THERMAL CONDUCTIVITY OF METAL ROD - PESIT Southpesitsouth.pes.edu/pdf/2017/mechanical/HMT LAB MANUAL.pdf · PES IT - BSC [ HEAT TRANSFER LAB] Department Of Mechanical Engineering

PES IT - BSC [ HEAT TRANSFER LAB]

Department Of Mechanical Engineering Page 1

EXPERIMENT NO. 1

THERMAL CONDUCTIVITY OF METAL ROD

AIM: To determine the thermal conductivity of given metal rod

APPARATUS: Experimental setup of metal rod

THEORY: Write the theory on following points

1. Definition of Heat transfer, applications, three modes of heat transfer with their

governing laws, definition of thermal conductivity, thermal conductivity of important

materials

2. Terms in three dimensional heat transfer equation and definition of thermal

diffusivity

3. Variation of thermal conductivity with temperature in solids, liquids and gases

DESCRIPTION OF THE APPARATUS:The apparatus consists of the aluminum rod of 200mm test section. Heat is provided

by means of band heater at one end and released through water jacket arrangement at

another end. Thermocouples are provided at suitable points to measure the surface and water

temperatures. Proper insulation is provided to minimize the heat loss in radial direction. The

temperature is shown by means of the digital indicator on the control panel, which also

consists of heater regulator and other accessories with instrumentation having good

aesthetic looks and safe design.

PROCEDURE:1. Give necessary electrical and water connections to the instrument.

2. Switch on the MCB and console ON to activate the control panel.

3. Set the voltage in the range of 70-80 volts

4. Start the cooling water supply through the water jacket (make sure it should not to

exceed 3 lpm).

5. Note the temperature at different points, when steady state is reached.

6. Repeat the experiment for different heater input.

7. After the experiment is over, bring the voltage to minimum, switch off the heater and

then main, allow the water to flow for some time in the water jacket and then stop it.

SPECIFICATIONS:1. Type of Material =Aluminium

2. Diameter of the metal rod=50mm



3. Test length of the metal rod=200mm

4. Distance between two consecutive thermocouples=50mm

5. Distance between First end and first thermocouple, last thermocouple and last

end=25mm

6. Thermocouple type-K type (Cr-Al)

7. Maximum voltage and current range=150 volts

PRECAUTIONS:

1. Do not give heater input without the supply of water.

2. Input should be given very slowly.

3. Run the water in the jacket for about 5 min after the experiment.

4. Do not run the equipment if the voltage is below 180V.

5. Check all the electrical connections before running.

6. Before starting and after finishing the experiment the heater controller should be in

Off position.

7. Do not attempt to alter the equipment as this may cause damage to the whole

system.

TABULAR COLUMN:

Sl.No.

Rlpm

T1oC

T2oC

T3oC

T4oC

T5oC

T6oC

QW

KW/mK

1

2

3

Where

R= Rotameter reading, lpm

T1 to T4 =Temperatures on metal rod at different locations, oCT5 and T6= Inlet and outlet temperatures of cooling water, oC

Q= Heat transfer from the rod, W=mw=mass flow rate of water, kg/s

= ρw x R/60

ρw= Density of water=1000 kg/m3



Cpw= Specific heat of water=4.2 x 103J/kg/K

dT=Temperature difference of cooling water, K or oC

= T6-T5

Q= Thermal conductivity of metal rod, W/mK= −A= Cross sectional area of metal rod, m2

A =4

2d

d= Diameter of the metal rod, m

dT/dX = Slope obtained from the graph of Temperature v/s Length of the metal

rod, oC/m

dT/dX is negative. To make Q positive in +X direction, K relation has to be

multiplied by negative sign

K = Thermal conductivity of metal rod, W/mK

GRAPHS: T v/s L (Length of the metal rod)

RESULTS:Thermal Conductivity of metal rod is found to be _______________ W/mK.

EXPERIMENTAL SETUP OF THERMAL CONDUCTIVITY OF METAL ROD

EXPERIMENT NO. 2



HEAT TRANSFER THROUGH COMPOSITE WALL

AIM: To determine the overall heat transfer coefficient (neglecting the convective resistance)of a composite wall.

APPARATUS: Composite wall setup

THEORY: Write the following theory topics

1. Definition of composite wall

2. Application of composite wall

3. Definition & Significance of overall heat transfer coefficient

4. Electrical analogy for composite wall arranged in series and parallel

5. Thermal resistance and thermal contact resistance

DESCRIPTION OF THE APPARATUS:

The apparatus consists of three slabs of Bakelite, mild steel and Aluminum materials of

thickness 15, 20 & 25mm respectively clamped in the center using screw rod. At the center

of the composite wall a heater is fitted. End losses from the composite wall are minimized by

providing thick insulation all rounds to ensure unidirectional heat flow. Front transparentacrylic enclosure to minimize the disturbances of the surrounding and also for safety of the

tube when not in use.

Control panel instrumentation consists of: Digital Temperature Indicator with channel

selector. Digital Voltmeter & Ammeter for power measurement. Heater regulator to

regulate the input power. With this the whole arrangement is mounted on an aesthetically

designed self-sustained MS powder coated frame with a separate control panel.

PROCEDURE:

1. Symmetrically arrange the plates and ensure perfect contact between the plates.

2. Switch ON main and the CONSOLE.

3. Set the heater regulator to the known value.

4. Wait for sufficient time to allow temperature to reach steady values.

5. Note down the Temperatures 1 to 4 using the channel selector and digital temperature

indicator.

6. Note down the ammeter and voltmeter readings.

7. Repeat the experiment for different heat input.



SPECIFICATIONS:1. Number of layers=3

2. Material type= aluminium mild steel and bakelite

3. Thickness of each plate; aluminium= 25mm, mild steel=20mm, bakelite=15mm,

4. Diameter of plates= 20cm

5. Thermal conductivity of metal plates; aluminium= 204 W/mK mild steel =49WmK,

bakelite =1.4 W/mK,

6. Thermocouple type= K type (Cr-Al)

7. Maximum range of voltage =150volts

PRECAUTIONS:

1. Check all the electrical connections.


3. Do not attempt to alter the equipment as this may cause damage to the whole system.

TABULAR COLUMN:

Sl.No.

