This document discusses numerical simulations of heat transfer in an annulus tube with internal fins. The simulations solve the governing equations for mass, momentum, energy and turbulence using a k-ε model. Various fin configurations are analyzed by varying the number, shape and size of fins. The results show that heat transfer increases with fin number and height. Trapezoidal fins have higher heat transfer than other shapes. The study aims to determine the optimal fin design for maximum thermal performance in the annulus tube.
The results show that, with proper selection of physical parameters, significant heat transfer
enhancements and pressure drop reductions can be achieved simultaneously with porous pin fins and
the overall heat transfer performances in porous pin fin channels are much better than those in
traditional solid pin fin channels. The effects of pore density are significant. As PPI increases, the
pressure drops and heat fluxes in porous pin fin channels increase while the overall heat transfer
efficiencies decrease and the maximal overall heat transfer efficiencies are obtained at PPI 20.
Furthermore, the effects of pin fin form are also remarkable. With the same physical parameters, the
overall heat transfer efficiencies in the long elliptic porous pin fin channels are the highest while they
are the lowest in the short elliptic porous pin fin channels
Exploring the Use of Computation Fluid Dynamics to Model a T-Junction for UM ...Doug Kripke
1) This document discusses using computational fluid dynamics (CFD) to model a T-junction where hot and cold fluid flows combine. Specifically, it will compare the realizable and standard k-ε turbulence models in replicating experimental velocity field measurements of water in a T-junction.
2) Extensive previous water experiments on a T-junction characterized the thermal striping phenomenon and measured velocity and temperature distributions. This project will use those experimental conditions and measurements for validation of CFD simulations.
3) Reynolds number calculations confirmed the flows are fully turbulent, validating the use of turbulence models. The CFD model setup and boundary conditions aimed to replicate the previous experimental conditions for validation purposes.
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
Study on Thermal and Hydrodynamic Indexes of a Nanofluid Flow in a Micro Heat...A Behzadmehr
The paper numerically presents laminar forced convection of a nanofluid flowing in a duct at microscale.
Results were compared with both analytical and experimental data and observed good concordance with
previous studies available in the literature. Influences of Brinkman and Reynolds number on thermal and
hydrodynamic indexes have been investigated. For a given nanofluid, no change in efficiency (heat dissipation
to pumping power) was observed with an increasing in Reynolds number. It was shown that the pressure was
decrease with an increase in Brinkman number. Dependency of Nu increment changes with substrate material.
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
This document compares the design of a shell and tube heat exchanger with baffles using four different methods: 1) Kern's theoretical method, 2) ASPEN simulation software, 3) HTRI simulation software, and 4) SOLIDWORKS simulation software. The same input parameters were used to design a shell and tube heat exchanger with single segmental baffles in each method. The results from all four methods for shell side pressure drop and heat transfer coefficient were found to be in close agreement. The theoretical Kern method design results closely matched the simulation software results, showing proven theoretical methods can accurately model shell and tube heat exchanger performance.
Experimental analysis of heat transfer enhancementin circulariaemedu
This document summarizes an experimental study on enhancing heat transfer in a circular double tube heat exchanger using rectangular inserts. Air was passed through the inner tube while hot water flowed through the outer tube. Heat transfer coefficients and friction factors were determined for the plain tube and with inserts. The results showed that heat transfer was enhanced by 0.9 to 1.9 times with the inserts due to flow disruption, while friction factors increased by 1 to 1.7 times. Heat transfer coefficients increased with Reynolds number whereas friction factors decreased. Validation experiments on a plain tube agreed well with theoretical predictions within 10% uncertainty.
1) The document discusses CFD studies conducted to analyze heat transfer in boiler tubes with different helical rifled geometries.
2) Temperature distributions within plain and rifled tubes were modeled and compared, showing that rifled tubes achieved higher temperatures than plain tubes. Triangular rifled geometry performed best, raising water temperature from 300K to 412K.
3) Rifled geometries enhance heat transfer through inducing turbulence in flow, increasing heat transfer surface area and allowing more uniform heating within the tubes. Proper tube geometry selection can significantly improve boiler performance.
Numerical Analysis of Heat Transfer Enhancement in Pipe-inPipe Helical Coiled...iosrjce
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow). The results show that overall heat transfer coefficients increase with increasing inner Dean number and mass flow rates. Heat transfer rates also increase with higher inner mass flow rates. Counter flow configuration provides better heat transfer than parallel flow. Increasing the inner tube size decreases the total heat transfer rate due to a reduction in annulus cross-sectional area. Measured inner Nusselt numbers agree reasonably well with existing correlations.
The results show that, with proper selection of physical parameters, significant heat transfer
enhancements and pressure drop reductions can be achieved simultaneously with porous pin fins and
the overall heat transfer performances in porous pin fin channels are much better than those in
traditional solid pin fin channels. The effects of pore density are significant. As PPI increases, the
pressure drops and heat fluxes in porous pin fin channels increase while the overall heat transfer
efficiencies decrease and the maximal overall heat transfer efficiencies are obtained at PPI 20.
Furthermore, the effects of pin fin form are also remarkable. With the same physical parameters, the
overall heat transfer efficiencies in the long elliptic porous pin fin channels are the highest while they
are the lowest in the short elliptic porous pin fin channels
Exploring the Use of Computation Fluid Dynamics to Model a T-Junction for UM ...Doug Kripke
1) This document discusses using computational fluid dynamics (CFD) to model a T-junction where hot and cold fluid flows combine. Specifically, it will compare the realizable and standard k-ε turbulence models in replicating experimental velocity field measurements of water in a T-junction.
2) Extensive previous water experiments on a T-junction characterized the thermal striping phenomenon and measured velocity and temperature distributions. This project will use those experimental conditions and measurements for validation of CFD simulations.
3) Reynolds number calculations confirmed the flows are fully turbulent, validating the use of turbulence models. The CFD model setup and boundary conditions aimed to replicate the previous experimental conditions for validation purposes.
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
Study on Thermal and Hydrodynamic Indexes of a Nanofluid Flow in a Micro Heat...A Behzadmehr
The paper numerically presents laminar forced convection of a nanofluid flowing in a duct at microscale.
Results were compared with both analytical and experimental data and observed good concordance with
previous studies available in the literature. Influences of Brinkman and Reynolds number on thermal and
hydrodynamic indexes have been investigated. For a given nanofluid, no change in efficiency (heat dissipation
to pumping power) was observed with an increasing in Reynolds number. It was shown that the pressure was
decrease with an increase in Brinkman number. Dependency of Nu increment changes with substrate material.
