Don't trust the data for some errors were arrived during the experiment. Let this be a reference for your calculations, format, etc.

1. HEAT LOSS IN BARE AND LAGGED PIPES
ELECCION, NICELY JANE R.
Department of Chemical Engineering
College of Engineering and Architecture
Cebu Institute of Technology – University
N. Bacalso Ave., Cebu City 6000
This experiment aims to determine the convection coefficient hc at various temperatures
from different surfaces namely bare, silver – chrome painted, paint, and 85% magnesia
insulated pipes, and to determine its corresponding lagging efficiency. The convection
coefficient of the various bare and lagged pipes are as follows: 2.12366 Btu/hr ft ˚F for
painted pipe, 2.11972 Btu/hr ft ˚F for bare pipe, 2.27068 Btu/hr ft ˚F for pipe covered with
silver-chrome paint, and 1.62058 Btu/hr ft ˚F for 85% pipe insulated with magnesia. Their
lagging efficiencies with respect to the bare pipe are as follows: approximately 0.94%
using the heat loss and 0.90% using the condensate collected in paint pipe, 40.6% using
the heat loss in silver-chrome painted pipe and 38% using the condensate collected in
silver-chrome painted pipe and 65.5% using the heat loss and 31% using the condensate
collected in 85% Magnesia insulated pipe. It can be concluded that the convection
coefficient is highest with the silver-chrome painted pipe and lowest with 85% magnesia
insulated pipe. Lagging efficiency is highest in 85% Magnesia insulated pipe and lowest
in painted pipe alone.

2. 1. Introduction
Factors affecting heat transfer and thermal performance through fibrous materials
occur in a combination of the following three mechanisms: conduction – transfer of the
energy of motion between adjacent molecules, convection – transfer of heat by bulk
transport and mixing of macroscopic elements of warmer portions with cooler portions of
gas or liquids, and radiation – no physical medium is needed for its propagation.
This heat loss figure is normally given in either kilowatts (kW) or British Thermal
Units (BTUs) and represents the energy required to keep a room at a given temperature
on the coldest days. It is essential to understand how heat loss can affect an underfloor
heating installation, as a system needs to provide adequate heat to be used as the
primary source of heating so that it increases comfort when used alongside other heating
systems.
The thermal conductivity will increase with temperature, as the component heat
transfer mechanisms increase, but the rate of increase and the final value at any
temperature will depend on the density and the quality of the material in the insulating
material.
The rate of heat loss from the surface may be expressed as:
𝑄
𝜃
= (hc + hr)A∆𝑇
The quantity
𝑄
𝜃
is calculated from the quantity of steam condensate, the latent heat
of vaporization, and the time of the run. However, some of the condensate flashes
because the condensate leaves the system at a pressure higher than atmospheric, and
the volume of condensate collected is smaller than the amount of steam condensed.
In this experiment, convection coefficient is determined at various temperatures
from different temperatures one of which are lagged pipes. Pipe lagging is a special type
of insulation fitted around water pipes. It keeps heat within the pipes - so it’s useful for
saving energy as well as preventing pipes from freezing and bursting. Lagging also
prevents condensation forming on cold pipes.

3. 2. Materials and Methods
2.1 Equipment and Materials
 Boiler
 Test pipes – bare, paint, silver chrome paint, and 85% magnesia insulation
 Thermocouple
 Beakers
 Graduated Cylinder
 Stopwatch
2.2 Methods
Three runs were made with steam at approximately 30 psig for each run:
1. After adjusting the system to the desired pressure, the drain cock was cracked
under the header to remove the water from the steam line and header.
2. The four plug – type valve was opened to blow out any condensate from the
pipes and then closed until only small amount of steam had escaped along with
the condensate.
3. When the system had reached the equilibrium, as determined by surface
temperature measurements, condensate was collected and measure from each
pipe over a time interval of 15 to 30 minutes, and during this period the following
data were recorded:
i. Barometric pressure
ii. Room temperature
iii. Stream pressure and temperature
iv. Surface temperature
Surface temperatures were taken at three or more equally spaced points along
each test pipes, and at least three sets of readings were taken during each run. This was
because as steam rising from the condensate, valves tend to heat the pipes and insulate
them. No temperature measurements were made within 20 inches of the exit ends of the
pipe.

