Paper ID #21403

A Portable Engine Dynamometer Test Cell for Studying Spark-ignition En- gine Performance and Mechanical-Electrical-Thermodynamic Energy Con- version

Prof. Gene L. Harding, Purdue Polytechnic Institute

GENE L. HARDING is an associate professor of Electrical and Computer Engineering Technology at Purdue University, where he has taught since 2003. He has three years of industrial experience with Agilent Technologies, 28 years of combined active and reserve service in the United States Air Force, holds an MSEE from Rose-Hulman Institute of Technology, and is a licensed professional engineer. Dr. Megan Prygoski, Purdue University, West Lafayette

Dr. Prygoski teaches Mechanical Engineering Technology at Purdue University’s South Bend campus. She has her B.S. in Mechanical Engineering from the University of Arizona and a M.S. and Ph.D. in Mechanical Engineering from the University of Notre Dame. Her teaching focuses on energy transfer and thermodynamics and well as introductory mechanics classes such as Statics and Dynamics. Her personal interests are in Orthopedics which she uses as teaching examples in the mechanics classes. Dr. James Burns, Purdue Polytechnic Institute

Jim Burns, Ph.D. Assistant Professor, Department of Technology Leadership & Innovation Bio: Jim joined the faculty at Purdue Polytechnic in 2015 after completing a Ph.D. in Industrial Engineering from Western Michigan University, and has more than 10 years industry experience in the manufacturing sector in a variety of roles including process engineering, operations management, and technical sales. His area of expertise centers on applying OR/MS and Simulation techniques to Supply Chain & Operations Management problems, and has also conducted research in the areas of Human Factors and Work Design for evaluating time and motion efficiencies of operations. Jim also holds an undergraduate IE degree and a Six Sigma Greenbelt. Mr. Brian Jeffrey Carmichael, Security Automation Systems

Brian is a recent graduate of Purdue University’s Electrical Engineering Technology program. He lives and works in Indianapolis, Indiana. Matthew S. Engstrom, Purdue University

Matthew Engstrom is an undergraduate student at Purdue Polytechnic Institute working towards a Bach- elors degree in Electrical Engineering Technology.

c American Society for Engineering Education, 2018 A Portable Engine-Dynamometer Test Cell for Studying Spark- Ignition Engine Performance and Mechanical-Electrical- Thermodynamic Energy Conversion

Abstract

Automotive spark-ignition engines are great platforms for studying a variety of sensors, actuators, and control algorithms, but the size, expense, and maintenance required for an automotive engine coupled with a dynamometer test cell are impractical for many engineering and engineering technology programs. This paper proposes a portable engine-dynamometer test cell using a one-cylinder all-terrain vehicle (ATV) engine driving a set of high-current alternators. Engine loading is to be accomplished with a set of electric resistance heaters and a power switching array.

Although associated with a large university, this project is being undertaken by a satellite campus with limited space and financial resources. The plan is to implement the Engine-Dyno Project in phases over a period of years using primarily undergraduate students working on directed projects. The planned phases at this time are as follows: 1. Build a sturdy but portable cart to hold the engine, load cell, accessories, and controls. (This phase is complete.) 2. Install the engine and get it running with no load (complete). 3. Construct a thermoelectric loading system and test the engine using manual switching of the electrical load. 4. Implement and test an electronic control system to dynamically adjust loading. 5. Implement and test a dynamometer control and data acquisition system to perform automated test runs while recording data. 6. Convert the engine to electronic ignition and fuel injection and run baseline tests. 7. Design and implement an engine control system with user-programmable ignition and fuel system parameters, and appropriate test points for monitoring sensor data and controlling actuators. 8. Develop labs for the following courses: Introduction to Automotive Electronics, ECET 38501 (lecture) and ECET 38502 (lab), Heat and Power, MET 22000, and Applied Thermodynamics, MET 32000. The paper begins with background information about how the Engine-Dyno project came about along with a high-level description of the concept, requirements, and estimated timeline. It then lays out details for each project phase and the current project status, including photographs of the construction thus far.