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
This document compares the design of a shell and tube heat exchanger with baffles using four different methods: 1) Kern's theoretical method, 2) ASPEN simulation software, 3) HTRI simulation software, and 4) SOLIDWORKS simulation software. The same input parameters were used to design a shell and tube heat exchanger with single segmental baffles in each method. The results from all four methods for shell side pressure drop and heat transfer coefficient were found to be in close agreement. The theoretical Kern method design results closely matched the simulation software results, showing proven theoretical methods can accurately model shell and tube heat exchanger performance.
Experimental analysis of heat transfer enhancementin circulariaemedu
This document summarizes an experimental study on enhancing heat transfer in a circular double tube heat exchanger using rectangular inserts. Air was passed through the inner tube while hot water flowed through the outer tube. Heat transfer coefficients and friction factors were determined for the plain tube and with inserts. The results showed that heat transfer was enhanced by 0.9 to 1.9 times with the inserts due to flow disruption, while friction factors increased by 1 to 1.7 times. Heat transfer coefficients increased with Reynolds number whereas friction factors decreased. Validation experiments on a plain tube agreed well with theoretical predictions within 10% uncertainty.
1) The document discusses CFD studies conducted to analyze heat transfer in boiler tubes with different helical rifled geometries.
2) Temperature distributions within plain and rifled tubes were modeled and compared, showing that rifled tubes achieved higher temperatures than plain tubes. Triangular rifled geometry performed best, raising water temperature from 300K to 412K.
3) Rifled geometries enhance heat transfer through inducing turbulence in flow, increasing heat transfer surface area and allowing more uniform heating within the tubes. Proper tube geometry selection can significantly improve boiler performance.
Numerical Analysis of Heat Transfer Enhancement in Pipe-inPipe Helical Coiled...iosrjce
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow). The results show that overall heat transfer coefficients increase with increasing inner Dean number and mass flow rates. Heat transfer rates also increase with higher inner mass flow rates. Counter flow configuration provides better heat transfer than parallel flow. Increasing the inner tube size decreases the total heat transfer rate due to a reduction in annulus cross-sectional area. Measured inner Nusselt numbers agree reasonably well with existing correlations.
Porous media has two specifications: First its dissipation area is greater than the conventional fins that enhance heat convection. Second the irregular motion of the fluid flow around the individual beads mixes the fluid more effectively. Nanofluids are mixtures of base fluid with a very small amount of nanoparticles having dimensions from 1 to 100 nm, with very high thermal conductivities, so it would be the best convection heat transfer by using porous media and nanofluids. Thus studies need to be conducted involving nanofluids in porous media. For that, the purpose of this article is to summarize the published subjects respect to the enhancement of convective heat transfer using porous media and nanofluids and identifies opportunities for future research.
Effect OfProbe Parameters for Determination of Soil Water Content by Using Ti...IJMERJOURNAL
ABSTRACT: The application of Time Domain Reflectometry (TDR) in measuring soil water content is faster, reliable and non-destructive. Rapid increment of soil water content results in sudden reduction of soil shear strength, which will cause detrimental effect to the geotechnical structure. TDR uses two parallel probes to measure the resistance of a porous medium in which directly related to the volumetric water content, θv. Several factors affecting the accuracy of soil water determination such as probe diameter and spacing. It is also noted that the probes material are potentially will affect the results due to electrical resistance of respective materials. This paper presents the effect of probe parameters such as material (i.e. copper, aluminium, steel), diameter and spacing of probe to the accuracy of soil water content reading using TDR.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
JIMEC Thermal modeling and Simulation of HX Conference PaperAhmed Sohail Izhar
1) The document describes a thermal modeling and simulation of an industrial shell and tube heat exchanger used to cool raw natural gas.
2) A thermal model was developed using the effectiveness-NTU method to determine the required heat transfer area and estimate the tube-side and shell-side heat transfer coefficients.
3) The results of the model showed that a heat transfer area of about 1132 m2 is required to provide a thermal duty of 1.4 MW, with tube-side and shell-side heat transfer coefficients of 950 W/m2K and 495 W/m2K respectively.
This document summarizes an experimental study on heat transfer enhancement from surface roughness at laminar flow. Specifically, it examines using circular and oval dimples on an aluminum plate to increase heat transfer from the plate to air flowing over it at Reynolds numbers from 600 to 2000. The study finds that both circular and oval dimples enhance heat transfer compared to a flat plate, while maintaining equivalent or lower pressure drops. The experimental results are validated by comparing the measured Nusselt numbers to theoretical values for a plain vertical plate under laminar flow conditions. In general, the dimpled surfaces increase thermal performance without significantly increasing pressure drops compared to a smooth surface.
The document describes a computational fluid dynamics (CFD) analysis comparing the heat transfer performance of air-cooled heat exchangers using inner-grooved copper tubes with diameters of 12.7mm and 9.52mm. The CFD results show higher heat transfer coefficients and more uniform temperature distribution with the smaller 9.52mm tube. Using the smaller tube in the same design requires 15.2% less copper material.
An experimental study on the airlift packed column with adjustable heightIAEME Publication
This document presents an experimental study on an airlift packed column with adjustable height and multiple air injection points. The study aims to improve liquid flow rate and total head of the system. Experiments were conducted by varying submersion ratio, air flow rate, and number of air injection nozzles. Results show that liquid flow rate increases with higher submersion ratio, air flow rate, and number of nozzles. Using multiple nozzles distributed along the column maintains both high liquid flow rate due to increased gas holdup and total head. The system offers applications in heat and mass transfer operations with adjustable packed bed height and efficient liquid distribution.
This document summarizes a study analyzing electronic chip microchannels using ANSYS software. It presents the background on microchannel cooling technology and prior research. It then describes the numerical model setup in ANSYS, including the microchannel geometry, governing equations, and boundary/flow conditions. Results are shown for temperature contours, velocity vectors, pressure drops, and heat transfer coefficients for different materials and pressure drops. The study found that outlet water temperature was highest for a pressure drop of 30 kPa and when the substrate was silicon. Overall, the document analyzes heat transfer in a microchannel heat sink using computational fluid dynamics software.
