Chemical Engineering Thermodynamics Project

Solomon Scurry, Aaron Bennett, and Dan Burleson, University of Houston, College of Engineering
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This activity was selected for the Teaching Computation in the Sciences Using MATLAB Exemplary Teaching Collection

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This page first made public: Aug 23, 2019

Summary

This activity is a project designed to introduce undergraduate chemical engineering students to chemical engineering thermodynamics in the context of MATLAB. The project requires students to learn concepts they will encounter in their thermodynamics courses, such as the first law of thermodynamics and applying it to a system to perform an energy balance, the difference between state and path functions, and the refrigeration cycle and the role that condensers, heat exchangers, expansion valves, evaporators, and compressors play in it.

Learning Goals

Ideally, all new concepts the students learn are strictly related to thermodynamics. These include:
- Learning the first law of thermodynamics and how to apply it to a defined system or piece of equipment to perform an energy balance
- The difference between state and path functions
- The refrigeration cycle and the role that condensers, heat exchangers, expansion valves, evaporators, and compressors play in it

MATLAB is mainly used as a problem-solving tool for this project. It allows students to learn that MATLAB can be used to aid their chemical engineering studies, and allows them to relate the concepts they learn in MATLAB to real-world problem solving in the context of chemical engineering. The technical skills that students are expected to have going into this project are mostly related to concepts learned in calculus, such as the evaluation of integrals. Furthermore, this project requires students to be able to take physical and chemical laws and apply them to a system boundary in order to solve for unknowns.

Context for Use

The project is designed to be completed in an introductory general engineering course at a university, preferably before the students have taken a thermodynamics course. The project can be completed individually or in a small group of 2-3 students. If this is the setting, the project should take 2-3 weeks to complete. To complete the project, students need to be able to import data from an Excel file, check for negative values within the imported data set using for loops, receive user inputs and perform data validation tasks using while loops and conditionals, and use the fzero and integral functions. As this project is designed to introduce students to thermodynamics, no prior thermodynamics knowledge is needed. While this project is used in a course based on engineering problem-solving, particularly using MATLAB as a tool, it can also easily be used as a simple example for preliminary concepts in an introductory thermodynamics course.

Description and Teaching Materials

As stated in the project goals, this should be an assignment that introduces students to chemical engineering thermodynamics. As such, we require that students solve the problem by hand prior to coding in MATLAB in order to ensure that they have a solid foundation in the concepts that the project requires.

After students have mastered the thermodynamics concepts for the project, they can begin coding their solutions in MATLAB.

The materials provided are listed below:
- Project instructions
- Excel data file
- Rubrics
- Solutions zip file (containing handwritten solution, code solution main script, code solution function, test case screenshot) - Instructor Access Only


Data is provided using the following webpages:
https://www.chemours.com/Refrigerants/en_US/assets/downloads/h47752_hfc134a_thermo_prop_si.pdf
https://www.ohio.edu/mechanical/thermo/property_tables/R134a/
Project Description (Microsoft Word 2007 (.docx) 91kB Aug13 19)
Project Data (Excel 2007 (.xlsx) 33kB Aug13 19)
Project Rubrics (Microsoft Word 2007 (.docx) 98kB Aug13 19)

Teaching Notes and Tips

If this project is used in a course before students take thermodynamics, it is useful for students to take the time to learn a few important concepts before attempting the problem:
- The first law of thermodynamics
- The difference between state and path functions
- The application of Gibb's phase rule in determining how many pieces of information must be given in order to define a system
- What it means for a liquid or vapor to be saturated
- How to obtain properties from a saturated table

We have seen much better results when students learn these particular concepts prior to attempting to solve the problem. Also, it is beneficial for students to complete the project by hand prior to coding it in MATLAB. The deadlines set forth in the "Assessment" portion help guarantee that students do this.

This project spans a few weeks in our course with multiple deadlines along the way. However, you may see fit to omit or consolidate some deadlines.

Assessment

The goals of the activity are assessed using the rubrics provided. A short description of each rubric and how they relate to the goals is provided below:
- Deadline A is used to assess student knowledge of the first law of thermodynamics. Furthermore, it requires that students understand the equipment involved in the refrigeration cycle and how the first law of thermodynamics can be applied to each piece of equipment and simplified in order to complete an energy balance.
- Deadline B is used to assess how well students understand the interconnectedness of the refrigeration cycle. While deadline A had students perform energy balances on each individual piece of equipment, deadline B forces students to make an algorithm for solving the entire problem. Students must be able to know how the user inputs provided allow them to solve for all remaining unknowns in the system.
- Deadline C is focused on making sure students understand how their handwritten solutions and algorithms translate into MATLAB. This deadline makes sure that students know how to import their data, receive user inputs and complete data validations, and use temperature inputs for two saturated streams in order to determine enthalpy of these streams.
- Deadline D is the final submission and is designed to ensure students understand the full refrigeration cycle. Students are required to solve for all stream enthalpies, as well as the work needed to power the compressor and heat removed from the external system.

References and Resources

Additional resources that may be provided for students are listed below:
1. http://faculty.poly.edu/~rlevicky/Handout6.pdf
2.https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Thermodynamics/Fundamentals_of_Thermodynamics/State_vs._Path_Functions
3. https://web.iit.edu/sites/web/files/departments/academic-affairs/academic-resource-center/pdfs/Thermodynamic_Property_Tables.pdf
4. https://www.araner.com/blog/vapor-compression-refrigeration-cycle/