Experiment 1 Friction Losses in Pipes and Fittings PDF

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Republic of the Philippines BATANGAS STATE UNIVERSITY BatStateU Alangilan Alangilan, Batangas City College of Engineering, Architecture and Fine Arts batstate-u.edu/, Tel. No. (043) 425-0139 loc. 118/CHEMICAL AND FOOD ENGINEERING DEPARTMENTExperiment No. 1 ENERGY LOSS IN PIPESA Laboratory Report in ...

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Republic of the Philippines BATANGAS STATE UNIVERSITY BatStateU Alangilan Alangilan, Batangas City College of Engineering, Architecture and Fine Arts https://batstate-u.edu.ph/, Tel. No. (043) 425-0139 loc. 118/2121 CHEMICAL AND FOOD ENGINEERING DEPARTMENT

Experiment No. 1 ENERGY LOSS IN PIPES

A Laboratory Report in ChE 411 – Chemical Engineering Laboratory 1

Dimaculangan, Zyrene A. ChE – 3103

Engr. Jackie Meileen Yurong Course Instructor

September 2021

INTRODUCTION The fundamental laws of fluid flow govern pipe technology. When a fluid runs through a pipe, some of its energy is used in keeping the flow going. Friction loses energy as a fluid passes through a pipe. The amount of energy lost is affected by a variety of factors, including the fluid's speed and viscosity. The roughness of the pipe walls may also be an issue if the flow is turbulent. Friction losses cause pressure to drop throughout the length of the pipe, increasing the amount of power needed to keep the flow going. These losses can build up in systems with long piping sections, such as heat exchangers, oil pipelines, and fire suppression systems. The energy in pipe is transformed into thermal energy as a result of internal friction and turbulence. This conversion results in the expression of the energy loss in terms of fluid height, which is known as the head loss and is generally classified into two categories. The major losses are caused by frictional energy loss caused by the viscous effects of the fluid and the roughness of the pipe wall. Because the pressure must work against frictional resistance, major losses result in a reduction in pressure along the pipe. Minor losses, on the other hand, are energy losses caused by changes in the magnitude or direction of the flowing fluid's velocity and occur through fittings such as bends and couplings. The total energy loss in a pipe system is the sum of the major and minor energy losses. Although more complex to calculate and use than other friction loss formulas, the DarcyWeisbach equation is widely recognized as the most accurate pipe friction loss equation. It is a fluid mechanics empirical equation named after Henry Darcy and Julius Weisbach. The DarcyWeisbach equation relates the loss of pressure or head loss due to friction over a given length of pipe to the average velocity of an incompressible fluid's flow. The friction factor represents the pressure loss of a fluid in a pipe caused by interactions between the fluid and the pipe. The establishment of the friction factors, remained unsolved and required more study to create a solution. However, the Moody diagram/chart provides a technique for calculating an accurate friction factor and this encouraged to use the Darcy-Weisbach equation, which quickly became the method of choice for engineers. This diagram/chart is a graph that relates the friction factor, Reynolds number, and roughness parameter of pipes.

PRACTICAL APPLICATION Many industries and communities rely on gas and water distribution systems, sewage and drainage systems, cable protection, communication networks, and industrial infrastructure. Thousands of kilometers of existing pipes consisting of metallic, concrete, polymeric, and composite materials perform critical functions with various degrees of efficiency, but with a high degree of safety in general. Numerous existing pipe networks, on the other hand, are either locally or globally outdated, or they are prone to damage and failure. Certain pipe systems may have reached the end of their useful life and are at danger of failing, or they may need to be modified or replaced. It is essential in engineering applications to improve pipe productivity, such as maximizing flow rate capacity and minimizing head loss per unit length. Energy losses in pipes, which are used to transport fluids, are mostly caused by friction. These losses are often converted into head reductions in the flow direction. In industries, the aim is to maximize flow rate capacity and efficiency, therefore reducing head loss per unit length is essential. One way to meet this objective is to increase the system's pipe diameter. For a given flow rate, the Darcy-Weisbach equation states that head loss decreases with the inverse fifth power of the pipe diameter. When the diameter of a pipe is doubled, the head loss decreases by a factor of 32, or about 97 percent. In comparison, the quantity of material required per unit length of pipe, as well as the installation cost, nearly doubles. This means that in order to overcome frictional resistance in a pipe providing a given flow rate, energy consumption may be greatly reduced at a low capital cost. The majority of energy loss in pipes used to carry fluids such as water, petroleum, and natural gas is due to friction and the numerous singularities encountered. Typically, these losses are compensated for simply lowering the head in the direction of the flow. Understanding the data obtained by such transformations allows for the calculation of the needed power for transporting the fluid between two places. It establishes the mathematical basis for the design and analysis of transportation and distribution networks.

