Dawit Tafesse - Academia.edu (original) (raw)
Papers by Dawit Tafesse
Thermal Science, 2022
The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it... more The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher and on tube side it is 42% higher than the other types.
Advances in Materials Science and Engineering, Sep 5, 2022
In the current work, the experimentations have been accomplished to assess the impact of di using... more In the current work, the experimentations have been accomplished to assess the impact of di using nanosilica particles in epoxy matrix on the mechanical and thermal performance of the lu a bre reinforced epoxy composite material. e matrix and bre composition are xed as 80 : 20 throughout the study, and the nanosilica is disbanded in diversi ed volume fractions of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, respectively, while preparing lu a/epoxy/nanosilica (LES) composite samples. e mechanical characteristics, such as tensile, exural, and impact behaviour of the composite, and the thermal properties, namely, thermal stability and thermal conductivity, are examined for the LES samples. e experiments are accomplished as per the ASTM standards. e results revealed that the assimilation of nanosilica particles in epoxy has improved the mechanical and thermal characteristics of the composite signi cantly. e tensile, exural, and impact strength of the composite have been amended by 157.58%, 66.9%, and 16.5% with 1.5% addition of nanosilica in epoxy. Similarly, thermal conductivity of the composite is improved by 47.53% with the dispersion of 2.5% nanosilica in epoxy matrix. In addition, the thermal stability of the LES composite samples is substantially improved while disbanding nanosilica in epoxy matrix. However, the better results are reported for the LES composites containing 1.5% nanosilica content, compared to the next higher volume fractions of nanosilica content in epoxy matrix.
Advances in Materials Science and Engineering, Sep 2, 2022
FSW (friction stir welding) is a solid-state joining method that attracts interest from all indus... more FSW (friction stir welding) is a solid-state joining method that attracts interest from all industries. e in uence of various tool rotational speeds on the microstructure and mechanical characteristics of dissimilar pure Cu-brass joints has been investigated. e travel speed and vertical load were kept constant in the welding trials, at 40 mm/min and 10 kN, respectively, while the tool rotational speed varied from 1000 to 1400 rpm. e increase of the rotational speed to 1400 rpm resulted in degradation of the mechanical properties. e stir zone grain structure was re ned; however, the grain size was irregular. Grain re ning occurs due to a continuous and discontinuous dynamic recrystallization mechanism. In the grain interior, there were many large dislocations, identifying that incomplete recrystallization took part within the SZ. Instead, the lower rotational speed, i.e., 1000 rpm, led to more uniform grain re nement in the SZ. Moreover, in contrast to the welded zone where very ne grains exist, the base metal and thermomechanically heat-a ected zone display coarser grains. Because of the microstructural modi cation, the stir zone's mechanical characteristics were higher than the base materials, and the mechanical strength and plasticity were simultaneously upgraded. ese results indicate that the size of the grains is independent of rotational speed. And mechanical properties like hardness and impact strength decreased as the rotational speed increased.
Journal of Energy Technologies and Policy, 2019
This project entitled "Recoverable quantity of waste heat at Messebo cement factor y" has tried t... more This project entitled "Recoverable quantity of waste heat at Messebo cement factor y" has tried to quantify the amount of heat loss, the amount of energy and cost saved from the waste heat. Here both primary and secondary data collection methods were included to carry out the study. So, the projects present starts by identifying the main source of waste (which part of cement have high loss), following calculated heat lost from the identified places or machines and final calculating the possible money saved if the waste heat changed to use full form or if it recovered Successful recovery waste heat contributes to lower fuel cost, lower electricity consumption. Kiln surface zones, Preheater cyclone 4 and 5 are the main areas in which high waste was occur. From Kiln surface zones (959.13 kJ), Preheater cyclone 4 and 5(587.199 kJ) amount of heat is lost. From this lost we can recover around 62 kW power is recovered, 44155kwhr/month energy and 26492birr/month could be saved. It recommended the energy management department should invite and support others participation and to study on the heat recovery from the loosing of energy and to study on the alternative energy sources of the company.
Thermal Science, 2021
The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it... more The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher...
Materials Today: Proceedings, 2021
Abstract In this investigational study was extremely focused on optimized the Material Removal Ra... more Abstract In this investigational study was extremely focused on optimized the Material Removal Rate (MRR) analysis of LM13/Graphene AMCs with three machining variables. The LM13/10 wt%Graphene AMCs are prepared via the melt stir casting process. The conventional machining (drilling) method was to investigate the machinability features. In this experimental analysis, drilling speed (1000, 1200, 1400 rpm), drilling feed (40, 80, 120 mm/min) and drilling time (2, 4, 6 min) were applied as input process variables for the drilling operation. The input variables were to test responses such as the MRR. Taguchi optimization, contour map, and variance test also stated.
