ChE 381: Chemical Engineering Laboratory - I
and
ChE 382: Chemical Engineering Laboratory - II

How to Write a Good Unit Operation Laboratory Report

Chemical Engineering Department
University of Illinois at Chicago

The report for each experiment will depend on the experiment performed. Some of the experiments already come with a thorough instruction. Other experiments are open-ended with no instruction. For the first category of experiments the report will consist of the sections containing the Results, Discussion, and Conclusions. For the open-ended experiments a full report as described below will be required:

Sections in the Report

A full report will include the following sections.

Title

Abstract
Table of Contents
Introduction
Equipment and Procedure
Results and Discussion
Conclusions - sources of error/precautions
Appendix:
Raw Data as approved by the TA before leaving the lab
Hand-written sample Calculations. Also, a copy of the original data should be attached.

Audience

You should write your lab reports as if you were sending them to a busy supervisor who is relatively familiar with the project. Do not write the report as if it were merely a class assignment. You must think of the information which your supervisor needs in order to make a decision concerning your project, and then organize your report so that this information is first.

Deciding on the audience that you will write to is the most difficult task in technical writing. The material you select is obviously very different when presented to audiences which are: nontechnical, technical-but not in your field, and technical-but in your field. You should consider this very carefully when writing each section of your report. Simply ask yourself "What does my supervisor need to know?".

Abstract

The abstract is the most important section of any report. It should be designed for your intended audience so that they can decide whether it is relevant for them to spend their time reading or not. Therefore, the abstract usually should encapsulate the entire report including three parts: an objective, a brief statement of your results, and a brief statement of your overall conclusions. The objective should remind your boss of why the experiment was done because they are supervising many projects, and so can not remember the details of each project. Remember that your audience is a hypothetical supervisor. Therefore, do not write the objective as if you were writing the report to your professor. Do not say things like: "This experiment was done to learn more about blah blah blah." Instead, write something like: "The objective of this experiment was to determine the heat transfer coefficient for an agitated vessel for use in the design of similar heat transfer vessels."

The abstract should then contain a brief overview of your experimental results. It should not contain a list of all of your observations. Instead, you should include only a brief paragraph of a few sentences discussing what you found. For example: "The heat transfer coefficient for an agitated vessel was found at three agitator speeds." This is brief, and tells the reader that if they do not have to read this report if they are not interested in heat transfer coefficients.

The results are factual statements of what you did. You have not yet stated whether the experiment succeeded or not. You should now include a brief paragraph (or even a single sentence) stating your conclusions. Conclusions are your opinions concerning the facts based on your engineering judgement. For example, if your data did not satisfy the expected correlation, you should say so. Also, your conclusions should be directly related to your stated objective. If your objective was to test a given correlation, then your conclusion should state whether you were successful or not.

As a guide, the abstract should contain less than approximately 200 words for laboratory reports such as these. However, longer abstracts are appropriate if required to present an accurate overview of the project and shorter abstracts are appropriate if it meets the requirements stated above.

Introduction

It states the purpose of the investigation and provides the reader with enough background information so that he can understand the material in the report. For example, it may state that you measured the viscosity of various liquids using two types of viscometers. (Be careful not to duplicate information you intend to present in the experimental section.) You may want to briefly review how one obtains experimental values from the methods used. This section should be brief, since it is usually not necessary to provide extensive orientation to the reader of a laboratory report. This would not be the case, however, for a research project or thesis.

Equipment and Procedure

Briefly describe the experimental apparatus. Was it a wetted wall column, a capillary tube in a water bath, etc. This should be understandable by other engineers who are moderately familiar with the experiment. Only one or two paragraphs are necessary. In particular, you should not discuss details of the experiment which would be assumed by any engineer; remember that your audience is a supervisor who is also an engineer. For example, you should not write "The flow rate was changed by turning valve A". Instead, you might write: "Several cooling water flow rates were selected. Sufficient time was allowed for the system to reach steady state as indicated by the temperature." Present enough information so that your data in the results section can be easily understood. In particular, state any procedural methods you used that may influence your results.

These lab manuals are also available in the Computer Lab in CEB, so feel free to cut and paste any figures into your own report. However, your instructor does not simply want to reread the lab manual, so keep these details to a minimum.

Results and Discussion

First, be sure to perform all calculations in SI units. Much of your raw data will be taken in English units, as is still typical in industry. However, you should immediately convert your raw data directly to SI units in order to perform your calculations. Do not simply convert your final answer to SI.

Present the results of your calculations in an intelligible form. Do not simply put tables of data and graphs and expect your reader to know what you did. Include a discussion of your results in which you tell the reader what was done and provide an outline of all calculations that you make. Intermediate algebraic steps may be excluded (these should be presented in the Appendix instead), but it is important to list any assumptions that you make in the calculations or to assist the reader with any complex mathematical manipulations. This does not have to be lengthy, but it should be sufficient so that the reader can follow what was done. The body of the text can then refer to individual tables or graphs. These do not have to be on the same page as the text, but this is relatively easy to do on any word-processor, so you may want to learn how to cut and paste your tables and graphs from a spread-sheet software into a word-processor.

Be sure that your tables are well labelled. Do not use symbols without using words to explain the symbols.

Do not make your graphs or tables too large. It might be easier for the reader if several smaller graphs were on the same page so that relationships between the data can be examined.

Decide how much information should be on one graph. For example, do not make three separate graphs when you can draw three lines on one graph. This would allow trends to be noticed which would otherwise be overlooked. Conversely, do not put too much, or unrelated, data on a single graph. This can make the graph confusing.

Check these points in your write-up:

* Make sure there are enough words in the Results sections. You should not simply create tables and graphs without explaining them to your reader in words. A busy supervisor does not want to spend time figuring out what your headings mean, or that a table is summarizing the energy balance around an unspecified control volume. Therefore, follow the following format for your reports.

* Each table and figure must be numbered, and given a short descriptive title (Ex: Table 1: Energy balance for Condenser).

* Each table and figure must have one paragraph which describes the content of the table or figure in a few descriptive sentences. What information is the reader supposed to get out of the table? Remember to assume that your supervisor is reading this report. What information do they need?

* These tables, figures, and paragraphs should form a consistent narrative called the "Results". This means that the paragraphs should be put in a logical order so that one is linked to the other. Perhaps you would start with the material balances, and then the energy balances, etc.

* This sounds like a lot of work when creating a table or figure, and it is. However, you should spend time organizing your information before creating tables and figures in order to combine related information on one table or graph. Then, you will have less items to write about, and it will be easier for your reader to examine the relationships between your data.

Conclusions

Finally, present your conclusions. (Did the data match theory? Were any correlations derived? How do you explain any observed trends?, etc). This should expand slightly on the conclusions you presented in your abstract, but should still only be only one to two paragraphs. Again, be sure that your conclusions are related to your stated objectives, and relevant for your chosen audience.

Briefly state what conclusions can be drawn from the experiment. Some of these conclusions may simply be factual statements like: The efficiency increased as the agitator speed increased. However, you should also include some of your own opinions (for consideration by your supervisor) concerning the experiment. For example: The energy lost in the distillation column in heating the feed to a saturated liquid caused less methanol to be produced than indicated in the McCabe-Thiele analysis. Therefore, the feed should be preheated. This is a conclusion because you have decided (concluded) that one thing out of many potential causes produced a given effect.

(© 1998, Chem. Eng. Dep't, University of Illinois at Chicago, All Rights Reserved)

Last update: 8/31/98