AE2207 THERMODYNAMICS LABORATORY 0 0 3 2

OBJECTIVE

To enhance the basic knowledge in applied thermodynamics

LIST OF EXPERIMENTS

1. Performance test on a 4-stroke engine2. Valve timing of a 4 – stroke engine and port timing of a 2 stroke

engine 3. Determination of effectiveness of a parallel flow heat exchanger4. Determination of effectiveness of a counter flow heat exchanger5. Determination of heating value of a fuel6. COP test on a vapour compression refrigeration test rig7. COP test on a vapour compression air-conditioning test rig 8. Determination of specific heat of solid9. Determination of Thermal Conductivity of solid.10.Determination of Thermal Resistance of a Composite wall.

TOTAL : 45 PERIODS

LIST OF EQUIPMENTS

(for a batch of 30 students)

Sl.No Details of EquipmentsQty Req.

Experiment No.

1. 4 stroke twin cylinder diesel engine 1 12. Cut section model of 4 stroke diesel engine and

cut section model of 2 stroke petrol engine1 2

3. Parallel and counter flow heat exchanger test rig 1 3,44. Bomb Calorimeter 1 55. Vapour compression refrigeration test rig 1 66. Vapour compression air-conditioning test rig 1 77. Conductive Heat Transfer set up 1 98. Composite wall 1 10

VALVE TIMING DIAGRAM OF 4S-CI ENGINE

Ex.No:1

Date :

AIM:To draw the valve timing diagram for the given four stroke engine.

EQUIPMENTS REQUIRED:

1. Measuring tape2. Scale3. Thread4. Feeler gauge

FORMULA:

Required angle = Distance x 360 Circumference of the flywheel

Where,Distance = Distance of the valve opening or closing position marked on flywheel

with respect to their dead centre.

PROCEDURE:

1. First the TDC and BDC of the engine are found correctly by rotating the flywheel and the positions are marked on the flywheel.

2. Now the circumference of the flywheel is found by using the measuring tape.3. The flywheel is rotated and the point at which the inlet valve starts opening is

found out and its position is marked on the flywheel.4. Similarly the position at which it closes is also found out.5. The distances are measured by using thread with respect to their dead centre and

converted into angles.6. The same procedure is repeated for the exhaust valves also.

RESULT:

Thus the valve timing for the given four stroke engine is found out and is drawn.

Inlet valve opens = Inlet valve closes =

Exhaust valve opens = Exhaust valve closes =

TABULATION:

EventDistance from their

respective dead centres in “cm”

Valve opening period in degrees

Inlet valve opens

Inlet valve closes

Exhaust valve opens

Exhaust valve closes

PORT TIMING DIAGRAM OF 2S-SI ENGINE

Ex.No : 02

Date :

AIM:

To draw the port timing diagram for the given two stroke engine.

TOOLS REQUIRED:

1. Measuring tape2. Scale3. Thread

FIXING THE DEAD CENTRES:

For fixing up the dead centre a chalk mark is made on the piston. The fly wheel is rotated. When the chalk mark coincides with the end of the cylinder a mark is made on the flywheel and it represents TDC.

Now the flywheel is again rotated and the position at which the piston reaches the lower most position is noted on flywheel and it represents the BDC.

IDENTIFICATION OF POSTS:

The port which has more area and is nearer to the TDC is the exhaust port and the other is the inlet port.

DIRECTION OF ROTATION:

As the port opening and closing are symmetrical about the dead centre any arbitrary direction of rotation may be selected.

FORMULA:

Required angle = Distance x 360 Circumference of the flywheel

Where,Distance = Distance of the valve opening or closing position marked on flywheel

with respect to their dead centre.

PROCEDURE:

1. The flywheel is turned in any arbitrary direction.2. During the downward traverse position when it just uncovers a port it is marked as

the opening of the port on the flywheel.3. The rotation is further continued until the piston covers the port during its upward

travel.4. A mark is made on the flywheel against the fixed mark. This gives the closing of

the port.5. The same procedure is repeated for other ports also.

RESULT:

Thus the port time for the given two stroke engine is found out and the port timing diagram is drawn.

Transfer port opens = Transfer port closes = Exhaust port opens =Exhaust port closes =

TABULATION:

EventDistance from their

respective dead centres in “cm”

Valve opening period in degrees

Exhaust port opens

Exhaust port closes

Transfer port opens

Transfer port closes

PERFORMANCES TEST ON FOUR STROKE SINGLE CYLINDER SLOW SPEED DIESEL ENGINE

Exp.No: 03

Date :

AIM: To find the performances characteristics of four stroke single cylinder vertical

diesel engine.

