pin fin

Jadavpur University,Saltlake CampusHeat Transfer Laboratory

Presentation on Heat Transfer From A Pin FinName Roll No

Souvik Mondal 06 Kaushik Halder 07

Branch:-Power Engg. , 3rd Year

TITLE :- Heat Transfer From A Pin Fin OBJECT:- (1) To study the temperature distribution along the length of a pin fin under forced convection with tip insulated. (2) To find out the heat transfer co- efficient of the pin fin & pin fin effectiveness.

What is heat transfer ?Heat Transfer is the exchange of thermal energy due to temp diff.This is of mainly 3 types->Conduction is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient. Conduction means collisional and diff usive transfer of kinetic energy of particles of matter. Conduction takes place in all forms of matter, i.e. solids, liquids, gases. Heat tends to flow from a higher temperature body to a lower temperature body.

Convection is the movement of molecules within fluids i.e. liquids, gases.It cannot take place in solids, as neither bulk current flows nor significant diff usion can take place in solids.Convection is one of the major modes of heat transfer and mass transfer. In the context of heat and mass transfer,Convection is used to refer to the sum of Advective and Diff usive transfer.

Radiation is energy emitted by matter as Electromagnetic waves due to the storage of thermal energy that all matter possesses that has a temperature above absolute zero. Thermal radiation propagates through the vacuum of space.

Convection is of two types – (i) Natural Convection & (ii) Forced Convection

Natural convection is a type of heat transfer, in which the fluid motion is not generated by any external source (i.e. a pump, fan, blower etc.) but only by density differences in the fluid occurring due to temperature gradients.

Forced Convection is a type of heat transfer,in which the fluid movement results from external surface forces such as a fan or pump or blower. Forced convection is typically used to increase the rate of heat exchange. Many types of mixing also utilize forced convection to distribute one substance within another.

Application of extended surfaces in Convection:- For both modes of convection heat transfer i.e. Natural &Forced Convection,extended surface known as Fin, is used to increase the rate of heat transfer from a surface to a fluid where heat transfer coeffi cient of the surface and temp. diff. between them is not possible to increase.

How Fin increases the heat transfer rate? Fin increases the surface area available for heat transfer.

Wide application of fins:- Fins are vastly used on the radiator surface,on the boiler water tubes,heat exchanger tubes & sometimes on Electronic equipments.

APPLICATION OF PIN FIN IN PRACTICAL LIFE

pin fin heat sink is used to cool the processer .

The Front view of the experimental setupwhere Heat Transfer From Pin Fin experiment was done.

VoltmeterReadings

AmmeterReadings

TemperatureReadings

DeliveryPipe

Heater

Pump

Rectangular DuctWith Pin Fin

inside it

Manometer

Open Rectangular Channel of the device from where the air is sucked

PinFin Temperature

Point

One Side Opened Rectangular Duct With A Circular Pin Fin At The Center

12 mm

100 mm

150 mm

15mm 15mm30mm 30mm 30mm 30mm

Air is sucked inside

Pin fin

Hot Air

Air Flow Direction is shown here Through the Rectangular Duct

Assumptions:-(i) Steady state Heat Conduction.(ii) Pin Fin Tip insulated i.e. no heat convection from the pin fin tip.

(iii) The shape of pinfin is cylindrical so that perfect fluid and thermal boundary layer can construct.

No Heat Convection

Boundary layer over cylinder

Mathematical Formulae we used for calculation:-

T-Tf =

Where,

m=qfin=

Where,

.

q=(Ts-Tf)(hPAk) tanh mL & qideal=hPL(Ts-Tf)

Ts-Tf

Cosh m(L-x)

Cosh mL

hPkA.

qq

ideal

I

Sl No

HeaterVoltage (V)

HeaterCurrent (Amp)

Manometer readingCm of H2O

Steady

T1

(.c)

State

T2

(.c)

Pin

T3

(.c)

Fin

T4

(.c)

Temp.T5

(.c)

FluidAmbientTemp. T6

(.c)

1. 40 0.17 1.6 74 64 56 51 48 33 2. 60 0.26 1.6 96 82 69 61 56 34 3. 70 0.30 1.6 102 86 72 64 58 34

Observation Table:-

Specifications:-

(i)Width=150 mm, Breadth=100 mm

(ii) Diameter of the Fin=12 mm

(iii) Diameter of the Orifice=20 mm

(iv) Diameter of the Delivery Pipe=40 mm

(v) Length of Fin=150 mm

(vi) Co-efficient of Discharge=0.61

Sample Calculation:-• Volume Flow Rate of Air,Q=Cd A1A2 2g[w/a-1]

A12-A2

2

or,Q=3.199*10-3 m3/sec• Velocity of Flowing Air,V=Q/a=0.242 m/sec

• Reynolds number,Re=VD/=176.322

• Value of Nusselt number using Correlation,Nu=0.683Re0.466Pr1/3

=6.76

now, T-Tf = Cosh m(L-x)

Ts-Tf Cosh mL

let,

Ts=T1, T=T2 & Tf=T6 we get the value of m through iteration

technique,m=10.85

• Theoritical Temperatures are, T2-33

= Cosh 10.85(0.135-0.03)

74-33 Cosh (10.85*0.135)Or,T2= 63.98 .c

Thus the Other Temperatures are, T3= 57.285 .c

T4= 53.179 .c

T5= 51.23 .c

• Fin Effectiveness, qeff= qfin

qwithout fin

= (Ts-Tf)(hPAk) tanh mL

hA(Ts-Tf)

= 27.61

0 20 40 60 80 100 120 140 1600

10

20

30

40

50

60

70

80

Experimental TemperaturesTheoritical Temper-atures

Length of Fin(mm)

Tem

pera

ture

s(. c)

Acknowledgement:-We are sincerely thankful to our teachers->

(i) Prof. Apurba K. Santra

(ii) Prof. Amitava Dutta

(iii) Sri Atish Nandi

(iv) Sri Biraswar paul (v) Sri Prakas Ghosh.

Thank You

Good Afternoon