Fundamentals of Thermal-Fluid Sciences
Fundamentals of Thermal-Fluid Sciences
5th Edition
ISBN: 9780078027680
Author: Yunus A. Cengel Dr., Robert H. Turner, John M. Cimbala
Publisher: McGraw-Hill Education
bartleby

Videos

Question
Book Icon
Chapter 14, Problem 95RQ
To determine

The pressure drop across a single tube and power required by the pump and the reduction in flow rate due to scaling.

Expert Solution & Answer
Check Mark

Explanation of Solution

Given:

Diameter of the tube is 1cm.

Length of the tube is 1.5m.

Temperature of water is 60°C.

Rate of flow is 15L/s.

Number of brass tubes is 80.

Calculation:

Refer Table A-15 “Properties of saturated water” from Appendix 1 and obtain the following properties of ammonia.

  Density,ρ=983.3kg/m3Dynamic viscosity, μ=0.467×103kg/ms

Calculate the velocity of the flow.

  V=V˙Ac=15L/s×1 m31000 L80×π4×(1×102m)2=2.387m/s

The Reynolds number is

  Re=ρVDμ=(983.3kg/m3)(2.387m/s)(0.01 m)0.467×103kg/ms=50270

Since the Reynolds number is greater than 2300, the flow is turbulent. Hence, the friction factor is obtained from Moody chart as follows:

  1f=2.0log(ε/D3.7+2.51Ref)=2.0log[1.5×106m/0.01 m3.7+2.5150270f]

On solving the above equation, we get f=0.0214.

Calculate the pressure drop.

  ΔP=fLDρV22=0.0214×1.5 m0.01 m×(983.3kg/m3)(2.387m/s)22=8992 Pa=8.992 kPa

Thus, the drop in pressure across a single tube is 8.99 kPa.

Calculate the power required by the pump.

  W˙pump=V˙ΔP=(15L/s×1 m31000 L)(8.99 kPa)=0.135 kW

Thus, the power required by the pump is 0.135 kW.

After the buildup of scale:

The velocity of the flow is,

  Vnew=V˙newAc=V˙new80×π4×(8×103m)2        (I)

The Reynolds number is

  Re=ρVnewDμ=(983.3kg/m3)Vnew(0.008 m)0.467×103kg/ms        (II)

The friction factor is obtained from Moody chart.

  1f=2.0log(ε/D3.7+2.51Ref)=2.0log[0.0004m/0.008 m3.7+2.51Ref]        (III)

The pressure drop is,

  ΔP=fLDρVnew22=f1.5 m0.008 m×(983.3kg/m3)Vnew22        (IV)

The power required by the pump is,

  W˙pump=V˙ΔP0.135 kW=V˙ΔP        (V)

We have 5 equations and 5 variables. Solving the system of simultaneous equations, we get:

  Vnew=1.714m/sRe=28870f=0.0723ΔP=19.6 kPaV˙new=6.89L/s

Calculate the reduction in the flow rate.

  Reduction=V˙V˙newV˙=(156.89)L/s15L/s=0.54=54%

Thus, the reduction in the flow rate after scaling is 54%.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
One end of a thin uniform rod of mass m and length 31 rests against a smooth vertical wall. The other end of the rod is attached by a string of length 1 to a fixed point O which is located a distance 21 from the wall. A horizontal force of magnitude F₁ is applied to the lower end of the rod as shown. Assuming the rod and the string remain in the same vertical plane perpendicular to the wall, find the angle 0 between the rod and the wall at the position of static equilibrium. Notes: This quiz is going to walk you through a sequence of steps to do this. It won't give you the answers, but it will hopefully get you to see how to approach problems like this so that you have a working reference/template in the future. This is actually a modified version of a problem from the textbook (6.3). Note that in that problem, is not actually given. It has been introduced for convenience as we move through solving the problem, and should not show up in the final answer. DO NOT DO PROBLEM 6.3. It is…
v
13.64 The shaft shown in Sketch h transfers power between the two pulleys. The tension on the slack side (right pul- ley) is 30% of that on the tight side. The shaft rotates at 900 rpm and is supported uniformly by a radial ball bearing at points 0 and B. Select a pair of radial ball bear- ings with 99% reliability and 40,000 hr of life. Assume Eq. (13.83) can be used to account for lubricant clean- liness. All length dimensions are in millimeters. Ans. Cmin = 42,400 N.

