Military Institute of Science and Technology (MIST)

Mirpur Cantonment, Dhaka-1216

Department of Naval Architecture and Marine Engineering

NAME 310

Marine Engineering Lab - I

Level 3, Term II

Contact hours: 1.5 Credit hours: 3.0

Prepared By:

TA Ridoy Karmoker Rudro

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 Experiment No. 01
Name of the Experiment: Introduction of Marine Engine Different parts.

Theory: Marine engines play a vital role in powering ships, boats, and other watercraft,
enabling them to navigate the vast oceans and waterways. These engines are specialized
internal combustion engines designed to withstand the harsh marine environment and provide
reliable and efficient performance. Understanding the different parts of a marine engine is
essential for maintenance, troubleshooting, and ensuring the smooth operation of marine
vessels.
Cylinder Head Assembly
The cylinder head assembly is a vital part of any engine, especially with the AC as the overhead
camshaft design means that all the valves, rockers and the driven timing gear are carried in
the head.

Cylinder Block
The cylinder block is one of your engine's central components. It plays a key role in
the lubrication; temperature control and stability of the engine and it has to be of the
highest quality so there is no room for short cuts. cylinder block made with gray cast iron and
aluminum. Gray cast iron delivers more strength while aluminum is very lightweight.

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Part of Piston
A piston is a moving part enclosed in a cylinder which is made gas-tight by piston rings. The
disk moves inside the cylinder as a liquid or gas inside the cylinder expands and contracts.
made with steel, aluminum alloys, cast iron are mostly used. Aluminum is used when lighter
weight piston is needed and steel alloy can withstand high temperature.

Part of Rocker arm

The arrangement fitted over the cylinder head and ensure opening and closing of engine valve.

Push Rod
Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion
from the camshaft to the valves.

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Engine Valve and Valve Spring

• Intake Valve & Exhaust Valve: There are two types of engine valves; intake and
exhaust valves. The intake valves of course let air in, and the exhaust
valves let exhaust air out.
• Valve springs: A helical spring used to hold opened and closed a valve in the cylinder
head of an engine.
Part of Connecting Rod
The connecting rod converts the reciprocating motion of the piston into the rotation of the
crankshaft. A connecting rod with a tension load is made of forged steel, cast steel, or
fabricated steel. Rods with a compression loading are cast nodular steel or aluminum alloy.

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Big End Bearing
Big End Bearing Located at the 'Big End' of the Connecting Rod, where it connects to the
Crankshaft.

Part of Crank Shaft

A crankshaft is a rotating shaft which converts reciprocating motion of the pistons into
rotational motion. Crankshafts are made from forged steel or cast iron. Medium carbon
steels with percentage of carbon being between 0.25-o.45%

Cam Shaft
A camshaft is a rotating object which converts rotational motion to reciprocal motion.
Camshafts are used in internal combustion engines to operate the intake and exhaust valves.
Camshaft made mostly widely used martial is chilled cast iron or forged steel. They can handle
large mechanical lodes and have high wear resistance.

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Injector
The part which ensures injector of fuel inside the cylinder head at the right moment and at the
quantity for combustion and power. Injectors are made of carbon steel, stainless steel, brass,
titanium, PTFE, carbon, and other materials.

Thermostat valve
A thermostat is a component which senses the temperature of a physical system and performs
actions so that the system's temperature is maintained near a desired set point.

Oil Pump

The oil pump in an internal combustion engine circulates engine oil under pressure to the
rotating bearings, the sliding pistons and the camshaft of the engine.

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Fuel Pump
The purpose of the fuel pump is to push the fuel from the tank to the injectors

Flywheel
A flywheel is a mechanical device which uses the conservation of angular momentum to store
rotational energy; a form of kinetic energy proportional to the product of its moment of inertia
and the square of its rotational speed. standard weight Flywheel are composed of iron and billet
steel while lightweight flywheels are made with chromoly and aluminum.

