We now wish to establish the differential equation relating temperature in the fin as a function of the radial coordinate r. Types of fins, fin applications, heat transfer through fin of uniform crosssection. Straight fins of a uniform and b nonuniform cross sections. Heat transfer enhancement by heat sink fin arrangement in. The fin is exposed to a flowing fluid, which cools or heats it, with the high thermal conductivity allowing increased heat being conducted from the wall through. The airside heat transfer coefficient is calculated from the measured data. This increase of total tube surface allows transfer of a greater amount of heat from hot gas, but the demand for smaller installation sizes requires smaller fin pitch with larger fin height. Adding a fin to an object increases the surface area and can sometimes be an economical solution to heat transfer problems. In the analysis of fins, we consider steady operation with no heat genera tion in the fin, and we assume the thermal conductivity k of the material to remain. Steady heat transfer through a twodimensional rectangular. Evaluation of fin efficiency and heat transfer coefficient. Heat transfer between a solid surface and a moving fluid is governed by the newtons cooling law. We also learned that as molecules heat up and move faster, they spread apart and objects expand get bigger. Typically, the fin material has a high thermal conductivity.
For a constant heat transfer coefficient over the fin. Fins are used on all air coolers, dry coolers, evaporators. Air cooled engines have fins to radiate heat to surrounding air. A typical schematic of a single circular fin on a pipe is shown in the figure below. Pdf effects of fin per inch on heat transfer and pressure. Which of the following is correct fins should be attached on the side where the heat transfer coefficient are high effectiveness of fins depends on thermal conductivity only fins must have small thickness for better heat dissipation in boiling heat transfer appliances, fins will be very effective 2.
On the one hand, the heattransferring surface can be enlarged by an arrangement of annular fins or other elements. The slides were prepared while teaching heat transfer course to the m. Efficiency can be found directly from the efficiency chart if we know the corrected. Use of perforated fins as a natural convection heat transfer. Fins or extended surfaces microelectronics heat transfer. Review of literature on heat transfer enhancement in. Preface this file contains slides on heat transfer from extended surfaces fins. Fins enhance heat transfer from a surface by exposing a larger surface area to convection and radiation. In many applications like heat exchangers, for economizer, cooling reactor core.
Heat transfer by convection between a surface and the fluid surrounding it can be increased by attaching to the surface thin strip of metal called fins. Extended surfaces fins are widely used in the engineering field for enhancement of heat transfer rate by increasing surface area with additional material attachment. General governing equation for heat transfer from a finned surface is expressed as. In the study of heat transfer, fins are surfaces that extend from an object to increase the rate of heat transfer to or from the environment by increasing convection. Application of bessel equation heat transfer in a circular fin. Types of fins a rectangular plate fins b tapered fin c. Effects of fin per inch on heat transfer and pressure drop of an air cooler with circular and hexagonal fins article pdf available in life science journal 101. Various methods for steadystate and transient analysis of temperature distribution and efficiency of continuousplate fins are presented. Curves the basic performance data for an enhanced surface are often shown as curves of the colburn factor j stpr2f3, and the fanning friction factor t, plotted versus reynolds number. Hear transfer from extended surfaces fins duration.
Heat and mass transfer ii me315 chapter 3 heat transfer from extended surfaces. Heat transfer processes set limits to the performance of aerospace components and systems and the subject is one of an enormous range of application. Molecules with more heat energy move faster, and molecules with less heat energy move slower. Ic engine the radiator which is cross flow type heat exchanger to release the heat in to surrounding to maintain the engine at favorable temperature. Fins ppt radiator heat transfer free 30day trial scribd. Q chapter 10 429 and therefore r total r plastic r conv 0. Fins are generally used where convection heat transfer coefficient h values are relatively low i.
