Classroom Card #4453
Think, Act, and Feel Thermodynamics
Summary
Chemical Engineering junior, real-life survival scenario "perfect problem", interdisciplinary thinking
Prerequisites
General Thermodynamics, Heat Transfer (ideally, although not required)
Description
Background
Chemical Engineering Thermodynamics is a very theoretical course, and students often struggle with the use of Equations of State and properties of substances in general, which are needed to solve problems dealing with phase equilibria and also chemical reaction equilibria later in the course. Even though students get familiar with the equations they need to use in order to solve specific problems, they often struggle with basic Thermodynamic concepts and resist to put critical thinking into practice. This “challenge” problem was specially designed as a learning experience that will help students solidify these concepts while making their learning experience an enjoyable process.
Problem Scenario
Two chemical engineering juniors, while hiking in an Arizona National Park at 7500 ft, got lost and stumbled upon a remote wooden cabin. There was no internet connection. The cabin, equipped with drinkable running water, had its power knocked out by a fallen tree, leaving them without electricity. Facing extreme temperature fluctuations—hot days and cold nights—they now need to devise a plan to heat water for a hot meal. With a fire hazard in place, a brand-new stainless steel water hose and thermos available on hand, and any other resources that may be also available in the cabin,
1. Can they successfully heat up the water to enjoy their Ramen noodle soups?
2. Will the water boil inside the hose? What can be done to make that happen?
3. What pressure is developed inside the hose when the water reaches the desired temperature?
Why this? How is it implemented?
This challenge problem is intended as a team assignment that fosters curiosity by encouraging the exploration of ideas, while helping students to recognize a challenge as an opportunity. It promotes making connections through collaboration and engagement with diverse perspectives within a group.
By the deadline set by the instructor, each team is expected to present orally their solutions to the problem in front of peers and the instructor. Every student in the classroom will use a rubric to evaluate all group presentations, except for the presentation done by their own groups. The presentation times may vary depending on class duration and number of presenting groups.
This rubric is provided as an attachment for the reference. According to that rubric, this problem is worth 80 points, and there are also up to 20 additional points that each group could receive based on creativity, attention to details in the presented solution, and depth of understanding as judged by peers and the instructor. This rubric can be modified to make the problem worth differently, as needed.
This problem may be introduced at the beginning of the course to ensure the students have enough time to work on it before they are scheduled to present, which should happen after Equations of State and properties of pure substances are covered.
An opportunity to gain additional bonus points could be given to the groups to make this "the perfect problem" and make this due at the end of the course. If they decide to participate, each group may write a memo to the instructor with changes they want to implement after learning more about Thermodynamics during the course. After attempting the initial plan, students could learn from any failures by analyzing what went wrong, such as not properly managing heat transfer or misjudging the pressure buildup in the hose. In their memo, they might suggest modifications, such as improving insulation techniques or adjusting the hose's exposure to direct sunlight for better heat retention. They may also reconsider using alternative materials that could handle pressure changes more effectively or recalibrate their expectations based on the altitude's impact on water boiling and even expand on safety and environmental considerations. This process would demonstrate their ability to adapt, refine their approach, and learn from own mistakes or oversights to improve outcomes.
Expected Outcomes
A detailed plan outlining how to use the available resources (and any other resources that each team thinks may be also available in the cabin!) to heat water for the soups, including the resulting detailed technical solution and safety and environmental considerations is expected.
Each group is expected to prepare a PowerPoint presentation to present the case during class time by the deadline set by the instructor. The PowerPoint should be provided to the instructor prior to the oral presentations.
If not all the students in each group wish to participate in the "perfect problem" bonus point opportunity, they will still need to list their names in the memo with a note saying that they acknowledge the fact that they will not be eligible for this bonus opportunity but agree on the fact that the other members of the group will be taking advantage of it.