Moreover, engineers might also reduce the length and quantity of elbows, valves, fittings, and other obstructions in the system's piping. When designing an efficient pipe system, proper fitting may help decrease head loss and maximize flow rate. Through this experiment, the student will get an understanding of important considerations in the design of an efficient pipe system.

OBJECTIVES Objectives for this experiment include, but are not limited to, the following:  Determine and analyze the head loss produced by friction in a pipe  Utilize Darcy-Weisbach equation to get the friction coefficient  Understand the significance of pipe productivity, and the variety of conditions that affect pipe productivity and efficiency  Compare the experimental friction factor to an empirical equation, and the Moody diagram

METHOD The head loss in a straight pipe is determined with a manometer by measuring the difference between two fixed points at different places in the pipe. The friction factor can be computed by combining the calculated head loss with other raw data sources. In the following step, the result will be compared to other theoretical numbers such as the Blasius friction factor.

EQUIPMENT It is necessary to have the following equipment to carry out the energy loss in pipes experiment. The apparatuses used in the virtual simulator were: 

Pipeline



Pipe (40 mm diameter)



Differential manometer



Collecting tank



Stopwatch



Scale

EQUIPMENT DESCIPTION The pipe friction apparatus consists of a test pipe which is 3 meters long and has an inside diameter of 4 cm. A manometer is also used to measure the head losses by measuring the pressure differentials, also, the manometer is also used to remove the air inside the pipe. A main inlet valve and a collecting tank with an exit valve and scale are connected to the ends of the pipe. A stop watch is used to measure the time required for the water to rise by 10 cm through as scale.

THEORY The flow of fluid through a pipe is resisted by viscous shear stresses within the fluid and turbulence that occurs along the internal pipe wall when a gas or a liquid flows through it. Because energy is necessary to counteract the viscous or frictional forces produced by the pipe walls on the flowing fluid, there will be a loss of pressure in the fluid. In addition to the energy lost due mainly to frictional forces, energy is lost when fluid passes through fittings such as valves, elbows, contractions, and expansions. This pressure loss is mostly caused by local flow separation when it passes through such fittings. Head loss is the term used to describe the pressure loss in pipe flows. Frictional losses are mostly generated in straight pipes; minor losses are caused by friction loss induced in fittings like as bends, couplings, valves, or transitions in hose or pipe. Frictional losses are referred to as major losses (hf), whereas losses caused by fittings, etc. are referred to as minor losses (hm). They add up to the total head losses (h) for pipe flows.

Loss in a pipe flow is considered while calculating the rate of flow in pipes connecting two reservoirs at different levels or calculating the additional head necessary to double the rate of flow along an existing pipeline. These pipe losses are affected by a variety of factors, including the fluid's viscosity, the size of the internal pipe diameter, the internal roughness of the inner surface of the pipe, the change in elevation between the pipe's ends, the pipe's material, and the length of the pipe along which the fluid travels. Pipes with smooth surfaces do not account for more friction loss, but pipes with less smooth walls, such as concrete, cast iron, and steel fluid, require a huge amount of energy to overcome the friction produced in a pipe by the viscosity of the liquid. The rougher the inner wall of the pipe, the greater the pressure loss due to friction.

