Mapúa Institute of Technology

School of Mechanical and Manufacturing Engineering

EXPERIMENT NO.1

HEATING SURFACE OF A BOILER

14 Martinez, James Ron D. Date Performed: August 26, 2022

ME144L-2 / C2 Date Submitted: August 26, 2022

2020100760

Engr. Teodulo A. Valle

INSTRUCTOR GRADE
 TABLE OF CONTENTS

Objectives 1

Theories and Principles 1

List of Apparatus 3

Procedure 5

Set-up of Apparatus 8

Final Data Sheet 9

Computation 10

Test Data Analysis 12

Question with Answers / Problem with Solutions 13

Conclusion 15

References 16

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Objectives:

• To be able to determine the heating surface area of the Mapua University Fire Tube Boiler.

• To compare Experimental Value of the heating surface area total to the True Value of the

heating surface area total.

• To be familiar with Fire Tube Boilers.

Theory and Principle:

Boilers can be classified into two types, namely, the two types are Water-tube boilers and

Fire-tube boilers. Each type has their own specifications that may suitably fit different applications.

Water-tube boilers have safer design in comparison to Fire-tube boilers, thus they typically outlast

Fire-tube boiler’s life span in terms of operation. On the other hand, Fire-tube boilers costs less

than Water-tube boilers to operate. Their differences are caused by how they are designed to

operate. Fire-tube boilers has hot gases from a fire blown through the first pass tube, into the

second pass tubes, followed by the third pass tubes, and lastly out to the exhaust. These tubes are

sealed in a container with water. On the contrary, the water in the Water-tube boilers is contained

in these tubes sealed in a container filled with hot gases. Both boilers end desired result is the

transfer of heat from hot gases to the water (Ohio Heating, 2016).

The heating surface, from the name itself is the surface being heated. Focusing on the

design of a Fire-tube boiler as the experiment will be referring to a Fire-tube boiler of Mapua

University, the heat will be released from the hot gas contained in a tube and absorbed into the

water. Therefore, the heating surface is the surface in which the heat transfer occurs will be the

surface that the water touches wherein convection occurs since this is the desired output of the

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boiler (Forbes Marshall, n.d.; Zhengzhou Boiler, n.d.). Considering this identification of the

heating surface, the equations for solving the heating surface area of the boiler is expressed below.

𝐴1 = 𝜋𝑑𝑚 𝐿1 𝑁1 (1)

𝐴2 = 𝜋(𝑂𝐷2 )𝐿2 𝑁2 (2)

𝐴3 = 𝜋(𝑂𝐷3 )𝐿3 𝑁3 (3)

𝜋2 2
𝐴𝐶𝑆 = [𝑑𝐶𝑆 – 𝑑𝑚,1 𝑁1 – 𝑂𝐷22 𝑁2 – 𝑂𝐷32 𝑁3 ] (4)
2

𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑉𝑎𝑙𝑢𝑒 = 𝐴1 + 𝐴2 + 𝐴3 + 𝐴𝑐𝑠 (5)

For the first pass, equation 1, the average diameter (dm) of the inside and outside diameter

of the first pass from the ends of the boiler is assumed to be the outside diameter of the first pass

inside the boiler where convection occurs. The assumption is due to the lack of access or means to

measure the outside diameter of the first pass inside the boiler. The variable L in the equations

refers to the length of the tubes to be translate as the length of the heating surface area. The variable

N refers to how many tubes there are corresponding for each pass. Since the tubes are cylindrical,

the equation 1, 2, and 3 or equations regarding the heating surface area of the passes (A1, A2, and

A3) are derived from the circumference multiplied by length and quantity. As for the heating

surface area of the crown sheet, equation 4 is derived from the cross-section area of the boiler

subtracted by the cross section of all the tubes of each pass, all multiplied by two to consider the

front and back crown sheet, wherein dcs is the cross-section diameter of the boiler. Lastly, equation

5 expresses that the sum of all the heat surface area of the passes and the crown sheet is the

experimental value of the heating surface of the boiler.

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List of Apparatus:

1. Inside caliper

Figure 1. Inside Caliper (from limit-tools.com)

2. Outside caliper

Figure 2. Outside Caliper (from generaltools.com)

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3. Digital caliper

Figure 3. Digital Caliper (from elecrow.com)

4. Steel tape

Figure 4. Steel Tape (from perfectmeasuringtape.com)

5. Aluminum rod

Figure 5. Steel Tape (from lowes.com)

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 6. Boiler

Figure 6. Steel Tape (from mechanicalbooster.com)

Procedures:

1. Open the front and back cover of the boiler.

2. Count the number of tubes for each pass.

Figure 7. Utilization of Aluminum Rod

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3. Insert a long aluminum or wooden rod through the tube for each pass and mark the front

and back end of the inserted long aluminum or wooden rod using chalk or any visible

marker.

