Transcript Experiment #5 IC Engine - Rutgers School of Engineering

Experiment #4
IC Engine
Indicator Diagram
expansion
ignition
compression
exhaust
intake
The indicated work per cycle is computed from the area under the p-v
diagram
W N Work/power stroke rev./time 
P

Indicated power = i ni 
rev/power stroke
p
Brake power = indicated power -friction power
Pb = Pi-Pf

Experimental Apparatus
Throttle
Controls:
• Throttle setting
• Load valve
Instrumentation:
• Engine rpm
• Dynamometer pressure
• Fuel flow rate
• Cylinder head
temperature
• Oil temperature
Engine rpm
Objectives
• Using a single cylinder four stroke engine
• Mea sure engine power, rpm and fuel consumption at
difference throttle settings
• Plot relevant engine parameters as a function of engine
rpm and discuss the results
Engine Parameters
• Measured Brake power (W):
•
 p dynamomete r oil flow rate dynamomete r pressure 
Q
P 

b p
pump efficiency

m
fuel mass flow rate
Brake specific fuel consumption (kg/Nm): bsfc  P f  brake power
b
• Brake mean effective pressure (N/m2):
W P np brake power revolutions per power stroke
b b 
V
VN
displacement volume rev/time 
d
d
P brake power
Brake Torque (Nm):   Nb 
rev/time

bmep 
•
•

m
Fuel/Air mass ratio  F/A  f
a
m
Use p = 0.8

Engine Parameters (continued)
 n
m
ma
a p
mass
of
air
inducted/p
ower
stroke
Volumetric Efficiency = v   V  air density cylinder displaceme nt  
 V N
ai d
ai d
Effects of:
air friction
chocking
backflow, etc
v

Engine rpm
Conversion Efficiency:
Mechanical Efficiency
P
1
brake power 
b 
 

 H
f m
f HV fuel flow rate fuel heating value  bsfc H HV
P
m  b
P
i
Use HHV = 44 MJ/kg, and

Engine Parameters (continued)
 
bmep   vH  F 
HV aiA
f

 H
 (F/A)H
P  m
 m
HV
b f f HV f a
V  ApL
d
Sp  2LN
where

bmep Vd N bmep SpA p
  v  V N(F/A)H
HV
f
ai
d



np
np
2n p
Report
• For each throttle setting (1/4,1/2,3/4,full)
– Compute power, torque,sfc,mep, conversion efficiency
– Plot these computed quantities against engine rpm
– Discuss the results using references, and the relationships in
the notes
– Determine the most desirable engine speed for power,torque
and efficiency
• Compare the efficiencies with that of an idea Otto cycle
• Answer the question on connecting rod stress
PLEASE REPORT YOUR ANSWERS IN SI UNITS