Pin fins are used to increase the heat transfer rate from surface to the surrounding fluid when h value is generally smaller on the surface. The heat transfer from surfaces may in general enhanced by increasing the heat transfer coefficient between a surface and its surroundings, by increasing the heat transfer area of the surface. Heat transfer in fins wolfram demonstrations project. Heat transfer california state university, northridge. Joseph engineering college, vamanjoor, mangalore, india, during sept. Heat transfer from extended surfaces fins, fin equation, fin effectiveness, and fin efficiency duration. Phlogiston press, c2003 includes bibliographic references and index. To do this, consider an element, of the fin as shown in figure 18.
The fin is exposed to a flowing fluid, which cools or heats it, with the high thermal conductivity allowing increased heat being conducted from the wall through the fin. Heat transfer through fins study notes for mechanical. The governing equation comes from an energy balance on a differential ring element of the fin as shown in the figure below. The graph if figure 3 clearly shows that the heat transfer coefficient decreases as the gap between fins decreases. Fins are used on all air coolers, dry coolers, evaporators and condensers that transfer energy from a primary coolant or liquid media to air, although in some situations the air may be so unclean that there is a risk of blockage. Alternatively, the rate of heat transfer from the fin. Analysis in the case of no fins, heat transfer from the tube per meter of its length is determined from newtons law of cooling to be effect of fins on heat transfer from steam pipes. Fins are extensions on exterior surfaces of objects that increase the rate of heat transfer to or from the object by increasing convection. Introduction and background heat transfer theory provides a direct means of developing engineering estimates of the rate of heat transfer in various practical situations.
Pdf heat transfer through fins of complex geometry researchgate. Scholar department of mechanical engineering btkit dwarahat abstractextended surfaces are used to increase heat transfer rate and this study related to extended surfaces fin and heat transfer rate. Staggered fin and tube alignments improve heat transfer performance by 7% and 10%, respectively, as compared to. Effect of different fin geometries on heat transfer coefficient mr. Heat transfer simulation by cfd from fins of an air cooled motorcycle engine under varying climatic conditions pulkit agarwal, mayur shrikhande and p. Heat transfer from surfaces with uniform crosssections solutions based on various boundary conditions, fin efficiency curves applications and design need for fins the rate of heat transfer from a surface at a temperature ts to the surrounding medium at t is given by newtons law of cooling as. Increasing the temperature gradient between the object and the. Fins are used in a large number of applications to increase the heat transfer from surfaces. Effects of fin and tube alignment on the heat transfer. Experimental investigation of heat transfer by pin fin. Introduction to engineering heat transfer these notes provide an introduction to engineering heat transfer. Near about ranging 5% to % more heat transfer can be achieved with these various extensions on fin as compare to same geometry of fin without these extensions. Investigation of heat transfer rate and temperature.
There is heat flow of magnitude at the lefthand side and heat flow out of magnitude at the right hand side. The development of technology with increase heat transfer coefficient rate stimulated extensive research throughout the world leading to the use increasing of heat flux and heat transfer areas. The heat transfer coefficient of air is calculated using nusselt correlations for laminar flow over a flat plate and a cylinder. Use of perforated fins as a natural convection heat. Air flows laminarly across the fin in the direction indicted by the arrows in the figure rotate the fin with a mouse to help visualize the flow pattern. Heat transfer l9 p1 fin efficiency and corrected length duration. In thermodynamics, we considered the amount of heat transfer as a system. Heat transfer simulation by cfd from fins of an air cooled. This research presents the results of numerical study of heat transfer and pressure drop in a heat exchanger that is designed with different shape pin fins. In your surroundings you observe many heat transfer applications day by day ex.
Extended surfaces may exist in many situations but are commonly used as fins to enhance heat transfer by increasing the surface area available for convection andor radiation. Fins are extended surfaces used to increase the heat transfer rate between a hot body and. Effect of different fin geometries on heat transfer. Generally the area of heat transfer is increased by utilizing the extended surfaces in the form of. A fin is a surface that extends from an object to increase the rate of heat transfer to or from the environment by increase convection. We also assume the convection heat transfer coefficient h to be constant. Fins are the extended surface protruding from a surface or body and they are meant for increasing the heat transfer rate between the surface and the surrounding. Sep 07, 2017 heat transfer from extended surfaces fins, fin equation, fin effectiveness, and fin efficiency duration.
