An experimental investigation of heat transfer and
friction factor of a smooth tube fitted with full length twisted
tape inserts for laminar flow have been studied under uniform
wall heat flux condition. The experiments has been carried
out to study the tape fin effect by using full length tape inserts
of different materials namely Aluminum, Stainless steel and
insulated tape. The tapes have twist ratios from 5.2 to 3.4. It is
found that, for the flow in smooth tubes, full length twisted
tapes yield improvement in average Nusselt number, for
Reynolds number range of 200 to 2000.For Aluminum tapes,
the maximum improvement in Nusselt number range from
50% to 100%; for Stainless steel tapes, maximum
improvement in Nusselt number range from 40% to 94% and
for insulated tapes, maximum improvement in Nusselt
number range from 40% to 67%. The isothermal friction factor
for the flow with the twisted tape inserts are 340% to 750 %
higher as compared with those of smooth tube flow, in the
given range of twist ratios.
The heat transfer and friction factor were
experimentally investigated in a louvered strip inserted tube in
turbulent flow region. A copper tube of (I.D=28mm, O.D=32mm)
and 900mm length was used. A louvered strip insert with
different geometrical configuration was inserted into the smooth
tube. A uniform heat flux condition was created by wrapping
heating tape of 2500 watt around the test section. Fibre glass
cloth was used as a thermal insulator which surrounds the
heating tape. Outer surface temperature of the tube were
measured at five different equally spaced points of test section by
k-typethermocouples. Two thermocouples were used to measure
the inlet and outlet temperature of water. The Reynolds numbers
were varied in the range of 2500 to 4000 with constant heat flux
of 24 kw/m2 for smooth tube and louvered strip inserted. Nusselt
number and friction factor obtained for louvered strip (with
forward backward arrangement) > Nusselt number and friction
factor for louvered strip (with semi-forward semi-backward
arrangement)> Nusselt number and friction factor for louvered
strip (with forward arrengement).
Enhancement of heat transfer in tube in-tube heat exchangers using twisted in...Ijrdt Journal
Heat exchangers have several industrial and engineering applications. There are different methods to enhance heat transfer in heat exchangers. Passive technique of heat transfer is the most economical and best suited one. The role of inserts in internal forced convection has been widely acknowledged as a passive device in the heat transfer enhancement. One of such technique is introduction of twisted inserts which enhances the heat transfer coefficient. Twisted aluminium inserts when placed in the path of the fluid flow, creates a high degree of turbulence resulting in an increase in the heat transfer rate. By placing inserts, it is expected that the benefits due to the increased heat transfer coefficient overcome the higher cost involved because of the increased frictional losses. The work mainly focuses on increasing the heat transfer of tube-in-tube heat exchangers by using twisted aluminium inserts. The results obtained from the tube with twisted aluminium insert are compared with those without twisted insert using standard properties of heat transfer (LMTD & Effectiveness). The relations based on the data gathered during this work for predicting the heat transfer coefficient of the horizontal pipe with twisted taped insert are proposed. According to the results, in order to obtain maximum heat transfer, the twist ratio must be at the lowest level.
ENHANCEMENT OF HEAT TRANSFER IN SHELL AND TUBE HEAT EXCHANGER WITH TABULATOR ...IAEME Publication
The present work reported the use of variant twisted tapes fitted in a double pipe heat exchanger to improve the fluid mixing that leads to higher heat transfer rate with respect to that of the plain-twisted tape. Heat transfer, flow friction and thermal enhancement factor characteristics in a double pipe heat exchanger fitted with plain and variant twisted tapes using water as working fluid are investigated experimentally. Tests are performed for laminar flow ranges. The experimental data for a plain tube and plain-twisted tapes are validated using the standard correlations available in the literature. Two different variant twisted tapes which include V cut-twisted tape and Horizontal wing cut-twisted tape with twist ratios of y = 2.0, 4.4 and 6.0 are used. In addition, the variation of heat transfer coefficient of copper–nanofluids with different of Reynold's number and volume concentration of nanoparticles in plain tube without twisted tape.
Enhancing heat transfer surface are used in many
engineering applications such as heat exchanger, air conditioning,
chemical reactor and refrigeration systems, hence many
techniques have been investigated on enhancement of heat
transfer rate and decrease the size and cost of the involving
equipment especially in heat exchangers. One of the most
important techniques used are passive heat transfer technique.
These tchniques when adopted in Heat exchanger proved that the
overall thermal performance improved significantly. This paper
reviews experimental and numerical works taken by researchers
on this technique since 2004 such as twisted tape, wire coil, swirl
flow generator, etc. to enhance the thermal efficiency in heat
exchangers and useful to designers implementing passive
augmentation techniques in heat exchange. The authors found
that variously developed twisted tape inserts are popular
researched and used to strengthen the heat transfer efficiency for
heat exchangers. The other techniques used for specific work
environments are studied in this paper. Twisted tape inserts
perform better in laminar flow than turbulent flow. However, the
other several passive techniques such as ribs, conical nozzle, and
conical ring, etc. are generally more efficient in the turbulent flow
than in the laminar flow.
Heat transfer enhancement and friction factor analysis in tube using conical ...eSAT Journals
Abstract Role of the conical spring array for the heat transfer enhancement and pressure drop change in a pipe with constant heat flux boundary condition was investigated. Three different arrangements of conical spring array inserts were used in the experimental setup. Conical spring inserts with diverging conical spring, converging-diverging conical spring and converging conical spring array inserts arrangements were used. Water was used as a working fluid in the experimental setup. It was found that use of conical spring array inserts arrangement leads to enhancement in heat transfer. Higher heat transfer rate was achieved in the divergent spring array arrangement than the converging-diverging and converging arrangement. However, maximum friction factor is achieved in the diverging spring array insert arrangement. By increasing the Reynolds Number for different turbulator arrangement, the significant increase in Nusselt number was obtained. The enhancement in Nusselt Number for the diverging, converging-diverging, converging conical spring array arrangement was 645% ,431% and 259% respectively. The heat transfer enhancement efficiency can be evaluated based on the power consumption per unit mass of fluid. Heat transfer enhancement efficiencies were found for the divergent spring array arrangement up to 277% and for the convergent-divergent spring arrangement up to 212% and for the convergent spring array arrangement up to 153%. Keywords— Heat exchanger, Heat transfer enhancement, Friction factor, Conical spring turbulator, Heat transfer enhancement efficiency
The heat transfer and friction factor were
experimentally investigated in a louvered strip inserted tube in
turbulent flow region. A copper tube of (I.D=28mm, O.D=32mm)
and 900mm length was used. A louvered strip insert with
different geometrical configuration was inserted into the smooth
tube. A uniform heat flux condition was created by wrapping
heating tape of 2500 watt around the test section. Fibre glass
cloth was used as a thermal insulator which surrounds the
heating tape. Outer surface temperature of the tube were
measured at five different equally spaced points of test section by
k-typethermocouples. Two thermocouples were used to measure
the inlet and outlet temperature of water. The Reynolds numbers
were varied in the range of 2500 to 4000 with constant heat flux
of 24 kw/m2 for smooth tube and louvered strip inserted. Nusselt
number and friction factor obtained for louvered strip (with
forward backward arrangement) > Nusselt number and friction
factor for louvered strip (with semi-forward semi-backward
arrangement)> Nusselt number and friction factor for louvered
strip (with forward arrengement).
