The document analyzes heat transfer for perforated fins under natural convection. Experiments were conducted using an array of 15 rectangular fins with 18 circular perforations extending through the thickness. The temperature distribution is examined for various perforation diameters. The heat transfer rate and coefficient increase with diameter. Mathematical models are developed to calculate the temperature distribution, heat dissipation rate, efficiency, effectiveness, surface area, and heat transfer coefficient. Equations account for parameters like perforation number, shape, spacing, and open area ratio. The analysis finds that perforated fins have higher heat transfer compared to non-perforated fins.
Experimental Analysis Of Heat Transfer From Square Perforated Fins In Stagger...IJERA Editor
This project gives the experimental analysis of heat transfer over a flat surface equipped with Square perforated
pin fins in staggered arrangement in a rectangular channel. The Fin dimensions are 100mm in height & 25mm in
width. The range of Reynolds number is fixed & about 13,500– 42,000, the clearance ratio (C/H) 0, 0.33 and 1,
the inter-fin spacing ratio (Sy /D) 1.208, 1.524, 1.944 and 3.417. Sy i.e. stream wise distance is varies and Sx i.e.
span wise distance is constant. The friction factor, enhancement efficiency and heat transfer correlate in
equations with each other. Here we are comparing Square pin fins with cylindrical pin fins. Staggered
arrangement and perforation will enhance the heat transfer rate. Clearance ratio and inter-fin spacing ratio affect
on Enhancement efficiency. Both lower clearance ratio and lower inter-fin spacing ratio and comparatively lower
Reynolds number give higher thermal performance. Friction factor & Nusselt number are Key parameter which
relates with efficiency enhancement and heat transfer rate.
A Review Paper on Fin Efficiency Enhancementijtsrd
From the previous couple of decades no of endeavours have made by scientists to upgrade the rate of heat transfer with the utilization of fins by differing number of parameters. The parameters like fin geometries, fin spacing, temperature dissemination, height, length have been explored in this paper. The paper gives some short audits about the methods for improving the rate of heat transfer by use of fins. Principle thought process of the paper is to give some concise information about the efficiency enhancements that can be made in fins to improve heat transfer rate. Naveen Kumar | Udit Singhal "A Review Paper on Fin Efficiency Enhancement" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29543.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/29543/a-review-paper-on-fin-efficiency-enhancement/naveen-kumar
Experimental Analysis Of Heat Transfer From Square Perforated Fins In Stagger...IJERA Editor
This project gives the experimental analysis of heat transfer over a flat surface equipped with Square perforated
pin fins in staggered arrangement in a rectangular channel. The Fin dimensions are 100mm in height & 25mm in
width. The range of Reynolds number is fixed & about 13,500– 42,000, the clearance ratio (C/H) 0, 0.33 and 1,
the inter-fin spacing ratio (Sy /D) 1.208, 1.524, 1.944 and 3.417. Sy i.e. stream wise distance is varies and Sx i.e.
span wise distance is constant. The friction factor, enhancement efficiency and heat transfer correlate in
equations with each other. Here we are comparing Square pin fins with cylindrical pin fins. Staggered
arrangement and perforation will enhance the heat transfer rate. Clearance ratio and inter-fin spacing ratio affect
on Enhancement efficiency. Both lower clearance ratio and lower inter-fin spacing ratio and comparatively lower
Reynolds number give higher thermal performance. Friction factor & Nusselt number are Key parameter which
relates with efficiency enhancement and heat transfer rate.
A Review Paper on Fin Efficiency Enhancementijtsrd
From the previous couple of decades no of endeavours have made by scientists to upgrade the rate of heat transfer with the utilization of fins by differing number of parameters. The parameters like fin geometries, fin spacing, temperature dissemination, height, length have been explored in this paper. The paper gives some short audits about the methods for improving the rate of heat transfer by use of fins. Principle thought process of the paper is to give some concise information about the efficiency enhancements that can be made in fins to improve heat transfer rate. Naveen Kumar | Udit Singhal "A Review Paper on Fin Efficiency Enhancement" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-1 , December 2019, URL: https://www.ijtsrd.com/papers/ijtsrd29543.pdf Paper URL: https://www.ijtsrd.com/engineering/mechanical-engineering/29543/a-review-paper-on-fin-efficiency-enhancement/naveen-kumar
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.
Comparative Study of Heat Transfer Enhancement in Rectangular And Interruped ...IJERDJOURNAL
Abstract: To increase the heat transfer rate of heat exchanger through fins in compact regionthe louvered interrupted plate fins has designed for increasing fins surface area. FLUENT and Multi-physics software are used in order to develop a 3-D numerical model for investigation ofinterrupted louvered fins. ILF analyzed by CFD tool, on the basis of geometrical parameters the compact relationship for Nusselt Number exhibits enhancement of thermal performance. Fin-plate weight reduces while surface area increases. Air is taken as the working fluid andThe flow regime is assumed to be turbulence, and the mean velocity is such that the Reynolds numbers of interest are above the critical Reynolds number. This study gives a performance data for a rectangular fin in simple and ILF in a plate-fin heat exchanger. In order to evaluate the performance, bulk temperature and combined span wise average Nusselt number (Nusa) are calculated. The heat transferenhancement is observed with the use of different interruption angles of 300 , 400 and 50
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
The aim of this article is to compare the design of Shell and Tube Heat Exchanger with baffles. Baffles used in
shell and tube heat exchanger improve heat transfer and also result in increased pressure drop. Shell and tube
heat exchanger with single segmental baffles was designed with same input parameters using 1) Kern’s
theoretical method; 2) ASPEN simulation software and 3) HTRI simulation software 4) SOLIDWORKS
simulation software. Shell side pressure drop and heat transfer coefficient are predicted. The results of all the
three methods indicated the results in a close range. The proven theoretical methods are in good agreement with
the simulation results
Analysis of Natural Convention Heat Transfer Enhancement in Finned Tube Heat ...journal ijrtem
ABSTRACT: Most of the engineering problems require high performance heat transfer components with progressively less weight, volumes, accommodating shapes and costs. Air cooled heat exchangers are subjected to air on outer side of heat exchanger surface on in heat recovery systems like economizers gases are subjected on one side of tube surface. On air or gas side heat transfer coefficient is less. Extended surface (fins) are one of the next exchanging devices that are employed extensively to increase heat transfer rates from tubular heat exchangers. The rate of heat transfer depends on the surface area of fin available for exchanging the heat transfer rate from the primary surface of cylindrical shape. Present study focuses on enhancement of heat transfer by using both circular and elliptical type of fins. The present paper attempts to examine trend of heat transfer coefficient experimentally and by using CFD software for various types of elliptical fins with i) varying elliptical ratio, ii) changing orientation of mounting of heat exchanger tube with elliptical fins, iii) varying spacing or fin density. KEY WORDS: Natural convection, Heat transfer enhancements, Elliptical fin, Fin orientation, Fin density.