4. 3. Results
Table 3.1 Tabulated Data of Heat Loss in Bare and Lagged Pipes
LENGTH OF PIPE
PIPE NO 1 2 3 4
COVERING PAINT BARE PIPE
SILVER –
CHROME
PAINT
85% MAGNESIA
INSULATION
OUTSIDE
DIAMETER, in.
1.34 1.34 1.34 2.48
EMMISIVITY 0.95 0.95 0.35 0.95
RUN NO. 1
BAROMETRIC
PRESSURE
1 atm
STEAM
PRESSURE
30 psig
STEAM
TEMPERATURE
100 ˚C
ROOM
TEMPERATURE
31 ˚C
TIME/RUN 15 minutes
PIPE NO. 1 2 3 4
S
U
R
F
A
C
E
T
E
M
P
E
R
A
T
U
R
E
TRIAL
560
mL
600
mL
525
mL
560
mL
590
mL
520
mL
345
mL
360
mL
330
mL
345
mL
360
mL
435
mL
1st
A 63 ˚C 67 ˚C 58 ˚C 54 ˚C
B 68 ˚C 66 ˚C 73 ˚C 53 ˚C
C 55 ˚C 60 ˚C 70 ˚C 51 ˚C
D 58 ˚C 64 ˚C 73 ˚C 56 ˚C
2nd
A 70 ˚C 60 ˚C 76 ˚C 52 ˚C
B ------ 92 ˚C ---- ----
C 68 ˚C 69 ˚C 90 ˚C 55 ˚C
D 90 ˚C 83 ˚C 106 ˚C 63 ˚C
3rd
A 83 ˚C 85 ˚C 96 ˚C 63 ˚C
B 72 ˚C 60 ˚C 97 ˚C 55 ˚C
C 75 ˚C 75 ˚C 91 ˚C 61 ˚C
D 85 ˚C 74 ˚C 94 ˚C 58 ˚C
AVERAGE Ts
71.55 ˚C or
160.79 ˚F
71.25 ˚C or
160.25 ˚F
84 ˚C or
183.2 ˚F
56.45˚C or
133.61 ˚F
Volume of Condensate
(mL), W
561.67 mL 556.67 mL 345 mL 381.67 mL

5. Table 3.2 Tabulated Results of Heat Loss in Bare and Lagged Pipes
PIPE NO. 1 2 3 4
COVERING PAINT BARE PIPE
SILVER –
CHROME PAINT
85% MAGNESIA
INSULATION
convection
coefficient, hc
2.12366 2.11972 2.27068 1.62058
radiation
coefficient, hr
0.01371 0.01361 0.00677 0.0093
Lagging Efficiency
(using QB), LE
0.93609 0 40.5727 65.4684
Lagging Efficiency
(using WB), LE
0.8982 0 38.0243 31.4369
𝑄
𝜃
220.01 217.97 306.46 360.671
4. Calculations
1 atm = 14. 7 psia
Ptot = 30 + 14.7 = 44.7 psia
From Steam Table @ 44.7 psia:
HL1= 242.92 Btu / lb
HL2 = 179.56 Btu / lb
HV2 = 1149. 76 Btu / lb
HL1 = xHL2 + (x-1)HV2
242.92 = 179.56x + (1-x)*( 1149. 76)
x = 0.935
 getting hc
For painted pipe:
hc = 0.42 (
∆𝑇
𝐷
)0.25
hc = 0.42 (
160.25−87.8
1.34/12
)0.25
hc = 2.12366 BTU/hr ft2 ˚F

6. For bare pipe:
hc = 0.42 (
∆𝑇
𝐷
)0.25
hc = 0.42 (
160.79−87.8
1.34/12
)0.25
hc = 2.11972 BTU/hr ft2 ˚F
For silver-chrome paint pipe:
hc = 0.42 (
∆𝑇
𝐷
)0.25
hc = 0.42 (
183.2−87.8
1.34/12
)0.25
hc = 2.27068 BTU/hr ft2 ˚F
For 85% Magnesia insulated pipe:
hc = 0.42 (
∆𝑇
𝐷
)0.25
hc = 0.42 (
133.61−87.8
2.48/12
)0.25
hc = 1.62058 BTU/hr ft2 ˚F
 getting hr
For Painted pipe:
hr =
0.173𝑝[(
𝑇𝑠
100
)
4
−(
𝑇𝑟
100
)
4
]
∆𝑇
hr =
0.173(0.95)[(
160.79
100
)
4
−(
87.8
100
)
4
]
(160.79−87.8)
hr = 0.01371 BTU/hr ft2 ˚F
For Bare pipe:
hr =
0.173𝑝[(
𝑇𝑠
100
)
4
−(
𝑇𝑟
100
)
4
]
∆𝑇
hr =
0.173(0.95)[(
160.25
100
)
4
−(
87.8
100
)
4
]
(160.25−87.8)
hr = 0.01361 BTU/hr ft2 ˚F

