Journal of Advanced Research in Fluid Mechanics and Thermal Sciences

The Utilisation of Coconut Shell (Cocos Nucifera) as a Partial Aggregate Replacement on the Properties of Concrete in Terms of Thermal Behaviour

Alif Syazani Leman, Shahiron Shahidan, Ahmad Shahrir Md. Naziri, Bassam Tayeh — Tue, 10 Dec 2024 00:00:00 +0700

Green environments or environmentally friendly buildings have increasingly captured the attention of researchers. This concept involves the reuse of waste materials to enhance or create new products. Accordingly, this study aims to investigate the utilization of fine coconut shell (FCS) as a partial substitute for sand, focusing on its applications with varying percentages from 10% to 100% on the properties of concrete in terms of thermal conductivity. The initial phase of the research concentrated on characterizing the properties of fine coconut shell and sand using methods such as sieve analysis, laser diffraction sieve technique, specific gravity tests, bulk density measurements, scanning electron microscopy (SEM), and water absorption tests. Subsequently, the mechanical properties of fine coconut shell in concrete, replacing sand partially, were evaluated through slump tests, compressive strength tests, flexural strength tests, modulus of elasticity tests, splitting tensile strength tests, water absorption tests, and water permeability tests. The second phase of the study focused on exploring the low thermal conductivity applications of fine coconut shell concrete, assessed through thermal conductivity tests (k-value) and thermal resistance (r-value) calculations. Upon collecting data, a relationship analysis was conducted to determine the optimal percentage of fine coconut shell replacement. Using this optimal percentage, wall panels were constructed to assess heat penetration into buildings, and the temperature data was validated using Autodesk Ecotect software. The findings indicated that fine coconut shell particles were finer (≤ 600 μm) compared to sand (4.25 mm - 150 μm). In terms of mechanical properties, concrete containing fine coconut shell as a partial replacement for fine aggregate demonstrated superior performance to normal concrete. Moreover, the thermal conductivity values of specimens containing coconut shell were lower than those of normal concrete. In conclusion, the study determined that replacing 50% of fine aggregate with fine coconut shell was optimal, meeting British Standard requirements and aligning with previous research findings.

Experimental Study of the Effect of Plastic Pyrolysis Oil on the Physical-Chemical Properties of Rubber Seed Biodiesel and Diesel Engine Performance using a Mixture of Plastic Pyrolysis Oil-Rubber Seed Biodiesel-Diesel Fuel

Tue, 10 Dec 2024 00:00:00 +0700

Rubber seed oil is a potential source of biodiesel, but its utilization is still limited. From previous research studies, the addition of Rubber Seed Biodiesel (RSB) to diesel will reduce engine performance and increase BSFC but can increase emissions. At the same time, plastic waste has posed a very serious environmental challenge due to its large quantity and suboptimal processing problems. Pyrolysis is considered to be an efficient solution for handling plastic waste, because it operates at low pressure and produces Plastic Pyrolysis Oil (PPO) as fuel. The success of research on converting plastic waste into fuel can be a solution to limited biodiesel raw materials, as well as a solution for handling plastic waste. From various previous studies it is known that PPO has a higher heating value than biodiesel, but biodiesel has a higher centane number. Based on these various symptoms, it is interesting to research the use of a mixture of RSB and PPO fuels, because they are thought to complement each other. In this research, PPO was added to RSB starting at 10%, 20%, 30% and 40%, then the physicochemical properties of each mixture were examined, it was found that PPO could increase the heating value, reduce viscosity, density and acid number, reduce the cetane number and reduces the oxidation stability of RSB. To test on a diesel engine, PPO was added to the diesel-RSB mixture. The diesel portion is set at 60%, while the RSB and PPO portions are varied starting from 40% RSB 0% PPO, 30% RSB 10% PPO, 20% RSB 20% PPO and 10% RSB 30% PPO. Diesel engine performance and emissions were investigated when PPO was added to the fuel mixture. The search results show that BTE decreased by 4% when using B10P30 compared to using pure diesel, but increased by around 30% compared to using RSB40 at full load. The addition of PPO to the Diesel-RSB mixture increases CO, HC and smoke emissions, but is still lower than pure diesel emissions.

