MEM-17 Department of Mechanical Engineering and Mechanics Fred Zoback, Eric Prouty, Dwight Bryce Advisors: Bakhtier Far

2. Problem Background The Hess laboratory at Drexel University�s houses a proton exchange membrane (PEM) fuel cell system whose intended use is testing and experimentation as well as a potential backup power source. The power rating of the fuel-cell system is 500 watts and uses 99.95% pure hydrogen as fuel at a pressure of 45 psig. The maximum hydrogen flow rate is 488 l/hr at the rated power rating. With these constraints, a design was implemented to utilize this system as a functional uninterruptible power supply system that can be built using existing technologies.

3. Outline Design Process

4. Problem Statement Design and install the plumbing, electrical, and safety systems for an H-Power EPAC 500 (500 watts) fuel cell system. Evaluate the performance of this system. Determine the operating parameters that define the capacity and functionality. Design an UPS (uninterrupted power supply) system with the plumbing, electrical, and safety systems integrated with the fuel cell system to provide emergency power.

5. Project Schedule Fall. Define objectives and goals. Research Fuel Cell and Hydrogen technologies. Define prototype and production model concepts. Winter. Build prototype, characterized fuel cell, developed production model criteria. Spring. Build and test production model, Thermodynamic analysis.

6. Methods of Solution Develop objectives and design criteria for project. Evaluate potential market needs of a fuel cell powered UPS system. Define parameters of fuel cell system to investigate. Determine prototype requirements to bridge design concept to production model. Define criteria for success.

7. Team Objectives Investigate PEM fuel cell technology. Determine operating parameters and characteristics of PEM fuel cell. Investigate fuel cell efficiencies and potential improvements. Design hybrid power system that utilizes a fuel cell to provide uninterruptible power for end users.

8. Project Design Criteria Provide an uninterruptible electrical power source that provides 500 watts of power that is not time limited by battery capacity. Design will be adaptable to merging hydrogen supply technologies. Implement proper safety systems to operate with hydrogen in various UPS applications.

9. Fuel Cell Markets

10. Investigated Technologies How fuel cells work. Hydrogen storage systems. Hydrogen safety issues. Compare fuel cell technology to conventional small power generators. Investigate fuel cell efficiencies compared to conventional thermal cycles.

11. Prototype Methods of Solution Develop design concept to ensure team can test and analyze fuel cell to develop production model. Determine how H-Power fuel cell system works. Design simple load and control system for prototype testing UPS fuel cell.

12. Production Model Design Concept

13. Prototype Design Concept

14. Prototype Load / Control Design

15. Prototype Load / Control Device

16. Fuel Cell System Components

17. Fuel Cell System Operation

18. Prototype Criteria for Success Be able to evaluate fuel cell operational parameters. Determine how system function. Determine operating characteristics. Provide information to evaluate fuel cell thermal and electro-chemical parameters. System, thermodynamics, voltage, HHV. Compare fuel cell to conventional power generation. Have ability to simulate varied load conditions. Determine requirements on production model to control switching on loss of power and recovery of line power. Safe and functional hydrogen delivery system.

19. Testing and Analysis Methods of Solution Investigate theoretical thermodynamic properties of PEM fuel cells. Operate prototype at various loads and conditions to test fuel cell. Find fuel cell stack power output by measuring voltage, current, hydrogen flow, and stack temp. Find power output from fuel cell system. Determine power used to control fuel cell system.

20. Reversible Fuel Cell

21. PEM Fuel Cell Irreversibility's

22. PEM Fuel Cell Max Voltage / Eff

23. Fuel Cells Vs. Heat Engines Constant temperature energy conversion process is inherently more efficient than the processes in a heat engine The electrochemical conversion process is less irreversible than the combustion reaction Heat engines are defined by the following criteria[1] � ��������� Receives heat from a high temperature source ��������� Converts part of the heat to work ��������� Rejects the remaining waste heat to a low temperature sink ��������� Operates on a thermodynamic cycle � Electrical energy as work / HHV A PEM hydrogen fuel cell meets none of these heat engine criteria, so Carnot cycle efficiency is not useful to analyze fuel cells. The first law concept of comparing net work to energy input can be modified to analyze fuel cells as follows. � [1] Fuel Cell Technology Handbook Edited by Gregor Hoogers CRC Press LLC 2003. pg 3-5 Heat engines are defined by the following criteria[1] � ��������� Receives heat from a high temperature source ��������� Converts part of the heat to work ��������� Rejects the remaining waste heat to a low temperature sink ��������� Operates on a thermodynamic cycle � Electrical energy as work / HHV A PEM hydrogen fuel cell meets none of these heat engine criteria, so Carnot cycle efficiency is not useful to analyze fuel cells. The first law concept of comparing net work to energy input can be modified to analyze fuel cells as follows. �

24. Fuel Cell Voltage Performance

25. PEM Fuel Cell Characterization

26. PEM Fuel Cell Power Characterization

27. PEM Fuel Cell Gas Pressure - Voltage Characterization

28. PEM Fuel Cell Gas Pressure - Power Characterization

29. UPS Fuel Cell Production Model Methods of Solution Use knowledge gained from prototype, testing and analysis work to design production model that meets criteria. Access system via a SWOT analysis. Develop production cost estimates. Build and test production model.