Numerical Investigation of Heat Transfer from Two Different Cylinders in Tand...IJERA Editor
A two dimensional technique has been studied numerically to predict the heat transfer from two different cylinders
in tandem arrangement (one is circular and the other is elliptical) using finite element technique with RNG k-ε turbulent
model, taking into consideration the effect of gap ratio (L/Deq ) and Reynolds number , where the distance between
the centers of cylinders is L (L=30 mm and 37 mm), the equivalent diameter of cylinder is Deq=22.5mm and
the range of Reynolds number is 2x103
< Reeq < 21x103 .The commercial CFD software FLUENT was used to get
the thermofluid characteristics (temperature, velocity, kinetic energy and pressure contours ,coefficient of friction ,
heat transfer coefficient , Stanton number …… etc) of the flow around cylinders. The dependency of the heat transfer
coefficient, Stanton number (Sta), pressure drop, and friction factor for circular and elliptical cylinders on the gap
ratio is clear from the results. Results show that, for circular cross section, the heat transfer coefficient is increased as
velocity, and gap ratio increase. On the other hand Sta decreased as velocity increase. The pressure drop and hence
the friction factor increase for circular cylinder as gap ratio increases. For elliptical tube the heat transfer and Sta are
relatively equal to that for circular one at the same gap ratio, but the overall power consumption and friction factor
for elliptical tube is lower than that of circular one. As the elliptical cylinder fixed on the second position the heat
transfer and Sta
increase, on the other hand the pressure drop and hence the friction factor decreases. For all studied
arrangements the highest heat transfer is observed for the arrangement of circular-first and elliptical-second cylinder
and the minimum pressure drop and hence the friction factor are for the elliptical one
Investigation of the Effect of Nanoparticles Mean Diameter on Turbulent Mixed...A Behzadmehr
Abstract
Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase
mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.
On the equality of electric power fractal dimension and capillary pressure fr...Khalid Al-Khidir
On the equality of electric power fractal dimension and capillary pressure fractal dimension for characterizing shajara reservoirs of the permo carboniferous shajara formation
IRJET- Study of Jet Impingement Heat TransferIRJET Journal
This document reviews research on jet impingement heat transfer. It discusses the flow and heat transfer characteristics of single and multiple impinging jets. Key factors that influence heat transfer are jet Reynolds number, nozzle-to-plate spacing, jet pattern, and crossflow. The document summarizes various empirical correlations that have been developed to predict average heat transfer coefficients. It also reviews numerical studies on modeling heat transfer for multi-jet systems and discusses the effects of parameters like Reynolds number, nozzle spacing, crossflow, and jet interference.
Heat Transfer Enhancement Using Aluminium Oxide Nanofluid: Effect of the Base...CSCJournals
The flow and heat transfer is an important phenomenon in engineering systems due to its wide application in electronic cooling, heat exchangers, double pane windows etc.. The enhancement of heat transfer in these systems is an essential topic from an energy saving perspective. The lower heat transfer performance when conventional fluids, such as water, engine oil and ethylene glycol are used hinders improvements in performance and a consequent reduction in the size of such systems. The use of solid particles as an additive suspended into the base fluid is a technique for heat transfer enhancement. Therefore, the heat transfer enhancement in a horizontal circular tube that is maintained at a constant temperature under laminar regime has been investigated numerically. A computational code applied to the problem by use of the finite volume method was developed. Nanofluid was made by dispersion of Al2O3 nanoparticles in pur water and ethylene glycol. Results illustrate that the suspended nanoparticles increase the heat transfer with an increase in the nanoparticles volume fraction and for a considered range of Reynolds numbers. And in other hand, the heat transfer is very sensitive to the base fluid.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
New Microsoft Office PowerPoint PresentationSudhir Shinde
This document summarizes a seminar presentation on heat transfer via jet impingement. The presentation discusses how jet impingement is used to effectively remove large amounts of heat from surfaces, such as in cooling turbine blades and electronics. It reviews factors that influence heat transfer, including nozzle diameter, jet-to-surface spacing, and Reynolds number. The experimental setup examines heat transfer characteristics of air and water jets impinging on a heated surface. Results show that lower jet diameters and spacings and higher Reynolds numbers increase heat transfer. The conclusion is that jet impingement is effective for cooling applications due to the high heat transfer coefficients that can be achieved.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document describes a numerical model for simulating two-dimensional heat and moisture transfer during drying of a rectangular object. The model is based on finite difference solutions of the governing heat and mass transfer equations. Boundary conditions representing convective heat and moisture transfer are applied. Grid independence tests and stability analyses are performed to validate the numerical method. Predicted temperature and moisture distributions from the model are found to agree well with experimental data.
The document presents a new bridgeless single-phase AC-DC converter based on a single-ended primary inductance converter (SEPIC) topology. The proposed rectifier utilizes a bidirectional switch and two fast diodes. It has less conduction losses compared to existing power factor correction rectifiers due to fewer components conducting during each switching cycle. Experimental results show the converter can achieve a high power factor under universal input voltage conditions and provide regulated output voltage for resistive and incandescent lamp loads. Future work may include further optimizing the design for applications requiring high power quality input power.
This document discusses techniques to reduce leakage current and power consumption in static random-access memory (SRAM) cells implemented using independent gate fin field-effect transistors (FinFETs). It first describes the independent gate FinFET SRAM cell design and its advantages over other designs. It then examines two circuit-level leakage reduction techniques: 1) using multi-threshold voltages by connecting high-threshold transistors to reduce leakage when in standby mode, and 2) adding a gated power supply transistor to reduce leakage through stacking effects. Simulation results show that both techniques can reduce leakage current and power in the independent gate FinFET SRAM cell, with multi-threshold voltages providing better leakage control.
This document summarizes the performance enhancement and characterization of a junctionless vertical slit field effect transistor (JLVeSFET). Key findings from simulations include:
1) The JLVeSFET shows an optimized subthreshold slope of 65mV/decade and OFF current of ~10-18A/μm for a 50nm radius device with a high-k dielectric.
2) Using a high-k dielectric (Si3N4) instead of SiO2 increases the Ion/Ioff ratio to ~1011 and reduces the subthreshold slope to 63mV/decade.
3) Increasing the gate doping concentration reduces the subthreshold slope slightly while increasing the Ion/
The document presents a new ontology matching system based on a multi-agent architecture. The system takes ontologies described in XML, RDF Schema, and OWL as input. It uses multiple matchers and filtering to generate mappings between ontology entities. The mappings are then validated. The system is implemented as a multi-agent system with different agent types responsible for resources, matching, generating mappings, and filtering/validating mappings. The architecture allows for robust, flexible, and scalable ontology matching.
