World Transactions on Engineering and Technology Education
2009 WIETE
Vol.7, No.1, 2009
Green engineering labs for a multidisciplinary freshman engineering course
Joshua R. Wyrick
Rowan University
Glassboro, New Jersey, United States of America
ABSTRACT: The emergence of sustainability and green engineering projects is re-shaping the engineering classroom.
One of the vehicles for these topics at Rowan University is within the Engineering Clinics- project-based, required
courses. The Clinics are designed to be fully integrated and multi-discipline. The laboratories used in this course
incorporate mechanistic elements from all four engineering disciplines offered at Rowan (electrical/computer,
civil/environmental, mechanical and chemical). The uniqueness of these labs is that all have the exact same objective –
to create a pulley and weight system powered by a renewable energy. The energy source is the variable, and thus the
crux of the labs. To operate the system for each lab, the students were tasked to create a: (a) solar panel array connected
to a motor, (b) hydro-powered turbine system, (c) wind-powered turbine system, and (d) chemical reaction battery
connected to a motor. All four engineering disciplines are covered, and all the labs (and hence energy sources) are
directly inter-comparable.
INTRODUCTION
As the world’s population and their needs expand every day, innovative engineers strive to minimise its effect on our
quality of life and modernise our technology in a more sustainable manner. Sustainable engineering, commonly referred
to as
green engineering
, has quickly become a critical societal issue, an issue that the engineers of today and tomorrow
will play a dramatic role in solving. Many universities are incorporating green engineering concepts into their core
curriculum. In fact, the Board of Directors for the American Society of Engineering Education (ASEE) considers it a
priority that all engineering programmes prepare their graduates for a profession that uses sustainable engineering
techniques and methods [1]. These techniques include alternative solutions to the consumption of non-renewable energy
sources, such as oil. As government administrations in the USA set such ambitious goals like doubling the production
of renewable energy within the next four years, today’s engineering graduates must be at the forefront of such
technology. Education that focuses directly on alternative energy solutions is vital to the future of the engineering
profession, and to the sustainable development of the world and its communities [2].
This article will introduce a series of experiments that focus on renewable energy sources that are designed to be
integrated into a multi-disciplinary engineering course. These experiments will provide the students with the vocabulary
and design skills in sustainability and green engineering topics and encourage them to think about the future
implications [3]. The following sections will discuss the classroom setting in which these experiments were designed,
provide the basic objectives of the labs, and detail the individual experiments.
ENGINEERING CLINICS AT ROWAN UNIVERSITY
All universities strive to develop graduates with strong analytical and critical thinking skills, who have an understanding
of the role of engineers in developing a sustainable global community. The engineering programme at Rowan
University uses a multidisciplinary project-based team learning approach in the form of Engineering Clinics [4]. The
Clinics are required project-based courses that students take every semester. The Clinics enable built-in flexibility in the
engineering curriculum to include important technical and societal topics. This approach has provided significant
opportunities for students to acquaint themselves with real-world engineering issues, such as sustainability. The eight-
semester Engineering Clinic sequence at Rowan covers basic engineering measurements and design through a senior
capstone research project (Table 1).
Freshman and Sophomore Clinics serve as an introduction to the rigors and opportunities of an engineering major. They
typically incorporate topical engineering scenarios and use simple engineering projects to strengthen students’
understanding of mathematics and science principles. Junior and Senior Clinics consist of projects, often sponsored by
industry or government, which represent the culmination of the Rowan Clinic experience. Students apply engineering
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principles learned in the classroom to solve industrially and socially relevant problems. They also can learn new
engineering technologies within the Clinic context. The excitement of working on such relevant and meaningful
projects, especially at the Freshman Clinic stage, is a driving force for sustaining a student’s interest through graduation
and into his or her career. Introducing the students to green engineering early will also stress its importance in design,
rather than devaluing it by tacking it on at the end of many senior-level courses [5]. The lab experiments described
herein were designed for the first semester of the Engineering Clinic sequence (Table 1).
Table 1: Overview of the technical topics covered in the eight-semester engineering clinic course sequence.
Year
Fall Engineering Clinic Themes
Spring Engineering Clinic Themes
Freshman
Engineering measurements
Competitive assessment
Sophomore
Multi-disciplinary design modules
Multi-disciplinary design project
Junior
Product development
Process development
Senior
Capstone design/research
Capstone design/research
LAB DEVELOPMENT
The series of labs described here focuses on renewable energy and sustainable engineering, but still achieve the
fundamental objectives for any engineering lab, as well as conform to the basic twelve principles of green engineering
[6][7]. Because the students that comprise the class come from four distinct engineering disciplines, the laboratories
themes were approached from an interdisciplinary viewpoint. The labs had to be observably comparable, and therefore
each had to have the same ultimate objective. The idea of comparing four different types of renewable energy drove the
development of these labs. The four types of renewable energy examined in this course are: solar energy, hydropower,
wind energy and chemical reaction energy. The ultimate objective of the lab is to use each of these renewable energies
to generate power output in a repeatable and measurable manner. Each energy source is used to raise a given mass to a
given height. The measurable power output can be calculated using the following sequence of equations derived from
any basic physics curriculum:
(1)
(2)
(3)
where, is the force created by the gravitational acceleration applied to a given mass , is the work done by
F
g
m W
applying the force over a distance , and is the power generated by the work in a given time . Thus the measured
F
d
P
t
output power can be increased by lifting more weight for a given time, or decreasing the time it takes to lift a given
weight.
