Chemical Engineering Lab I Manual - SP15

Course Code: CHEN3271

Chemical Engineering Lab I College of Applied Sciences / Sohar

2014 – 2015 LABORATORY MANUAL

Semester: Spring 2015

Tutor: Dr. Hind Done: Dr. Hind Engineering Department(Chemical)

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

PREFACE This lab manual hand out is intended to provide you with a concise guide in respect of CHEN3271 CHEMICAL ENGINEERING LAB I. This is intended to present the basics involved in the subjects of Thermodynamics, Fluid Mechanics and Heat Transfer. This course is the first of a two laboratory courses sequence covering the application of principles of chemical and process engineering: Thermodynamics; Fluid mechanics; Heat Transfer; Experimental planning, data acquisition and safety considerations.

Dr. Hind Barghash

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

LABORATORY DETAILS: Associated Module CHEN3271 Code & Name Level & Semester Level 3 & Semester-Spring Academic Year 2013-2014 Laboratory Name Chemical Engineering Lab I Room(s) No. (A/A22); (T/T05 & T06) Course Assessment Quizzes: 10% Report: 30% Presentation 30% Final exam: 30% Submission Time Objectives

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12th week To understand, operate and acquire hands on experience on experiments such as Jet Impact, Bernoulli principles, Fluid Flow Measurement Devices, Friction in pipes, Head Conduction, Heat convection, Heat Exchangers, Temperature Measurement Bench and Marcet Boiler.

Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

CONTENTS

PAGE NO

GUIDELINES TO TECHNICAL LAB REPORT WRITING

5

IMPORTANT NOTES

11

DISCIPLINARY ACTIONS

12

SAFETY CODE OF PRACTICE

12

INTRODUCTION

13

EXPT NO.

TITLE OF THE EXPERIMENT

.

BASIC HYDRAULIC BENCH

14

1

JET IMPACT

15

2

BERNOULLI PRINCIPLE

21

3

FLUID FLOW MEASUREMENT DEVICES

27

4

FRICTION LOSS ALONG A PIPE

33

MEASUREMENT OF THERMAL CONDUCTIVITY 5

37

OF A METAL NATURAL AND FORCED CONVECTION HEAT

6

TRANSFER FLAT PLATE AND FINNED PLATE

7

HEAT EXCHANGERS

50

8

TEMPERATURE MEASUREMENT BENCH

59

9

MARCET BOILER

62

REFERENCES

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Guidelines to Technical Lab Report Writing In engineering, one of the major forms of communication is the technical report. This is the conventional format for reporting the results of your research, investigations, and design projects. The ability to produce a clear, concise, and professionally presented report is a skill you will need to develop in order to succeed both at the university and in your future career. Scientists are investigators who "try out" ideas. They conduct experiments in order to test or prove ideas, and they share the results of their experiments in papers and written reports. Reports allow others to learn the results of scientific investigations. Like other scientists, you will be conducting experiments, stating hypotheses, observing processes, recording data and formulating conclusions. You will be asked to write lab reports describing these experiments, summarizing your observations and explaining your conclusions or judgments about the meaning of what you observed. Although, the reports vary in the type of information they present (for example, original research, the results of an investigative study, or the solution to a design problem), all share similar features and are based on a similar structure. Students need to know how to write a report. When writing a technical report, do not assume that the audience knows what you know.

General Format Lab reports and papers must be typed or word-processed. They should include tables and illustrations where necessary. Any report must have certain content to accomplish the purpose of the experiment: title page, abstract, table of content, objectives, introduction, equipments, methods and experimental procedure, results, discussion, conclusion, references, and appendices.

1- Title (cover) page The first page of the report is the title page. Include the title of the report, your name, the course number, your section number, the instructor's name, and the date the report is

due. Note that the title is a one line explanation of your experiment. 2- Abstract: A brief description of the experiment should be given. This should include the method and a summary of the findings. It should not be more than half a page. It is recommended to write it after the report is completed in order to be able to include all important aspects and findings of the experiment.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

3- Table of Content Table of content Objective Introduction Equipments Method and Experimental Procedure Results Discussion Conclusion References Appendices

page 1 2 3 4 5 6 7 8 9

4- Objectives: Explain the purpose of the experiment in order to show why you undertook the experiment. However you may have more than one objective to be achieved.

5- Introduction Introduction should include general statements familiarizing the reader with the problem under study, the laboratory techniques used, and the experimental objectives to be obtained. The purpose of the experiment should be clearly outlined in this section. It should show the necessity for the experiment through theory and past work. Usually the Introduction is one to two paragraphs and a maximum of one page is sufficient for this section. The text of the report begins with an introduction. In this section of the paper, identify the experiment(s). In general terms, tell the reader what you intend to do and why you intend to do it. Include all phases of the experiment(s). Emphasize any unusual or critical conditions. Point out exactly what ideas or principles you are investigating. Make sure the reader understands the purpose of the experiment(s). What you are attempting to test, prove, or investigate should be clear to the reader. If necessary, include general information that explains the importance of the experiment(s) and why you are doing this project.

Tie the experiment to your general course of study by explaining how it confirms or fails to support the general laws of chemistry you are exploring and learning. Even though you are acting as the "expert" for the general reader, you must cite references both to support statements you make about the scientific basis for your investigation and to define sources for specific pieces of data crucial to the experiment. Citations give you credibility: they tell the reader that you have prepared properly for the experiment by providing yourself with a basic background and by "checking out" the

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2015 Spring Semester

accepted authorities. These citations should be numbered consecutively in the text and listed in the References Section (see References at the end of this section). Typical sources for your citations include your textbook, other lab manuals you may have consulted, tables of data such as the CRC handbook, chemical catalogs, and internet resources 6- Equipments A list of the materials that need it to do the experiment must be listed in this part. The experimental setup or laboratory apparatus required is to be mentioned. This includes the diagram of experimental setup.

7- Method and Experimental Procedure In this part of the report, you give the reader a step-by-step account of the actual experiment. Here, you will do more than simply provide greater detail about the experiments and the materials used than you did in the Introduction. You need to describe your procedures in such a way that others could read your lab report, follow your lab procedure, and successfully duplicate your experiment. Scientific experiments are not considered valid unless they can be repeated by other experimenters working in other laboratories. In one sense, science has no secrets: scientific theories become established only when the experiments that led to them can be repeated or verified by others besides the original investigators. You make this verification possible when you write a complete, accurate description of your experiment. Scientists also use lab reports as a means of learning and sharing techniques. Other investigators may not choose to duplicate your experiment, but they may choose to use your procedure in some similar investigation. The experimental section of your lab report should be usable as a set of directions for other scientists.  A word about style --As you are writing, pay close attention to your style. The personalities of you and your lab partners (if you have any) are not important to the report. In scientific papers, facts and interpretation of facts count more than personalities, so the

depersonalized writing known as "scientific" or "academic" is most appropriate to your lab report. What are the common elements of this style?  U s e the past tense. You are writing about the experiment you have already completed – not one that you are now doing.  U s e the third person and passive voice. In a sense, you are telling a story; in another sense, you are providing directions. Rather than telling a story or writing a 7

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2015 Spring Semester

recipe, you must describe what you did. At the same time, keep the personal element out of the report. For example:

Write: Not: Nor:

The solution was filtered. I (we) filtered the solution. Filter the solution.

 B e as accurate and specific as possible. Successful scientific description requires exact detail. Note: The style used in scientific reports is quite different from that required for an English paper. It is important that you understand and get used to using different writing styles appropriately. The experimental section can be placed after the introduction if you wish, however, you will avoid the trap of discussing results if you place it last as it is found in most chemistry journals.