APPARATUS REQUIRED:

Engine test rig. Tachometer, Stop watch, Measuring tape.

ENGINE DETAILS:

Engine type :

Power :

Bore :

Stroke :

Calorific value :

Specific gravity :

FORMULAE:

1. Brake power:

B.P = 2 π N R (W-S) 9.81 kW 60x1000

Where,

N = Engine speed in rpmR = Brake drum radius in cmW = Dead weight added in Kg S = Spring Balance reading in Kg

2. Total Fuel consumption:

T.F.C = cc x Specific gravity x 3600 kg / hr tf 1000

Where,

tf = Time taken to consume 10cc of fuel in secondscc = Amount of fuel consumption measured in cc

3. Specific fuel consumption:

S.F.C. = T.F.C kg / kW – hr B.P

4. Friction power:

Values taken from graph(BP Vs TFC)

5. Indicated power:

I.P = B.P + F.P kW

6. Mechanical efficiency:

Mech = B.P x 100 % I.P

7. Indicated thermal efficiency:

Ith = I.P x 3600 x 100 % T.F.C x C.V

8. Brake thermal efficiency:

Bth = B.P x 3600 x 100 % T.F.C x C.V

Where,C.V = Calorific value of fuel in kJ / kg(43000 kJ/kg)

9. Indicated mean effective pressure:

I.M.E.P = I.P x 60000 N/m2

L.A.N.k

10.Torque = B.P x 60 2 n

11.Brake mean effective pressure:

B.M.E.P = B.P x 60000 N/m2

L.A.N.k

Where,L = Stroke length, mA = Area = / 4 D2 D = Bore dia in mN = Speed / 2(for a 4Stroke engine)K = Number of cylinders

DESCRIPTION:

The engine is four stroke, single cylinder, water cooled vertical diesel engine. The engine is connected to rope brake dynamometer. The burette is connected to the engine through three way cock to measure the fuel consumption.

PROCUDURE:

1. The fuel is first filled in the fuel tank.2. Then the cooling arrangements are made.3. Before starting the engine the brake drum circumference is noted.4. Before starting check and assure that there is no load on the weight

hanger.5. Now the engine is started and the time taken for 10cc of fuel

consumption is noted with the help of a stop watch. This reading corresponds to no load condition.

6. Now place weight in the weight hanger and take the above mentioned readings. The spring balance reading is also noted down.

7. The above procedure is repeated for various loads and the readings are tabulated.

8. The calculations are done and various graphs are plotted.

GRAPH:

1. B.P vs. T.F.C.2. B.P vs. S.F.C.3. B.P vs. mech4. B.P vs. ith5. B.P vs. bth6. B.P vs. Torque7. B.P vs. BMEP

RESULT:

Thus the load test on single cylinder four stroke vertical diesel engine is performed and its load characteristics are obtained.

TABULAR COLUMN:

Spring Balance Error = Circumference of Brake drum =

Ser

ial n

umbe

r

Spe

ed r

pm

Dea

d

COP TEST OF AIR CONDITIONING UNIT

AIM: To conduct performance test on air conditioning unit to determine the co-efficient of performance.

SPECIFICATIONS:

TYPE : ALTECH Vapour compression refrigeration – air conditioning.

CAPACITY: Freon 12REFRIGERANT : Hermatically sealed compressorCONDENSOR : Air cooled – finned tube.EVAPORATOR : Finned tube with air flow duct surrounding POWER MEASUREMENT : By energy meter to get power input to the entire set , motor ,condensed fan, air blower.THROTTLING EXPANSION SYSTEM : Capillary tube or thermostatic expansion valve.AIR FLOW : By a blower.AIR FLOW MEASUREMENT : By pitot tube.AIR FLOW DUCT : 0.37*0.17 sq.m

DESCRIPTION : The test rig consists of basic vapour compression refrigeration system along with air flow system. The refrigeration side consists of hermatically sealed compressor, condenser, and an evaporator. This refrigeration unit can be operated either with the thermostatic expansion valve or with the capillary tube as expansion device by using the control valves. The evaporator unit consists of a number of coils and forms as liquid refrigerant air heat exchanger. This unit absorbs heat from the air to be chilled. A blowe is used to circulate the air through the evaporator. A thermostat is provided to cut off the compressor when the air temperature reaches the required set value. A pitot tube is provided to measure the mass flow rate of air which is cooled.