Enhancement of heat transfer in tube in-tube heat exchangers using twisted in...Ijrdt Journal
Heat exchangers have several industrial and engineering applications. There are different methods to enhance heat transfer in heat exchangers. Passive technique of heat transfer is the most economical and best suited one. The role of inserts in internal forced convection has been widely acknowledged as a passive device in the heat transfer enhancement. One of such technique is introduction of twisted inserts which enhances the heat transfer coefficient. Twisted aluminium inserts when placed in the path of the fluid flow, creates a high degree of turbulence resulting in an increase in the heat transfer rate. By placing inserts, it is expected that the benefits due to the increased heat transfer coefficient overcome the higher cost involved because of the increased frictional losses. The work mainly focuses on increasing the heat transfer of tube-in-tube heat exchangers by using twisted aluminium inserts. The results obtained from the tube with twisted aluminium insert are compared with those without twisted insert using standard properties of heat transfer (LMTD & Effectiveness). The relations based on the data gathered during this work for predicting the heat transfer coefficient of the horizontal pipe with twisted taped insert are proposed. According to the results, in order to obtain maximum heat transfer, the twist ratio must be at the lowest level.
ENHANCEMENT OF HEAT TRANSFER IN SHELL AND TUBE HEAT EXCHANGER WITH TABULATOR ...IAEME Publication
The present work reported the use of variant twisted tapes fitted in a double pipe heat exchanger to improve the fluid mixing that leads to higher heat transfer rate with respect to that of the plain-twisted tape. Heat transfer, flow friction and thermal enhancement factor characteristics in a double pipe heat exchanger fitted with plain and variant twisted tapes using water as working fluid are investigated experimentally. Tests are performed for laminar flow ranges. The experimental data for a plain tube and plain-twisted tapes are validated using the standard correlations available in the literature. Two different variant twisted tapes which include V cut-twisted tape and Horizontal wing cut-twisted tape with twist ratios of y = 2.0, 4.4 and 6.0 are used. In addition, the variation of heat transfer coefficient of copper–nanofluids with different of Reynold's number and volume concentration of nanoparticles in plain tube without twisted tape.
Enhancing heat transfer surface are used in many
engineering applications such as heat exchanger, air conditioning,
chemical reactor and refrigeration systems, hence many
techniques have been investigated on enhancement of heat
transfer rate and decrease the size and cost of the involving
equipment especially in heat exchangers. One of the most
important techniques used are passive heat transfer technique.
These tchniques when adopted in Heat exchanger proved that the
overall thermal performance improved significantly. This paper
reviews experimental and numerical works taken by researchers
on this technique since 2004 such as twisted tape, wire coil, swirl
flow generator, etc. to enhance the thermal efficiency in heat
exchangers and useful to designers implementing passive
augmentation techniques in heat exchange. The authors found
that variously developed twisted tape inserts are popular
researched and used to strengthen the heat transfer efficiency for
heat exchangers. The other techniques used for specific work
environments are studied in this paper. Twisted tape inserts
perform better in laminar flow than turbulent flow. However, the
other several passive techniques such as ribs, conical nozzle, and
conical ring, etc. are generally more efficient in the turbulent flow
than in the laminar flow.
Heat transfer enhancement and friction factor analysis in tube using conical ...eSAT Journals
Abstract Role of the conical spring array for the heat transfer enhancement and pressure drop change in a pipe with constant heat flux boundary condition was investigated. Three different arrangements of conical spring array inserts were used in the experimental setup. Conical spring inserts with diverging conical spring, converging-diverging conical spring and converging conical spring array inserts arrangements were used. Water was used as a working fluid in the experimental setup. It was found that use of conical spring array inserts arrangement leads to enhancement in heat transfer. Higher heat transfer rate was achieved in the divergent spring array arrangement than the converging-diverging and converging arrangement. However, maximum friction factor is achieved in the diverging spring array insert arrangement. By increasing the Reynolds Number for different turbulator arrangement, the significant increase in Nusselt number was obtained. The enhancement in Nusselt Number for the diverging, converging-diverging, converging conical spring array arrangement was 645% ,431% and 259% respectively. The heat transfer enhancement efficiency can be evaluated based on the power consumption per unit mass of fluid. Heat transfer enhancement efficiencies were found for the divergent spring array arrangement up to 277% and for the convergent-divergent spring arrangement up to 212% and for the convergent spring array arrangement up to 153%. Keywords— Heat exchanger, Heat transfer enhancement, Friction factor, Conical spring turbulator, Heat transfer enhancement efficiency
An experimental study of heat transfer in plane circular tube fitted with the V-Shaped Aluminum
turbulators is performed for plane circular tube. The objective of this Project work is to analyses heat transfer
coefficient and friction characteristics in a plane circular tube fitted with the V-Shaped Aluminum turbulators.
The experimentations are firstly carried out on the plane circular pipe and heat transfer augmentation were
recorded and then the v-shaped Aluminum turbulators are fitted in the same plane pipe and then again the heat
transfer augmentation is recorded and then both of them is compared. Experimental investigations have been
carried out to study the effects of the V-Shaped Aluminum turbulators on heat transfer, friction and
enhancement efficiency, in a circular tube. We used the V-Shaped aluminum turbulators with the turbulator
element length of 200mm, 160mm and 120mm.We found the heat transfer argumentation.The mean heat
transfer rates obtained from using the V-Aluminum turbulators are 198%, 213% and 241% for turbulator
element Length of 200mm, 160mm and 120 mm respectively. All of the experiments are carried out at the
same inlet conditions with the Reynolds number, based on the tube diameter (Re), in a range of 3000 to
10000
EXPERIMENTAL STUDY ON THE ANALYSIS OF HEAT ENHANCEMENT IN CORRUGATED TWISTED ...P singh
In heat exchanger, the enthalpy is transferred between two or more fluids, at different temperatures. The major challenge in designing a heat exchanger is to make the equipment more compact and achieve a high heat transfer rate using minimum pumping power. In recent years, the high cost of energy and material has resulted in an increased effort aimed at producing more efficient heat exchange equipment. Furthermore, as a heat exchanger becomes older, the resistance to heat transfer increases owing to fouling or scaling. The heat transfer rate can be improved by introducing a disturbance in the fluid flow thereby breaking the viscous and thermal boundary layer. However, in the process pumping power may increase significantly and ultimately the pumping cost becomes high. Therefore, to achieve a desired heat transfer rate in an existing heat exchanger at an economic pumping power, several techniques have been proposed in recent years and are discussed under the classification section.