4. Pull out the long aluminum or wooden rod and attain the length of the tube for each pass

by measuring the end-to-end markings on the rod using steel tape.

5. Measure the inside and outside diameter of the tube for each passes using a caliper.

SET-UP OF APPARATUS

Fig. 1 Measurement of the tube Fig. 2 Measurement of the cr

6. Measure the diameter of the crown sheet cover using a steel tape.

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OF APPARATUS

Fig. 1 Measurement of the tube Fig. 2 Measurement of the crown

7. Calculate the total heating surface area of the boiler.

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Set-up of Apparatus:

A. Boiler with Opened Covers and Exposed Passes

Figure 10. Boiler with Opened Covers and Exposed Passes

Figure 10 presents a captured picture of the Mapua University Fire Tube Boiler with

opened covers. This set up is the first procedure taken so that the tubes and other important

parts can be accessed for the proceeding steps to be taken which involves taking measurements

and count. The steel rod markings will be used as the reference for taking the length of the

tubes in which it was inserted to. This process will be done for each of the passes. Calipers will

be used to measure the inside and outside diameters of the tubes while a steel tape will be

utilized for measuring the diameter of the crown sheet’s diameter.

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Final Data Sheet:

Table 1. Final Data Sheet

Number Inside Outside Heating

1 st 1 56 cm 62 cm 273 cm 50601.6
cm2
2 nd 38 58 mm 64 mm 298 cm 2276825.3
cm2
3 rd 30 58 mm 64 mm 304 cm 1833684.8
cm2
Crown Sheet Cover 150 cm ---------- 25499.9
cm2
True Value = 503 ft² Experimental Value = 524 ft2

Per Cent Error = 0.0417 or 4.17%

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Computation:

1st Pass Heating Surface:

𝑂𝐷1 = 62 𝑐𝑚, 𝐼𝐷1 = 56 𝑐𝑚, 𝐿1 = 273 𝑐𝑚, 𝑁1 = 1

𝑂𝐷1 + 𝐼𝐷1 62 𝑐𝑚 + 56 𝑐𝑚
𝑑𝑚 = = = 59 𝑐𝑚
2 2

𝐴1 = 𝜋𝑑𝑚 𝐿1 𝑁1 = 𝜋 ∙ 59 𝑐𝑚 ∙ 273 𝑐𝑚 ∙ 1 = 𝟓𝟎𝟔𝟎𝟏. 𝟔 𝒄𝒎𝟐

2nd Pass Heating Surface:

𝑂𝐷2 = 64 𝑚𝑚, 𝐿2 = 298 𝑐𝑚, 𝑁2 = 38

1 𝑐𝑚
𝐴2 = 𝜋(𝑂𝐷2 )𝐿2 𝑁2 = 𝜋 ∙ (64 𝑚𝑚 × ( )) ∙ 298 𝑐𝑚 ∙ 38 = 𝟐𝟐𝟕𝟔𝟖𝟐. 𝟓 𝒄𝒎𝟐
10 𝑚𝑚

3rd Pass Heating Surface:

𝑂𝐷3 = 64 𝑚𝑚, 𝐿3 = 304 𝑐𝑚, 𝑁3 = 30

1 𝑐𝑚
𝐴3 = 𝜋(𝑂𝐷3 )𝐿3 𝑁3 = 𝜋 ∙ (64 𝑚𝑚 × ( )) ∙ 304 𝑐𝑚 ∙ 30 = 𝟏𝟖𝟑𝟑𝟔𝟖. 𝟓 𝒄𝒎𝟐
10 𝑚𝑚

Crown Sheet Cover Heating Surface:

𝜋 2 2
𝐴𝐶𝑆 = [𝑑𝐶𝑆 – 𝑑𝑚,1 𝑁1 – 𝑂𝐷22 𝑁2 – 𝑂𝐷32 𝑁3 ]
2

10
 2 2
𝜋 1 𝑐𝑚 1 𝑐𝑚
𝐴𝐶𝑆 = [(150 𝑐𝑚)2 – (59 𝑐𝑚)2 ∙ 1– (64 𝑚𝑚 × ( )) ∙ 38– (64 𝑚𝑚 × ( ))
2 10 𝑚𝑚 10 𝑚𝑚