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
Review of heat transfer augmentation for cooling of turbine blade tip by geom...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
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.
Heat transfer augmentation in different geometries of dimpled surface under n...eSAT Journals
Abstract The prime objective of present work is to study experimentally the heat transfer augmentation through various geometries of dimpled surfaces in longitudinal and lateral directions. In this paper horizontal rectangular plates of copper and aluminum with different dimpled geometries (like square, circular and triangular) for in-line arrangements were studied in natural convection with steady laminar external flow condition. The various parameters considered for study are Nusselt number, heat transfer coefficient and heat transfer rate for a constant Prandtl number (0.7) and Grashof number (104-107).It has been found that the heat transfer coefficient and heat transfer rate increases for various dimpled surfaces as compared to plane surface. It has been also found that the heat transfer coefficient and heat transfer rate increases along longitudinal direction as compared to lateral direction. And it is seen that heat transfer rate is maximum for triangular shape dimple when the apex of triangle is faced towards inlet of air flow Finally it is concluded that heat transfer enhancement takes place along the dimpled surface
Heat transfer augmentation in different geometries of dimpled surface under n...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.
CFD Analysis of Natural Convection Flow through Inclined EnclosureIJMERJOURNAL
ABSTRACT : The Natural convective laminar flow of two dimensional inclined rectangular enclosures is investigated by computational fluid dynamic analysis (fluent) in ansys.The upper and right wall keep adiabatic and other two walls are held in at different temperatures. The Rayleigh No varies from 103 to 106 to study the natural convection. The effect of inclination angle of the square and rectangle cavity on natural convection flow is studied for each combination of Rayleigh No. The effect of stream function and temperature contour show similar properties at low Rayleigh No. and it goes increases and show different pattern at high Rayleigh No
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.
Experiment on single-mode feedback control of oscillatory thermocapillary con...IJERA Editor
Feedback control was carried out on nonlinear thermocapillary convections in a half-zone liquid bridge of a high
Prandtl number fluid under normal gravity. In the liquid bridge, the convection changed from a two-dimensional
steady flow to a three-dimensional oscillatory flow at a critical temperature difference. Feedback control was
realized by locally modifying the free surface temperature using local temperature measured at different
positions. The present study aims to confirm whether the control method can effectively suppress oscillatory
flows with every modal structure. Consequently, the control was theoretically verified to be effective for
oscillatory flows with every modal structure in a high Marangoni number range.
Numerical Analysis of Inverted Notched Fin Array Using Natural ConvectionIOSR Journals
Abstract:Geometry and orientation plays an important role in natural convection heat transfer. For
horizontal rectangular fin array a chimney flow pattern is developed due to density difference. This flow
pattern creates a stagnant zone near central bottom region. That portion does not contribute much towards
heat dissipation. This area is removed from fins and they became inverted notched fins. This modified geometry
reduces material cost, material weight without hampering heat transfer rate. Numerical models are prepaid to
investigate heat transfer characteristics in plane fins and inverted notched fins. This investigation is also
extended over different types of notches and their effectiveness comparison. Fin spacing, fin height, fin length,
heater input, percentage of area removed in the form of inverted notch are the parameters under
consideration. This analysis is done numerically using CFD package (Fluent). It is found that the heat transfer
coefficient of inverted notch fin array is 25% to 35% higher as compared with normal fin array. Also we found
that the triangular shape notch gives better result than trapezoidal and rectangular shape notch.
Key words: Inverted Notched Fin, Chimney Flow, Natural Convection, Heat transfer coefficient enhancement
Improved Thermal Performance of Solar Air Heater Using V-Rib with Symmetrical...IJERA Editor
The most efficient technique to increase the performance of solar air heater is to enhance the heat transfer by using artificial roughness in form of repeatedly used ribs on the absorbing heated absorber plate. In order to analyse the thermal performance and flow pattern of rectangular duct with aspect ratio (W/H) of 8, the present experimental investigation is performed with V-rib with Symmetrical Gap and Staggered Rib. The experiment has covered a Reynolds number (Re) range of 3000-14000, rib height 2 mm, pitch (P) 24mm, relative roughness pitch (P/e) of 12, gap width (g) 8mm, relative gap width (g/e) as 4 and angle of attack (α) 60o , number of gaps on each sides of V-rib (Ng) 3, relative roughness height (e/Dh) 0.045, staggered rib pitch (P’) 15.6mm, relative staggered rib pitch (P’/P) 0.65, staggered rib size (w) 20mm and relative staggered rib size (w/g) 2.5. Results have been compared with the smooth plate under similar flow condition to determine the enhancement in heat transfer and improvement in efficiency. Relative staggered rib pitch was kept at 0.65 and staggered rib size was kept as 2.5 times gap width.
EFFECT THE FORM OF PERFORATION ON THE HEAT TRANSFER IN THE PERFORATED FINSOzyegin University
Extended surface heat exchangers are easy in construction and extensively use in
many of the industries. Continuous research is going on to improve its effectiveness
by reducing the thermal boundary layer thickness and increasing the heat transfer
surface area. Perforations in the fins one way that used to improve its effectiveness.
An experimental study submitted to investigate the heat transfer by natural
convection in a rectangular perforated fin plates. Five fins used in this work first fin
non-perforated and others fins perforated by different shapes these fins perforation
by different shapes (circle, square, triangle, and hexagon) but these perforations have
the same cross section area(113 mm2. These perforations distributed on 3 columns
and 6 rows. Experiments produced through in an experimental facility that was
specifically design and constructed for this purpose.
The results show that the drop in the temperature of the non-perforated fin from 72 to
57 oC while the temperature drop in perforated fins, at the same power supplied (126
W) was (72-52 oC), (72-51.5 oC), (72-50 oC) and (72 -48 oC) for shapes (hexagonal,
square, circular and triangular) respectively Figure(9). The largest value of RAF at
triangular perforation and the smaller value occurred in circular perforation. Also,
triangular perforation gives best values of heat transfer coefficient and then the
circular, square, hexagonal, and non-perforation respectively.
Keywords: Heat transfer, Surface heat exchangers, Perforated fin plates
EXPERIMENTAL STUDY OF HEAT TRANSFER FROM PLATE FIN ARRAY IN MIXED CONVECTION ...ijiert bestjournal
The work summarized in this paper presents an exper imental study of heat transfer from plate fin in mixed convection mode enhancement by the us e of plate fins is presented. After a brief review of the basic methods used to enhance the hea t transfer by simultaneous increase of heat transfer surface area as well as the heat tran sfer coefficient,a simple experimental method to assess the heat transfer enhancement is p resented. The method is demonstrated on plate fins as elements for the heat transfer enhanc ement,but it can in principle be applied also to other fin forms. That is varying various paramet ers (height,spacing). The order of the magnitude of heat transfer enhancement obtained exp erimentally,it was found that by a direct comparison of Nu and Re no conclusion regarding the relative performances could be made. This is because the dimensionless variables are int roduced for the scaling of heat transfer and pressure drop results from laboratory to large scal e but not for the performance comparison. Therefore a literature survey of the performance co mparison methods used in the past was also performed. Experiments will carried out on mix ed convection heat transfer from plate fin heat sinks subject to the influence of its geometry and heat flux. A total of 9 plate fins were pasted into the upper surface of the base plate. Th e area of the base plate is 150mm by 150mm. The base plate and the fins were made of alu minum. For all tested plate fin heat sinks,however,the heat transfer performance for h eat sinks with plate fins was better than that of solid pins.
