1. CACHE Modules on Energy in the Chemical Engineering Curriculum: Fuel Cells Jason Keith 1, Don Chmielewski 2, H. Scott Fogler 3, Valarie Thomas 3 1 Department of Chemical Engineering Michigan Technological University 2 Department of Chemical and Biological Engineering Illinois Institute of Technology 3 Department of Chemical Engineering University of Michigan

2. Outline Introduction and Motivation What is in each module? Where are the modules? What are the modules? Module walk-through Conclusions / Acknowledgments

3. Introduction and Motivation Alternative energy component missing from most departments Fuel Cells have been discussed in the political arena as an alternative energy solution –Need to educate ChE’s in this area Growth in number of fuel cell textbooks –Most do not have homework problems Modules can rapidly infuse new technologies into the Chemical Engineering Curriculum

4. What is in each module? Problem motivation Reference to related sections and pages in popular ChE texts Example problem statement Example problem solution Home problem statement Home problem solution Link to web resources Non-ChE textbook resources Notes to instructor

5. Where are the modules? Current beta test website: http://www.chem.mtu.edu/~jmkeith/fuel_cell_curriculum Currently available for use by anyone! Ultimately linked through CACHE website

6. What are the modules? Mass and Energy Balances –Application of Heat of Reaction: Hydrogen vs. Gasoline –Material Balances on a Fuel Cell –Energy Balances on a Fuel Cell –Generation of Electricity Using Recovered Hydrogen

7. Thermodynamics –Equation of State for Fuel Cell Gases –Thermodynamics and Fuel Cell Efficiency –Vapor Pressure / Humidity for Fuel Cell Gases Fluid Mechanics –Friction Factor in Bipolar Plate Channel What are the modules?

8. Heat and Mass Transport –Conduction and Convection Heat Transfer in Fuel Cells –Microscopic Balances Applied to Fuel Cells –Diffusion Coefficients for Fuel Cell Gases Kinetics and Reaction Engineering –Nernst Equation and Fuel Cell Kinetics –Using Plug Flow Reactor Equations for Fuel Cell Voltages What are the modules?

12. Module walk-through How long can you power a laptop computer with a type K hydrogen cylinder (49.9 L)? H 2 tankFuel Cell H 2 feed line Computer (Electric Load) Anode Gas Chamber Cathode Gas Chamber H 2 and H 2 O out Air in Air out

13. Module walk-through Course: Material and Energy Balances (Stoichiometery) Title: Application of Heat of Reaction: Hydrogen versus gasoline Motivation: Use the heat of reaction to determine the energy contained in a hydrogen cylinder, and determine the equivalent number of gallons of gasoline. Reference: Felder and Rousseau, Section 4.6(3 rd ed.) Each module has reference to popular text(s) for the course

14. Module Example Problem Example Problem: Determine energy generated for the combustion of a gallon of gasoline Step 1) Determine  H r for gasoline components  H r,C7H16 = 7  H CO2 + 8  H H2O -  H C7H16 – 11  H O2  H r,C7H16 = -4816 kJ/mol Step 2) Similarly:  H r,C8H18 = -5461 kJ/mol Each example has an easy to follow step-by-step approach

15. Module Example Solution Step 3) Weighted average (87% n-heptane and 13% isooctane):  H r,gas = -5370 kJ/mol Step 4) Determine mass in grams of components in 1 mol of gasoline: 13.0 g n-heptane and 99.2 g isooctane Step 5) Determine volume of these components: The total volume is 162 cm 3 or 0.043 gal Step 6) Determine energy per gallon: -5370 kJ/mol /(1 mol/0.043 gal) = -125,000 kJ/gal

16. Module Hwk Problem How many kJ are there in a K cylinder of H 2 ? How many gallons of gas is this equivalent to? How many gallons of water do you make from the hydrogen in the gas cylinder? What is the maximum time you could power a 100 W laptop with this H 2 cylinder?

17. Currently open to everyone; final version will be password protected Recommend printing example and statement and giving to students as a handout Rest of step-by-step solution available at end of talk Module Hwk Solution How many kJ are there in a K cylinder of H 2 ? Assume liquid water product,  H r,H2O = -286 kJ/mol From ideal gas law, cylinder contains n = 278 mol Energy content = -n  H r,H2O = 79000 kJ

18. Conclusions / Acknowledgments Fuel Cell Modules are for your use! Contact one of the authors to participate Acknowledgments of Partial Support: –CACHE Corporation –JMK: DOE(DE-FG02-04ER63821), NSF(DMI-0456537), and the Michigan Space Grant Consortium –DJC: Argonne National Laboratory –HSF / VT: Vennema Professorship and Thurnau Professorship

19. Module Hwk Solution How many kJ are there in a K cylinder of H 2 ? Assume liquid water product,  H r,H2O = -286 kJ/mol From ideal gas law, cylinder contains n = 278 mol Energy content = -n  H r,H2O = 79000 kJ

20. Module Hwk Solution How many gallons of gas is this equivalent to? Assume 112 g/mol and density 0.69 g/cm 3 Recall gasoline heat of reaction = -5370 kJ/mol Thus, hydrogen cylinder is equivalent to 14.7 mol gasoline Converting to mass we have 1646 g and then converting to volume gives 0.63 gal

21. Module Hwk Solution How many gallons of water do you make in a fuel cell? Stoichiometry tells us 278 mol of H 2 react to form 278 mol H 2 O This is equivalent to 5000 g or 1.32 gal

22. Module Hwk Solution What is the maximum time you could power a 100 W laptop with this H 2 cylinder? To determine the upper bound on time we assume all hydrogen is converted into electricity (100% efficiency). At a power of 100 W, 79000 kJ of energy would be consumed in 219 hours. In reality, you could expect the fuel cell to operate for 100 hours.