Study on Mechanical and Thermal Properties of Plasticizer with Epoxidation Waste Cooking Oil

Tue, 10 Dec 2024 00:00:00 +0700

This study investigates the mechanical and thermal properties of plasticizers formulated with Epoxidized Waste Cooking Oil (EWCO). The primary objective is to evaluate the influence of EWCO as a plasticizer on the performance of polylactic acid (PLA) composites. Epoxidation of waste cooking oil with and without catalyst (sulfuric acid) is applied before mix with PLA. PLA, a biodegradable polymer, is chosen due to its environmental benefits, but its brittleness limits its application. By incorporating varying weight ratios of EWCO (2.5%, 5%, 7.5%, and 10%), both with and without the presence of a catalyst, the tensile strength and thermal stability of the resulting composites are assessed. The mechanical properties were analyzed through tensile strength tests, revealing that the inclusion of EWCO generally decreases the tensile strength of PLA. Notably, the addition of a catalyst significantly enhances the tensile strength, demonstrating the potential of catalysts in optimizing the mechanical properties of PLA/EWCO composites. Thermal properties were evaluated a melting point and a glass transition temperature (Tg). Results indicate that EWCO influences the thermal stability of PLA, with variations depending on the presence of a catalyst and the EWCO concentration. The results in this research also shows that sulfuric acid is used as a catalyst in the epoxidation process of waste cooking oil (WCO) to produce epoxidized waste cooking oil (EWCO) the epoxide yield achieve around 85% and give shorter reaction time of 4 hours. This research contributes to the understanding of how EWCO, a sustainable and eco-friendly plasticizer, affects the mechanical and thermal properties of PLA composites. The findings of this study shows that EWCO enhances flexibility, the mechanical strength and thermal stability This study provides a foundation for future research aimed at developing optimized PLA/EWCO composites for diverse applications, promoting sustainability in material science.

Experimental Investigation of Temperature Homogeneity and Peak Temperature in a Battery Pack of Cylindrical Li-ion Cells Under Free and Forced Convection

Manmeet Singh, Sudhanshu Dogra, Ravindra Jilte — Tue, 10 Dec 2024 00:00:00 +0700

Electrical vehicles (EVs) are emerging as a suitable replacement for conventional IC engine-based automobiles because of their environmental friendliness. An EV is powered by a rechargeable battery pack usually made of Lithium-ion batteries and these batteries generate heat during their operation cycle due to exothermic reactions and ohmic effect. Thermal management of batteries is important for their safe operation and optimum lifespan. In this paper, a comparative analysis of temperature homogeneity, peak temperature and average temperature of battery pack is presented between free and forced convection-based Battery Thermal Management System (BTMS). Cells that are at higher temperature than average temperature of battery pack are more liable to fail earlier as compared to other cells of pack. Present research focuses on finding such critical cells in a battery pack consisting of twelve lithium-ion batteries. The battery pack is discharged at three different rates: 1C, 2C and 3C, and temperature of each cell is measured at regular intervals during the discharge process. The experimental results from present study revealed that free convection is better at maintaining temperature homogeneity, but peak temperatures were above 50 ̊C. Forced convection based BTMS was able to keep peak temperatures below 50˚C at 1C discharge rate but temperature homogeneity was not maintained within ideal limits of 5˚C. At higher discharge rates, the performance of both free convection and forced convection based BTMS is not within acceptable limits. Critical cells were identified to get better insight into limitations of conventional cooling systems so that better layout of battery module and better alternative methods of battery pack cooling can be developed.

Review on the Air Temperature and Humidity Produce by Solar Dryer and Potential to be Reused

Tue, 10 Dec 2024 00:00:00 +0700

This article presents a comprehensive review of recent advancements in the reuse of waste heat from solar food dryers, a strategy that holds significant potential to improve system efficiency and sustainability. Solar drying systems typically discharge air at temperatures between 40°C and 70°C, resulting in a substantial loss of free solar thermal energy up to 50% of total energy. This review introduces novel approaches to capturing and reusing this low-quality heat, including the integration of desiccant materials that can boost drying efficiency by up to 64%, and innovative designs like rotating dryer wheels, which increase effective heat gains by an average of 153%. Unlike previous studies, this article not only aggregates and analyzes field test data such as outlet temperatures, humidity levels, and heat recovery efficiencies but also identifies practical and scalable solutions for heat reuse, such as water heating, space heating, and heating nearby cold rooms. By providing quantitative results and exploring the potential for continuous 24-hour operation through advanced heat management techniques, this review offers new insights and practical guidelines for engineers and researchers aiming to make solar drying processes more energy-efficient and commercially viable. This work is particularly relevant for those interested in developing sustainable agricultural practices, as it highlights the most promising methods for reducing energy waste and enhancing the overall performance of solar dryers. The novel synthesis of existing technologies and the identification of key areas for future research make this article a valuable resource for advancing the field of solar drying.

