Performance Evaluation of
Underground Mine Diesel
Engine Exhaust Insulation
Products
John Stekar
Bob Mojaverian
Catalytic Exhaust Products Limited MDEC
Presentation
October 2009
Abstract
Product Description
Procedure
Charts
Conclusion
Abstract
The use of diesel engine exhaust insulation products are widespread and
increasing in mobile underground mining equipment
applications. Diesel engine exhaust insulation products minimize
engine exhaust heat energy loss which can improve the oxidation
performance of diesel oxidation catalysts and diesel particulate
filters. In addition the passive regeneration performance of diesel
particulate filters can also be improved through the use of diesel engine
exhaust insulation products. Several types of diesel engine exhaust
insulation products are currently offered by a variety of
manufacturers. Very little published information is available concerning
the thermal properties and performance of diesel engine exhaust
insulation products.
In this technical paper 4 different types of diesel engine exhaust insulation
products provided by the same vendor are installed onto a 33 kW diesel
generator set and are evaluated based on ISO 8497. Each diesel
engine exhaust insulation product was installed onto an identical engine
exhaust pipe which was instrumented with 6 thermocouples attached to
an 8 channel Omega TC-08 datalogger. The thermal insulation
performance, heat transfer, insulation surface temperatures and rock
impact damage to the surface of insulation are tested and reported. In
addition the sound attenuation of each type of diesel engine exhaust
insulation was tested and evaluated.
Product Description
Insulation type CEP STD:
Outer layer
Gray color
silicone impregnated fiberglass
outer cover
Temperature limit of 500 ºF (260
ºC).
Middle layer
Fiberglass
Temperature limit of 1200 ºF (649
ºC).
Inner layer
Steel mesh (304)
Temperature limit of 1200 ºF (649
ºC).
Insulation type CEP II:
Outer layer
Red color
Silicone impregnated fiberglass
Temperature limit of 600 ºF (316
ºC).
Middle layer
Calcium-Magnesium-Silicate
(CMS) wool
Temperature limit of 1800 ºF (982
ºC).
Thin sheet of stainless steel 321
Inner layer
Steel mesh (304)
Temperature limit of 1200 ºF (649
ºC).
Insulation type CEP III:
Outer layer
304 stainless steel knitted wire
mesh
Stainless steel laminated
fiberglass
Temperature limit of 932 ºF (500
ºC).
Middle layer
Calcium-Magnesium-Silicate
(CMS) wool
Temperature limit of 1800 ºF (982
ºC).
Thin sheet of stainless steel 321
Inner layer
304 Stainless steel knitted mesh
Temperature limit of 1200 ºF (649
ºC).
Insulation type CEP Hard Coated
(HC):
Outer layer
Black color
Composite fiber
Inner layer
High alumina ceramic fiber
Temperature limit of 2300 ºF
(1260 ºC).
Exhaust Pipe Insulation Test Layout
Procedure
The exhaust pipe of a diesel genset was wrapped with 4
different types of removable insulation blanket.
Six sensors were installed on an exhaust pipe insulation as
shown in the previous slides.
Two extra sensors (T7 &T8) were set to measure ambient
temperature.
Temperatures measured in following steps: with engine off,
while engine running with zero load, load increased to 36%,
then 72% and back to 36%, zero load, and finally
measurement continued for the last stage after engine
turned off. The temperature of exhaust gas inside the pipe
was measured at Inlet (T5) and outlet (T6) and subtracted
to find the heat loss. The temperature of insulation inner
layer (T2 , hot side) and outer layer (T1, cold side) were
measured and subtracted to evaluate heat retention.
