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  1. Evaporative cooling, used in many industrial and residential applications, is a complex coupled heat and mass transfer process where fluid cooling occurs due to water vaporization and the conversion of sensible to latent heat. In this paper, the development, testing, and implementation of a small, highly visual, Low-Cost Desktop Learning Module (LCDLM) for demonstration of evaporative cooling phenomena in the undergraduate classroom will be presented. The newly developed cross-flow direct evaporative cooler module is constructed from inexpensive expanded aluminum packing media, an off-the-shelf, battery-powered computer fan, a simple water distribution system with a battery-powered pump, and clear acrylic housing. The LCDLM is operated in a non-steady-state recycle mode where a small volume of water is circulated and, depending on the water temperature, either heats or cools incoming air. Preliminary data for simple experiments that can be repeated in the classroom are presented showing the effect of varying the initial water temperature, water flow rate, and air velocity on the cooling rate and temperature profiles in the module. These variables can be easily controlled in the classroom so that students can quickly observe their effect on the performance of the evaporative cooler. Finally, we outline worksheet and conceptual assessment questions tomore »accompany classroom activities and present conceptual assessment results from a spring 2022 pilot classroom implementation of the evaporative cooler LCDLM in a Fluid Mechanics and Heat Transfer course. Significant student learning gains were observed after implementation, suggesting a positive influence of the LCDLM on understanding.« less
    Free, publicly-accessible full text available August 23, 2023
  2. In this paper we report on the development and testing of hands-on desktop learning modules for transport courses in the Chemical and Mechanical Engineering disciplines. Two modules were developed to demonstrate fluid mechanics-related concepts, while two other modules were created for energy transport in heat exchangers. These devices are small, inexpensive, and made of see-through polycarbonate plastics using injection molding. These desktop learning modules are particularly suitable for use in undergraduate classrooms in conjunction with lectures to illustrate the working mechanism of devices seen in an industrial setting. Experiments are performed to understand the flow behavior and heat transfer performance on these modules. Our results show an excellent agreement for hydraulic head loss, volumetric flow rates, and overall heat transfer coefficients between experimental data and the corresponding theory, justifying the design and use of these devices in the classroom. Furthermore, we have measured student learning gains through pre-and posttests for each module based on in-class implementations at different universities. Assessment of student learning outcomes shows significant improvement in conceptual understanding when these modules are used in the undergraduate class.
    Free, publicly-accessible full text available August 23, 2023
  3. Our team has developed Low-Cost Desktop Learning Modules (LCDLMS) as tools to study transport phenomena aimed at providing hands-on learning experiences. With an implementation design embedded in the community of inquiry framework, we disseminate units to professors across the country and train them on how to facilitate teacher presence in the classroom with the LC-DLMs. Professors are briefed on how create a homogenous learning environment for students based on best-practices using the LC-DLMs. By collecting student cognitive gain data using pre/posttests before and after students encounter the LC-DLMs, we aim to isolate the variable of the professor on the implementation with LC-DLMs. Because of the onset of COVID-19, we have modalities for both hands-on and virtual implementation data. An ANOVA whereby modality was grouped and professor effect was the independent variable had significance on the score difference in pre/posttest scores (p<0.0001) and on posttest score only (p=0.0004). When we divide out modality between hands-on and virtual, an ANOVA with an F- test using modality as the independent variable and professor effect as the nesting variable also show significance on the score difference between pre and posttests (p-value=0.0236 for hands- on, and p-value=0.0004 for virtual) and on the posttest score onlymore »(p-value=0.0314 for hands-on, and p-value<0.0001 for virtual). These results indicate that in all modalities professor had an effect on student cognitive gains with respect to differences in pre/posttest score and posttest score only. Future will focus on qualitative analysis of features of classrooms yield high cognitive gains in undergraduate engineering students.« less
    Free, publicly-accessible full text available August 23, 2023
  4. As this NSF LCDLM dissemination, development, and assessment project matures going into our fourth year of support we are moving forward in parallel on several fronts. We are developing and testing an injection-molded shell-and-tube heat exchanger for heat transfer concepts, an evaporative cooler to expand to another industrial-based heat exchange system, and a bead separation module to demonstrate principles of fluid mechanics in blood cell separations applications. We are also comparing experimental data for our miniaturized hydraulic loss and venturi meter LCDLMs to predicted values based on standard industrial correlations. As we develop these new learning components, we are assessing differential gains based on gender and ethnicity, as well as how students learn with existing LCDLMs in a virtual mode with online videos compared to an in-person hands-on mode of instruction.
    Free, publicly-accessible full text available August 23, 2023