Journal of Research and Applications in Mechanical Engineering

Performance Assessment of Solar Air Heater Channel with Inclined Groove Turbulators

2024-09-16T21:19:00+07:00

An experimental investigation was carried out to explore the thermal performance and frictional loss features in a solar air heater (SAH) channel that was intentionally roughened on the absorber surface using multiple inclined groove turbulators. The working fluid, air, flows into the SAH channel, which has a consistent surface heat flux for Reynolds numbers (Re) varying between 5290 and 22,600 in the current research. Thermal characteristics at a single inclination angle (a = 45°) are investigated in this research by comparing the effects of three distinct relative groove frequencies (P/H=PR=0.8, 1.2 and 1.6) and groove depth ratios (D/H=DR=0.16, 0.24 and 0.32). The findings highlight that the employ of inclined grooves results in a noticeable rise in Nusselt number (Nu) from 1.24 to 2.82 times relative to the smooth absorber plate (smooth channel), as well as a 1.88 to 7.9 times increase in friction factor (f). The Nu and f show an increasing trend when Re increases, whereas the opposite pattern occurs as DR and PR increase. At PR = 0.8 and DR = 0.32, the inclined groove roughness has the largest thermal effectiveness factor (TEF) of around 1.64. The Nu and f correlations, which are functions of inclined groove features, have also been established.

Combustion Characteristics of Liquefied Petroleum Gas with Ammonia addition on Slot Burner

2024-09-12T20:00:31+07:00

This research focused on Liquefied Petroleum Gas combustion with ammonia (NH₃) non-premixed flame on a slot burner which combustion characteristics were investigated for decrease of carbon dioxide (CO₂). LPG combustion with flow variation of NH₃, (LPG: NH₃) was experimentally applied on slot burner to study flame shape, OH intensity, flame temperature, emission of NO_x, CO and exhaust gas temperature. As the results, the flame color became blue-yellow due to NH₂ radical from NH₃ added in LPG combustion. Moreover, NH₃ addition in LPG affected the combustion characteristics such as burning velocity, flame appearance, flame stability, flame temperature, NO_x and CO emissions. This research was clarified that NH₃ could be applied with LPG combustion and the lower burning velocity, blow off flame, unstable flame, lower flame temperature, higher NO_x, lower CO and CO₂ were achieved at less 60% of NH₃ addition.

Numerical Simulation of Harmonic Gust Induced 2D Low-Re Incompressible Flow Over Tandem Circular Cylinders using ECFRUNS

2024-09-05T21:57:46+07:00

The paper presents a numerical investigation of the harmonic gust induced two dimensional incompressible flow over two tandem circular cylinders configurations. The extended cell flux reconstruction scheme (ECFRUNS), developed for unstructured triangular cells grid, have been employed for the flow solution. The gust angular frequency (ω), which is the variable generating impulse harmonic gust and affecting inlet flow fluctuations, has been investigated to identify its effective value for improved qualitative wake characteristics. The low- Reynolds number (Re) as a second flow variable has been investigated with an impulse harmonic (gusty) inflow to examine the effect of the Reynolds number under gusty situations. The non-dimensional longitudinal gap-to-diameter ratio (R = L/D) as a geometrical variable has also been investigated to check its effect with a combination of flow variables and gust. The streamlines and vorticity contours are employed for quantitative flow visualization. The force coefficients (C_l & Cd), and the Strouhal Number (St) have been computed as quantitative result parameter. They are compared with literature wherever possible. The investigated flow characteristics i.e. vortex shedding frequency, gap flow, wake region have been discussed in detail. The investigations establishes the capabilities of ECFRUNS scheme to solve one dimensional harmonic gust induced low-Re incompressible external flow problems explicitly directly on physical plane.

Soft Pneumatic Actuator Designed After Human Finger Motion

2024-09-16T22:05:26+07:00

Soft pneumatic actuators (SPAs) are characterized by their soft, flexible, and compliant nature. Typically made from elastomeric materials, SPAs are controlled through the inflation and deflation of pneumatic chambers or channels. Their adaptability and compliance make them suitable for various applications, including deep-water exploration, wearable devices, soft robotics, and human-machine interaction. In this study, a soft pneumatic finger actuator inspired by the human finger was designed. The Ogden hyperelastic material model was used to simulate the bending behavior of the actuator. The analysis revealed that the SPA exhibited noticeable bending or deformation (19.58 mm) with higher pneumatic pressure (10 kPa). To further improve deformation or bending behavior, an air gap was introduced between adjacent chambers. This modification resulted in increased deformation (55.3 mm) of the SPA, even at lower pressures (5 kPa) compared to the original design. In the future, this design could be used for the development of soft wearable hand glove for rehabilitation exercises.