The friction loss in a uniform, straight sections of pipe, known as "major loss", is caused by the effects of viscosity, the movement of fluid molecules against each other or against the wall of the pipe that is possibly rough. Here, it is greatly affected by whether the flow is laminar or turbulent. 

Laminar Flow: It occurs when the fluid flows in parallel layers without adjacent mixing between the layers. In this type of flow there are neither eddies nor cross currents, with fast flow over the center part of the pipe and no movement near the pipe surface. The roughness of the pipe surface influences neither the fluid flow nor the friction loss. For laminar flow Reynolds number (Re) < 2100.



Turbulent Flow: It occurs when the liquid is moving fast with mixing between layers. The speed of the fluid at a point continuously undergoes changes in both magnitude and direction. For turbulent flow Reynolds's number 2100 < Re < 4000.



Transitional flow: is a mixture of laminar and turbulent flow, with turbulence flow in the center of the pipe and laminar flow near the edges of the pipe. Each of these flows behaves in different manners in terms of their frictional energy loss while flowing and have different equations that predict their behavior. For transitional flow Reynolds's number Re > 4000. The Darcy Equation is a theoretical equation that predicts the frictional energy loss in a

pipe based on the velocity of the fluid and the resistance due to friction. It is used almost exclusively to calculate head loss due to friction in turbulent flow. 𝒉𝒇 = Where: hf = friction head loss f = Darcy resistance factor L = length of the pipe D = pipe diameter v = mean velocity g = acceleration due to gravity

𝒇𝑳𝒗𝟐 𝟐𝑫𝒈

Laminar flow is the type of fluid flow which occurs in parallel layers without mixing between layers. The Reynolds number (Re) is less than 2100. In this type of low, the friction factor f is a function of the Reynolds number and is independent of the relative roughness of the pipe. Using the Hagen-Poiseuille equation, the friction factor can be calculated: 𝒇 = 𝟔𝟒/𝑹𝒆 On the other hand, turbulent flow is defined as a flow in which liquid is moving fast and mixing between layers. The Reynolds number is greater than 4000. Unlike laminar flow, the friction factor in turbulent flow is dependent on both the Reynolds number and relative roughness of the pipe. The relative roughness is expressed as k/D, where k is the roughness parameter and D is the inside diameter of the pipe. It can be calculated using the Blasius equation: 𝒇 = 𝟎. 𝟑𝟏𝟔𝑹𝒆−𝟎.𝟐𝟓 Furthermore, friction factor can be determined using a Moody diagram. It is a diagram which relates the friction factor to the relative roughness (k/D) and the Reynolds number. Blasius equation is a well-known curve fit to the Moody diagram.

EXPERIMENTAL PROCEDURE The purpose of this experiment is to determine the head loss and friction factor in a pipe. Five (5) trials will be conducted in order to achieve trustworthy results from the experiment.

An approximately 3-meter-long pipe with a 4-centimeter diameter was connected to a collecting tank and the primary input valve for the first-time attempt. The primary input valve was opened as soon as the pipe was opened, allowing water to flow through the pipe and into the tank.

Once the water began to flow, the knot on the manometer was shifted from its isolated position to an air-vent position, allowing air to escape from the inside of the pipe via the hole in the manometer. In order to read the manometer again, it was pushed back into the read position when the steady flow reached the inner wall of the pipe. The collecting valve's exit valve was opened, and water began to pour out in a steady stream. A reading of the manometer was taken and recorded.

The head loss was calculated based on the data from the left and right limbs. Following the closure of the collecting tank's exit valve, a scale and timer were used to measure the amount of time it took for the tank to rise by 10 centimeters. On the basis of the data, the discharge, velocity, and analytical friction factors were estimated and reported. After all, five (5) trials had been performed, the average analytical friction factor and other data were calculated, and the results were presented. These experimental values will be compared to the theoretical values in order to determine which is more accurate.