Curiosity
- Demonstrate constant curiosity about our changing world
This challenge problem fosters curiosity by encouraging exploration of ideas, helping students to recognize a challenge as an opportunity. Students can demonstrate curiosity by questioning the physical properties of materials when they explore how a metal conducts heat and how this could help or hinder boiling of the water inside a metal hose. They will investigate the impact of altitude on boiling points and the effect of fluctuating temperatures during hot days on water heating. Although not a great idea due to the fire hazard in place, students may also wonder how to safely build a fire without causing a hazard and may experiment with different heat sources or techniques to increase efficiency. They may dig into the pressure changes inside the hose as the water heats, prompting calculations and exploration of thermodynamic principles and exploring whether a pressure buildup may cause a safety problem. They could even use a chemical reaction (addition of water to some fertilizer that could be available in the cabin) to produce enough heat through an exothermic reaction to heat up water inside the hose. They can also decide not to boil the water, as the cabin is equipped with drinkable running water. Thus, they can use an Equation of State to calculate the pressure inside the hose for pure liquid water. They will also need to decide the hose dimensions depending on how much water they need to heat for their soups.
- Explore a contrarian view of accepted solution
Students can explore a contrarian view by challenging the assumption that traditional methods, like using fire, are the best solution. Instead of relying on heat sources that might pose safety and environmental risks, they could question whether using the thermos to insulate the water or leveraging natural heat (such as sunlight or ground warmth) might be a safer and more efficient alternative. They could also consider the possibility that boiling water in the hose might not be the most practical approach due to pressure concerns and explore whether it’s better to focus on using the thermos or creating a makeshift solar oven, for example.
Connections
- Integrate information from many sources to gain insight
This challenge problem promotes making connections through collaboration and engagement with students with diverse perspectives within a group. Students can integrate information from various sources to solve the problem by drawing on their knowledge of thermodynamics, materials science, and environmental factors. They could research the properties of the metal the hose is made of (their choice!) and its heat conductivity, along with how altitude affects the boiling point of water. Information on fire safety and sustainable heating methods would help them avoid hazards while efficiently heating the water. They could consult principles of pressure and fluid dynamics to understand how the water’s temperature will affect the pressure inside the hose and see if pressure build up may be a potential safety issue.
- Assess and manage risk
Students may explore ideas to heat water without the use of fire and consider safety and environmental considerations. Students can assess and manage risks by first evaluating the fire hazard in the cabin and considering the safest methods to heat the water. They would need to calculate the potential risks of using the hose as a heating element, such as whether the pressure could build up to dangerous levels. By understanding the altitude's effect on boiling points, they can determine how to manage heat sources safely. They could also consider potential environmental risks, like temperature fluctuations or fire spreading, and take precautions by using controlled heat sources or creating insulation to avoid accidents while heating the water effectively.
Creating Value
- Identify unexpected opportunities to create extraordinary value
Students can identify unexpected opportunities by exploring creative ways to use available resources, and whatever else they think could be found in a cabin. For example, they might use the metal water hose as a reflective surface to concentrate sunlight and heat the water, turning a basic material into an effective solar heating tool. They could also explore using the fluctuating temperatures to their advantage, perhaps insulating the hose during the cold night to prevent heat loss or experimenting with the thermos as an insulated storage to retain heat longer. This resourcefulness could lead to discovering innovative ways to solve challenges and maximize limited resources, creating unexpected value in their survival scenario.
- Persist through and learn from failure
Students are given an opportunity to make this "the perfect problem", where they have the chance to write a memo with changes they want to implement after learning more about thermodynamics in the course. After attempting the initial plan, students could learn from any failures by analyzing what went wrong, such as not properly managing heat transfer or misjudging the pressure buildup in the hose. In their memo, they might suggest modifications, such as improving insulation techniques or adjusting the hose's exposure to direct sunlight for better heat retention. They may also reconsider using alternative materials that could handle pressure changes more effectively or recalibrate their expectations based on the altitude's impact on water boiling. This process would demonstrate their ability to adapt, refine their approach, and learn from practical thermodynamics challenges to improve outcomes.
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