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.
EXPERIMENTAL STUDY OF MIXED CONVECTION HEAT TRANSFER USING CIRCULAR, SQUARE, ...ijiert bestjournal
Pulling Fins are extended surfaces employed to enha nce the convective heat transfer from a surface for increasing heat dissipation. Fins with various geometries have been designed and used in various cooling application the selection o f particular fins configuration in any heat transfer application is an important state in desig ned process and takes into account the space,weight,manufacturing technique and cost considerat ion as well as the thermal characteristics it exhibits. Fins cross section profiles have profo und influence on thermal characteristics of Annular Fins and the surface area changes with chan ge of cross section of fins. This study deals with studying the performance of various avai lable fins profiles. Widely used fins profile viz. Rectangular,Triangular,Trapezoidal,Circular,Rhombic,and Elliptical Fins. In Addition to the normal configuration of fins,to ne w configurations were designed and created.
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.
Comparative Study of Heat Transfer Enhancement in Rectangular And Interruped ...IJERDJOURNAL
Abstract: To increase the heat transfer rate of heat exchanger through fins in compact regionthe louvered interrupted plate fins has designed for increasing fins surface area. FLUENT and Multi-physics software are used in order to develop a 3-D numerical model for investigation ofinterrupted louvered fins. ILF analyzed by CFD tool, on the basis of geometrical parameters the compact relationship for Nusselt Number exhibits enhancement of thermal performance. Fin-plate weight reduces while surface area increases. Air is taken as the working fluid andThe flow regime is assumed to be turbulence, and the mean velocity is such that the Reynolds numbers of interest are above the critical Reynolds number. This study gives a performance data for a rectangular fin in simple and ILF in a plate-fin heat exchanger. In order to evaluate the performance, bulk temperature and combined span wise average Nusselt number (Nusa) are calculated. The heat transferenhancement is observed with the use of different interruption angles of 300 , 400 and 50
Comparison of Shell and Tube Heat Exchanger using Theoretical Methods, HTRI, ...IJERA Editor
The aim of this article is to compare the design of Shell and Tube Heat Exchanger with baffles. Baffles used in
shell and tube heat exchanger improve heat transfer and also result in increased pressure drop. Shell and tube
heat exchanger with single segmental baffles was designed with same input parameters using 1) Kern’s
theoretical method; 2) ASPEN simulation software and 3) HTRI simulation software 4) SOLIDWORKS
simulation software. Shell side pressure drop and heat transfer coefficient are predicted. The results of all the
three methods indicated the results in a close range. The proven theoretical methods are in good agreement with
the simulation results
Analysis of Natural Convention Heat Transfer Enhancement in Finned Tube Heat ...journal ijrtem
ABSTRACT: Most of the engineering problems require high performance heat transfer components with progressively less weight, volumes, accommodating shapes and costs. Air cooled heat exchangers are subjected to air on outer side of heat exchanger surface on in heat recovery systems like economizers gases are subjected on one side of tube surface. On air or gas side heat transfer coefficient is less. Extended surface (fins) are one of the next exchanging devices that are employed extensively to increase heat transfer rates from tubular heat exchangers. The rate of heat transfer depends on the surface area of fin available for exchanging the heat transfer rate from the primary surface of cylindrical shape. Present study focuses on enhancement of heat transfer by using both circular and elliptical type of fins. The present paper attempts to examine trend of heat transfer coefficient experimentally and by using CFD software for various types of elliptical fins with i) varying elliptical ratio, ii) changing orientation of mounting of heat exchanger tube with elliptical fins, iii) varying spacing or fin density. KEY WORDS: Natural convection, Heat transfer enhancements, Elliptical fin, Fin orientation, Fin density.
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
Review of heat transfer augmentation for cooling of turbine blade tip by geom...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
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.
Heat transfer augmentation in different geometries of dimpled surface under n...eSAT Journals
Abstract The prime objective of present work is to study experimentally the heat transfer augmentation through various geometries of dimpled surfaces in longitudinal and lateral directions. In this paper horizontal rectangular plates of copper and aluminum with different dimpled geometries (like square, circular and triangular) for in-line arrangements were studied in natural convection with steady laminar external flow condition. The various parameters considered for study are Nusselt number, heat transfer coefficient and heat transfer rate for a constant Prandtl number (0.7) and Grashof number (104-107).It has been found that the heat transfer coefficient and heat transfer rate increases for various dimpled surfaces as compared to plane surface. It has been also found that the heat transfer coefficient and heat transfer rate increases along longitudinal direction as compared to lateral direction. And it is seen that heat transfer rate is maximum for triangular shape dimple when the apex of triangle is faced towards inlet of air flow Finally it is concluded that heat transfer enhancement takes place along the dimpled surface
Heat transfer augmentation in different geometries of dimpled surface under n...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.
CFD Analysis of Natural Convection Flow through Inclined EnclosureIJMERJOURNAL
ABSTRACT : The Natural convective laminar flow of two dimensional inclined rectangular enclosures is investigated by computational fluid dynamic analysis (fluent) in ansys.The upper and right wall keep adiabatic and other two walls are held in at different temperatures. The Rayleigh No varies from 103 to 106 to study the natural convection. The effect of inclination angle of the square and rectangle cavity on natural convection flow is studied for each combination of Rayleigh No. The effect of stream function and temperature contour show similar properties at low Rayleigh No. and it goes increases and show different pattern at high Rayleigh No
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.
Experiment on single-mode feedback control of oscillatory thermocapillary con...IJERA Editor
Feedback control was carried out on nonlinear thermocapillary convections in a half-zone liquid bridge of a high
Prandtl number fluid under normal gravity. In the liquid bridge, the convection changed from a two-dimensional
steady flow to a three-dimensional oscillatory flow at a critical temperature difference. Feedback control was
realized by locally modifying the free surface temperature using local temperature measured at different
positions. The present study aims to confirm whether the control method can effectively suppress oscillatory
flows with every modal structure. Consequently, the control was theoretically verified to be effective for
oscillatory flows with every modal structure in a high Marangoni number range.
