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Te lab ii manual, Study Guides, Projects, Research of Materials science

Thermal Engineering Lab Manual

Typology: Study Guides, Projects, Research

2014/2015

Uploaded on 11/18/2015

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1
INDEX
S NO
DATE
EXPERIMENT
PAGE
NO
MARKS
SIGNATURE
1
THERMAL CONDUCTIVITY
OF PIPE INSULATION USING
LAGGED PIPE
APPARATUS
3
2
HEAT TRANSFER THROUGH
A VERTICAL PIPE BY
NATURAL CONVECTION
8
3
HEAT TRANSFER THROUGH
A HORIZONTAL PIPE BY
FORCED CONVECTION
15
4
HEAT TRANSFER FROM A
PIN FIN APPARATUS (Natural
& Forced Convection Modes)
22
5
STEFAN BOLTZMANN
CONSTANT
31
6
EMISSITIVITY
MEASUREMENT APPARATUS
37
7
PARALLEL FLOW COUNTER
FLOW HEAT HEXGHANGER
41
8
PERFORMANCE TEST ON A
REFRIGERATION SYSTEM
49
9
PERFIRMANCE TEST ON A
AIR-CONDITIONING SYSTEM
55
10
PERFORMANCE TEST ON
SINGLE/TWO STAGE
RECIPROCATING AIR
COMPRESSOR.
61
11
PERFIRMANCE TEST ON A
AIR-CONDITIONING SYSTEM
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INDEX

S NO DATE EXPERIMENT PAGE NO MARKS SIGNATURE

1

THERMAL CONDUCTIVITY OF PIPE INSULATION USING LAGGED PIPE APPARATUS

3

2

HEAT TRANSFER THROUGH A VERTICAL PIPE BY NATURAL CONVECTION

8

3

HEAT TRANSFER THROUGH A HORIZONTAL PIPE BY FORCED CONVECTION

15

4

HEAT TRANSFER FROM A PIN FIN APPARATUS (Natural & Forced Convection Modes)

22

5 STEFAN BOLTZMANN CONSTANT 31

6 EMISSITIVITY MEASUREMENT APPARATUS 37

7 PARALLEL FLOW COUNTER FLOW HEAT HEXGHANGER 41

8 PERFORMANCE TEST ON A REFRIGERATION SYSTEM 49

9 PERFIRMANCE TEST ON A AIR-CONDITIONING SYSTEM 55

10

PERFORMANCE TEST ON SINGLE/TWO STAGE RECIPROCATING AIR COMPRESSOR.

61

11 PERFIRMANCE TEST ON A AIR-CONDITIONING SYSTEM

Specifications:

  1. Diameter of heater rod = 20mm
  2. Diameter of heater rod with asbestos = 40mm
  3. Diameter of heater rod with asbestos and saw dust = 80mm
  4. Effective length of above setup of cylinder = 420mm

Theory:

It has a thermal insulation structure placed around a central core of longitudinal axis and it is characterized in that the thermal insulation structure comprises at least one layer consisting of separate solid strips, each strip being wound with a very long pitch and a maximum wind angle to the horizontal axis of less than 30°

Pipe Insulation is thermal insulation used to prevent heat loss and gain from pipes, to save energy and improve effectiveness of thermal systems.

The benefits include, in addition to reducing costs and environmental impacts of energy consumption:

Reducing or eliminating condensation on cold pipes.

 Protection from dangerous pipe temperatures.  In domestic hot-water systems, the water temperature at the point of use can be closer to the temperature at the water heater, and wait time for hot water can be reduced  Control of noise.  Reduction of unwanted heat gain to air-conditioned spaces.

PROCEDURE:

  1. Switch ON the unit and check if air channels of temp indicator showing proper temperature.
  2. Switch ON heater using regulator and keep power input at port value.
  3. Allow the unit to stabilize for about 20 to 30 minutes.
  4. Now note down ammeter, voltmeter reading giving the head input temp 1,2,3 the temp of heater 4,5,6 and asbestos layer 7,8,9 and saw dust clogging.
  5. Average temperature of each cylinder is taken from calculation
  6. Temperature is measured by thermocouple with multiplied digital temperature indicator.
  7. Experiment may be repeated for different heat input.

Result: Thermal conductivity of lagged pipe is i. K 1 (Asbestos) = _________________w/mº C

ii. K 2 (Saw Dust) = _________________ w/mº

Ex. No: 2 (^) HEAT TRANSFER THROUGH A VERTICAL PIPE BY

Date :^ NATURAL

AIM:

To determine the surface heat transfer coefficient for the vertical tube losing heat by natural convection.

APPARATUS REQUIRED:

  1. Natural convection apparatus
  2. Stop watch

Formula Used:

= π DL Where D = 0.038 & L= 0.

Tabulation:

Thermocouple reading (oC) S.No Time(Min) T1^ T2^ T3^ T4^ T5^ T6^ T7^ T

PROCEDURE:

  1. Switch ON the power supply and adjust the dimmer stat to obtain the require heat input.
  2. Wait till the fairly steady state is reached, which is confirmed from temperature readings (T 1 +T 7 ).
  3. Note down the surface temperature at the various points.
  4. Note the ambient temperature (T 8 )
  5. Repeat the experiment at different heat inputs.

