it is feasible to satisfy the standards of many national and international organizations and improve combustion performance.

Investigation on the Effect of Process Parameters on Mechanical Properties of Vetiver Fiber Reinforced LDPE Composites

Haydar Zaman — 2024-07-29

Natural fibers (NFs) are extensively used for the ecological concern of synthetic fibers. The benefits of NFs over man-made fibers are their easy accessibility, renewability, lightweight, biodegradability, high specific features, and low price. The key reasons for affecting the features of the composite are the length and content of the fiber and the time of treatment of the fiber. Consequently, the prediction about the optimal fiber length, fiber content and treatment time becomes important, so that composites with optimal mechanical properties can be prepared. The current study narrates an experimental investigation on the effect of process parameters, namely fiber condition (untreated and sodium dodecyl sulfate (SDS) treatment), fiber sizes (3, 5, and 7 mm), fiber contents (10, 20, and 30 wt%), and treatment time (2, 4, and 6 h) on vetiver fiber (VF)-reinforced low-density polyethylene (LDPE) composite. The VF-reinforced LDPE composites have been developed by hot compression molding method and then characterized by mechanical properties (e.g., tensile strength, tensile modulus, compressive strength and modulus, impact strength, and fracture toughness) and scanning electron microscopy (SEM). The results showed that the composites’ tensile, compressive, impact properties and fracture toughness increased with increasing fiber size, fiber percentage, and treatment time. Afterwards, mechanical properties decreased by a certain size, percentage, and treatment time. SDS-treated VF-reinforced LDPE composite samples produced better tensile, compressive, and impact properties compared to the untreated composites. The composites reinforced with 20 wt% fiber content, 5 mm in length and 6 h showed the best tensile, compressive, impact properties and fracture toughness. The SEM study revealed that the SDS-treated fiber composite confirmed the homogeneous dispersion rather than the untreated composite. The composite properties reveal that VF can be a good candidate for polymer reinforcement.