In this work, a study of transient heat transfer in double tube heat exchanger has enhanced. The inner tube of the setup was made with corrugation on both inner and outer walls by twisting the pipe from one end, which gives the more swirling motion to the fluid particles flowing over it. The flow inside the pipe was considered as turbulent, and the analysis was done experimentally and theoretically by using the ANSYS workbench. The experimental results were compared with the experimental values taken in the setup done by considering the inner tube as normal pipe. In both heat exchangers the values were taken and compared with the theoretical analysis. Temperature distribution and heat transfer rate were calculated and the details of the study have been discussed in this paper.
Experimental Study of Heat Transfer Enhancement of Pipe-inPipe Helical Coil H...iosrjce
Heat transfer enhancement in pipe in pipe helical coils has been research by many researchers.
While the many literatures available on heat transfer characteristics of helical coil heat exchangers. There is
very few published on validate experimental results through Computational Fluid Dynamics. This paper focuses
on experimental investigation of fluid-to-fluid heat transfer enhancement of pipe-in-pipe helical coil tubes. The
methodology of experimental analysis of a helical tubes heat exchanger, the effect of the inside tubes at constant
value of mass flow rate in Dean Number and also established the surface heat transfer coefficient. Heat transfer
characteristics inside pipe-in-pipe helical coils for various boundary conditions, that the specification of a
constant temperature at hot water inlet, constant mass flow rate. Hence, the pipe-in-pipe heat exchanger is
considering different mass flow rate inside and annulus. The fabrication of experimental setup is estimate the
heat transfer enhancement in inside helical coil tubes
CFD Analysis of Concentric Tube Heat Exchanger Using Twisted TapesIJARIIT
In this paper, the three dimensional CFD modeling studies on heat transfer, friction factor and thermal performance
of concentric tube heat exchanger using twisted tapes (Plain, V-cut, , Jagged V-cut) with different twist ratios (y=2.0, 4.0) are
used. Twisted tapes are used to augment the heat transfer by creating turbulence in the fluid flow. Various methods are applied
to increase thermal performance of heat transfer devices such as treated surfaces, rough surfaces, swirling flow devices, coiled
tubes, and surface tension devices. Out of these twisted tape method is used to increase the thermal performance. Twisted tape
inserts on effectiveness of heat exchanger has analyzed for different Reynolds Number. The maximum thermal performance
factor was obtained by the Jagged V-cut twisted tape (H=50) insert compare to other twisted tapes. Simultaneously the friction
factor has been analyzed
Review on Comparative Study between Helical Coil and Straight Tube Heat Excha...IOSR Journals
The purpose of this study is to determine the relative advantage of using a helically coiled heat
exchanger against a straight tube heat exchanger. It is found that the heat transfer in helical circular tubes is
higher as compared to Straight tube due to their shape. Helical coils offer advantageous over straight tubes due
to their compactness and increased heat transfer coefficient. The increased heat transfer coefficients are a
consequence of the curvature of the coil, which induces centrifugal forces to act on the moving fluid, resulting in
the development of secondary flow. The curvature of the coil governs the centrifugal force while the pitch (or
helix angle) influences the torsion to which the fluid is subjected to. The centrifugal force results in the
development of secondary flow. Due to the curvature effect, the fluid streams in the outer side of the pipe moves
faster than the fluid streams in the inner side of the pipe. The difference in velocity sets-in secondary flows,
whose pattern changes with the Dean number of the flow.
In current work the fluid to fluid heat exchange is taken into consideration, Most of the investigations on heat transfer coefficients are for constant wall temperature or constant heat flux. The effectiveness, overall
heat transfer coefficient, effect of coldwater flow rate on effectiveness of heat exchanger when hot water mass
flow rate is kept constant and effect of hot water flow rate on effectiveness when cold water flow rate kept
constant studied and compared for parallel flow, counter flow arrangement of Helical coil and Straight tube
heat exchangers. The inner heat transfer coefficient calculated from Wilson plot method. Then Nusselt no and
correlation obtained on the basis of inner heat transfer coefficient. All readings were taken at steady state
condition of heat exchanger.
The result shows that the heat transfer coefficient is affected by the geometry of the heat exchanger.
Helical coil heat exchanger are superior in all aspect studied here.
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.
Analysis of Coiled-Tube Heat Exchangers to Improve Heat Transfer Rate With Sp...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
Esign and thermal evaluation of shell and helical coil heat exchangereSAT Journals
Abstract
Heat exchangers are the important engineering equipments used for transferring heat from one fluid to another. Heat exchangers are widely used in various kinds of application such as power plants, nuclear reactors, refrigeration and air-conditioning systems, heat recovery systems, petrochemical, mechanical, biomedical industries. Helical coil heat exchangers are gaining wide importance now-a-days because it can give high heat transfer coefficient in small footprint of surface area. This paper focuses on the designing of shell and helical coil heat exchanger and its thermal evaluation with counter flow configuration. The thermal analysis is carried out considering the various parameters such as flow rate of cold water, flow rate of hot water, temperature, effectiveness and overall heat transfer coefficient.
Keywords— Helical coil heat exchanger, Counter flow, Flow rate, effectiveness, heat transfer coefficient etc.
EXPERIMENTATION ON COPPER TUBE WITH INTERNAL THREADING FOR A HEAT EXCHANGER P...Journal For Research
Experimental model has been carried out to study the effect of heat transfer, thermal enhancement factor and friction factor in a smooth copper tube and different test copper tube having internal threads of pitch ( p=3.5mm), with water as a working fluid media. For such experimentation purpose Reynolds number were varied in the range of 4000 to 8000. The copper tube (OD=38mm, ID=25mm, t=6.5mm) was subjected to constant and uniform heat flux. The experimental data obtained from test tube having different surface geometry i.e. by internal threading of different pitch (p=3.5mm) were compared with smooth circular copper tube. The effect of different surface geometry of inside copper tube i.e. by threading with varying pitch on thermal enhancement factor, heat transfer and friction factor were presented. In that experimental we also calculate Nusselt number, Prandtl number, pitch like heat transfer parameter. The heat transfer rate for copper tubes having internal threads was found to be much higher than smooth circular copper tube for a given value Reynolds number. So simply by changing the internal surface geometry the performance of circular section copper tube is improved.