Background

One of the authors teaches an introductory Electrical and Computer Engineering Technology (ECET) course in automotive electronics, ECET 38501 [1] and ECET 38502 [2], that focuses on sensors and actuators in the context of operating a spark ignition internal combustion engine. The course covers sensor characterization, actuator control, and circuit design to condition sensor output signals and drive actuators. It also describes control systems at a rudimentary level. During the course, students work with a variety of sensors and actuators: thermistor engine coolant and intake air temperature sensors, resistive gas pedal position and fuel level sensors, piezoelectric knock sensors, Wheatstone bridge intake air and oil pressure sensors, mass airflow sensors, inductive rotational sensors, fuel injectors, and distributorless ignition systems. Although these devices provide a great learning experience for interpreting sensor signals and driving fuel injectors and ignition systems, there is currently no opportunity to combine all of these devices with some control theory to operate a real engine.

Several years ago someone donated two single-cylinder gasoline engines to us. The lead author wanted to take advantage of the donations to create an engine-dynamometer test cell that would allow operation of one of these engines to do labs in his Automotive Electronics course, and possibly other courses. A traditional turnkey dynamometer is prohibitively expensive, so he decided to embark on a multi-year series of directed student projects (explained below) to create a dynamometer test cell that uses thermoelectric loading. The engine will drive a pair of heavy duty alternators that power an array of electric resistance heaters immersed in a tank of water. Power to the heaters, and thus load on the engine, will be regulated with power switching electronics using pulse width modulation (PWM) control. The long-term undertaking is called the Engine-Dyno project, and a system block diagram of the concept is shown in Figure 1.

Figure 1: Engine-Dyno system block diagram

A directed project, designated ECET 29900, is a variable-credit course that can be modified as needed to fit a wide variety of circumstances. For each project, the professor and student(s) craft a proposal that is essentially a contract for the project. It includes the stated purpose, general steps involved, deliverables, and the grading standard to be applied. A directed project template is shown at Appendix 1.

Once the Engine-Dyno is complete, the current plan is to continue a compressed version of the existing sensor/actuator labs for the Automotive Electronics course, but augment them with two or three labs that add engine control and data collection activities. Moreover, faculty in other departments plan to use the Engine-Dyno setup in two Mechanical Engineering Technology (MET) courses, two Industrial Engineering Technology (IET) courses, and a Statistics course.

The requirements driving the development of the Engine-Dyno test cell are listed below. Requirements followed by [old] are existing requirements that will be continued, while those followed by [new] are new requirements that cannot be met with existing equipment. 1. Condition and convert sensor signals into a usable form. One example would be implementing circuitry to convert the variable-frequency variable-magnitude sinusoidal signal from a magnetic wheel speed sensor and display revolutions per minute (RPM). [old] 2. Effect circuitry to drive automotive actuators, such as a fuel injector. [old] 3. Read sensor data from a running spark-ignition engine. Examples include crankshaft speed and position, exhaust gas oxygen levels, intake manifold pressure, and intake air temperature. [new] 4. Drive actuators, such as fuel injectors and spark plugs, on a running engine. [new] 5. Observe the effect on engine performance of changing fuel mixture and ignition timing. [new] 6. Experiment with different engine control algorithms and techniques. [new] 7. Calculate and experimentally measure energy conversion based on heat transfer and fuel consumption measurements. [new] 8. Any lab equipment emitting noxious fumes must be portable so it can operate outside due to a lack of proper ventilation inside the building. [old]

We are currently in Phase 3 of an 8-phase design process. The estimated timeline for the project is depicted in Table 1. This paper discusses the details regarding each project phase, some of which are completed, in progress, and not yet started. For the latter we list the learning objectives that will drive the student directed projects. Table 1: Estimated project timeline by phase

Phase # Description Status Planned Completion 1 Build cart Complete August 2016 2 Running engine Complete 05 December 2017 3 Thermoelectric loading via manual In progress Spring 2018 switching 4 Thermoelectric loading via PWM Not started Fall 2018 control 5 Data acquisition system Not started Summer 2019 6 Conversion to fuel injection and Not started Spring 2020 electronic ignition 7 Implement user-programmable Not started Fall 2020 ignition and fuel mixture maps 8 Develop labs Not started Summer 2021

Phase 1: Cart Construction

The labs in our building do not have the ability to vent engine exhaust to the outside, so the Engine-Dyno must be easily portable to the outside of the building before running the engine. It also must be strong enough to support the engine, alternators, pulley system, water tank, and associated controls and electronics. The cart is 25” wide by 37” long, making it small enough to easily fit through the doors to the lab, which have a 33” opening. (The external doors have a larger opening.)