Temperature sensors connected to OMEGA TC-08 Datalogger
Load Bank
Exhaust pipe with no insulation installed
Exhaust gas temperature
measurement at outlet
(T6)
Exhaust Pipe with no insulation - Temperature v.s. Time
400
T1 Insulation cold side-outlet
300
T3 Insulation cold side-inlet
T4 Insulation hot side-inlet
36% load
36% load
T5 Inlet gas
T6 Outlet gas
250
T7 Ambient
T8 Ambient
200
0% load
0% load
150
100
50
Time [Min]
125
122
118
115
112
109
106
102
99.2
96
92.8
89.6
86.4
83.2
80
76.8
73.6
70.4
67.2
64
60.8
57.6
54.4
51.2
48
44.8
41.6
38.4
35.2
32
28.8
25.6
22.4
19.2
16
12.8
9.6
6.4
3.2
0
0
T [deg C]
T2 Insulation hot side-outlet
72% load
350
Exhaust pipe installed with CEP II insulation
T1 sensors installed on surface of CEP II insulation near outlet
Pictures showing sensor T3 installed on the surface of CEP II
Surface temperature
measurement
(T3)
Gas inlet temperature
measurement
(T5)
Sensor T2 installed on the pipe surface (under CEP II insulation)
near the outlet
Sound level measurement, CEP II insulation, near the inlet
Exhaust pipe + CEP II insulation, Temperature (deg C) vs. Time (sec)
Exhaust Pipe+CEPII Insulation - Temperature v.s. Time
T1 Insulation cold side-outlet
400
72% load
T2 Insulation hot side-outlet
350
T3 Insulation cold side-inlet
T4 Insulation hot side-inlet
36% load
36% load
T5 Inlet gas
T6 Outlet gas
250
T7 Ambient
T8 Ambient
200
0% load
0% load
150
100
50
0
0
3 .4
6 .8
1 0 .2
1 3 .6
17
2 0 .4
2 3 .8
2 7 .2
3 0 .6
34
3 7 .4
4 0 .8
4 4 .2
4 7 .6
51
5 4 .4
5 7 .8
6 1 .2
6 4 .6
68
7 1 .4
7 4 .8
7 8 .2
8 1 .6
85
8 8 .4
9 1 .8
9 5 .2
9 8 .6
102
105
109
112
116
119
122
126
129
133
136
139
143
146
150
T [d e g C ]
300
Time [Min]
Picture of exhaust pipe installed with CEP III insulation
450
Exhaust Pipe+CEPIII Insulation - Temperature v.s. Time
72% load
400
T1 Insulation cold side-outlet
T [d eg C ]
350
300
T2 Insulation hot side-outlet
T3 Insulation cold side-inlet
36% load
T4 Insulation hot side-inlet
250
T5 Inlet gas
200
150
36% load
T6 Outlet gas
0% load
T7 Ambient
T8 Ambient
100
50
5
11
17
22
28
33
39
45
50
56
61
67
73
78
84
89
95
149
155
161
166
172
177
183
189
194
200
205
211
217
222
228
233
239
245
250
0
Time [Min]
Picture of exhaust pipe installed with CEP STD insulation
Pictures showing sensor T3 installed on the surface of CEP STD
Surface temperature
measurement
(T3)
Exhaust Pipe+CEP STD Insulation - Temperature v.s.
Time
T1 Insulation cold side-outlet
72% load
400
T2 Insulation hot side-outlet
T3 Insulation cold side-inlet
350
36% load
36% load
T5 Inlet gas
T6 Outlet gas
250
T7 Ambient
200
0% load
0% load
T8 Ambient
150
100
50
0
0
3 .4
6 .8
1 0 .2
1 3 .6
17
2 0 .4
2 3 .8
2 7 .2
3 0 .6
34
3 7 .4
4 0 .8
4 4 .2
4 7 .6
51
5 4 .4
5 7 .8
6 1 .2
6 4 .6
68
7 1 .4
7 4 .8
7 8 .2
8 1 .6
85
8 8 .4
9 1 .8
9 5 .2
9 8 .6
102
105
109
112
116
119
122
126
129
133
136
139
143
146
150
T [d e g C ]
300
T4 Insulation hot side-inlet
Time [Min]
Picture of exhaust pipe installed with CEP HC insulation
Exhaust Pipe+CEP HC Insulation - Temperature v.s. Time
400
72% load
T1 Insulation cold side-outlet
T2 Insulation hot side-outlet
350
T3 Insulation cold side-inlet
300
36% load
T4 Insulation hot side-inlet
T5 Inlet gas
250
T6 Outlet gas
200
0% load
0% load
150
T7 Ambient
T8 Ambient
100
50
0
0
3
7
10
14
17
20
24
27
31
34
37
41
44
48
51
54
58
61
65
68
71
75
78
82
85
88
92
95
99
102
105
109
112
116
119
122
126
129
133
136
139
143
146
150
153
T [d eg C ]
36% load
Time [Min]
Surface temperature Insulation evaluation
The chart for surface temperature (measured with T1
sensor) vs. insulation type shown on the next two
slides. The chart shows that the skin (cold side)
temperature of CEP III has the lowest value (101
ºC) compare to the other types of insulation (108 to
114 ºC). Therefore CEP III is the best insulation in
terms of surface temperature and safety. Note that
the Values lag behind load change due to
insulation resistance. It has a delay in reaching to
the maximum temperature during loading of the
engine, and it has a delay in cooling off during
unloading of the engine, therefore as shown in the
chart 36% load shows higher heat than 72%.