HEAT TRANSFER AUGMENTATION OF LAMINAR NANOFLUID FLOW IN HORIZONTAL TUBE INSER...IAEME Publication
In this paper, an experimental study on the heat transfer enhancement and friction factor characteristics for fully developed laminar CuO/distilled-water (DI-water) nanofluid flow through horizontal tube inserted with different geometries of twisted tapes under constant heat flux condition ranged from 4483 to 10000 W/m^2. φ=0.08% and 0.35% volume concentrations of CuO nanoparticles are suspending in distilled water to prepare nanofluid. Twisted types made from copper material with twist ratios Y=2.6 and 5.3 twist ratios, thickness t=1 and 2mm and with semicircular and triangular cuts shape were used to study their effect on twisted tape performance. Results showed that both convective heat transfer in terms of average Nusselt number (Nu) ̅ and friction factor have significantly increasing with inserting twisted tape with nanofluids as working fluid comparing with nanofluids or DI-water in smooth tube case and this enhancement increases as both Reynold number and volume concentration increases.
An experimental study of heat transfer in plane circular tube fitted with the V-Shaped Aluminum
turbulators is performed for plane circular tube. The objective of this Project work is to analyses heat transfer
coefficient and friction characteristics in a plane circular tube fitted with the V-Shaped Aluminum turbulators.
The experimentations are firstly carried out on the plane circular pipe and heat transfer augmentation were
recorded and then the v-shaped Aluminum turbulators are fitted in the same plane pipe and then again the heat
transfer augmentation is recorded and then both of them is compared. Experimental investigations have been
carried out to study the effects of the V-Shaped Aluminum turbulators on heat transfer, friction and
enhancement efficiency, in a circular tube. We used the V-Shaped aluminum turbulators with the turbulator
element length of 200mm, 160mm and 120mm.We found the heat transfer argumentation.The mean heat
transfer rates obtained from using the V-Aluminum turbulators are 198%, 213% and 241% for turbulator
element Length of 200mm, 160mm and 120 mm respectively. All of the experiments are carried out at the
same inlet conditions with the Reynolds number, based on the tube diameter (Re), in a range of 3000 to
10000
EXPERIMENTAL STUDY ON THE ANALYSIS OF HEAT ENHANCEMENT IN CORRUGATED TWISTED ...P singh
In heat exchanger, the enthalpy is transferred between two or more fluids, at different temperatures. The major challenge in designing a heat exchanger is to make the equipment more compact and achieve a high heat transfer rate using minimum pumping power. In recent years, the high cost of energy and material has resulted in an increased effort aimed at producing more efficient heat exchange equipment. Furthermore, as a heat exchanger becomes older, the resistance to heat transfer increases owing to fouling or scaling. The heat transfer rate can be improved by introducing a disturbance in the fluid flow thereby breaking the viscous and thermal boundary layer. However, in the process pumping power may increase significantly and ultimately the pumping cost becomes high. Therefore, to achieve a desired heat transfer rate in an existing heat exchanger at an economic pumping power, several techniques have been proposed in recent years and are discussed under the classification section.
In this work, a study of transient heat transfer in double tube heat exchanger has enhanced. The inner tube of the setup was made with corrugation on both inner and outer walls by twisting the pipe from one end, which gives the more swirling motion to the fluid particles flowing over it. The flow inside the pipe was considered as turbulent, and the analysis was done experimentally and theoretically by using the ANSYS workbench. The experimental results were compared with the experimental values taken in the setup done by considering the inner tube as normal pipe. In both heat exchangers the values were taken and compared with the theoretical analysis. Temperature distribution and heat transfer rate were calculated and the details of the study have been discussed in this paper.
Experimental Study of Heat Transfer Enhancement of Pipe-inPipe Helical Coil H...iosrjce
Heat transfer enhancement in pipe in pipe helical coils has been research by many researchers.
While the many literatures available on heat transfer characteristics of helical coil heat exchangers. There is
very few published on validate experimental results through Computational Fluid Dynamics. This paper focuses
on experimental investigation of fluid-to-fluid heat transfer enhancement of pipe-in-pipe helical coil tubes. The
methodology of experimental analysis of a helical tubes heat exchanger, the effect of the inside tubes at constant
value of mass flow rate in Dean Number and also established the surface heat transfer coefficient. Heat transfer
characteristics inside pipe-in-pipe helical coils for various boundary conditions, that the specification of a
constant temperature at hot water inlet, constant mass flow rate. Hence, the pipe-in-pipe heat exchanger is
considering different mass flow rate inside and annulus. The fabrication of experimental setup is estimate the
heat transfer enhancement in inside helical coil tubes
CFD Analysis of Concentric Tube Heat Exchanger Using Twisted TapesIJARIIT
In this paper, the three dimensional CFD modeling studies on heat transfer, friction factor and thermal performance
of concentric tube heat exchanger using twisted tapes (Plain, V-cut, , Jagged V-cut) with different twist ratios (y=2.0, 4.0) are
used. Twisted tapes are used to augment the heat transfer by creating turbulence in the fluid flow. Various methods are applied
to increase thermal performance of heat transfer devices such as treated surfaces, rough surfaces, swirling flow devices, coiled
tubes, and surface tension devices. Out of these twisted tape method is used to increase the thermal performance. Twisted tape
inserts on effectiveness of heat exchanger has analyzed for different Reynolds Number. The maximum thermal performance
factor was obtained by the Jagged V-cut twisted tape (H=50) insert compare to other twisted tapes. Simultaneously the friction
factor has been analyzed
Review on Comparative Study between Helical Coil and Straight Tube Heat Excha...IOSR Journals
The purpose of this study is to determine the relative advantage of using a helically coiled heat
exchanger against a straight tube heat exchanger. It is found that the heat transfer in helical circular tubes is
higher as compared to Straight tube due to their shape. Helical coils offer advantageous over straight tubes due
to their compactness and increased heat transfer coefficient. The increased heat transfer coefficients are a
consequence of the curvature of the coil, which induces centrifugal forces to act on the moving fluid, resulting in
the development of secondary flow. The curvature of the coil governs the centrifugal force while the pitch (or
helix angle) influences the torsion to which the fluid is subjected to. The centrifugal force results in the
development of secondary flow. Due to the curvature effect, the fluid streams in the outer side of the pipe moves
faster than the fluid streams in the inner side of the pipe. The difference in velocity sets-in secondary flows,
whose pattern changes with the Dean number of the flow.