EXPERIMENTAL PROCEDURE :

1. Note the ambient dry bulb and wet bulb temperatures of atmospheric air.2. By controls put in to operation the thermostatic expansion valve in the refrigerant

line.3. Turn on the air conditioner unit and set the thermostat at the required chill

temperature.

4. at steady state condition note the wet bulb and dry bulb temperature of the chilled air in the duct.

5. Measure the air pressure difference across the pitot tube using the water manometer provided in the air duct.

6. Note the time taken for 10 revolution of energy meter disc to calculate the input energy to the air conditioner as a whole. This includes power input to compressor, condenser fan, air flower.

7. Repeat the experiment putting capillary tube into the operation cutting off the thermostatic expansion valve.

AIR SIDE OBSERVATION :

S.NO Measuring points

Dry bulb temp Wet bulb temp Specific enthalpy from

chart.

1 Ambient air T1d T1w H1

2 Chilled air after evaporator coils

T2d` T2w H2

Pitot tube water manometer level difference in the air duct = dH cm of water.

MODEL CALCULATION :

(1) AIR FLOW RATE :

Pitot tube water manometer level difference = dH cms of waterManometer pressure difference Dp = dH * density of water / density of airAir velocity V = ( 2* g* dP)^0.5 m/sec = 13.0(dH)^0.5 m/secMass flow rate of air M = duct c.s area * velocity * density of air = 1.16* A* V kg/sec = 1.16 * A * 13.0(dH)^0.5 kg/sec

(2) REFRIGERATION EFFECT :

Condition 1 refers to ambient and 2 refers to the chilled air Ambient dry bulb temp = t1d

Ambient wet bulb temp = t1w

Chilled dry bulb temp = T2D

Chilled wet bulb temp = T2W

From the psychometric chart,Total enthalpy of air at condition 1 = h1 KJ/Kg

Total enthalpy of air at condition 2 = h2 KJ/KgHeat removed from air per kg = (h1-h2) KJ/KgTotal heat removed by the air conditioner = M *(h1-h2) KJ/Kgi.e, refrigeration effect

(3) INPUT ENERGY TO THE AIR CONDITIONER :

Energy meter constant N = 1200 rev / kw hrTime taken for 10 rev of energy meter disc = t secInput energy E = (3600*100) / ( N * t) k w = ( 30/t) k w (4) COP OF AIR CONDITIONER : COP of air conditioner = refrigeration effect / input energy

COP TEST ON REFRIGERATION UNIT

AIM:To conduct performance test on an refrigeration unit to determine the co-efficient

of performance

SPECIFICATIONS:

Type ALTECHVapour compression refrigeration-air conditioning

Capacity : tonneRefrigerant : FREON 12Refrigerant compressor : Hermatically sealed compressor Condenser : Air-cooled – fine tubeEvapourator : Fine tube with air flow duct surrounding Power measurement : By energy meter to get power input to the entire set, motror , condenser fan, air blower.Throttling expansion system : capillary tube or thermostatic expansion valve

Any one may be used by controlsAir flow : By a blowerAir flow measurement : By pitot tubeAir flow duct : .37*.17 m^2

DESCRIPTION:The test rig is a vapour compression system using the refrigeration

Freon 12. The system consists of a compressor, a condenser, an expansion device and a evaporator. For throttling expansion, two devices are provided.

1) capillary tube2) thermosetting expansion valveAny one of the two devices may be used by closing the other one with the controls.

A chilled water is calorimeter used as a evaporator. It consists of a refrigerated SS vessel of required capacity placed inside a well insulated wooden box and provided with

1) evaporator coil2) manual stirrer3) electric heater 230 V, AC4) the sensing bulb of a low temperature thermostat

5) a high temperature thermostat6) a thermometer to measure the chilled water temperature

EXPERIMENTAL PROCEDURE:

1) Select the thermostatic expansion valve by opening the shut off valve on this line and closing the one on the capillary line. The solenoid manual switch is switched ON.

2) Start the compressor and run for some time so that the chilled water temperature in the evaporator calorimeter is lowered to about 15’C.

3) Switch on the heater and slowly increase the power so that an equilibrium is reached between refrigeration capacity at about 15”C and heater input while the compressor runs without ON-OFF regulation. If the ON-OFF switch cuts-off , increase the heater input and again balance at 15’C.

a) Connect energy meter to motor by keeping the knob on the selector switch against position M. Note time taken for 5 rev of the energy meter disc.

b) Rotate the selector switch knob and keep against H so that energy meter is connected to heater.

c) Note the pressure and temperature readings at locations 1,2,3 & 4 mentioned in table1.

d) Switch off the heater and the mains.

