I.C ENGINE LAB. Performance of The Four Strokes Diesel Engine

1. 1
University of Baghdad
College of Engineering
Department of Mechanical Engineering
I.C ENGINE LAB.
Performance of The Four Strokes Diesel Engine
:‫االسم‬
-
‫حمزة‬ ‫مرزة‬ ‫حاتم‬ ‫عدي‬
:‫شعبة‬
-
‫أ‬
:‫المرحلة‬
-
‫الرابعة‬

2. 2
Equations:-
1-Braking power:
It’s just the regular power (P=W.T)
After cutting the losses
(It’s multiplied by (2𝜋/60) to convert the speed from r.p.m to red/s)
𝑃𝐵 =
2𝜋𝑁𝑇
60000
2-fuel mass flow rate (kg/hr)
𝑚
̇ 𝑓 =
𝑆×8×3.6
𝑡
3- Specific fuel consumption;
The amount of fuel consumed by a engine for each unit of power output
𝜌𝑎 =
𝑝𝑎
𝑅𝑇𝑎
4- Air/Fuel Ratio;
Is the amount of air needed(𝑚
̇ 𝑎) to burn (𝑚
̇ 𝑓) amount of fuel
𝐴𝐹𝑅 =
𝑚
̇ 𝑎
𝑚
̇ 𝑓
5- Air Density;
by using the ideal gas law we get this eqution
𝐴𝐹𝑅 =
𝑚
̇ 𝑎
𝑚
̇ 𝑓

3. 3
CALCULATION:
𝑃𝐵 =
2𝜋𝑁𝑇
60000
𝑃𝐵 =
2𝜋(1250)(6)
60000
= 0.785𝑘𝑤
𝑚
̇ 𝑓 =
𝑆×8×3.6
𝑡
𝑚
̇ 𝑓 =
830
1000
×8×3.6
59.7
= 0.4 𝑘𝑗/𝑘𝑔
𝑠𝑓𝑐 =
𝑚
̇ 𝑓×1000
𝑃𝐵
𝑠𝑓𝑐 =
0.4×1000
0.785
= 510.066
𝑔
𝑘𝑊ℎ
𝐴𝐹𝑅 =
𝑚
̇ 𝑎
𝑚
̇ 𝑓
𝐴𝐹𝑅 =
6.5
0.4
= 16.25
𝜂𝑣 =
𝑚̇ 𝑎
60×𝑁×𝜌𝑎×𝑉𝑠
𝜂𝑣 =
6 .5
60×1250×1.2×230×10−6 = 31.4%

4. 4
𝜂𝑏 =
𝑃𝐵×3600
𝑚
̇ 𝑓×𝐶𝑣
𝜂𝑏 =
0.785×3600
0.4×40850
= 17%
%𝑙𝑜𝑠𝑠 =
100 × (1 + 𝐴𝐹𝑅)(𝑇𝑒 – 𝑇𝑎 )
𝐶𝑣
%𝑙𝑜𝑠𝑠 =
100 × (1 + 16.25)(200 – 25 )
40850
= 7.38%
Test Number 1 2 3 4 5
a) Speed (Rev/min) 1250 1500 1750 2000 2250
b) Torque (Nm) 6 6 6 6 6
c) Brake Power (kW) 0.785 0.942 1.099 1.256 1.413
d) Fuel: Time for 8 ml (s) 59.7 53.1 49.2 42.4 3.2
e) Fuel mass flow rate
(kg/hr)
0.4 0.45 0.48 0.56 0.74
f)Specific fuel consumption
(g/kWh)
510.06 477.8 442.08 448.8 528.6
g) Air: mm H2O 6.5 13 15.5 14 17.5
h) Air mass flow rate
(kg/hr)
6.5 14.9 16.5 15.3 19
i) Air / fuel ratio 16.25 33.09 33.96 27.13 25.43
j) Exhaust temperature (°C) 200 215 233 248 256
k)Volumetric efficiency % 31.4 59.9 56.9 46.1 50.9
l) Brake thermal efficiency
%
17 18.4 19.9 19.6 16.6
m) % Heat loss exhaust 7.38 15.8 17.8 15.3 14.9

5. 5
As see from we can the graph above the more speed the
engine give the more braking power we need to stop it
0.785
0.942
1.099
1.256
1.413
y = 0.0006x
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 500 1000 1500 2000 2500
P
B
N
16.25
33.09 33.96
27.13
25.43
0
5
10
15
20
25
30
35
40
0 500 1000 1500 2000 2500
AFR
N

6. 6
510.06
477.8
442.8 448.8
528.6
0
100
200
300
400
500
600
0 500 1000 1500 2000 2500
SFC
N
31.4
59.9
56.9
46.1
50.9
0
10
20
30
40
50
60
70
0 500 1000 1500 2000 2500
𝜂v
N

7. 7
17
18.4
19.9 19.6
16.6
0
5
10
15
20
25
0 500 1000 1500 2000 2500
𝜂
b
N
200
215
233
248
256
y = 0.058x + 128.9
0
50
100
150
200
250
300
0 500 1000 1500 2000 2500
Te
N