VV

IA

T10C

T20C

T30C

T40C

QW

Uexp

W/m2KUth

W/m2K

12

3

Where, V = Voltage supplied, volts

I= Current supplied, Amperes

T1, , Temperature aluminium plate, 0C

T2, = Temperature between aluminium and Bakelite, 0C

T3, = Temperature between Bakelite and mild steel plate, 0C

T4, = Temperature on exposed surface of mild steel plate, 0C

Q = Heat Transfer through composite wall, W



=Uexp= Experimental overall heat transfer coefficient, W/m2K

oi TTQU

Aexp

A= Area of composite wall normal to heat flow, m2=d= Diameter of composite wall, m

Uth= Theoretical Overall heat transfer coefficient, W/m2K

b

b

ms

ms

a

a

KL

KL

KL

1thU

La, Lms and Lb =The thickness of mild steel, bakelite and aluminium plates, m

Ka, Kms and Kb = The thermal conductivity of mild steel, bakelite and aluminium plates,

W/mKGRAPHS: Temperature distribution graph for the average temperature of each plate

RESULTS:

The overall heat transfer coefficient (neglecting the convective resistance) ofcomposite wall is _____________ W/m2 K. and its theoretical value is______________ W/m2 K

EXPERIMENTAL SETUP OF COMPOSITE WALL



EXPERIMENT NO. 3

PIN-FIN APPARATUS

AIM: To determine the effectiveness and efficiency of given pin-fin and draw temperature

distribution graph experimentally and theoretically under natural and forced convection

conditions

APPARATUS: Experimental setup of pin-fin apparatus


1. Definition of fin, functions of fin

2. Types of fins with neat sketches

3. Three conditions of fin with their temperature distribution and heat transfer

expressions.

4. Effectiveness and efficiency of fin

DESCRIPTION OF THE APPARATUS:The apparatus consists of Pin type fin of dia 12mm and 150 mm long made of aluminiumwith suitable temperature points.

Heater of 250 W capacity.

Heater regulator to supply the regulated power input to the heater.

Digital Voltmeter and Ammeter to measure power input to the heater.

Thermocouples at suitable position to measure the surface temperatures of the fin.

Digital Temperature Indicator with channel selector to measure the temperatures.

Blower unit to blow air through the duct with orifice meter and acrylic manometer to

measure the air flow rate from the blower. A control valve is provided to regulate the air

flow. Control panel to house all the instrumentation.

With this, the whole arrangement is mounted on an aesthetically designed self-sustained MS

powder coated frame with a separate control panel.

PROCEDURE:

1. Switch on the MCB and then console on switch to activate the control panel.

2. Switch on the heater and regulate the power input using the heater regulator.

3. Switch on the blower unit and adjust the flow of air using gate valve of blower to a

desired difference in manometer (for forced flow only otherwise skip to step 4).4. Wait for reasonable time to allow temperatures to reach steady state.

5. Measure the voltage, current and temperatures from T1 to T6 at steady state.



6. Calculate the effectiveness & efficiency of the fin using the procedure given.

7. Repeat the experiment for different values of power input to the heater and blower air

flow rates.

SPECIFICATIONS:1. Fin material= Aluminium

2. Length of the Fin=110mm

3. Fin diameter=12mm

4. Thermal conductivity of the fin=205 W/mK

5. Distance between two consecutive thermocouples on fin=20 mm, from heater end to

first thermocouple 20mm, from last thermocouple to fin end 10 mm


7. Diameter of orifice=20 mm

8. Diameter of pipe=50mm

9. Coefficient of discharge of orifice=0.62

10. Dimensions of the duct=145mm x 90mm

PRECAUTIONS:1. Check all the electrical connections.2. Do not run the equipment if the voltage is below 180V.

3. Do not obstruct flow of air while experiment is going on.

4. Do not turn the heater regulator to the maximum as soon as the equipment is started.


TABULAR COLUMN:Natural ConvectionSl.No.

Vvolts

IA

T10C

T20C

T30C

T40C

T50C

T60C

hthW/m2K

ε η%

1

2

3

Forced convection

Sl.No.

Vvolts

IA

T10C

T20C

T30C

T40C

T50C

T60C

T70C

Vmm/s

hW/ m2K

ε η%

1

2

3



Where

V, I are voltage and current supplied to the heater, Volts and Amperes

T1, to T5 = Temperatures on surface of the fin, 0C

T6= Ambient temperature in natural convection, 0C

T6, T7 = Temperatures of air at inlet and outlet under forced convection, 0C

hw= Manometer reading, m of water

vm = Mean velocity of air, m/s=Ad= Area of duct, m2

Ad= lxb

l and b are length and breadth of duct, m

ma= Mass of air circulated, kg/s

ma= ρ x Vp

ρ= Density of air, kg/m3

Vp= Actual volume flow rate of air through pipe, m3/s=Cd= Coefficient of discharge of orifice

Ao=Area of orifice, m2=do= Diameter of orifice, m

Ap=Pipe area, m2=Dp=Diameter of pipe, m

Ha= Head of air, m of air= ( − 1)ρw= Density of water, 1000kg/m3

Determination of hth for natural convection condition=Nu= Nusselt Number

NU = 1.1 (Gr.Pr)1/6 when 10-1<Gr Pr< 104



= 0.53 (Gr.Pr)0.25 when 104<Gr Pr<109

=0.13 (Gr.Pr)0.33 when 109<Gr Pr< 1012

Gr= Grashoff Number

= ( )lf= length of fin, m

β= Volumetric expansion coefficient, /K=Tmf=Mean film temperature, oC=Tavg= Average temperature of the fin, oC

=

T∞= Ambient temperature in case of natural convection, oC =T6

µ= Dynamic viscosity of air, Ns/m2

Pr= Prandtle Number

df= Diameter of the fin, m

ρ, µ, Kair, Pr for air are obtained from HMT data book at mean film temperature Tm

Determination of hth for forced convection condition== 0.023 × . .Re= Reynolds Number=Dh=Hydraulic diameter=4A/PA=Cross-sectional area of duct=lxb

P=Perimeter of the duct=2(l+b)

Tb=(T6+T7)/2=Bulk mean temperature, oC

C and n are obtained from HMT data book at Re

Properties of air such as ρ, µ, K, Pr are obtained from HMT data book atTb



Determination of Effectiveness and Efficiency of pin-finAssume fin with insulated end

ɛ= Effectiveness of fin=Qfin=Heat transfer rate with fin, W= ( − ) tanhP= Perimeter of the fin, m

=π df

K= Thermal conductivity of fin material, W/mK

A=Cross sectional area of fin m2

=m= constant=

Qwithout= Heat transfer rate without fin, W= ( − )To= Base temperature, oC= T1

η= Efficiency of the fin

= = ( )=

Theoretical Temperature distribution along the fin= ( )Tx= Temperature of the fin at the given distance x, oC

GRAPHS: Temperature v/s fin length (Experimentally and analytically)

RESULTS: Effectiveness and efficiency of given fin are _________ and _______



EXPERIMENTAL SETUP OF PIN-FIN APPARATUS



EXPERIMENT NO. 4

TRANSIENT HEAT CONDUCTION

AIM: To determine heat transfer coefficient and instantaneous heat transfer rate for transient

heat conduction and draw the graph of temperature variation with time

APPARATUS: Transient heat conduction expt. setup, oil/water, stopwatch

THEORY: Write the theory on following topics

1. Definition of transient heat conduction, types and applications

2. Methods of analyzing transient heat conduction with explanation

3. Significance of Biot and Fourier’s numbers

4. Definition of semi-infinite solids, applications

DESCRIPTION OF THE APPARATUS:The apparatus consists of a small tank in an electric heater is provided and is used for heating

of fluid. A spherical ball of 50mm diameter made by aluminium is used as testing object.