Specifications:

  1. Outside diameter of the pipe, Do = 33mm
  2. Inside diameter of the pipe, Di = 28mm
  3. Length of the tube = L = 400mm
  4. Blower capacity = 0.21 KW
  5. Orifice diameter =14mm connected to manometer.
  6. Dimmer stat range = 0-2 amps,0-230 V
  7. Temperature indicator range = 0-300^0 C
  8. Voltmeter and ammeter range = 0-200 V and 0-2 amps
  9. Heater = 400 Watts

Theory:

Forced convection is a mechanism, or type of heat transport in which fluid motion is generated by an external source (like a pump, fan, suction device, etc.). It should be considered as one of the main methods of useful heat transfer as significant amounts of heat energy can be transported very efficiently and this mechanism is found very commonly in everyday life, including central heating, air conditioning, steam turbines and in many other machines. Forced convection is often encountered by engineers designing or analyzing heat exchangers, pipe flow, and flow over a plate at a different temperature than the stream (the case of a shuttle wing during re-entry, for example). However, in any forced convection situation, some amount of natural convection is always present whenever there are g-forces present (i.e., unless the system is in free fall). When the natural convection is not negligible, such flows are typically referred to as mixed convection.

Viva Voice Questions:

  1. Significance of Reynolds’s number?
  2. Difference between heat ant temperatures?
  3. How is natural convection different from forced convection?
  4. What is the range of values for the emissivity of a surface?
  5. What is the Fourier number?

AIM: To determine the average surface heat transfer coefficient for a pipe losing heat by forced convection by air flowing through it.Reyonld’s number and nusselt number for each experimental condition to be calculated.

APPARATUS REQUIRED:

1. Forced convection apparatus 2. Stop watch

FORMULAE:

1.

2.

3.

4.

5.

6.

7.

8.

Ex. No: 3 HEAT TRANSFER THROUGH A HORIZONTAL PIPE BY FORCED CONVECTION Date :

RESULT:

i. Surface heat transfer coefficient, ha = _______________ ii. Reynolds number, Re = _______________ iii. Nusslet number Nuthe = _______________ Nuact = _______________

Specifications: Diameter of pin fin, D = 0.012m

Theory: In the study of heat transfer, a fin is a surface that extends from an object to increase the rate of heat transfer to or from the environment by increasing convection. The amount of conduction, convection, or radiation of an object determines the amount of heat it transfers. Increasing the temperature difference between the object and the environment, increasing the convection heat transfer coefficient, or increasing the surface area of the object increases the heat transfer. Sometimes it is not economical or it is not feasible to change the first two options. Adding a fin to an object, however, increases the surface area and can sometimes be an economical solution to heat transfer problems.

Viva Voice Questions:

  1. Explain Fin?
  2. What are the types of fins?
  3. Application of Fins?
  4. Define Fin Efficiency?
  5. Define Fin Effectiveness

Forced Convection: 1.

2. m^3 /s

Where, H = difference in levels in manometer

ρw = density of water = 1000 Kg/m^3 ; ρa = density of air at Tmf T 0

3.

4.

5.

6.

TABULATION:

Forced convection:

S.No V(volts) (^) (amps)I^ Fin temperature^

(^0) C Ambient temperature T1 T2 T3 T4 T5^ T

Natural Convection:

S.No V(volts) (^) (amps)I^ Fin temperature^

(^0) C Ambient temperature T1 T2 T3 T4 T5^ T

PROCEDURE :

Procedure:

1. Natural convection: 1. Start heating the fin by switching ON the heater element and adjust the voltage on dimmer stat to say 80 V (increase slowly from zero onwards). 2. Note down the thermocouple readings 1 to 5. 3. When the steady state is reached, record the final reading also records the ambient reading 6. 4. Calculate the heat transfer coefficient and effectiveness of the pin fin using heat transfer relations. 2. Forced convection: 1. Start heating the fin by switching ON heater element and adjust the voltage on dimmer stat equal to 100 V (increase slowly from zero onwards). 2. Start the blower and adjust the difference of level in the manometer with help of gate valve. 3. Note down the thermocouple reading 1 to 5 at the time interval of 5 mins. 4. When the steady state is reached record the final reading 1 to 5 and also record the ambient temperature reading 6. 5. Calculate the heat transfer coefficient and effectiveness of the fin pin using heat transfer relations

Specifications:

  1. Hemisphere diameter = 200mm
  2. Base plate, Bakelite diameter =240mm
  3. Sleeve size diameter = 44mm
  4. Test disc diameter = 20mm
  5. Mass of the disc = 0.005 kg
  6. Specific heat of test disc = 0.418 kj/kgoc
  7. No of thermocouples = 5
  8. Water heater capacity = 1.5 kw

Theory:

The Stefan–Boltzmann constant (also Stefan's constant), a physical constant denoted by the Greek letter σ , is the constant of proportionality in the Stefan–Boltzmann law: the total energy radiated per unit surface area of a black body in unit time is proportional to the fourth power of the thermodynamic temperature.

The value of the Stefan–Boltzmann constant is given in SI by

Viva Voice Questions: a. Stefan Boltzmann constant b. State Stefan Boltzmann law? c. What is a black body?

Aim:

To find out the relative viscosity, kinematic viscosity and absolute viscosity of oil sample

by using redwood viscometer and study the variation of viscosity with change in temperature.

Apparatus Required:

1. Stefan Boltzmann apparatus 2. Stop watch

FORMULAE:

Where σ = Stefan Boltzmann constant, ms = Mass of disc in kg dT/dt = Rate of rise in temperature.

Model graph:

Ex. No: 5 STEFAN BOLTZMANN CONSTANT Date :