for better understanding of internal combustion engines

1. Power and its
Measurements
Laboratory Exercise No.2
AENGR 411: Farm Power and Energy Resources

2. Bauzon, Reynaldo, Jr.
Diaz, Loieji
Echanez, Marc Ren-ren
Vela, Ma. Lourdes Maureen
Power and its Measurements

3. Power is the rate at which work
is done, it considers the length of
working hours or days. There are
factors that is affecting the power
such as mass, momentum, inertia,
torque, work and energy. There are
also ways to measure those factors.
I. INTRODUCTION

4. a. To measure the power delivered by
an internal combustion engine
b. To understand the exact technical
meaning of power as well as its
measurement
c. To know the different factors
related to the input/output of an engine
d. To know the factors affecting the
operation efficiencies of an internal
combustion engine
II. OBJECTIVES

5. a. Discussion of the following:
i. Mass
ii. Inertia
iii. Momentum
iv. Work
v. Torque
vi. Energy
vii. Power
viii. Pferdestarke
III. PROCEDURES

6. b. Discussion of the following and
illustration how each are determined:
i. Indicated horsepower
ii. Brake horsepower
iii. Friction horsepower
iv. Rated horsepower
v. Drawbar horsepower
III. PROCEDURES

7. 1. Mass
- is the measurement of how much
matter there is into something
- is sometimes dependent on the
size of the object, but still there is
exception like in the balloon, even it
gets bigger and bigger its mass will
stay the same.
IV. RESULTS AND DISCUSSION

8. 2. Inertia
- the resistance of any physical
object to any change in its state of
motion, it includes change in speed,
direction and state of rest
- the tendency of an object to
keep moving on a straight line at
constant velocity
IV. RESULTS AND DISCUSSION

9. 3. Momentum
- the product of mass and velocity
- term applied to a body in motion
- dimensionless
IV. RESULTS AND DISCUSSION

10. 4. Work
- an activity involving mental and
physical effort in order to achieve
a purpose or result
- done if a force is applied to a
body and caused it to change its
state of motion or if it is in motion,
its rate or direction of travel is
changed
IV. RESULTS AND DISCUSSION

11. 4. Work
work = force x distance
IV. RESULTS AND DISCUSSION

12. 5. Torque
- is a twisting force that tends to
cause rotation
Torque = force x distance
IV. RESULTS AND DISCUSSION

13. 6. Energy
- the capacity of a body of doing
work
- grouped into two distinct
classes, potential energy and
kinetic energy
IV. RESULTS AND DISCUSSION

14. 7. Power
- the rate at which work is done
- which rate is given in seconds,
then power is considered as foot-
pounds per second
Power = work ÷ time
IV. RESULTS AND DISCUSSION

15. 8. Pferdestarke
- from German words “Pferde” +
“Stärke”
- calque of horsepower
- approximately equal to 735.5
watts
IV. RESULTS AND DISCUSSION

16. 9. Indicated Horsepower (Ihp)
- the power generated in the
cylinder and received by the piston
Ihp = PLANn/(33,000x2) for 4SCE
Ihp = PLANn/33,000 for 2SCE
where: P=mean effective pressure, psi
L=length of piston stroke, ft
A=area f cylinder, sq. in
N=rpm
n=number of cylinders
IV. RESULTS AND DISCUSSION

17. 9. Indicated Horsepower (Ihp)
IV. RESULTS AND DISCUSSION
- it is essentially a
measure of the
total potential
horsepower the
engine is capable of
developing

18. 10. Brake Horsepower (Bhp)
- Brake or belt horse power
- indicated the actual usable
horsepower delivered at the engine
crankshaft
- it does not remain constant with
changes in engine speed
IV. RESULTS AND DISCUSSION

19. 10. Brake Horsepower (Bhp)
Bhp = 2∏r (torque x rpm) / 33,000
= (R x L x W) / 5252
where: R = engine rpm or speed
L = length from center of flywheel to
the point where beam presses on
the scale, ft.
W = force on scale due to friction, lbs.
1hp = 33,000 ft-lb/min
IV. RESULTS AND DISCUSSION

20. 10. Brake Horsepower (Bhp)
IV. RESULTS AND DISCUSSION
Force, lb.
Distance, ft.
Torch wrench
Rotating crankshaft
Bhp = 2∏r (torque x rpm) / 33,000

21. 10. Brake Horsepower (Bhp)
IV. RESULTS AND DISCUSSION

22. 11. Friction Horsepower (Fhp)
- part of the indicated horsepower lost
because of the drag of engine parts
rubbing together
- actual loss will vary with engine design
and use but will generally run about 10%
Fhp = Ihp - Bhp
IV. RESULTS AND DISCUSSION