Assessment of Photovoltaic Thermal Efficiency using Phase Change Material and Water-Channel Collector with T-Fin Design

Tue, 10 Dec 2024 00:00:00 +0700

Photovoltaic thermal systems, also known as hybrid solar panels, combine photovoltaic and solar thermal components to generate both electrical and heat energy from the sun. Despite solar energy has significant potential, conventional photovoltaic systems suffer from low efficiencies due to the wasted heat energy and high working temperature. This research aims to develop and examine the efficiency of a photovoltaic thermal system integrated with commercial phase change material (PCM) using copper T-fin absorber to increase solar energy conversion efficiency. The research involved fabricating aluminium packets for commercial PCM, filling fabricated packets into a developed photovoltaic thermal system with T-fin absorber, and conducting final experiments under three different water flow rates for each of three different irradiance levels under solar simulator with 30 minutes run for each test. The final experiment assessed temperature difference, electrical efficiency, thermal efficiency, and overall efficiency. At 800 W/m² and 90 l/h, the highest temperature drop was 11.20°C. The highest electrical efficiency of 8.0% was achieved at 800 W/m² and 90 l/h. The highest thermal efficiency was 72.5% at 400 W/m² and 90 l/h. The highest overall efficiency of 79.8% at 400 W/m² and 90 l/h for the T-fin absorber. These results concluded the enhanced heat transfer capability and contribution to higher overall system efficiency after integrated commercial PCM and T-fin absorber.

Numerical Analysis on the Aerodynamic Characteristics of SUV Car Model Install with Vortex Generator

Tue, 10 Dec 2024 00:00:00 +0700

The investigation of automotive aerodynamics involves analysing several forces operating on a car while driving on the road, such as drag and lift forces. The flow separation at the vehicle's rear end is one of the primary causes of aerodynamic drag for automobile vehicles. It is feasible to improve fuel efficiency by lowering the drag force. The study focuses on the influence of a vortex generator (VG) on the aerodynamics of a sport utility vehicle (SUV) car. The study aims to simulate fluid flow analysis for an SUV car that uses VG and without VG, as well as to assess the impact of a different configuration of VG and a varying number and fillet radius of VG. The number of VG are 3, 5, and 9. The different fillet radius of VG are 5, 10, and 15 mm. Using the Reynold-Averaged Navier Stokes Equation (RANS) in the numerical simulation, the Reynolds number at the computational domain is 1.1391 × 10⁷ and 1.4808 × 10⁷, which is determined by the height of the model and the freestream velocity. The results show that aerodynamic characteristics are significantly influenced by the number of VG and various size radius fillets of VG. From the result, 9 number of VG and 5 mm fillet radius obtained the lowest value of coefficient of drag, C_dcompared with the others which is C_d = 0.3747 for 27.78 m/s and C_d = 0.5031 for 33.33 m/s, respectively. Furthermore, the analysis of flow structures suggested the locations of vortex formation and wake turbulence at the rear of the vehicle. In contrast, the 9 number of VG with a 5 mm radius fillet of VG emerged as the most suitable VG for this scenario, exhibiting a C_d value closest to the base model and the lowest C_d value.

Simulation-Based Radiation Shielding and Optical Properties of Thulium-Doped Bismuth Tellurite Glass

Tue, 10 Dec 2024 00:00:00 +0700

Lead-based radiation shielding material is currently used in industry to shield against high-penetration radiation such as gamma rays. However, lead is harmful to humans, animals, and plants. This study proposed a new composition of transparent lead-free glass. Using the melt and quench technique, thulium-doped bismuth tellurite glass with composition (TeO₂)_1-x (Bi₂O₃)_x (Tm₂O₃)_0.02 where x = 0.05, 0.10, 0.15, and 0.20 mol % was fabricated. Significantly, the glasses with Bi₂O₃ concentration of 5 mol % and 10 mol% have a higher density than the commercial glass containing lead indicating the fabricated glasses would perform better as a radiation shielding material. Comparing the simulated-radiation shielding properties using software Phy-X and XCom, the glass with 10 mol% of Bi₂O₃ performs better as radiation shielding material than 5 mol% of Bi₂O₃. Meanwhile, glass with 5 mol% of Bi₂O₃performs better than 10 mol% of Bi₂O₃ in terms of optical properties. Considering both radiation shielding and optical properties, the fabricated lead-free glass can be widely used in radiation shielding applications that require transparency.