∙ 30] = 𝟐𝟓𝟒𝟗𝟗. 𝟗 𝒄𝒎𝟐

Experimental Value in ft2:

𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑉𝑎𝑙𝑢𝑒 = 𝐴1 + 𝐴2 + 𝐴3 + 𝐴𝑐𝑠

𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑉𝑎𝑙𝑢𝑒 = 50601.6 𝑐𝑚2 + 227682.5 𝑐𝑚2 + 183368.5 𝑐𝑚2 + 25499.9 𝑐𝑚2

2
2
1 𝑓𝑡
= 487152.5 𝑐𝑚 ( ) = 𝟓𝟐𝟒 𝒇𝒕𝟐
30.48 𝑐𝑚

Percent Error:

𝑇𝑟𝑢𝑒 𝑣𝑎𝑙𝑢𝑒 = 503 𝑓𝑡 2

(𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒 − 𝑇𝑟𝑢𝑒 𝑣𝑎𝑙𝑢𝑒 ) 524 𝑓𝑡 2 − 503 𝑓𝑡 2

= 𝟎. 𝟎𝟒𝟏𝟕 𝒐𝒓 𝟒. 𝟏𝟕%

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Test Data Analysis:

Using equation 1, 2, and 3 in the computation, the heating surface area of the 1st, 2nd, 3rd is

calculated. Since only the front and back cover were opened, referring to the set-up of apparatus,

the assumption of having the mean diameter of the 1st pass from the end of the boiler as the outside

diameter inside the boiler is made. For the 1st, 2nd, and 3rd pass, the heating surface area are not

utilized the inside diameter of the tube as the heat from hot gas being transferred to the pipe is not

the desired output. Instead, the outside diameter (OD) of the tubes were utilized for calculating the

heating surface area where the heat is being transferred to the water. To avoid duplication of the

heating surface area of the tubes from the crown sheet, they are subtracted in the computation

under Crown Sheet Cover Heating Surface. The sum of these calculated heating surface areas is

theoretically the heating surface area of the entire boiler. To test the accuracy of the result, the

percent error of the true value to the calculated value was computed. The Percent Error is

calculated to be 4.17% which can be deemed to be negligible, thus proving the practice of the

theory to be true. The discrepancy may have come from the limitation of equipment used, such as

the centimeters in the steel tapes having an increment of 1 millimeter or 0.1 centimeter, as the

computation for lengths in centimeter was limited to one decimal place

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Questions with Answers / Problem with Solutions:

1. What is Flue Gas Temperature?

Flue Gas Temperature is a proximate indication of scale or deposit development in

which the boiler has to be examined of. An increase in flue gas temperatures over a period

of time typically signifies the accumulation of a deposit on the fireside or waterside of the

heat-exchange surfaces of the boiler.

2. What is more efficient between Water-tube boilers and Fire-tube boilers?

In comparison to fire tube boilers, which are the other type of boiler design, water

tube boilers are far more efficient. This is caused by a number of factors, including how

rapidly water converts into steam. The heat source surrounds the water as it moves through

the tube, not the other way around, making the water. Additionally, water-tube boilers use

less water since the water is in the tube of the passes thus making water turn to steam more

quickly.

Problem for 3 to 5: With feed water burning at 350 Kelvin and a pressure of 1.24 megapascal,

a boiler produces 8 kilograms of steam for every 1 kilogram of coal burned. Boiler efficiency

is 0.77, evaporation factor (FE) is 1.17, and the specific heat of steam at constant pressure is

2.3.

3. Calculate the temperature of steam generated and degree of superheat.

Using Steam Tables:

Properties at 1.24 MPa:

𝑘𝐽 𝑘𝐽
ℎ𝑓 = 805.28 , ℎ𝑔 − ℎ𝑓 𝑜𝑟 ℎ𝑓𝑔 = 1980.7
𝑘𝑔 𝑘𝑔

𝑇𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 = 189.48 ℃ 𝑜𝑟 462.63 𝐾

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 [{ℎ𝑓 + ℎ𝑓𝑔 + 𝐶𝑝𝑠 (𝑇𝑠𝑢𝑝𝑒𝑟ℎ𝑒𝑎𝑡𝑒𝑑 − 𝑇𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 )} − ℎ𝑓1
𝐹𝐸 =
2257