Polymer Engineering & Science, 2018
In this article, a kind of degradable composite was prepared from bamboo fiber (BF), poly lactic ... more In this article, a kind of degradable composite was prepared from bamboo fiber (BF), poly lactic acid (PLA), and polypropylene (PP). The mechanical and thermal properties were characterized by the universal testing machine, thermogravimetric analysis, differential scanning calorimetry. In order to improve the compability between BF and polymer matrix several modification on the surface of BF were explored and compared. Moreover, a compatibilizer (maleated PP) was applied to further increase compatibility between the fiber and matrix. It is found that the thermal stability of BF/PP/PLA composites decreased with the increase of maleated polypropylene (MAPP) content. When 5% MAPP was used the tensile strength, flexural strength, and impact strength of composites reached 33.73, 47.18 MPa, and 3.15 KJ/m 2 , with an increase by 13, 11.7, and 23.5%, respectively, compared with the composites without MAPP. The improvement of mechanical properties is attributed to the fact that irregular grooves and cracks induced by the modification of BF facilitate the infiltration of polymer into fiber due to the strong capillary effect. Furthermore, BF/PP/PLA composites are potential to be used in 3D printing. POLYM.
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Amalgamation of nanoparticles with the conventional/alternative fuels is an attractive approach w... more Amalgamation of nanoparticles with the conventional/alternative fuels is an attractive approach which can enhance the working characteristics of CI engines. The critical issues such as stability, clogging, increased NOx, and high consumption rate attached with the long-term usage of diesel/biodiesel and with their blends restricts their usage as a potential substitute in the diesel engine. This review work emphasizes the research economy on utilizing the application of different metal oxide, magnetic, carbon and hybridized based nano-materials as a fuel-borne additive. Nano fuel comprises a micro-sized particle ranging from 1 to 100nm in size doped inside the base fluid (diesel/biodiesel) using the process of ultrasonication. The nano fuel has a higher surface to volume ratio, and enhanced heat and mass transfer properties act as a catalyst, improves the combustion process and the performance characteristics such as thermal efficiency, specific fuel consumptions of the diesel engine. Based on the outcome collected from the previously published work, it has been concluded that mixing of nanoadditives has a significant effect on the engine parameters. The review also highlights that the improvement in the injection timing, enhancement in the physicochemical properties and cold flow properties such as viscosity, calorific value, flash point, fire point is also noted depending on the dosage of nanoparticles.
Advances in Materials Science and Engineering, Sep 2, 2022
FSW (friction stir welding) is a solid-state joining method that attracts interest from all indus... more FSW (friction stir welding) is a solid-state joining method that attracts interest from all industries. e in uence of various tool rotational speeds on the microstructure and mechanical characteristics of dissimilar pure Cu-brass joints has been investigated. e travel speed and vertical load were kept constant in the welding trials, at 40 mm/min and 10 kN, respectively, while the tool rotational speed varied from 1000 to 1400 rpm. e increase of the rotational speed to 1400 rpm resulted in degradation of the mechanical properties. e stir zone grain structure was re ned; however, the grain size was irregular. Grain re ning occurs due to a continuous and discontinuous dynamic recrystallization mechanism. In the grain interior, there were many large dislocations, identifying that incomplete recrystallization took part within the SZ. Instead, the lower rotational speed, i.e., 1000 rpm, led to more uniform grain re nement in the SZ. Moreover, in contrast to the welded zone where very ne grains exist, the base metal and thermomechanically heat-a ected zone display coarser grains. Because of the microstructural modi cation, the stir zone's mechanical characteristics were higher than the base materials, and the mechanical strength and plasticity were simultaneously upgraded. ese results indicate that the size of the grains is independent of rotational speed. And mechanical properties like hardness and impact strength decreased as the rotational speed increased.
Advances in Materials Science and Engineering
In the current work, the experimentations have been accomplished to assess the impact of diffusin... more In the current work, the experimentations have been accomplished to assess the impact of diffusing nanosilica particles in epoxy matrix on the mechanical and thermal performance of the luffa fibre reinforced epoxy composite material. The matrix and fibre composition are fixed as 80 : 20 throughout the study, and the nanosilica is disbanded in diversified volume fractions of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, respectively, while preparing luffa/epoxy/nanosilica (LES) composite samples. The mechanical characteristics, such as tensile, flexural, and impact behaviour of the composite, and the thermal properties, namely, thermal stability and thermal conductivity, are examined for the LES samples. The experiments are accomplished as per the ASTM standards. The results revealed that the assimilation of nanosilica particles in epoxy has improved the mechanical and thermal characteristics of the composite significantly. The tensile, flexural, and impact strength of the composite have bee...