The material of choice for the cart is 80/20, a system of T-slot aluminum box beams that is strong, versatile, and easily reconfigurable [3]. Neff Engineering did the design for us using dimensions we provided. The basic cart design is shown in Figure 2. The two beams across the top on the left side were added to the cart to support the engine. The plan was for the engine to sit atop those two beams, the two 250-A alternators to be suspended below the engine, the water tank to sit Figure 2: Photo of assembled cart

on the plate at the bottom of the cart, and the control electronics to be mounted at the top right side of the cart, as depicted in Figure 3.

The cart itself has been the single most expensive component of the Engine-Dyno project so far. Its bill of materials is shown in Appendix 2.

Phase 2: Running Engine

The second phase of the project was to get the engine running. The engine itself is an 8-hp Kawasaki TM FE250D, normally used in John Deere Gator all- terrain vehicles. Ours was donated, but an eBay listing [4] priced one at around $370. Although the Figure 3: Planned cart configuration engine was brand new, it was missing a number of components needed for it to be usable. These components included an air cleaner assembly, exhaust system, fuel tank, throttle and choke controls, battery, and electrical wiring.

The fuel tank was donated by a colleague at a different location from extra parts he had on hand. Two of the authors fabricated a custom bracket to attach the tank to the top of the engine so it provides fuel to the carburetor via gravity feed, as shown in Figure 4. The air cleaner assembly (right side of Figure 4) was attached directly to the carburetor. The throttle cable, choke cable, exhaust system, ignition switch, kill switch, and battery were purchased new. Two of the authors and our technician fabricated custom brackets for the throttle and choke cables, ignition and kill switches, and battery. The exhaust system was modified by cutting the stock exhaust pipe, mounting the muffler in a convenient location, and brazing a piece of corrugated stainless steel flex tubing to reconnect them. One of the student authors and the technician completed the electrical system wiring. After filling the engine with oil and the fuel tank with 87-octane gasoline, the engine was started. It fired right up right away and ran surprisingly quietly. Figure 4: Operational engine

The bill of materials for Phase 2 is Appendix 3. Phase 3: Thermoelectric Loading System

The third project phase will be manual implementation of the load. Key elements include alternators and a belt drive system to convert mechanical to electrical energy, heating elements to convert electrical to thermal energy, and a water tank to hold the water, which will absorb the thermal energy. The FE250D is rated at 8 hp, which is 5.97 kW, so the system was designed to provide a 6-kW load for a nominal 12-V output. Since normal alternator output in real systems is more like 13.5-14.5 V, designing for 12 V should provide capacity for more load than the engine’s peak output power, so that the engine can be successfully loaded at any point in its power curve.

A 6-kW load at a nominal voltage of 12 V would require 500 A of output current:

푃푙표푎푑 6푘푊 퐼푙표푎푑 = = = 500 퐴 (1) 퐼푙표푎푑 12푉

500-A alternators are very expensive, but an array of several alternators would require a complex belt drive mechanism. To strike a balance between cost and complexity, we chose to use a pair of 250-A alternators made by Power Strike to provide electrical power for the heating elements.

Although standard practice in the automotive industry is to use ribbed rubber belts to drive alternators, we chose to use a cogged belt system to provide a non-slip drive while allowing more margin in setting belt tension. An early mock-up of the setup is depicted in Figure 5.

An array of ten 60-W electric resistance heaters made by Denord will provide the electrical load and convert the electrical energy to thermal energy. They will be mounted to and suspended Figure 5: Mock-up of belt drive system from the lid of a 15-gal plastic tank made by Chem-Tainer, as shown in Figure 6.