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 Experiment No. 02
Name of the Experiment: Study of Internal Combustion (IC) Engines
Theory: A device that converts thermal energy to mechanical energy. The thermal energy is
produced from the combustion of hydrocarbons in presence of oxygen in exothermic reaction
commonly called Combustion Reaction. The Second law of thermodynamics is the basis of all
types of heat engine. The law states that “Heat flows from regions of higher temperature to
regions of lower temperature, but it will not flow natural the other way”.
Based on the location of combustion engines are of two types:
External Combustion Engine: Product of combustion is not the working fluid. Combustion
occurs outside of the cylinder. Example: Steam Engine, Sterling Engine
Internal Combustion Engine: Products of combustion works as the working fluid and the
combustion takes place inside the cylinder. Example: Petrol Engine, Diesel engines, Biofuel
engine and so on.
Basic Engine Terminology:

1. Bore: The nominal inside diameter of the engine cylinder is called bore.
2. Top Dead Centre (T.D.C): Position of the crankshaft when the piston is at the topmost
position.
3. Bottom Dead Centre (B.D.C): Position of the crankshaft when the piston is at the
bottommost position.
4. Stroke (L): The distance travelled by the piston from the TDC to BDC is called the
stroke. It is the maximum distance that the piston can travel in the cylinder. It is equal
to twice the radius of the crank.
5. Clearance Volume: Extra headroom above the piston head from the when it is at the
Top Dead Centre. It is denoted as Vc.
6. Piston Displacement: Volume covered in between TDC and BDC of piston
displacement. This is the combustion chamber of the heat engine.

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 7. Total Piston Displacement or Engine Capacity: Capacity of engine found by
multiplying the number of pistons with Piston Displacement.
8. Swept Volume: It is the volume which is swept by the piston. The difference between
total volume and clearance volume is knows as the swept volume.
9. Compression ratio: The ratio of maximum volume to minimum volume of cylinder is
known as the compression ratio. It is between 8-12 for SI engine and between 12-24 for
CI engine.
Mathematically it is defined as r = (Vs + Vc) / Vc or (Total volume / Clearance Volume)
10. Mean Effective Pressure: The average pressure acting upon the piston is known as mean
effective pressure. It is given by the ratio of the work done by the engine to the total
volume of the engine.
11. Indicated Power (IP): The power developed within the engine cylinders.
12. Brake Power (BP): The actual power delivered at the crankshaft. It is measured with a
dynamometer and is expressed in kilowatts. It is always less than Indicated power due
to frictional and pumping losses in cylinders and the reciprocating mechanism.
13. Engine Torque: It is the force of rotation acting about the crankshaft axis at any given
instant.
• Engine with high brake power and low torque -> Vehicle is easy to accelerate
but high speed is difficult to maintain.
• Engine with low brake power and high torque -> Vehicle is difficult to
accelerate but high speed is easy to main
How Engine Operates:
In a four stroke SI engine power is produced in a four-stage operation. They are:
1. Intake Stroke: Piston moves downwards creating a vacuum inside the combustion
chamber. When the intake valve opens, atmospheric pressure forces the air-fuel mixture
inside the combustion chamber.
2. Compression Stroke: Intake valve is closed; piston moves upwards compressing the air-
fuel mixture to around 1/8th of its original volume.
3. Power Stroke: The ignition system provides the spark in the spark plug. As a result the
compressed fuel mixture ignites with a large explosion. The resulting explosion causes
sudden expansion of the air-fuel mixture which forces the piston to move downward
creating the power necessary to drive the wheel of the vehicle.
4. Exhaust Stroke: The exhaust valve opens and the piston moves upwards. This upward
movement forces the burnt gases out of the cylinder. We see that for two complete
rotation of the crankshaft power is produced on.
Engine Classification:
Heat engine can be classified by many categories. They are
i. Number of cylinders: V4, V6 etc. engines ii. Arrangement of Cylinder: Inline, V-type,
Opposed.
ii. Arrangement of Valves: Overhead camshaft, pushrod camshaft, valveless.

