KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 12

Some of the metrics are blocked by your
consent settings
Predictive Three-Dimensional CFD Modeling of Evaporation-Coupled PVDF/DMF Spin-Coating on Finite Square Substrates
(2026-01-01)
Vichachai, Ratiwat
;
Thongsri, Jatuporn
;
Wasapinyokul, Kamol
Predictive thickness control remains challenging for spin-coated polymer films on finite, noncircular substrates, particularly with solvent evaporation. This study presents a three-dimensional computational fluid dynamics framework to simulate poly(vinylidene fluoride) dissolved in dimethylformamide during spin-coating on a finite square substrate. The model resolved free-surface hydrodynamics, interfacial solvent evaporation, species transport, and concentration-dependent viscosity to capture evaporation-coupled thinning dynamics. The simulation results were corrected with a dry-film equation based on mass conservation to obtain the film profiles. Two simulated cases—nonevaporating and evaporating—were investigated for three parameters—spin-coating time, rotational speed, and solution concentration. The nonevaporating model was validated against the one-dimensional analytical solution, while the evaporating model was validated against experimental values. Both the simulated and experimental thicknesses exhibited good quantitative agreement, confirming that the model accurately captured the film formation mechanisms. Remaining discrepancies were attributed to liquid retention at the substrate edge, uncertainty in initial dispensed volume, and numerical resolution effects near the interfacial regions. The model revealed that evaporation-induced viscosity evolution significantly modified thinning behavior, particularly at low speeds and high concentrations, and amplified edge accumulation on finite substrates. This work establishes a predictive framework for thickness and profile control in spin-coated polymer films.
Some of the metrics are blocked by your
consent settings
Effect of Detergent, Temperature, and Solution Flow Rate on Ultrasonic Cleaning: A Case Study in the Jewelry Manufacturing Process
(2025-12-01)
Juangjai, Natthakarn
;
Chaiaiad, Chatchapat
;
Thongsri, Jatuporn
This research investigated how detergent type and concentration, solution temperature, and flow rate affect ultrasonic cleaning efficiency in jewelry manufacturing. A silver bracelet without gemstones served as the test sample, and the study combined harmonic response analysis to assess acoustic pressure distribution with computational fluid dynamics to examine fluid flow patterns inside an ultrasonic cleaning machine. Cleaning tests were performed under real factory conditions to verify the simulations. Results showed that cleaning efficiency depends on the combined chemical and ultrasonic effects. Adding detergent lowered surface tension, encouraging cavitation bubble formation; higher temperatures (up to 60 °C) softened dirt, making removal easier; and moderate solution flow improved the cleaning, helping to carry dirt away from jewelry surfaces. Too much flow, however, decreased cavitation activity. The highest cleaning efficiency (93.890%) was achieved with 3% U-type detergent at 60 °C and a flow rate of 5 L/min, while pure water at room temperature (30 °C) without flow had the lowest efficiency (0.815%), confirmed by weighing and scanning electron microscope measurements. Interestingly, maximum ultrasonic power concentration did not always match the highest cleaning efficiency. The study supports sustainable practices by limiting detergent use to 3%, in line with Sustainable Development Goal (SDG) 9 (Industry, Innovation, and Infrastructure).
Some of the metrics are blocked by your
consent settings
Investigations of Air-Flow Configuration, Heat Transfer Behavior and Thermal Performance in Heat Exchangers with XVB-Type Turbulence Generators Under Turbulent Flow Conditions
(2025-01-01)
Boonloi, Amnart
;
Jedsadaratanachai, Withada
This study employs numerical modeling using the finite volume method to analyze airflow and thermal structures when vortex flow (VTF) generators are installed in heat exchanger square ducts (HX-SD). The VTF generator used in this study is the X-V baffle (XVB), which is designed to enhance heat transfer rates. The XVB is an evolution of the V-baffle, a type of VTF generator known for its efficiency in improving heat transfer. It features an X-shaped structure (considered in the cross-sectional (CS) plane, y-z plane) to further optimize the design. The present research investigates the effects of XVB thickness, represented by the thickness ratio (b) to the HX-SD height (H) or hydraulic diameter (Dh) (b/H), with B-R values ranging from 0.05 to 0.20. Additionally, three XVB configurations (Types A, B, and C) are examined, along with two airflow directions: AFD-VD (airflow direction – V-Downstream) and AFD-VU (airflow direction – V-Upstream). The investigation focuses on turbulent flow conditions, analyzing air velocity within a Reynolds number range of Re = 3,000 to 16,000. The results indicate that VTF is generated throughout the HX-SD due to the pressure difference caused by flow obstruction from the XVB in all cases examined. By enhancing air mixing and disrupting the thermal boundary layer (Th-BL), the induced VTF significantly increases the heat transfer rate. The maximum observed increase in heat transfer was 7.95 times higher than that of a smooth, empty duct.