While the fluid in the tank is contained, it is desirable to keep the temperature below 120°F in order to avoid scalding should a spill or splashing occur. For safety purposes, the goal is to keep the water in the tank below 95°F. Assuming a room temperature of 65°F and 12 gal of water in the tank, an input of 6 kW (20473 Btu/hr) of heat Figure 6: Electric resistance heater array could cause the water in the tank to rise to 95°F in under 9 minutes, as calculated below. At 65°F, the density of water, 휌, can be taken as 62.3 lbm/ft3, with a specific heat, c, of 1.00 Btu/lbm·°F. To calculate the time required to heat the water we must simply know the energy input from the Engine-Dyno, 퐸̇ , the volume of water, V, and the heat required to raise the temperature of water such that 푡 = 푄/퐸̇ , where the heat required to change the temperature can be taken as 푄 = 푚푐∆푇. Solving for the time yields:

푄 푚푐∆푇 휌푉푐∆푇 푡 = = = (2) 퐸̇ 퐸̇ 퐸̇

푙푏푚 푓푡3 퐵푡푢 (62.3 )(12 푔푎푙)(0.134 )(1.00 )(95℉ − 65℉) 푓푡3 푔푎푙 푙푏푚 ∙ ℉ 푡 = = 8.8 푚𝑖푛 (3) ℎ푟 (20473 퐵푡푢/ℎ푟)( ) 60 푚𝑖푛

We do not expect to ever need to run the engine at full power for such a long time. Most likely, it will run at full power for no more than several seconds at a time during engine performance measurements for the Automotive Electronics course, and at much lower power for several minutes at a time during experiments for the Heat/Power and Thermodynamics courses.

The loads will be switched manually in Phase 3, probably either using single-pole single-throw switches or, more likely, simply attaching the wires’ ring connectors by hand onto the terminal screws on the heating elements. The key goal at the end of Phase 3 is to demonstrate that the heating elements load the engine. This loading effect should be clearly indicated by an audible change in pitch of the engine when the heating elements are energized.

Also, the FE250D has its own magneto ignition system and simple battery charging system. The current plan is to keep the thermoelectric loading system electrically isolated from the engine’s built-in ignition and charging system.

Phase 4: Dynamically Variable Loading

There are two primary goals of Phase 4. The first is to be able to dynamically adjust the electrical load on the engine in very fine increments, much finer than turning one 60-W heating element on or off. The second is to enable that control via microcontroller.

Although the system has not been designed yet, the plan is to implement pulse width modulation (PWM) control with an array of high-current MOSFET (metal-oxide-semiconductor field effect transistor) switches. Switching frequency will be at least 50 kHz, which is high enough to prevent switching noise that is audible to humans and many animals. We have the capability to produce our own printed circuit boards (PCBs), but the thickest cladding we can use is 2-oz copper. The copper thickness, combined with MOSFET pin spacing, will limit the per-trace current handling capacity. We plan to do a fair amount of experimental testing to determine safe and reliable current limits, which will in turn dictate the total number of channels required to implement the PWM controller.

During initial testing a benchtop function generator will likely provide the PWM signal to directly control a single MOSFET’s gate voltage. Once safe current limits are determined, a MOSFET driver will be added to control gate voltage, a microcontroller will trigger the drivers, and the system will be scaled up to handle over 600 A.

We expect to use a directed project to accomplish most of the student work for this phase. Tentative learning objectives include:  Identify integrated circuit (IC) package options for the power switching devices;  Test current capacity on a printed circuit board (PCB);  Implement the power switching array;  Develop a digital control system to operate the switching array. This project could involve two students: one to develop the power switching array, and one to develop the controller.

Phase 5: Data Acquisition System

Phase 5 will implement a system to monitor performance of both the engine and the thermoelectric energy conversion apparatus. As the overall project progresses more sensors will likely be added, but the initial complement of sensors for the engine is expected to include: crankshaft position/speed and throttle position. Sensors to monitor energy conversion system parameters will probably include alternator output voltage and current, fuel consumption, tank water temperature, and perhaps tank water pump flow rate. The data acquisition system must be flexible to allow for additional sensor inputs in future phases. Moreover, the collected data may also be used to facilitate instruction for other courses, such as Elementary Statistics.

The alternators’ output voltage and current will allow computation of approximate engine output power. Combining that with engine speed will allow calculation of engine output torque, and thus generation of a traditional engine performance plot of torque and horsepower as a function of engine speed.

In Phase 5 the hope is to also implement electronic control of the throttle, perhaps with a stepper motor, and then employ computer control during each “dyno run” to autonomously generate a torque-horsepower curve. This data will be used as a baseline for performance comparisons when the engine is converted to electronic ignition and fuel injection.

It is expected that a directed project with multiple students will implement Phase 5. Tentative learning objectives include:  Physically install the sensors;  Implement signal conditioning circuitry to convert sensor signals to a format compatible with the data acquisition controller;  Create a digital controller with sufficient bandwidth and memory capacity to process and store acquired data.