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 iii. Type of cooling: Water-cooled, Air-cooled v. Number of strokes per cycle: 2-stroke,
4-stroke
iv. Type of fuel used: Gasoline, Diesel, Ethanol, CNG.
v. Method of Ignition: Spark Ignition, Self or Compression Ignition.
vi. Firing Order: For four cylinder - 1-2-4-3, 1-3-4-2
Comparison of Petrol and Diesel Engine:

1. In Petrol engine (Spark Ignition Engine) mixture of air and petrol is charged into the
cylinder and compressed but in the case of Diesel engine (Compression Ignition) only
the air is compressed.
2. For SI engine compression ratio is in between 8-12 whereas the compression ratio for
CI engine is between 12-24. The result is higher thermal efficiency and fuel savings in
diesel engine when compared to a SI engine of similar specifications.
3. No throttle valve is present in the passage of diesel engine which results in higher
volumetric efficiency. Diesel is also cheaper than petrol
4. There is no spark plug, carburetor, etc parts in a CI engine. CI engines typically have
common rail injection with modern ones having the capability to control how much fuel
goes into each cylinder from the common injection rail very accurately.
5. SI engines have higher accelerating power whilst CI engines are typically used for its
high torque available at different engine operating condition
Diesel Engine Theoretical Efficiency
Since the compression and power strokes of this idealized cycle are adiabatic, the efficiency
can be calculated from the constant pressure and constant volume processes. The input and
output energies and the efficiency can be calculated from the temperatures and specific heats:
𝑄1 = 𝐶𝑃 (𝑇𝑐 − 𝑇𝑏 )

𝑄2 = 𝐶𝑣 (𝑇𝑎 − 𝑇𝑑 )
𝑄1 + 𝑄2
Efficiency, η = 𝑄1

It is convenient to express this efficiency in terms of the compression ratio rC = V1/V2 and the
expansion ratio rE = V1/V3.

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 Figure: Air standard diesel engine cycle
The efficiency can be expressed in terms of the specific heats and temperatures
𝐶𝑉 (𝑇𝑎 − 𝑇𝑑 )
η=1+
𝐶𝑃 (𝑇𝑐 − 𝑇𝑏 )

Now using the ideal gas law PV= nRT and γ = CP/CV, this can be written
1 𝑃𝑎 𝑉𝑎 − 𝑃𝑑 𝑉𝑑
η=1+
γ 𝑃𝑐 𝑉𝑐 − 𝑃𝑏 𝑉𝑏

Now using the fact that Va=Vd=V1 and Pc= Pb from the diagram
1 𝑉1 (𝑃𝑎 − 𝑃𝑑 )
η=1+
γ 𝑃𝑐 (𝑉3 − 𝑉2 )

Dividing the numerator and denominator by V1Pc

𝑃𝑎 𝑃𝑑
1 𝑃𝑐 − 𝑃𝑐
η=1+
γ (𝑟𝐸−1 − 𝑟𝐶−1 )

Now making use of the adiabatic condition PVγ = constant,

𝑃𝑎 𝑉2 γ 𝑃𝑑 𝑉3 γ
= =
𝑃𝑐 𝑉1 𝑃𝑐 𝑉1

The efficiency can be written

−γ −γ
1 (𝑟𝐸 − 𝑟𝐶 )
η=1−
γ (𝑟𝐸−1 − 𝑟𝐶−1 )

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 Experiment No. 03(a)
Name of the Experiment: Study of an Automotive SI Engine
Objectives:
a. Identification and studying functions of different engine components.
b. Disassembling the engine.
c. Reassembling the engine.
d. Testing the assembly procedure by starting the engine.
Report Writing: Identify the missing components of the following systems and briefly state
their functions.
1. Fuel supply system

2. Air intake and exhaust system

3. Lubricating oil system

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 4. Cooling water circuit

5. Spark Ignition system

6. The starting and Electrical Charging System

Assignment:
1. No of cylinder rings, their types and functions.
2. No of bearings, their types and functions.
3. No of valves and mention which one was bigger, why?
4. Location of thermostat in cooling water circuit.
5. No of pumps and their type.

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 Experiment No. 03(b)
Name of the Experiment: Dismantling and Assembling a Diesel Engine
Objective:
a) Identification and studying functions of different engine components.
b) Disassembling the engine.
c) Reassembling the engine.
d) Testing the assembly procedure by starting the engine.
Engine Specification:

Bore
Stroke
No of cylinder
Arrangement of cylinders
Cam shaft type
Injection type
Type of fuel pump

Procedure:
1. Study the engine in order to identify different components of it.
2. Dismantling
a. Drain out the lubricating oil and water.
b. Remove the head cover.
c. Remove fuel line (also disconnect at the injector)
d. Remove intake and exhaust manifold
e. Remove cylinder head cover
f. Remove rocker arm along with push rod.
g. Remove lub. oil line
h. Remove timer cover
i. Remove rear cover.
j. Remove piston

3. Draw the necessary schematic diagram and note the different types of bearing.
4. Assembling: Almost reverse the sequence of dismantling of followed during assembling.
5. Test the assembly procedure by starting the engine.