Numerical Analysis of Inverted Notched Fin Array Using Natural ConvectionIOSR Journals
Abstract:Geometry and orientation plays an important role in natural convection heat transfer. For
horizontal rectangular fin array a chimney flow pattern is developed due to density difference. This flow
pattern creates a stagnant zone near central bottom region. That portion does not contribute much towards
heat dissipation. This area is removed from fins and they became inverted notched fins. This modified geometry
reduces material cost, material weight without hampering heat transfer rate. Numerical models are prepaid to
investigate heat transfer characteristics in plane fins and inverted notched fins. This investigation is also
extended over different types of notches and their effectiveness comparison. Fin spacing, fin height, fin length,
heater input, percentage of area removed in the form of inverted notch are the parameters under
consideration. This analysis is done numerically using CFD package (Fluent). It is found that the heat transfer
coefficient of inverted notch fin array is 25% to 35% higher as compared with normal fin array. Also we found
that the triangular shape notch gives better result than trapezoidal and rectangular shape notch.
Key words: Inverted Notched Fin, Chimney Flow, Natural Convection, Heat transfer coefficient enhancement
Improved Thermal Performance of Solar Air Heater Using V-Rib with Symmetrical...IJERA Editor
The most efficient technique to increase the performance of solar air heater is to enhance the heat transfer by using artificial roughness in form of repeatedly used ribs on the absorbing heated absorber plate. In order to analyse the thermal performance and flow pattern of rectangular duct with aspect ratio (W/H) of 8, the present experimental investigation is performed with V-rib with Symmetrical Gap and Staggered Rib. The experiment has covered a Reynolds number (Re) range of 3000-14000, rib height 2 mm, pitch (P) 24mm, relative roughness pitch (P/e) of 12, gap width (g) 8mm, relative gap width (g/e) as 4 and angle of attack (α) 60o , number of gaps on each sides of V-rib (Ng) 3, relative roughness height (e/Dh) 0.045, staggered rib pitch (P’) 15.6mm, relative staggered rib pitch (P’/P) 0.65, staggered rib size (w) 20mm and relative staggered rib size (w/g) 2.5. Results have been compared with the smooth plate under similar flow condition to determine the enhancement in heat transfer and improvement in efficiency. Relative staggered rib pitch was kept at 0.65 and staggered rib size was kept as 2.5 times gap width.
EFFECT THE FORM OF PERFORATION ON THE HEAT TRANSFER IN THE PERFORATED FINSOzyegin University
Extended surface heat exchangers are easy in construction and extensively use in
many of the industries. Continuous research is going on to improve its effectiveness
by reducing the thermal boundary layer thickness and increasing the heat transfer
surface area. Perforations in the fins one way that used to improve its effectiveness.
An experimental study submitted to investigate the heat transfer by natural
convection in a rectangular perforated fin plates. Five fins used in this work first fin
non-perforated and others fins perforated by different shapes these fins perforation
by different shapes (circle, square, triangle, and hexagon) but these perforations have
the same cross section area(113 mm2. These perforations distributed on 3 columns
and 6 rows. Experiments produced through in an experimental facility that was
specifically design and constructed for this purpose.
The results show that the drop in the temperature of the non-perforated fin from 72 to
57 oC while the temperature drop in perforated fins, at the same power supplied (126
W) was (72-52 oC), (72-51.5 oC), (72-50 oC) and (72 -48 oC) for shapes (hexagonal,
square, circular and triangular) respectively Figure(9). The largest value of RAF at
triangular perforation and the smaller value occurred in circular perforation. Also,
triangular perforation gives best values of heat transfer coefficient and then the
circular, square, hexagonal, and non-perforation respectively.
Keywords: Heat transfer, Surface heat exchangers, Perforated fin plates
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The work summarized in this paper presents an exper imental study of heat transfer from plate fin in mixed convection mode enhancement by the us e of plate fins is presented. After a brief review of the basic methods used to enhance the hea t transfer by simultaneous increase of heat transfer surface area as well as the heat tran sfer coefficient,a simple experimental method to assess the heat transfer enhancement is p resented. The method is demonstrated on plate fins as elements for the heat transfer enhanc ement,but it can in principle be applied also to other fin forms. That is varying various paramet ers (height,spacing). The order of the magnitude of heat transfer enhancement obtained exp erimentally,it was found that by a direct comparison of Nu and Re no conclusion regarding the relative performances could be made. This is because the dimensionless variables are int roduced for the scaling of heat transfer and pressure drop results from laboratory to large scal e but not for the performance comparison. Therefore a literature survey of the performance co mparison methods used in the past was also performed. Experiments will carried out on mix ed convection heat transfer from plate fin heat sinks subject to the influence of its geometry and heat flux. A total of 9 plate fins were pasted into the upper surface of the base plate. Th e area of the base plate is 150mm by 150mm. The base plate and the fins were made of alu minum. For all tested plate fin heat sinks,however,the heat transfer performance for h eat sinks with plate fins was better than that of solid pins.
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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.
EXPERIMENTAL STUDY OF MIXED CONVECTION HEAT TRANSFER USING CIRCULAR, SQUARE, ...ijiert bestjournal
Pulling Fins are extended surfaces employed to enha nce the convective heat transfer from a surface for increasing heat dissipation. Fins with various geometries have been designed and used in various cooling application the selection o f particular fins configuration in any heat transfer application is an important state in desig ned process and takes into account the space,weight,manufacturing technique and cost considerat ion as well as the thermal characteristics it exhibits. Fins cross section profiles have profo und influence on thermal characteristics of Annular Fins and the surface area changes with chan ge of cross section of fins. This study deals with studying the performance of various avai lable fins profiles. Widely used fins profile viz. Rectangular,Triangular,Trapezoidal,Circular,Rhombic,and Elliptical Fins. In Addition to the normal configuration of fins,to ne w configurations were designed and created.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
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NATURAL CONVECTION HEAT TRANSFER INSIDE INCLINED OPEN CYLINDERIAEME Publication
Natural convection is investigated experimentally in an inclined open cylindrical passege heated under 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 cylinder diameter of 4.8 cm, cylinder length 50 cm and heat flux from 70 W/m2 to 600 W/m2 . Empirical correlations are given for the average Nusselt number as a function of the
Rayleigh number. 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 obtained.
Research Inventy : International Journal of Engineering and Scienceinventy
Research Inventy : International Journal of Engineering and Science
Research Inventy : International Journal of Engineering and Science is published by the group of young academic and industrial researchers with 12 Issues per year. It is an online as well as print version open access journal that provides rapid publication (monthly) of articles in all areas of the subject such as: civil, mechanical, chemical, electronic and computer engineering as well as production and information technology. The Journal welcomes the submission of manuscripts that meet the general criteria of significance and scientific excellence. Papers will be published by rapid process within 20 days after acceptance and peer review process takes only 7 days. All articles published in Research Inventy will be peer-reviewed
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constant heat flux of 529 W/m2 by other internal tube which was an electric element with 6.3 mm diameter and 600mm length. The pipe kit was rotated by ten declination angles, which were varied from (0O to 90O ) by 10O for each step.