Some of the metrics are blocked by your
consent settings
NUMERICAL INVESTIGATION ON DAMAGE SCENARIOS OF VANE TRAILING EDGE USING THERMO-FLUID-STRUCTURAL ANALYSIS
(2025-01-01)
Jeatrakul, Karn
;
Tanpradit, Ditthaphat
;
Prapamonthon, Prasert
;
Raja, Vijayanandh
;
Ke, Zhaoqing
Gas-turbine nozzle vanes are used to increase the velocity magnitude of hot gas exiting the combustor. Thus, the vanes must operate at high turbine inlet temperatures (TITs). Essentially, the higher the turbine inlet temperature, the greater the thermal efficiency and propulsive efficiency. Nonetheless, this situation can cause severe damage to the vane material because of the repeated high thermal loads. Using thermo-mechanical analysis, this paper presents damage scenarios of a nozzle vane's trailing edge (TE) and their impact on flow and heat phenomena, including mechanical behavior of the vane material. As the upstream process, computational fluid dynamics (CFD) simulation with conjugate heat transfer (CHT) is used to numerically investigate flow physics and heat transfer phenomena. Then, for the downstream calculations, a static structure model for a steady temperature analysis is used. The NASA-MARK II vane profile is used to define vane boundaries in the computational domain. Broken vane TE scenarios are presented in both the streamwise and spanwise directions, with a short, shallow cutback expanding into a long, deep one from 0.1 cm x 1 cm to 0.3 cm x 3 cm. The numerical results are mainly presented and discussed in terms of variations in surface and internal temperatures, as well as von Mises equivalent stress and strain. The damaged TE, according to the findings, has a significant impact on the thermo-mechanical variations of the vane material. This emphasizes the severity of a damaged vane TE if the turbine is still operating without maintenance.
Some of the metrics are blocked by your
consent settings
A Feasibility Study for the Hot-Air-Assisted Reflow Soldering Process Based on Computational Fluid Dynamics
(2024-10-01)
Kanjad, Natcha
;
Chanbandit, Chanapat
;
Thongsri, Jatuporn
In hard disk drive (HDD) manufacturing, a reflow soldering process (RSP) employs heat generated at the welding tip (WT) to bond tiny electrical components for assembling an HDD. Generally, the heat was generated by an electric current applied to the WT. This article reports a feasibility study of using hot air based on computational fluid dynamics (CFD), a choice to assist heat generation. First, the WT and hot air tube (HAT) prototypes were designed and created. The HAT is a device that helps to supply hot air directly to generate heat at the WT. Then, the experiment was established to measure the temperature (T) supplied by the hot air. The measure results were employed to validate the CFD results. Next, the prototype HAT was used to investigate the T generated at the WT by CFD. The comparison revealed that the T measured by the experiment was in the 106.2 °C–133.5 °C range and that the CFD was in the 107.3 °C–136.6 °C range. The maximum error of the CFD results is 2.3% compared to the experimental results, confirming the credibility of the CFD results and methodology. The CFD results revealed that the operating conditions, such as WT, HAT designs, hot air inlet velocity, and inlet temperature, influence the T. Last, examples of suitable operating conditions for using hot air were presented, which confirmed that hot air is a proper choice for a low-temperature RPS.
Some of the metrics are blocked by your
consent settings
CFD—Assisted Expert System for N2-Controlled Atmosphere Process of Rice Storage Silos
(2024-03-01)
Angsrisuraporn, Phakkawat
;
Samakkarn, Chawit
;
Lekawat, Lertsak
;
Singkhornart, Sasathorn
;
Thongsri, Jatuporn
Since organic rice storage silos were faced with an insect problem, an owner solved this problem using the expert system (ES) in the controlled atmosphere process (CAP) under the required standard, fumigating insects with an N<inf>2</inf>, reducing O<inf>2</inf> concentration to less than 2% for 21 days. This article presents the computational fluid dynamics (CFD) assisted ES successfully solved this problem. First, CFD was employed to determine the gas flow pattern, O<inf>2</inf> concentration, proper operating conditions, and a correction factor (K) of silos. As expected, CFD results were consistent with the experimental results and theory, assuring the CFD’s credibility. Significantly, CFD results revealed that the ES controlled N<inf>2</inf> distribution throughout the silos and effectively reduced O<inf>2</inf> concentration to meet the requirement. Next, the ES was developed based on the inference engine assisted by CFD results and the sweep-through purging principle, and it was implemented in the CAP. Last, the experiments evaluated CAP’s efficacy in controlling O<inf>2</inf> concentration and insect extermination in the actual silos. The experimental results and owner’s feedback confirmed the excellent efficacy of ES implementation; therefore, the CAP is effective and practical. The novel aspect of this research is a CFD methodology to create the inference engine and the ES.