Predicting Performance and Emission Characteristics of Compression Ignition Engine Using Artificial Neural Network with Biodiesel Blends from Used Temple Oil

2024-10-25T21:09:12+07:00

Power generation is highly dependent on compression ignition engines, which are mostly compression ignition engines with no power output that release dangerous toxic gases such as petrol and diesel, contaminating the atmosphere by disturbing local ecosystems and contributing to environmental problems. Efforts to solve this problem have focused on alternative fuels, and oil-based biodiesels are a popular choice owing to their sustainability and diesel-like performance. Towards this objective, the present study is focused on development of artificial neural network models for the performance and emission characteristics of biodiesel to reduce the physical testing which demand high resource inputs by making property based predictions more accurate. The brake specific fuel consumption (6–5–1), brake thermal efficiency (6-3-1) and exhaust gas temperature (6-5-1) are the best ANN model architectures for forecasting different performance metrics. The model obtained MSE of 0.0397, RMSE of 0.1993, MAD of 0.1234 and MAPE of 0.5599 for brake thermal efficiency prediction. According to the sensitivity analysis, the model for brake thermal efficiency and exhaust gas temperature is sensitive to fuel consumption. The ANN model for brake specific fuel consumption is significantly sensitive to torque, and the model for brake specific energy consumption is sensitive to breaking power, which provides credence to the wider use of a biodiesel as a practical substitute of fuel, especially for products made from used temple oil. This change may contribute to a greener future by lowering a greenhouse gas emission and promotes better energy practices.

Nonlinear Vibration Analysis of Phased-controlled Actuator Capable of Movement inside Iron Structures

2024-10-12T15:46:53+07:00

In recent years, an iron structures that form the framework of buildings, bridges, and other structures have become enormous. As a result, workers are performing hazardous work such as welding and cutting at high altitudes. Due to a falling birth rate and aging population, Japan has a shortage of workers in various fields. Automation using robots is thus promoted at in various fields. In this study, a phase-controlled actuator is proposed as a power source for robots. A two-degree-of-freedom nonlinear vibration model of the actuator is theoretically analyzed. A static analysis of the actuator movement is also carried out. It is found that the movement characteristics of the actuator can be predicted based on the theoretical analysis results. Furthermore, it is verified that the results of the theoretical analysis well agree with the measurement results obtained in device tests. A single phase-controlled actuator can play the role of several motors. Furthermore, if this phase-controlled actuator is equipped with a micro camera, visual inspection of iron structures can be performed.

Enhancing Combustion Analysis: Implementation and Validation of Laminar Premixed Methane-Air Jet-Impinging Flame Simulation in OpenFOAM

2024-10-20T11:14:29+07:00

This research utilized the open-source toolbox OpenFOAM to conduct a numerical investigation of the laminar premixed methane-air jet-impinging flame. OpenFOAM, a software based on computational fluid dynamics (CFD) and employing the finite volume method (FVM), was used to perform transient simulations with a chemically compressible reacting flow model integrated with a conjugated heat transfer model. Key parameters such as burner-to-plate distances (H/d = 0.04 and 0.06 m), mixture equivalence ratios (ɸ = 0.8-2.0), and Reynolds numbers (Re = 500, 750 and 1,000) were varied to thoroughly examine their effects. The simulated results were rigorously validated against experimental data from previous research, focusing on flame height and thermal efficiency, which are critical parameters in the jet-flame impinging system. The validation demonstrated a strong correlation, confirming the accuracy and reliability of the simulations. This alignment underscores the usefulness of the modeling approach and highlights the potential of using OpenFOAM for detailed combustion studies, paving the way for future research and optimization in this field.

