lab report 4 major minor losses

An Analysis of Major and Minor Losses in Pipes and Fittings Roger Smith Team 3

friction and minor loss is caused Abstract. In pipes, major loss in straight sections is caused by friction by fittings, both resulting in a drop in pressure. Major and minor losses can substantially affect the effectiveness and efficiency of a given fluid transport system. Experiments were performed to measure the effect of diameter on the Darcy friction factor (f) in two five-foot copper pipe sections using a Technovate fluid circuit system and the effect of fitting type on the minor loss coefficient ( !" ) for a long elbow, sudden enlargement, sudden contraction, medium elbow, short elbow, and right-angle fitting using a Edibon Energy Losses in Bends Module FME05. Friction factors obtained ranged from 0.0023 to 0.0192 for the smaller (9.53-mm-diameter) pipe section and from 0.0005 to 0.0260 for the larger (12.7-mm-diameter) pipe section, with values that mostclosely reflected theoretical values occurring with higher pressure drop readings and velocity squared values. The highest minor loss coefficients were also observed at higher velocity squared values and pressure drop readings, with average values ranging from a low of 0.08 for the sudden enlargement fitting to a high of 0.46 for the right-angle fitting. Keywords: Major loss, minor loss, Darcy friction friction factor, minor loss coefficient, Colebrook equation Introduction

A pressure drop occurs when a flow experiences friction in a straight pipe section, and this loss is referred to as major loss. Pressure loss that occurs when a fluid encounters fittings, such as values, bends, inlets, outlets, expansions, or contractions is (typically, although not always) less substantial when compared to frictional effects and, as a result, referred to as minor loss. The properties and effects of major and minor losses apply to numerous man-made and natural phenomena, ranging from large-scale industrial systems to microscopic biological systems systems and compose a significant consideration when designing fluid transport systems. The design of nuclear reactors, for example, involves a very careful development of such systems and the losses involved, as piping geometry and loss-of-coolant play a very important role in the overall effectiveness and safety of the system (Bowden and Yang, 2016). This lab seeks to develop a deeper understanding of major and minor losses and the physical properties related to each. Objectives

The objectives of these experiments were to (1) measure the effect of pipe diameter on friction factor (major loss) and (2) measure the effect of fittings (minor loss) in pipes with flowing fluid.

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Materials and Methods

Equipment The equipment used for this lab was a Technovate fluid circuit system for the major loss portion and an Edibon Energy Losses in Bends Module FME05, pictured below, for the minor loss portion.

Edibon Energy Losses in Bends Module FME05

Procedure Major Loss Two five-foot pipe sections with diameters of 9.53 mm and 12.7 mm were observed. The flow rate of the system was controlled with a valve, va lve, and six readings for pressure drop across the orifice and pipe section were recorded. The data collected began in full flow and became more restricted as the valve was tightened following each incremental reading taken. Pressure drop across the orifice was used to determine the volumetric flow rate (# ), while pressure drop across the pipe ($%) was used to calculate the friction factor ( &). The pressure drop -3 across the orifice was multiplied by water density of 998.3 kg m and gravity to arrive at pressure loss value in pascal units. The pressure drop across the pipe was kept in terms of head loss (m). The data obtained was entered into Microsoft Excel for analysis and evaluated with theoretical equations listed below. The properties of water at room temperature of 20 C were used for all calculations. °

Volumetric flow rate was calculated according to the following equation:





! ' density of water

89 :;

*+ ' discharge coefficient of orifice -
:; 89

" ' orifice inner diameter to outer diameter ratio

: :

The discharge coefficient =*+ ), inner orifice diameter and outer orifice diameter were provided with values of 0.656, 0.015875 m, and 0.026035 m, respectively. The diameter ratio (" (" )) was calculated from the inner and outer ou ter orifice diameter values. Once volumetric flow rate was known, the Darcy friction factor was obtained by rearranging the following equation:

$% ' &

" ? @ > ,9

(2)

where: $% ' head loss across pipe section (m) & ' friction factor : A ' gravity @ B L ' pipe length (m) (m ) : C ' velocity B