Some of the metrics are blocked by your
consent settings
Effect of Nozzle Pressure and Shape Ratios on Gas Flow of a 122 mm Supersonic Rocket Nozzle investigated by CFD
(2023-01-01)
Chaiaiad, Chatchapat
;
Thongsri, Jatuporn
This article reports the effect of nozzle pressure ratio (NPR) and shape ratio (SR) on the gas flow of a 122 mm supersonic rocket, a convergent-divergent nozzle, using computational fluid dynamics (CFD). The NPR is the ratio between the pressure inlet and outlet, while the SR is the ratio between the outlet and throat areas of the nozzle. The CFD results revealed the gas flow, pressure (P), Mach number (M), temperature (T), shock, and jet for some conditions of NPR and SR, consistent with the theory. Furthermore, it was found that M increased with increasing NPR and/or SR. Furthermore, T enhanced with increasing NPR but decreased with increasing SR. This report can be used to further development of this nozzle type suitable for missions.
Some of the metrics are blocked by your
consent settings
Gas Flow and Ablation of 122 mm Supersonic Rocket Nozzle Investigated by Conjugate Heat Transfer Analysis
(2022-09-01)
Thongsri, Jatuporn
;
Srathonghuam, Kamonwan
;
Boonpan, Adulyasak
The propellant gas flow of a supersonic rocket in inappropriate operating conditions can cause excessive ablation inside a nozzle. In this research, conjugate heat transfer analysis (CHTA), consisting of computational fluid dynamics (CFD) and finite element analysis (FEA), was applied to investigate the gas flow and ablation of a 122 mm nozzle as a case study in the transient state, based on actual operating conditions. First, the nozzle was tested in a static experiment. Then, the experimental results were employed for CHTA settings and validation. Next, after completing the CFD calculation, the results revealed that the nozzle’s gas flow, temperature, pressure, Mach number, shock, etc. were consistent with theoretical results. Finally, using the CFD results as loads, the FEA results showed the equivalent von Mises stress (σ<inf>v</inf>), which was consistent with the ablation results from the experiment, as expected. The more the σ<inf>v</inf>, the greater the ablation. Both σ<inf>v</inf> and ablation were high near the throat and decreased further away. In addition, increasing the insulators’ thickness reduced σ<inf>v</inf>, leading to ablation reduction. The research findings contribute to an understanding of ablation and the methodology of employing CHTA to improve the design of 122 mm and other nozzles with reduced ablation for higher efficacy.
Some of the metrics are blocked by your
consent settings
Derosion Lattice Performance and Optimization in Solving an End Effect Assessed by CFD: A Case Study in Thailand’s Beach
(2022-05-01)
Thongsri, Jatuporn
;
Tangsopa, Worapol
;
Kaewbumrung, Mongkol
;
Phanak, Mongkol
;
Busayaporn, Wutthikrai
Thailand’s beach had a severe coastal erosion problem at the end of rock dams called the “end effect”. One of the innovative solutions to solve this problem is to use the derosion lattice (DL). However, since the DL performance depends on installing conditions such as angle of attack, placement position, terrain, and climate, computational fluid dynamics (CFD) was applied to assess the end effect’s occurrence and optimize the performance of DL’s installation. Based on Khao Rup Chang’s condition, a suffered beach in Thailand was used as a case study, and a free surface flow simulation was performed in the transient state using ANSYS Fluent, a CFD software, which revealed water waves flow through the beach with and without the DL installation cases. Furthermore, the CFD-assessed results indicated that the angle of attack and placement position affected the DL performance as expected. In optimization, the 15<sup>◦</sup> angle of attack with the DL placement adjacent to the rock dam was the proper condition. After being applied at the actual site, the DL can help reduce erosion, increase sedimentation, and solve the end effect with excellent performance.
Some of the metrics are blocked by your
consent settings
Performance Improvement of The Domestic Refrigerator Using Phase Change Materials
(2022-01-01)
Eakvanich, Visit
;
Wattana, Wassachol
;
Taweekun, Juntakan
A growing environmental Impact of global warming and rapidly increasing cost of the electrical energy cause researchers in the field of refrigeration and air conditioning to develop the sustainable cooling technologies. This study investigated the influence of latent heat storage materials on the power consumption and the temperature distribution of a commercial domestic refrigerator. The 2 kg PCMs (Phase change materials) slab of thickness 5 mm, which consisted of a 2:1 by weight mixture of refined paraffin wax and kerosene oil, were located on the back side of the roll-bond evaporator and the copper coated steel tubing coils of the hot-wall condenser, in order to improve the higher performance of refrigerator and to decrease the operating cycle time of the compressor. The experimental and CFD (Computation fluid dynamics) simulation results indicated that the refrigerator equipped with the PCMs storage unit showed a significant enhancement of the system performance and a reduction of the temperature fluctuations in the refrigerator compartment compared to a conventional system. In this investigation, the electric power consumption and the compressor on-time ratio were reduced by 15.69% and 12.13%, respectively. Moreover, the COP (Coefficient of performance) of the refrigeration system was increased by 9.53%.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results