Journal of Nanomaterials
The current work investigates the performance of cylindrical-shaped sintered wick heat pipe at di... more The current work investigates the performance of cylindrical-shaped sintered wick heat pipe at different orientations, numerically. The results are compared and validated with the experimental findings. The study is extended by using a nanofluid (comprising nano-Curo in deionized water) as a working fluid and the thermal performance of heat pipe with deionized (DI) water has been compared with that of heat pipe with nanofluid (containing various concentrations of CuO nanoparticles in DI water). During the investigation, the nanofluid with 1.0 weight fraction of CuO nanopaticles found to be optimum, which has produced the better results. The numerical analysis has been carried out to study the temperature difference, fluid velocity, and pressure drop of the sintered wick heat pipe using the commercial CFD software, Ansys Fluent R14.5. The computational results are observed to be much closer to the experimental data, and the vapor velocity at the heat pipe’s core has been determined t...
한국hci학회 학술대회, Feb 1, 2014
Journal of the Korea Computer Graphics Society, 2014
스마트폰의 전면 및 후면 카메라를 이용하여 동시에 획득한 전경 이미지와 배경 이미지에서, 전경 이미지의 일부분인 전경 물체를 추출하여 배경 이미지에 합성하는 방법을 제시한다.... more 스마트폰의 전면 및 후면 카메라를 이용하여 동시에 획득한 전경 이미지와 배경 이미지에서, 전경 이미지의 일부분인 전경 물체를 추출하여 배경 이미지에 합성하는 방법을 제시한다. 최근의 고사양 스마트폰은 대개 두 개의 카메라를 가지고 있고, 사진을 촬영하는 과정에서 미리보기 화면을 제공한다. 전면 카메라로부터 전경 이미지를 획득하는 과정에서 미리보기 화면의 비디오에 대한 옵티컬 플로우를 이용하여 전경 물체를 추출한다. 추출된 전경 물체와 배경 화면을 단순히 합성한 후, 전경 물체와 배경화면의 경계에서 가중치 경계 블렌딩을 이용하여 시각적으로 부드러운 경계를 갖는 합성을 수행한다. 화소 수준의 조밀한 옵티컬 플로우의 계산은 고사양의 스마트폰에서도 상당히 느리기 때문에, 전경 물체 추출을 위한 마스크의 계산을 저해상도에서 수행하여 계산시간을 크게 절약 할 수 있다. 실험적 결과에 의하면 제안하는 방법은 더 적은 계산 시간을 사용하며, 널리 사용되는 Poisson 이미지 합성 방법에 비하여 시각적으로 더 우수한 결과를 얻을 수 있다. 제안하는 방법은 Poisson 이미지 합성 방법에서 자주 관찰되는 색 번짐 결점을 가중치 경계 블렌딩을 이용하여 제한적인 수준에서 극복할 수 있다.
Advances in Materials Science and Engineering
By modifying the angle of tilt of 2 distinct tool pin shapes, both tapered with and without threa... more By modifying the angle of tilt of 2 distinct tool pin shapes, both tapered with and without threaded structures, TPT tool pin with threads and TPNT tool pin with no threads, the mechanical behaviour and microstructural attributes were examined for the joints of AZ91B alloy formed by friction stir welding. Spindle torque and unique forces operating laterally and axially (referred to as Y-force and X-force, respectively) were created at the junction of the tool and plate, which were monitored and assessed in order to know the influence of degrees of tilt. When the tool’s angle of tilt advances, torque and forces of the spindle also show an increasing trend that is important to friction stir welding. The spindle torque and Y-force produced by the TPT tool are higher than those of the TPNT tool, whereas the X-force associated with the TPT tool is less. Discrepancies in forces grow along the concurrent increase in the angle of tilt for the TPNT as well as TPT tools, exhibiting opposite b...
Advances in Materials Science and Engineering
Here, the investigation is spotlighted on the aluminium alloy from the waste materials of the aut... more Here, the investigation is spotlighted on the aluminium alloy from the waste materials of the automobile bumpers which is a reinforced metal matrix composite created with 5 percentage of nickel and 5 percentage of magnesium oxide through the stir casting method. The stir casting process inputs parameters such as pressure of squeezing, time of squeezing, and speed of stirrer which were optimized based on the two mechanical properties’ outcome such as the tensile strength (TS) and Rockwell hardness. There are nine different experiments which were conducted based on the L9 array. The Taguchi method is used to identify the optimum input values for the greatest result of the processing condition by Minitab software. The responses-based parameters were ordered based on the rank identified through the investigational effects. Finally, the optimized input consideration values and the linear equations are recommended for both the considered outputs as conclusions.