In current work the fluid to fluid heat exchange is taken into consideration, Most of the investigations on heat transfer coefficients are for constant wall temperature or constant heat flux. The effectiveness, overall
heat transfer coefficient, effect of coldwater flow rate on effectiveness of heat exchanger when hot water mass
flow rate is kept constant and effect of hot water flow rate on effectiveness when cold water flow rate kept
constant studied and compared for parallel flow, counter flow arrangement of Helical coil and Straight tube
heat exchangers. The inner heat transfer coefficient calculated from Wilson plot method. Then Nusselt no and
correlation obtained on the basis of inner heat transfer coefficient. All readings were taken at steady state
condition of heat exchanger.
The result shows that the heat transfer coefficient is affected by the geometry of the heat exchanger.
Helical coil heat exchanger are superior in all aspect studied here.
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.
Analysis of Coiled-Tube Heat Exchangers to Improve Heat Transfer Rate With Sp...IJMER
Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formula and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80–100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10–600% larger compared to the common helically coiled heat exchangers. New empirical Co-relation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration.
Esign and thermal evaluation of shell and helical coil heat exchangereSAT Journals
Abstract
Heat exchangers are the important engineering equipments used for transferring heat from one fluid to another. Heat exchangers are widely used in various kinds of application such as power plants, nuclear reactors, refrigeration and air-conditioning systems, heat recovery systems, petrochemical, mechanical, biomedical industries. Helical coil heat exchangers are gaining wide importance now-a-days because it can give high heat transfer coefficient in small footprint of surface area. This paper focuses on the designing of shell and helical coil heat exchanger and its thermal evaluation with counter flow configuration. The thermal analysis is carried out considering the various parameters such as flow rate of cold water, flow rate of hot water, temperature, effectiveness and overall heat transfer coefficient.
Keywords— Helical coil heat exchanger, Counter flow, Flow rate, effectiveness, heat transfer coefficient etc.
EXPERIMENTATION ON COPPER TUBE WITH INTERNAL THREADING FOR A HEAT EXCHANGER P...Journal For Research
Experimental model has been carried out to study the effect of heat transfer, thermal enhancement factor and friction factor in a smooth copper tube and different test copper tube having internal threads of pitch ( p=3.5mm), with water as a working fluid media. For such experimentation purpose Reynolds number were varied in the range of 4000 to 8000. The copper tube (OD=38mm, ID=25mm, t=6.5mm) was subjected to constant and uniform heat flux. The experimental data obtained from test tube having different surface geometry i.e. by internal threading of different pitch (p=3.5mm) were compared with smooth circular copper tube. The effect of different surface geometry of inside copper tube i.e. by threading with varying pitch on thermal enhancement factor, heat transfer and friction factor were presented. In that experimental we also calculate Nusselt number, Prandtl number, pitch like heat transfer parameter. The heat transfer rate for copper tubes having internal threads was found to be much higher than smooth circular copper tube for a given value Reynolds number. So simply by changing the internal surface geometry the performance of circular section copper tube is improved.
HEAT TRANSFER AUGMENTATION OF LAMINAR NANOFLUID FLOW IN HORIZONTAL TUBE INSER...IAEME Publication
In this paper, an experimental study on the heat transfer enhancement and friction factor characteristics for fully developed laminar CuO/distilled-water (DI-water) nanofluid flow through horizontal tube inserted with different geometries of twisted tapes under constant heat flux condition ranged from 4483 to 10000 W/m^2. φ=0.08% and 0.35% volume concentrations of CuO nanoparticles are suspending in distilled water to prepare nanofluid. Twisted types made from copper material with twist ratios Y=2.6 and 5.3 twist ratios, thickness t=1 and 2mm and with semicircular and triangular cuts shape were used to study their effect on twisted tape performance. Results showed that both convective heat transfer in terms of average Nusselt number (Nu) ̅ and friction factor have significantly increasing with inserting twisted tape with nanofluids as working fluid comparing with nanofluids or DI-water in smooth tube case and this enhancement increases as both Reynold number and volume concentration increases.
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.
Experimental Investigation of Heat Transfer Using “Twisted Aluminium Tape”IJERA Editor
Heat exchanger has a wide industrial and engineering applications. Increasing the efficiency of heat exchanger will increase the overall performance of the unit. This paper is about increasing the heat transfer coefficient of heat exchanger by causing a turbulence in the liquid flow through the pipe. For causing the turbulence, liquid flow is subjected to a Twisted Aluminium Tape (TAT) which will increase the Reynolds number of flow. This will ensure heat transfer through the length of flow and thus there will be an increased heat transfer rate. The increased turbulence and higher shear caused by Twisted Aluminium Tape (TAT) will offer resistance to fouling also. KEY ]
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.
The Effect of insertion of different geometries on heat transfer performance ...IJMER
Abstract: Under turbulent flow conditions, the increase in heat transfer rate is more significant than that under laminar flow conditions. The turbulent effects become a dominant factor over secondary flow at higher Reynolds number. The turbulent flow can be produced by inserting different geometries in the circular pipe. This study focuses on the various methods or geometries used to produce turbulent geometries and its effect on the heat transfer. The turbulent generators with different geometrical
configurations have been used as one of the passive heat transfer enhancement techniques and are the most widely used in tubes in several heat transfer applications. Insertion of such geometries may lead to increase the friction factor and pressure drop which directly enhances the heat transfer characteristics.
Experimental study on heat transfer and friction factor characteristics in la...eSAT Publishing House
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
The Effect of insertion of different geometries on heat transfer performance ...IJMER
Under turbulent flow conditions, the increase in heat transfer rate is more significant than
that under laminar flow conditions. The turbulent effects become a dominant factor over secondary flow
at higher Reynolds number. The turbulent flow can be produced by inserting different geometries in the
circular pipe. This study focuses on the various methods or geometries used to produce turbulent
geometries and its effect on the heat transfer. The turbulent generators with different geometrical
configurations have been used as one of the passive heat transfer enhancement techniques and are the
most widely used in tubes in several heat transfer applications. Insertion of such geometries may lead to
increase the friction factor and pressure drop which directly enhances the heat transfer characteristics.
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.
EXPERIMENTAL INVESTIGATION OF FLOW CONDENSATION HEAT TRANSFER IN RECTANGULAR ...IAEME Publication
Condensation heat transfer coefficients and pressure drops in horizontal rectangular minichannel was measured using the specially designed aluminium test section with hydraulic diameter of 2mm. The data are reported for steam is a
refrigerant and water as a coolant. The experimental investigation was carried out mass flux range of 88.89 kg/m2
s to 177.78 kg/m2 s, vapour quality ranges from 20-80% and a saturation temperature of 100°C.