Phase 6: Electronic Ignition and Fuel Injection

The principal goal of Phase 6 is computer control of the engine. The ignition will be converted from the stock magneto style to electronic ignition, and the carburetor replaced with a throttle body and fuel injection. Additional sensors, such as an exhaust gas oxygen (EGO) sensor and a knock sensor, will likely also be a part of the conversion. In spark ignition gasoline engines, the EGO provides feedback necessary to manage fuel mixture, and the knock sensor likewise provides data so the controller can optimize ignition timing. Other possible sensors include crankshaft and/or camshaft position sensors, and engine temperature sensor. The plan for this phase is to use a readily available aftermarket fuel injection conversion kit, then add other sensors as needed.

Directed project learning objectives for Phase 6 tentatively include:  Physically install the sensors;  Implement signal conditioning circuitry to convert sensor signals to a format compatible with the data acquisition controller;  Modify the data acquisition controller to accommodate the new sensor inputs;  Install the fuel injection conversion kit while maintaining operation of the acquisition system.

Once the engine is converted to electronic control, a new set of performance data will be taken. This data will be used for two purposes: 1) comparative analysis with respect to the carbureted configuration, and 2) a new performance baseline for use in Phases 7 and 8.

Phase 7: Programmable Ignition and Fuel Maps

Once electronic control has been implemented with the aftermarket kit, we plan to modify the system to allow user-programmable monitoring and control. If EGO, knock, crankshaft position, and camshaft position sensors were not added in Phase 6, some or all of them may be added in this phase. Test points and signal conditioning circuitry will be added to monitor the sensors using a custom microcontroller. Likewise, test points and driver circuitry will allow the microcontroller to trigger the ignition, manage the fuel injector timing and pulse width, and control any other necessary engine actuators.

The control algorithm will use tables to “map” base fuel injector pulse width and ignition timing to various engine conditions. The ability to customize and experiment with these fuel mixture and ignition timing maps will form the foundation for creating additional labs for the Automotive Electronics course.

If a directed project is used in this phase, learning objectives would probably include the following:  Generate baseline fuel and ignition timing maps based on the aftermarket controller and magneto-based ignition system;  Implement a microcontroller-based engine control unit to manage fuel injector timing and pulse width, and spark timing.

It should be noted that, since the magnitude of work in some of the phases is fairly large, it is also possible that some of them may be implemented as two-semester senior projects instead of one-semester directed projects.

Phase 8: Develop Labs

The Automotive Electronics course currently has labs that explore the following sensors: gas pedal, mass air flow (MAF), manifold air pressure (MAP), knock, oil pressure, crankshaft, anti- lock braking system (ABS) wheel speed, coolant temperature (CT), intake air temperature (IAT), and fuel level. Some of these labs will probably remain largely unchanged, while others will be modified or replaced to fit the Engine-Dyno setup.

At this time the plan is to leave the gas pedal sensor lab largely unchanged. This lab explores a variable resistance sensor with redundant voltage dividers to provide a safety margin. The Engine-Dyno is not expected to have an equivalent sensor, so use of the existing lab device will probably continue.

The fuel injection kit uses the speed-density method with IAT and MAP sensors to determine fuel injector pulse width. The IAT and MAP sensor labs will likely be modified to combine them into a single lab and add speed-density calculations. Also, custom probes will have to be fabricated to allow external monitoring of its signal(s). The MAF sensor lab activity will become a lower priority in the overall scheme of labs, so it may be retained or dropped depending on time available. Learning objectives for this lab, or labs, to be accomplished with a combination of pre-lab and in-lab activities are expected to be:  Characterize an intake air temperature (IAT) sensor;  Characterize a manifold air pressure (MAP) sensor;  Implement circuitry to interface each sensor’s output to a microcontroller;  Implement the speed-density calculation with a microcontroller and output estimated airflow.