D ' pipe diameter (m) Velocity =CE was calculated by dividing the volumetric flow rate by the cross-sectional area of each pipe, using inner diameter values of 6.29 mm and 8.38 mm, per typical ratio diameter values for copper pipes derived from the Engineering Toolbox online resource. Known values for the equation were entered for each velocity squared (C , ) value, and theoretical & values were calculated using the Colebrook equation, using a pipe roughness (!) value of 0.0015 mm (Cengel and Cimbala, 2011). Minor Loss The Edibon module contained the follow six fittings with corresponding tap numbers: long elbow (tap 1 and 2), sudden enlargement from 20 to 40 mm (tap 3 and 4), sudden contraction from 40 to 20 mm (tap 5 and 6), medium elbow (tap 7 and 8), short elbow (tap 9 and 10), and right-angle miter (tap 11 and 12). All fittings were attached to a shared 20-mm base line. A control valve was used to control flow rate, and six flow rate and pressure readings were taken until the right-angle pressure drop nearly leveled-out. The reading intervals were spaced into 30second intervals. Because the flow rate volume vo lume (in liters) was measured for each interval, the





$ & ' !"

?@

(3)

,9

where: $ & ' head loss (m) !" ' minor loss coefficient

C ' velocity A ' gravity

:

B : B@

The cross-sectional area used to determine velocity from vo lumetric flow rate reading was calculated using a 20-mm diameter, because that was a pipe diameter that was shared and could be applied across all fittings for the purposes of calculation. Head loss ($ &) was then plotted across each fitting versus the square of velocity, and theoretical resistance coefficient values provided by Fox et al were compared to the values calculated from the data obtained. The minor loss coefficient data was further analyzed using relative relative error in order to obtain insight into the magnitude of the difference between the experimental and theoretical values. The results and findings of the experiment and subsequent analysis are outlined in the following section. Results and Discussion

For the 9.53-mm-diameter pipe section, experimental and theoretical & values displayed a relatively wide discrepancy in value at lower velocity, but trended toward one another as squared 2 -2 2 -2 velocity increased. Velocity squared ranged from 8.58 m s at full flow to 0.365 m s at the low flow and, correspondingly, the lowest level of pressure drop (62.2 Pa). The friction factor tended to increase as velocity squared increased for the experimental data, while the friction factor decreased for the theoretical data, although the highest experimental friction factor (0.0192) occurred in the middle of o f the data set (fig. 1).





*)*.*

CDE'&#?'647<

FG'5&'4#37<

*)*-+ *)*-* !

& 5 4 3 7 " 6 5 # 4 3 # & "

*)*,+ *)*,* *)*(+ *)*(* *)**+ *)*** * )* *

( )* *

,)**

-)**

. )* *

+ )* *

/)* *

0)**

1)**

2 )* *

(*)**

89%7&' 5: ;'<53#4= >? ,@A,B

"#$%&' () "#$%&'(%)*+, +)- ./%0&%*'1+, &%23,*2 40& 4&'1*'0) 4+1*0& 5%&232 263+&% 04 5%,01'*7 40& 89:;<((<-'+(%*%& 4'5%<400* $'$% 2%1*'0)9

In regard to friction observed and pressure loss, experimental and theoretical values suggest friction values may be more accurately reflected when a higher level of pressure loss (and a higher corresponding velocity squared value) is observed in the pipe. For the 12.7-mm-diameter pipe section, experimental & values, as with the smaller diameter pipe section, displayed a larger discrepancy at lower squared velocity values but trended toward equaling out as each increased, per figure 2. A higher velocity squared value also corresponded with a higher pressure drop reading, again ag ain suggesting higher pressure loss readings may result in more accurate friction factor values. *)*-+ *)**)*,+ !

