Introduction
The benchtop hybrid powertrain is a five-semester design/build/test project conducted by students in the Rowan University Mechanical Engineering program. Rowan University is a mid-sized comprehensive university in southern New Jersey, near Philadelphia. The Mechanical Engineering program is predominantly undergraduate, and many of its faculty members conduct research aimed at improving engineering education. Our goal in devising the benchtop hybrid powertrain project was to assess whether student knowledge retention is improved by having students conduct a long-term design project that draws on concepts learned in most of the core mechanical engineering courses including mechanical design, thermodynamics, fluid mechanics, machine design and system dynamics and controls.
Ensuring retention of engineering concepts can be quite challenging. Hearing a variation on 'but we never learned this!'' is an all-too-frequent experience for most instructors, and many students feel justified in jettisoning all knowledge of a subject once the final examination is past. The situation is well summarized by Avitabile[1]:
The unfortunate part is that as soon as the test is over or the course is completed, the students often just forget the material since they have no reason to retain the compartmentalized, modularized material.
Subjects that are separate in the curriculum, such as thermodynamics and mechanical design, are integrated in practice, since thermal and mechanical systems must function cohesively in real mechanical systems (e.g. an air conditioner). With this in mind, we developed a novel, potentially transformative approach to integrating coursework through five semesters of the core mechanical engineering curriculum. The work is designed to test two hypotheses:
- A long-term design project that integrates knowledge from multiple courses strengthens student knowledge retention.
- A large-scale design project requiring tools from many courses improves student problem-solving and design skills.
By integrating five semesters of the mechanical engineering curriculum into a cohesive whole, this project has the potential to transform the way undergraduate education is delivered. Before and after testing is being conducted to assess a) change in retention between courses and b) change in student problem-solving and design skills.
The Project
The primary components of the hybrid powertrain are as follows:
- The prime mover (in this case, an air-powered engine)
- Two electric motor/generators
- A planetary gearset
- A battery pack
- A control system for keeping everything running
Each of these components is designed and built as a module in a particular mechanical engineering course. The schedule for completing each module is given in the table below. Note that the dates in the table are given for the first cohort of students to complete the project; three more cohorts will work on the project so that a complete assessment can be conducted.
| Benchtop Hybrid Design/Build Schedule | |||
|---|---|---|---|
| Semester | Course | Module | |
| Year 1 (2011-2012) | Fall | ||
| Spring | ME Lab | Arduino-based tachometer | |
| Year 2 (2012-2013) | Fall | Thermal-Fluid Sciences I | Air-powered engine |
| Machine Design | Planetary gearset | ||
| Spring | Thermal-Fluid Sciences II | Air flow control module | |
| Year 3 (2013-2014) | Fall | System Dynamics and Control I | Electric motor speed control |
| Spring | System Dynamics and Control II | Overall control system | |
The modules are designed so that instructors at other institutions can adopt one or more, without having to implement the entire project at their institution. We acknowledge the difficulty of getting collaboration from multiple instructors across several courses - the Rowan team is special! However, it should be possible to try a subset of two or three modules at most universities. We are very interested in feedback on the modules; if you try one, please let us know!
Our Sponsor
This work has been very generously supported by the National Science Foundation's NSF-TUES (Transforming Undergraduate Education in Science, Technology, Engineering and Mathematics) program, under NSF-DUE #1044532. We are indeed grateful for their support!
Please note that any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
[1] Avitabile, P. 'And more again on the state of engineering education, Part 2 of 3 – Improvement' Journal of Sound and Vibration 39 (6) 5 (2005)
