Pub Date : 2024-05-17DOI: 10.37934/arfmts.117.1.155163
Muhammad Bukhari Rosly, Pramila Tamunaidu, Nurhamieza Md Huzir, Azlan Nur Rasyid Amin, Masafumi Goto, Abd Halim Md Ali, Mohd Danial Muhd Ali
The palm oil industry plays a vital role in Malaysia, but it generates substantial amounts of biomass waste, which, if not properly managed, can lead to environmental pollution. Among these waste products, oil palm empty fruit bunch (OPEFB) is the most abundant and underutilized, being generated daily without any commercial value. The aim is to efficiently convert OPEFB into fermentable sugars for improved biogas production. Nevertheless, the challenge lies in efficiently degrading OPEFB within a short timeframe before fermentation into biogas can occur. This study aims to explore the potential of hydrothermal pre-treatment as a means to enhance biogas production from OPEFB. The pre-treatment process was optimized by varying reaction temperatures (100 to 250°C), and reaction times (10 to 40 minutes). The main objective was to maximize the total soluble sugar yield, a crucial precursor for efficient biogas production. The optimal conditions for hydrothermal pre-treatment are identified at a temperature of 175°C and a reaction time of 20 minutes, resulting in a yield of 49.2 mg of glucose per gram of OPEFB. Subsequent anaerobic co-digestion of the treated OPEFB with digested sludge increased methane yield to 100.53 ml/g-VS, representing a remarkable 392% increase compared to the low 20.44 ml/g-VS produced by untreated OPEFB. Nonetheless, elevated pre-treatment temperatures (200°C and above) led to reduced biogas production due to inhibitory compounds. This study demonstrates the effectiveness of hydrothermal pre-treatment as a low-temperature, green technology for enhancing OPEFB-based biogas production, contributing to Malaysia's renewable energy goals. Future research should focus on scale-up and validation of this integrated process.
{"title":"Potential of Biogas Production from Anaerobic Co-digestion of Hydrothermal Pre-treated OPEFB and Digested Sludge","authors":"Muhammad Bukhari Rosly, Pramila Tamunaidu, Nurhamieza Md Huzir, Azlan Nur Rasyid Amin, Masafumi Goto, Abd Halim Md Ali, Mohd Danial Muhd Ali","doi":"10.37934/arfmts.117.1.155163","DOIUrl":"https://doi.org/10.37934/arfmts.117.1.155163","url":null,"abstract":"The palm oil industry plays a vital role in Malaysia, but it generates substantial amounts of biomass waste, which, if not properly managed, can lead to environmental pollution. Among these waste products, oil palm empty fruit bunch (OPEFB) is the most abundant and underutilized, being generated daily without any commercial value. The aim is to efficiently convert OPEFB into fermentable sugars for improved biogas production. Nevertheless, the challenge lies in efficiently degrading OPEFB within a short timeframe before fermentation into biogas can occur. This study aims to explore the potential of hydrothermal pre-treatment as a means to enhance biogas production from OPEFB. The pre-treatment process was optimized by varying reaction temperatures (100 to 250°C), and reaction times (10 to 40 minutes). The main objective was to maximize the total soluble sugar yield, a crucial precursor for efficient biogas production. The optimal conditions for hydrothermal pre-treatment are identified at a temperature of 175°C and a reaction time of 20 minutes, resulting in a yield of 49.2 mg of glucose per gram of OPEFB. Subsequent anaerobic co-digestion of the treated OPEFB with digested sludge increased methane yield to 100.53 ml/g-VS, representing a remarkable 392% increase compared to the low 20.44 ml/g-VS produced by untreated OPEFB. Nonetheless, elevated pre-treatment temperatures (200°C and above) led to reduced biogas production due to inhibitory compounds. This study demonstrates the effectiveness of hydrothermal pre-treatment as a low-temperature, green technology for enhancing OPEFB-based biogas production, contributing to Malaysia's renewable energy goals. Future research should focus on scale-up and validation of this integrated process.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"112 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141126730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.7587
Ahmad Ilham Ramadhani