RESULTS AND CALCULATIONS This sectiomn comprises the raw data as well as the results of calculations produced from the experiment, which consisted of five (5) separate experiments in total. Table 1. Known Variables in the Experiment Provided in Simulator Virtual Lab Area of the collecting tank (A)

3500 cm2

Height of the tank (h)

10 cm

Diameter of the pipe (D)

40 mm or 4 cm

Length of the pipe (l)

3m or 300 cm

Assuming the experiment was done in a constant room temperature (25 deg C) conditions and the fluid used was water, the known data are: Table 2. Known Data of Density and Viscosity Density (ρ)

1 g/cm3

Viscosity (μ)

0.00890g/cm-s

RESULTS OF THE EXPERIMENT This sub-section encompasses the raw data obtained from the experiment, which are the left and right limb reading from the manometer and the time required for the water to reach a height of 10 cm in the tank. Table 3. Raw Data for the Five Trials Trial No.

Left Limb Reading (cm)

Right Limb Reading (cm)

Time (s)

1

30.5

38

33.5

2

30

38.5

30

3

28

40.5

16

4

31.5

37

42

5

28.5

40

19

The results in the table above reveal a small difference with one another. The manometer limb readings vary with very modest changes; nonetheless, for the time, certain trials reveal large discrepancies from the others.

Calculations of Experimental Values The following equations were used to obtain the experimental values of the experiment: 

Head Loss = 12.6 (| Left Limb Reading – Right Limb Reading |)



Qact =



Velocity =



Analytical Friction Factor =



𝐴𝑥ℎ 𝑡 𝑄𝑎𝑐𝑡 𝜋 𝑥 𝑑2 4

Reynolds Number =

2𝑔𝑑 𝑣2

x

𝐻 𝑙

𝜌𝑣𝐷 𝜇

Trial 1 Head Loss = 12.6 (|30.5-38|) Head Loss = 94.5 cm Qact =

(3500𝑐𝑚2 )(10𝑐𝑚) 33.5 𝑠𝑒𝑐

Qact = 1044.776119 Velocity =

𝑐𝑚3 𝑠

𝑐𝑚3 𝑠 𝜋 𝑥 (4 𝑐𝑚)2

1044.776119 4

Velocity = 83.14064188

𝑐𝑚

𝑠𝑒𝑐

𝑐𝑚

2(981 2 ) (4 𝑐𝑚)

𝑠 Analytical Friction Factor = (83.14064188 𝑐𝑚 2 x ) 𝑠𝑒𝑐

94.5 𝑐𝑚 300 𝑐𝑚

Analytical Friction Factor = 0.3576372954 Reynolds Number =

(1

𝑐𝑚 𝑔 ) (83.14064188 𝑠𝑒𝑐) 𝑐𝑚3 𝑔 0.00890 𝑐𝑚−𝑠

Reynolds Number = 37366.58062 Trial 2 Head Loss = 12.6 (|30-38.5|) Head Loss = 107.1 cm Qact =

(3500𝑐𝑚2 )(10𝑐𝑚) 30 𝑠𝑒𝑐

Qact = 1166.666667

𝑐𝑚3 𝑠

(4𝑐𝑚)

Velocity =

𝑐𝑚3 𝑠 𝜋 𝑥 (4 𝑐𝑚)2

1166.666667 4

Velocity = 92.8403835

𝑐𝑚

𝑠𝑒𝑐

𝑐𝑚

Analytical Friction Factor =

2(981 2 ) (4 𝑐𝑚) 𝑠 𝑐𝑚 (92.8403835 𝑠𝑒𝑐)2

x

107.1 𝑐𝑚 300 𝑐𝑚

Analytical Friction Factor = 0.3268734083 Reynolds Number =

(1

𝑐𝑚 𝑔 ) (92.8403835 𝑠𝑒𝑐) 𝑐𝑚3 𝑔 0.00890 𝑐𝑚−𝑠

(4𝑐𝑚)