Enhancement of Heat Transfer and Thermo-Hydraulic Performance Using Triangula...IJERA Editor
Solar heat has been thrust area of research to explore renewable energy utilisation for the past few decades. In
solar air heaters artificial roughness is tried on the surface of the absorber plate by adding small roughness
elements to enhance the heat transfer rate. In the present work triangular protrusion are provided to act as
roughness elements over the surface of the aluminum absorber plate. The experimental study is carried out on
the effect of change in apex angle of protrusions on the heat transfer rate by keeping the other design parameters
unchanged. Maximum heat transfer rate and thermo-hydraulic performance between the range of apex angle 300
and 600 is studied. The Nusselt number is between 50 and 110, friction factor 4.5-6.7x10-3, Stanton number is 6-
14x10-3. The heat transfer rate and thermo-hydraulic performance are observed to be maximum for 450 apex
angle and least for the 600 plate.
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.
Effect of Wavy (Corrugated) Twisted Tape Inserts on Heat Transfer in a double...ijiert bestjournal
In the present work heat transfer and friction factor properties we re experimentally investigated by using copper wavy (corrugated) twisted tape inserts. The turbulent flow w as created by inserting the wavy twisted tape inserts into the inner tube of heat exchanger creating high rate of t urbulence in pipe,which results in increasing heat transfer enhancement and pressure drop. The tape consists of the cor rugations and the twisting with various twist ratios (TR=10.7,8.5,7.1). The length and width of insert was 1 meter an d 14 mm respectively. The outer tube of heat exchanger is made up of mild steel with outside diameter .0198 m & .0142 m inside diameter and the inner tube is made up of copper with .038 m outside diameter and .032 m inside di ameter. The length of pipe in pipe heat exchanger is 1.4 m. The bulk mean temperatures at various posit ions are used for different flow rate of water. From the obtained results the new Correlations for Nusselt number and friction factor are developed for twisted tape inserts. The Reynolds number is varied from 5000 to 17000. The results of varying twists in wavy twisted tape inserts with different pitches have been compared with the val ues for the smooth tube. It showed that the highest heat transfer rate was achieved for the wavy twis ted tape with twist ration 7.1. The Nusselt number value increased by 172 % and friction factor value increased by 32.11% as compared to the sm ooth tube values.
Performance Analysis of Copper Twisted Tape Inserts for Heat Transfer in A Ci...IJERA Editor
Thermal Performance of heat transfer devices can be improved by heat transfer enhancement techniques. In the present study, heat transfer from hot air to cold water by double pipe heat exchanger for plain tube and plain tube with twisted inserts is experimentally investigated at isothermal condition. The twisted tape inserts when placed in the path of the flow of the fluid, create a high degree of turbulence resulting in an increase in the heat transfer rate. By inserting twisted tape with twist ratio y=5 and y=7 in a concentric tube heat exchanger, the Nusselt number increases gradually from 920 to 6700 and it is 12-15 % higher than plain tube. This is due to the generation of secondary flow in the tube (turbulence flow). Also the heat transfer coefficient is 15 % higher than the plain tube due to increase in degree of swirl.
Power System State Estimation - A ReviewIDES Editor
The aim of this article is to provide a comprehensive
survey on power system state estimation techniques. The
algorithms used for finding the system states under both static
and dynamic state estimations are discussed in brief. The
authors are opinion that the scope of pursuing research in the
area of state estimation with PMU and SCADA measurements
is the state of the art and timely.
Artificial Intelligence Technique based Reactive Power Planning Incorporating...IDES Editor
Reactive Power Planning is a major concern in the
operation and control of power systems This paper compares
the effectiveness of Evolutionary Programming (EP) and
New Improved Differential Evolution (NIMDE) to solve
Reactive Power Planning (RPP) problem incorporating
FACTS Controllers like Static VAR Compensator (SVC),
Thyristor Controlled Series Capacitor (TCSC) and Unified
power flow controller (UPFC) considering voltage stability.
With help of Fast Voltage Stability Index (FVSI), the critical
lines and buses are identified to install the FACTS controllers.
The optimal settings of the control variables of the generator
voltages,transformer tap settings and allocation and parameter
settings of the SVC,TCSC,UPFC are considered for reactive
power planning. The test and Validation of the proposed
algorithm are conducted on IEEE 30–bus system and 72-bus
Indian system.Simulation results shows that the UPFC gives
better results than SVC and TCSC and the FACTS controllers
reduce the system losses.
Design and Performance Analysis of Genetic based PID-PSS with SVC in a Multi-...IDES Editor
Damping of power system oscillations with the help
of proposed optimal Proportional Integral Derivative Power
System Stabilizer (PID-PSS) and Static Var Compensator
(SVC)-based controllers are thoroughly investigated in this
paper. This study presents robust tuning of PID-PSS and
SVC-based controllers using Genetic Algorithms (GA) in
multi machine power systems by considering detailed model
of the generators (model 1.1). The effectiveness of FACTSbased
controllers in general and SVC-based controller in
particular depends upon their proper location. Modal
controllability and observability are used to locate SVC–based
controller. The performance of the proposed controllers is
compared with conventional lead-lag power system stabilizer
(CPSS) and demonstrated on 10 machines, 39 bus New England
test system. Simulation studies show that the proposed genetic
based PID-PSS with SVC based controller provides better
performance.
Optimal Placement of DG for Loss Reduction and Voltage Sag Mitigation in Radi...IDES Editor
This paper presents the need to operate the power
system economically and with optimum levels of voltages has
further led to an increase in interest in Distributed
Generation. In order to reduce the power losses and to improve
the voltage in the distribution system, distributed generators
(DGs) are connected to load bus. To reduce the total power
losses in the system, the most important process is to identify
the proper location for fixing and sizing of DGs. It presents a
new methodology using a new population based meta heuristic
approach namely Artificial Bee Colony algorithm(ABC) for
the placement of Distributed Generators(DG) in the radial
distribution systems to reduce the real power losses and to
improve the voltage profile, voltage sag mitigation. The power
loss reduction is important factor for utility companies because
it is directly proportional to the company benefits in a
competitive electricity market, while reaching the better power
quality standards is too important as it has vital effect on
customer orientation. In this paper an ABC algorithm is
developed to gain these goals all together. In order to evaluate
sag mitigation capability of the proposed algorithm, voltage
in voltage sensitive buses is investigated. An existing 20KV
network has been chosen as test network and results are
compared with the proposed method in the radial distribution
system.