Conventional gasoline engine fishing boats have several disadvantages, such as high exhaust emissions, high fuel consumption, and low service life. The disadvantages of the gasoline engine can be resolved by using the electrical engine. Electrical fishing boats is an improvement on conventional boat to reduce the fuel consumption and emissions. In realizing an electric fishing boat, a feasibility analysis of the design, shape and weight that can be accommodated is required. The feasibility of an electric fishing boat has been successfully carried out by simulating the boat on Maxsurf Software. The aim of this research is to analyze feasibility of conventional boats by designing electric fishing boats. Improving feasibility is carried out by calculating hydrostatic forces and resistance. Electric fishing boats design using the simulation model in Maxsurf Modeller and simulation of resistance in Maxsurf Resistance at speeds of 1, 3 and 5 knots, with Wyman method. The modeling results show that the electric fishing boat design has a pointed front configuration with a V-shaped bottom. Main dimensions LoA 3.49 m, width 0.8 m; height 0.5 m; and a draft of 0.2 m, the boat produces a hydrostatic force which includes a displacement of 301.5 kg, a midship draft and submerged area of 0.2 m, a wet area of 3.08 m2, and a waterline of 0.5 – 1.5 m. Testing 1, 3, and 5 knots, the boat experienced resistance of 26.11 N, 234.96 N, and 652.73 N respectively. The power required for the boat to operate was 13,43 W, 362.66 W, and 1678,97 W. The feasibility of designing an electric fishing boat is the main key to developing an electric fishing boat.
{"title":"Feasibility of Electric Fishing Boats based on Evaluation of Hydrostatic Forces and Resistance","authors":"Ahmad Ilham Ramadhani","doi":"10.37934/arfmts.116.2.7587","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.7587","url":null,"abstract":"Conventional gasoline engine fishing boats have several disadvantages, such as high exhaust emissions, high fuel consumption, and low service life. The disadvantages of the gasoline engine can be resolved by using the electrical engine. Electrical fishing boats is an improvement on conventional boat to reduce the fuel consumption and emissions. In realizing an electric fishing boat, a feasibility analysis of the design, shape and weight that can be accommodated is required. The feasibility of an electric fishing boat has been successfully carried out by simulating the boat on Maxsurf Software. The aim of this research is to analyze feasibility of conventional boats by designing electric fishing boats. Improving feasibility is carried out by calculating hydrostatic forces and resistance. Electric fishing boats design using the simulation model in Maxsurf Modeller and simulation of resistance in Maxsurf Resistance at speeds of 1, 3 and 5 knots, with Wyman method. The modeling results show that the electric fishing boat design has a pointed front configuration with a V-shaped bottom. Main dimensions LoA 3.49 m, width 0.8 m; height 0.5 m; and a draft of 0.2 m, the boat produces a hydrostatic force which includes a displacement of 301.5 kg, a midship draft and submerged area of 0.2 m, a wet area of 3.08 m2, and a waterline of 0.5 – 1.5 m. Testing 1, 3, and 5 knots, the boat experienced resistance of 26.11 N, 234.96 N, and 652.73 N respectively. The power required for the boat to operate was 13,43 W, 362.66 W, and 1678,97 W. The feasibility of designing an electric fishing boat is the main key to developing an electric fishing boat.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"129 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.5974
Noorina Abdul Rahman, Najiyah Safwa Khashi’ie, Iskandar Waini, Khairum Hamzah, Mohd Afzanizam Mohd Rosli, Ioan Pop
This work highlights the thermal progress and flow characteristics of the various hybrid nanofluids (graphene-alumina/water and copper-alumina/water) flow over a stretching/shrinking sheet with heat generation and suction effects using numerical approach. This study is important in identifying the nanofluids and physical parameters which beneficial in the increment of the flow and thermal progresses. The control model (partial differential equations) is established based on the boundary layer assumptions and then transformed into a set of ordinary (similar) differential equations. A numerical solver in the MATLAB software called the bvp4c solver is used to compute the solutions by first transforming the reduced ODEs. There is an increase in velocity profile and a decrease in thermal rate with the increased suction parameter. It is observed that between the two hybrid nanofluids, the Cu-Al2O3/H2O hybrid nanofluid has a larger thermal rate and skin friction coefficient compared to the Graphene-Al2O3/H2O, which makes Cu-Al2O3/H2O a good option for the industrial cooling processes.