Reynolds Number = 41726.01506 Trial 3 Head Loss = 12.6 (|28-40.5|) Head Loss = 157.5 cm Qact =

(3500𝑐𝑚2 )(10𝑐𝑚) 16 𝑠𝑒𝑐

Qact = 2187.5 Velocity =

𝑐𝑚3 𝑠

𝑐𝑚3 𝑠 𝜋 𝑥 (4 𝑐𝑚) 2 4

2187.5

𝑐𝑚

Velocity = 174.075719 𝑠𝑒𝑐

𝑐𝑚

Analytical Friction Factor =

2(981 2 ) (4 𝑐𝑚) 𝑠 𝑐𝑚

(174.075719 𝑠𝑒𝑐)2

x

157.5 𝑐𝑚 300 𝑐𝑚

Analytical Friction Factor = 0.1359696258 Reynolds Number =

(1

𝑔 𝑐𝑚 ) (174.075719 𝑠𝑒𝑐) 𝑐𝑚3 𝑔 0.00890 𝑐𝑚−𝑠

Reynolds Number = 78236.2782 Trial 4 Head Loss = 12.6 (|31.5-37|) Head Loss = 69.3 cm Qact =

(3500𝑐𝑚2 )(10𝑐𝑚) 42 𝑠𝑒𝑐

Qact = 833.3333333

𝑐𝑚3 𝑠

(4𝑐𝑚)

Velocity =

𝑐𝑚3 𝑠 𝜋 𝑥 (4 𝑐𝑚)2

833.3333333 4

Velocity = 66.31455962

𝑐𝑚

𝑠𝑒𝑐

𝑐𝑚

Analytical Friction Factor =

2(981 2 ) (4 𝑐𝑚) 𝑠 𝑐𝑚 (66.31455962 𝑠𝑒𝑐)2

x

69.3 𝑐𝑚 300 𝑐𝑚

Analytical Friction Factor = 0.4122429093 Reynolds Number =

(1

𝑐𝑚 𝑔 ) (66.31455962 𝑠𝑒𝑐) 𝑐𝑚3 𝑔 0.00890 𝑐𝑚−𝑠

(4𝑐𝑚)

Reynolds Number = 29804.29646 Trial 5 Head Loss = 12.6 (|28.5-40|) Head Loss = 144.9 cm Qact =

(3500𝑐𝑚2 )(10𝑐𝑚) 19 𝑠𝑒𝑐

Qact = 1842.105263 Velocity =

𝑐𝑚3 𝑠

𝑐𝑚3 𝑠 𝜋 𝑥 (4 𝑐𝑚)2

1842.105263 4

𝑐𝑚

Velocity = 146.5900792 𝑠𝑒𝑐

𝑐𝑚

Analytical Friction Factor =

2(981 2 ) (4 𝑐𝑚) 𝑠 𝑐𝑚

(146.5900792 𝑠𝑒𝑐)2

x

144.9 𝑐𝑚 300 𝑐𝑚

Analytical Friction Factor = 0.1763993442 Reynolds Number =

(1

𝑔 𝑐𝑚 ) (146.5900792 𝑠𝑒𝑐) 𝑐𝑚3 𝑔 0.00890 𝑐𝑚−𝑠

Reynolds Number = 65883.18166

(4𝑐𝑚)

Table 4. Summary of Result in Experimental Values Head Trial No.

Loss (cm)

Discharge

Velocity

Analytical

Reynolds

Flow

(cm3/s)

(cm/s)

Friction Factor

number

Regime

1

94.5

1044.776119

83.14064188

0.3576372954

37366.58062

2

107.1

1166.666667

92.8403835

0.3268734083

41726.01506

3

157.5

2187.5

174.075719

0.1359696258

78236.2782

4

69.3

833.3333333 66.31455962

0.4122429093

29804.29646

5

144.9

1842.105263 146.5900792
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