Two thermocouples are fixed to the sphere to measure its surface and core temperature. One

more thermocouple is placed inside the tank to measure fluid temperature. It also consists a

Heater regulator to supply the regulated power input to the heater and Digital TemperatureIndicator with channel selector to measure the temperatures.

Control panel to house all the instrumentation.With this, the whole arrangement is mounted

on an aesthetically designed self-sustained MS powder coated frame with a separate control

panel.

SPECIFICATIONS:1. Type of material=aluminium

2. Diameter of the sphere= 50mm

3. Type of fluid=water/oil, air

4. Thermal conductivity of sphere material=205W/mK

5. Thermal diffusivity of sphere material=84.18x10-6m2/s


PRECAUTIONS:1. Check all the electrical connections.







PROCEDURE:1. Take the fluid (water or oil) in the tank.

2. Heat the fluid to the required temperature say 70oC in case of water and more than

100 oC in case of oil.

3. Note down the initial temperature of sphere and hot fluid.

4. Immerse the sphere in hot fluid bath for heating.

5. Note down the core and outer surface temperature of the sphere at every 10 seconds

till it attains fluid temperature.

6. Take out the sphere from hot fluid and cool it in atmospheric air.

7. Note down the temperature at every 10 second till it reaches atmospheric condition.

8. Repeat the experiment for different temperatures of fluid.

TABULAR COLUMN:Initial temperature of fluid =

Initial temperature of sphere=

t

s

Tc

oC

To

oC

Where,



t= Time, seconds

Tc= Core Temperature of the sphere, oC

To= Outer temperature of the sphere, oC

Determination of heat transfer coefficient= 2 + 0.43 ( ) . for 1<GrPr<105= 2 + 0.50 ( ) . for 3x105<GrPr<8x108

Nu= Nusselt number=h= Heat transfer coefficient, W/m2K

d=Diameter of sphere, m

K=Thermal conductivity of fluid, W/mK, water or oil in case of heating, air in case

of

cooling

Gr= Grashoff’s Number= ∆ρ= Density of air, kg/m3

β= Volumetric thermal expansion coefficient, /K

=1/(Tf+273)

Tf= Mean film temperature, oC

=(To+T∞)/2

T∞= Initial temperature of hot fluid or cold fluid ie, water or air, oC

To= Initial temperature of sphere, oC

∆t= Temperature difference between sphere and fluid, oC

= (T∞ ̴To)

µ= Absolute viscosity of air, N-s/m2

Pr= Prandtle number

Properties of fluid such as ρ, µ, K, Pr are obtained from HMT data book at Tf

Determination of Instantaneous heat flowBi= Biot number=R= Radius of sphere, m

Fo= Fourier Number



=t= Time at the given instant, sec

α= Thermal diffusivity of sphere material, m2/s= − ( − )Qi= Instantaneous heat flow, W

A=Surface area of the sphere, m2

=4r= Radius of the sphere, m

Ti= Initial surface temperature of the sphere, oC, i.e at t=0 sec

Ks= Thermal conductivity of metal ball, W/mK

Determination of theoretical temperatures= eT= Temperature of the sphere in the given time, oC

GRAPHS: Experimental temperature v/s time, Theoretical temperature v/s time

RESULTS: The heat transfer coefficient for transient heat conduction heat transfer is _____

EXPERIMENTAL SETUP OF TRANSIENT HEAT CONDUCTION



EXPERIMENT NO. 5

NATURAL CONVECTION HEAT TRANSFER

AIM: To determine the coefficient of natural convection heat transfer when the cylindrical

surface both in vertical and horizontal

APPARATUS: Natural convection heat transfer experimental setup

THEORY: Write the following theory topics1. Definition of convection heat transfer

2. Types of convection heat transfer, applications

3. Correlations used in natural convection heat transfer.

4. Definition & Significance of Grashoff, Prandtle & Nusselt Numbers.


The apparatus consists of a Chromium plated Copper tube of diameter (d) 38mm

and length (L) 500mm with a Special electrical heater along the axis of the tube for uniform

heating. Four thermocouples are fixed on the tube surface with a phase angle of 90.

An arrangement to change the position of the tube to vertical or horizontal position is

provided.

Front transparent acrylic enclosure to minimize the disturbances of the surrounding and

also for safety of the tube when not in use.

Control panel instrumentation consists of:

Digital Temperature Indicator with channel selector.

Digital Voltmeter & Ammeter for power measurement.

Heater regulator to regulate the input power.

With this, the setup is mounted on an aesthetically designed MS Powder coated frame with

MOVAPAN Board control panel to monitor all the processes considering all safety and

aesthetics factors.

PROCEDURE:

1. Keep the tube in the vertical position.

2. Switch on MCB and then CONSOLE ON switch.

3. Switch on the heater and set the voltage (say 60V) using heater regulator and the

digital voltmeter.





indicator.

6. Note down the ammeter and voltmeter readings.

7. Calculate the convection heat transfer co-efficient using the procedure given below.

8. Repeat the experiment for different heat inputs and also for horizontal position with

different heat inputs.

SPECIFICATIONS:

1. Length of the cylindrical tube= 500mm

2. Diameter of the cylindrical tube=32mm

3. Type of thermocouple= K type (Cr-Al)

4. Maximum voltage =150 volts

PRECAUTIONS:



3. Make sure that heater regulator is at the minimum position before switching on the

console.


TABULAR COLUMN:

Sl.No.

Position Vvolts

IA

T10C

T20C

T30C

T40C

T50C

hexpW/m2K

hthW/m2K

1

Horizontal2

3

1

Vertical2

3

Where

V = Voltage, Volts

I = Input current to heater in amperes

T2, to T5 = Temperatures on surface of the tube, 0C

T1= Ambient temperature, 0C



hexp=Experimental heat transfer coefficient, W/m2K= ( )Q= Heat transfer rate from the cylindrical tube, W= ×As= outer Surface area of the tube, m2

= π Do L

Do= Outer diameter of the tube, m

L= Length of the tube, m

Tm= Mean temperature of the cylindrical tube, 0C=T∞= Ambient temperature, 0C =T1

hth= Theoretical heat transfer coefficient, W/m2K= for horizontal position= for vertical position

Nu= Nusselt number= 0.53 ( ) , when 104 <Gr Pr<109 for horizontal position= 0.59 ( ) , when 104 <Gr Pr<109 for vertical position

Gr= Grashoff Number= ( ) for horizontal position= ( ) for vertical position

ρ=Density of air, kg/m3

β= Volumetric thermal expansion coefficient, /K=Tmf= Mean film temperature, 0C=µ=Absolute viscosity of air, Ns/m2

ρ, µ, K and Pr are obtained from HMT data book at mean film temperature Tmf

RESULTS: Coefficient for natural convection heat transfer is ____________



EXPERIMENTAL SETUP OF NATURAL CONVECTION



EXPERIMENT NO. 6

FORCED CONVECTION HEAT TRANSFERAIM: To determine the coefficient of forced convection heat transfer

APPARATUS: Experimental setup of forced convection heat transfer

THEORY: Write theory on the following topics

1. Definition of convection heat transfer and forced convection heat transfer

2. Practical examples for forced and free convection heat transfer

3. Correlation of forced convection heat transfer

4. Velocity and thermal boundary layer in internal flow through pipe

5. Definition and significance of Reynold’s number


The apparatus consists of

Heat exchanger tube made of copper with steel coating and is thermally insulated outside to

prevent heat losses to the atmosphere.