{"title":"Unsteady Flow of Hybrid Nanofluids Subjected to a Stretching/Shrinking Sheet with Heat Generation","authors":"Noorina Abdul Rahman, Najiyah Safwa Khashi’ie, Iskandar Waini, Khairum Hamzah, Mohd Afzanizam Mohd Rosli, Ioan Pop","doi":"10.37934/arfmts.116.2.5974","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.5974","url":null,"abstract":"This work highlights the thermal progress and flow characteristics of the various hybrid nanofluids (graphene-alumina/water and copper-alumina/water) flow over a stretching/shrinking sheet with heat generation and suction effects using numerical approach. This study is important in identifying the nanofluids and physical parameters which beneficial in the increment of the flow and thermal progresses. The control model (partial differential equations) is established based on the boundary layer assumptions and then transformed into a set of ordinary (similar) differential equations. A numerical solver in the MATLAB software called the bvp4c solver is used to compute the solutions by first transforming the reduced ODEs. There is an increase in velocity profile and a decrease in thermal rate with the increased suction parameter. It is observed that between the two hybrid nanofluids, the Cu-Al2O3/H2O hybrid nanofluid has a larger thermal rate and skin friction coefficient compared to the Graphene-Al2O3/H2O, which makes Cu-Al2O3/H2O a good option for the industrial cooling processes.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"209 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.5158
Shital Yashwant Waware, Sandeep Sadashiv, A. Kurhade, Suhas Prakashrao Patil
This paper investigates heat transfer in a horizontally oriented tubular heat exchanger through a comprehensive examination of both numerical simulations and experimental analyses. The primary focus is on copper as the material of interest, specifically examining an inner tube with a 14 mm internal diameter and 1 mm thickness, as well as an outer tube with a 29 mm external diameter and 1 mm thickness. In addition to these components, two perforated pipes with internal diameters of 11 mm and 20 mm are incorporated; contributing to an overall length of the heat exchanger measuring 281 mm. Notably, the perforation pipe features a 5 mm diameter hole on its periphery. A comprehensive assessment was conducted to appraise heat transfer and coefficients within a straightforward tubular heat exchanger. The mass flow rate of chilled water in the annular space fluctuated between 0.01 kg/sec and 0.11 kg/sec, while the steady flow rate of hot water within the inner tube remained constant at 0.11 kg/sec. Inlet temperatures for the hot water were established at 55 °C, 75 °C, and 85 °C, with the cold water maintaining a consistent inlet temperature of 29 °C throughout the experiment.
{"title":"Innovative Heat Transfer Enhancement in Tubular Heat Exchanger: An Experimental Investigation with Minijet Impingement","authors":"Shital Yashwant Waware, Sandeep Sadashiv, A. Kurhade, Suhas Prakashrao Patil","doi":"10.37934/arfmts.116.2.5158","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.5158","url":null,"abstract":"This paper investigates heat transfer in a horizontally oriented tubular heat exchanger through a comprehensive examination of both numerical simulations and experimental analyses. The primary focus is on copper as the material of interest, specifically examining an inner tube with a 14 mm internal diameter and 1 mm thickness, as well as an outer tube with a 29 mm external diameter and 1 mm thickness. In addition to these components, two perforated pipes with internal diameters of 11 mm and 20 mm are incorporated; contributing to an overall length of the heat exchanger measuring 281 mm. Notably, the perforation pipe features a 5 mm diameter hole on its periphery. A comprehensive assessment was conducted to appraise heat transfer and coefficients within a straightforward tubular heat exchanger. The mass flow rate of chilled water in the annular space fluctuated between 0.01 kg/sec and 0.11 kg/sec, while the steady flow rate of hot water within the inner tube remained constant at 0.11 kg/sec. Inlet temperatures for the hot water were established at 55 °C, 75 °C, and 85 °C, with the cold water maintaining a consistent inlet temperature of 29 °C throughout the experiment.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"8 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141014520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.1326
Abel Alfeuz, Fadzlita Tamiri, Farm Yan Yan, Wan Khairul Muzammil, Melvin Gan Jet Hong, Dayang Salyani Abang Mahmod, Nuramalina Bohari, Mohd Azlan Ismail
The micro hydro system is the most favorable renewable energy source to supply electricity for rural areas. The Gravitational Water Vortex Power Plant (GWVPP) is one of the micro hydro systems that is suitable for very low-head hydropower sites. GWVPP consists of three major parts: electromechanical components, civil structures, and electric distribution. The micro hydro turbine in GWVPP is called a vortex hydro turbine and is used to convert induced vortex flow to mechanical energy coupled with a generator to produce electricity. This paper investigates crossflow vortex turbine performance using Computational Fluid Dynamics (CFD) software and experimental work. The CFD results provide qualitative and quantitative comprising velocity distribution, water vortex profile, and water vortex height. The optimum hydraulic performance in the water vortex was observed and determined for different turbine positions. The vortex crossflow turbine was placed 0.05 m from the bottom surface of the basin at the highest vortex tangential velocity. A 0.05 m turbine position was chosen for the turbine installations as it creates a high-velocity profile. The comparative performance was conducted on the vortex crossflow blade with different inlet blade angle designs at a range of 400 – 700. The experimental analysis was conducted at rotational speeds of 30 rpm – 70 rpm to determine its efficiency performance. The optimum design for the crossflow blade was at 500 with an operational speed of 50 rpm, which exhibited torque and power output at 0.27±0.02 m and 1.49±0.08 m respectively with an efficiency recorded at 18.98%.