Prior to each lab, the students are tasked to research individually the renewable energy source that will be examined and
tested. As a result, they enter the lab with some background knowledge of the subject. During the labs, each group is
given a packet of material to be tested and used as their power source. They collect data from their own setup, draw
conclusions about each energy source, and suggest recommendations for engineering applications. After each
experiment, each group is expected to submit a written lab report on their findings. It should be noted that the goal of
each experiment is not to produce the most power, but for the students to understand the relationship between the many
variables and power output.
SOLAR POWER EXPERIMENT
The power source for the solar energy lab is an array of photovoltaic (PV) cells. PV cells convert incoming solar light
directly into utile electricity. PV cells consist of a specially treated semi-conductor material that absorbs protons of light
and release electrons. The released electrons are then captured and converted to a flow, which creates an electric
current. The behaviour of this current can be predicted by Ohm’s Law (Equation 4), which states that the product of the
resistance (R) and the electric current (amperage, I) is equal to the electric potential (voltage, V) of the flow:
(4)
V= IR
The potential voltage available is additive for a PV array connected in series (i.e. one large continuous current loop),
while the electric current is increased for PV cells connected in parallel (i.e. several current loops working together).
For this experiment, the generated electric current is channelled through a DC motor, which is connected to a spinning
axle. The expected effect of more voltage applied to the motor is faster spinning speed, while more amperage increases
the applied torque. As the axle spins, a string that is connected to a weight wraps around it. This string is connected to
the weight via a pulley that is located at the given measured height. Thus the weight, distance, and time can be
measured, and the power output calculated using Equation (3).
13
The first task for the students is to understand how PV panels operate in series and in parallel array systems. Each group
is given several PV panels, a bundle of connector wires, a resistor board, and a multi-meter (for measuring voltage and
amperage). To assess the potential voltage and amperage for a given array, the students measure and record the output
volts and amperes for a given set of resistors. By repeating this for all possible combinations of the PV cells, the
students now have an idea of which design will produce what power for their motor.
During the experiment, the students must choose an array design, set up the motor and pulley system, and record the
voltage and amperage of their circuit as they power their motor with the PV cells. Students record the amount of weight
they lift, the distance the weight was lifted, and the time in which the weight was lifted that distance. These
measurements are used with Equation (3) to determine power output. Students can then vary the weights used, and the
PV array design.
HYDROPOWER EXPERIMENT
An elevated tank of water serves as the power source for the hydropower lab. The elevated storage of water contains
potential energy, which is converted to kinetic energy when it drains through a lower outlet. As the water flows down
through the pipe, its velocity, and therefore its momentum, increases. At the exit of the pipe, the water impacts on a
waterwheel, thus converting its momentum to the momentum of the wheel (i.e. converting kinetic energy to mechanical
energy). The exit velocity is a function of the elevation of the stored water (Equation 5):
u
H
(5)
u = C
�
(gH)
This is not a perfect equation because of frictional losses within the flow-path (represented by a loss coefficient, C), but
it provides easily measurable quantities for the first-year students. The power (P) derived from the momentum can be
determined from Equation (6):
(6)
P = wρQ(u−w)(1−cosβ)
where is the tangential velocity of the waterwheel created by the velocity of the water, is the density of the water,
w
u
ρ
Q
is the volumetric discharge of the water, and is the relative angle of the turbine blades to the water flow. The
β
waterwheel will spin, thus wrapping up a string that is connected to the weight via a pulley. The tangential velocity can
be measured with knowledge of the length of the string that was used, the time it took lift the weight (i.e. wrap the
string around the axle), and the diameter of the axle. The weight, distance, and time can be measured, and the power
output can be calculated using Equation (3) and compared with the turbine power calculated using Equation (6).
During the hydropower lab, the first task for the students is to understand how best to convert the flowing water’s
momentum into mechanical power. Each group is provided with a kit of pieces that can be snap-locked onto each other
to form a flow conduit. The students can choose the length of the conduit, the number of conduit branches, the diameter
of each exit nozzle, and the angle in which the flow impacts on the waterwheel. Each of these parameters has an effect
on the potential momentum that can be transferred to the waterwheel. Before the experiment, the students must
construct their waterwheel housing and flow conduit.
During the testing phase, the students connect their conduit to the outlet pipe of the elevated tank and their waterwheel
setup to the weight and pulley system. The students measure the weight, the distance it travelled, and the time in which
it travelled that distance. The students also measure the volume of water consumed for their power generation, which
can be incorporated into appropriate discussions of the positives and negatives of renewable energy.