Comparative Analysis of Aerodynamic Drag between Long Tail and Short Tail Aero Helmets through Wind Tunnel Testing

Mohd Na'im Abdullah, Faizal Mustapha, Siti Zubaidah Mat Daud — Tue, 10 Dec 2024 00:00:00 +0700

Aerodynamic drag is a critical factor influencing the performance of competitive cyclists, particularly in time-trial events, where reducing drag can significantly improve speed and efficiency. Helmets are an essential component of aerodynamic gear, and their design plays a vital role in minimizing air resistance. However, the effect of different helmet shapes and head positions on aerodynamic performance has not been thoroughly examined. This study aims to investigate and compare the aerodynamic performance of long-tail (LT) and short-tail (ST) aero helmets, along with the Kabuto Aero SL, under varying pitch angles and speeds. Wind tunnel testing was conducted using an adult-sized mannequin head, with helmets evaluated at pitch angles ranging from 15° to 45° and wind speeds of 5 to 15 m/s. The results showed that the LT Aero helmet achieved the best performance at lower pitch angles (15°), while the ST Aero helmet performed optimally at a 25° pitch angle. The Kabuto Aero SL helmet demonstrated superior performance at low pitch positions, particularly at 15°. These findings highlight the importance of helmet design and head positioning in optimizing aerodynamic efficiency for cyclists in competitive conditions.

Assessment of the Effect of using a Magnetic Field on a Single Slope Solar Still Performance Integrated with an External Condenser Unit

Tue, 10 Dec 2024 00:00:00 +0700

As population density rises, the need for potable water grows. Solar distillation is the method of transforming briny water into drinkable water. We use solar desalination to desalinate untreated water. People commonly apply the desalination process to obtain pure water using solar stills. The primary classifications of solar stills are active and passive. This work aims to boost productivity by experimentally implementing the condensation and evaporation processes inside the still. To achieve this, we incorporate a magnetic field and an external condenser into the traditional distillation apparatus. The findings indicate that the outputs of the traditional solar still, the traditional solar still with a magnetic field and an external condenser (CSS-MACO), and the traditional solar still with a magnetic field (CSS-MAG) are 3.800, 5.210, and 5.800 L/m²/day, respectively. Therefore, the utilization of a magnetic field results in a 52.63% increase in productivity, while the combination of a magnetic field and an external condenser leads to a 37.10% improvement, compared to the typical solar still. From a cost analysis perspective, incorporating a magnetic field alongside a conventional solar still is the most cost-effective choice in terms of the total expense per liter of pure water. To be more specific, the cost is 0.016 USD, which is 30.43% lower than the CSS cost.

Hydrogen Production by Formic Acid Decomposition with Nanoscale Zero-Valent Iron (nZVI): Effects of nZVI Dosage, Temperature and Time

Tue, 10 Dec 2024 00:00:00 +0700

Amidst growing interest in renewable hydrogen gas production, this paper examines three important parameters affecting hydrogen production via formic acid decomposition reaction with nanoscale zero-valent iron (nZVI). The study investigates variations in nZVI dosage (200 – 1000 g/L), reaction temperature (25 – 75°C), and reaction time (5 -30 minutes) to identify optimum conditions for maximum hydrogen yield. Results indicate that the maximum hydrogen yield occurred at nZVI dosage, reaction temperature, and time of 800 g/L, 25°C and 30 minutes, respectively, yielding approximately 215 mL of hydrogen at optimal parameter values. The synthesized nZVI was also analysed before and after the reaction, focusing on the specific surface area and pore size of the nZVI. The results from BET characterization regarding specific surface area and pore size are consistent with experimental results, suggesting smaller pores correspond to higher surface area, enhancing reactivity with formic acid to produce hydrogen gas. Conversely, larger pore sizes after the reaction signify reduced surface area and lower reactivity of nZVI.