Band heaters of 500watts capacity.


Digital Voltmeter and Ammeter to measure poser input to the heater.

Thermocouples at suitable position to measure the temperatures of body and the air.


Blower unit to blow air through the heat exchanger with orifice meter and manometer to

measure the air flow rate from the blower. A control valve is provided to regulate the air

flow.

Control panel to house all the instrumentation.

With this the whole arrangement is mounted on an aesthetically designed self-sustained MS

powder coated frame with a separate NOVAPAN Board control panel.

PROCEDURE:

1. Switch on the MCB and then console on switch to activate the control panel.

2. Switch on the blower unit first and adjust the flow of air using wheel valve of blower

to a desired difference in manometer.

3. Switch on the heater and set the voltage (say 80V) using the heater regulator and

digital voltmeter.

4. Wait for reasonable time to allow temperatures to reach steady state.

5. Measure the voltage, current and temperatures from T1 to T6 at known time interval.



6. Calculate the convective heat transfer co-efficient using the procedure given.

7. Repeat the experiment for different values of power input to the heater and blower air

flow rates.

SPECIFICATIONS:1. Pipe length=500mm

2. Diameter of the pipe=38mm (experimental section)


4. Maximum voltage =150 volts

5. Dia. Of pipe & orifice = 38mm & 25mm

6. Co-efficient of discharge of orifice = 0.62

PRECAUTIONS:





console.


TABULAR COLUMN:

Sl.

No.

V

Volts

I

A

T1

oC

T2

oC

T3

oC

T4

oC

T5

oC

hw

m of H2O

hexp

W/m2K

hth

W/m2K

Where

V = Voltage, Volts

I = Input current to heater in amperes

T2, to T4 = Temperatures on surface of the tube, 0C

T1= Ambient temperature, 0C

T5= Air outlet temperature, 0C

hw= Manometer reading, m of water

hexp=Experimental heat transfer coefficient, W/m2K= ( )



Q= Heat transfer rate from the cylindrical tube, W= ×As= Surface area of the pipe, m2

=π DL

D= Diameter of the pipe, m

L= Length of the pipe, m

Tm= Mean temperature of the cylindrical tube, 0C=Tb= Ambient temperature, 0C =T1

hth= Theoretical heat transfer coefficient, W/m2K

Determination of hth=Nu= Nusselt Number= 0.023 × . .Re= Reynolds Number=vm = Mean velocity of air, m/s=ma= Mass of air circulated, kg/s

ma= ρ x Va

ρ= Density of air, kg/m3

Va= Actual volume flow rate of air, m3/s=Cd= Coefficient of discharge of orifice

Ao=Area of orifice, m2=do= Diameter of orifice, m

Ad=Cross sectional area of pipe, m2=



Dp=Diameter of duct, m

Ha= Head of air, m of air= ( − 1)ρ, µ, K and Pr are obtained from HMT data book at bulk mean temperature Tb

RESULTS: Coefficient for forced convection heat transfer is ____________

EXPERIMENTAL SETUP OF FORCED CONVECTION



EXPERIMENT NO. 7

STEFAN BOLTZMAN’S APPARATUSAIM: To determine Stefan Boltzmann Constant for radiation heat transfer

APPARATUS: Stefan Boltzmann Apparatus, stop watch


1. Definition of radiation heat transfer

2. Characteristics of radiation heat transfer

3. Stefan Boltzmann law

4. Intensity of radiation

5. Lambert’s cosine law

6. Solar radiation and green house effect



Copper hemispherical enclosure with insulation.

SS jacket to hold the hot water.

Over head water heater with quick release mechanism and the thermostat to generate and

dump the hot water.


Thermocouples at suitable position to measure the surface temperatures of the absorber

body.





PROCEDURE:

1. Fill water slowly into the overhead water heater.

2. Switch on the supply mains and console.

3. Switch on the heater and regulate the power input using the heater regulator. (say 60 –

85 C)

4. After water attains the maximum temperature, open the valve of the heater and dump

to the enclosure jacket.



5. Wait for about few seconds to allow hemispherical enclosure to attain uniform

temperature – the chamber will soon reach the equilibrium. Note the enclosure

temperature.

6. Insert the Test specimen with the sleeve into its position and record the temperature at

different instants of time using the stop watch.

7. Plot the variation of specimen temperature with time and get the slope of temperature

versus time variation at the time t = 0 sec

8. Calculate the Stefan Boltzman’s constant using the equations provided.

9. Repeat the experiment 3 to 4 times and calculate the average value to obtain the better

results.

SPECIFICATIONS:1. Material of the specimen=copper

2. Mass of the specimen=4.7 g

3. Specific heat of the specimen=410J/kgK

4. Diameter of the specimen=15mm




3. Do not switch on the heater without water in the overhead tank.


5. Do not attempt to alter the equipment as this may cause damage to the whole system

TABULAR COLUMN:

Sl. No. T1oC

T2oC

T3oC

TeK

TsK

σW/m2K4

123

TimeSec

Temperature of thespecimen, oC



Where

Te= Emitter temperature, K+ 273Ts= Initial temperature of Specimen i.e at zero seconds, K

σ= Stefan Boltzmann constant, W/m2K4=Q= Heat transfer rate, W=m= Mass of the test specimen, kg

C=Specific heat of the test specimen, J/kgK

dT/dt= Slope obtained from Temperature of the specimen vs Time graph, K/s

As= Surface area of the specimen, m2=d= Diameter of the specimen, m

RESULTS: Stefan Boltzmann constant is





EXPERIMENT NO. 8

MEASUREMENT OF SURFACE EMISSIVITY

AIM: To determine the emissivity of a given grey body

APPARATUS: Emissivity experimental setup


1. Definition of emissivity, absorptivity, transmittivity, reflectivity

2. Definition of black body, grey body, white body and diathermaneous body

3. Definition of emissive power

4. Plank’s law, Wein’s displacement law, Kirchoff’s law

5. Concept of grey body

6. Parameters affecting on emissivity

DESCRIPTION OF THE APPARATUS:The setup consists of a 200mm dia two copper plates one surface blackened to get the

effect of the black body and other is platened to give the effect of the gray body. Both the

plates with mica heaters are mounted on the ceramic base covered with chalk powder for

maximum heat transfer. Two Thermocouples are mounted on their surfaces to measure the

temperatures of the surface and one more to measure the enclosure/ambient temperature. This

complete arrangement is fixed in an acrylic chamber for visualization. Temperatures are

indicated on the digital temperature indicator with channel selector to select the temperature

point. Heater regulators are provided to control and monitor the heat input to the system with

voltmeter and ammeter for direct measurement of the heat inputs. The heater controller is

made of complete aluminium body having fuse.

