Request pdf extended surfaces fins fins are widely used in various engineering equipment for increasing heat transfer rate from a surface. Typically, the fin material has a high thermal conductivity. Use the link below to share a fulltext version of this article with your friends and colleagues. Extended surfaces fins are widely used in the engineering field for enhancement of heat transfer rate by increasing surface area with additional material attachment. By increasing the heat transfer coefficient for the surface. Heat transfer from extended surfaces fins, fin equation, fin. Fins are used in a large number of applications to increase the heat transfer from surfaces. Finned surfaces are manufactured by extruding, welding, or wrapping a thin metal sheet on a surface. T, and heat loss, q f, for uniform cross section table 3.
Extended surfaces in practice often consist of smallcross section solids that protrude from the main body, such as fins attached to the walls of heat transfer equipment. Efficiency of extended surfaces with simultaneous heat and. Therefore, to increase the convective heat transfer, one can increase the temperature difference t st. In many applications like heat exchangers, for economizer, cooling reactor core. Fins are often seen in electrical appliance cooling such as in a computer power supply or substation transformers. Heat transfer with fins extended surfaces convection. Extended or finned surfaces heat exchangers buffalo. Fins are the extended surface protruding from a surface or body and they are meant for increasing the heat. Assuming that the fins have insulated tips, determine. By increasing the surface area in contact with air or providing fins. Sep 04, 2016 typical application areas of fins are heat transfer from extended surfaces fins aug. A study on temperature distribution, efficiency and. Heat transfer from extended surfaces fins, fin equation.
Pdf heat transfer from extended surfaces subject to variable heat. Fins are protrusions from the base surface into the cooling fluid, so that the extra surface of the. Heat transfer from finned surfaces the rate of heat transfer from a surface. Extended surfaces may exist in many situations but are commonly used as fins to enhance heat transfer by increasing the surface area available for they are particularly beneficial when h is small, convection andor radiation. Therefore, to increase the convective heat transfer, one can increase the temperature difference t st between the surface and the fluid. Multidimensional heat transfer in fins and fin assemblies pages. Fins are the extended surfaces designed to increase heat transfer rate for a fixed surface temperature, or lower surface temperature for a fixed heat transfer rate.
Fins and extended surfaces heat transfer applications for. Fins as extended surfaces a fin is a thin component or appendage attached to a larger body or structure in the context of heat transfer also, these are components protruding out of a heated or cold surface hot surface fin 3. Typical application areas of fins are heat transfer from extended surfaces fins aug. We also assume the convection heat transfer coefficient h to be constant and uniform over the entire surface of the fin for convenience in the analysis. Car radiators, back of fridges, motorcycle air cooled engines are all examples of enhancing heat transfer to a gas. Heat transfer between a solid surface and a moving fluid is governed by the newtons cooling law. By increasing the temp of the hot surface or by increasing the temperature difference between hot and cold bodies.
Pdf heat transfer from extended surfaces subject to. The analytical and experimental progress made in understanding the process of condensation on extended surfaces fins. Ppt extended surfaces fins powerpoint presentation free. Experimental study of extended surfaces fins with forced convection. This type of extended surface heat exchanger has corrugated fins mostly of triangular or rectangular crosssections sandwiched between the parallel plates. Extended surface, heat transfer, pin fin, thermal simulations i. Fins can be of a variety of geometryplain, wavy or interruptedand can be attached to the inside, outside or to both sides of circular, flat or oval tubes, or parting sheets. Kraus, phd, is professor of mechanical engineering at the university of akron, ohio, and is principal associate at allan d. Extended surfaces fins extended surfaces fins an extended surface also known as a combined conduction convection system or a fin is a solid within which heat transfer by conduction is assumed to be one dimensional, while heat is also transferred by convection andor radiation from the surface in a. Governing equation for temperature distribution in a fin 3. View extended surfaces fins research papers on academia.