This document discusses various techniques for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It describes common PAPR reduction techniques such as partial transmit sequence (PTS), selective mapping (SLM), tone injection, peak cancellation, and peak windowing. It analyzes these techniques based on parameters like distortion, power increase, data rate loss, and bit error rate improvement. The document concludes that while SLM is better for PAPR reduction as it does not cause out-of-band radiation or degrade bit error rate performance, it has the drawback of increased complexity with larger number of subcarriers or phase sequences.
Porous media has two specifications: First its dissipation area is greater than the conventional fins that enhance heat convection. Second the irregular motion of the fluid flow around the individual beads mixes the fluid more effectively. Nanofluids are mixtures of base fluid with a very small amount of nanoparticles having dimensions from 1 to 100 nm, with very high thermal conductivities, so it would be the best convection heat transfer by using porous media and nanofluids. Thus studies need to be conducted involving nanofluids in porous media. For that, the purpose of this article is to summarize the published subjects respect to the enhancement of convective heat transfer using porous media and nanofluids and identifies opportunities for future research.
Effect OfProbe Parameters for Determination of Soil Water Content by Using Ti...IJMERJOURNAL
ABSTRACT: The application of Time Domain Reflectometry (TDR) in measuring soil water content is faster, reliable and non-destructive. Rapid increment of soil water content results in sudden reduction of soil shear strength, which will cause detrimental effect to the geotechnical structure. TDR uses two parallel probes to measure the resistance of a porous medium in which directly related to the volumetric water content, θv. Several factors affecting the accuracy of soil water determination such as probe diameter and spacing. It is also noted that the probes material are potentially will affect the results due to electrical resistance of respective materials. This paper presents the effect of probe parameters such as material (i.e. copper, aluminium, steel), diameter and spacing of probe to the accuracy of soil water content reading using TDR.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
JIMEC Thermal modeling and Simulation of HX Conference PaperAhmed Sohail Izhar
1) The document describes a thermal modeling and simulation of an industrial shell and tube heat exchanger used to cool raw natural gas.
2) A thermal model was developed using the effectiveness-NTU method to determine the required heat transfer area and estimate the tube-side and shell-side heat transfer coefficients.
3) The results of the model showed that a heat transfer area of about 1132 m2 is required to provide a thermal duty of 1.4 MW, with tube-side and shell-side heat transfer coefficients of 950 W/m2K and 495 W/m2K respectively.
This document summarizes an experimental study on heat transfer enhancement from surface roughness at laminar flow. Specifically, it examines using circular and oval dimples on an aluminum plate to increase heat transfer from the plate to air flowing over it at Reynolds numbers from 600 to 2000. The study finds that both circular and oval dimples enhance heat transfer compared to a flat plate, while maintaining equivalent or lower pressure drops. The experimental results are validated by comparing the measured Nusselt numbers to theoretical values for a plain vertical plate under laminar flow conditions. In general, the dimpled surfaces increase thermal performance without significantly increasing pressure drops compared to a smooth surface.
The document describes a computational fluid dynamics (CFD) analysis comparing the heat transfer performance of air-cooled heat exchangers using inner-grooved copper tubes with diameters of 12.7mm and 9.52mm. The CFD results show higher heat transfer coefficients and more uniform temperature distribution with the smaller 9.52mm tube. Using the smaller tube in the same design requires 15.2% less copper material.
An experimental study on the airlift packed column with adjustable heightIAEME Publication
This document presents an experimental study on an airlift packed column with adjustable height and multiple air injection points. The study aims to improve liquid flow rate and total head of the system. Experiments were conducted by varying submersion ratio, air flow rate, and number of air injection nozzles. Results show that liquid flow rate increases with higher submersion ratio, air flow rate, and number of nozzles. Using multiple nozzles distributed along the column maintains both high liquid flow rate due to increased gas holdup and total head. The system offers applications in heat and mass transfer operations with adjustable packed bed height and efficient liquid distribution.
This document summarizes a study analyzing electronic chip microchannels using ANSYS software. It presents the background on microchannel cooling technology and prior research. It then describes the numerical model setup in ANSYS, including the microchannel geometry, governing equations, and boundary/flow conditions. Results are shown for temperature contours, velocity vectors, pressure drops, and heat transfer coefficients for different materials and pressure drops. The study found that outlet water temperature was highest for a pressure drop of 30 kPa and when the substrate was silicon. Overall, the document analyzes heat transfer in a microchannel heat sink using computational fluid dynamics software.
Numerical Investigation of Heat Transfer from Two Different Cylinders in Tand...IJERA Editor
A two dimensional technique has been studied numerically to predict the heat transfer from two different cylinders
in tandem arrangement (one is circular and the other is elliptical) using finite element technique with RNG k-ε turbulent
model, taking into consideration the effect of gap ratio (L/Deq ) and Reynolds number , where the distance between
the centers of cylinders is L (L=30 mm and 37 mm), the equivalent diameter of cylinder is Deq=22.5mm and
the range of Reynolds number is 2x103
< Reeq < 21x103 .The commercial CFD software FLUENT was used to get
the thermofluid characteristics (temperature, velocity, kinetic energy and pressure contours ,coefficient of friction ,
heat transfer coefficient , Stanton number …… etc) of the flow around cylinders. The dependency of the heat transfer
coefficient, Stanton number (Sta), pressure drop, and friction factor for circular and elliptical cylinders on the gap
ratio is clear from the results. Results show that, for circular cross section, the heat transfer coefficient is increased as
velocity, and gap ratio increase. On the other hand Sta decreased as velocity increase. The pressure drop and hence
the friction factor increase for circular cylinder as gap ratio increases. For elliptical tube the heat transfer and Sta are
relatively equal to that for circular one at the same gap ratio, but the overall power consumption and friction factor
for elliptical tube is lower than that of circular one. As the elliptical cylinder fixed on the second position the heat
transfer and Sta
increase, on the other hand the pressure drop and hence the friction factor decreases. For all studied
arrangements the highest heat transfer is observed for the arrangement of circular-first and elliptical-second cylinder
and the minimum pressure drop and hence the friction factor are for the elliptical one
Investigation of the Effect of Nanoparticles Mean Diameter on Turbulent Mixed...A Behzadmehr
Abstract
Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase
mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.
On the equality of electric power fractal dimension and capillary pressure fr...Khalid Al-Khidir
On the equality of electric power fractal dimension and capillary pressure fractal dimension for characterizing shajara reservoirs of the permo carboniferous shajara formation
IRJET- Study of Jet Impingement Heat TransferIRJET Journal
This document reviews research on jet impingement heat transfer. It discusses the flow and heat transfer characteristics of single and multiple impinging jets. Key factors that influence heat transfer are jet Reynolds number, nozzle-to-plate spacing, jet pattern, and crossflow. The document summarizes various empirical correlations that have been developed to predict average heat transfer coefficients. It also reviews numerical studies on modeling heat transfer for multi-jet systems and discusses the effects of parameters like Reynolds number, nozzle spacing, crossflow, and jet interference.