With this, the setup is mounted on an aesthetically designed frame with control panel

to monitor all the processes. The control panel consists of mains on indicator, Aluminium

body heater controllers, change over switches, digital temperature indicator with channel

selector, digital voltmeter and ammeter for measurement of power and other necessary

instrumentation. The whole arrangement is on the single bench considering all safety and

aesthetics factors.

PROCEDURE:

1. Give necessary electrical connections and switch on the MCB and switch on the

console to activate the control panel.



2. Switch on the heater of the black body and set the voltage (say 30V) using the heater

regulator and digital voltmeter.

3. Switch On the heater of the Gray body and set the voltage (say 30V) using the heater

regulator and digital voltmeter.

4. Observe temperatures of the black body and test surface in close time intervals and

adjust power input to the test plate heater such that both black body and test surface

temperatures are same.

5. Wait to attain the steady state.

6. Note down the temperatures at different points and also the voltmeter and ammeter

readings.

7. Tabulate the readings and calculate the surface emissivity of the non – black surface.

SPECIFICATIONS:

1. Diameter of black and grey body=20cm


3. Maximum range of voltage =150 volts




console.

4. After finishing the experiment open the acrylic door to remove the heat from the

chamber.


TABULAR COLUMN:

Sl.No. Vb

Volts

Ib

A

Vg

Volts

Ig

A

T1

oC

T2

oC

T3

oC

T4

oC

T5

oC

Qb

W

Qg

W

ɛ

1

2

3

Where

Vb, Ib are the voltage and current supplied to black body

Vg, Ig is the voltage and current supplied to grey body



T1, T2 are temperatures of black body oC

T3, T4 are the temperatures of grey body oC

Qb= Heat input to black body, W

= Vb x Ib

Qg= Heat input to grey body, W

= Vg x Ig

ɛ= Emissivity of grey body=Tb= Average temperature of black body, K

=(T1+T2)/2

Tg= Average temperature of grey body, K

=(T3+T4)/2

Ta=T5= Ambient temperature, K

Alternate method of calculating emissivity= − ~ɛb= Emissivity of black body=1

η= Efficiency of heater=0.86

T=Tb=Tg

σ= Stefan Boltzmann constant=5.67x10-8 W/m2K4

A= Surface area of black or grey body, m2= 4

d= Diameter of the black or grey body, m

RESULTS: Emissivity of given grey body is ___________



EXPERIMENTAL SETUP OF SURFACE EMISSIVITY



EXPERIMENT NO. 9

PARALLEL & COUNTER FLOW HEAT EXCHANGER

AIM: To determine LMTD & Effectiveness of the heat exchanger under parallel and counter

flow arrangement.

APPARATUS: Parallel and counter flow heat exchanger setup


1. Definition of Heat Exchanger and its applications

2. Classification of heat exchangers

3. Explanation of parallel flow and counter flow heat exchanger with temperature

profiles

4. Definition of overall heat transfer coefficient, LMTD, AMTD, effectiveness,

capacity rate,

5. Fouling and fouling factor

6. Advantages of NTU over LMTD


The apparatus consists of concentric tubes. The inner tube is made of copper while

the

outer tube is made of Stainless Steel. Insulation is provided with mica sheet and asbestos

rope for effective heat transfer.

Provision has been made for hot water generation by means of geyser.

Change - Over Mechanism is provided to change the direction of flow of cold water in a

single operation.

ACRYLIC Rotameters of specific range is used for direct measurement of water flow rate.

Thermocouples are placed at appropriate positions which carry the signals to the temperature

indicator. A Digital Temperature indicator with channel selector is provided to measure

the temperature.

The whole arrangement is mounted on an Aesthetically designed self sustained sturdyframe made of MS tubes with NOVAPAN board control panel. The control panel houses

all the indicators, accessories and necessary instrumentations.



PROCEDURE:1. Switch ON mains and the CONSOLE.

2. Start the flow on the hot water side.

3. Start the flow through annulus also.

4. Set the exchanger for parallel or counter flow using the change over mechanism.

5. Switch ON the heater of the geyser.

6. Set the flow rate of the hot water (say 1.5 to 4 Lpm) using the rotameter of the hot

water.

7. Set the flow rate of the cold water (say 3 to 8 lpm) using the rotameter of the cold

water.



indicator.

10. Note down the flow rates of the water and tabulate.

11. Now, change the direction of flow for the same flow rates and repeat the steps 9 to 11.

12. Repeat the experiment for different flow rates of water.

SPECIFICATIONS:1. Diameter of inner pipe=20mm

2. Length of the pipe=1m

PRECAUTIONS:




TABULAR COLUMN:

Sl.No.

Arrangement Vclpm

VhLpm

T1oC

T2oC

T3oC

T4oC

mckg/s

mhkg/s

θmoC

UW/m2K

ɛ

1 Parallel flow231 Counter flow23Where,

Vc= Volume flow rate of cold water, lpm

Vh= Volume flow rate of hot water, lpm



T1, T2 =Inlet and outlet temperatures of hot water

T3, T4= Inlet and outlet temperatures of cold water, in case of parallel flow

arrangement

T3, T4 = Outlet and inlet temperature of cold water in case of counter flow arrangement oC

mc= Vc/60=Mass flow rate of cold water, kg/s

mh= Vh/60=Mass flow rate of hot water, kg/s

θm= Logarithmic Mean Temperature Difference (LMTD), oC=For parallel flow arrangement

θi = Thi-Tci=T3-T1

θo = Tho-Tco=T4-T2

For counter flow arrangement

θi = Thi-Tco=T3-T2

θo = Tho-Tci=T4-T1

U= Overall heat transfer coefficient, W/m2K=Q= Heat transfer rate, kg/s= ( − ) = ( − )Cpc=Cph= Specific heat of cold and hot water=4200 J/kg/K

As= Surface area of inner pipe, m2

=πdl

d and l are diameter and length of the pipe, m

ɛ= Effectiveness of heat exchanger= ( )( ) = ( )( ) for Ch<Cc= ( )( ) = ( )( ) for Cc<Ch

Ch= Capacity rate of hot fluid=mh x Cph

Cc= Capacity rate of cold fluid=mc x Cpc

ALTERNATE METHOD OF CALCULATING EFFECTIVENESS= ( )for parallel flow arrangement



= ( )( ) for counter flow arrangement

C= Capacity ratio=Cmin/Cmax in Ch and Cc, see which one is maximum and

minimum

NTU= Number of Transfer Units=RESULT: LMTD and Effectiveness of

i. Parallel flow heat exchanger are __________

ii. Counter flow heat exchanger are _____________

EXPERIMENTAL SETUP OF HEAT EXCHANGER



EXPERIMENT NO. 10

CONDENSATION APPARATUS

AIM: To determine overall heat transfer coefficient, cold fluid heat transfer Coefficient,

steam

side film coefficient, condensate film thickness

APPARAUS: Condensation experimental setup

THEORY: Write theory on following topics

1. Definition of condensation, applications

2. Types of condensation-explanation

3. Assumptions of Nusselt theory, Reonolds number for condensate flow



Heat exchanger tube made of copper which is placed inside the GLASS CHAMBER of

dimension 100 x 200mm.