7. For Silver-chrome Painted pipe:
hr =
0.173𝑝[(
𝑇𝑠
100
)
4
−(
𝑇𝑟
100
)
4
]
∆𝑇
hr =
0.173(0.35)[(
183.2
100
)
4
−(
87.8
100
)
4
]
(183.2−87.8)
hr = 0.00677 BTU/hr ft2 ˚F
For 85% Magnesia Insulated pipe:
hr =
0.173𝑝[(
𝑇𝑠
100
)
4
−(
𝑇𝑟
100
)
4
]
∆𝑇
hr =
0.173(0.95)[(
133.61
100
)
4
−(
87.8
100
)
4
]
(133.61−87.8)
hr = 0.0093 BTU/hr ft2 ˚F
 getting
𝑄
𝜃
For Silver- chrome pipe:
𝑄
𝜃
= (hc + hr)A∆𝑇
𝑄
𝜃
= (2.270.68 + 0.00677)*(π(1.67)2
)(183.2- 87.8)
𝑄
𝜃
= 306.406 Btu / lb
 getting LE (using QB)
LE =
QB−QL
QB
x 100
For painted pipe:
LE =
217.97−QL
217.97
x 100
LE = 0.93609%
For silver-chrome painted pipe:
LE =
217.97−QL
217.97
x 100
LE = 40.5727%
For 85% Magnesia insulated pipe:
LE =
217.97−QL
217.97
x 100
LE = 65.4684%

8.  getting LE (using WB)
LE =
WB−WL
WB
x 100
For painted pipe:
LE =
556.67−WL
556.67
x 100
LE = 0.8982%
For silver-chrome painted pipe:
LE =
556.67−WL
556.67
x 100
LE = 38.0243%
For 85% Magnesia insulated pipe:
LE =
556.67−WL
556.67
x 100
LE = 31.4369%
5. Sketch

9. 6. Discussion
Several factors affect the heat loss in a system, these include the surface area of
the pipe, material in contact with the pipe and the type of material used. As observed from
the experiment, different pipes have different surface areas and temperature with different
materials used such as paint, silver-chrome paint and 85% insulation with Magnesia; thus,
yielding different lagging efficiency and different convection coefficient.
Piping insulation or lagging is essential for saving energy this is due to insulation
of your pipes stops most of the heat from leaking out as the water travels from the hot
water system to your water outlet; moreover, hot pipes are lagged for energy efficiency,
cold pipes are lagged to prevent the water freezing and bursting the pipe especially during
seasons where temperature is lowest. Thus, it is important to know the lagging efficiency
of pipes at a particular insulating material.
Evident differences in the lagging efficiencies were observed between the
computation using the heat loss and the steam condensate collected. This may be due
to the fact that the boiler used in the experiment isn’t constantly on. The thermocouple
used is defective at times, and mainly due to human errors.

10. 7. Conclusion
In general, the thermal conductivity increases with the rise of temperature, as the
component heat transfer mechanisms increase, but the rate of increase and the final
value at any temperature will depend on the density and the quality of the material (or in
this case, paint) in the insulating material.
The convection coefficient hc at various temperatures from different surfaces are
as follows: 2.11972 BTU/hr ft2 ˚F for bare pipe, 2.4255 BTU/hr ft2 ˚F for painted pipe,
2.2707 BTU/hr ft2 ˚F for silver-chrome paint pipe, and 1.62058 BTU/hr ft2 ˚F.
And their lagging efficiency with respect to the heat loss from the bare pipe are as
follows: 0.93609% for painted pipe, 0 % for bare pipe, 40.5727% for silver-chrome painted
pipe, and 65.4684 % for 85% Magnesia insulated pipe; and with respect to the volume of
condensate of bare pipe, their lagging efficiencies are: 0.8982% for painted pipe, 0% for
bare pipe, 38.0343% for silver-chrome painted pipe, and 32. 4369% for 85% Magnesia
insulated pipe.
8. Recommendation
In this experiment, it is best to use the highest quality of equipment and apparatus,
have proper execution of the experiment by the people assigned to it and setting the
experiment in the best atmosphere where there are no distractions and the like that may
alter results in order to achieve accurate data especially in getting the temperatures of
the different pipes at different time period since it is the basic data required in getting the
convection coefficient, radiation coefficient, heat loss and the lagging efficiency.

11. 9. References
[1] Geankoplis, C.J. (2009) Principles of Transport Processes and Separation
Processes. 1st edition. Pearson Education South Asia PTE. LTD.
10.Web References
[1] What is Heat Loss and Why Does It Matter | Warmup | Blog. (2017, December 13).
Retrieved January 29, 2018, from http://www.warmup.com/blog/what-is-heat-loss-
and-why-does-it-matter-2
[2] Heat Loss Calculation Principles (2016). Insulpro Insulation. Retrieved January 29,
2018, from https://insulpro.co.za/heat-loss-calculation-principles/