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.
Analysis of A Double Spiral Counter Flow Calorimeter in Impinging Flame Jet U...IJERA Editor
Enhancement of heat transfer rates in heat exchanger and calorimeter has been reported by many researchers. However, work regarding heat transfer characteristics analysis of double spiral counter flow calorimeter is not published and this forms the objective of this work. DSCFC is a unique design where it consists of single fluid as working fluid for heat exchange. Here heat transfer takes place between solid and fluid, and hence can be called as conjugate heat transfer problem. Heat transfer characteristics DSCFC is observed at various Reynolds number and base temperature. DSCFC is analyzed considering conjugate heat transfer and temperature dependent properties of heat transport media. Computations are performed using commercially available CFD package ANSYS-CFX. It is observed that with increase in Reynolds number of the fluid, heat transfer reduces whereas increase in base temperature increases heat transfer. The Computational results are compared with the experimental.
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with Reynolds number ranged from 3442.6 to 17213.19 under constant wall heat flux.
Experimental results show obtained for average Nusselt numbers and friction factor.
The results indicate that the trapezoidal baffled geometry provides a higher thermal
performance than the other type baffled one. The present work showed that the highest
thermal performance factor under the same pumping power obtained from the
experiments, is about 2.26 times more than that of plain duct. Also, it is found that the
thermal performance of the baffles attach on the bottom wall of the duct is higher than
the other baffles attach on the top
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.
Cascaded Thermodynamic and Environmental Analyses of Energy Generation Modali...Ozyegin University
This study presents cascaded thermodynamic and environmental analyses of a high-performance academic building. Five different energy efficiency measures and operation scenarios are evaluated based on the actual measurements starting from the initial design concept. The study is to emphasize that by performing dynamical energy, exergy, exergoeconomic, and environmental analyses with increasing complexity, a better picture of building performance indicators can be obtained for both the building owners and users, helping them to decide on different investment strategies. As the first improvement, the original design is modified by the addition of a ground-air heat exchanger for pre-conditioning the incoming air to heat the ground floors. The installation of roof-top PV panels to use solar energy is considered as the third case, and the use of a trigeneration system as an energy source instead of traditional boiler systems is considered as the fourth case. The last case is the integration of all these three alternative energy modalities for the building. It is determined that the use of a trigeneration system provides a better outcome than the other scenarios for decreased energy demand, for cost reduction, and for the improved exergy efficiency and sustainability index values relative to the original baseline design scenario. Yet, an integrated approach combining all these energy generation modalities provide the best return of investment.
An experimental and analytical study to show the effect of theOzyegin University
The main purpose of this paper is showing the enhancement of thermal conductivity
of the epoxy with many percentages of carbon fiber into it. In addition to pure epoxy and pure
carbon fiber, three percentages of carbon fiber are used in this study, which are 20, 40, and 60%,
respectively. All of these samples are tested at different values of applied powers (input power)
(10, 25, 40, 55, and 70 W). A comparison between pure epoxy, pure carbon fiber and the
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these simples on the performances of both Aluminum and cooper heat sinks.
It is shown from the results that increasing in fiber carbon percentage leads to increase in
thermal conductivity of composite, heat sink junction temperature, overall heat sink efficiency,
and density of composite. The increasing in overall heat sink efficiency leads to decrease the
height of heat sink, and consequently decreasing its cost. For instance at 70 W power input,
increasing the fiber carbon percentage(from 0 to 100%) for each material of heat sink, leads to
decrease the average fin length by 48% ,decrease the manufacturing cost by 47%, increase in
junction temperature by 65 %, and increase fin efficiency by 2.5 %.
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on environmental pollution, the study included two samples of diesel fuel.,
first sample is used currently in all diesel engines vehicles, and it produced in
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of the Lubricating oils and kerosene with ratio
(1/40), were prepared and tested in research laboratories and quality control of
the North Refineries Company /BAIJI by using standard engine (CFR).
comparison between two models of fuel in terms of the properties of the
mixing fuel and the properties of diesel fuel standard. The results proved that
the process of mixing these , leading to the minimization of Cetane number
and flash point. While the viscosity increase in mixing fuel, comparison with
fuel producer in the refinery, and which identical to the minimum standard
specifications of diesel fuel.
Experimental Study of the Effect of Octane Number on the Performance Coeffici...Ozyegin University
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(TD113), with compression ratio of (7.3:1) Coupled to hydraulic dynamometer type
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The results showed that there is enhancement of the engine performance with
increasing octane number. This appears clearly when comparing the results of
performance with fuel of 75 and 95 octane number.
The torque increases 10% at speed of 2750 RPM. The break power also
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The results proved that it is possible to control the entering mixture temperature which enters to the I.C.E. by controlling to the speed of rotary exchanger. The results were that, at the temperatures of the environment 5oC and 10 oC it was prove that the RPM of the exchanger should be 10 RPM, also at the environment temperatures 20,30, and 40 oC ,the rotation speed should be within the ranges (3-10),(2-5.5) and (1-2) RPM respectively. In order to guarantee staying the entering mixture temperature within, the required range.
KEYWORDS
Thermal Storage, I.C. Engine, Rotary Heat Exchanger
- )27 27(
27
DETERMINATION OF THE TEMPERATURE DISTRIBUTION THE PERFORATED FINS UNDER NATUR...Ozyegin University
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KEYWORDS: Perforated Fins, Temperature Distribution, Natural Convection.
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DETERMINATION OF THE TEMPERATURE DISTRIBUTION THE PERFORATED FINS UNDER NATURAL CONVECTION
1. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
DETERMINATION OF THE TEMPERATURE DISTRIBUTION THE
PERFORATED FINS UNDER
NATURAL CONVECTION
Dr. Aziz M. Mhamuad Thamir Kh. Ibrahim Raid R. Jasim
Lecturer Assistant Lecturer Assistant Lecturer
Chemical Eng.Dept. Mechanical Eng. Dept
Technical Institute Tikrit University
Mousl
ABSTRACT
This work treats the problem of heat transfer for perforated fins under natural
convection. The temperature distribution is examined for an array of rectangular fins (15
fins) with uniform cross-sectional area (100x270 mm) embedded with various vertical
body perforations that extend through the fin thickness. The patterns of perforations
include 18 circular perforations (holes). Experiments were carried out in an experimental
facility that was specifically design and constructed for this purpose. The heat transfer
rate and the coefficient of heat transfer increases with perforation diameter increased.
KEYWORDS: Perforated Fins, Temperature Distribution, Natural Convection.