Steam Generator with necessary fittings and accessories to generate and supply the steam.

Rotameter to directly measure the flowrate of the water into the condensate tube.

Centrifugal Monoblock Pump with control valves and bypass to regulate the flow of water

through the condenser tube.

Thermocouples at suitable position to measure the temperatures of body and the air.





PROCEDURE:1. Fill water slowly into the water tank and steam generator.

2. Switch on the supply mains and console.

3. Switch on the heater of steam generator to generate the steam.

4. Once the steam is generated follow the steps below.

5. Open the inlet valve and allow the cold fluid to flow through the condenser.

6. Adjust the flow rate of cold fluid to minimum.



7. Open the steam inlet valve and keep steam pressure constant (say 0.2kg/cm²)

throughout

the experiment.

8. After cold fluid temperature becomes steady state, note down the inlet temperature,

out

let temperature and flow rate of cold fluid and also note down the volume of

condensate

collected at the given time interval(say 1min).

9. Keeping steam pressure constant take 4 – 5 readings for different cold fluid flow rate

from minimum to maximum.

10. Repeat the experiment at another constant steam pressure Say, (0.3kg/cm²).

SPECIFICATIONS:1. Outer diameter of inner tube=3.8cm, inner diameter = 3.5 cm2. Length of the tube=18cm3. No. of tubes=1

PRECAUTIONS:



3. Do not give continuous steam without running the cold water.

4. Run the water in the condensate tube for about 5 min after the experiment.


6. Check all the electrical connections before running.

7. Before starting and after finishing the experiment the steam valve should be in shut

position.


TABULAR COLUMN:

Sl.

No.

P

bar

T1

oC

T2

oC

T3

oC

T4

oC

Vw

lpm

Vc

m3

mw

kg/s

mc

kg/s

θm

oC

U

W/m2K

hw

W/m2K

hc

W/m2K

δ

m

1

2

3

Where,

P= Pressure at which steam is supplied, bar or kg/cm2



T1, T2= Inlet and outlet temperatures of cold water, oC

T3= Steam temperature, oC

Vw= Volume flow rate of cold water, lpm

Vc= Volume of condensate collected in time ‘t’ seconds, m3

mw= Mass flow rate of cold water, kg/s

=Vw/60

mc= Mass flow rate of condensate, kg/s= ×θm= Logarithmic Mean Temperature Difference (LMTD), oC=θi= Tv-T1, θo=Tv-T2

Ts= Saturation temperature of condensate or steam, oC at the given pressure (from

steam

table)

U= Overall heat transfer coefficient, W/m2K=Qw= Heat carried away by the cold water, W

=mwCpw (T2-T1)

Cpw= Specific heat of water=4.2kJ/kg K

As= Surface area of the tube, m2

=π DL x N

D and L =Diameter and length of condenser tubes

N= Number of tubes

hw= Heat transfer coefficient at cold water side, W/m2K=Nu= Nusselt Number= 0.023 × . .Re= Reynolds Number=v = Velocity of water, m/s=



A= Cross sectional area of tube, m2

=

ρ, µ, Pr and K for cold water are obtained from HMT data book at bulk mean

temperature Tb=(T1+T2)/2

hc= Film heat transfer coefficient, W/m2K= 0.943 3 2( − ) .K= Thermal conductivity of condensate, W/mK

ρ= Density of condensate, kg/m3

hfg= Enthalpy of evaporation, J/kg (from steam table at Ts)

µ= Dynamic viscosity of condensate, Ns/m2

Tv= Tsat= Vapour or saturation temperature, oC. Obtained from steam table at given

pressure

Ts= Tb=Wall temperature of the pipe, oC

ρ, µ, and K for condensate are obtained from HMT data book at mean film

temperature,

Tmf = (Tv+Ts)/2

δ= Condensate film thickness, m=RESULT:





EXPERIMENT NO. 12

VAPOUR COMPRESSION REFRIGERATION

AIM: To determine the co-efficient of performance (COP) of the vapour compression

Refrigeration system.

APPARATUS: Refrigeration test rig

THEORY: Write theory on following topics

1. Definition of refrigeration, COP, relative COP, TOR, refrigerant, types of refrigerants

2. Working of vapour compression refrigeration

3. Significance of P-H chart, Dry bulb compression, wet bulb compression, super

heating, subcooling, advantages and disadvantages of vapour compression

refrigeration

DESCRIPTION OF THE APPARATUS:The Refrigeration system consists of:

RefrigerantR-134 A is used as a medium to undergo vapour compression cycle

CompressorReciprocating type, capacity1/3 HP, Kirloskar make, used to compress refrigerant vapour at

low pressure from the evaporator to a higher pressure at the condenser inlet

CondenserIs a heat exchanger equipment to condense refrigerant vapor at higher temperature to a liquid

Cooling FanProvided to blow atmospheric air on the condenser to assist cooling of refrigerant in the

condenser

Throttle valveProvided to facilitate expansion of high pressure liquid refrigerant to a low pressure

liquid-vapor mixture at constant enthalpy

Capillary tubePerforms the same function as the throttle valve. It is a fixed length small bore transparent

tubing installed between condenser and evaporator – used to demonstrate the working of the

throttle valve. During the refrigeration experiment, either the throttle valve or the capillary

tube will be used. Switching can be realized by suitable connecting / valve system.

Evaporator



Is a chamber where cooling takes place because of evaporation of evaporation of liquid –

vapor refrigerant at low temperature and pressure. It consists of a metallic bowl having

grooves below the surface through which the refrigerant flows while evaporation

Digital pressure INDICATORSProvided to measure of the refrigerant at compressor inlet and compressor outlet

Temperature Indicators with Channel SelectorProvided to measure temperatures of the refrigerant at Compressor inlet/evaporate outlet,

Compressor outlet / condenser inlet, Condenser outlet /throttling or capillary inlet, Throttling

or capillary exit / evaporate inlet, inside freezer

Digital power meterProvided to measure power input to the compressor

PROCEDURE:1. Switch ON the main and the console

2. Keep either the throttle valve or the capillary tube open Both devices have the same

expansion (or throttling) effect.