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Report Writing: Identify the missing components of the following systems and briefly state
their functions.
1. Fuel supply system

2. Air intake and exhaust system

3. Lubricating oil system

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 4. Cooling water circuit

5. Fuel Control System

Assignment: Provide following information regarding to your observation in the experiment.

1. No of cylinder rings, their types and functions
2. No of bearings, their types and functions
3. No of valves and mention which one was bigger, why?
4. Location of pump in cooling water circuit
5. Fuel injection type, no. of holes in each nozzle.
6. How you differ diesel engine from petrol engine.

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 Experiment No. 04
Name of the Experiment: A Study of Diesel Engine with Cut View Model.
Objective: To observe and study the constructional details, working principles and operation
of the Diesel Engine with Cut View Model Individual gears on Propeller Rotation.
Specifications:
Type: Four cylinders in line, four cycle fresh water-cooled diesel.
Displacement: 107 cu. in. Bore 3.125", Stroke 3.5".
Power: 37 hp at 3000 rpm (see power curve).
Compression Ratio: 22:1.
Weight: 474 lbs. basic engine. Add gear weight oppo- site page for 1.0.R. weight.
Fuel Injection Equipment: Distributor type fuel pump with mechanical governor and pintel
type injectors.
Cylinder Block: One-piece iron alloy casting with replaceable liners.
Cylinder Head: One piece iron alloy casting with renewable valve guides.
Crankshaft: Chrome molybdenum steel forging.
Main bearings: Three, replaceable, thin wall, lead bronze lined.
Camshaft: High duty cast iron.
Pistons: High silicon aluminum alloy.
Connecting Rods: Drop forged steel.
Lubrication: Eccentric lube oil pump, camshaft driven. Full flow spin-on lube oil filter.
Exhaust Manifold: Fresh water cooled, front or rear exhaust.
Cooling System: Closed circuit fresh water system. Fresh and raw water pumps, engine-
mounted.
Angle of Installation: 17° maximum.
Electrical System: 12-volt negative ground system with 55-amp alternator standard. Extra 55,
or 120 amp alternators available.
Installation Data: 11/2" IPS exhaust flange; 1/2" IPS raw water inlet; fuel inlet 1/4" tubing,
fuel return 3/16" tubing.

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 POWER CURVE

Standard Equipment
Fresh water cooling system with heat exchanger, surge tank and pumps, propeller shaft
coupling; clutch lever with lower extension for remote control where applicable; spin-on full
flow lube oil filter, lube oil cooler, sump pump and hose; engine-mounted secondary fuel oil
filter, fuel lift pump with hand primer, flexible hoses for fuel inlet and return, mechanically
governed fuel injection system; cold weather starting aid, mounted and piped; 12 volt, 55 amp
alternator with transistor regulator; plug-in engine pre-wiring including pre-wired start panel
with 10 foot cable; threaded 1/2" IPS exhaust flange; fully illustrated Instruction Manual and
Parts List; front or rear opening exhaust outlet.
Optional Equipment
High efficiency primary fuel filter; Hydro-Hush stainless steel water-lift muffler, water injected
exhaust elbow, flexible stainless steel exhaust section; sea water strainer, remote fresh water
expansion tank; remote lube oil filter, front-end lube oil fill; pre-wired all- electric instrument
panel, with 10-foot cable, pre-wired mechanical instrument panel with tachometer cable, extra
10 foot cable for instrument panel or starting panel; high temperature, low pressure alarm
system; extra 55, 120 amp alternators, engine-mounted; crankshaft-mounted accessory pulleys,
5", 6" or 7" diameter; flexible shaft coupling; special engine mounts, spare parts kits.
Transmission: See Individual gears on opposite page for Specifications and Propeller
Rotation.