The fuel injection kit does not include provisions for controlling spark timing. To do this electronically, the engine control unit (ECU) must have crankshaft and/or camshaft position and speed information. For closed loop ignition control, the ECU must also have knock sensor feedback. Our plan is to mount a reluctor wheel to the engine’s crankshaft, then use either a variable reluctance or Hall-effect sensor and signal conditioning to determine crankshaft speed and location. Although a camshaft sensor would be needed to determine whether the cylinder is in the compression or exhaust cycle, it is not important because the spark plug can be fired during the exhaust cycle without adverse effect. The current crankshaft and antilock braking system (ABS) sensor labs will likely be discontinued. The knock sensor issue will be more challenging. Our hope is to develop a custom knock sensor system of some sort to provide the needed signal. In order to do this, it may be necessary to engineer and install a cylinder-pressure monitoring sensor. Phase 8 could become two separate phases because of the complexity of this task. Once this system is developed, learning objectives are expected to include implementing signal conditioning for the crankshaft position and knock sensor signals, and possibly implementing spark timing control (probably with substantial scaffolding provided by the instructor).

The oil pressure sensor activity in the present course will also become a lower-priority task that may or may not be retained.

Since the FE250D is air-cooled, a CT sensor does not apply (no liquid coolant). Nevertheless, for closed-loop operation of gasoline powered spark ignition engines, engine temperature is an important determinant of fuel control mode [5]. To replace the current CT sensor lab activity, a different type of thermistor-based temperature sensor will be employed to provide this functionality. The goal is to characterize and understand the sensor operation.

The fuel level sensor is simply a potentiometer. Since this sort of signal conditioning is covered with multiple other sensors, this lab activity is a good candidate to be dropped.

The current Automotive Electronics course lab has no EGO sensor activities. The fuel injector kit contains a (presumably) narrowband EGO, so lab activities will be developed to characterize the sensor. This will also require developing a probe to acquire the signal.

The existing suite of lab activities includes three different actuators: fuel injectors, an ignition system, and an electric fuel pump. In the fuel pump lab, students analyze a failing fuel pump by examining its motor’s electric current waveform and comparing it to the waveform from a “good” pump motor. If there is room in the lab schedule, we expect to retain this lab activity.

The current fuel injector lab begins with design and implementation of a MOSFET driver circuit to drive a fuel injector, followed by an analysis of the waveforms to correlate physical actuation events to various waveform characteristics. Then, a standard aftermarket pulser is used to drive an injector supplied with pressurized water. The water is collected in a graduated cylinder; then the volume of water collected, the number of pulses, and the pulse width are used to calculate the fuel injector’s flow capacity. Finally, the injector’s spray pattern is photographed with the aid of a standard automotive ignition system timing light. We hope to continue some or all of these lab activities, but implement them using the model of fuel injector in the conversion kit.

The spark waveforms lab uses a real automotive ignition coil, plug wires, reluctance sensor trigger, spark plugs mounted in a custom fixture, and high- voltage current clamp to explore the waveforms and observe spark in a simulated automotive system. The fixture and current clamp are shown in Figure 7. The fixture allows the spark chamber to be pressurized to simulate the effect of combustion chamber pressure on spark activation. This lab activity is expected to be continued if there is time in the lab schedule. Figure 7: High-voltage plug wire probe The implementation of programmable fuel and spark timing maps in Phase 7 will enable some completely new labs. These labs will allow students to explore the impact of fuel mixture and spark timing on engine performance, effectiveness of various control algorithms, and experiments to compare different types of sensors.

From a thermodynamic standpoint, we hope to implement a number of labs and projects that can be used in Heat and Power, MET 22000, and Applied Thermodynamics, MET 32000. Heat and Power is a lab-based class in which students learn about heat transfer, conservation of energy, and are introduced to the idea of isentropic efficiency. In the second thermodynamic course, Applied Thermodynamics, there is no lab section, but class projects or demonstrations are useful to help students better understand system efficiencies, both maximum thermal and isentropic.

For Heat and Power three labs are proposed: a heat capacity lab, an energy analysis of an open system lab, and an efficiency lab. The heat capacity lab would correlate with the heat transfer portion of the course, while the other two would more closely tie into the thermodynamic portion of the course.

The heat capacity lab would allow students to calculate how long the engine can run before the temperature of the water in the tank exceeds unsafe levels, as discussed previously. The course currently has a lab that looks at conservation of mass in open systems, but we do not have the necessary sensors to do a complete conservation of energy for such systems. The use of the Engine-Dyno is proposed to replace the current conservation of mass lab. Using the water tank on the Engine-Dyno students will be able to calculate energy transferred from the engine’s mechanical output after its conversion to electrical then thermal form. Based on the input to the engine, an efficiency can be determined, which will be the purpose of the efficiency lab.