3. Switch ON the motor which drives the compression and the fan (which cools the

condenser)

4. The refrigerant passes through the vapour compression cycle as mentioned earlier

resulting in cooling in evaporator chamber or freezer

5. Wait for about 5 minutes and note the temperatures T1 to T5 and pressures P1 and P2

6. Note the power input (P) to the compressor

7. Using the measured temperatures, pressures and power input to the compressor, the

co-efficient of performance and the capacity of the refrigerator can be determined

using the procedure given below

SPECIFICATIONS:1. Refrigerant= R 134a

2. Capacity of the cooling = kg in 24hrs

3. Freezing chamber capacity= mm3

4. Power capacity of the motor= HP


6. Energy meter constant = impulse/KWh

PRECAUTIONS:





3. Do not switch ON the compressor frequently.


system.

TABULAR COLUMN:

Sl.

No.

P1

bar

P2

bar

T1

oC

T2

oC

T3

oC

T4

oC

T5

oC

t

sec

P

W

(COP)th (COP)act (COP)re

Where,

P1=Compressor inlet pressure, bar

P2= Compressor outlet pressure, bar

T1=Temperature at compressor inlet (C)

T2=Temperature at compressor outlet (C)

T3=Temperature at condenser outlet (C)

T4=Temperature at evaporator inlet (C)

T5=Temperature inside freezer (C)

t= Time taken for ‘n’ impulses of energymeter, sec

P=Power input to compressor, kW= × 3600×t= time taken for 5 impulse of energy meter,

n= 5 impulse

k= Energy meter constant, impulse/kWh

(COP)th= Theoretical COP of the refrigeration system=H1= Enthalpy of refrigerant before compression, kJ/kg

H2= Enthalpy of refrigerant after compression, kJ/kg

H4= H3=Enthalpy of refrigerant after expansion, kJ/kg =hf at P2

H1, H2 and H4 are obtained from P-H chart assuming dryness fraction of refrigerant at

inlet of the compressor as 1



(COP)act= Actual COP of the refrigerator

(COP)act= Qa/P

Qa= Heat absorbed, KW= ( )mw= Mass of water stored in the freezer, kg

Cpw= Specific heat of water=4.2kJ/kgK

Twi= Initial temperature of water, oC

te= Time taken to cool water from Twi to Twf, seconds,

Twf = T5

W= power supplied to compressor, KW

(COP)re= Relative COP

= (COP)act/(COP)th

P2 3 2

P

bar

P1 4 1

H kJ/kg

RESULT: The relative COP of the Vapour compression refrigeration system is __________



EXPERIMENT NO. 13

AIR CONDITIONERAIM: To determine COP and TOR of air conditioner and draw psychrometric chart for the various

processes

APPARATUS: Air conditioner test rig

THEORY: Write the theory on following topics

1. Define air conditioning

2. Definition of psychrometry, psychrometric properties

3. Psychrometric process, comfortable air conditioning

4. Classification of air conditioning systems


It consists of a cooling coil which is a part of the vapour compression refrigeration system

working on Freon – 22. In the upstream and downstream of the cooling coil, heaters are

provided to heat air either at the upstream or the downstream of the cooling coil. A steam

generator is provided to increase humidity of air. The system is provided with fans, air duct

and valve system to circulate air over the cooling coil and heater and to operate the system in

both closed and open cycle. The system is instrumented with thermometers, digital humidity

indicators, pressure indictors and wind velocity indicators to determine the state of air –

moisture mixture during the operation of the air conditioning system. Following are the

important components:

Cooling coil of the vapour compression refrigeration system consisting of Compressor,

condenser, throttle / capillary tube, pressure and temperature Indicators with selector switch

and power meter. The system works on Freon-22

Air Heaters - 2 set (3 Nos. of 500 W each), Steam generator which consists of immersion

type heating coil, Suction fan (2 Nos), Valve system to change the system to perform in both

closed and open, Duct system with a window (close / open), Wind Anemometer to measure

air velocity in the duct, Wet Bulb & Dry Bulb Temperatures (2 Nos) placed before and after

evaporator / cooling coil.

Temperature indicator with selector switch to measure air temperature upstream of cooling

coil and downstream of post heater.

Energy meters (2 Nos) for compressor and downstream of compressor

Pressure gauges – at both upstream and downstream of compressor

Pressure switches to limit pressures upstream and downstream of compressor

Thermostat to limit negative temperatures in the cooling coil



PROCEDURE:

The following are the operational procedures for different cycles:

A. OPEN CYLCE – COOLING1. Switch –ON the mains and the console

2. Open the window and set the valve to work the Air Conditioning system in the open

cycle operation

3. Switch –ON the thermostat, keep at maximum

4. Switch –ON all switches

5. Switch –ON the compressor of the refrigeration unit. The cooling coil temperature

begins to fall.

6. Switch –ON the suction fans

7. Switch –ON pre-heater

8. Observe temperatures (T5 and T6) at the inlet and out let of the Air Conditioning

unit till fairly steady state is reached

9. Note T1, T2, T3, T4, T5, T6, P1,P2, V , Pc, t, wet and Dry Bulb Temperatures

B. CLOSED CYCLE – COOLING

Repeat the above procedure (as mentioned in A) with the following changes:

1. Window closed.

2. Valve in Close cycle position to facilitate circulation of air inside the Duct system

3. Additional fan Switched –OFF.

4. Note all parameters as mentioned in A (9)

C. HUMIDIFICATION – OPEN CYCLE OPERATIONRepeat the above procedure (as mentioned in A) with the following:

1. Open the window, position the valve accordingly.

2. Switch- ON both fans

3. Switch – ON both pre –heater and post heater.

4. Switch –ON steam generator


D. SIMULATION OF WINTER AIR CONDITIONING – OPEN CYCLEOPERATION

Repeat the above procedure (as mentioned in A)with the following:1. Open the Window, position the valve accordingly.

2. Switch –ON both fans

3. Switch –ON post heater only (switch – OFF Pre-heater and steam generator)




SPECIFICATIONS:

1. Type of refrigerant=Freon 22

2. Heaters capacity= 500 W

3. Energy meter constant=3200 imp/kWh

4. Thermo couple type= RTD

5. Power capacity of motor = 1/3 HP

PRECAUTIONS:


2. Do not run the equipment if the voltage is below 180V from each line.

3. Minimum time gap of 20min is required to restart the compressor.

4. Do not switch ON the compressor frequently.


system.

TABULAR COLUMN:

Sl.

No.