Nomenclature
symbol Definition unit
k thermal conductivity
of fin material
w/o
C m
L Fin length m
Nu Nusselt number of
the fin surface
-
Nc Total number of
perforations in the fin
Nx Number of
perforations in
longitudinal direction
of the fin
Ny Number of
perforations in ll
direction of the fin
-
OA Open area of
perforated surface
m2
63
2. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
OAmax Maximum open area
of perforated surface
m2
Qf Heat dissipation rate
from the non-
perforated fin
W
Qf,max Heat dissipation rate
from the non-
perforated fin
W
RAF Ratio of heat transfer
surface area of the
perforated fin to that
of the non-perforated
fin
-
REF Ratio of the
perforated fin
efficiency to that of
the non-perforated fin
-
REP Ratio of the
perforated fin
effectiveness to that
of the non-perforated
fin
-
RWF Ratio of weight of the
perforated fin to that
of the non-perforated
fin
-
Sx Longitudinal spacing
of the perforation
m
Sy Transverse spacing of
the perforation
m
.t Fin thickness m
T Temperature o
C
Tb Temperature of the
fin base
o
C
Ta Ambient temperature o
C
W Fin width m
ηf Efficiency of the non-
perforated fin
-
ηfp Efficiency of the
perforated fin
-
εf: Effectiveness of the
non-perforated fin
-
εfp : Effectiveness of the
perforated fin
-
ρ Density of the fin
material
kg/m3
INTRODUCTION
One of the basic objectives in design
heat exchanger surfaces for enhanced
heat transfer is to breakup or disrupts
thick laminar boundary layers. Usually
this is accomplished by introducing
obstructions into the flow or by forming
channels which cause local changes in
the mean flow direction.
Heat transfer from extended surfaces
for a given fin material, base
temperature, and ambient temperature
can be enhanced by increasing the heat
transfer coefficient and / or by increasing
the effective heat transfer surface area[1]
.
64
3. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
Heat transfer coefficient of the fin
surface can be increased by introducing
surface roughness and hence promoting
turbulence. As for surface area, the
literature introduces several methods
used to increase the effective heat
transfer surface area of fins such as [2,3,4]
:
1-The use of fins comprising rough
surface.
2-The use of grooved and serrated fins.
3-The use of louvered fins.
4-The use of slotted and perforated fins.
5-The use of augmented fins.
Perforated fins are widely used in
plate-fin heat exchangers , film cooling
turbine blades , and most recently in a
new type of solar collectors used to heat
ambient air [1,5]
Perforated fins can be used to
increase the heat transfer coefficient
and /or effective heat transfer area. The
change in magnitude of the
surface area depends on the geometry of
the perforations[3]
.
Pin fins, cross-cut fins and
augmented fin are examples of the
innovations produced by various
manufacturers. They all have one thing
in common: the improved heat removal
surface has many shorter fin sections
that introduce thinner boundary layers
than one long fin of the same overall
length. Augmented fin allow a lower
temperature rise for an equal amount of
heat load [6]
. This fin's is now used in
cooling some internal combustion
engines; especially the engine which
uses in generated the electrical power
unit. This fin's now are used in cooling
internal combustion engines, specially
the engines which uses in generated the
electrical power, which are cooling by
natural convection.
PREVIOUS WORKS
A series of studies have been
conducted for determining the
performance of perforated and
augmentation heat transfer surfaces:
Liang and Yang[7]
examined the
effects of perforation geometry on the
heat transfer and friction loss
performance of compact heat exchangers
having plate perforated rectangular fin
surface.
Yang[8]
identified three distinct
types of augmentation in the heat
transfer and friction loss performance:
transition turbulent flow enhancement on
low porosity surface, laminar flow
65
4. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
enhancement on high porosity surface,
and the entire laminar flow region on
low porosity compposite surfaces
consisting of a short upstream section for
proding vortices and a mean section for
heat transfer.
Patankar & Prakash[3]
presented an
analysis for the flow and heat transfer in
an interrupted – plate passage, which is
an idealization of the offset fin heat
exchanger. The plates are considered to
be of finite thickness.
Mullisen & Loehrke[9]
tested arrays
of parallel plates in a wind tunnel to
identify the important parameters and
provide guidelines for designer of heat
transfer surfaces and to workers
attempting to correlate experimental
data. Three distinctly different flow
regimes were found within cores
composed of in-line plates. These are
classified as steady, general unsteady,
and periodic unsteady flows.
Fujii et.al[10]
studied experimentally
the mechanism of heat transfer
enhancement by changing the surface
geometries and heat exchanger
configuration. The surface has many
perforations and is bent to form a
trapezoidal shape. Dimensionless
correlations on the heat transfer and
pressure drop were presented.
Mousa[2]
examined theoretically
the thermal performance for a horizontal
rectangular fin with uniform cross-
sectional area embedded with four
vertical body perforation patterns that
extend through the fin thickness. The
patterns include circular, square,
triangular, and rectangular perforations.
Natural convection with finite element
technique was used to solve these
patterns in his study. The study showed
that heat transfer of the perforated fin is
larger than that of the non- perforated
fin.
MATHEMATICAL TREATMENT
Heat transfer analysis of the non-
perforated rectangular fin is based on the
analytical solution, based on the
following assumptions:
1. The heat conduction in the fin is
steady.
2. No heat generation in the fin
body.
3. Fin conductivity is constant.
4. The ambient temperature is
uniform.
5. The temperature at the base of
the fin is uniform.
66
5. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
mLmkhmL
xLmmkhxLm
TT
TT
b
x
sinh/cosh
sinh/cosh
6. Fin width (w) >> its thickness (t),
so the effect of the fin sides can
be neglected.
7. The heat transfer coefficient
assumed to be uniform over all
surface of the fin.
8. No radiation between the fin and
the surrounding.
Based upon these assumptions, the
temperature distribution along the
non-perforated fin is[1]
:
………..……………(1)
and heat dissipation rate:
)mLsinh()]mk/(h[)mLcosh(
)mLcosh()]mk/(h[)mLsinh(
TTm.kAQ bf
………. (2)
Where
kA
Ph
m
ft
, fP = peripheral
perimeter = 2W, A = cross sectional
area = W. t
The fin performance can be
evaluated by the fin efficiency (ηf) or
by the fin effectiveness ( f ). The fin
efficiency is defined as the ratio of
the heat transfer from the fin to the
heat transfer from the fin if its whole
body is maintained at the base
temperature. The fin effectiveness is
defined as the ratio of the heat
transfer rate to the heat transfer rate
that would exist without the fin[1]
.
max,f
f
f
Q
Q
…………… (3)
TTAh
Q
bb
f
f
.
…..… (4)
TThAhWLQ btf ..2max,
………… (5)
Also we can define the heat transfer
volume (V), and surface area (At) as:
tWLV ... …………..(6)
tWWLAt ..2 … …….(7)
GEOMETRICAL ANALYSIS OF
FIN PERFORATED
In this paper, the dimensions of
fin are known. Also the number of
perforations (Nx) in the x- direction
(L) and (Ny) in the y- direction (W)
can be assumed. The perforation
cross sectional area (Ac) may be
assumed, and then the dimension of
any perforation can be calculated.