8- Results It includes all the findings obtained from the experiment, usually in the form of graphs. All figures should be numbered and titled at the bottom. The coordinates should be defined with proper scale and units. The students may be asked to present their inference or interpretation of the results. In some cases, students may be asked to present their understanding of the purpose of the experiment carried out. In this section, you summarize the outcome of your experiments for your reader. This section will consist primarily of data (facts and figures) that you gathered in the course of the experiment. Read the section of the lab manual on reporting numerical results. Data must be presented in such a way that it is easy to read. You must organize or assemble and label the data for the reader. Numerical data or lists of numbers are usually presented in tables. Relationships between sets of data or factors in the experiment are often shown in graphic form. Graphs, drawings, and sketches are called figures. Although tables and figures are labeled on the page with descriptive titles, they are identified in the written body of your report by number rather than name. When you discuss tables and figures in the text of this section, you mention Table 1, Table 2, Figure 1, and so on. The table's title should be at the top of the table, whereas, the figure's title should

be below the figure. Place tables and graphs at appropriate points in the body of your report. This makes it easy for the reader to use and understand the graphs, charts, tables, etc. If you put the data presentation in a separate appendix, the reader will have great difficulty in understanding the results of your experiment. It is permissible to have one large section called Results and 8

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Discussion. In this section, the results are presented in tables, graphs and charts, and then discussed in a block of text immediately following. In summary that Results section should include the following:a. Data (i.e the measurements, the numbers…) b. Graph plotting, (Include charts, graphs and any other pictorial representation of the numerical data that you collected c. Data Analysis ( i.e calculation )

9- Discussion This is the most important part of the report. The presented results should be interpreted in view of the theoretical background. It should explain why the phenomena look as shown. Show how close the experiment was to the theory and indicate the sources of error which lead to disagreement between experiment and theory. The discussion section of your report is the most important one for you and your reader. In this section of the report, you interpret the results of your experiment for the reader. You explain what the results mean, and you mention any weaknesses or problems in the plan of the experiment or methods you used. You demonstrate not only how successful your experiment was but also how well you understood the experiment. The discussion section can be difficult to write, but you will learn more about your experiment and yourself as an investigator as you write it. Before you begin writing this section, complete the Introduction, Experimental section and the Results. Put these sections on the desk together with your lab notebook so that you will be able to look at all these sources of information as you write the Discussion section. Then prepare to write a rough draft of this section. You can make an outline for yourself by taking the following steps. 1. Write out your ideas and goals again. Look over the tables, figures, and general information you compiled for the Results section. What did your experiments show? 2.

Write down the specific data that led you to decide that your hypotheses were correct (or incorrect). List all the data, including actual information you recorded during the experiment.

3. Write down what you know about the principles involved in your experiment. How do the results of your investigation fit with accepted law? Identify the sources of your information at this point.

4. List any weaknesses or problems you discovered in your experimental design or procedure. Tell the reader how these problems may have affected the

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

results of your experiment. 5. Review the experiments again. List and discuss any difficulties that arose during the course of the experiment. Be sure to point out to the reader any way in which these problems could have affected the outcome of the experiment. Using this list as a guide, prepare a comprehensive discussion or explanation of the results of your experiment.

10- Conclusion This should tell the reader in brief what was covered in the experiment and what the most important results were. Your overall conclusions about the report have probably already been mentioned several times in the course of your report. You may have predicted some of the outcomes of your experiments in the Introduction and discussed them again as an empirical conclusion (meaning that it was derived from your experiments and observations) in the Results section. In the Conclusion section, a brief, single paragraph may be enough to clearly state the outcome of your investigation. The Conclusion Section tells the reader what the results of the experiment mean. In a sense, it is a summary of the Results and Discussion sections combined. Make sure your stated conclusions clearly match the actual outcome of your experiment(s). 11- References The final section of your report tells the reader where to find any of the sources of information you used in your report. In the body of your report (particularly in the Discussion section), you may have mentioned other texts in theory or elsewhere. Each of these references should be numbered consecutively within the text as superscripts at the place where they were used. At the end of your report, after the Conclusion, include a complete reference list, in numerical order, of the sources used. The reader can use this list to follow up or check out any source you mentioned or to do additional reading. The format of the references should follow the American Chemical Society Guidelines, which can be found in the ACS Style guide. For example: "A similar experiment has been reported by Haight1 , and expanded by Vogel2 ." 1- Haight, G.P. J. Chem. Educ. 1965, 42, 468. 2- Vogel, A. I. A Textbook of Qualitative Inorganic Analysis, Longman: New York, 1979, p358 In general the format to be used is: For journals: Author (last name, initials), title (in italics), year (bold), volume number

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

(italics), starting page number. For books: Author (last name, initials), title (in italics), and publisher: city, year, page number. For multiple authors, separate the authors by a semi colon, e.g., Brown, H.C.; Corey, E. J; Cram, D. J. J. Irrep Res, 1990, 21, 991 For further information, see Dodd, J. S. Ed. The ACS Style Guide, A Manual for Authors and Editors, American Chemical Society, Washington DC, 1986.

Internet Resources If you find a reputable resource on the internet then you may also cite that as a reference. Be careful in the sites that you visit; try to stay with sites hosted by professional societies, the government or other reputable institutions. When citing an internet site you should give the URL, the host institution, and the date of your visit to the site (since many internet sites are transient) For example “SuperChemLab” http://chemed.eng.clemson.edu/SCL/index.html Clemson University (January 1, 2002). 12- Appendices: The appendix should contain information that is required, but would be distracting from the normal flow if included in the main body of the report. This might be raw data (date collected from the experiment), lab notebook pages, regression summaries, or sample calculations using the equations stated in the theory.

IMPORTANT NOTES:  Be concise to the point in writing your report. Extra words actually distract from the sought meaning.  Use visual aids. Writing a technical report is more than common prose writing.  Each graph, figure, or table should have a title and a number.  All pages should be numbered except the cover page.  All reports should be typed and checked for spelling and grammatical errors.  Use the past tense at all times unless it’s truly awkward.  Avoid using I, we, you, etc. while writing the report.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

DISCIPLINARY ACTIONS:  Any absent student cannot re-do the experiment without an acceptable reason. Private hospitals/clinics sick leave is not acceptable.  Any delay or late submission of the reports will be punished (5% reduction for every day of delay).  Students may be refused entry to the lab if he/she is late by more than 5 minutes.  Copying or forging of report materials is strictly prohibited and will be severely punished.

LAB SAFETY INSTRUCTIONS:  No eating, drinking, smoking, or chewing of gum is permitted in the work area. Contamination of food, drink, and smoking materials is a potential for exposure to toxic substances.  Work in the lab, only when the teacher or lab instructor/supervisor is present or when you have permission to do so.  Ask for and familiarize yourself with all manuals, resources and guidelines for working in your school's laboratories. These include safe work procedures, chemical safety information, laboratory equipment safety information and links to other resources. If you have any questions in preparation, do not hesitate to ask for updated or missing information;  Learn the location and proper usage of the eyewash fountain, fire extinguisher, safety shower, fire alarm box, office intercom button, evacuation routes, cleanup brush and dust pan, glass/chemical disposal can and any additional safety equipment including evacuation procedures;  Report all accidents regardless of how minor to your teacher or lab instructor/supervisor including contact with chemicals and minor burns, spills, etc.  Keep a focus on your experiments; do not play, joke, distract others, or engage in behavior that could lead to injury of yourself or others.  Before beginning work in lab, prepare yourself with a thorough understanding of the instructions, objectives of the experiment, and understanding of the materials  Begin with a clean work surface with your instructions clearly posted and available; have a clear, clean work space and eliminate unnecessary books, book bags, equipment, etc.  Use goggles and lab aprons as instructed; wear appropriate clothing and avoid loose fitting garments that can cause spills as well as open-toed footwear or sandals.  Use care when accessing or transporting stock chemicals and only under supervision  Use equipment only as directed;  View the contents of experiments from the side; never directly into an experiment as in a test tube.  Carefully smell experiments using your hand to "fan" the odor or fumes towards you and only when instructed to do so. Never directly above or in the container.  Never taste or ingest chemicals or materials in the lab; do not bring food, drink and gum etc. into the lab area;  Return all lab materials and equipment to their proper places after use as instructed; clean your lab space as instructed by your teacher or lab instructor/supervisor.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

INTRODUCTION: In view of the importance attached to practical work in mechanical laboratories, the following rules must be observed. 1. Before commencing any experiment, read the machine instruction and programming regarding the concerned experiment. 2. Before starting work, make sure you have a clear idea of what you have to do and also the precautions to be adopted. 3. At the beginning of each experiment, you will find a list of tools required. Check whether all the articles are in good condition. If you have any doubts about any of the tools supplied, ask the instructor. 4. Carry out the operations methodically and in the order given. Record all the observations madesheets have been provided for this purpose in the lab manual at the end of each experiment.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Basic Hydraulics Bench The Basic Hydraulics Bench unit HM 150 shown in Fig. 0.1 provides the basic services for the pumping and volumetric measurement of the water supply with which all the additional accessories and experiments are used. The working surface of the unit is in fibreglass, moulded to provide a recessed area on which to mount experiments. An integral weir tank is provided along with a volumetric measuring tank. The entire unit is self-contained and mobile.