{"title":"Performance Analysis of a Crossflow Vortex Turbine for a Gravitational Water Vortex Power Plant","authors":"Abel Alfeuz, Fadzlita Tamiri, Farm Yan Yan, Wan Khairul Muzammil, Melvin Gan Jet Hong, Dayang Salyani Abang Mahmod, Nuramalina Bohari, Mohd Azlan Ismail","doi":"10.37934/arfmts.116.2.1326","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.1326","url":null,"abstract":"The micro hydro system is the most favorable renewable energy source to supply electricity for rural areas. The Gravitational Water Vortex Power Plant (GWVPP) is one of the micro hydro systems that is suitable for very low-head hydropower sites. GWVPP consists of three major parts: electromechanical components, civil structures, and electric distribution. The micro hydro turbine in GWVPP is called a vortex hydro turbine and is used to convert induced vortex flow to mechanical energy coupled with a generator to produce electricity. This paper investigates crossflow vortex turbine performance using Computational Fluid Dynamics (CFD) software and experimental work. The CFD results provide qualitative and quantitative comprising velocity distribution, water vortex profile, and water vortex height. The optimum hydraulic performance in the water vortex was observed and determined for different turbine positions. The vortex crossflow turbine was placed 0.05 m from the bottom surface of the basin at the highest vortex tangential velocity. A 0.05 m turbine position was chosen for the turbine installations as it creates a high-velocity profile. The comparative performance was conducted on the vortex crossflow blade with different inlet blade angle designs at a range of 400 – 700. The experimental analysis was conducted at rotational speeds of 30 rpm – 70 rpm to determine its efficiency performance. The optimum design for the crossflow blade was at 500 with an operational speed of 50 rpm, which exhibited torque and power output at 0.27±0.02 m and 1.49±0.08 m respectively with an efficiency recorded at 18.98%.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"212 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.131143
Wadhah Hussein Abdulrazzaq Al Doori, Ali Mohammed Hussien
The Hydro-PowerStation is one of the keys (important) sources of electricity, and it has a digital governor, which improves production efficiency over mechanical governors. This research looked at the hydraulic turbine, found flaws such as oil leakage from the pumps utilized, calculated the amount of energy consumed, and worked to reduce it by measuring the losses and monitoring the poor process during periods of high water load of up to 83%. As a consequence of the research, it was discovered that the amount of energy consumed had decreased by 20%, by employing well-made, effective pumps for each unit according to its use, oil leakage in all units is reduced.