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 Experiment No. 5
Name of the Experiment: A study of refrigeration cycle
Vapor Compression refrigeration
• Refrigerant under goes phase changes.
• Widely used method for air condition of building and automobiles.
• Refrigeration may be defined as lowering the temperature of an enclosed space by
removing heat from that space and transferring it elsewhere.

Figure: Typical single stage vapor compression refrigeration

• Vapor compression uses a circulating liquid refrigerant as the medium which absorbs
and removes heat from the space to be cooled and subsequently reject that heat
elsewhere.
• Enters compressor as – saturated vapor.
• Leaves compressor as –superheated vapor.
• Enters expansion valve as / leaves condenser as saturated liquid.
• In the expansion valve – abrupt reduction in pressure. It results in the adiabatic flash
evaporation of a part of the liquid refrigerant.
• In the evaporator the liquid + vapor mixture absorbs heat from the surrounding and
result in the evaporation of the liquid returning it to gaseous state whilst absorbing heat.
Pressure-Enthalpy Diagram (P-H Diagram)

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Saturated Liquid:
A liquid whose temperature and pressure are such that any decrease in pressure without change
in temp. causes it to boil.
Saturated Vapor:
A vapor that is about to condense.
Sub cooling liquid:
If is temp, of the liquid is lower than the saturation temp, for the existing pressure it is called a
subcooled liquid.
Superheated Vapor:
It is the type of vapor that is separated from the liquid drop lets follower by the addition of
additional heat and it is not able to condense.
Calculation formulae:
Actual work of compression wc = hR2 – hR1

Heating effect, qh = hR2 – hR3

Refrigerating effect, qc = hR1 – hR4

qc
Cooling Coefficient of Performance, (Cop)c = qh

qh
Heating Coefficient of Performance, (Cop)c = 𝑊𝑐

Subcooling degree, SC = Tsat_condensation – T3

Superheat degree, SH = T1 – Tsat_suction

Experiment (a): Demonstration and performance analysis of a vapor compression

refrigeration or heat pump cycle.
Aim
To learn the thermodynamic processes of a vapor compression refrigeration or heat pump cycle
and demonstrate it on a Pressure-Enthalpy chart.
Preparation
1. About 7 liters clean water (preferably de-mineralized or de-ionized) at about 20-23 OC
2. Pressure-Enthalpy chart for R134a
3. Pencil
4. Ruler
5. A suitable cloth to clean up water spills
6. Instead of items 2 - 4 TecQuipment’s integrated VDAS” can be used with a suitable
computer.

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Procedure
1. Fill the two water tanks up to the lower surface of the water tank’s top plate. Fresh water
must be used if the system has just been used for another experiment.
2. If not using VDAS”, create a blank result table similar to Table 1 below.

3. Make sure the unit is plugged in and the main switch on the left side of the control panel
is ON.
4. Turn the water pump ON using the pump switch on the control panel.
5. Wait until the water temperature between the two tanks is similar (TW1 - TW2).
6. Turn the compressor ON using the compressor switch on the control panel.
7. Leave the unit to run until the temperature difference between the two tanks is stable.
8. If not using VDAS” record the measured values as shown in Table 1.
9. Switch OFF the compressor and the pump.
10. The tanks Draining the Water.
Table No- 1

Parameter Symbol Experiment case with water pump “ON”

Compressor suction temperature (°C) TR1
Compressor discharge temperature (°C) TR2
TEV inlet temperature (°C) TR3
TEV outlet temperature (°C) TR4
Low-side pressure (bar) PLOW
High-side pressure (bar) PHIGH
Temperature difference between the two ∆TW
tanks BEFORE the compressor was
switched “ON” (°C)
Temperature difference between the two ∆TW
tanks AFTER the compressor was
switched ON (°C)

Results Analysis:
1. Convert gauge pressures (PHIGH, PLOW) into values of absolute pressure (PHIGH-ABS, PLOW
- ABS) as used in the Pressure-Enthalpy chart.
2. Plot the state points of the refrigerant on the Pressure-Enthalpy chart as follows:
• Point 1: use the measured values of TR1 and absolute pressure of the low-side (PLOW -
ABS)
• Point 2: use the measured values of TR2 and absolute pressure of the high-side (PHIGH-
ABS)
• Point 3: use the measured value of TR3 and the pressure of the condensation process
(equivalent to the absolute pressure of the high-side (PHIGH-ABS)
• Point 4: use the measured value of vaporization pressure (equivalent to the absolute
pressure of the low-side (PLOW - ABS) and the constant enthalpy of the expansion process
(hR3=hR4).