Hydrolysis Process of Red Sorghum Grains for Producing Bioethanol

Tue, 10 Dec 2024 00:00:00 +0700

As part of the effort to continuously enhance the development and utilization of bioenergy/bioethanol and to ensure its sustainability, using sorghum as a raw material for bioethanol production requires a study to obtain efficient hydrolysis conditions and achieve optimal bioethanol conversion. This research method is divided into two main parts: samples with pretreatment and without pretreatment. The pretreatments used NaOH solution (0.05% and 0.1%); soaking temperatures at 35,40 and 45^oC; and soaking time at 30, 60, 90, and 120 minutes. The liquefaction and saccharification results with pretreatment showed a greater decrease in viscosity values after both liquefaction and saccharification, and the RS and DE results also demonstrated an increasing trend compared to samples without pretreatment. It is due to the presence of protein bodies in sorghum that inhibited hydrolysis without applying the pretreatment. The best result on the reduced sugar (RS) value achieved was 10.43%, and the DE value was 67.90%. Thus, the optimum operational condition was achieved with a sample with 0.05% NaOH soaking for 90 minutes at 45°C (A9). Subsequently, fermentation was carried out on sample A9 with pretreatment and sample without pretreatment (A0/B0). The alcohol obtained from fermentation with pretreatment was 9.5%, with a fermentation ratio (FR) of 86.97%. Meanwhile, the alcohol yield from fermentation for the sample without pretreatment was 8.9%, with an FR of 83.02%.

Numerical Investigation of a Heat Exchanger with Annular Fins for Cryocooler Application

Tue, 10 Dec 2024 00:00:00 +0700

In this paper, the heat transfer characteristics of a typical hot heat exchanger used in pulse tube cryocooler have been numerically investigated. The numerical simulation is performed with the help of the commercial tool Ansys Fluent® to study the effect of different shapes and sizes of fins on the rate of heat transfer. The major parameters of the analysis include the diameter and pitch of the fins, the oscillating temperature at the inlet and outlet of the heat exchanger, and its operating frequency. A numerical investigation is conducted for the annular fin to illustrate its effect on the rate of heat transfer by calculating its Nusselt number and heat transfer coefficient. The effect of with fin and without fin on temperature and pressure variations has been studied for different angles in a cycle. The vortex development mechanisms within the gap between fins have been analyzed and compared with the vortex development mechanisms without fin. Results will be helpful for better design of heat exchangers for cryocoolers.

Review of Cooling Techniques for Improving Solar Photovoltaic Panel Efficiency

Tue, 10 Dec 2024 00:00:00 +0700

The increasing demand for renewable energy sources, particularly solar photovoltaic (PV) systems, aims to meet global energy needs while addressing environmental concerns. However, the efficiency of PV cells decreases drastically with increasing temperatures. This paper discusses different cooling methods to lessen the effects of temperature on the effectiveness of solar cells. It provides an overview of passive cooling strategies, including radiative cooling, natural convection, phase change materials, and reflective coatings, alongside active approaches such as water cooling, air cooling, and thermoelectric cooling. The integration of these techniques and their impact on solar panel efficiency are discussed, highlighting their potential to enhance performance. Furthermore, the paper discusses the challenges and limitations of existing cooling techniques and underlines future research directions utilizing newly developed materials and computationally advanced models. Policy considerations are also addressed to encourage the adoption of efficient cooling methods. This review aims to enhance solar PV systems' overall efficiency and reliability, moving a step towards a clean energy future.

Improving Li-ion Battery Performance with Internal Cooling

Tue, 10 Dec 2024 00:00:00 +0700

The use of Li-ion batteries has expanded fast in recent decades due to the rising use of electric vehicles, mobiles, laptop, robots’ drone, digital cameras etc., but there are numerous issues with batteries, including thermal runaway, cell rupture, decreased battery life, and an internal short circuit caused by overheating and overcharging. High-power draw systems tend to heat the battery beyond its safe operating temperature range, reducing the cell's lifespan. Researchers used a variety of battery heat management systems (internal/external) to tackle these issues. Most researchers, as well as commercial applications, have embraced external cooling systems employing air, PCM, or liquid cooling. There is a shortage of study on cell internal cooling. Internal cooling of Li-Ion prismatic cells and battery packs has been designed and analysed in this study (2S-2P). Under various C rates, we observed heat generation. Then we used rectangular flow channels inside the electrodes and de-ionized water as a coolant. CFD analysis were done for simulation. Without cooling, the maximum temperature of the battery pack was 338K, but after internal cooling, the maximum temperature of the battery pack was 306K, which is ideal for maintaining good battery health.