Implementing Team Based Learning in Freshmen Engineering Courses

Team Based Learning (TBL) is a specific pedagogical tool that emphasizes collaborative learning. Oftentimes TBL is confused with group activities and other active learning strategies involving student teams. TBL is distinct because it follows a prescribed sequence of individual work and group work, and includes immediate feedback as well as peer evaluation. TBL is widely used in medical, pharmacy and nursing schools and the use of TBL in engineering education is growing. The advantages of using TBL in the class room include: (1) students are held accountable for individual (pre-class) and group (in-class) work. (2) The responsibility for learning shifts from the instructor to the students, promoting lifelong learning skills. (3) The majority of class time is used for team assignments that use the course content applied to large difficult problems. (4) The students are actively engaged during class time. Furthermore, TBL is suitable for courses having as little as 12 students, but is also used in courses having up to 400 students. Therefore, TBL is an ideal tool to be used in freshman engineering courses. Implementation of TBL in an Introduction to Engineering course at the University of Alaska Anchorage in the Fall of 2013 is in preparation. In spite of all the benefits of using TBL, a possible deterrent for faculty to adopt TBL is the time intensive development of TBL modules and the lack of available support to develop and improve classroom materials. It is the intent of the authors to form a national freshmen engineering TBL support group to facilitate the implementation of TBL in freshmen engineering courses

Workshop A - Implementing the Design Your Process of Becoming a World Class Engineering Student Project

Many students come into an engineering program lacking a strong commitment to stay in an engineering program and to graduate with an engineering degree. For students to accomplish the challenging goal of graduating in engineering requires a strong commitment, and behaviors and attitudes to follow through that commitment. To strengthen the commitment of the freshman engineering students an innovative project has been developed. The project challenges students to develop their process to become a World-Class Engineering Student . Having freshman engineering students design their individually tailored learning process as part of a semester long project in the setting of a student success focused introduction to engineering course or any freshman engineering course will have a significant impact on their academic success by improving the students’ confidence and motivation to succeed in engineering. This workshop will show participants how to implement the Design your Process to become a World-Class Engineering Student into their own introduction to engineering courses

Transient Refrigerant Migration and Oil Distribution of an R134a Automotive A/C System

Automotive fixed orifice tube (FOT) systems are especially prone to cycling losses due to their clutch cycling operation. Therefore, it is important to better understand the dynamics of the refrigerant and oil migration during transient events such as cycling and start-up. To measure the refrigerant mass and oil distribution of an automotive R134a FOT breadboard system, two ball valves around each component are added. By simultaneously closing the valves, the refrigerant and oil is trapped in different sections of the system and can be measured. The transient refrigerant migration during a stop-start transient as well as the refrigerant mass distribution as a function of system charge at steady state operation is presented. A transparent accumulator and transparent tubes at the inlet and outlet of the accumulator are used to visualize the flow of the refrigerant. High speed video snapshots are presented for the first seconds after the start-up. The oil distribution at steady state as a function of total refrigerant charge is presented. In addition, the entrainment ratio of the liquid refrigerant and oil mixture through the oil bleeding hole of the accumulator is determined

Evaluation of Transient Refrigerant Migration Modeling Approach on Automotive Air Conditioning Systems

Automotive air conditioning systems are subject to constantly changing operation conditions and steady state simulations are not sufficient to describe the actual performance. The refrigerant mass migration during transient events such as clutch-cycling or start-up bas a direct impact on the transient performance. It is therefore necessary to develop simulation tools which can accurately predict the migration of the rerrigerant mass. To this end a dynamic model of an automotive air conditioning system is presented in this paper using a switched modeling framework. Model validation against experimental results demonstrates that the developed modeling approach is able to describe the transient behaviors ofthe system, and also predict the refrigerant mass migration among system components during compressor shut-down and start-up (stop-start) cycLing operations. To further investigate the potential of the dynamic modeling tools, two simulation examples of evaluating the system performance are given in the paper: (i) impact of system component variations on the refrigerant mass migration; and (ii) control implementation for the system start-up performance improvement

Incorporating Active Learning into a Thermal System Publications Lecture

Many mechanical engineering departments offer a thermal system design (or similar) course for senior students. Some courses have a laboratory component, but many are a lecture only format. This paper demonstrates how active learning—through virtual labs, a semester long project, and in-class assignments—was incorporated into the lecture portion of a thermal system design course to enhance learning and provide the students a laboratory experience without a physical laboratory. These active learning ideas can also supplement the learning during lecture for those courses which have a designated laboratory time. Anecdotal evidence of the activities indicates that students were engaged and enjoyed the active learning activities. Student reflections show that students not only achieved individual learning outcomes—such as analyze thermal system components, design and optimize thermal systems, etc.—but they synthesized them into their project and performed an evaluation, demonstrating they achieved the highest domain in terms of cognitive learning

Student Industry Cooperation for the Development of Thermal System Design Teaching Laboratory Equipment