Line Losses in the 14-Bus Power System Network using UPFCIDES Editor
Controlling power flow in modern power systems
can be made more flexible by the use of recent developments
in power electronic and computing control technology. The
Unified Power Flow Controller (UPFC) is a Flexible AC
transmission system (FACTS) device that can control all the
three system variables namely line reactance, magnitude and
phase angle difference of voltage across the line. The UPFC
provides a promising means to control power flow in modern
power systems. Essentially the performance depends on proper
control setting achievable through a power flow analysis
program. This paper presents a reliable method to meet the
requirements by developing a Newton-Raphson based load
flow calculation through which control settings of UPFC can
be determined for the pre-specified power flow between the
lines. The proposed method keeps Newton-Raphson Load Flow
(NRLF) algorithm intact and needs (little modification in the
Jacobian matrix). A MATLAB program has been developed to
calculate the control settings of UPFC and the power flow
between the lines after the load flow is converged. Case studies
have been performed on IEEE 5-bus system and 14-bus system
to show that the proposed method is effective. These studies
indicate that the method maintains the basic NRLF properties
such as fast computational speed, high degree of accuracy and
good convergence rate.
Study of Structural Behaviour of Gravity Dam with Various Features of Gallery...IDES Editor
The size and shape of opening in dam causes the
stress concentration, it also causes the stress variation in the
rest of the dam cross section. The gravity method of the analysis
does not consider the size of opening and the elastic property
of dam material. Thus the objective of study is comprises of
the Finite Element Method which considers the size of
opening, elastic property of material, and stress distribution
because of geometric discontinuity in cross section of dam.
Stress concentration inside the dam increases with the opening
in dam which results in the failure of dam. Hence it is
necessary to analyses large opening inside the dam. By making
the percentage area of opening constant and varying size and
shape of opening the analysis is carried out. For this purpose
a section of Koyna Dam is considered. Dam is defined as a
plane strain element in FEM, based on geometry and loading
condition. Thus this available information specified our path
of approach to carry out 2D plane strain analysis. The results
obtained are then compared mutually to get most efficient
way of providing large opening in the gravity dam.
Assessing Uncertainty of Pushover Analysis to Geometric ModelingIDES Editor
Pushover Analysis a popular tool for seismic
performance evaluation of existing and new structures and is
nonlinear Static procedure where in monotonically increasing
loads are applied to the structure till the structure is unable
to resist the further load .During the analysis, whatever the
strength of concrete and steel is adopted for analysis of
structure may not be the same when real structure is
constructed and the pushover analysis results are very sensitive
to material model adopted, geometric model adopted, location
of plastic hinges and in general to procedure followed by the
analyzer. In this paper attempt has been made to assess
uncertainty in pushover analysis results by considering user
defined hinges and frame modeled as bare frame and frame
with slab modeled as rigid diaphragm and results compared
with experimental observations. Uncertain parameters
considered includes the strength of concrete, strength of steel
and cover to the reinforcement which are randomly generated
and incorporated into the analysis. The results are then
compared with experimental observations.
Secure Multi-Party Negotiation: An Analysis for Electronic Payments in Mobile...IDES Editor
This paper is an attempt to base on auctions which
presents a frame work for the secure multi-party decision
protocols. In addition to the implementations which are very
light weighted, the main focus is on synchronizing security
features for avoiding agreements manipulations and reducing
the user traffic. Through this paper one can understand that
this different auction protocols on top of the frame work can
be collaborated using mobile devices. This paper present the
negotiation between auctioneer and the proffered and this
negotiation shows that multiparty security is far better than
the existing system.
Selfish Node Isolation & Incentivation using Progressive ThresholdsIDES Editor
The problems associated with selfish nodes in
MANET are addressed by a collaborative watchdog approach
which reduces the detection time for selfish nodes thereby
improves the performance and accuracy of watchdogs[1]. In
the related works they make use of credit based systems, reputation
based mechanisms, pathrater and watchdog mechanism
to detect such selfish nodes. In this paper we follow an approach
of collaborative watchdog which reduces the detection
time for selfish nodes and also involves the removal of such
selfish nodes based on some progressively assessed thresholds.
The threshold gives the nodes a chance to stop misbehaving
before it is permanently deleted from the network.
The node passes through several isolation processes before it
is permanently removed. Another version of AODV protocol
is used here which allows the simulation of selfish nodes in
NS2 by adding or modifying log files in the protocol.
Various OSI Layer Attacks and Countermeasure to Enhance the Performance of WS...IDES Editor
Wireless sensor networks are networks having non
wired infrastructure and dynamic topology. In OSI model each
layer is prone to various attacks, which halts the performance
of a network .In this paper several attacks on four layers of
OSI model are discussed and security mechanism is described
to prevent attack in network layer i.e wormhole attack. In
Wormhole attack two or more malicious nodes makes a covert
channel which attracts the traffic towards itself by depicting a
low latency link and then start dropping and replaying packets
in the multi-path route. This paper proposes promiscuous mode
method to detect and isolate the malicious node during
wormhole attack by using Ad-hoc on demand distance vector
routing protocol (AODV) with omnidirectional antenna. The
methodology implemented notifies that the nodes which are
not participating in multi-path routing generates an alarm
message during delay and then detects and isolate the
malicious node from network. We also notice that not only
the same kind of attacks but also the same kind of
countermeasures can appear in multiple layer. For example,
misbehavior detection techniques can be applied to almost all
the layers we discussed.
Responsive Parameter based an AntiWorm Approach to Prevent Wormhole Attack in...IDES Editor
The recent advancements in the wireless technology
and their wide-spread deployment have made remarkable
enhancements in efficiency in the corporate and industrial
and Military sectors The increasing popularity and usage of
wireless technology is creating a need for more secure wireless
Ad hoc networks. This paper aims researched and developed
a new protocol that prevents wormhole attacks on a ad hoc
network. A few existing protocols detect wormhole attacks but
they require highly specialized equipment not found on most
wireless devices. This paper aims to develop a defense against
wormhole attacks as an Anti-worm protocol which is based on
responsive parameters, that does not require as a significant
amount of specialized equipment, trick clock synchronization,
no GPS dependencies.