REPEAT THE REFRIGERATION LOAD TEST WITH CAPILLARY TUBE AS EXPANSION DEVICE:

1) select the capillary tube line by opening the shut off valve on this line and closing the one on the thermostatic expansion valve line. The solenoid manual switch is switched OFF.

2) Repeat the procedure described earlier.

DATA SHEET:

Sl.No Expansion Device Using Capillary Tube

Using Thermal Expansion valve

1 Ambient Temperature ‘C ‘C

2 Evaporator chilled water temperature ‘C ‘C

3 Time taken for 5 rev of energy meter disc

Comp.Sm secHeater.So sec

Comp.Sm secHeater.So sec

Measuring Points Kg/Cm^2

Kg/Cm^2

‘C

KJ/Kg Kg/Cm^2

Kg/Cm^2

‘C

KJ/Kg

1. Evaporator Outlet Compression Suction P1 T1 h12. Compressor Outlet Condenser Inlet P2 T2 h23. Expansion Device Condenser Outlet P3 T3 h34. Expansion Device Evaporator Inlet P4 T4 h4

CALCULATIONS:

1) Heat equivalent of work input to compressor per minute, Qc KJ/min.

Time taken for 5 rev of energy meter disc, Sm = sec.Meter constant =1200 rev/KWH.Motor input power,

Qm= 5*3600*60 =900 KJ/min1200*Sm Sm

Mechanical efficiency of compressor=80%Qc=.80*Qm KJ/min

2) Refrigerating effect equal heater input power = Qo Kj/min

Time taken for 5 rev of energy meter disc, So = sec.

Qo=900 KJ/min So

Refrigeration Capacity = Refrigeration Effect210

= Qo Tonne 210

3) Actual Co-Efficient of performance of the refrigerating system.

C.O.P for cooling = refrigeration effect =Qo Heat equivalent of compressor work input Qc

4) Refrigeration circulation rate.

M= Qo*60 Kg/min Q

Where Q= (h1-h2)h 1 = enthalpy corresponding to P1 & T1h 3 = h 4 = enthalpy corresponding to P3 & T3

Refrigeration circulation rate, m

m= 211 (Kg/ton of refrigeration) q

(1 TR = 211 KJ/min)

Theoritical COP = h 1- h 4 h 2- h 1

Actual COP = actual COP Theoretical COP

TEMPERATURE DEPENDENCE OF VISCOSITY OF LUBRICANTION OIL BY REDWOOD VISCOMETER

EX.NO:.8DATE:

AIM: To determine the viscosity of a fluid or liquid by virtue of which it offers resistance to its own flow. It is measured in poise. The kinematic viscosity of a liquid is the ratio of absolute viscosity to its density for the given temperature. The unit for kinematic viscosity is centistokes. Viscosity is the most important single property of any lubricating oil, because it’s the main determinant of the operating characteristics of the lubricant. If the viscosity of the oil is too low, a liquid oil film cannot be maintained between to moving or sliding surfaces, consequently excessive wear will take place. On the other hand if the viscosity is too high, excessive friction will result due to fluid friction. Measurement of viscosity of lubricating oil is made with the help of an apparatus called the viscometer. In a viscometer, a fixed volume of liquid is allowed to flow from given height through a standard capillary tube under its own weight and the time of flow in secondss is noted. The time is proportional to true viscosity. Redwood viscometer is commonly used in commonwealth countries.

Redwood viscometer is of two types: Redwood viscometer No:1 is commonly used for determining viscosities of thin lubricating oils and it has a jet of bore diameter 1.61 and length 10mm. Redwood viscometer No.2 is used for measuring viscosities of highly viscous oils. It has a jet of diameter 3.8mm and length 15mm.

FORMULA:1. Density (D) = D15[1-A(T-15)]kg/m^3.

Where, D15=Density of given oil=866kg/m^3 A=.00036 a constant T= Temperature of oil.

2. Kinematic viscosity (v)=At-B/t*10^-6 m2/s Where,

A=.247, B=65, for T=85 to 200 seconds T= Time taken to collect 50ml in seconds A=.264, B=190, for t=40 seconds 3. Dynamic viscosity (m)= D*v NS/m2

PROCEDURE:1. The leveled oil cup is cleaned and ball valve rod is placed on the gate jet to close it.2. Oil under test free from any suspension and dust is filled in the cup upto the pointer

level.3. An empty conical flask is kept just below the jet.4. Water is filled the bath and side-tube is heated slowly with constant stirring of the

bath.5. When the oil is at the desired temperature, the ball valve is lifted and suspended

from thermometer bracket.6. The time taken to collect 50ml of oil in the flask is noted and the valve is

immediately closed to prevent any overflow of oil.7. The result is expressed in redwood No.1 seconds at particular temperature.8. Similarly the above procedure is repeated for the oil at various temperatures and the

viscosity is found out.9. Now a graph is drawn between the temperature and viscosity of oil.