Chapter 14 Solutions

Fundamentals of Thermal-Fluid Sciences

Ch. 14 - Shown here is a cool picture of water being...Ch. 14 - Someone claims that the volume flow rate in a...Ch. 14 - Someone claims that the average velocity in a...Ch. 14 - Someone claims that the shear stress at the center...Ch. 14 - Someone claims that in fully developed turbulent...Ch. 14 - How does the wall shear stress τw vary along the...Ch. 14 - In the fully developed region of flow in a...Ch. 14 - How is the friction factor for flow in a pipe...Ch. 14 - Discuss whether fully developed pipe flow is one-,...Ch. 14 - Consider fully developed flow in a circular pipe...Ch. 14 - Consider fully developed laminar flow in a...Ch. 14 - Explain why the friction factor is independent of...Ch. 14 - What is turbulent viscosity? What causes it? Ch. 14 - Consider fully developed laminar flow in a...Ch. 14 - How is head loss related to pressure loss? For a...Ch. 14 - Consider laminar flow of air in a circular pipe...Ch. 14 - What is the physical mechanism that causes the...Ch. 14 - The velocity profile for the fully developed...Ch. 14 - Water flows steadily through a reducing pipe...Ch. 14 - Water at 10°C (ρ = 999.7 kg/m3 and μ = 1.307 ×...Ch. 14 - Consider an air solar collector that is 1 m wide...Ch. 14 - Heated air at 1 atm and 100°F is to be transported...Ch. 14 - In fully developed laminar flow in a circular...Ch. 14 - The velocity profile in fully developed laminar...Ch. 14 - Repeat Prob. 14–34 for a pipe of inner radius 7...Ch. 14 - Water at 15°C (ρ = 999.1 kg/m3 and μ = 1.138 ×...Ch. 14 - Consider laminar flow of a fluid through a square...Ch. 14 - Repeat Prob. 14–37 for turbulent flow in smooth...Ch. 14 - Air enters a 10-m-long section of a rectangular...Ch. 14 - Water at 70°F passes through...Ch. 14 - Oil with ρ = 876 kg/m3 and μ = 0.24 kg/m·s is...Ch. 14 - Glycerin at 40°C with ρ = 1252 kg/m3 and μ = 0.27...Ch. 14 - Air at 1 atm and 60°F is flowing through a 1 ft ×...Ch. 14 - Prob. 44PCh. 14 - Prob. 45PCh. 14 - Oil with a density of 850 kg/m3 and kinematic...Ch. 14 - Prob. 47PCh. 14 - Prob. 48PCh. 14 - Prob. 50PCh. 14 - Prob. 51PCh. 14 - Prob. 52PCh. 14 - Prob. 53PCh. 14 - Prob. 54PCh. 14 - Prob. 55PCh. 14 - Prob. 56PCh. 14 - Prob. 57PCh. 14 - Water is to be withdrawn from an 8-m-high water...Ch. 14 - Prob. 59PCh. 14 - Prob. 60PCh. 14 - Prob. 61PCh. 14 - Prob. 62PCh. 14 - Prob. 63PCh. 14 - Prob. 64PCh. 14 - Consider two identical 2-m-high open tanks filled...Ch. 14 - A piping system involves two pipes of different...Ch. 14 - Prob. 67PCh. 14 - Prob. 68PCh. 14 - Prob. 69PCh. 14 - Prob. 70PCh. 14 - The water needs of a small farm are to be met by...Ch. 14 - Prob. 72PCh. 14 - Prob. 73PCh. 14 - Prob. 74PCh. 14 - Prob. 75PCh. 14 - Prob. 76PCh. 14 - Prob. 77PCh. 14 - Prob. 78PCh. 14 - Prob. 80PCh. 14 - Prob. 81PCh. 14 - A vented tanker is to be filled with fuel oil with...Ch. 14 - Two pipes of identical length and material are...Ch. 14 - Prob. 84PCh. 14 - Prob. 85PCh. 14 - Prob. 86PCh. 14 - Prob. 87PCh. 14 - Prob. 88PCh. 14 - Prob. 90PCh. 14 - Prob. 91PCh. 14 - Prob. 92PCh. 14 - Prob. 93PCh. 14 - Prob. 94RQCh. 14 - Prob. 95RQCh. 14 - Prob. 96RQCh. 14 - Prob. 97RQCh. 14 - Prob. 98RQCh. 14 - Prob. 99RQCh. 14 - Repeat Prob. 14–99E assuming the pipe is inclined...Ch. 14 - Prob. 101RQCh. 14 - Prob. 102RQCh. 14 - Prob. 103RQCh. 14 - Prob. 104RQCh. 14 - Two pipes of identical diameter and material are...Ch. 14 - Prob. 106RQCh. 14 - Prob. 107RQCh. 14 - Prob. 108RQCh. 14 - Prob. 109RQCh. 14 - Prob. 110RQCh. 14 - Prob. 111RQCh. 14 - Prob. 112RQCh. 14 - Prob. 114RQCh. 14 - Prob. 115RQCh. 14 - Prob. 116RQCh. 14 - Prob. 118RQ
Knowledge Booster
Background pattern image
Mechanical Engineering
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Text book image
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Text book image
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Text book image
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Text book image
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Text book image
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
Intro to Compressible Flows — Lesson 1; Author: Ansys Learning;https://www.youtube.com/watch?v=OgR6j8TzA5Y;License: Standard Youtube License