30. SWOT Analysis of Fuel Cell Strengths. What design / product elements work well? Weaknesses. What are design / product weaknesses? Opportunities. Where / how can design /product be improved? Threats. What internal / external threats exist. Strengths ��������� Existing packaged system is simple to operate. Once fuel cell is running there is no need for human interface with the cell. ��������� Grid power is already fed through packaged unit. On power failure and restoration, switching is handled within the fuel cell system. ��������� Turndown ratio appears to be about 10 to 1. Changing loads is handled quickly as long as the load do not have large inrush currents ��������� Quick start up time allows for small UPS system to cover power requirements during cell start up period. ��������� The input and outputs from the fuel cell system that will are required to completely automate system have been identified. Integrating the necessary fuel cell system components into the automated design can be accomplished without a significant level of intrusion. ��������� The manufacturer design fuel cell system with efficiency in mind, as all internal components that use power are controlled to minimize energy use. � Weaknesses ��������� Start-up problems are not well understood. Seems to need to be reset if there is a problem starting. But it is not easy to determine if there is a startup problem until the unit shuts down. ��������� Cannot handle large inrush current for equipment it is rated for at normal operating loads. ��������� No way to know when H2 is running out. (Could be incorporated into design) ��������� There are very limited diagnostic indicators on the fuel cell unit. Diagnostic information is I the form of data accusation and is a proprietary process. The ability to design monitoring instruments will be limited. ��������� To use the fuel cell AC power outlet to feed to an existing lighting circuit from a standard power panel would require additional safety interlocks to prevent back feeding power to inverter output. ��������� Fuel cell system is not suitable for service in electrically classified areas. Must be operated in a fairly clean environment. � Opportunities ��������� Expand to use for higher power output by putting fuel cell systems in parallel. ��������� Manifold H2 source to feed more than one stack and or provide longer time on line. ��������� Compact �simple� design presents potential to design for specific portable applications. ��������� Harden systems to make it suitable in a wider variety of environments. ��������� Back up power supply system can use a variety of hydrogen generating methods as long purity specifications are met. Threats ��������� Require start up time can limit application in communication / computer systems. Because system requires UPS. Unless long-term power is a requirement for end user, a standard UPS systems would be suitable. ��������� Bottled high-pressure hydrogen is presently the easiest fuel source for fuel cell and poses significant safety concerns. Strengths ��������� Existing packaged system is simple to operate. Once fuel cell is running there is no need for human interface with the cell. ��������� Grid power is already fed through packaged unit. On power failure and restoration, switching is handled within the fuel cell system. ��������� Turndown ratio appears to be about 10 to 1. Changing loads is handled quickly as long as the load do not have large inrush currents ��������� Quick start up time allows for small UPS system to cover power requirements during cell start up period. ��������� The input and outputs from the fuel cell system that will are required to completely automate system have been identified. Integrating the necessary fuel cell system components into the automated design can be accomplished without a significant level of intrusion. ��������� The manufacturer design fuel cell system with efficiency in mind, as all internal components that use power are controlled to minimize energy use. � Weaknesses ��������� Start-up problems are not well understood. Seems to need to be reset if there is a problem starting. But it is not easy to determine if there is a startup problem until the unit shuts down. ��������� Cannot handle large inrush current for equipment it is rated for at normal operating loads. ��������� No way to know when H2 is running out. (Could be incorporated into design) ��������� There are very limited diagnostic indicators on the fuel cell unit. Diagnostic information is I the form of data accusation and is a proprietary process. The ability to design monitoring instruments will be limited. ��������� To use the fuel cell AC power outlet to feed to an existing lighting circuit from a standard power panel would require additional safety interlocks to prevent back feeding power to inverter output. ��������� Fuel cell system is not suitable for service in electrically classified areas. Must be operated in a fairly clean environment. � Opportunities ��������� Expand to use for higher power output by putting fuel cell systems in parallel. ��������� Manifold H2 source to feed more than one stack and or provide longer time on line. ��������� Compact �simple� design presents potential to design for specific portable applications. ��������� Harden systems to make it suitable in a wider variety of environments. ��������� Back up power supply system can use a variety of hydrogen generating methods as long purity specifications are met. Threats ��������� Require start up time can limit application in communication / computer systems. Because system requires UPS. Unless long-term power is a requirement for end user, a standard UPS systems would be suitable. ��������� Bottled high-pressure hydrogen is presently the easiest fuel source for fuel cell and poses significant safety concerns.

31. Control System Solution Use UPS to provide instantaneous power in event of a power failure. Control System will manage automatic start up of fuel cell. Hydrogen Fuel will be feed automatically and monitored for leaks.

32. Control System Design Solution

33. Control Hardware

34. Controller Panel

35. Fuel Feed System

36. Control Panel Power Control

37. Testing and Commissioning Ensure design functions as designed. Simulated power failures. Logic validation. Ensure safety systems function. Test hydrogen shutdown system. Test alarm functions.

38. Estimated Costs

39. Team Work Define Process Eric- Hydrogen Storage; Fred- Research Technology; Dwight- Safety Prototype Fred- Design; Dwight & Eric- Evaluation Testing and Analysis Fred, Eric, Dwight � Load, Pressure, Power output, Efficiency, Thermodynamics Production Model Fred- Controller Design, Construction Dwight - Construction; Eric- Construction, Power Switching & Plumbing Design

40. Summary Researched fuel cell technologies to create a hybrid uninterrupted back up power supply system. Designed and built prototype to enable testing and analysis to take design from concept to production model. Build and tested functional production model that can be manufactured with existing technologies.