GANDHINAGAR INSTITUTE OF TECHNOLOGY SUBJECT : Heat Transfer TOPIC : Extended Surfaces-Fins Guided by :- Prof. Abhishek Swarnkar Prepared By :- Bhatia Simranjeetsingh B. (130120119017) Babar Prashant (130120119009) Ashutosh Kumar (130120119010)

Fin 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 (and/or radiation). Some typical fin configurations:

Extended Surface Analysis Tb P: the fin perimeter Ac: the fin cross-sectional area x

Extended Surface Analysis(Cont.)

The Fin Equation Assuming one-dimensional, steady-state conduction in an extended surface of constant conductivity and uniform cross-sectional area, with negligible generation and radiation , the fin equation is of the form: or, with and the reduced temperature , The general solution of linear homogeneous second order differential equation is of the form :

Heat dissipation from an infinitely long fin Temperature at the base of fin=Temperature of the surface to which the fin is attached at x=0 Temperature at the end of an infinitely long fin=surroundings. at x= So estimate heat flow rate is given by,

Heat dissipation from a fin insulated at the tip For this boundary conditions are: at x=0 So net heat transfer is given by: at x=0

Heat dissipation from a fin losing heat at the tip The relevant boundary conditions are: The fin is losing heat at the tip i.e. the heat conducted to the fin at x=l equals the heat convected from the end to the surroundings so, at x=0

Performance of fin It is ratio of actual heat transfer by fin to maximum heat is transfer where surface temperature is base temperature. [for infinitely long fin] [for insulated tip]

Effectiveness of the fin It is the ratio of the fin heat transfer rate to the heat transfer rate that would exist without a fin.

FIN EFFECTIVENESS The fin effectiveness can be increased by Increasing the thermal conductivity of material(k). Decreasing the value of convective heat transfer co-efficient(h) . By increasing the ratio of parameter to cross section area of the fins (P/A). By extending the length of fin but in an optimum value.

Temperature distribution Convection heat transfer Cases Tip condition (x=L) Temperature distribution Fin heat transfer rate A Convection heat transfer B Adiabatic C Constant Temperature D Infinite Fin Length

REAL IMAGES OF FINS

References https://en.wikipedia.org/wiki/Fin_(extended_surfa ce) https://www.google.co.in/?gws_rd=ssl#q=ppt+heat +transfer+in+rectangular+fin https://www.eng.fsu.edu/~shih/eml3016/lecture- notes/fin-design.ppt Heat and mass transfer by Dr. D.S.Kumar