Advances in Materials Science and Engineering, 2021
Automobile industries were ready to recycle the waste old parts as well as the damaged parts of t... more Automobile industries were ready to recycle the waste old parts as well as the damaged parts of the old vehicles as much as possible. This study mainly focused on the recycling of the waste and damaged aluminium frames of the automobile bodies. These aluminium-based frames only collected the metal matrix composite created by reinforcement of 3% silicon carbide (SiC) and 3% high carbon steel. The stir casting method is chosen to make the composites. Optimization is done by Taguchi ANOVA technique. Three input parameters such as stir speed, time of squeeze, and the temperature of the preheating were considered. The outputs such as compressive strength and porosity were experimentally measured with the combination of nine (L9) experimental trails. The measured experimental results were analyzed and optimized with the help of Taguchi technique with different plots for clear identification. The optimized parameters based on low porosity and high compressive strength were recommended for ...
Materials Today: Proceedings, 2021
Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that ca... more Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that can be converted to useful product. By this study, those free raw materials of waste plastics are collected and recycled to produce sand plastic composite brick (SPCB). SPCB of characteristic similar to conventional sand-cement brick was produced using simple technology of compression molding by melt blending technique. Best possible mixture composition of sand and plastic weight percentage for higher compressive strength is determined using optimum mixture design of experiment (DOE). Using Design Expert software, a quadratic model was setup as function of the Sand-Plastic Composite element weight percentage. The setup model was confirmed experimentally through ANOVA table and fit summary. Diagnostic case statics and graphical representations of the model were also investigated by using adjusted R-Squared, predicted R-Squared, DFFITS and Cook's D graphs. In addition, the effects of sand and plastic weight percentage on compressive strength variation were also studied. Finally, optimum percentage of mixtures of sand and plastic that would yield maximum compressive strength is predicted from analysis of graph. Maximum compressive strength about 4.95 N/mm2 was obtained when the plastic weight percent of 60% (40 wt% LDPE and 20 wt% HDPE) was melt blended with sand weight percent of 40% (25% of sand size of 1.18 mm and 15% of sand size 0.5 mm). When waste plastic content was greater than 70%; it affects the response negatively this was result from the impurities content. Sand has negative effect on compressive strength when its wt. % is greater than 42% this was due to pore created in sample of SPC that result from non-coherent mix of plastic and sand. The authors concluded that, inventions like SPCB from waste plastics have many environmental and cost advantages. So, mixture Design of Experiment can be used as an alternative mixture design method in order to get better mechanical property product of sand plastic composites.
Materials Today: Proceedings, 2021
Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that ca... more Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that can be converted to useful product. By this study, those free raw materials of waste plastics are collected and recycled to produce sand plastic composite brick (SPCB). SPCB of characteristic similar to conventional sand-cement brick was produced using simple technology of compression molding by melt blending technique. Best possible mixture composition of sand and plastic weight percentage for higher compressive strength is determined using optimum mixture design of experiment (DOE). Using Design Expert software, a quadratic model was setup as function of the Sand-Plastic Composite element weight percentage. The setup model was confirmed experimentally through ANOVA table and fit summary. Diagnostic case statics and graphical representations of the model were also investigated by using adjusted R-Squared, predicted R-Squared, DFFITS and Cook's D graphs. In addition, the effects of sand and plastic weight percentage on compressive strength variation were also studied. Finally, optimum percentage of mixtures of sand and plastic that would yield maximum compressive strength is predicted from analysis of graph. Maximum compressive strength about 4.95 N/mm2 was obtained when the plastic weight percent of 60% (40 wt% LDPE and 20 wt% HDPE) was melt blended with sand weight percent of 40% (25% of sand size of 1.18 mm and 15% of sand size 0.5 mm). When waste plastic content was greater than 70%; it affects the response negatively this was result from the impurities content. Sand has negative effect on compressive strength when its wt. % is greater than 42% this was due to pore created in sample of SPC that result from non-coherent mix of plastic and sand. The authors concluded that, inventions like SPCB from waste plastics have many environmental and cost advantages. So, mixture Design of Experiment can be used as an alternative mixture design method in order to get better mechanical property product of sand plastic composites.
Recent Advances in Sustainable Technologies, 2021
Materials Today: Proceedings
Thermal Science, 2022
The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it... more The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher and on tube side it is 42% higher than the other types.