Fig. 0.1: Hydraulics bench unit HM 150 The measuring tank [4] is stepped to enable for accurate measuring of both high and low flow rates. A level indicator [3] allows convenient read out of the flow. The measuring tank discharges into a fiberglass sump [1]. Materials used in the bench construction and its modules have been selected in order to minimise corrosion problems. An electric motor drives a submersible motor driven pump [11] which delivers water to the outlet at the working surface for connection to the individual experiments. To determine volumetric flow rate use stopwatch to establish the time Δt required for raising the level in the volumetric tank of the HM 150 from 20 ltr to 30 ltr. a) Close the outlet valve. b) Read the actual volume at the remote sight gauge. The volume flow-rate is calculated as: V V t

(0.1)

Where ΔV and Δt are, respectively, the actual volume and time measured. For low volumetric measurement use the 2 ltr measuring cup.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No. 1 Jet Impact Objective: The main objective of this experiment is to measure the force exerted by water jet impinging on objects with different geometry (e.g. flat plate, hemisphere, etc.) and compare measured values of the impact forces with theoretical prediction based on the principle of linear momentum. Theory: If a vertical water jet moving with velocity w1 is made to strike a target, which is free to move in vertical direction, force will be exerted on the target by the impact of the jet. The jet force can be calculated theoretically from the principle of linear momentum (or Newton's second law). For Plate (90o deflection):

Fth  ̇ ..(w1  w2 ) If w2 = 0 then

Fth  ̇ ..w1

(1.1)

For hemisphere (180o deflection):

Fth  ̇ ..(w1  w2 ) If w2 = -w1 then

Fth  2. ̇ ..w1

(1.2)

For Slope:

Fx  ̇ .. w1 .cosα Fth Fx .cosα Fx  ̇ .. w1 .cos2α

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with α = 45º (1.3)

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

For Cone:

Fth  ̇ ..(w1  w2x ) w2 = -w1 . cosα

with α = 45º

w2x = w2 . cosα Fth  ̇ .. w1 .(1+ cos2α)

(1.4)

The velocity w1 of the jet from the nozzle is calculated from the volumetric flow and the cross-sectional area AD of the nozzle. (1.5)

(1.6)

d is the nozzle diameter (d = 10 mm = 0.01 m)

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2015 Spring Semester

Apparatus: The Impact of jet unit HM150.08 (Fig. 1.1) is designed to investigate jet forces impacting against stationary deflectors. The impact forces are produced by a water jet. The impact forces are measured using a lever mechanism and loading weights. The impact forces of the water jet are set via the flow rate. Water is supplied from the HM150 basic flow module which enables a closed water circuit to be constructed and allows volumetric flow measurement.

Fig. 1.1: Impact of jet apparatus HM150.08 The Impact-of-jet unit HM150.08 essentially consists of: – Base Plate [7] – Inlet connection [8] – Drain connection [6] – Perspex vessel [5] – Nozzle [4] – Deflector [3] – Lever mechanism [2] – Loading weights [1] Various deflectors can be fitted at position [3]: – Flat Plate – Hemisphere – Slope – Cone In this experiment, Four plates (the Flat Plate , the Hemispherical Plate, the Slope Plate , and the Cone Plate) will be considered. 17

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Test procedure: – Place the test set-up on the HM150 so that the drain routes the water into the channel. – Fit connecting hose between HM150 and unit. – Open HM150 drain. – Assemble deflector [1], (Plate, Hemisphere, Slope or Cone ). Loosen the 3 screws [3] on the cover [4] and remove cover together with lever mechanism. Fit appropriate deflector. Do not forget to tighten lock nut [2] on rod. Screw cover back onto vessel. – Use adjusting screw [5] to set pointer to zero (zero notch [7]). When doing so, do not place any loading weights on measurement system [8]. – Apply desired loading weight [8] 0.2N; 0.3N; 1N; 2N; 5N or combinations thereof. – Close main HM150 cock. – Switch on HM150 pump. – Carefully open main cock until pointer is on zero again. – Close HM150 drain cock. – Determine volumetric flow. This involves recording time t required to fill up the volumetric tank of the HM150 from 20 to 30 litres. – Add loading weights and note down time t for 10 litres. – Switch off pump, open drain. Measurements: Record the following measurements: a. Flat plate:

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2015 Spring Semester

b. Hemisphere:

C. Slope:

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2015 Spring Semester

d. Cone:

Results and calculations: For each of the four objects considered in the experiment, prepare a table that compares the theoretically calculated force from the linear momentum equation (Equation 1.1 - 1.4 with the force actually applied. Table 1.5: Calculated and measured forces for - - - - - - - - - - - - - - Flow rate ̇ in ltr/s

Velocity w1 in m/s

Calculated Force Fth in N

Measured Force F in N

In the above table, the velocity w1 is obtained by dividing the measured volumetric flow by the crosssectional area AD of the nozzle according to Equations (1.5) and (1.6). Note that the nozzle diameter (d) in Equations (1.5) and (1.6) is 10 mm or 0.01 m. In order to compare theory (Equations 1.1 - 1.4) with observation, plot a graph showing measured force (F) against the theoretical force as obtained from Equations 1.1 for the flat plate or Equation 1.2 for the hemispherical plate or Equations 1.3 & 1.4 for slope and cone respectively. For all cases, a linear relationship between the two forces is anticipated. Discussion & Conclusions Discuss your results and explain any possible sources of inaccuracy in the experiment. Which of the four deflectors (flat plate, hemispherical plate, slope plate and cone plate) required a higher jet velocity to lift the same weight and why? Give your conclusions. 20

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2015 Spring Semester

Experiment No. 2 Bernoulli's Equation

Objective: The objective of this experiment is to validate Bernoulli equation which states that the sum of the piezometric pressure (p + γz) and kinetic pressure (ρw2/2) is constant along a streamline for the steady flow of an incompressible, inviscid fluid. Theory: The Bernoulli equation, which is one of the most widely used equation in the analysis of fluid flow, is derived from application of Newton’s Second Law to a differential fluid element aligned with a streamline. It relates pressure, elevation and velocity between any two points along a streamline in a flow field that is inviscid, steady, and constant density. The equation states that:

2

where p is the pressure, γ the specific weight (γ = ρg), z the height, and w is the velocity of the fluid. The first term on the left hand side of Bernoulli’s equation is the pressure head, the second is the elevation head and the third is the velocity head; pressure head plus elevation head is called static head while velocity head is also referred to as dynamic head (static head plus dynamic head is total head). Each term in the equation has the dimension of length and H is called "the total head". Velocity calculation based on Bernoulli Equation For incompressible fluids such as water γ is constant and if the height z is also constant, Bernoulli’s equation becomes:

2

2

Replacing (p1/γ) and (p2/γ) by the respective static pressure heads h1and h2 yields:

Where,

By measuring the static head (h) using a manometer and the total head (H) using a pitot static probe, Equation (2.3) can be used to determine the velocity at any section i according to:

Note that the difference between the total head (Hi) and static head (hi) is the dynamic head at section i. 21

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Velocity calculation based on Continuity Equation Equation (2.4) gives the velocity at any section as obtained from Bernoulli equation. However, the velocity can also be obtained from the continuity equation (the conservation of mass principle). If the mass flow rate is constant in the system: Given:

And,

Therefore, . In general, the velocity at any section i can be determined from that at section 1 from:

Where, wi  A1 / Ai . By measuring the velocity w1, Equation (2.7) can be used to determine the value of wi from the respective value of wi given in Table 2.1. The value of wi thus obtained can be compared with the corresponding value calculated from Equation (2.4) which is based on Bernoulli equation. Determination of Flow Rate Factor A Venturi nozzle can be used for flow rate measurements.In comparison with orifice or nozzle,there is a far more smaller pressure loss during measurements of flow rate. The pressure loss Δp between largest and smallest diameter of the tubeis used as measure for the flow rate: (2.8)

The flow rate factor K is generally made available for the user by the manufacturer of a Venturi nozzle.If the flow rate factor is unknown, it can be determined from the pressure loss Δp:

(2.9)

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2015 Spring Semester

The pressure loss is read off from the 6-fold manometer in mm water column and set in the equation as bar. The flow rate can be used with unit l/s.

Apparatus:

Fig. 2.1. Bernoulli equation demonstrator HM 150.07

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2015 Spring Semester

Experiment procedure: Arrange the experimentation set-up on the HM 150 such that the discharge routes the water into the channel • Make hose connection between HM 150 and HM 150.07 • Open discharge of HM 150 • Set cap nut (1) of probe compression gland such that slight resistance is felt on moving probe • Open inlet and outlet valves • Switch on pump and slowly open main cock of HM 150 • Open vent valves (2) on water pressure gauges • Carefully close outlet valve until pressure gauges are flushed • By simultaneously setting inlet and outlet valve, regulate water level in pressure gauges such that neither upper nor lower range limit (UL, LL) is overshot or undershot • Record pressures at all measurement points. Then move overall pressure probe to corresponding measurement level and note down overall pressure • Determine volumetric flow rate. To do so, use stopwatch to establish time t required for raising the level in the tank of the HM 150 from 20 l to 30 l. Results and calculations: Results: Record the following measurements at each of the six point, the volume flow rate and the time: i

h1

h2

h3

h4

h5

h6

[mmWS]

[mmWS]

[mmWS]

[mmWS]

[mmWS]

[mmWS]

Static head Total head Volume flow (l) Time (s)

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Calculations- Velocity Profile in the Venturi Nozzle: The Venturi nozzle (5) has six measurement points. Table 2.1 shows the areas and the standardised reference velocity w at the six points. Table 2.1. Geometry of the venturi nozzle

The reference velocity

is derived from the geometry of the Venturi nozzle according to

(note that w = 1 at both point 1 and point 6). Multiplying the reference velocity values with a starting value, the velocities at the six measuring points of the Venturi nozzle can be calculated from Equation (2.7). At constant flow rate, the starting value for calculating the theoretical velocity is found as: (2.10) Where the area A1 is given in Table 2.1 and the volume flow rate ̇ is measured using the Basic Hydraulics Bench HM 150 from Equation (0.1). Calculate the velocity at the six points as obtained from Equation (2.4) and from Equation (2.7) from the measured values as shown in table below and plot the two velocities.

i

h1

h2

h3

h4

h5

h6

[mmWS]

[mmWS]

[mmWS]

[mmWS]

[mmWS]

[mmWS]

Static head Total head Dynamic head wi from Eq. (2.4) wi from Eq. (2.7)

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Calculation of Flow Rate Factor The following table shows the pressure loss for various flow rates as well as the flow rate factor K.

1 3

Discussion & Conclusions Discuss your results and explain any possible sources of inaccuracy in the experiment. Give your conclusions.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No. 3 Flow measurement Objective: In this experiment, the students will be exposed to different flow measurement techniques. The flow measurement unit, which includes three different flow meters (rotameter, orifice/nozzle, and venturi tube), allows the students to compare the measuring principle and accuracy of different flow meters. Theory: Rotameter The rotameter consists of a vertical conical measuring section, through which the liquid flows from bottom to top. A specially shaped float with a density that is normally only slightly greater than that of the liquid, moves freely in the liquid flow and is carried along by the flow due to its flow resistance. This results in equilibrium between the weight of the float on the one hand and its drag and lifting force on the other. The float adjusts to a particular height in the measuring tube depending on the flow volume. This height indicates the rate of flow. Because of the operating principle, a reliable measuring range on a rotameter never begins at zero, but at ~5 - 10% of the final measuring value. Orifice and Nozzle The orifice and nozzle are what is known as the throttle devices. They both represent a constriction in a tube. The reduction in cross section results in an increase in the speed of the flowing medium. This is associated with a pressure loss Δp between the normal tube cross section AD before the inlet and the constricted tube cross section Ad at the orifice or nozzle. This pressure loss Δp is a measure of the volumetric flow. The pressure conditions in the Venturi tube follow Bernoulli’s Law. According to this law we can obtain the following relationship between pressure difference Δp (recorded using measuring connections) and volumetric flow ̇ :

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Chemical Engineering Lab 1 Manual – CAS Sohar Note: In the above equation ̇  k. p we must use Δp in mbar.

2015 Spring Semester (3.1)

This type of measurement is extremely accurate, but the orifice or nozzle have a comparatively high flow resistance. Throttle devices are very sensitive to disturbances in the inlet and outlet flow. Elbows, T-pieces, valves, gate valves or similar fittings must therefore be installed sufficiently far away from the throttle device. Venturi tube The Venturi tube is also a throttle device. In this case, the constriction of the tube cross section is split into three different areas. The inlet corresponds to a nozzle, followed by a straight section and finally a diffusor with a defined extension angle ψ. The pressure loss Δp between the normal tube cross section AD before the inlet and the constricted straight section Ad is significantly less than with the orifice or nozzle. As for the orifice and nozzle, from Bernoulli equation we can obtain the following relationship between pressure difference Δp and volumetric flow ̇ :

Note: In the above equation ̇  k.

 p we must use Δp in mbar.

(3.2)

Apparatus: The Basic Principles of Flow Measurement Unit HM 150.13 shown in Fig. 3.1 comprises three different flow meters: a Venturi tube (3), an orifice and a nozzle (4), and a rotameter (5). The flow rate can be regulated using the ball valve (6). The pressure losses at the measuring elements can be recorded using pressure connections with rapid action couplings. The connections are connected to a 6-tube manometer (2), which is fitted with a ventilation valve. The unit is designed to be used in conjunction with the basic fluid mechanics module HM150, which provides the water supply and allows volumetric flow measurement. Accuracy of the three measuring devices can be assessed by comparing their measurements of the volumetric flow with that measured by the HM 150.