{"title":"Safe Energy using Hydraulic System Analysis at a Hydropower Plant","authors":"Wadhah Hussein Abdulrazzaq Al Doori, Ali Mohammed Hussien","doi":"10.37934/arfmts.116.2.131143","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.131143","url":null,"abstract":"The Hydro-PowerStation is one of the keys (important) sources of electricity, and it has a digital governor, which improves production efficiency over mechanical governors. This research looked at the hydraulic turbine, found flaws such as oil leakage from the pumps utilized, calculated the amount of energy consumed, and worked to reduce it by measuring the losses and monitoring the poor process during periods of high water load of up to 83%. As a consequence of the research, it was discovered that the amount of energy consumed had decreased by 20%, by employing well-made, effective pumps for each unit according to its use, oil leakage in all units is reduced.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"56 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Micropower generator is a micro-scale energy source that has two main components, namely a micro/mesoscale combustor and thermophotovoltaics (TPV). The micro-scale combustor is one part that functions as a combustion chamber that produces heat in micropower plants. Heptane is used as fuel, while the combustor combustion chamber with a diameter of 3.5 mm is made from duraluminium-quart glass tube. Combustion stability in the combustion chamber is influenced by several factors, such as temperature, geometry, and combustion chamber design. In order to maintain flame stability, mesh is added to the combustion chamber. One way to minimize heat loss in the combustion chamber is to add an insulating layer to the combustion chamber. This research aims to prove the role of adding an insulating layer in flame stability in mesoscale burners. It is necessary to add an appropriate insulating layer to minimize heat loss so that it remains stable in the mesoscale burner. This experimental test shows that the temperature distribution when adding an insulation layer with a thickness of 3 mm has a higher temperature on the outside compared to a thickness of 6 mm. Meanwhile, the temperature inside the combustor chamber with a thickness of 6 mm is superior to that with a thickness of 3 mm. The flame limit of the combustor with a mesh distance of 5 mm for liquid heptane fuel was successfully stable at an equivalent ratio of ɸ0.97 – 1.5 with a maximum speed of 31.7.
{"title":"The Effect of Insulation Thickness on Heat Transfer Characteristics and Flammability in Tube Mesoscale Combustors","authors":"Evita Leninda Fahriza Ayuni, Andinusa Rahmandhika, Daryono, Ardi Lesmawanto, Krisna Bayu Rizkyawan, Ali Mokhtar, Achmad Fauzan Hery Soegiharto","doi":"10.37934/arfmts.116.2.157171","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.157171","url":null,"abstract":"Micropower generator is a micro-scale energy source that has two main components, namely a micro/mesoscale combustor and thermophotovoltaics (TPV). The micro-scale combustor is one part that functions as a combustion chamber that produces heat in micropower plants. Heptane is used as fuel, while the combustor combustion chamber with a diameter of 3.5 mm is made from duraluminium-quart glass tube. Combustion stability in the combustion chamber is influenced by several factors, such as temperature, geometry, and combustion chamber design. In order to maintain flame stability, mesh is added to the combustion chamber. One way to minimize heat loss in the combustion chamber is to add an insulating layer to the combustion chamber. This research aims to prove the role of adding an insulating layer in flame stability in mesoscale burners. It is necessary to add an appropriate insulating layer to minimize heat loss so that it remains stable in the mesoscale burner. This experimental test shows that the temperature distribution when adding an insulation layer with a thickness of 3 mm has a higher temperature on the outside compared to a thickness of 6 mm. Meanwhile, the temperature inside the combustor chamber with a thickness of 6 mm is superior to that with a thickness of 3 mm. The flame limit of the combustor with a mesh distance of 5 mm for liquid heptane fuel was successfully stable at an equivalent ratio of ɸ0.97 – 1.5 with a maximum speed of 31.7.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"44 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141014005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.102111
Gunarjo Suryanto Budi, Sasa Kenjeres
This paper presents a study of developing a numerical turbulent model in a cavity heated from below using eddy viscosity combined with elliptic relaxation approach. The model uses a set of differential equations that consist of kinetic energy, its dissipation, variance of temperature, velocity scale and elliptic relaxation parameter, which are solved using a finite-volume and Navier-Stokes solver. The unresolved stress tensors and heat flux vectors are modelled with an algebraic formula. The discretization method is carried out by CDS, or second-order differencing scheme, and LUDS, or second-order linear upwind scheme. The model is applied to the natural convection heated from below, known as Rayleigh-Benard convection, in a two-dimensional cavity with a height-to-length aspect ratio of 1:1.5, 1:4, and 1:8. The model has been validated using numerical data from DNS (direct numerical simulation) and experiments. The model produced similar results with both DNS and experiments. It was also shown that the model can visualize the main feature of turbulent convective flow in the enclosure for various aspect ratio.