Advances in Materials Science and Engineering, Sep 5, 2022
In the current work, the experimentations have been accomplished to assess the impact of di using... more In the current work, the experimentations have been accomplished to assess the impact of di using nanosilica particles in epoxy matrix on the mechanical and thermal performance of the lu a bre reinforced epoxy composite material. e matrix and bre composition are xed as 80 : 20 throughout the study, and the nanosilica is disbanded in diversi ed volume fractions of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, respectively, while preparing lu a/epoxy/nanosilica (LES) composite samples. e mechanical characteristics, such as tensile, exural, and impact behaviour of the composite, and the thermal properties, namely, thermal stability and thermal conductivity, are examined for the LES samples. e experiments are accomplished as per the ASTM standards. e results revealed that the assimilation of nanosilica particles in epoxy has improved the mechanical and thermal characteristics of the composite signi cantly. e tensile, exural, and impact strength of the composite have been amended by 157.58%, 66.9%, and 16.5% with 1.5% addition of nanosilica in epoxy. Similarly, thermal conductivity of the composite is improved by 47.53% with the dispersion of 2.5% nanosilica in epoxy matrix. In addition, the thermal stability of the LES composite samples is substantially improved while disbanding nanosilica in epoxy matrix. However, the better results are reported for the LES composites containing 1.5% nanosilica content, compared to the next higher volume fractions of nanosilica content in epoxy matrix.
Advances in Materials Science and Engineering, Sep 2, 2022
FSW (friction stir welding) is a solid-state joining method that attracts interest from all indus... more FSW (friction stir welding) is a solid-state joining method that attracts interest from all industries. e in uence of various tool rotational speeds on the microstructure and mechanical characteristics of dissimilar pure Cu-brass joints has been investigated. e travel speed and vertical load were kept constant in the welding trials, at 40 mm/min and 10 kN, respectively, while the tool rotational speed varied from 1000 to 1400 rpm. e increase of the rotational speed to 1400 rpm resulted in degradation of the mechanical properties. e stir zone grain structure was re ned; however, the grain size was irregular. Grain re ning occurs due to a continuous and discontinuous dynamic recrystallization mechanism. In the grain interior, there were many large dislocations, identifying that incomplete recrystallization took part within the SZ. Instead, the lower rotational speed, i.e., 1000 rpm, led to more uniform grain re nement in the SZ. Moreover, in contrast to the welded zone where very ne grains exist, the base metal and thermomechanically heat-a ected zone display coarser grains. Because of the microstructural modi cation, the stir zone's mechanical characteristics were higher than the base materials, and the mechanical strength and plasticity were simultaneously upgraded. ese results indicate that the size of the grains is independent of rotational speed. And mechanical properties like hardness and impact strength decreased as the rotational speed increased.
Journal of Energy Technologies and Policy, 2019
This project entitled "Recoverable quantity of waste heat at Messebo cement factor y" has tried t... more This project entitled "Recoverable quantity of waste heat at Messebo cement factor y" has tried to quantify the amount of heat loss, the amount of energy and cost saved from the waste heat. Here both primary and secondary data collection methods were included to carry out the study. So, the projects present starts by identifying the main source of waste (which part of cement have high loss), following calculated heat lost from the identified places or machines and final calculating the possible money saved if the waste heat changed to use full form or if it recovered Successful recovery waste heat contributes to lower fuel cost, lower electricity consumption. Kiln surface zones, Preheater cyclone 4 and 5 are the main areas in which high waste was occur. From Kiln surface zones (959.13 kJ), Preheater cyclone 4 and 5(587.199 kJ) amount of heat is lost. From this lost we can recover around 62 kW power is recovered, 44155kwhr/month energy and 26492birr/month could be saved. It recommended the energy management department should invite and support others participation and to study on the heat recovery from the loosing of energy and to study on the alternative energy sources of the company.
Thermal Science, 2021
The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it... more The inclusion of baffles in a double pipe heat exchanger is becoming increasingly important as it improves the heat exchanger's performance. The CFD analysis is used in this paper to investigate the performance of double pipe heat exchangers with and without helical baffles on both shell tube sides. The 3-D CFD model was created in Solid Works, and the FloEFD software was used to analyze the conjugate heat transfer between the heat exchanger's tube and shell sides. Heat transfer characteristic like outlet temperature of shell and tube are investigated along with pressure drop on shell and tube side. Based on CFD results of double pipe heat exchanger with helical baffle on both shell side and tube side (Type 4) gives the better results than the other type of heat exchangers with an increased pressure drop than the others, results reveals that Type 4 outlet temperature of shell side is 8% higher and on tube side it is 5.5% higher, also pressure drop on shell side is 12% higher...