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Chemical Engineering Lab 1 Manual – CAS Sohar

1 Base plate with frame 2 Multi-tube manometer 3 Venturi tube 4 Flow meter with orifice or nozzle 5 Rotameter

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6 Ball valve for inlet 7 Water inlet 8 Water outlet 9 Pressure measuring connection

Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Fig. 3.1. Flow measurement unit HM 150.13 Six-tube manometer The 6 tube manometer has 6 glass cylinders with a mm scale (1) for measuring the water column (WC). The unit mmWC is often used here (10mm WC = 1 mbar). - Measuring range 390 mmWC - All the tubes are connected to one another at the upper end and ventilated by a shared ventilation valve (2). The measuring connections (3) are at the lower end. - Differential pressure measurements are carried out with the ventilation valve closed (2), absolute pressure measurements with the ventilation valve open (4). Standard pressure unit: Pascal (Pa) 1 Pa = 1 N/m2 = 10-5 bar = 0.01 mbar

Test procedure: Orifice / nozzle - Prepare the HM150 and the HM150.13. - Insert either the orifice disc or the nozzle disc into the housing (4) and fit the housing in the tube system on the HM150.13. - Connect the pressure connections on the housing to two measuring tubes on the pressure gauge (2). - Prepare the pressure gauge (2) for differential pressure measurement. - Switch on the pump on the HM150. - Open the adjusting valve (6) on the HM150.13 and initially set a low flow rate. - Note the volumetric flow ̇ displayed on the rotameter in a table (see end of section for table template). - Note the differential pressure value on the pressure gauge in the table. - Repeat the previous steps for further settings of the adjusting valve (6) on the HM150.13. Venturi tube - Prepare the HM150 and the HM150.13. - Connect the pressure connections on the Venturi tube (3) to two measuring tubes on the pressure gauge (2). - Prepare the pressure gauge (2) for differential pressure measurement. - Switch on the pump on the HM150. - Open the adjusting valve (6) on the HM150.13 and initially set a low flow rate. - Note the volumetric flow ̇ displayed on the rotameter in a table (see end of section for table 30

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

template). - Note the differential pressure value on the pressure gauge in the table. - Repeat the previous steps for further settings of the adjusting valve (6) on the HM150.13. Measurements : Orifice/ Nozzle

Venturi tube

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Results and Calculations The flow coefficients for the orifice and nozzle to be used in conjunction with Equations (3.1) and (3.2) are as shown below.

For the orifice/nozzle plot the flow values recorded against the associated differential pressure values in a graph. This gives the relationship between pressure loss Δp and volumetric flow ̇ as a root function.

Discussion and conclusions Based on your results and by drawing the necessary graphs: 1. Compare the accuracy of the different devices used in the experiment. 2. Compare the head loss through each throttle device. 3. Draw the calibration curve for the rotameter.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No. 4 Friction loss along a pipe Objective: In this experiment, friction losses in pipe flows are studied by measuring the pipe friction factor as a function of the Reynolds number. The pipe friction factors evaluated experimentally will be compared with the pipe friction coefficients obtained theoretically for both laminar and turbulent flows. Theory: For fully developed flow in a pipe, the head loss due to friction ( hv ) is given by the Darcy-Weisbach formula:

Where

 d l

 w

Pipe friction factor Internal diameter of pipe section (3 mm = 0.003 m)) Length of pipe measuring section (400 mm = 0.4 m) Density of flowing fluid (for water the density is 998 kg/m³) the flow velocity (m/s)

Accordingly, the pipe friction factor (λ) can be determined by measuring the pressure drop due to friction in the pipe as follows: 2 hv d (4.2)    l  w2 The pipe friction factor (λ) obtained from Equation (4.2) can be compared with the theoretical pipe friction coefficient (λth) for laminar and turbulent flows. For laminar flow:

th 

64 Re

(4.3)

th 

0.3164 4 Re

(4.4)

For turbulent flow in smooth pipe:

The Reynolds number (Re) is calculated from: w.d Re   Where,  is the kinematic viscosity of medium [m2/s].

(4.5)

NOTE: Since the unit for hv in Eq. (4.1) is [Pa], when calculating the pipe friction factor λ using equation (4.2), the measured head loss in cmWS must be converted into a differential pressure in [Pa] and inserted into the formula. Conversions: 1 cmWS = 1 mbar = 100 Pa 33

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Apparatus: The HM 150.01 experimentation stand is used to investigate pipe frictional losses with laminar and turbulent flows. The pipe section is a brass pipe with an internal diameter of 3 mm. The distance between the pressure measuring fittings and thus the length of the experimental pipe section is 400 mm.

Figure 4.2: Pipe friction apparatus HM 150.01 1. 2. 3. 4. 5. 6. 7.

Instrument panel Drain valve Pressure measuring fitting Water manometer Dial manometer Head tank Shut-off valve for water feed at bypass

8. Bypass 9. Hose connection for water inlet 10. Shut-off valve for water inlet on head tank 11. Shut-off valve for water outlet on head tank 12. Pressure measuring fitting 13. Pipe section

Head loss measurement The head loss hv is adjusted using the drain valve (2) and measured on the water manometer (4) (see Fig. 4.1): hv= h1- h2 h1 h2

34

(4.5)

Static pressure head at pipe inlet [mm] Static pressure head at outlet [mm]

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Velocity measurement The volumetric flow ( ̇ ) is measured using a measuring tank and a stopwatch. The flow velocity is calculated from:

Where

̇ is the measured volume flow rate and A is the cross-sectional area of pipe

2

Test procedure A. Laminar flow – Connect the hose connection (9) for the water supply from the HM150.01 to the HM150 Basic Hydraulics Module. – Connect the water manometer (4) to the two pressure measuring fittings (3; 12). – Open the shut-off valve at the drain (2). – Close the valve (7) on the bypass. – Open the valves (10) and (11) on the head tank. – Turn on the pump on the basic hydraulic unit HM150 and adjust the valve controlling the flow such that a constant water level is established at the head tank overflow (6). Fine adjustment can then be carried out using the shut-off valve (10). – Regulate the flow using the shut-off valve at the drain until the water manometer shows a constant pressure difference of 2 cm WS. This corresponds to the head loss hv. – Then measure the volumetric flow using a measuring tank and a stopwatch. – Continue the experiment by increasing the flow in increments (hv rises) and repeating the head difference and volumetric flow measurements. – Note the measured values. Caution! While performing the experiment, make sure that the water level in the head tank remains constant. B. Turbulent flow The head tank is not used for this experiment. A higher flow velocity is required for turbulent flow. The water is therefore fed directly from the HM150 into the pipe section (13) via a bypass (8). – If not already connected, connect the hose connection (9) for the water supply from the HM150.01 to the HM150 Basic Hydraulics Module. – Connect the dial manometer (5) to the two pressure measuring fittings (3 and 12). – Open the shut-off valve at the drain (2). – Open the valve (7) on the bypass. – Close the valves (10) and (11) on the head tank. – Turn on the pump on the HM150 and adjust the valve controlling the flow such that a constant flow is established. – Regulate the flow using the shut-off valve (2) at the drain until the dial manometer shows a constant pressure difference, e.g. 50 mbar. – Then measure the volumetric flow using a measuring tank and a stopwatch. – Continue the experiment by increasing the flow in increments (Δp rises) and repeating the pressure difference and volumetric flow measurements. – Note the measured values.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Measured values: A. Laminar flow hv (cm)

Δp (mBar)

t (s)

̇ (l/s)

V (l)

w [m/s]

Re

λ

λth

2 3 4 5 6 8 12

B. Turbulent flow Δp (mBar) 50 100

t

( s )

V (l)

̇ (l/s)

w [m/s]

Re

λ

λth

125 150 175 200 225 240 Data presentation - Calculate the measured and theoretical values of the friction factor and Reynolds number (Re) for both laminar and turbulent flows at the different fluid velocities. - Plot the variation of the friction factors (λ and λth) with the Re on a log-log scale. - Comment on your results. Do you know of any formulae for calculating the friction factor other than Equations (4.2) and (4.3)?