Heat Transfer Enhancement Using Aluminium Oxide Nanofluid: Effect of the Base...CSCJournals
The flow and heat transfer is an important phenomenon in engineering systems due to its wide application in electronic cooling, heat exchangers, double pane windows etc.. The enhancement of heat transfer in these systems is an essential topic from an energy saving perspective. The lower heat transfer performance when conventional fluids, such as water, engine oil and ethylene glycol are used hinders improvements in performance and a consequent reduction in the size of such systems. The use of solid particles as an additive suspended into the base fluid is a technique for heat transfer enhancement. Therefore, the heat transfer enhancement in a horizontal circular tube that is maintained at a constant temperature under laminar regime has been investigated numerically. A computational code applied to the problem by use of the finite volume method was developed. Nanofluid was made by dispersion of Al2O3 nanoparticles in pur water and ethylene glycol. Results illustrate that the suspended nanoparticles increase the heat transfer with an increase in the nanoparticles volume fraction and for a considered range of Reynolds numbers. And in other hand, the heat transfer is very sensitive to the base fluid.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
New Microsoft Office PowerPoint PresentationSudhir Shinde
This document summarizes a seminar presentation on heat transfer via jet impingement. The presentation discusses how jet impingement is used to effectively remove large amounts of heat from surfaces, such as in cooling turbine blades and electronics. It reviews factors that influence heat transfer, including nozzle diameter, jet-to-surface spacing, and Reynolds number. The experimental setup examines heat transfer characteristics of air and water jets impinging on a heated surface. Results show that lower jet diameters and spacings and higher Reynolds numbers increase heat transfer. The conclusion is that jet impingement is effective for cooling applications due to the high heat transfer coefficients that can be achieved.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
This document describes a numerical model for simulating two-dimensional heat and moisture transfer during drying of a rectangular object. The model is based on finite difference solutions of the governing heat and mass transfer equations. Boundary conditions representing convective heat and moisture transfer are applied. Grid independence tests and stability analyses are performed to validate the numerical method. Predicted temperature and moisture distributions from the model are found to agree well with experimental data.
The document presents a new bridgeless single-phase AC-DC converter based on a single-ended primary inductance converter (SEPIC) topology. The proposed rectifier utilizes a bidirectional switch and two fast diodes. It has less conduction losses compared to existing power factor correction rectifiers due to fewer components conducting during each switching cycle. Experimental results show the converter can achieve a high power factor under universal input voltage conditions and provide regulated output voltage for resistive and incandescent lamp loads. Future work may include further optimizing the design for applications requiring high power quality input power.
This document discusses techniques to reduce leakage current and power consumption in static random-access memory (SRAM) cells implemented using independent gate fin field-effect transistors (FinFETs). It first describes the independent gate FinFET SRAM cell design and its advantages over other designs. It then examines two circuit-level leakage reduction techniques: 1) using multi-threshold voltages by connecting high-threshold transistors to reduce leakage when in standby mode, and 2) adding a gated power supply transistor to reduce leakage through stacking effects. Simulation results show that both techniques can reduce leakage current and power in the independent gate FinFET SRAM cell, with multi-threshold voltages providing better leakage control.
This document summarizes the performance enhancement and characterization of a junctionless vertical slit field effect transistor (JLVeSFET). Key findings from simulations include:
1) The JLVeSFET shows an optimized subthreshold slope of 65mV/decade and OFF current of ~10-18A/μm for a 50nm radius device with a high-k dielectric.
2) Using a high-k dielectric (Si3N4) instead of SiO2 increases the Ion/Ioff ratio to ~1011 and reduces the subthreshold slope to 63mV/decade.
3) Increasing the gate doping concentration reduces the subthreshold slope slightly while increasing the Ion/
The document presents a new ontology matching system based on a multi-agent architecture. The system takes ontologies described in XML, RDF Schema, and OWL as input. It uses multiple matchers and filtering to generate mappings between ontology entities. The mappings are then validated. The system is implemented as a multi-agent system with different agent types responsible for resources, matching, generating mappings, and filtering/validating mappings. The architecture allows for robust, flexible, and scalable ontology matching.
This document discusses various techniques for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It describes common PAPR reduction techniques such as partial transmit sequence (PTS), selective mapping (SLM), tone injection, peak cancellation, and peak windowing. It analyzes these techniques based on parameters like distortion, power increase, data rate loss, and bit error rate improvement. The document concludes that while SLM is better for PAPR reduction as it does not cause out-of-band radiation or degrade bit error rate performance, it has the drawback of increased complexity with larger number of subcarriers or phase sequences.
This document summarizes research that analyzed the effect of temperature on the parameters of silicon solar cells. It was found that the open circuit voltage (Voc) of the solar cells decreases linearly as temperature increases from 20°C to 80°C. In contrast, the short circuit current (Isc) was found to increase only slightly with higher temperatures. The maximum efficiency of 18.5% was obtained at 20°C when Voc was 667.3mV and Isc was 37.56mA. Overall, the study demonstrated that higher temperatures negatively impact the Voc, fill factor, and efficiency of silicon solar cells.
ME 6302 manufacturing technology 1notes with question paperGopinath Guru
This document describes the manufacturing technology course ME6302 for the second year mechanical engineering students. It covers the following topics:
1. Metal casting processes including sand casting, pattern materials, melting furnaces, and special casting processes like shell molding and investment casting.
2. Metal joining processes focusing on various welding techniques like gas welding, arc welding, and special processes like laser beam and electron beam welding.
3. Metal forming processes such as rolling, forging, extrusion, and sheet metal processes including bending and stretching.
4. Manufacture of plastic components using molding techniques like injection molding and blow molding.
5. It provides the course content split into 5 units,
This document presents a numerical investigation of mixed convective flow inside straight and bend pipes. The study examines the effects of inlet Rayleigh number and Reynolds number on velocity and temperature profiles within the pipes. For a straight horizontal pipe, secondary flow develops at higher L/D ratios due to density variations, producing maximum velocity at the bottom. For bend pipes, secondary flow in the horizontal section combines with buoyancy effects in the vertical section. Higher Rayleigh numbers indicate a transition from forced to mixed to free convection. Results show secondary flow weakens and profiles become more uniform at farther downstream positions.