In higher education, hands-on undergraduate education using state-of-the-art laboratory equipment is important to meet the quality standards expected in the engineering profession. However, the development of modern engineering laboratories is not only time consuming, but also budget constraints can hamper the development of needed laboratories for instructional purposes as Bidana and Billo state: Development of state-of-the-art engineering laboratories is becoming an increasing problem in the University environment. Due to the greater variety and increased complexity of much state-of-the-art hardware and software, the cost and cycle time for development and startup of a modern engineering laboratory can be excessive. This, together with decreasing budgets for technician support experienced by many engineering departments, often hamper efforts to develop new laboratories for engineering instruction. The solution presented by Bidana and Billo, O\u27Connel et al., and Webster is to involve students in the designing and building of laboratory equipment. Bidana and Billo investigated the development and startup of an Automatic Data Collection laboratory, whereas O\u27Connel et al. investigated the development of experiments for a power electronics course. Bidana and Billo concluded that the use of students for laboratory startup was a win-win situation and students were able to gain valuable technical educational skills . O\u27Connell concluded that students can participate meaningfully in the course lab component of curriculum development and Webster argues that the student\u27s interest is heightened by the design aspects . Although there is agreement that undergraduate students can be involved successfully in creating laboratory equipment, the question remains if this can be done for the equipment needed for a thermal system design teaching laboratory which requires sophisticated equipment such as an air handling unit simulator, a refrigeration simulator, or an air duct simulator. This paper presents an innovative approach of cooperation between industry and students to build equipment for a thermal system design teaching laboratory at a four year institution. Instead of buying higher educational laboratory test stands from commercial sources, test stands were built by mechanical engineering undergraduate students—as their senior design project— under the guidance of a faculty member and in collaboration with local industry representatives. The complete process—from initial outreach to the industry to achieve successful buy-in, the cooperative projects management and successful completion of the projects—is described in detail. This process can be replicated at other institutions in order to build educational laboratory equipment in a short time frame—one academic year—and without any funding from the institution

Experimental and analytical investigation of refrigerant and lubricant migration

The off-cycle refrigerant mass migration has a direct influence on the on-cycle performance since compressor energy is necessary to redistribute the refrigerant mass. No studies, as of today, are available in the open literature which experimentally measured the lubricant migration within a refrigeration system during cycling or stop/start transients. Therefore, experimental procedures measuring the refrigerant and lubricant migration through the major components of a refrigeration system during stop/start transients were developed and implemented. Results identifying the underlying physics are presented. The refrigerant and lubricant migration of an R134a automotive A/C system-utilizing a fixed orifice tube, minichannel condenser, plate and fin evaporator, U-tube type accumulator and fixed displacement compressor-was measured across five sections divided by ball valves. Using the Quick-Closing Valve Technique (QCVT) combined with the Remove and Weigh Technique (RWT) using liquid nitrogen as the condensing agent resulted in a measurement uncertainty of 0.4 percent regarding the total refrigerant mass in the system. The determination of the lubricant mass distribution was achieved by employing three different techniques-Remove and Weigh, Mix and Sample, and Flushing. To employ the Mix and Sample Technique a device-called the Mix and Sample Device-was built. A method to separate the refrigerant and lubricant was developed with an accuracy-after separation-of 0.04 grams of refrigerant left in the lubricant. When applying the three techniques, the total amount of lubricant mass in the system was determined to within two percent. The combination of measurement results-infrared photography and high speed and real time videography-provide unprecedented insight into the mechanisms of refrigerant and lubricant migration during stop-start operation. During the compressor stop period, the primary refrigerant mass migration is caused by, and follows, the diminishing pressure difference across the expansion device. The secondary refrigerant migration is caused by a pressure gradient as a result of thermal nonequilibrium within the system and causes only vapor phase refrigerant migration. Lubricant migration is proportional to the refrigerant mass during the primary refrigerant mass migration. During the secondary refrigerant mass migration lubricant is not migrating. The start-up refrigerant mass migration is caused by an imbalance of the refrigerant mass flow rates across the compressor and expansion device. The higher compressor refrigerant mass flow rate was a result of the entrainment of foam into the U-tube of the accumulator. The lubricant mass migration during the start-up was not proportional to the refrigerant mass migration. The presence of water condensate on the evaporator affected the refrigerant mass migration during the compressor stop period. Caused by an evaporative cooling effect the evaporator held 56 percent of the total refrigerant mass in the system after three minutes of compressor stop time-compared to 25 percent when no water condensate was present on the evaporator coil. Foam entrainment led to a faster lubricant and refrigerant mass migration out of the accumulator than liquid entrainment through the hole at the bottom of the U-tube. The latter was observed for when water condensate was present on the evaporator coil because-as a result of the higher amount of refrigerant mass in the evaporator before start-up-the entrainment of foam into the U-tube of the accumulator ceased before the steady state refrigerant mass distribution was reached

Effect of Multiple Choice Testing on Student Performance in an Introductory Engineering Course

This study aims to compare student performance on introductory engineering statics material by comparing the exam scores of students who are given both multiple choice (MC) questions and constructed response (CR) questions to see whether the type of exam question makes a difference in student performance and understanding. Seventy-five students in an introductory engineering course did either a MC version or a CR version of each statics problem, resulting in MC answers and a control group of CR answers to each statics problem. The students were also polled for feedback regarding their preferences of test question format at the end of the semester. All the exams were graded by one professor, and the results showed little difference between the scores on the MC versus the CR versions of a question. The average score for the MC version was 80%, while the average score for the CR version was 76%. While MC questions may not be appropriate in all circumstances, the high performance on the MC questions, and similar performance on CR questions indicates that not only do students not guess at the answer, but also are able to show understanding of basic statics problems