The surface area of the uniform
longitudinal rectangular perforated
fin can be expressed as:
67
6. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
pcctpsfp ANAAA
cccc ANtWANLW ...2.2
cpcCf AANA 2 …… ……. (8)
Equation (8) can be written as :
cpcyxffp AANNAA 2. …... (9)
In order to compare the heat transfer
surface area of the perforated fin
(Afp) to that of the conventional one
(Af), the fin surface area ratio RAF is
introduced and is given by:
f
fp
A
A
RAF
f
cpcyx
A
AANN
RAF
2
1
. (10)
The material volume of the
perforated fin is compared with the
volume of non- perforated fin by
volume reduction ratio which given
by:
tWL
tANNtWL
V
V
RVF
cyx
f
fp
..
..
WL
ANN
RVF
cyx
.
..
1 ……. (11)
Similarly, perforated fin has less
weight than that of equivalent non-
perforated one. This aspect is
expressed by the fin weight
reduction ratio RWF defined as
follows:
f
cyxf
f
fp
W
tANNW
W
W
RWF
....
W.L
A.N.N
1
.t.W.L
.t.A.N.N
1RWF
cyxcyx
.
……..(12)
According to the perforation shape
and dimension that can be cut out
from the fin body, fin with the
circular perforation pattern is studied
.The number of perforation in
longitudinal direction (Nx), in the
transverse direction (Ny), and the
perforation diameter is (b). The
directional perforations spacing Sx
and Sy:
yxx SNbNL 1.
1
.
x
x
x
N
bNL
S …… ……. (13)
yyy SNbNW 1.
1
.
y
y
y
N
bNW
S … ……. (14)
The heat transfer surface area of the
fin can be expressed as:
pcccffp ANANAA ..2
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7. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
cpcf AANA 2
2
.
b
tbNA Cf ……. (15)
The ratio RAF and RVF can be
expressed as:
WtLW
b
tNNb
RAF
yx
.2
2
...
1
….(16)
and
LW
b
4
N.N
1RVF
2
yx
……. (17)
ANALYSIS OF HEAT
TRANSFER COEFICIENT
An experimental correlation to
estimate the convection heat transfer
coefficient of array of vertical
oriented parallel flat plate is given
by[11]
75.0
35
)1(
24
. Ra
e
Ra
k
Bh
Nu
…... (18)
Where
B is the average space between
adjacent fins.
L.k.
T.B.C..g.
Ra
4
p
2
……. (19)
Several studies[9,12,13]
reported that
the surface heat transfer coefficient
of perforated surfaces is a function of
open area ratio [ROA] of the
perforated surface . The open area
ratio is defined as:
maxOA
OA
ROA ……… ……. (20)
Where OA is the actual open area
cc NA .
yxc NNA .. …………(21)
OAmax is the maximum possible
perforations open area, which is
defined as:
max,ymax,xcmax,ccmax N.N.AN.AOA
…...(22)
where Nx,max and Ny,max are the
maximum possible number of the
perforations along the fin. These
numbers related with the perforation
spacing equal zero. The perforated
surface heat transfer coefficient ratio
can be expressed as[12]
:
max
h
OA
OA
75.01R … ……. (23)
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8. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
The film heat transfer coefficient of
the perforated surface (hps) is
expressed as:
h)
OA
OA
75.01(h
max
ps ………. (24)
EXPERIMENTAL WORK
The experiments were carried out in
an experimental facility that was
specifically designed and constructed for
this purpose. Figure (1) shows view of
the experimental apparatus.
The experimental setup includes a
heat sink supplied with heating elements
and data acquisition system,. The heat is
generated within the heat sink by means
of four heating elements each of 650 W
powers. All the experimental data are
recorded by the data acquisition system.
The components of the system used
to carry out the experiments are given
below:
Heat Sink Assembly
The heat sink chosen for experiments
Fig.(2) is aluminum cylinder of 100 mm
diameter and 270 mm length. Four holes
were drilled in the cylinder in which four
heating elements were pressed. The
power supplied by each element was 650
W. Fifteen aluminum straight fins were
fitted radialy.The fins are 100 mm long,
270 mm wide and 2 mm thick. These
fins were divided into five groups
equally :
A-non-perforated fins.
1. perforated fins with 8mm
diameter perforation.
2. perforated fins with 12mm
diameter perforation.
3. perforated fins with 16mm
diameter perforation.
4. perforated fins with 20mm
diameter perforation.
All groups include three fins and
we taken the middle of them as a test fin.
Power Supply Regulator
A variable transformer Fig(1) of type
50B with input 220V and 50-60Hz and
output 0-240V, 20A, and 7.5kVA was
used to regulate the voltage supplied to
the heating elements.
The measurement
The experimental data were
measured by thirty calibrated
thermocouples of type-K were used to
measure the temperature at different
locations necessary for this study. The
measured parameters and their ranges
during the experiments were listed
below:
70
9. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
Heat supplied: 100-900 W.
Perforation-shape: Circular.
Number of perforation: 18 per fin with
various diameter of perforation.
The temperatures of testing fins
were measured by using thirty
thermocouples of type–k. Three of these
thermocouples fixed on the outside
diameter of the aluminum cylinder in
order to measure the base temperatur of
the fin. Two thermocouple are used to
measure air temperature.
Twenty five of thermocouples
were divided into five groups equally
(the same number of fin groups). Each
group was fixed to the surface of the test
fin at equal space (20 mm) locations
along the fin length.
The apparatus was allowed to run
for about 100 minute, until the steady
state was attained. The recording of
temperature was started after steady state
had been reached.
RESULTS AND DISCUSTION
Equation (8) for the investigated
perforation shape geometry indicate that
the increase or decrease in surface area
of the perforated fin, with respect to that
of the non-perforated one, depends on
the following parameters: the total
number of perforation (Nc), the
perforation diameter(b),and the fin
thickness.
However, the above Equation also
imply that Afp is greater or smaller than
Af depending on the fin thickness (t) and
perforation diameter (b).
Equation (10) shows that the heat
transfer surface area of the perforated fin
is a function of the fin dimensions and
the perforation shape geometry. This
Equation can be used to calculate the
ratio of the heat transfer surface area of
the perforated fin to that of the non-
perforated one, RAF. It indicates that
RAF is a weak function of the fin length
and width. This is because the effect of
the fin tip area which is smaller
compared surface to that of the fin
surface area and can be neglected.
Figure (3) express the relation
between RAF and perforation diameter
(b). This figure shows that (RAF) is
smaller than unity.
Heat dissipation rate of the
perforated fin depends on the heat
transfer coefficient and fin area. In this
study, all the film heat transfer
coefficients are assumed to be uniform
and equal. It was mentioned before that
(Rh) s always greater than unity and
71
10. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
increasing up to the upper limit 1.75 as
the diameter (b) increased, but
decreasing down to the lower limit of 1.