Numerical Study of Anthracite Blended with Petroleum Coke on Swirl-JET Burner in Cement Kiln

2024-10-27T13:15:05+07:00

This research focuses on studying and improving the combustion of anthracite coal blended with Petroleum coke in a ratio of 89:11 by mass. The numerical study was conducted using Ansys Fluent. In cement kiln operations, the Swirl-JET burner has been observed to cause melting of cement at the burner outlet, leading to clogging after a few months of operation. To validate the numerical model with real operating conditions of the cement kiln burner, the study analysed char particle combustion, combustion characteristics, kiln surface temperature, air velocity distributions, and temperature distribution. Additionally, the research examined the effect of varying the swirl angle of the swirl air outlet (40°, 25° and 14°). The results showed that decreasing the swirl angle reduced coal scattering at the burner outlet and shifted combustion further from the burner outlet. Furthermore, blending Anthracite coal with Petroleum coke in a ratio of 89:11 by mass, due to the smaller particle size and higher lower heating value, improved combustion characteristics. This blend prevented recirculation flow near the burner outlet and enhanced flame temperature along the cement kiln. In conclusion, decreasing the swirl angle and blending Anthracite coal with Petroleum coke are effective strategies to reduce burner clogging and improve flame temperature in cement kiln operations.

Development of the Cooling Load Calculation Program Using MATLAB as a Stand-Alone Application

2024-11-17T22:31:28+07:00

A stand-alone MATLAB application was developed for cooling load calculations and cooling system design. The program enables quick and accurate calculations without requiring a MATLAB license, reducing costs and improving accessibility. It significantly expedites the cooling load calculation and system design process, cutting time by 50%. The application serves as an educational tool and supports research in efficient cooling technologies, particularly radiant cooling systems. By facilitating better-designed cooling systems, the program contributes to energy conservation and the reduction of greenhouse gas emissions.

Computational Fluid Dynamics Analysis for Heat Transfer Enhancement in Single Horizontal Pipe Heat Exchanger Full Filled Using Different Types of Porous Material

2024-11-17T21:36:13+07:00

As a result of significant scaling challenges and complex engineering, there has been considerable academic interest in recent years in the use of porous materials to improve forced convection heat transfer. The current work involves computational fluid dynamics (CFD) numerical simulation using three types of porous material (glass, steel and ceramics) with different diameters (0.004, 0.006 and 0.005 m), respectively to optimize heat transfer for a concentric single-tube heat exchanger with a length (1 m) and a diameter (0.03 m) exposed uniform heat flux on the outer wall (60kW/m²). The governing equations of steady single-phase turbulent flow were solved using the commercial program (Ansys Fluent) for the Reynolds number range (10000-19000). Under the same operating conditions, the four cases of the heat exchanger tests were carried out, namely the three cases of the porous medium plus the exchanger without the porous medium. The numerical results showed the heat transfer rate (Nusselt number) improved by (92.563%) when using the porous material ceramic type compared to the empty pipe, while using the porous material (glass and steel) percentage increased (91.44 and 87.86%), respectively. Moreover, the friction factor may be affected by the inclusion of the porous material, and by increasing the Reynolds number gradually decreases. The current study proposes the inclusion of nanomaterials as a composite technology with porous material to improve the heat transfer properties and the flow of various fluids through the heat pipe.

Exploring Mechanical Properties of Additive Manufactured Patient-Specific Finger Splints through FEA and Experimental Testing

2024-11-04T21:23:08+07:00

The primary objective of the study is to assess the mechanical suitability of each filament material for finger splint applications and to determine their behaviour under compressive loads. Several filament materials were used in the design and Additive Manufacturing of patient-specific finger splints. Finite Element Analysis simulations were then used to forecast mechanical responses. The simulation results are then verified and the mechanical characteristics of the splints are measured through experimental compression testing. The study's main conclusions highlight the unique mechanical properties of each filament material, such as differences in stiffness, strength, and resilience. Nylon splints showed good flexibility and toughness, while PLA and ABS splints showed differences in flexibility and moderate strength. PC splints are ideal for applications needing strong support because of their high strength and rigidity. The study has implications for the choice of filament materials for patient-specific finger splints, taking into accounts the desired mechanical properties and clinical needs. By offering useful data for improving the design and manufacture of customized finger splints, these findings advance orthopedic care.