P1

bar

P2

bar

T1

oC

T2

oC

T3

oC

T4

oC

T5

oC

T6

oC

Tdb

oC

Twb

oC

V

m/s

tc

s

Th

s

Pc

W

Ph

W

COP

1

2

3

Wi

kg/kg

of air

Wf

kg/kg

of air

Φi

%

Φf

%

TOR

Where,

P1=Compressor inlet pressure, bar

P2= Compressor outlet pressure, bar

T1=Temperature at compressor inlet (C)

T2=Temperature at compressor outlet (C)

T3=Temperature at condenser outlet (C)



T4=Temperature at evaporator inlet (C)

T5= Air temperature before it passes over cooling coil (C)

T6= Air temperature after it passes over cooling coil (C)

Tdb= Dry bulb temperature, oC

Twb= Wet bulb temperature, oC

V= Velocity of air, m/s

tc and th are time taken for ‘n’ revolutions of energy meter disc of compressor and

heaters, seconds

Pc= Power supplied to the compressor, W= × 3600×k= Energy meter constant, rev/kWh

Ph= Power supplied to heaters, W= ××COP= Coefficient of Performance of refrigerator=H1= Enthalpy of refrigerant before compression, kJ/kg

H2= Enthalpy of refrigerant after compression, kJ/kg

H4= Enthalpy of refrigerant after expansion, kJ/kg =hf at P2

H1, H2 and H4 are obtained from P v/s H chart assuming dryness fraction of

refrigerant at inlet of the compressor as 1

wi and wf are initial and final specific humidity of air, kg/kg of dry air

Φi and Φf are initial and final relative humidity of air, %

wi, wf, Φi and Φf are obtained from psyhrometric chart

TOR= Ton of Refrigeration or capacity of cooling coil=Qa= Heat absorbed by the refrigerant from air, kJ/kg

Obtained from psychrometric chart (Enthalpy difference between before and after cooling)

ma= Mass flow rate of air cooled, kg/s

= ρAv

ρ= Density of air, kg/m3 A=Cross-sectional area of duct, m2





Chloro difluoro methane (CHClF2) (Freon 22)



VIVA QUESTIONS1. What is the driving force to transfer following

i. Heat transfer ii. Mass transfer iii. Fluid transfer iv. Electrical energy transfer

2. What are the applications of heat transfer?

3. Differentiate between heat transfer and thermodynamics?

4. Define the conduction, convection and radiation heat transfer modes

5. Which mode of heat transfer is most efficient?

6. State the following laws

i. Fourier’s law of heating ii. Newton’s law of cooling iii. Stefan Boltzmann

law

7. What is thermal conductivity?

8. Mention the thermal conductivity of following materials

i. Diamond ii. Gold ii. Copper iii. Aluminium iv. Brick v. Mica vi.

Bakelite

9. Define thermal diffusivity

10. What is the effect of temperature on thermal conductivity of solids, liquids and

gasses?

11. When overall heat transfer coefficient will be used?

12. What is the effect of temperature on thermal conductivity of non-metallic amorphous

solids

13. Due to which reason most metals are good conductors of heat?

14. Write the Laplace, Poisson and Diffusion equations

15. Define heat transfer coefficient

16. Compare Fourier’s law of conduction with Ohm’s law of electricity

17. What is steady state and unsteady state hear transfers? Give examples

18. Define composite wall and overall heat coefficient

19. Define thermal contact resistance

20. Define critical thickness of insulation. What is its significance?

21. Define fin. Mention its function

22. List out the types of fins

23. What are three conditions of fin?

24. Define effectiveness and efficiency of fin

25. What is transient heat conduction? What are its applications?

26. What do you mean by infinite and semi-infinite solids?



27. Define Lumped parameter method.

28. Define Biot and Fourier numbers

29. What is the significance of Biot and Fourier Number?

30. What do you mean by characteristic length? Get the characteristic length of

rectangular slab, cylinder and sphere

31. What are the applications of Heiselrs charts?

32. Give few examples for heat transient heat conduction through semi-infinite solids

33. What is natural convection heat transfer? Give examples

34. List out the parameters affecting on natural convection heat transfer

35. Define local heat transfer coefficient and average heat transfer coefficient

36. Define Grashoff, Nusselt and Prandtle numbers

37. What is the significance of Grashoff, Nusselt and Prandtle numbers?

38. What do you mean by drag coefficient?

39. Define forced convection heat transfer. Give examples

40. What are the parameters affecting on forced convection heat transfer?

41. Define Reynolds number. What is its significance?

42. What is the critical Re when fluid flows over flat plates and through pipes

43. Define Stanton number and Raleigh Numbers

44. Define thermal boundary layer and hydro dynamic boundary layers

45. What do you mean by leading edge and trailing edge?

46. Explain the mechanism of radiation heat transfer

47. What are the characteristics of radiation heat transfer?

48. Define absorptivity, reflectivity and transmittivity

49. Define emissivity

50. Define black body, grey body, white body and diathermaneous body

51. State Stefan Boltzmann law, Kirchhoff’s law, Lambert cosine law, Wein’s

displacement law, Planks law

52. Define emissive power

53. What is the value of Stefan Boltzmann constant

54. Define mano chromatic emissivity, total emissivity, normal total emissivity

55. Define intensity of radiation

56. What do you mean by green house effect?

57. What is radiation shield? What is its effect on heat transfer?

58. Define heat exchanger



59. What are the applications of heat exchanger?

60. Classify heat exchangers

61. What do you mean by compact heat exchanger?

62. What is fouling and fouling factor?

63. Define LMTD and AMTD

64. Draw the temperature v/s length of heat exchanger graph for parallel flow and counter

flow arrangements

65. Define effectiveness of heat exchanger

66. Define capacity rate and capacity ratio

67. Why effectiveness of counter flow heat exchanger is more than that of parallel flow

heat exchanger

68. What is NTU? What are its significances?

69. Define condensation

70. List out the types of condensation

71. Define film condensation and dropwise condensation

72. What are the surface conditions required for dropwise condensation?

73. What is the significance of Nusselt theory?

74. Write Kirkbridge equation for average heat transfer coefficient of condensate flow

75. Define boiling

76. List out the applications of boiling

77. List out the different forms of boiling

78. Define pool boiling

79. Define subcooled boiling

80. Define Nucleate boiling

81. Define film boiling

82. What are the regimes of pool boiling

83. What is excess temperature

84. Define refrigeration

85. Define TOR

86. List out the applications of refrigeration

87. Define COP, relative COP

88. What are the properties of a good refrigerant

89. Classify refrigeration systems

90. List out various types of refrigerants



91. What are the advantages of vapour compression refrigeration

92. Define wet compression, dry compression, super heating and subcooling

93. Draw vapour compression refrigeration on P-H chart

94. What is the chemical name of R-12, R22 and R-134a

95. What is air conditioning

96. What are the applications of air conditioning

97. Define psychrometry

98. Define DBT, WBT, WBD, SH, AH, RH, Specific weight, DPT, Saturation ratio,

adiabatic temperature, enthalpy of saturated air

99. Show following processes on psychrometric chart

Sensible heating, sensible cooling, cooling with dehumidification, humidification,

heating with humidification

100. Classify air conditioning systems

101. What do you mean by comfortable air conditioning

102. Write the Dr. Carrier’s equation

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THERMAL CONDUCTIVITY OF METAL ROD - PESIT Southpesitsouth.pes.edu/pdf/2017/mechanical/HMT LAB MANUAL.pdf · PES IT - BSC [ HEAT TRANSFER LAB] Department Of Mechanical Engineering