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No. 5 MEASUREMENT OF THERMAL CONDUCTIVITY OF A METAL Objective: In this experiment, the thermal conductivity K is determined , thermal conductivity of a metal is measured, and in addition, an overall heat transfer coefficient for three metals in series are calculated. Theory: In technical calculations it is important to determine the magnitude of a quantity of heat that is transferred per unit time between two media at different temperatures when the two media are separated by a wall. The transport of heat is termed heat transfer; it takes places primarily in three ways: - Thermal conduction in solid or moving liquid or gaseous bodies. - Convection between a solid and a flowing liquid or gaseous medium. - Thermal radiation, which occurs without a physical carrier. In the majority of cases heat is transferred by conduction, convection, and radiation. The different types of heat transfer are subject to different laws; they must therefore be addressed separately. In order to make accurate predictions of heat transfer rates through materials, it is necessary to first know the value of the thermal conductivity of the material itself. Thermal conductivity can be measured using standard methods, devices and techniques. If the heated and cooled surfaces are clamped tightly together and are in good thermal contact, then the two sections can be considered as a continuous homogenous sample of uniform cross section and material. The electrical power is given by: P= V. I W For the power absorbed by the water, the heat capacity of water Cp= 4180J/Kg.K yields a heat flow of:

According to Fourier's law of heat conduction: If a plan section of thickness x and constant area A, maintains a temperature difference transfer rate per unit time ̇ by conduction through the wall is found to be:

T then the heat

If the material of the wall is homogeneous and has a thermal conductivity K then:

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

The negative sign follows thermodynamic convention in the heat transfer is normally considered positive in the direction of temperature fall. However, for the purposes of the following illustrations the negative sign will be ignored. Apparatus: Figure 5.1 shows the component of the apparatus used in this experiment. The apparatus can be used to verify Fourier Law of conduction for linear and radial heat conduction cases.

Figure5.1: TheThermal Conductivity Apparatus

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Test procedure: In this section some experiments are described as examples of the experiments that can be performed with this unit. Depending on the skill, ambient temperatures, and the cooling water temperature and flow rate, variations may occur during experiments. Before an experimental series is recorded, consideration must be given to which specimens and material combinations are to be investigated. 1. Ensure that main switch is in the off position (the digital displays should not be illuminated). Ensure that the residual current circuit breaker on the rear panel is in the ON position. 2. Turn the voltage controller anti-clockwise to set the AC voltage to minimum. 3. Ensure the cold water supply and electrical supply turned on at the source. Open the water tap until the flow through the drain hose is approximately 1.5 liters/minute. The actual flow can be checked using a measuring vessel and stopwatch if required but this is not a critical parameter. The flow has to dissipate up to 65W only. Once the cooling water flow rate has been set, it only necessary to wait for a steady state operating condition to be established. It is then possible to start taking measurements. 4. Release the toggle clamp tensioning screw and clamps. Ensure that the faces of the exposed ends of the heated and cooled section are clean. Similarly, check the faces of the intermediate specimen (if in use) to be placed between the faces of the heated and cooled section. If instructed in the individual procedures for the experiment, coat the mating faces of the heated and cooled section and the intermediate section (if used) with thermal conduction paste. Ensure the intermediate section to be used is in the correct orientation than clamp the assembly tougher using the toggle clamps and tensioning screw. 5. Turn on the main switch and the digital displays should illuminate. Set the temperature selector switch to T1 to indicate the temperature of the heated end of the bar. Rotate the voltage controller to increase the voltage to that specified in the procedure for each experiment. 6. Observe the temperature T1. This should begin to increase. 7. Allow the system to reach stability, and take readings and make adjustment as instructed in the individual procedure for each experiment. 8. When the experimental procedure is completed, it is good practice to turn off the power to the heater by reducing the voltage to zero and allow the system a short time to cool before turning off the cooling water supply. 9. Ensure that the locally supplied water supply isolation valve to the unit is closed; Turn off the main switch and isolate the electrical supply. 10. Note that if the thermal conducting paste is left on the mating faces of the heated and cooled section for a long period it can be more difficult to remove than if removed immediately after completing an experiment. If left on the intermediate section it can attract dust and in particular grit which acts as a barrier to good thermal contact. Results: Plot the variation of temperature with distance from T1 for different voltage and calculate the thermal conductivity of aluminum specimen and compare that with published thermal conductivity values for aluminum.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Working Sheets:

Measuring Data:

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

SYMBOLS AND UNITS Symbol D A ∆X V I Q T ∆T K U R T

Units Diameter of element Heat transfer area Distance or thickness Voltage to heating element Current to heating element Power to heating element and heat transfer rate Temperature measured Temperature Difference Thermal conductivity Overall heat transfer coefficient Resistance to heat flow Elapsed time

Subscripts Hot Cold Int Hot face Cold face 1, 2, 3, 4…. 41

m m2 m V A W °C K W/mK W/m2K m2K/W seconds

Heating section Cooling section Intermediate section Contact face heated section Contact face cooling section Thermocouple positions Page

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No.6 NATURAL AND FORCED CONVECTION HEAT TRANSFER: FLAT PLATE AND FINNED PLATE Objective: In this experiment, natural convection for various geometries is studied. Learning Objectives / Experiments - free and forced convection heat transfer at different surfaces: * flat plate * pipe bundle *fins - temperature distribution in the heat exchanger - determination of the Reynolds and Nusselt numbers - calculation of heat transfer coefficient for free and forced convection - calculation of heat transfer rate and efficiency Theory : Convection is one of the three basic types of heat transfer. The heat transport is substance-bound. In the convection process, the whole fluid is moving. So-called fluid balls move (and thus transfer heat) from warm zones into cold zones. The different temperatures lead to density differences in the fluid so that a flow develops. In the case of free convection, the density differences result in a rather slow flow of the fluid with a more intensive heat transfer. In the case of forced convection, the flow is generated by a fan or pump. In this case, the heat transfer to fluid particles is lower, but more heat is transported than with free convection due to the much larger mass flow. The core element of the WL 352 experimental unit is a vertical duct into which a heating element is inserted. Air flows past the heating element and absorbs heat in the process. Three heating elements with different surfaces are available: a flat plate, a tube bundle or fins. For experiments on forced convection, an additional fan has to be activated. Sensors record the flow velocity of the air, the heating power and the temperatures at all relevant points. The measured values can be read on digital displays. At the same time, the measured values can also be transmitted directly to a PC via USB. The data acquisition software is included. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments. Heat transfer by natural convection occurs in many situations, and so it is important to understand it and be able to successfully model it. Consider a heated flat plate oriented vertically and transferring heat by only one of its surfaces to the surrounding air. Air near the plate becomes warm and its density decreases. Buoyant forces within the air act to move this less dense air upward, and it is replaced with cooler air. The motion of the air is due to the presence of the heated plate, and so we call this a natural convection problem. The convection equation for heat transfer from a flat plate to surrounding air is:

q=hc A(T4- T1 ) 42

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Where A; is the area of the plate in contact with the air. Using this equation and the data obtained by measurement for q, A, T4 and T1, the value for the convection coefficient, hc, can be determined. With the convection coefficient known, a dimensionless representation of the results can be made. A dimensionless graph could apply to any flat plate, not just to the one of this experiment. The dimensionless ratios of significance for this experiment are the Nusselt number Nu, the Rayleigh number Ra and the Prandtl number Pr:

hc L k g T4  T1 L3 Ra    Pr   Nu 

(6.2) (6.3) (6.4)

Where, L = plate length in vertical direction k = thermal conductivity of air g = gravitational acceleration β = 1/T1 = coefficient of thermal expansion α= thermal diffusivity of air = k/ρc ν= kinematic viscosity of air In steady operating mode, flow passes through the trainer with a constant air mass flow rate. The observation of the heat flow with the measured air mass flow rate is: (6.5) Where cp is the specific thermal capacity= 1.008 KJ/ Kg.K and ΔT is the temperature difference (T2 – T1), T1 is air inlet temperature and T2 is the air outlet temperature. The air mass flow rate ̇ consists of: (6.6)

(6.7) Where w is flow velocity m/s, Am is the area of duct m2= 0.0144 m2 and ρ is the density of air at inlet temperature. The value of R for dry air is 287 KJ/Kg.K and p is the atmospheric pressure. Another method for calculating the transferred α heat is via the heat transfer coefficient: (6.8) The area A α is the surface of the heat exchanger (flat plate) = 0.014 m2 and ΔT the temperature difference between the surface temperature T4 of the heat exchanger and the temperature of the fluid, in this case equal to the ambient temperature which is nearly equal to T1. 43

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2015 Spring Semester

The heat transfer coefficient can be determined experimentally using Formula (6.5) and Formula (6.8): (2.9)

Apparatus: Figure 6.1 shows the apparatus used in this experiment and its main components. Figure 6.2 is a sketch of the apparatus which consists of a rectangular duct that is held in the vertical direction. Flow straighteners are at the bottom of the duct, and an electrically operated fan is located at the top. Air flow is upward through the system. In this experiment, the fan is switched off. Along the front of the duct is a viewing window made of clear plastic. Behind the viewing window is an opening into which a heated model can be placed, as indicated in Figure 2.2. The apparatus is instrumented with thermocouples at selected locations. There is a thermocouple located upstream of the viewing window, and one placed within the heated model that gives a reading of the surface temperature. There is also provision for measuring the air velocity within the duct.