Numerical Investigation of Mixed Convective Flow inside a Straight Pipe and B...iosrjce
The present study deals with a numerical investigation of steady laminar and turbulent mixed
convection heat transfer in a horizontal pipe and bend pipe using air as the working fluid.The thermal boundary
condition chosen is that of uniform temperature at the outer wall. Computations were performed to investigate
the effect of inlet Rayleigh number and Reynolds number in the velocity and temperature profile at inside of the
pipe. The secondary flow is more intense in the upper part of the cross-section. It increases throughout the
cross-section until its intensity reaches a maximum, and then it becomes weak at far downstream. For the
horizontal pipe the value of the L/D ratio becomes more than 10 the secondary flow effects are neutralized and
the velocity profile almost become constant throughout.
This document presents a numerical investigation of mixed convective flow inside straight and bend pipes. The study examines the effects of inlet Rayleigh number and Reynolds number on velocity and temperature profiles within the pipes. For a straight horizontal pipe, secondary flow develops at higher L/D ratios, producing maximum velocity at the bottom of the pipe. As L/D increases beyond 10, secondary flow effects diminish. Higher Rayleigh numbers indicate stronger buoyancy effects on flow and temperature distribution. In a bend pipe, secondary flow and buoyancy-driven effects combine to influence mixed convection patterns.
Thermal analysis of various duct cross sections using altair hyperworks softwaresushil Choudhary
In this work thermal analysis and comparison of various duct cross sections is done computationally using Altair
Hyperworks Software. Simple Analytical results were obtained for conduction and convection through the ducts
which can be used to build up thermal circuit. The inner surface of all ducts is maintained at constant
temperature and ambient air is at certain temperature that is less than inner surface temperature of pipe. Due to
temperature difference heat will flow from higher temperature to lower temperature. Due to temperature
difference heat will flow from higher temperature to lower temperature. The material of pipe provides
conductive resistance and air provides convective resistance. Hence this is a mix mode of heat transfer. The heat
transfer takes place in one dimension only and properties are considered to be isotropic. The ducts are assumed
to be made of aluminium having known thermal conductivity and density. The surroundings of ducts have
known convective heat transfer coefficient and temperature. The results are obtained on hyperview which are for
heat flux, temperature gradient and grid temperature. The different characteristics can be obtained by varying the
material of the ducts.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document describes an experimental study of heat transfer in a rectangular duct with and without internal V-shaped ribs. Experiments were conducted with air flow in turbulent regime (Reynolds numbers 3000-18000) in smooth duct and ducts with continuous or discrete internal V-shaped ribs. Temperature and pressure measurements were taken to determine heat transfer coefficients and friction factors for different configurations. Results showed that continuous ribs enhanced heat transfer more than discrete ribs, but also increased pressure drop more substantially. Heat transfer enhancement was dependent on rib geometry and position.
A Review on Comparison between Shell And Tube Heat Exchanger And Helical Coil...ijiert bestjournal
The curved shape of the tube causes the flowing fluid to experience centrifugal force. The
extent of centrifugal force experienced depends on the local axial velocity of the fluid particle
and radius of curvature of the coil. The fluid particles flowing at the core of the pipe have
higher velocities than those flowing near to the pipe wall. Thus the fluid particles flowing
close to the tube wall experience a lower centrifugal force than the fluid particles flowing in
the tube core. This causes the fluid from the core region to be pushed towards the outer wall.
This stream bifurcates at the wall and drives the fluid towards the inner wall along the tube
periphery, causing generation of counter-rotating vortices called secondary flows which
produce additional transport of the fluid over the cross section of the pipe. This additional
convective transport increases heat transfer and the pressure drop when compared to that in a
straight tube.
Study on Effect of Twisted Tape Insert Geometry in Heat Exchangerijtsrd
The heat exchanger is a device used to transfer heat from hot fluid to cold fluid. The current research reviews existing work conducted in improving performance of heat exchanger by varying geometric profile, baffling space, baffling inclination and use of helical inserts. The existing researches were conducted using both experimental and numerical techniques. The effect of operational parameters on performance of heat exchanger is also presented. Deepak Bhoi | Sudhir Singh Rajput "Study on Effect of Twisted Tape Insert Geometry in Heat Exchanger" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-2 , February 2022, URL: https://www.ijtsrd.com/papers/ijtsrd49163.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/49163/study-on-effect-of-twisted-tape-insert-geometry-in-heat-exchanger/deepak-bhoi
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. A computational fluid dynamics (CFD) analysis was conducted to determine the effect of varying parameters like inner tube diameter, mass flow rates, and flow configuration (parallel vs. counter flow) on heat transfer characteristics. The CFD results showed that decreasing the inner tube diameter and increasing the mass flow rates led to higher overall heat transfer coefficients. Counter flow configuration provided better heat transfer than parallel flow. Validation of the CFD model showed decent agreement with existing empirical correlations for heat transfer in helical coils.
This document presents a numerical analysis of heat transfer enhancement in pipe-in-pipe helical coiled heat exchangers. Computational fluid dynamics (CFD) was used to analyze the effect of varying parameters like inner tube diameter, mass flow rates, and coil configuration on heat transfer characteristics. The results show that overall heat transfer coefficient increases with increasing inner Dean number and decreasing inner tube diameter. Counter-flow configuration provides better heat transfer than parallel flow. Validation of CFD results was done using existing Nusselt number correlations from literature. Increasing tube size or annulus mass flow rate decreases the total heat transfer rate.
Pressure and Heat Transfer over a Series of In-line Non-Circular Ducts in a P...Carnegie Mellon University
Flow and heat transfer for two-dimensional laminar flow at low Reynolds number for five in-line ducts of various cross-sections in a parallel plate channel are studied in this paper. The governing equations were solved using finite-volume method. A commercial CFD software, ANSYS Fluent 14.5 was used to solve this problem. A total of three different non-conventional cross-sections and their characteristics are compared with that of circular cross-section. Shape-1, Shape-2 and Shape-3 performed better for heat transfer rate than the circular cross-section, but also offered higher resistance to the flow. Shape-1 offered less resistance to flow at Re < 200 but post Re = 200 the resistance equalled to that of the Shape-3. In overall, Shape-2 performed better when the heat transfer and resistance to flow were considered.
