CheLabWiki:Role of Advanced UG Engineering Labs

From CheLabWiki

…from CheLabWiki, an online resource for chemical-engineering laboratories located at www.chelabwiki.org; Site Revision #464; 6 October 2008.

In advanced engineering laboratory courses, students are expected to develop and exercise skills in experimental design, in experimental data analysis, and in multi-level communications. That's a lot to accomplish in one or even two courses.

The Engineer's Levels of Communication

The engineer is always the one in the middle. The engineer must talk “up” to management and marketing, and the conversations are dominated by economic terms, such as profit margins, man-hours, product distributions, market share, and return on investment. The engineer must talk “down” to operators and technicians, and those discussions are dominated by concrete measurables, such as flow rates, production schedules, maintenance protocols, and quality control. Further, the engineer must talk “sideways” to other engineers, scientists, computer programmers, and technical writers. In those interactions the talk is dominated by abstractions, such as energies, theoretical limits, probability distributions, and mathematical jargon. It takes years of study and practice to develop proficiency in all these levels of communication, and for most engineering students, an advanced engineering laboratory offers them their first chance to practice all three modes simultaneously.

The levels of communication help distinguish advanced engineering laboratories from other lab courses students have encountered. Additional distinctions arise from the ways that engineering enters laboratory activities; specifically, they arise from variants on the standard problem.

The Standard Engineering Problem

Figure 1: Schematic of the standard engineering problem in which a process converts input into output.

Much of engineering focuses on some aspect of the standard problem (see Figure 1): input is fed to a process, the process transforms the input in some way, and output is removed from the process. For example,

1. crude oil (input) is fed to a refinery (process), and gasoline (output) is removed;
2. coal (input) is fed to a power plant (process), and electrical energy (output) is removed;
3. numerical data (input) are fed to a computer program (process), and graphical information (output) is removed;
4. students (input) enter a curriculum (process) and leave as fledgling engineers (output).

The standard problem can be posed in either of two general forms: analysis or design. In an engineering analysis, we know the input and we know the process; the problem is to determine something about the output. For example, how much electrical energy can be obtained from a 200-ton hopper of coal fed to a 2,000 MW power plant operating at full capacity? In contrast, in an engineering design we know both input and output—the problem is to develop the process. For example, design a power plant that burns coal to produce 2,000 MW of electricity. Note that analysis differs from design only in the roles of knowns and unknowns, so any one standard problem might be posed as either analysis or design.

What's Special About Advanced Labs

In elementary lab courses, students usually perform analysis only. The experimental equipment and protocol (the process) are fixed, and students are expected to obtain experimental results (output) by providing certain input to the experiment. They then determine (by analysis) whether the measured output agrees with some theoretical expectation.

However, in advanced engineering laboratories, students engage in both analysis and design. In these situations students are asked to determine output (assess the performance of a pump), but to obtain the required result, they are given some latitude to vary aspects of the process (rpm of the motor that drives the pump) and its input (choice of fluids to be pumped). This is a problem of experimental design. They then perform an analysis to assess the validity of their result and make comparisons with theoretical predictions. This combination of analysis with design demands more time and effort from students than they usually devote to elementary lab courses.

The purpose of this website is to help students and instructors make good use of their time and efforts: to help teaching be more effective and learning more satisfying.