本文介绍了利用涡粘与椭圆松弛相结合的方法在一个从下往上加热的空腔中建立湍流数值模型的研究。该模型使用一组微分方程，包括动能、动能耗散、温度变化、速度尺度和椭圆松弛参数，并使用有限体积和纳维-斯托克斯求解器求解。未解决的应力张量和热通量向量用代数公式建模。离散化方法采用 CDS（二阶差分方案）和 LUDS（二阶线性上风方案）。该模型适用于高度与长度长宽比分别为 1:1.5、1:4 和 1:8 的二维空腔中自下而上受热的自然对流（即瑞利-贝纳德对流）。该模型利用 DNS（直接数值模拟）和实验的数值数据进行了验证。该模型与 DNS 和实验结果相似。实验还表明，该模型可以直观地显示不同长宽比的围护结构中湍流对流的主要特征。
{"title":"Extended Eddy-Viscosity Model to Rayleigh-Benard Convection in Cavity","authors":"Gunarjo Suryanto Budi, Sasa Kenjeres","doi":"10.37934/arfmts.116.2.102111","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.102111","url":null,"abstract":"This paper presents a study of developing a numerical turbulent model in a cavity heated from below using eddy viscosity combined with elliptic relaxation approach. The model uses a set of differential equations that consist of kinetic energy, its dissipation, variance of temperature, velocity scale and elliptic relaxation parameter, which are solved using a finite-volume and Navier-Stokes solver. The unresolved stress tensors and heat flux vectors are modelled with an algebraic formula. The discretization method is carried out by CDS, or second-order differencing scheme, and LUDS, or second-order linear upwind scheme. The model is applied to the natural convection heated from below, known as Rayleigh-Benard convection, in a two-dimensional cavity with a height-to-length aspect ratio of 1:1.5, 1:4, and 1:8. The model has been validated using numerical data from DNS (direct numerical simulation) and experiments. The model produced similar results with both DNS and experiments. It was also shown that the model can visualize the main feature of turbulent convective flow in the enclosure for various aspect ratio.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"50 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.4150
Gancang Saroja, Sugeng Rianto, Abdurrouf, S. P. Sakti, M. Nurhuda
Mesh generation is critical for obtaining accurate and detailed solutions to mesh-based numerical problems, particularly when capturing specific information within a designated area of the domain. While structured meshes offer consistency, their uniform resolution limits their ability to achieve this. Mesh stretching offers a solution by introducing non-uniform element sizes based on an analytical relationship while preserving the original mesh structure. The objective of this study is to create a hybrid mesh model that leverages the strengths of both structured and stretched meshes. A 2D rectangle with elbow edges serves as the domain. To address the requirements of CFD applications, the domain is refined by increasing element density near the boundaries and corners. Skewness, aspect ratio, and element quality are then assessed to determine the overall mesh quality. The results demonstrate that stretching the structured mesh produced a mesh with quality that meets CFD domain standards.
{"title":"Stretched Meshing in a 2D Computational Domain with Elbow Edges for CFD Applications","authors":"Gancang Saroja, Sugeng Rianto, Abdurrouf, S. P. Sakti, M. Nurhuda","doi":"10.37934/arfmts.116.2.4150","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.4150","url":null,"abstract":"Mesh generation is critical for obtaining accurate and detailed solutions to mesh-based numerical problems, particularly when capturing specific information within a designated area of the domain. While structured meshes offer consistency, their uniform resolution limits their ability to achieve this. Mesh stretching offers a solution by introducing non-uniform element sizes based on an analytical relationship while preserving the original mesh structure. The objective of this study is to create a hybrid mesh model that leverages the strengths of both structured and stretched meshes. A 2D rectangle with elbow edges serves as the domain. To address the requirements of CFD applications, the domain is refined by increasing element density near the boundaries and corners. Skewness, aspect ratio, and element quality are then assessed to determine the overall mesh quality. The results demonstrate that stretching the structured mesh produced a mesh with quality that meets CFD domain standards.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"9 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141014142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-04DOI: 10.37934/arfmts.116.2.144156
I. Buana, E. Kosasih