Pressure and heat transfer over a series of in line non-circular ducts in a p...Carnegie Mellon University
This document summarizes a study on pressure and heat transfer over a series of five inline non-circular ducts of various cross-sections within a parallel plate channel. The governing equations for laminar, steady-state flow were solved using finite volume methods in ANSYS Fluent. Three non-circular duct shapes (Shape-1, Shape-2, Shape-3) were compared against a circular duct baseline. Shape-1, Shape-2 and Shape-3 showed higher heat transfer rates but also higher flow resistance compared to the circular duct. Shape-2 performed best when considering both heat transfer and pressure drop. Streamlines, velocity profiles, normalized pressure drop, and Nusselt numbers were analyzed over a Reynolds number
IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mechanical and civil engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mechanical and civil engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
technoloTwo dimensional numerical simulation of the combined heat transfer in...ijmech
A numerical investigation was conducted to analyze the flow field and heat transfer characteristics in a vertical channel withradiation and blowing from the wall. Hydrodynamic behaviour and heat transfer results are obtained by the solution of the complete Navier–Stokesand energy equations using a control volume finite element method. Turbulent flow with "Low Reynolds Spalart-Allmaras Turbulence Model" and radiation with "Discrete Transfer Radiation Method" had been modeled. In order to have a complete survey, this article has a wide range of study in different domains including velocity profiles at different locations, turbulent viscosity, shear stress, suctioned mass flow rate in different magnitude of the input
Rayleigh number, blowing Reynoldsnumber, radiation parameter, Prandtl number, the ratio of length to width and also ratio of opening thickness to width of the channel. In addition, effects of variation in any of the above non-dimensional numbers on parameters of the flow are clearly illustrated. At the end resultants had been compared with experimental data which demonstrated that in the present study, results have a great accuracy, relative errors are very small and the curve portraits are in a great
agreement with real experiments.
NUMERICAL SIMULATION OF FORCED CONVECTION HEAT TRANSFER ENHANCEMENT BY POROUS...IAEME Publication
Pin fins have a variety of applications in industry due to their excellent heat transfer performance, e.g., in cooling of electronic components, in cooling of gas turbine blades, and
recently, in hot water boilers of central heating systems. The forced convective heat transfer in three dimensional porous pin fin channels is numerically studied using ANSYS Fluent. Geometric modelling is done using Design Modeller and CFD Meshing is carried out using ANSYS Meshing Preprocessor. The effects of Reynolds number (Re), pore density (PPI) and pin fin form are studied in detail.
This document summarizes a study on improving heat transfer in tubes by using different types of twisted tape inserts. Experiments were conducted to assess heat transfer and pressure drop in a tube fitted with alternating clockwise and counter-clockwise twisted tapes (C-CC tapes) as well as serrated twisted tapes (STT). For C-CC tapes, heat transfer increased with higher twist ratios and lower twist angles. For STT, heat transfer increased with higher serration depth ratios but decreased with higher serration width ratios. Thermal performance factors above unity indicated STT provided advantages over plain tubes or twisted tapes. Correlations for Nusselt number and friction factor were determined for both C-CC and STT.
Helically Coiled Tube with Different Geometry and Curvature Ratio on Convecti...AM Publications
A helically coil-tube heat exchanger is generally applied in industry applications due to its compact structure, larger heat transfer area and higher heat transfer capability. Several studies from literature have also indicated that heat transfer rate in helically coiled tube are superior to straight tube due to complex flow pattern exist inside helical pipe. The concept behind compact heat exchanger is to decrease size and increase heat load which is the typical feature of modern helical tube heat exchanger. While the heat transfer characteristics of helical coil heat exchangers are available in the literature, This paper elaborates a brief review on different curvature ratio and geometry of tubes in heat transfer through heat exchangers.
NATURAL CONVECTION HEAT TRANSFER IN INCLINED OPEN ANNULUS PASSEGE HEATED FROM...IAEME Publication
Natural convection is investigated experimentally in an open cylindrical annulus heated with both annulus inner and outer sides under same constant heat flux condition to study the effect of angle of inclination and heat flux on heat transfer. Heat transfer results are given for inclination angles of 0o
(horizontal), 30o , 60o and 90o (vertical) using annulus diameter ratio of 1.8, inner and outer tube length 50 cm and heat flux from 70 W/m2 to 600W/m2 . The results show that the local and average Nusselt number increase as the heat flux increase and when angle of inclination changed from 0o
(horizontal) to 90o (vertical).An empirical correlations of average Nusselt number as a function of Rayleigh number were deduced.
This document summarizes a study on the thermal analysis of circular inclined pipes subjected to natural convection using computational fluid dynamics (CFD). The study investigated the effect of parameters like tube diameter, heat supplied, and tube inclination on the temperature and heat transfer coefficient through experimental testing and CFD analysis. The experimental results were validated against CFD results, with less than 5% error found between the two. It was found that temperature increased with increasing pipe diameter and heat supply. The temperature was also strongly influenced by heat flux and diameter, and weakly dependent on tube inclination.
Numerical Simulation of a Tube in Tube Helical Coiled Heat Exchanger using CFDCarnegie Mellon University
Heat exchangers are used widely in industrial application such as chemical,
food processing, power production, refrigeration and air-conditioning
industries. Helical coiled heat exchangers are used in order to obtain a large
heat transfer per unit volume and to enhance the heat transfer rate on the inside
surface. In the present study, CFD simulations are carried out for a counter
flow tube in tube helical heat exchanger where hot water flows through the
inner tube and cold water flows through the outer tube. From the simulation
results heat transfer coefficient, pressure drop and nusselt number are
calculated. The heat transfer characteristics of the same are compared with that
of a counter flow tube in tube straight tube heat exchanger of same length
under same temperature and flow conditions. CFD simulation results showed
that the helical tube in tube heat exchanger is more effective than the straight
tube in tube heat exchanger.
This document summarizes a survey on string similarity matching search techniques. It discusses how string similarity matching is used to find relevant information in text collections. The document reviews different algorithms for string matching, including edit distance, NR-grep, n-grams, and approaches based on hashing and locality-sensitive hashing. It analyzes techniques like pattern matching, threshold-based joins, and vector representations. The goal is to present an overview of the field and compare algorithm performance for similarity searches.
The document reviews various methods for enhancing the bandwidth of microstrip patch antennas. It discusses how modifying the patch shape, using multilayer configurations, planar/stacked multi-resonator structures, and different feeding techniques can increase the antenna's bandwidth. Modified patch shapes, multilayer structures, and proximity coupled feeding provide the greatest bandwidth enhancements, with multilayer designs potentially achieving over 70% bandwidth. The review concludes that slot loading and multilayer techniques are most effective for enhancing bandwidth while maintaining a small antenna size.