Numerical Investigation of the Greenhouse with the Floor and Other Cooling Systems

2024-11-05T20:18:04+07:00

This study used computational fluid dynamics (CFD) simulations to explore the effect of the greenhouse with the floor and other cooling systems (only an evaporative cooling system, only a floor cooling system, and equipped with both cooling systems) on temperature distributions inside a greenhouse. Three scenarios were analyzed using the finite volume method and several the Realizable k-ε turbulence model offered superior accuracy compared to the Standard k-ε model in simulating temperature distributions. However, significant discrepancies were observed near the wall surfaces of the greenhouse. To address this, a radiation model was incorporated alongside the Realizable k-ε turbulence model, which improved simulation accuracy by reducing error percentages down to 2-3% and better matching experimental results. The study emphasizes the importance of using the Realizable k-ε turbulence model with the radiation model to improve the accuracy of CFD simulations for the greenhouse with the floor and other cooling systems.

Influence of Delta Winglets on Improving heat transfer and friction factor characteristics in tubular heat exchanger

2024-11-01T22:31:16+07:00

Heat transfer rate and pressure drop characteristics are two critical constraints that substantially influence the advancement of solar air heaters. The thermal efficacy of these systems is significantly improved by factors such as flow configurations, thermal mechanisms, and geometric modifications. The integration of insertion in turbulators is a common method to improve heat transfer efficiency in solar air heaters. This article presents heat transfer and thermal efficiency in a tubular heat exchanger incorporating Delta winglet (DW). The thermal transfer and pressure drop of air as a working fluid in a tube with a constant heat flux were quantified for Reynolds numbers (Re) between 6000 and 20,000. The DW elements were positioned on two tape sides in a configuration with attack angles (θ) of 30°, 45°, and 60°. Delta winglet height ratios (h/D=0.10) and pitch ratios (p/D=0.1) were examined. Data from the current smooth or plain tubes were also analyzed for comparative purposes. According to the experimental results, the tube with this inserted has a much higher Nusselt number (Nu) and friction factor (f) than a plain tube. Both Nu and f increase as θ decrease. The DW enhances Nu and f by approximately 2.51-3.04 times and 5.21-7.16 times, respectively. The maximum TEF of 1.34 is achieved at an attack angle of 30° and a Reynolds number of 6000. The statistical correlations for Nu f and TEF were analysed and demonstrated a strong fit to the observed data, with discrepancies of ±4%, ±5% and ±3%, respectively. This design improves the conservation of energy in heat exchanger tube applications.

Leveraging Generative Artificial Intelligence for Prototyping: Ambidextrous Thinking in Engineering Design

2024-10-12T15:41:18+07:00

Rapid economic and technological changes make the future increasingly unpredictable in the current society. Consequently, an urgent need exists to cultivate human resources capable of making significant contributions, particularly in education, where design education programs play a crucial role. In engineering design, “ambidextrous thinking” has also garnered significant attention. This study has two main objectives: (1) To develop a new evaluation method and provide guidelines for future studies by performing large language model (LLM)-based evaluations of prototyping, specifically along the axes of exploration and exploitation. (2) To quantitatively and qualitatively analyze the impact of design education on engineering. This study evaluates 31 product redesigns by third-year students enrolled in the Design Engineering course at Kogakuin University. In the LLM-based evaluation of “exploitation,” 70% of the top 10 proposals suggested by ChatGPT received the highest rating from the class instructor. In addition, in the “exploration” evaluation, incorporating the concept of “darkness” into the existing definition revealed the potential for a more effective evaluation of prototypes.

Impact of Battery Pack Shell Materials on Electrical Leakage in Submersion

2024-10-10T20:35:32+07:00

This study investigates the impact of battery pack shell materials on electrical leakage when fully submerged in seawater. Both conductive and insulating materials are utilized for battery pack shells. Simulations are conducted using the Finite Element Method (FEM) and are compared with experimental procedure to validate accuracy and reliability. After validation, the simulations are applied to different accident scenarios to analyze potential outcomes. The results revealed that the choice of materials significantly influences electrical leakage, as evidenced by simulations of various scenarios. Moreover, the voltage distribution changed with different battery pack shell states, indicating that the condition of the battery shell significantly impacts electrical leakage. Additionally, solutions for mitigating leakage were implemented and analyzed. Adding highly conductive materials between leaked positions can also reduce the current density in the surrounding areas. These findings are expected to provide valuable data for designing battery pack shells and enhancing the safety of electric vehicles (EVs) in potential accident scenarios.