1.17

𝑘𝐽 𝑘𝐽
[{805.28 + 1980.7 + 2.3(𝑇𝑠𝑢𝑝𝑒𝑟ℎ𝑒𝑎𝑡𝑒𝑑 − 462.63 𝐾)} − 1 × 4.187 × (343.15 𝐾 − 273.15 𝐾)]
𝑘𝑔 𝑘𝑔
=
2257

𝑻𝒔𝒖𝒑𝒆𝒓𝒉𝒆𝒂𝒕𝒆𝒅 = 𝟓𝟐𝟔. 𝟖𝟗 𝑲

𝐷𝑒𝑔𝑟𝑒𝑒 𝑜𝑓 𝑠𝑢𝑝𝑒𝑟ℎ𝑒𝑎𝑡 = 𝑇𝑠𝑢𝑝𝑒𝑟ℎ𝑒𝑎𝑡𝑒𝑑 − 𝑇𝑠𝑎𝑡 = 526.89 𝐾 − 462.63 𝐾 = 𝟏𝟎𝟎. 𝟐𝟔 𝑲

4. Calculate the calorific value of coal in kilojoules per kilogram.

𝑚𝑠 (ℎ − ℎ𝑓1 )
𝑁𝑒𝑤 𝐵𝑜𝑖𝑙𝑒𝑟 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝑚𝑓 × 𝐶𝑉

0.77

𝑘𝐽 𝑘𝐽
8 𝑘𝑔 [{805.28 + 1980.7 + 2.3(526.89 𝐾 − 462.63 𝐾)} − 1 × 4.187 × (343.15 𝐾 − 273.15 𝐾)]
𝑘𝑔 𝑘𝑔
=
1 𝑘𝑔 × 𝐶𝑉

𝑪𝑽 = 𝟐𝟕𝟒𝟑𝟓 𝒌𝑱/𝒌𝒈

5. Calculate the equivalent evaporation (EE) in kilograms of steam per kilogram of coal.

𝐸𝐸
𝐹𝐸 =
𝑚𝑠

𝐸𝐸
1.17 =
8 𝑘𝑔 𝑜𝑓 𝑠𝑡𝑒𝑎𝑚
1 𝑘𝑔 𝑜𝑓 𝑐𝑜𝑎𝑙

𝒌𝒈 𝒐𝒇 𝒔𝒕𝒆𝒂𝒎
𝑬𝑬 = 𝟗. 𝟑𝟔
𝒌𝒈 𝒐𝒇 𝒄𝒐𝒂𝒍

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Conclusion:

By understanding the design, operation, and function of the Fire-tube boiler, the heating

surface was elaborately defined and identified for the boiler, specifically, the Fire-tube boiler of

Mapua University. Moreover, using the principle of heat transfer and the intentional design of the

Fire-tube boiler, which was also observed in the set-up, the derivation of equations was presented

in the experiment. From the computation, the experimental and true value of the heating surface

area of the boiler were also shown to be negligible. Overall, the small percent error validated that

heating surface area of the Mapua University Fire Tube Boiler was determined. The procedures

taken and understanding of the principles and equations ensured that the experiment was able to

be familiarized with the Fire Tube Boiler.

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References:

Forbes Marshall. (n.d.). Introduction to Boilers. Retrieved August 26, 2022, from

https://www.forbesmarshall.com/Knowledge/SteamPedia/Boilers/What-is-a-Boiler-

Introduction-to-

Boilers#:%7E:text=The%20heating%20surface%20is%20any,is%20expressed%20in%20

square%20meters.

Ohio Heating. (2016, May 1). What is a Fire Tube Boiler? Ohheating. Retrieved August 26,

2022, from https://www.ohheating.com/tips-blog/what-is-a-fire-tube-boiler

Zhengzhou Boiler. (n.d.). formula of boiler heating surface. Zbgboilerfactory. Retrieved August

26, 2022, from https://www.zbgboilerfactory.com/Sep-23/18760.html

Figure 1 source: https://limit-tools.com/product/inside-caliper-200mm-2/

Figure 2 source: https://generaltools.com/10-in-outside-caliper

Figure 3 source: https://www.elecrow.com/8-digital-vernier-caliper-p-1431.html

Figure 4 source: https://perfectmeasuringtape.com/shop/customizable-series-100-25ft-75m-

professional-wide-read-steel-tape-measure/

Figure 5 source: https://www.lowes.com/pl/Aluminum--Rods-Metal-rods-shapes-sheets-

Hardware/1408627087?refinement=4294965691

Figure 6 source: https://www.mechanicalbooster.com/2016/07/what-is-a-boiler-different-types-

of-boiler.html

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