FIGURE 6.1: The apparatus for theheat convection experiment. 1 temperature sensor, 2 air duct, 3 thermocouple type K, 4 display and control unit, 5 "flat plate" heating element, 6 "finned" heating element, 7 flow sensor, 8 "pipe bundle" heating element, 9 measuring glands for thermocouple

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

FIGURE 6.2. A sketch of the apparatus for the heat convention experiment

General Procedure: 1. Place the flat plate heat exchanger into the duct. 2. Record the ambient air temperature (T1). 3. Set the heater power control to 75 W. 4. Allow the temperature to rise to 80 oC, and then adjust the heater power control to 20 W until a steady reading is obtained. 5. Record heated plate temperature (T4). 6. Set the fan speed control to give 1 m/s using the thermal anemometer. 7. Repeat this procedure at 1.5 and 2 m/s for the flat plate. 8. Replace the flat plate with the finned and pinned plates and repeat the procedure for each of them.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Free or Natural Convection In this experiment, the heated model is a flat plate. When installed, the flat plate is heated by an internal resistance heater, and the energy to the heater is controlled by a rheostat. The back and sides surrounding the heated flat plate are well insulated so that all energy from the rheostat is transferred to the air by the front face of the plate. Other models that could be used are a finned plate, a pipe-bundle, or a plate that has pin fins attached. Insert the flat plate model into the duct and turn the rheostat to a wattage of 5 W. (Note that if the plate temperature exceeds 100°C, a safety switch will turn the heater off.) Allow the system to reach steady state. Take readings of ambient temperature T∞, and plate surface temperature Tw. Repeat this procedure for wattages of 2, 4, and 6 W (Table 6.1a). Measure the physical dimensions of the flat plate.

q (W)

T1

Table 6.1a. Measurements T4 hc Ra

Nu

Pr

Forced Convection Insert the flat plate model into the duct and turn the rheostat to a preselected wattage, say 10 W. (Note that if the plate temperature exceeds 100°C, a safety switch will turn the heater off.) Turn the fan on and use the controller to get an air velocity of 0.5 m/s. Allow the system to reach steady state. Take readings of ambient temperature T1, and plate surface temperature T4. Repeat this procedure for air velocities of 1.0, and 1.5 m/s. Measure the physical dimensions of the flat plate. Next, change the wattage of the heater to another value, and repeat the experiment for air velocities of 0.5, 1.0, and 1.5 m/s. Repeat the experiment again for a third heater wattage.

 (m/s)

T1

Table(6.1b) Measurements T4 hc Re

Nu

Pr

Free convection Results Construct a graph of power (vertical axis) as a function of temperature difference, T4- T1. Using Equation (6.1a) and the data obtained from the experiment, determine an average value for the convection coefficient, hc. Using the data obtained in this experiment, calculate Nusselt number Nu, Rayleigh number Ra and Prandtl number Pr. Graph Nusselt number (vertical axis) versus Rayleigh number using the data. 46

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Other Geometries This experiment can be repeated with a flat plate that has longitudinal fins attached, as shown in Figure 6.1 and Figure 6.2, or with a pipe bundle. Perform this experiment for the heated model assigned to you by the laboratory instructor. Forced Convection Results Construct a graph of velocity (vertical axis) as a function of temperature difference, T4 – T1, and label each line according to the wattage selected. Table 6.1b Using the data obtained in this experiment, calculate Nusselt number Nu, Reynolds number Re and Prandtl number Pr. Graph Nusselt number (vertical axis) versus Reynolds number. Other Geometries This experiment can be repeated with a flat plate that has longitudinal fins attached to it, a pipe bundle, or with a flat plate that has pin fins attached. Perform this experiment for the heated model assigned to you by the laboratory instructor. Discussion Discuss your results and observations and give your comments in the conclusion. Plot graphs of velocity against temperature difference(T4 –T1)

For each of the

plates. Fit a straight line through the points of each plate.

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2015 Spring Semester

Physical Properties of air

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2015 Spring Semester

List of formula symbols and units used

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2015 Spring Semester

Experiment No. 7 Heat Exchangers Objective: Learning Objectives / Experiments In conjunction with a heat exchanger (WL 110.01 to WL 110.04) - plotting temperature curves - determining the mean heat transfer coefficient - comparing different heat exchanger types

Theory: Heat exchangers transfer thermal energy from the flow of one medium to another. The two flows do not come into direct contact with one another. Efficient heat transfer is a prerequisite for economical processes. Therefore, different heat exchanger types are used in practice depending on the requirements. This experimental unit can be used to investigate and compare different heat exchanger designs. The complete experimental setup consists of two main elements: WL 110 as service and control unit and choice of heat exchanger: Tubular heat exchanger (WL 110.01), plate heat exchanger (WL 110.02), shell and tube heat exchanger (WL 110.03) and jacketed vessel with stirrer and coil (WL 110.04). Water is used as the medium. The heat exchanger to be investigated is connected to the service unit. The hot water flows through the heat exchanger. Part of the thermal energy of the hot water is transferred to the cold water. Reversing the water connections changes the direction of flow and thus allows parallel flow or counter flow operation. The main function of the WL 110 is to provide the required cold and hot water circuits. To do this, the service unit is equipped with a heated tank and pump for the hot water circuit, connections for the cold water circuit and a switch cabinet with displays and controls. A temperature controller controls the hot water temperature. The flow in the hot water and cold water circuit is adjusted using valves. The cold water circuit can be fed from the laboratory mains or the WL 110.20. The measured values can be read on digital displays. At the same time, the measured values can also be transmitted directly to a PC via USB. The data acquisition software is included. In experiments, the typical characteristic value determined is the mean heat transfer coefficients. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments. Power Emitted = Power Absorbed = Power Lost = Power Emitted - Power Absorbed Efficiency =

x 100

Log mean temperature difference

=

Over all heat transfer coefficient U = Initial values of variables to be used: 50

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Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Controlled hot water temperature= Controlled cold water temperature= Hot water flow rate =2000 cc/min Cold water flow rate =1000 cc/min Reading to be taken:

Readings

Note the hot and cold water temperatures at inlet, mid-point and outlet once conditions have stabilized.

Power absorbed(W)

Power lost(W)

Efficiency

U (w/

Calculations

Power emitted(W)

It will be necessary to refer to standard tables for values of density and specific heat (Cp). Utilize appropriate conversion factors to ensure consistency of units when making calculations.

Apparatus:

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Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Fig.7.1: WL 110 Heat Exchanger The heat exchangers are supplied with the required flow rates of cold water and hot water by the WL 110 Service Unit. The service unit can be combined with the following heat exchangers: • WL 110.01 Tubular Heat Exchanger • WL 110.02 Plate Heat Exchanger • WL 110.03 Shell and Tube Heat Exchanger • WL 110.04 Jacketed Vessel with Stirrer and Coil Together, the service unit and a connected heat exchanger make up a complete experimental setup. In the heat exchanger, thermal energy is transferred from the hot water to the cold water. This thermal energy is added in the service unit by heating the hot water. These experiment instructions provide a detailed description of the service unit and the four heat exchangers mentioned above. The WL 110 series is supplemented by the WL 110.20 Water Chiller. The WL 110.20 allows operation at high ambient and water temperatures.

