Session: 09-04-02: Fluid Mechanics, Aerospace, Thermodynamics, Heat Transfer, and Energy Systems

Paper Number: 98430

98430 - Industry-Based Thermodynamics Case Study on Refrigeration Cycle 

Case study learning methodology has been used for more than 20 years in teaching science and engineering. This methodology is known to be highly effective in promoting students’ understanding of the concepts and improving their ability to make connections between the concepts. In 2020 and 2021, the limited access to laboratory equipment and facilities due to the COVID-19 pandemic encouraged instructors to implement alternative methods to hands-on experiments. One of the alternatives considered in the current institution is the use of case studies to enhance students’ understanding of thermodynamics and fluid mechanics topics during the online implementation of those courses.

In this study, an industry-based air-conditioning (AC) unit is facilitated to prepare a case study to teach refrigeration cycles in a thermodynamics course. All four components of the AC unit, which includes a compressor, a condenser, an expansion valve, and an evaporator, are assembled on a single platform. In an actual application, the compressor and condenser are part of the outside unit while an evaporator and expansion valve would be located indoors. A typical AC unit operation involves compression of the refrigerant in the compressor, condensation of the refrigerant as it transfers heat to the outside air, expansion of the refrigerant through throttle valve, and evaporation of the refrigerant as it absorbs heat from the inside air. To evaluate refrigerant properties, thermocouples and pressure sensors are installed at the inlet and exit from each component of the AC unit. At the first phase of the case study, students analyze temperature and pressure data for the normal operation of the unit to understand the function of each component in the cycle. In addition, by using thermodynamics property tables, they determine enthalpy and entropy values at different stages of the process, generate a temperature versus entropy (T-s) diagram, and calculate the efficiency of the AC unit. In the second phase of the study, they are provided with temperature and pressure data collected and they perform the analysis of the data when there is a problem with the AC unit. The examples of issues introduced include part of the condenser or evaporator coils being disabled or using a partially blocked air filter. The equipment used in the case study is modified by the manufacturer to simulate those issues.  During data analysis, student teams are tasked with identifying the issue introduced by looking at the changes in temperature, pressure, and T-s diagram. This paper provides detailed information about the case study, data collection, and analysis.

Presenting Author: Emine Foust NA

Presenting Author Biography: Emine Celik Foust is currently an Associate Professor at York College of Pennsylvania. In 2008, she worked as a Postdoctoral Research Associate in Mechanical Engineering Department at Johns Hopkins University. She received her Master of Science and Ph.D degrees in Mechanical Engineering from Lehigh University.<br/><br/>Emine Celik Foust’s research interests include the design and development of engineering systems using analytical and experimental approaches. Areas of application include flow-induced vibrations, flow around bluff bodies, airfoils, perforated plates, cavity configurations, and biomedical devices.

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