If there is little variation in temperature across the fin, an appropriate model is to say that the temperature within the fin is a function of only, and use a quasionedimensional approach. Adding a fin to an object, increases the surface area resulting in an effective heat transfer. A convenient definition of heat transfer is energy in transition due to temperature differences. Properties the thermal conductivity of the fins is given to be k 180 wm c. For a constant heat transfer coefficient over the fin surface, the plate fin can be divided into imaginary rectangular or hexangular fins. If the fins are closely spaced, the heat transfer coefficient h is lower because mixing of the boundary layer occurs the fills up with warm air. Finned surfaces are commonly used in practice to enhance heat transfer, and they often increase the rate of heat transfer from a surface severalfold. Common assumptions for fins finned surfaces are commonly used in practice to enhance heat transfer in the analysis of fins, we consider steady operation with no heat generation in the fin, and we assume the thermal conductivity k of the material to remain constant. Convection, exponential, biot number, fin, heat transfer.
The basic requirement for heat transfer is the presence of a temperature difference. The fin provides heat to transfer from the pipe to a constant ambient air temperature t. Teacher slides extended surface heat transfer nptel. Heat transfer extends the thermodynamic analysis by studying the fundamental processes and modes of heat transfer through the development of relations used to calculate its rate. The steady heat transfer in a heatgenerating fin with simultaneous surface convection and radiation is studied analytically using optimal homotopy asymptotic method oham. The steady response of the fin depends on the convectionconduction parameter, radiationconduction parameter, heat generation parameter, and dimensionless sink temperature. This is achieved by increasing the surface area of the body, which in turn increases the heat transfer rate by a sufficient degree. Fin act as insulation if thermal conductivity k of fin material is low. Oct 03, 2014 the amount of conduction, convection, or radiation of an object determines the amount of heat it transfers. Following the definition of heat, there are only two physical mechanisms for heat transfer. Fin convection experiment the purpose of this experiment is to determine the convective heat transfer coefficients for free and forced convection over a fin. Generally the area of heat transfer is increased by utilizing the extended surfaces in the form of fins attached to base of the plate.
A fin is a part of a machine or equipment that is having sole purpose to increase the surface area so that the heat transfer increase usually between air and a heat generating device like engine, cpu, heat exchanger etc. Chapter 3 fins heat transfer thermal conduction scribd. A heat exchanger includes a fin body and a heat pipe having a first portion disposed on or at least partially within the fin body and a second portion extending from the fin body, wherein the heat pipe includes a hollow core filled with a heat pipe working fluid having a liquid phase that is configured to transition to gas and to be returned to the liquid phase at an operational temperature of. Conduction, convection, and radiation introduction we have learned that heat is the energy that makes molecules move. Cylinder is made of cast iron and fins are made of stainless steel. Design and analysis for heat transfer through fin with.
Series solution for steady heat transfer in a heat. The steady rate of heat transfer from the entire fin can be determined from fouriers law of heat conduction very long fin. Natural convective heat transfer from interrupted rectangular. This demonstration calculates the heat transfer rate through a single fin either a rectangular or a pin fin mounted on a heat sink at 500 k. Fins of same thickness with more than one materials rather than the coatings are considered for the steady state thermal analysis is made on those fins and comparison of heat transfer rate is made between the fins of same material and fins and fins of composite material when in bonded contact. Fin, finite length fin heat transfer analysis duration. Rate of heat transfer from fin at base or root is expressed as. Heat transfer and pressure drop performance comparison of. Finned surfaces are commonly used in practice to enhance heat transfer. Srinivasan proceedings of the world congress on engineering 2011 vol iii wce 2011, july 6 8, 2011, london, u. Fin with various extensions design with the help of software autocad. The heat transfer performance of fin with same geometry having various extensions and without extensions is compared.
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