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Chemical Engineering Lab 1 Manual – CAS Sohar

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2015 Spring Semester

Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Unit description and function The key function of the service unit is to provide the required cold and hot water flow rates for the connected heat exchanger. In the heat exchanger, thermal energy is transferred from the hot water to the cold water. The thermal energy transferred to the cold water is added in the service unit by heating the cooled hot water. In addition, the service unit displays the measured values and transfers them to a PC.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Fig 7.2.: The service unit with the WL 110.01 Tubular Heat Exchanger connected.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Fig. 7.3: Control and display panel

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

WL 110.01

WL 110.02

Fig.7.4: Tubular and Plate Heat Exchanger (WL 110.01 and WL 110.02)

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

WL 110.03, tube bundle

WL 110.03 WL 110.04 Fig.7.5: Shell and Tube Heat Exchanger and jacketed Vessel with Stirrer and Coil (WL 110.03 and WL 110.04)

Results: - Plotting temperature curves - Determining the mean heat transfer coefficient - Comparing different heat exchanger types

Other Geometries : This experiment can be repeated with different types of heat exchangers.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No.8 Temperature Measurement Bench

Objective: The aim of this experiment is to get familiarized with a number of different methods of measuring temperature. Highlighting accuracy and sensitivity of each in a variety of working conditions, and to compare the characteristic responses and accuracy of the measurement techniques incorporated on the bench. Theory: The measurement of temperature is of crucial importance in monitoring the performance and correct functioning of variety of equipment and process involved. There are numbers of different methods of measuring temperature by using such as Mercury in glass thermometer, Vapour pressure thermometer, Thermocouple thermometer and Thermistor thermometer. All of these instruments are differ in the way of work and in the way of use. Some of these can be read the temperature directly and some of them need pivoting. Also these instruments have different operating ranges. Figures (1.1) shows the layout of the unit and figure (1.2) shows the other component of the base unit. . Apparatus: The apparatus layout used to measure the temperature is shown in figure 8.1 and 8.2. It consists of the following: -Water Heater. -Mercury-in-glass Thermometer. -Vapour Pressure Thermometer. -Thermocouple Thermometer. -Thermistor Thermometer.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Figure 8.1: Apparatus of Temperature measurement Bench WL 202 base unit

Figure 8.2: Other component of WL 202 base unit 60

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Procedure: Use of a Vapour thermometer with Mercury-in-glass thermometer -

Fill the water heater with pure water. Place the heater in its retaining bracket and connect the power cord. Place the platen on the support bracket above the water heater. Remove the Vapour pressure thermometer from the storage case and insert the stem into the hole provided in the platen. Partially unscrew the top of the gland fitted to the platen and moisten the O-ring within the gland. Remove the Mercury-in-glass thermometer from its storage case on the backboard. Carefully insert the bulb of the thermometer in to gland, ensuring the gland to retain the thermometer. Operate the rocker switch adjacent to the power regulator and turn the regulator clockwise half way through (say to number 7).

As the temperature of the water rises note down the readings of both the vapor pressure and mercury-in-glass thermometers, filling the following table. Results and Calculations: Use of Vapour pressure, Thermocouple and Thermistor thermometers results to be compared with Mercuryin- glass thermometer. The vapour pressure, thermocouple and thermistor thermometers installed on the bench are calibrated to provide a reasonably accurate temperature. The output of the thermocouple is 1mV/1°C. The thermistor thermometer is calibrated to provide a temperature resolution of 0.1°C over the range 0 to +100°C. Mercury-in-glass thermometer [°C] 30 40 50 60 70 80 90 100

Vapour pressure The thermistor The thermocouple thermometer [°C] thermometer [°C] thermometer [°C]

Required -

Compare mercury-in- glass thermometer (°C) vs. the others thermometers in terms of accuracy and sensitivity. Show the comparison above on graph. Submit your report including any pertinent remarks of discussion and conclusion. 61

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Experiment No.9 Marcet Boiler

Objective: The aim of this experiment is to investigate the relationship between pressure and temperature of a saturated steam. Purpose: This experimental unit demonstrates the relationship between pressure and temperature of saturated steam. The saturation pressure curve can be determined up to a pressure of 15bar. A defined amount of water is heated in a pressure vessel using an electric heater. The temperature and pressure can be tracked continuously on a digital temperature display and a Bourdon tube manometer. A pressure relief valve and a high temperature cut-out are fitted as safety devices. Experiments with hot steam should only be performed under the supervision of trained personnel.

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Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Theory: While water boils in an open vessel at a temperature of 100 oC, it does not turn to steam in an enclosed vessel, such as steam boiler, until a higher temperature. The heat initially causes water molecules to evaporate. This causes the pressure in the steam chamber, and thus in the water, to rise. As the steam pressure rises the boiling point temperature also increases, because the water molecules encounter increased resistance as they attempt to move from liquid to gas form. Consequently, each steam pressure has an accompanying precisely defined boiling point temperature. . Apparatus/Unit Description: The main element of the WL 204 unit (see Fig9.1) is the stainless steel steam boiler (7). It has a mineral wool insulating jacket. The filler opening (6) is used to pour water into the boiler. The overflow valve (3) closed off by means of a hand wheel, is used to ensure the vessel is filled to the correct level. The drain valve (1) can be used to drain the vessel. An electrical heater (2) is bolted to the floor of the boiler in such a way that the heating filament protrudes from below into the boiler. A manometer (8) is fitted in the lid of the boiler to provide a direct indication of the boiler pressure. There is also a temperature sensor (4) to measure the boiler temperature, and a safety valve (5) to prevent excess pressure build-up in the boiler. The boiler temperature can be read from the digital display (11) fitted into the switch cupboard. The unit is switched on at the master switch (9). The additional heater switch (10) can be used to switch the heater on and off as required during the experiment.

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Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Figure (9.1) Unit WL 204 layout (Marcet Boiler) Procedure: The boiler need only be filled once before the unit is run for the first time. The level should subsequently be routinely checked at regular intervals after a certain number of experiments have been performed. - Place the bench top unit on a flat surface. - Fit the enclosed section of tubing to the overflow and open the valve (3). - Fill the enclosed section of tubing to the drain (1) and close the valve. - Remove the plug from the filler opening (6) and pour water into the boiler until it emerges at the overflow. - Close the off the filler opening again with the plug. - Connect the unit to the main electricity supply. - Switch on the unit at the master switch (9). - Press the heater switch (10) to start the experiment. - Heat up the boiler to 100 oC. let the water cook approx. 1 min, so the steam can pass through the open valve (3) - Close off the valve (3) again. Log the boiler pressure and temperature values in table (9.1). After the experiment switch off the unit at the master switch and leave the boiler to cool down. 64

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Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

Results: - Compare you own measurement with the values from the literature. - Plot the graph of temperature against pressure experimentally and theoretically.

Conclusions: - Explain why it was first necessary to expel the air from the apparatus. - Point out any possible of error

Working Sheet: Table(9.1) Measurement Recording Pressure, relative [bar] 0.5 1 1.5 2 2.5 3 4 5 6 7 8 9 10 11 12 13 14 15

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Pressure, Absolute [bar]

Steam temperature [oC]

Temperature in oC According to literature 111.37 120.23 127.43 133.54 138.87 143.62 151.84 158.84 164.96 170.41 175.36 179.88 184.07 187.96 191.61 195.04 198.29 201.37

Prepared by-Dr Hind Barghash

Chemical Engineering Lab 1 Manual – CAS Sohar

2015 Spring Semester

References: C. T. Crowe, D. F. Elger, B. C. Wiliams, and J. A. Roberson, Engineering Fluid Mechanics, 9th edition, 2009. (ISBN: 978-0470409435) Experimental Manual, Fluid Mechanics, College of Engineering, Chemical and Petroleum Engineering/ Mechanical and Industrial Engineering Department, Sultan Qaboos University. Paul F. Ruff, Julia C. Muccino, Scot L. Thompson, CEE 341 Fluid Mechanics for Civil Engineers Lab Manual. G.U.N.T., Experiments Instructions Manuals

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