For Applied Thermodynamics, it is proposed that the students further investigate the efficiency of the engine and propose ways to design a more efficient engine. Using the thermoelectric loading system the students could gain a better understanding of how such loading affects the efficiency of engines. Using the engine, a research project is proposed for students to investigate this relationship. A portion of the project will be based on data collection to analyze the efficiency of the engine under different loads. Students can also calculate the amount of fuel used during operation, and based on the energy content of the fuel can calculate overall efficiency of the system.

In addition to Applied Thermodynamics, two other courses that will be able to make use of the engine are Elementary Statistics and Six Sigma Quality. Statistics is a required course for most engineering technology students, and Six Sigma is a popular elective for students in many programs. For the Elementary Statistics course, several foundational statistical concepts such as probability, descriptive and inferential statistics, hypothesis testing, and regression analysis can be applied to data collected from the engine. Students in the Six Sigma quality course will benefit by having the means to apply Design of Experiments (DoE) techniques and work through either pre-established or ad-hoc optimization problems relating to engine performance. A main reason the engine will be valuable is that experiments can be repeated from semester to semester, allowing learnings from previous semesters to be retained and compared to new data. Once the engine is fully functional, we have the potential to introduce basic DoE to students in their freshmen year through a real world application, furthering the benefit of the project.

It is anticipated that at least some planning for this kind of integration will take place during Phases 5, 6, 7, and 8 in order to ensure the data being captured are properly structured for these types of analyses. Most statistical analyses can be reduced to analyzing inputs and outputs in order to make decisions. Potential output variables of interest are engine horsepower and torque, spark timing, exhaust oxygen level, intake air temperature, manifold air pressure, and engine temperature. Potential input variables include throttle position, fuel consumption, crankshaft position, and engine speed.

Discussion

Several challenges must be overcome to implement this project. We are located at a satellite campus and hosted by another university, so our facilities are limited. Getting proper ventilation to run a gasoline engine inside the building was not practical. This drove the novel topology of using thermoelectric loading for the dynamometer portion of the test cell, making the entire test cell portable so it can be moved outside and run. This design approach also brings a multidisciplinary aspect to the project, which will eventually support courses in Electrical and Computer Engineering Technology, Mechanical Engineering Technology, and Industrial Engineering Technology. Involving so many disciplines is exciting and edifying to the faculty.

Another difficulty is a small student body, exacerbated by an enrollment slump in recent years that limits the pool of potential students to work on the project. The faculty hope was to have most, if not all, phases of the project implemented largely by students under the direction of faculty and the technician. Limited student availability some semesters, however, has hindered our ability to keep the project moving. On the other hand, our technician has taken an interest in the project, and we plan to make more use of his assistance in the future, especially, but not only, when student help is lacking.

Although limited funding is definitely a challenge, there happened to be a period early in the project when some funding came available. Responding quickly to this opportunity with a multidisciplinary proposal allowed us to secure funding to kick-start the project. On a related note, there is significant risk associated with a project that will extend over several years. Students will graduate, taking their project experience with them, and no longer be available to help. Faculty and/or staff could leave; if the cross-disciplinary benefits have not already been established at that point in time, those benefits could be lost. Nevertheless, limitations in funding, student help, and facilities virtually require such an approach for a project of this magnitude.

Despite the challenges, progress on the Engine-Dyno has been reasonable, and two students have invested many hours into it. In the process they have learned a number of valuable lessons. Interestingly, both students have been from ECET, and most of the lessons have been mechanical in nature, such as bracket fabrication and pulley selection. It could be argued that such cross- disciplinary lessons provide a strong enhancement to education in one’s own discipline. At this point, prospects look good to complete the project.

It is also important to look ahead to foresee significant capital expenses for the purpose of securing and expending funds when they are available. Furthermore, it is essential to carefully plan the tasks for each phase while being ready to adapt to changing conditions. Conversely, there is at least one potential downside. It is also possible to get distracted when looking ahead, losing focus on current project activities. This happened early on: We put funds and design energy into the alternator and pulley setup, the water tank, and the electric resistance heaters before getting the engine running. Although not a big deal, it delayed the emotional gratification of completing Phase 2 and hearing the engine run for the first time. Sometimes achieving those emotional milestones can help maintain everyone’s energy on such big projects. For instance, at the end of Phase 3 it will be very gratifying to hear the engine “bog down” when the electric heaters are switched on because that will validate the entire approach of using thermoelectric loading.