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 3. Draw lines to connect points 1-2, 2-3, 3-4 and 4-1 to achieve a complete refrigeration
cycle.
4. Determine the cycle performance by calculating the work of compression, the heating
effect, the refrigerating effect and the two heating and cooling COPs using formulas (6,
10, 12, 13, and 14) also the superheat and sub cooling degrees using formulas (15 and
16).
5. How does the water temperature of the two tanks change after the compressor is
switched ON?
6. How does this affect the cycle performance?

Experiment (b) — Performance comparison between actual vapor compression

refrigeration and reversed Carnot cycle

Aim:
To compare performance between an actual refrigeration or heat pump cycle with the reversed
Carnot cycle (i.e., an ideal refrigeration or heat pump cycle)
Preparation:
1. About 7 litres water (preferably de-mineralized or de-ionized) at about 20-23” C.
2. Pressure-Enthalpy chart for R134a.
3. Pencil.
4. Ruler.
5. A suitable cloth to clean up water spills.
6. Instead of items 2 - 4 TecQuipment’s integrated VDAS” can be used with a suitable
computer.
Procedure:
1. Make sure the unit is plugged in and the main switch is ON.
2. If another experiment has not been run immediately prior to starting this experiment, fill
the two tanks with water at 20-23”C and run the pump and compressor for 15 minutes.
3. Once the previous experiment is finished. Switch the compressor OFF and the pump.
Drain the tanks.
4. Turn the pump OFF once both tanks are completely drained.
5. Fill the two water tanks with fresh water at 20-23°C, up to the lower surface of the water
tank’s top plate.
6. Switch the pump ON and run the system until both tanks are at a similar temperature:
(TW1 - TW2).
7. Switch the pump OFF.
8. Switch the compressor ON.
9. If not using VDAS”, create a blank result table similar to Table 2.
10. Record the measured values as shown in Table 2.
Warning: Due to the maximum allowable working pressure of the refrigerant in the
condenser coil, do not heat the hot water tank to over 45” C.
11. Switch the compressor OFF and drain the tanks See Draining the Water.

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 Table No 2

Parameter Symbol Hot Water Tank Temperature Tw1' 40° C

Cold water tank temperature (°C) TW2
Low-side pressure (bar) PLOW
High-side pressure (bar) PHIGH
Suction-line temperature (°C) TR1
Discharge-line temperature (°C) TR2
TEV inlet temperature (°C) TR3
TEV outlet temperature (’C) TR4

Results Analysis:
1. Calculate the heating and cooling COPs of the refrigeration cycle as instructed in
experiment
2. Calculate the heating and cooling COPs of the reversed Carnot cycle using formulas (19)
and (20) with heat source temperature TA - TW2 and heat sink temperature TB- TW1
3. Compare COPs between the actual refrigeration cycle and the reversed Carnot cycle

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 Experiment No. 6
Name of the Experiment: Performance test of a high-speed Diesel Engine

Objectives:
a) Study the engine specification and performance parameter.
b) Do the performance test and measure Bhp, Bsfc and BMEP.
Engine Specification & Ambient Data:

Brand Name Lubrication

System
Model Cooling
Engine No. Exhaust
Country of Lub Oil Filter
Make
Manufacturer Fuel Filter
Rated Output Air Cleaner
Rated rpm Oil Press.
Indicator
No of Cylinder Coupling
Lub. Oil Used Starting
Fuel Used Dry Valve Temp.
Dynamometer Atm. Pressure
Rotation (ffs) Relative
Humidity

Engine Performance Test:

Calorific value of fuel, CL= 43.8 MJ/Kg
Coefficient of discharge of the orifice, Cd=O.6 Orifice diameter, d=0.0185 m
Gas constant for air, R= 287 Jkg-1K-1
Specific heat of air at constant pressure, CP=1004.5 J/Kg
Fuel Density= 840 kg/m 3
Engine capacity= 232cc
Ambient pressure, P= mbar= N/m