In the drying process there are several parameters that influence the evaporation rate. Apart from pressure and temperature, air humidity in the drying room has been shown to influence the evaporation rate. To find out how much influence air humidity has on the evaporation rate in a Vacuum Freeze Dryer (VFD) system, calculations and simulations need to be carried out. Evaporation in a VFD occurs by sublimation at evaporation conditions below the triple point of water. Ice weighing 2x10-2 kg was used as dry material to characterize the VFD process at a temperature of -10oC. The ice temperature and operating pressure are selected at conditions below the triple point so that sublimation evaporation occurs. The temperature of the drying room for heating was varied, namely (20, 25, 30)(oC) and pressure (0.5, 0.4, 0.3)(kPa). Air humidity ratio, varies at (300, 200, 100, 10, 1, 0.1, 0.01, 0.001) (kg H2O/kg dry air). The simulation is carried out in a drying room, the ice receives heat due to the temperature difference with room temperature, heat transfer occurs by radiation and diffusion. Heat is used to evaporate the ice through sublimation. The temperature of the ice upon sublimation is close to the wet bulb temperature and remains constant until the ice has completely evaporated. From the simulation it is known that changing the air humidity ratio in the drying room from 300 (kg H2O/kg dry air) to 0.001 (kg H2O/kg dry air) will increase the evaporation rate between 6.2% - 9.5%. The evaporation rate increased by 6.2% was obtained at P∞=0.3kPa, T∞=30oC. This increase in evaporation rate shortened the drying time by 0.42 hours. The evaporation rate increased by 9.5% at a pressure of P∞=0.5kPA, T∞=20oC thereby shortening the drying time by 1.03 hours. Simulations show that increasing the evaporation rate and shortening the drying time has the potential to increase the energy efficiency of the VFD. The increase in evaporation rate is influenced by operating temperature and pressure. Simulations confirmed that the evaporation rate increased when the drying chamber temperature was increased and the air pressure was decreased.
{"title":"Simulation of the Effect of Air Humidity Ratio in the Drying Room on the Rate of Material Evaporation in Vacuum Freeze Drying","authors":"I. Buana, E. Kosasih","doi":"10.37934/arfmts.116.2.144156","DOIUrl":"https://doi.org/10.37934/arfmts.116.2.144156","url":null,"abstract":"In the drying process there are several parameters that influence the evaporation rate. Apart from pressure and temperature, air humidity in the drying room has been shown to influence the evaporation rate. To find out how much influence air humidity has on the evaporation rate in a Vacuum Freeze Dryer (VFD) system, calculations and simulations need to be carried out. Evaporation in a VFD occurs by sublimation at evaporation conditions below the triple point of water. Ice weighing 2x10-2 kg was used as dry material to characterize the VFD process at a temperature of -10oC. The ice temperature and operating pressure are selected at conditions below the triple point so that sublimation evaporation occurs. The temperature of the drying room for heating was varied, namely (20, 25, 30)(oC) and pressure (0.5, 0.4, 0.3)(kPa). Air humidity ratio, varies at (300, 200, 100, 10, 1, 0.1, 0.01, 0.001) (kg H2O/kg dry air). The simulation is carried out in a drying room, the ice receives heat due to the temperature difference with room temperature, heat transfer occurs by radiation and diffusion. Heat is used to evaporate the ice through sublimation. The temperature of the ice upon sublimation is close to the wet bulb temperature and remains constant until the ice has completely evaporated. From the simulation it is known that changing the air humidity ratio in the drying room from 300 (kg H2O/kg dry air) to 0.001 (kg H2O/kg dry air) will increase the evaporation rate between 6.2% - 9.5%. The evaporation rate increased by 6.2% was obtained at P∞=0.3kPa, T∞=30oC. This increase in evaporation rate shortened the drying time by 0.42 hours. The evaporation rate increased by 9.5% at a pressure of P∞=0.5kPA, T∞=20oC thereby shortening the drying time by 1.03 hours. Simulations show that increasing the evaporation rate and shortening the drying time has the potential to increase the energy efficiency of the VFD. The increase in evaporation rate is influenced by operating temperature and pressure. Simulations confirmed that the evaporation rate increased when the drying chamber temperature was increased and the air pressure was decreased.","PeriodicalId":37460,"journal":{"name":"Journal of Advanced Research in Fluid Mechanics and Thermal Sciences","volume":"99 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141013499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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