& 5 4 *)*, 3 7 " 6*)*(+ 5 # 4 3 # & "

CDE'&#?'647<

*)*(

FG'5&'4#37<

*)**+ * * )* *

()**

, )* *

- )* *

.)**

+ )* *

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0 )* *

89%7&' 5: ;'<53#4= >? ,@A,B

='>3&% ?9 "#$%&'(%)*+, +)- ./%0&%*'1+, &%23,*2 40& 4&'1*'0) 4+1*0& 5%&232 263+&% 04 5%,01'*7 40& @?9A<((<-'+(%*%& 4'5%<400* $'$% 2%1*'0)9





trendline (fig. 3). The right-angle fitting displayed highest resistance coefficient (0.46), while the sudden enlargement fitting displayed the lowest (0.08). *)*/*

*)*+*

= Q *)*,-0D = Q *)*(/0D

*)*.* B ? > A A 5 H L 7 ' R

= Q *)*(.,D *)*-* = Q *)**1D

H56$ C
*)*,* = Q *)**++D *)*(* = Q *)**.-D

O#$G4 P6$<' N'L#%? C
*)*** * )**

*)+*

( )* *

()+*

, )* *

,)+*

89%7&' 5: ;'<53#4= >? ,@A,B

='>3&% ;9 B%+- ,022 5%&232 263+&% 04 5%,01'*7 40& 2/0&*C (%-'3( +)- ,0)> %,D0EC %),+&>%(%)*C 10)*&+1*'0)C +)- &'>/*<+)>,% 4'**')>29

A comparison of experimental and theoretical loss coe fficient values are outlined in table 1. All values obtained reflect a high level leve l of relative error, with values ranging from a high of 86.4% for the sudden enlargement fitting to a low of 17.7% for the sudden contraction fitting.

.+D,% @9 F')0& ,022 ') $'$% 4'**')>2 < %#$%&'(%)*+, +)- */%0&%*'1+, ,022 10%44'1'%)* 5+,3%2 +)- 10&&%2$0)-')> &%,+*'5% %&&0&9 '()*+",*$#-. /011 20*33"4"*$# 567

89*0+*#"4-. /011 20*33"4"*$# 567

:*.-#";* '++0+ 5<7

H56$ C
*)(/

*),+

-/)*K

8%LL'6 C6<7&$'?'64

*)*1

*)+2

1/).K

8%LL'6 M564&734#56

*)--

*).*

(0)0K

N'L#%? C
*)((

*)+*

01)*K

8G5&4 C
*),1

*)0.

/()/K

O#$G4 P6$<' N#4'&

*)./

()(*

+0)1K

!"##"

%$In order to further analyze the minor loss coefficient data, the conditions under which the experimental data most-closely resembled theoretical data were considered. The experimental loss coefficient values for each fitting and corresponding flow velocities were compared to the theoretical values, and the value that most-closely reflected the theoretical value was marked. The results are displayed in table 2.







H56$ C
*),+

*),+

()**K

*).0/

8%LL'6 C6<7&$'?'64

*)(.

*)+2

0+)2K

*)(-1

8%LL'6 M564&734#56

*).(

*).*

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*).0/

N'L#%? C
*)(.

*)+*

0()+K

*)(-1

8G5&4 C
*).-

*)0.

.,)-K

*)(-1

O#$G4 P6$<' N#4'&

*)+.

()(*

+()-K

*).0/

2

-2

2

-2

While square of velocity values ranged from a high of 2.21 m s to a low of 0.138 m s , experimental loss coefficient values most closely resembled theoretical values for the long elbow, sudden contraction, and right-angle values when the square of velocity was at the mid2 -2 range level of 0.476 m s . The experimental loss coefficient values most closely reflected theoretical values for the sudden enlargement, medium elbow, and short elbow when the square 2 -2 of velocity and head loss reached their lowest levels of 0.138 m s and 0.001, 0.001, and 0.003, respectively. Conclusions

The major loss effect of pipe diameter on friction factor for two five-foot straight copper pipe sections and the minor loss effect of a long elbow, sudden enlargement, sudden contraction, medium elbow, short elbow, and right-angle fitting for flowing fluid was observed. Major and minor loss values most-closely reflected theoretical values when higher pressure drop readings and velocity squared values were observed. Friction factors for the 9.53-mm-diameter and 12.7-mm-diameter copper pipe sections obtained ranged from 0.0023 to 0.0192 and from 0.0005 to 0.0260, respectively. Average values for minor loss coefficient values ranged from the lowest value of 0.08 for the sudden enlargement fitting to the highest value 0.46 for the rightangle fitting and progressed with a mostly-linear trendline as pressure loss and velocity squared increased.

lab report 4 major minor losses

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