The calculation of heat transfer
coefficient ratio Rh (Equation 23) was
plotted in Figure (4).
The temperature distribution along
the fin has important effect on the fin
performance. Higher fin temperatures
exist as the fin thermal resistance is
decreased. The temperature distribution
of the perforated fins and that non-
perforated along x-direction are plotted
in Figures (5) through (13). As shown in
figures, it is obvious that the
temperatures along the non-perforated
fin are higher than those of the
perforated one in most cases. These
figures indicate that the temperature
drop between the fin base and tip
increases as the perforation diameter
increased. This is because the thermal
resistance of the perforated fin decreases
as the perforation diameter is increased.
The perforated fin weight
reduction ratio (RWF) for the perforated
fin type can be calculated from Equation
(12). The ratio RWF is plotted as a
function of the perforation diameter (b)
in Figure (14). The figure shows that the
weight reduction ratio of the perforated
fin continues to decrease as b is
increased.
CONCLUSIONS
The rate of temperature drop
along the perforated fin length is
consistently larger than that for the
equivalent non-perforated fin. The gain
in heat dissipation rate for the perforated
fin is a strong function of both: the
perforation dimension and lateral
spacing. Decreasing the perforation
dimension reduces the rate of
temperature drop along the perforated
fin. Heat transfer coefficient for
perforated fin is larger than of non-
perforated one.
REFERENCES
1.Incropera, P. and Dewit, D.P.,
"Fundamentals of heat and mass
transfer", 5th
Edition, John wiley and
sons, 2001.
2.Mousa, A.H., "Enhancement of
thermal performance of fins subjected
to natural convection through body
perforation", Ph.D. thesis, Mech. Eng.,
Baghdad university, 2000.
3.Patankar, S.V., and Prakash., C., "An
analysis of the effect of plate thickness
on laminar flow and heat transfer in
72
11. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
interrupted plate passage", Int.J.H .T,
Vol.29, No.11, 1981.
4. Zelenk, R.L., and Loehrke, R.I.,
"Heat transfer from interrupted
plates", J. of H.T., Vol.105, 1983.
5. Jarrah, B.A., "Thermal optimization
of pin fin arrays experiencing forced
convection heat transfer", M.Sc.
Thesis, Jordon, 1996,
6. Mhamud, A.A., “Performance of
perforated and non-perforated fins”,
Ph.D. Thesis,Chemical Eng.,
University of Baghdad, 2005.
7. Liang, C.Y. and Yang, W.J., "Heat
transfer and friction loss
performance of perforated heat
exchanger surfaces", J. of H.T., Feb.
1975.
8. Yang., W.J., "Three kinds of heat
transfer augmentation in perforated
surfaces", Letters in H. and M.T.,
Vol.5, 1978.
9. Mullisen, R.S., and Loehrke, R.I., "A
steady of flow mechanism
responsible for heat transfer
enhancement in interrupted-plate
heat exchangers", J. of H.T.,
Vol.108, 1986.
10. Fujii, M. et.al., "Heat transfer and
pressure drop of perforated surface
heat exchanger with passage
enlargement and contraction",
Int.J.H.M.T., Vol.31, No.1, 1988.
11. Simmons R.E. .,"Estimation natural
convection heat transfer for arrays of
vertical parallel flat platter "
Electronics cooling, Feb. 2002
12. Kakaae,S., "Heat exchanger
thermal–hydraulic fundamentals ",
1989.
13. Rohsenow, W.M., Hartnett, J.P., and
Ganic, E.N., "Handbook of heat
transfer fundamentals", 2nd
Edition,
McGrew-Hill Book company, 1982.
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12. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
Heat
sink
Figure (1) View of the Experimental Apparatus
Figure (2) View of the Heat Sink (test section).
Power
supply
regulator
Thermocouple
Measure
ment
Devices
Heating
elements
Non perforated Fins
perforated
Fins with
20 mm D
perforated
Fins with
16 mm D
perforated
Fins with
12 mm D
8 mm D
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13. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
0 4 8 12 16 20
Perforation Daimeter (mm)
0.8
0.9
1.0RAF
Figure (3) the relation between ratio of
heat transfer surface area of perforated
fin to that of non perforated fin RAF and
perforation diameter.
0 4 8 12 16 20
Perforation Daimeter (mm)
0.9
1.0
1.1
1.2
1.3
Rh
Figure (4) The relation between
heat transfer coefficient ratio
( Rh )and perforation diameter.
0 20 40 60 80 100
Length (mm)
44
48
52
56
60
64
68
72
Temperature(C)
200W
Non
8 mm
12 mm
16 mm
20 mm
Figure (6) Temperature
Distribution with 200w
0 20 40 60 80 100
Length (mm)
34
36
38
40
42
44
46
48
50
52
Temperature(C)
100W
Non
8 mm
12 mm
16 mm
20 mm
Figure (5) Temperature
Distribution with 100w
75
14. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
0 20 40 60 80 100
Length (mm)
70
80
90
100
110
120
Temperature(C)
500W
Non
8 mm
12 mm
16 mm
20 mm
Figure (9) Temperature
Distribution with 500w
0 20 40 60 80 100
Length (mm)
70
80
90
100
110
120
130
140
150
Temperature(C)
600W
Non
8 mm
12 mm
16 mm
20 mm
Figure (10) Temperature
Distribution with 600w
0 20 40 60 80 100
Length (mm)
70
80
90
100
Temperature(C)
400W
Non
8 mm
12 mm
16 mm
20 mm
Figure (8) Temperature
Distribution with 400w
0 20 40 60 80 100
Length (mm)
50
60
70
80
90
TEMPERATURE(C)
300W
Non
8 mm
12 mm
16 mm
20 mm
Figure (7) Temperature
Distribution with 300w
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15. Tikrit Journal of Eng. Sciences/Vol.15/No.2/June 2008, (63-78)
0 20 40 60 80 100
Length (mm)
100
120
140
160
180
Temperature(C)
900W
Non
8 mm
12 mm
16 mm
20 mm
Figure (13) Temperature
Distribution with 900w
0.00 4.00 8.00 12.00 16.00 20.00
Perforation diameter(mm)
0.60
0.80
1.00
RWF
Figure (14) The relation between
ratio of weight of perforated fin to
that of non perforated fin(RWF)
and perforation diameter.
0 20 40 60 80 100
Length (mm)
90
100
110
120
130
140
150
160
Temperature(C)
800
Non
8 mm
12 mm
16 mm
20 mm
Figure (12) Temperature
Distribution with 800w
0 20 40 60 80 100
Length (mm)
80
90
100
110
120
130
140
150
Temperature(C)
700W
Non
8 mm
12 mm
16 mm
20 mm
Figure (11) Temperature
Distribution with 700w
77