This document presents a new method for interpolation called weighted average interpolation (WAI). WAI uses the concepts of positive and negative effect to determine the influence of neighboring data points. Correction factors are derived from Pascal's triangle to match the results of WAI to Lagrange interpolation. The method is extended to extrapolation and unevenly spaced data using similar concepts. WAI aims to reduce the number of operations compared to Lagrange interpolation while maintaining accuracy.
This document presents a theorem about the almost Norlund summability of conjugate Fourier series. It generalizes previous results by Pati (1961) and Singh and Singh (1993). The main theorem states that if the conjugate partial sums of a Fourier series satisfy certain conditions, including being bounded by a function that approaches 0 as n approaches infinity, then the conjugate Fourier series is almost Norlund summable to the integral of the function at every point where the integral exists. The proof utilizes lemmas about the behavior of the conjugate partial sums and applies mean value theorems to show the necessary conditions are met. References to previous related works are also provided.
The document discusses the determination of diffusion constants in boronated powder metallurgy samples of the iron-carbon-copper system. Experiments were conducted on powdered samples with 0.1% carbon and 1-3% copper. The thickness of the boride layers formed after boronation at temperatures of 920-980°C were measured. The data was used to calculate the activation energy (Q) and pre-exponential factor (Do) based on parabolic growth curves. The results show that Q increases with sample density from 5.8 to 7 g/cm3. Adding up to 2% copper reduces Q values, but higher copper concentrations increase Q similar to pure iron samples.
This document compares various biometric methods for identification and verification. It discusses fingerprint recognition, face recognition, voice recognition, and iris recognition as some of the main biometric techniques. For each method, it describes how the biometric data is captured and analyzed, the advantages and disadvantages, and examples of applications where the technique can be used. The document provides an overview of the history of biometrics and the typical modules involved in a biometric system, such as sensors, feature extraction, matching, and template databases.
This document describes the design of a digital phase locked loop (PLL) with a divide by 4/5 prescaler. The digital PLL uses a digital phase frequency detector, time to digital converter, thermometric decoder, and digitally controlled oscillator. The proposed PLL design uses an accumulator type DCO and ring oscillator type TDC to achieve fast lock time and reduced jitter. The final system incorporates all the components to function as a digital PLL that locks when the reference and feedback frequencies match.
The document discusses energy efficient routing protocols for clustered wireless sensor networks. It provides an overview of wireless sensor networks and discusses how clustering is commonly used to improve energy efficiency and scalability. The document reviews several existing clustering-based routing protocols and analyzes their approaches for prolonging network lifetime by minimizing energy consumption in wireless sensor networks.
The document discusses bit error rate (BER) performance analysis of M-ary quadrature amplitude modulation (M-QAM) for implementation of orthogonal frequency-division multiplexing (OFDM). It analyzes the theoretical BER of M-QAM under different modulation orders and signal-to-noise ratios (SNR). The analysis shows that higher order M-QAM has higher BER than lower order M-QAM for the same SNR due to decreased symbol distances as the modulation order increases. It also discusses the use of M-QAM modulation in OFDM systems and outlines challenges in implementing higher order M-QAM for OFDM.
This document analyzes the groundwater quality of South Karaikal and Nagapattinam districts in Tamil Nadu, India. 14 groundwater samples were collected and analyzed for physicochemical parameters including major ions. Spatial variation maps were generated for parameters like calcium, chloride, sodium, and bicarbonate which showed high and low concentration regions. Piper and Durov plots indicated mixed temporary and permanent water hardness. Sodium absorption ratio values identified areas of excellent, good and fair water quality for irrigation. Overall, comparison to standards showed groundwater was not suitable for drinking in most areas.
The document discusses security issues in distributed database systems. It begins by defining distributed databases and their architecture. It then discusses three main security aspects: access control, authentication, and encryption. The document also discusses distributed database system design considerations like concurrency control and data fragmentation. Emerging security tools for distributed databases mentioned include data warehousing, data mining, collaborative computing, distributed object systems, and web applications. Maintaining security when building and querying data warehouses from multiple sources is highlighted as a key challenge.
This document discusses techniques for classifying sentiments and mining opinions from text data. It begins with defining key terminology in opinion mining like opinion feature, sentiment, polarity, holder and time. It then discusses various data sources for opinion mining like blogs, reviews sites, datasets, microblogs and other text. It describes the granularity of opinion mining tasks at the document level, sentence level and feature level. Finally, it outlines approaches to opinion mining including supervised learning techniques like Naive Bayes, SVM and unsupervised learning techniques that use lexical resources without prior training. Evaluation metrics for sentiment classification systems like accuracy, precision, recall and F1 measure are also discussed.
This document describes a study that uses Kohonen neural network (KNN) to automatically identify the cutoff frequency for denoising electrocardiogram (ECG) signals. The methodology involves collecting noisy ECG data, removing baseline wandering using empirical mode decomposition, transforming the signal to the frequency domain using fast Fourier transform, applying KNN to cluster the frequency coefficients and identify the cutoff frequency, and filtering the signal using a finite impulse response low pass filter with the identified cutoff frequency. The results show that the KNN approach more effectively denoises the ECG signals compared to conventional filtering methods by identifying a lower cutoff frequency that removes more noise.
This document describes a study that developed a generic transliteration tool to transliterate words from English to Hindi for cross-lingual information access applications. It discusses the challenges of transliteration from English to Hindi due to differences in phonetic properties between the two languages. The study then evaluates the performance of four existing transliteration editor tools - Xlit, GIST, Google Transliteration, and Microsoft Hindi writing tool - on test data including English words, human names, and other terms. Test results show variations in the transliterated output for the same input across the different tools.
This document discusses reliable data communication over mobile ad hoc networks using the WEAC protocol with ARQ technique. It first describes the WEAC protocol and mobile ad hoc network architecture. It then discusses different ARQ techniques like Stop-and-Wait, Go-Back-N, and Selective Repeat. Go-Back-N protocol is analyzed in more detail. The document also discusses ARQ feedback types and presents simulation results on uplink throughput with and without errors and ARQ. It concludes that ARQ can improve network throughput over mobile ad hoc networks by reducing dropped packets at relay nodes.
The document presents a conceptual framework for Library 2.0 services. It discusses various web 2.0 tools like blogs, wikis, RSS feeds, podcasts, and their potential applications for library services. A conceptual framework is proposed with four main components: 1) web 2.0 technologies to be used, 2) objectives of Library 2.0 services, 3) maintenance and updating of services, and 4) evaluation and feedback mechanisms. Examples are given of how different tools can be applied, such as using blogs for new book announcements and wikis for subject guides.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.