24 | N A M E 3 1 0
25 | N A M E 3 1 0
 Experiment No. 7
Name of the Experiment: Study of Diesel power plant of MIST
Objectives:
1. Identification and studying functions of different engine components
2. Write down the engine specification.
Engine specification:

Brand Name

Model Cooling

Engine No. Exhaust

Country of Lub Oil Filter

Make

Manufacturer Fuel Filter

Rated Output Air Cleaner

Rated rpm Oil Press.

Indicator

No of Cylinder Coupling

Lub-Oil Used Starting

Fuel Used Lubrication

System

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 Experiment No. 8
Name of the Experiment: Study of gas turbine cut model view.
Introduction
A gas turbine model, represents a pure jet engine. In this engine combustion causes expansion
of gas capable of producing useful work and thus cause jet propulsion. It consists of a
centrifugal flow compressor, axial flow power turbine, and annular combustor. gas turbine
engines that are commonly used in marine and aircraft propulsion as well as in industrial and
stationary power generation.
The following figure shows a model gas turbine.

Figure 1: Gas turbine

This gas turbine is made up of 4 sections and which are:
• Inlet part
• Compression part
• Combustion part
• Turbine and exhaust part
The turbine part is responsible for creating needed power output to run propeller. It also serves
to generate power for driving all other parts of the turbine and compressor. For it to produce
power, this gas turbine has to expand gas at high pressure, velocity and temperature and
transforms gas energy to mechanical energy available at the power shaft. The compressor is
used to provide a certain amount of air. It works by creating air to the engine and where it is
squeezed to generate high-pressure air needed in the turbine. Compressor works using
mechanical power from turbine that converts gaseous energy in form of temperature and
pressure. Gas turbine encounters frictional losses which makes it hard for the compressor to
provide all air required by turbine. As such, the turbine does not provide all the power required
by compressor. Therefore, it means energy has to be added to the air so as to supplement the
deficit. The combustion part is where energy is produced. This happens when fuel is burned
and fuel chemical energy transformed into gaseous energy at high temperature and air velocity.
The gaseous energy is then transformed into mechanical energy and used to drive output shaft

27 | N A M E 3 1 0
and compressor. Basically, the gas turbine consists of 4 cycles which are air intake, air
compression, combustion and expansion and exhaust.
The figure below shows cycles of a closed gas turbine on a T-S diagram.

Figure 2: Closed gas turbine T-S diagram

Gas turbine performance is depended on shaft horse power the engine produce sat certain
conditions. Most of jet engines have power ratings at 29.92 inches of mercury and 59°F. The
specific fuel consumption at a certain condition defines the engine efficiency. The efficiency
is determined by amount of air mass flow rate via the engine, operating temperatures,
compressor pressure ratio, and individual component efficiencies.

28 | N A M E 3 1 0
Gas Turbine Working Principle
The gas turbine works on the base of the Brayton cycle. During this cycle, the air-fuel mixture
is pressurized, burned, passed through a gas turbine, and discharged.
In the working cycle of a gas turbine, air uses as a working medium. A gas turbine works in
the following the stages:
1. Suction Process: First of all, the turbine sucks air into the compression chamber from
the atmosphere into the turbine and sends this air to the compressor.
2. Compression Process: As the air enters the compressor it compresses the air and
converts the air kinetic energy into pressure energy. After this, it converts the air into
high-pressure air.
3. Combustion Process: After the compression process, the compressed air enters
the combustion chamber. In the combustion chamber, an injector injects fuel into the
chamber, which mixes with the air. After mixing, the combustion chamber ignites the air-
fuel mixture. Due to the ignition process, the air-fuel mixture converts into high pressure
and high-temperature gases.
4. Turbine Section: As the combusted gas enters into the turbine section, some energy of
this gas transforms into mechanical energy, and some energy is exhausted. As the
combustion gas expands through the turbine, it rotates the turbine blades. The rotating
blades have a dual function: they run the compressor to draw in more air for operation
and also drive a gas generator connected with the turbine.

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