GRAPH:1, Temperature Vs Kinematic Viscosity2, Temperature Vs Dynamic Viscosity

RESULT:Thus the viscosity of the lubricating oil is found out using Redwood Viscometer

and the graphs are drawn.

COMPOSITE WALLS APPARATUSEXP NO 7

The apparatus consists of a plates of different materials sandwiched between two aluminium plates. Three types of slabs are provided on both sides of heater which forms a composite structure. A small hand press frame is provided to ensure the perfect contact between the slabs. A dimmerstat is provided for varying the input to the heater and measurement of input is carried out by a Voltmeter and Ammeter.Thermocouples are embedded between interfaces of input slabs, to read the temperatures at the surface.

The experiment can be conducted at various values of input and calculation can be made accordingly.

SPECIFICATIONS

1. Slabs sizea. M. S. - 25 cm x 25 mm thickb. Bakelite - 25 cm x 10 mm thickc. Brass - 25 cm x 10 mm thick

2. Nichrome heater wound on mica former and insulator with control unit capacity 200 watt maximum

3. Heater control unit - 230 V 0-2 A single phase Dimmerstat (1 No.)4. Voltmeter - 0-250 volts5. Ammeter - 0-1 Amps6. Multi channel digital temperature indicator

EXPERIMENTS TO BE CARRIED OUT

a. To determine total thermal resistance of composite wallb. To plot temperature gradient along composite wall structure

EXPERIMENTAL PROCEDURE

1. Arrange the plates properly (symmetrical) on both side of heater plate. See that plates are symmetrically arranged on both sides of heater plate (arranged normally)

2. Operate the hand press properly to ensure perfect contact between the plates3. Close the box by cover sheet to achieve steady environmental conditions4. Start the supply of heater. By varying the dimmerstat, adjust the input (range 30-70

watts) and start water supply5. Take readings of all the thermocouples at an interval of 10 minutes until steady

state is reached6. Note down the steady state readings in the observation table

WALL THICKNESS CONDUCTIVITY

a. M. S. = 2.5 cm 0.46 W/mKb. Bakelite = 1.0 cm 0.12 W/mKc. Brass = 1.0 cm 110 W/mK

OBSERVATIONS

Sl. No. Heat supplied (W) Temperatures ‘CVoltmeter Ammeter T1 T2 T3 T4 T5 T6 T7 T8

CALCULATIONS

1. Mean Readingsa. TA = (T1+T2)/2 ‘Cb. TB = (T3+T4)/2 ‘Cc. TC = (T5+T6)/2 ‘Cd. TD = (T7+T8)/2 ‘C

2. Rate of heat supplied

Q = V x I Watts

For calculating the thermal conductivity of composite walls, it is assumed that due to large diameter of the plates, heat flowing through central portion is unidirectional i.e. axial flow. Thus for calculations, central half dia. Area where unidirectional flow is assumed is considered. Accordingly thermocouples are fixed at close to centre of the plates.

Now,

Heat flux, q = [Q/A] Watts/m2

Where,

A = [3.14/4]x d2

Where, d = half dia. Of platesA = 0.0122718 m2

1. Total thermal resistance of composite slab

R TOTAL = [TA-TD] / q m2 ‘K/W

2. Thermal conductivity of composite slab

KCOMPSITE = {q.b/[TA-TD]} W/m/K

b = total thickness of composite slab= 0.045 m

3. To plaot thickness of slab material against temperature gradient.

NOTE : The heat flowing through different slabs does not essentially flow in axial direction but a part of it also goes radial outwards. Hence, real heat flow in axial direction for whole area of slabs is not known and hence by just knowing the temperature difference, thermal conductivity of the slabs cannot be determined.

PRECAUTIONS

1. Keep the dimmerstat zero before start2. Increase voltage slowly3. Keep all the assembly undisturbed4. Remove air gap between plates slowly by moving hand press gently5. When removing the plates do not disturb the thermocouples6. Do not increase voltage above 200 V7. Operate selector switch of temperature indicator slowly

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