WIND POWER EXPERIMENT
The power source for the wind energy lab is a wind turbine. As wind impacts the turbine blades, they spin a system of
gears that is connected to a string which is connected to the weight via a pulley system. The concepts of converting the
wind’s momentum to the wheel’s momentum are similar to the hydropower experiment. However, the fluid that is used
to provide the momentum, and the mechanism in which that fluid acquires its momentum are different. To distinguish
this experiment from the hydropower experiment further, the wind turbine blades are attached to an interchangeable
system of gears of varying diameters. Different gear ratios will provide different speeds and/or torque for the axle that is
attached to the weight.
During the wind energy lab, the first task for the students is to understand how different gear ratios can provide different
power outputs from the same power input. Each group is provided with a commercially-available wind turbine kit [8].
With this kit, many variations of wind turbines can be created. The variations include the number of blades to be
attached to the turbine and the number and ratio of gears that connect the blades to the rotating axle. The shapes of the
blades are fixed, but the students will have the opportunity to manipulate these shapes during their Sophomore Clinic
project [9]. Before the testing phase, the students are tasked to manipulate various gear ratios in order to determine
potential turning speed and torque for the axle. The students have some freedom in deciding the design of the turbine
14
frame and gears. During the experiment, the students test the lifting power of their turbine against the number of
attached blades and a varying gear ratio. The students must again record the weight, the distance, and time, and compare
these values to the number of blades and gear ratios used. The wind speed is also measured and used as a comparable
variable in their reports.
CHEMICAL REACTION EXPERIMENT
The power source for the chemical reaction lab is a student-created alkaline battery cell. A battery cell is comprised of
two electrodes, a cathode and an anode. The electrodes are submerged in an electrolyte solution, which forms
electrically charged ions. The positive ions (cations) will move towards the cathode, while the negative ions (anions)
will move towards the anode. The battery cell described herein uses a zinc bar (Zn) as the anode that is submerged in a
potassium hydroxide electrolyte solution. The cathode is a magnesium oxide powder (MgO ). The chemical reactions of
2
the battery cell used for this lab are shown as Equations (7) (anode) and (8) (cathode).
−
−
Zn (s) + 2OH (aq)
→ ZnO (s) + H
O (l) + 2e
(7)
2
−
−
2MgO (s) + H O (l) + 2e
→Mg
O (s) + 2OH (aq)
(8)
2
2
2
3
–
As electrons pass from the anode to the cathode, an electric current is produced. This current is collected via a copper
e
wire set in the cathode powder. The current is completed by attaching the motor to the copper wire and the zinc bar. A
flywheel is attached to the motor which spins and wraps up a string that is attached to the weight via a pulley.
During the chemical reaction lab, the first task for the students is to understand how chemical reactions can produce a
flow of electrons (and thus electricity). The students first create a
voltaic pile
, which consists of stacking alternating
plates of copper and zinc separated by thin layer of saline solution. The resulting reactions between the copper and zinc
produce a small current that is measurable with an ammeter. The students then set up their zinc-magnesium battery cell.
Once the battery is charged, it is connected to the small motor that is connected to the weight and pulley system.
Measurements include the weights, distances, and times. Students can experiment with multiple battery cells attached in
series or parallel. These batteries do eventually lose power, which can segue into further discussions of the positives and
negatives of such renewable energies.
CONCLUSIONS
All of these laboratories are simple to develop and implement, and they may be adapted and modified at the discretion
of the individual faculty. As described in this article, each lab requires one to two lab periods to complete. Each lab
centres on a particular renewable energy source, and caters to a specific engineering sub-discipline. A common
complaint among first and second year students about the Rowan Engineering Clinic programme is that even though the
classes are all multi-disciplinary, the assigned lab experiments are usually not multi-disciplinary. This stems from the
fact that the instructors typically assign projects that are within their realm of expertise. Several of the experiments
described are outside the expertise of the author, yet each lab was prepared and conducted with little difficulty. Because
each lab has a focus in each of the available engineering disciplines, each student will have the opportunity to run an
experiment that directly pertains to his/her major. At the same time, each student will be able to compare directly their
chosen major to the other disciplines.
Each of the experiments described herein may be a little rudimentary compared to how in-depth a lab on that subject
could be; however, they serve as a utile introduction for first-year students. This suite of labs accomplishes the main
goals of Freshman Clinic, or any introductory engineering course:
•
provide students with engineering experiments in which they will learn to accurately record measurements and
learn proper lab etiquette;
•
provide a multi-disciplinary class with comparable multi-disciplinary experiments;
•
provide experiments that have relevance to real-world engineering issues;
•
incorporate sustainable engineering topics into the curriculum while instilling a sense of global responsibility in
first-year engineers.
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ASEE, Board of Directors Statement on Sustainable Development Education (1999), 15 April 2009,
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Woodruff, P., Educating engineers to create a sustainable future.
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EPA/Academia collaboration.
Environmental Science and Technology
, 37,
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Sukumaran, B., Jahan, K., Dorland, D., Everett, J., Kadlowec, J., Gephardt, Z. and Chin, S., Engineering Clinics: an
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115-121 (2006).
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