Cloud Security and Data Integrity with Client Accountability FrameworkIDES Editor
The Cloud based services provide much efficient
and seamless ways for data sharing across the cloud. The fact
that the data owners no longer possess data makes it very
difficult to assure data confidentiality and to enable secure
data sharing in the cloud. Despite of all its advantages this
will remain a major limitation that acts as a barrier to the
wider deployment of cloud based services. One of the possible
ways for ensuring trust in this aspect is the introduction of
accountability feature in the cloud computing scenario. The
Cloud framework requires promotion of distributed
accountability for such dynamic environment[1]. In some
works, there‘s an accountable framework suggested to ensure
distributed accountability for data sharing by the generation
of only a log of data access, but without any embedded feedback
mechanism for owner permission towards data
protection[2].The proposed system is an enhanced client
accountability framework which provides an additional client
side verification for each access towards enhanced security of
data. The integrity of content of data which resides in the
cloud service provider is also maintained by secured
outsourcing. Besides, the authentication of JAR(Java Archive)
files are done to ensure file protection and to maintain a safer
environment for data sharing. The analysis of various
functionalities of the framework depicts both the
accountability and security feature in an efficient manner.
Genetic Algorithm based Layered Detection and Defense of HTTP BotnetIDES Editor
A System state in HTTP botnet uses HTTP protocol
for the creation of chain of Botnets thereby compromising
other systems. By using HTTP protocol and port number 80,
attacks can not only be hidden but also pass through the
firewall without being detected. The DPR based detection
leads to better analysis of botnet attacks [3]. However, it
provides only probabilistic detection of the attacker and also
time consuming and error prone. This paper proposes a Genetic
algorithm based layered approach for detecting as well as
preventing botnet attacks. The paper reviews p2p firewall
implementation which forms the basis of filtering.
Performance evaluation is done based on precision, F-value
and probability. Layered approach reduces the computation
and overall time requirement [7]. Genetic algorithm promises
a low false positive rate.
Enhancing Data Storage Security in Cloud Computing Through SteganographyIDES Editor
in cloud computing data storage is a significant issue
because the entire data reside over a set of interconnected
resource pools that enables the data to be accessed through
virtual machines. It moves the application software’s and
databases to the large data centers where the management of
data is actually done. As the resource pools are situated over
various corners of the world, the management of data and
services may not be fully trustworthy. So, there are various
issues that need to be addressed with respect to the
management of data, service of data, privacy of data, security
of data etc. But the privacy and security of data is highly
challenging. To ensure privacy and security of data-at-rest in
cloud computing, we have proposed an effective and a novel
approach to ensure data security in cloud computing by means
of hiding data within images following is the concept of
steganography. The main objective of this paper is to prevent
data access from cloud data storage centers by unauthorized
users. This scheme perfectly stores data at cloud data storage
centers and retrieves data from it when it is needed.
The main tasks of a Wireless Sensor Network
(WSN) are data collection from its nodes and communication
of this data to the base station (BS). The protocols used for
communication among the WSN nodes and between the WSN
and the BS, must consider the resource constraints of nodes,
battery energy, computational capabilities and memory. The
WSN applications involve unattended operation of the network
over an extended period of time. In order to extend the lifetime
of a WSN, efficient routing protocols need to be adopted. The
proposed low power routing protocol based on tree-based
network structure reliably forwards the measured data towards
the BS using TDMA. An energy consumption analysis of the
WSN making use of this protocol is also carried out. It is
found that the network is energy efficient with an average
duty cycle of 0:7% for the WSN nodes. The OmNET++
simulation platform along with MiXiM framework is made
use of.
Permutation of Pixels within the Shares of Visual Cryptography using KBRP for...IDES Editor
The security of authentication of internet based
co-banking services should not be susceptible to high risks.
The passwords are highly vulnerable to virus attacks due to
the lack of high end embedding of security methods. In order
for the passwords to be more secure, people are generally
compelled to select jumbled up character based passwords
which are not only less memorable but are also equally prone
to insecurity. Multiple use of distributed shares has been
studied to solve the problem of authentication by algorithms
based on thresholding of pixels in image processing and visual
cryptography concepts where the subset of shares is considered
for the recovery of the original image for authentication using
correlation function[1][2].The main disadvantage in the above
study is the plain storage of shares and also one of the shares
is being supplied to the customer, which will lead to the
possibility of misuse by a third party. This paper proposes a
technique for scrambling of pixels by key based random
permutation (KBRP) within the shares before the
authentication has been attempted. Total number of shares to
be created is dependent on the multiplicity of ownership of
the account. By this method the problem of uncertainty among
the customers with regard to security, storage, retrieval of
holding of half of the shares is minimized.
This paper presents a trifocal Rotman Lens Design
approach. The effects of focal ratio and element spacing on
the performance of Rotman Lens are described. A three beam
prototype feeding 4 element antenna array working in L-band
has been simulated using RLD v1.7 software. Simulated
results show that the simulated lens has a return loss of –
12.4dB at 1.8GHz. Beam to array port phase error variation
with change in the focal ratio and element spacing has also
been investigated.
Band Clustering for the Lossless Compression of AVIRIS Hyperspectral ImagesIDES Editor
Hyperspectral images can be efficiently compressed
through a linear predictive model, as for example the one
used in the SLSQ algorithm. In this paper we exploit this
predictive model on the AVIRIS images by individuating,
through an off-line approach, a common subset of bands, which
are not spectrally related with any other bands. These bands
are not useful as prediction reference for the SLSQ 3-D
predictive model and we need to encode them via other
prediction strategies which consider only spatial correlation.
We have obtained this subset by clustering the AVIRIS bands
via the clustering by compression approach. The main result
of this paper is the list of the bands, not related with the
others, for AVIRIS images. The clustering trees obtained for
AVIRIS and the relationship among bands they depict is also
an interesting starting point for future research.
Microelectronic Circuit Analogous to Hydrogen Bonding Network in Active Site ...IDES Editor
A microelectronic circuit of block-elements
functionally analogous to two hydrogen bonding networks is
investigated. The hydrogen bonding networks are extracted
from â-lactamase protein and are formed in its active site.
Each hydrogen bond of the network is described in equivalent
electrical circuit by three or four-terminal block-element.
Each block-element is coded in Matlab. Static and dynamic
analyses are performed. The resultant microelectronic circuit
analogous to the hydrogen bonding network operates as
current mirror, sine pulse source, triangular pulse source as
well as signal modulator.
Texture Unit based Monocular Real-world Scene Classification using SOM and KN...IDES Editor
In this paper a method is proposed to discriminate
real world scenes in to natural and manmade scenes of similar
depth. Global-roughness of a scene image varies as a function
of image-depth. Increase in image depth leads to increase in
roughness in manmade scenes; on the contrary natural scenes
exhibit smooth behavior at higher image depth. This particular
arrangement of pixels in scene structure can be well explained
by local texture information in a pixel and its neighborhood.
Our proposed method analyses local texture information of a
scene image using texture unit matrix. For final classification
we have used both supervised and unsupervised learning using
K-Nearest Neighbor classifier (KNN) and Self Organizing
Map (SOM) respectively. This technique is useful for online
classification due to very less computational complexity.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.