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Performance at Constant Speed

The document describes a test conducted on a 4-stroke diesel engine to analyze its thermal, mechanical, and volumetric efficiencies at a constant speed of 1500 RPM. Key measurements taken include fuel consumption, torque, air flow, and temperature readings at different loads on the engine. Calculations are provided for determining the brake power, fuel consumption, frictional power, indicated power, and the various efficiencies. Results are to be tabulated and graphs plotted of efficiency versus brake power. The aim is to evaluate the engine's efficiencies at a constant speed.

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319 views6 pages

Performance at Constant Speed

The document describes a test conducted on a 4-stroke diesel engine to analyze its thermal, mechanical, and volumetric efficiencies at a constant speed of 1500 RPM. Key measurements taken include fuel consumption, torque, air flow, and temperature readings at different loads on the engine. Calculations are provided for determining the brake power, fuel consumption, frictional power, indicated power, and the various efficiencies. Results are to be tabulated and graphs plotted of efficiency versus brake power. The aim is to evaluate the engine's efficiencies at a constant speed.

Uploaded by

purnachand ra
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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I.

C ENGINE PERFORMANCE TEST ON A 4-S CI ENGINE AT


CONSTANT SPEED

AIM:

To conduct performance test on a 4-stroke diesel engine at constant speed and to


find the thermal, mechanical and volumetric effeciencies.

DESCRIPTION:

The test rig consist of 2 – cylinder, 4-stroke diesel engine to be tested for
performance test is compiled to AC generator with swinging field facility and with
spring balance and torque arm. The arrangement is spring balance made for the
following measurements of the setup.
1. The rate of fuel consumption is measured by using pipette reading against
known time.
2. The torque on the engine is measured by spring balance with the torque arm.
3. The air flow is measured by manometer connected to air box.

SPECIFICATIONS:

Type : 2 cylinder, 4 stroke diesel engine compression ignition


Make : Kirlosker
Rated Power Output : 15 HP, 1500 RPM
Ac Generator Capacity : 10 KVA (max), 440V, 50Hz, 3phase
Bore and Stroke : 87.5mm X 110 mm
Compression Ratio : 17.5:1

PROCEDURE:

1) Start the engine by using hand cranking.

2) Keep the loading switches in off position.

3) The engine is set to the speed of 1500RPM (constant speed)

4) Apply load to the AC generator by switching ON the loading switches.

5) Allow sometime so that the speed stabilizes.


6) Now take down swinging field spring balance reading, rotometers reading and
temperature reading.

7) Repeat the procedure for different loads.

8) Tabulate the readings in the enclosed sheet.

CALCULATIONS:

1. BRAKE POWER (BP)……….Kw

2𝜋𝑁𝐸𝑟
BP=
60,000
Where, N = Speed of the engine in RPM
E = Force in N
r = Radius of brake drum = 0.3m

2. TOTAL FUEL CONSUMPTION (TFC)………Kg/hr

TFC = fuel consumed in cc X density of diesel X3600


1000 X T

density of diesel = 0.85


T = time taken for consumption of 10 ml of diesel

3. SPECIFIC FUEL CONSUMPTION(SFC)……..Kg/Kw-hr

SFC = TFC/BP

4. FRICTIONAL POWER …………Kw

From the graph between brake power and total fuel consumption, the
frictional power is found by Willan’s line method.
5. INDICATED POWER (IP) …….. kW

= Brake power + Frictional power(Power loss)

6. MECHANICAL EFFICIENCY

= BP ×100%
IP

7. SWEPT VOLUME

Vs = Π d2 X L X N X 60 ………. m3/hr
4 2
where, d = dia of bore = 87.5 mm
L = length of stroke = 110 mm
N = Speed of the engine in RPM.

8. ACTUAL VOLUME

Va = Cd X A X √2gHa X 3600 ……. m3/hr

where, Cd = coefficient of discharge=0.62


A = Area of Orifice = Π d2
4
d = Dia. of Orifice = mm
Ha = Difference in Manometric head in terms of air = ρw × Hw
ρa
ρw = density of Water = 1000 kg/m3
ρa = density of Air = 1.2 kg/m3
Hw = Difference in Manometric head in terms of water = H1+H2

9. VOLUMETRIC EFFICIENCY

ŋv = VA X 100 ……….%
VS

10. BRAKE THERMAL EFFICIENCY

ŋbth = BP X 3600 X 100 ……….%


Tfc X cv

where , cv = calorific value of petrol = 42300 kJ / kg.


BP = Brake Power in kW.

GRAPHS:

BP Vs brake thermal efficiency,


BP VS mechanical efficiency.

RESULT:

Performance test at constant speed on twin cylinder CI engine was conducted and
the mechanical efficiency and thermal efficiency are evaluated.
TABULAR COLUMN:

s.no speed loading swinging air fuel energy temperature


in in Kw field consumption consumption meter points
rpm spring in mm of in cc/mm reading
force in water (10ml/sec) time in T1 T2 T3
N seconds
for 5
revs

TABLE OF CALCULATIONS:

S.No B.P TFC SFC Ma I.P ηmech ηvol ηbth


KW Kg/hr Kg/kw- Kg/min KW (%) (%) (%)
hr

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