In summary, many obstacles can be overcome for something like the Engine-Dyno project if faculty work together and are willing to exercise novel approaches to problems that arise. Careful consideration to limitations such as potential funding, space, and facilities is critical, but need not necessarily prevent success. Looking ahead and identifying significant capital needs is critical when funding is sporadic, so that funding can be justified and acquired when it comes available. And finally, making good use of both student and technician support is important to keeping the project moving.

Conclusion

This paper described a long-term project to build a portable engine-dynamometer apparatus for studying electronic sensors and actuators, controls, internal combustion engine operation, energy conversion, thermodynamics, and statistical data analysis. The donation of a brand new Kawasaki one-cylinder engine was the catalyst that inspired the Automotive Electronics instructor to conceive and launch the project.

In the first few years, as the Engine-Dyno is developed, it will be the basis for several directed student projects. Once complete it will be used to enhance several courses in ECET, MET, and IET, as well as a Statistics course. Moreover, with student involvement so far, it has already become a fun application to support student learning in the context of a real-world system.

[1] Purdue University, “ECET 38501 Introduction to Automotive Electronics Lecture,” 2016. [Online] Available: https://polytechnic.purdue.edu/courses/course?courseid=82530. Retrieved 27 December 2017. [2] Purdue University, “ECET 38502 Introduction to Automotive Electronics Lab,” 2016. [Online] Available: https://polytechnic.purdue.edu/courses/course?courseid=82531. Retrieved 27 December 2017. [3] 80/20® Inc., aluminum extrusion construction materials, 2017. [Online] Available: https://8020.net/. Retrieved 28 December 2017. [4] eBay, listing for 8-hp Kawasaki FE250D-AS10 engine, 2018. [Online] Available: https://www.ebay.com/itm/8hp-Kawasaki-Engine-Tapered-John-Deere-Generator-FE250D- AS10/130949681843?hash=item1e7d3592b3:g:hc0AAOSwp7FaZiI-, retrieved 03 February 2018. [5] W. B. Ribbens, Understanding Automotive Electronics: An Engineering Perspective, 7th Ed. Waltham, MA: Butterworth-Heinemann, 2013. Appendix 1: Directed Project Proposal Template.

Appendix 2: Cart Bill of Materials (Phase 1).

Appendix 3: Bill of Materials to Get Engine Running (Phase 2). Phase 2 - Operational Engine Part Name Part Number Manufacturer Vendor Quantity Unit Price Order Price Cable Stop Assortment 03336 Dorman Advance Auto Parts 2 $ 2.99 $ 5.98 Ignition Switch 73455DL Del City 1 $ 9.72 $ 9.72 Filter M113621 - Greenmark 1 $ 17.35 $ 17.35 Air Cleaner VGA10803 - Greenmark 1 $ 45.78 $ 45.78 Exhaust Pipe VGA10883 - Greenmark 1 $ 22.32 $ 22.32 Nut M149532 - Greenmark 2 $ 1.31 $ 2.62 Gasket M73271 - Greenmark 1 $ 2.40 $ 2.40 Muffler VGA10877 - Greenmark 1 $ 190.56 $ 190.56 Lock Washer 12M7065 - Greenmark 2 $ 0.44 $ 0.88 Hose M153963 - Greenmark 1 $ 14.41 $ 14.41 Restrictor M152768 - Greenmark 1 $ 3.96 $ 3.96 Clamp TY22470 - Greenmark 2 $ 1.22 $ 2.44 Pad M149935 - Greenmark 1 $ 1.96 $ 1.96 Throttle Cable 12218 C&C C&C 1 $ 15.98 $ 15.98 Kill Switch a12081700ux0127 Uxcell Amazon 1 $ 5.90 $ 5.90 Choke Cable 237 C&C C&C 1 $ 9.95 $ 9.95 12V/24Ah Battery YTX24HL-BS PowerStar Walmart 1 $ 61.97 $ 61.97 Totals $ 408.22 $ 414.18