Materials Today: Proceedings, 2021
Abstract In this investigational study was extremely focused on optimized the Material Removal Ra... more Abstract In this investigational study was extremely focused on optimized the Material Removal Rate (MRR) analysis of LM13/Graphene AMCs with three machining variables. The LM13/10 wt%Graphene AMCs are prepared via the melt stir casting process. The conventional machining (drilling) method was to investigate the machinability features. In this experimental analysis, drilling speed (1000, 1200, 1400 rpm), drilling feed (40, 80, 120 mm/min) and drilling time (2, 4, 6 min) were applied as input process variables for the drilling operation. The input variables were to test responses such as the MRR. Taguchi optimization, contour map, and variance test also stated.
Polymer Engineering & Science, 2018
In this article, a kind of degradable composite was prepared from bamboo fiber (BF), poly lactic ... more In this article, a kind of degradable composite was prepared from bamboo fiber (BF), poly lactic acid (PLA), and polypropylene (PP). The mechanical and thermal properties were characterized by the universal testing machine, thermogravimetric analysis, differential scanning calorimetry. In order to improve the compability between BF and polymer matrix several modification on the surface of BF were explored and compared. Moreover, a compatibilizer (maleated PP) was applied to further increase compatibility between the fiber and matrix. It is found that the thermal stability of BF/PP/PLA composites decreased with the increase of maleated polypropylene (MAPP) content. When 5% MAPP was used the tensile strength, flexural strength, and impact strength of composites reached 33.73, 47.18 MPa, and 3.15 KJ/m 2 , with an increase by 13, 11.7, and 23.5%, respectively, compared with the composites without MAPP. The improvement of mechanical properties is attributed to the fact that irregular grooves and cracks induced by the modification of BF facilitate the infiltration of polymer into fiber due to the strong capillary effect. Furthermore, BF/PP/PLA composites are potential to be used in 3D printing. POLYM.
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019
Amalgamation of nanoparticles with the conventional/alternative fuels is an attractive approach w... more Amalgamation of nanoparticles with the conventional/alternative fuels is an attractive approach which can enhance the working characteristics of CI engines. The critical issues such as stability, clogging, increased NOx, and high consumption rate attached with the long-term usage of diesel/biodiesel and with their blends restricts their usage as a potential substitute in the diesel engine. This review work emphasizes the research economy on utilizing the application of different metal oxide, magnetic, carbon and hybridized based nano-materials as a fuel-borne additive. Nano fuel comprises a micro-sized particle ranging from 1 to 100nm in size doped inside the base fluid (diesel/biodiesel) using the process of ultrasonication. The nano fuel has a higher surface to volume ratio, and enhanced heat and mass transfer properties act as a catalyst, improves the combustion process and the performance characteristics such as thermal efficiency, specific fuel consumptions of the diesel engine. Based on the outcome collected from the previously published work, it has been concluded that mixing of nanoadditives has a significant effect on the engine parameters. The review also highlights that the improvement in the injection timing, enhancement in the physicochemical properties and cold flow properties such as viscosity, calorific value, flash point, fire point is also noted depending on the dosage of nanoparticles.
Advances in Materials Science and Engineering, Sep 2, 2022
FSW (friction stir welding) is a solid-state joining method that attracts interest from all indus... more FSW (friction stir welding) is a solid-state joining method that attracts interest from all industries. e in uence of various tool rotational speeds on the microstructure and mechanical characteristics of dissimilar pure Cu-brass joints has been investigated. e travel speed and vertical load were kept constant in the welding trials, at 40 mm/min and 10 kN, respectively, while the tool rotational speed varied from 1000 to 1400 rpm. e increase of the rotational speed to 1400 rpm resulted in degradation of the mechanical properties. e stir zone grain structure was re ned; however, the grain size was irregular. Grain re ning occurs due to a continuous and discontinuous dynamic recrystallization mechanism. In the grain interior, there were many large dislocations, identifying that incomplete recrystallization took part within the SZ. Instead, the lower rotational speed, i.e., 1000 rpm, led to more uniform grain re nement in the SZ. Moreover, in contrast to the welded zone where very ne grains exist, the base metal and thermomechanically heat-a ected zone display coarser grains. Because of the microstructural modi cation, the stir zone's mechanical characteristics were higher than the base materials, and the mechanical strength and plasticity were simultaneously upgraded. ese results indicate that the size of the grains is independent of rotational speed. And mechanical properties like hardness and impact strength decreased as the rotational speed increased.
Advances in Materials Science and Engineering
In the current work, the experimentations have been accomplished to assess the impact of diffusin... more In the current work, the experimentations have been accomplished to assess the impact of diffusing nanosilica particles in epoxy matrix on the mechanical and thermal performance of the luffa fibre reinforced epoxy composite material. The matrix and fibre composition are fixed as 80 : 20 throughout the study, and the nanosilica is disbanded in diversified volume fractions of 0%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%, respectively, while preparing luffa/epoxy/nanosilica (LES) composite samples. The mechanical characteristics, such as tensile, flexural, and impact behaviour of the composite, and the thermal properties, namely, thermal stability and thermal conductivity, are examined for the LES samples. The experiments are accomplished as per the ASTM standards. The results revealed that the assimilation of nanosilica particles in epoxy has improved the mechanical and thermal characteristics of the composite significantly. The tensile, flexural, and impact strength of the composite have bee...