Surface Temperature vs Insulation Type
Engine off
No Load
36% Load
72% Load
36% Load
No Load
Engine off
216
260
250
144
189
38
73
39
47
50
59
54
47
53
80
75
77
76
70
56
50
25
22
23
31
38
109
111
102
101
87
88
100
108
102
114
108
150
32
Temperature (deg C)
200
0
CEP STD
CEP II
CEP III
Engine Load
CEP HC
Baseline (pipe only)
Surface Temperature vs. Engine Load
No Insulation
CEP STD
250
CEP II
CEP III
CEP HC
260
216
189
T em p eratu re (d eg C )
200
144
150
109
108
102 102
94
100
70
50
25
32
23
31
38 39
48 47
56
114
108 111
95
75
88
76
71
80
73
58
38
53 58 50
22
0
Engine off
No Load
36% Load
72% Load
Engine Load
36% Load
No Load
Engine off
Insulation Heat Retention Evaluation
On the next two slides, the heat retention
was calculated by subtracting T1 from T2.
It represents pipe surface temperature (hot
side) minus insulation surface (cold side)
temperature. As shown in next slide, CEP
III has the highest heat retention (245 ºC),
than CEP II, CEP HC, and CEP STD.
Heat Retention vs. Insulation Type
Engine off
No Load
36% Load
72% Load
36% Load
No Load
Engine off
225
245
250
167
155
155
98
92
63
67
75
78
85
91
100
99
106
110
118
127
142
150
15
19
32
50
CEP STD
CEP II
CEP III
Engine Load
4
5
7
CEP HC
0
0
0
0
0
5
8
10
Temperature (deg C)
158
171
175
200
Baseline (pipe only)
Heat Retention vs. Engine Load
No Insulation
CEP STD
CEP II
CEP III
CEP HC
245
250
225
T e m p e ra tu re (d e g C )
200
158155
142
150
118
110
100
91 92
100
155
171175
167
127
106
98
67
63
78
75
50
0
85
32
0
10
15
0
Engine off
0
7
5
No Load
19
8
36% Load
5
72% Load
Engine Load
4
36% Load
0
No Load
Engine off
Heat loss inside exhaust pipe
On the next slide the heat lost was calculated by
subtracting exhaust gas temperature inside the
pipe at inlet from the value at the outlet side, or
T5 minus T6.
The lower the value, means lower heat loss, and
therefore a better insulation. CEP III, CEP II and
CEP STD are almost performed similar and
show lower values compare to CEP HC.
Therefore all three are acceptable in terms of
heat loss prevention.
Heat Loss vs. Insulation Type
Engine off
No Load
36% Load
72% Load
36% Load
No Load
Engine off
62
70
70
54
54
55
60
41
32
32
35
35
39
40
25
16
11
0
5
6
8
9
10
0
CEP STD
CEP II
CEP III
Engine Load
CEP HC
Baseline (pipe only)
15
19
19
17
18
20
18
20
20
22
26
26
27
30
16
Temperature (deg C)
46
50
Impact Test
In this test 15.87 kg weight was dropped
from a height of 4 feet on each insulation
while strapped to the exhaust pipe.
CEP III, CEP II and CEP STD shows no
visible damage to the surface of the
insulation after the drop test. CEP HC was
dented (about 0.25” deep).
CEP HC with dent after the impact
CEP STD, II & III no visible
permanent damage to the
insulation after the impact
Sound Level Measurement
Sound level measured 26” away from the insulated exhaust pipe. It shows 1-3 dBA
Improvement compare to pipe with no insulation. The sound measurement device
was exposed to direct engine and other environmental noise.
Sound level vs. Engine Load
No Insulation
Sound Level (dBA, SLOW)
100
93 93 93
CEP STD
90 91
95 94 95
92 93
CEP II
96 96 96 95
CEP III
CEP HC
94 94 93 94 93 93 93 92 93 92
91
80
60
58
55 53
60
49 51 48 47 48
50
40
20
0
Engine off
No Load
36% Load
72% Load
Engine Load
36% Load
No Load
Engine off
Oil Absorption Test
Each insulation was submerged in oil for
an hour and weight before and after, the
result is shown as % gain over the original
weight:
CEP STD 75% (highest oil absorption)
CEP II
71%
CEP III
64%
CEP HC 33% (lowest oil absorption)