experimental work by fins

1. Presented to :-
Prof K. M. Pandey
Presented by:-
PRASANT(18-22-114)
HEAT TRANSFER
THROUGH FINS

2. Contents
• Introduction
• working principle
• Method of increase heat transfer
• Type of design
• Type of fins
 straight fin
 annular fin
 trapazoidal fin
• Advantage
• Disadvantage
• Application
• Fin performance
• Result and discussion
 heat transfer performance
 Effect of flowrate
• Conclusion

3. Introduction
• Fins are generally used to enhance the heat transfer from a
given surface
• Addition of fins can increase the heat transfer from the
surface by several folds
• In many engineering situation, means are often sought to
improve heat dissipation from a surface to its surrounding
• Whenever the available surface is found inadequate transfer
the required quantity of heat with available temperature
drop and convective heat transfer coefficient, extended
surfaces or fins are used.
• By increasing the surface area in contact with air or
providing fins
• By increasing the heat transfer coefficient the surface
• By increasing the temperature difference between hot and
cold bodies

4. WORKING PRINCIPLE
• In many engineering application, large quantities of
heat have to be dissipated from small areas.
• The fins increases the effective area of the surface
thereby increasing the heat transfer by convection.
• In other words, the shape of fins must be optimized
such that the heat transfer density is maximized
when the space and the materials used for the
finned surfaces are constraints.

5. METHODS TO INCREASE HEAT
TRANSFER RATE
• By increasing the surface area in contact with air or
providing fins.
• By increasing the heat transfer coefficient for the
surface.
• By increasing the temp of the hot surface or by
increasing the temperature difference between hot
and cold bodies

6. TYPES BY DESIGN
• The fins are designed and manufactured in
many shapes and forms.
• They manufactured in different geometries,
depending upon the practical applications.
• The ribs attached along the length of a tubes are
called longitudinal fins.
• The concentric annular disc around a tube are
termed as circular or annular fins
• Pin fins or spines are rods protrading from a
surface.

7. TYPES OF FINS

8. Straight Fins
A straight fin is any extended surface that is attach
to plane wall it may be uniform cross sectional area or
its cross sectional area varies with the distance x from
the wall

9. Annular Fins
An annular fin is one that is circumferentially
attached to the cylinder and its cross section
varies with radius from the wall of the cylinder.

10. Trapezoidal Fins
Heat transfer by convection between a surface and
the fluid surrounding can be increased by
attaching to the surface thin metallic strips.

11. ADVANTAGES
• By using the fins, heat transfer rate can be
increased without any preventive
maintenance.
• It is the cheapest way for increasing the heat
transferring rate from the hot bodies.

12. DISADVANTAGES
• We know that the length of fins is directly
proportional to the heat transferring rate. But
the larger length is may be cause of bending in
the fins and also increases the weight of
engine. Therefore the overall efficiency will
goes to decrease.
• Weknow that the length of finsisdirectly
proportional to the heat transferring rate. But
the larger length ismay be causeof bending in
thefins

13. APPLICATIONS
• Common applications of finned surfaces are with
cooling of electronics components
• Condensers and economizers of thermal power
plants
• Radiators for automobiles
• Dry type cooling towers
• Air cooled cylinders of compressors, IC engines
• Evaporators and condensers of refrigeration and
air conditioning system.
• Electric motor and transformers

14. Fin performance can be described in three different ways.
1:- Thefirst is fin effectiveness. It is the ratio of the fin heat transfer rate to
the heat transfer rate of the object if ithad no fin. The formula for this is
where is the fin cross-
sectional area at the base
2:- Fin performance can also be characterized by fin efficiency. This is the
ratio of the fin heat transfer rate to the heat transfer rate of the fin if the
entire fin were at the base temperature.
in this equation is equal to the surface area of the fin
Fin efficiency will always be less than one

15. 3:- Thethird wayfin performance can be described is with overall surface
efficiency.
is the total area and is the sum of the heat transfer rates of allwhere
the fins.

16. comparison of the different types of extended
surfaces using heat transfer/pressure drop as the
figure of merit.

17. Shows that, from a purely size standpoint, pin fins
offer the smallest design for the best heat transfer
while straight fins are the most inefficient from a heat
transfer and smallest size constraint.

18. Results and Discussion
Heat Transfer Performance
The heat transfer performance of the heat exchanger was evaluated
in terms of dimensionless parameter Nusselt number. The main
purpose was to test the effects of geometric (tube
arrangement, fin shape and tube inclination angle) and flow
parameters on the heat transfer performance of compact flat tube-
and-fin heat exchanger.

19. Effects of flowrate
Shows variation of Nusselt number for plain fins against
Reynolds number for inline configuration. The presented result
shows that as the flow rate increases so does the Nusselt
number. Moreover, it shows that the Nusselt number is directly
proportional to the flowrate. This means the increase in the air
velocity yields increment in the convection heat transfer of the
heat exchanger. Results with similar trend has been seen from
the simulation work The increasing trend is seen due to the
better mixing of flow.

20. Conclusion
From this study, it was found that the rectangular fin has the highest heat
transfer performance compared to wavy and plain fin where wavy fin is higher
than plain fin. Rectangular fin produces the highest heat transfer performances
due to the interruption done by the staggered surfaces to the flow and
temperature boundary layers along the flow orientation. The hydraulic
performance has the similar trend where rectangular has the highest pressure
drop compared to wavy and plain fin. This is due the interruption that wavy
and rectangular fin geometry does to the flow of air. The pressure drop of plain
fin is low compared to complex design of wavy and rectangular fin. Wavy and
rectangular fin despite having higher heat transfer performance, they have a
greater drawback in higher pressure drop. On the other hand, rectangular fin is
suited for any application which prioritises thermal performance over hydraulic
performance or efficiency.

21. THANK YOU