Journal of Nanomaterials
The current work investigates the performance of cylindrical-shaped sintered wick heat pipe at di... more The current work investigates the performance of cylindrical-shaped sintered wick heat pipe at different orientations, numerically. The results are compared and validated with the experimental findings. The study is extended by using a nanofluid (comprising nano-Curo in deionized water) as a working fluid and the thermal performance of heat pipe with deionized (DI) water has been compared with that of heat pipe with nanofluid (containing various concentrations of CuO nanoparticles in DI water). During the investigation, the nanofluid with 1.0 weight fraction of CuO nanopaticles found to be optimum, which has produced the better results. The numerical analysis has been carried out to study the temperature difference, fluid velocity, and pressure drop of the sintered wick heat pipe using the commercial CFD software, Ansys Fluent R14.5. The computational results are observed to be much closer to the experimental data, and the vapor velocity at the heat pipe’s core has been determined t...
한국hci학회 학술대회, Feb 1, 2014
Journal of the Korea Computer Graphics Society, 2014
스마트폰의 전면 및 후면 카메라를 이용하여 동시에 획득한 전경 이미지와 배경 이미지에서, 전경 이미지의 일부분인 전경 물체를 추출하여 배경 이미지에 합성하는 방법을 제시한다.... more 스마트폰의 전면 및 후면 카메라를 이용하여 동시에 획득한 전경 이미지와 배경 이미지에서, 전경 이미지의 일부분인 전경 물체를 추출하여 배경 이미지에 합성하는 방법을 제시한다. 최근의 고사양 스마트폰은 대개 두 개의 카메라를 가지고 있고, 사진을 촬영하는 과정에서 미리보기 화면을 제공한다. 전면 카메라로부터 전경 이미지를 획득하는 과정에서 미리보기 화면의 비디오에 대한 옵티컬 플로우를 이용하여 전경 물체를 추출한다. 추출된 전경 물체와 배경 화면을 단순히 합성한 후, 전경 물체와 배경화면의 경계에서 가중치 경계 블렌딩을 이용하여 시각적으로 부드러운 경계를 갖는 합성을 수행한다. 화소 수준의 조밀한 옵티컬 플로우의 계산은 고사양의 스마트폰에서도 상당히 느리기 때문에, 전경 물체 추출을 위한 마스크의 계산을 저해상도에서 수행하여 계산시간을 크게 절약 할 수 있다. 실험적 결과에 의하면 제안하는 방법은 더 적은 계산 시간을 사용하며, 널리 사용되는 Poisson 이미지 합성 방법에 비하여 시각적으로 더 우수한 결과를 얻을 수 있다. 제안하는 방법은 Poisson 이미지 합성 방법에서 자주 관찰되는 색 번짐 결점을 가중치 경계 블렌딩을 이용하여 제한적인 수준에서 극복할 수 있다.
Advances in Materials Science and Engineering
By modifying the angle of tilt of 2 distinct tool pin shapes, both tapered with and without threa... more By modifying the angle of tilt of 2 distinct tool pin shapes, both tapered with and without threaded structures, TPT tool pin with threads and TPNT tool pin with no threads, the mechanical behaviour and microstructural attributes were examined for the joints of AZ91B alloy formed by friction stir welding. Spindle torque and unique forces operating laterally and axially (referred to as Y-force and X-force, respectively) were created at the junction of the tool and plate, which were monitored and assessed in order to know the influence of degrees of tilt. When the tool’s angle of tilt advances, torque and forces of the spindle also show an increasing trend that is important to friction stir welding. The spindle torque and Y-force produced by the TPT tool are higher than those of the TPNT tool, whereas the X-force associated with the TPT tool is less. Discrepancies in forces grow along the concurrent increase in the angle of tilt for the TPNT as well as TPT tools, exhibiting opposite b...
Advances in Materials Science and Engineering
Here, the investigation is spotlighted on the aluminium alloy from the waste materials of the aut... more Here, the investigation is spotlighted on the aluminium alloy from the waste materials of the automobile bumpers which is a reinforced metal matrix composite created with 5 percentage of nickel and 5 percentage of magnesium oxide through the stir casting method. The stir casting process inputs parameters such as pressure of squeezing, time of squeezing, and speed of stirrer which were optimized based on the two mechanical properties’ outcome such as the tensile strength (TS) and Rockwell hardness. There are nine different experiments which were conducted based on the L9 array. The Taguchi method is used to identify the optimum input values for the greatest result of the processing condition by Minitab software. The responses-based parameters were ordered based on the rank identified through the investigational effects. Finally, the optimized input consideration values and the linear equations are recommended for both the considered outputs as conclusions.