23. 11. Friction Horsepower (Fhp)
IV. RESULTS AND DISCUSSION
- Friction horsepower
is determined by
subtracting
crankshaft Bhp from
Ihp

24. 12. Rated Horsepower (Rhp)
- the amount of power that the
manufacturer states an engine will
create at a specified engine rpm
- generally, 80% of its maximum brake
horsepower
IV. RESULTS AND DISCUSSION

25. 12. Rated Horsepower (Rhp)
IV. RESULTS AND DISCUSSION
As a general rule, never load an
engine to more than 80% of it’s highest
Bhp rating. For example, if a job requires
a horsepower loading of 8hp, you would use
an engine with at least a 10hp rating.
Then, the load would be no more than 80%
of the engine’s maximum hp.

26. 13. Drawbar Horsepower (Rhp)
IV. RESULTS AND DISCUSSION
- power developed at the hitch or
drawbar and available for pulling or
similar tractive effort
Dhp = (force, lb x speed, mph) / 375

27. To better understand and appreciate an
internal combustion engine, knowledge about
following must be considered:
- technical meaning of power as well as its
measurements
- different factors related to the
input/output of an engine
- factors affecting the operation efficiencies
- measurement of the power it can deliver
V. CONCLUSION

28. VI. REFERENCES
Print-outs
• Internal Combustion Engine Fundamentals. John B. Heywood.
McGraw-Hill, Inc. USA. 1988
• Basic of Engine Operations. The Goodheart Willcox Co.,Inc
• AENGR411lecture handout. Emmnuel Sicat.2016
Online
• http://www.slideshare.net/amanina_mal/agriculture-
engineeringchptr15
• http://en.wikipedia.org/wiki/
Others
• Microsoft Student 2008 Encarta Encyclopedia

29. a. Define horsepower and explain the origin of
the units’ actual value.
- horsepower(hp) is a unit
measurement of power
- the term horsepower was adopted
by Scottish engineer James Watt
to compare the output of steam
engines with the power of draft
horses
VII. SUPPLEMENTAL QUESTIONS

30. a. Define horsepower and explain the origin of
the units’ actual value.
VII. SUPPLEMENTAL QUESTIONS
1hp = 550 lb-ft/s
= 745.7watts

31. b. A 10-hp robin gasoline engine is to be used as
a prime mover for a single spindle hand tractor.
If the average load will not exceed 80% how
many liters of fuel will be consumed for an
average of an 8-hr day operation and how much
if fuel cost ₱ 49.95/L? compare this with a
diesel engine of the same hp rating with fuel
costing ₱ 29.95/L. heating value of the fuel is
10,500 Kcal/kg. Specific fuel consumption of
diesel and gasoline engines are 0.45 lb/hp-hr and
0.7lb/hp-hr respectively. Specific weights are
6.2 lb/gal and 7.2lab/gal for gasoline and diesel
fuel, respectively.
VII. SUPPLEMENTAL QUESTIONS

32. b.
VII. SUPPLEMENTAL QUESTIONS

33. c. A four cylinder, four stroke cycle engine by 3
by 4 in. cylinder, developed 19 hp at
1650rpm. Assuming a mechanical efficiency
of 85%, compute the IHP and MEP.
VII. SUPPLEMENTAL QUESTIONS

34. d. Compute the
thermal
efficiency of
the engine in
problem b
when it
consumed 47
lbs of gasoline
in a 4hr test.
VII. SUPPLEMENTAL QUESTIONS

35. e. A tractor with 9 in.
pulley is belted to a
prony brake having
a 24 in. pulley. If a
engines pulley speed
is 950 rpm, the
brake arm length is
54 m. and the load
in scale is 60lbs.,
what is the hp
developed?
VII. SUPPLEMENTAL QUESTIONS

36. f. Calculate the drawbar hp requires to pull a
plow with three 14in. Bottoms a rate of
3.25mph. If the draft is 8 lbs per sq.in. Of
furrow section and the depth of the cut is 7
in.
VII. SUPPLEMENTAL QUESTIONS

37. g. A Kubota engine is marked 6ps at 2400 rpm.
How many hp is it? What is its maximum
bhp?
VII. SUPPLEMENTAL QUESTIONS

38. h. A 10 hp single cylinder four cycle engine
consumes 3 L/hp of fuel. What is its
thermal efficiency? If fuel costs P40.00/L
how much will it consume for an 8-hr day
operation? It is diesel or gasoline engine?
Why so?
VII. SUPPLEMENTAL QUESTIONS

39. Thank you!
Power and its Measurements