Heeaat na andd mmass ttrraannssffeerr chaapptt eerr33. Experimental study of extended surfaces fins with forced. Sep 24, 2016 extended surfaces fins fin shapes and arrangements fins of uniform crosssection thermometer well fin effectiveness fin efficiency biot number finned wall triangular trapezoidal and annular fins efficiency plots. Pdf effect of condensation on performance and design of. 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 fluid by increasing heat transfer area. Heat transfer from extended surfaces or fins slideshare. Biggs ashra e member abstract an algorithm is presented to determine the efficiency of extended surfaces circular or longitudinal fins with a uniform thickness when simultaneous heat and mass transfer occur. The alternative is to increase the surface area by attaching to the surface extended surfaces called fins made of highly conductive materials such as aluminum. A fin with a cylindrical shape and a high aspect ratio lengthdiameter is called a pin. Fins as extended surfaces a fin is a thin component or appendage attached to a larger body or structure in the context of heat transfer also, these are components protruding out of a heated or cold surface. View table of contents for extended surface heat transfer. Enhancement of heat exchanger performance by the extended.
Efficiency of extended surfaces with simultaneous heat and mass transfer a. Extended surfaces have fins attached to the primary surface on one side of a twofluid or a multifluid heat exchanger. Extended surfaces thermal management of microelectronic. We also assume the convection heat transfer coefficient h to be constant. Fins or extended surfaces fins or extended surfaces are used to increase the heat transfer rate from surfaces whic h are con v ectiv ely co oled b y gases air under natural or forced con ection. 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. 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. In any heat exchanger form, the heat is transferred. The concept of fin efficiency for dry fins is outlined and that for wet surface conditions determined using a similar approach. Fins enhance heat transfer from a surface by exposing a larger surface area to convection and radiation. Extending the surface of a body in contact with a fluid can enhance heat transfer in convection. Extended surfaces fins extended surfaces fins are used to increase the heat transfer surface when you have significantly different heat transfer coefficients of the fluids exchanging heat. Heat exchanger, heat transfer surfaces, extended surface, fins.
Extended surfaces fins the normal textbook treatment of heat transfer from fins involves the solution by analytical means of an ordinary differential equation describing transport by conduction along the fin and convection from its surface. Sep 29, 2016 comparison of the different types of extended surfaces using heat transferpressure drop as the figure of merit. The cylinder is provided with 12 longitudinal straight fins of 0. Radiators for automobiles aircooling of cylinder heads of internal combustion engines e. Extended surface heat transfer in heat exchangers and. In this video lecture, we discuss heat transfer from extended surfaces using the fin equation.
Heat transfer between a solid surface and a moving fluid is governed by the. Heat transfer for fins or extended surfaces handout. Important parameters which affect the heat transfer from surfaces 2. Heat transfer surfaces operating in cold regions often involve condensation. Pprroobblleemmss ooff pprraaccttiicceess ooff hheeaatt. Types of fins heat transfer equation for fins introduction of fins. This discourse discusses the use of extended surface heat transfer in heat exchangers. The amount of conduction, convection, or radiation of an object determines the amount of heat it transfers. Fins of the circular, square and rectangular surfaces that extended from a pin.
Mar 20, 2020 finnedsurface application extended or finned surfaces are often used when one film coefficient is substantially lower than the other, the goal being to make hoaoe htat. Fins enhance heat transfer from a surface by exposing. Extended surfaces 5 extended surfacesfins extended. Heat transfer from extended surfaces subject to variable heat transfer coefficient article pdf available in heat and mass transfer 392. Longitudinal fins are used in doublepipe exchangers. Chapter 6 heat transfer from extended surfaces fins 6. 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. Heat transfer for fins or extended surfaces handout table 3. Sep 02, 2017 in this video lecture, we discuss heat transfer from extended surfaces using the fin equation. The size and cost of an exchanger is dependent upon the heat duty, the allowable pressure drop, and the geometry of the heat transfer area. In the study of heat transfer, fins are surfaces that extend from an object to increase the rate of. The thermal conductivity of cylinder and fin material is 75 wmk. The present article investigates the effect of locally variable heat transfer coefficient on the performance of extended surfaces fins subject to natural convection.
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