Advances in Materials Science and Engineering, 2021
Automobile industries were ready to recycle the waste old parts as well as the damaged parts of t... more Automobile industries were ready to recycle the waste old parts as well as the damaged parts of the old vehicles as much as possible. This study mainly focused on the recycling of the waste and damaged aluminium frames of the automobile bodies. These aluminium-based frames only collected the metal matrix composite created by reinforcement of 3% silicon carbide (SiC) and 3% high carbon steel. The stir casting method is chosen to make the composites. Optimization is done by Taguchi ANOVA technique. Three input parameters such as stir speed, time of squeeze, and the temperature of the preheating were considered. The outputs such as compressive strength and porosity were experimentally measured with the combination of nine (L9) experimental trails. The measured experimental results were analyzed and optimized with the help of Taguchi technique with different plots for clear identification. The optimized parameters based on low porosity and high compressive strength were recommended for ...
Materials Today: Proceedings, 2021
Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that ca... more Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that can be converted to useful product. By this study, those free raw materials of waste plastics are collected and recycled to produce sand plastic composite brick (SPCB). SPCB of characteristic similar to conventional sand-cement brick was produced using simple technology of compression molding by melt blending technique. Best possible mixture composition of sand and plastic weight percentage for higher compressive strength is determined using optimum mixture design of experiment (DOE). Using Design Expert software, a quadratic model was setup as function of the Sand-Plastic Composite element weight percentage. The setup model was confirmed experimentally through ANOVA table and fit summary. Diagnostic case statics and graphical representations of the model were also investigated by using adjusted R-Squared, predicted R-Squared, DFFITS and Cook's D graphs. In addition, the effects of sand and plastic weight percentage on compressive strength variation were also studied. Finally, optimum percentage of mixtures of sand and plastic that would yield maximum compressive strength is predicted from analysis of graph. Maximum compressive strength about 4.95 N/mm2 was obtained when the plastic weight percent of 60% (40 wt% LDPE and 20 wt% HDPE) was melt blended with sand weight percent of 40% (25% of sand size of 1.18 mm and 15% of sand size 0.5 mm). When waste plastic content was greater than 70%; it affects the response negatively this was result from the impurities content. Sand has negative effect on compressive strength when its wt. % is greater than 42% this was due to pore created in sample of SPC that result from non-coherent mix of plastic and sand. The authors concluded that, inventions like SPCB from waste plastics have many environmental and cost advantages. So, mixture Design of Experiment can be used as an alternative mixture design method in order to get better mechanical property product of sand plastic composites.
Materials Today: Proceedings, 2021
Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that ca... more Abstract Nowadays Plastic wastes are a major environmental concern and free raw materials that can be converted to useful product. By this study, those free raw materials of waste plastics are collected and recycled to produce sand plastic composite brick (SPCB). SPCB of characteristic similar to conventional sand-cement brick was produced using simple technology of compression molding by melt blending technique. Best possible mixture composition of sand and plastic weight percentage for higher compressive strength is determined using optimum mixture design of experiment (DOE). Using Design Expert software, a quadratic model was setup as function of the Sand-Plastic Composite element weight percentage. The setup model was confirmed experimentally through ANOVA table and fit summary. Diagnostic case statics and graphical representations of the model were also investigated by using adjusted R-Squared, predicted R-Squared, DFFITS and Cook's D graphs. In addition, the effects of sand and plastic weight percentage on compressive strength variation were also studied. Finally, optimum percentage of mixtures of sand and plastic that would yield maximum compressive strength is predicted from analysis of graph. Maximum compressive strength about 4.95 N/mm2 was obtained when the plastic weight percent of 60% (40 wt% LDPE and 20 wt% HDPE) was melt blended with sand weight percent of 40% (25% of sand size of 1.18 mm and 15% of sand size 0.5 mm). When waste plastic content was greater than 70%; it affects the response negatively this was result from the impurities content. Sand has negative effect on compressive strength when its wt. % is greater than 42% this was due to pore created in sample of SPC that result from non-coherent mix of plastic and sand. The authors concluded that, inventions like SPCB from waste plastics have many environmental and cost advantages. So, mixture Design of Experiment can be used as an alternative mixture design method in order to get better mechanical property product of sand plastic composites.
Recent Advances in Sustainable Technologies, 2021
Materials Today: Proceedings