A N A M E R I C A N N A T I O N A L S T A N D A R D

FUEL CELL POWER SYSTEMS PERFORMANCE

PERFORMANCE TEST CODES

ASME PTC 50-2002

Date of Issuance: November 29, 2002

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CONTENTS

Foreword v

Committee Roster vii

Board Roster viii

INTRO. .D. .U. C. .T.I.O. N 1

1. Object and Scope 2

   1. Object 2

   2. Scope 2

   3. Test Uncertainty 2

2. Definition and Description of Terms 3

   1. Introduction 3

   2. Fuel Cell Types 3

   3. Fuel Cell Power Systems 4

   4. General Fuel Cell Nomenclature 5

   5. General Definition 5

3. Guiding Principles 8

   1. Introduction 8

   2. Agreements 8

   3. Test Boundary 8

   4. Test Plan 8

   5. Preparation for Test 10

   6. Parameters to be Measured or Determined During the Test Period 11

   7. Operation of the Test 14

   8. Calculation and Reporting of Results 14

   9. Records 15

4. Instruments and Methods of Measurement 16

   1. General Requirements 16

   2. Checklist of Instruments and Apparatus 18

   3. Determination of Outputs 19

   4. Determination of Fuel Input 20

   5. Data Collection and Handling 22

5. Computation of Results 23

   1. Introduction 23

   2. Computation of Inputs 23

   3. Computation of Electric Power Output 27

Figures

2.1 Generic Fuel Cell Power System Diagram 4

1. Generic Fuel Cell System Test Boundary 9

2. Fuel Cell System Test Boundary Illustrating Internal Subsystems 9

Tables

3.1 Maximum Permissible Variations in Test Operating Conditions 14

4.1 Potential Bias Limit for Heating Values 21

Mandatory Appendix

I Uncertainty Analysis and Sample Calculation 33

FOREWORD

During the mid 1990s the importance of developing fuel cell standards was recognized. Fuel Cell power plants were in the early stages of commercialization. Potential applications included vehicular power, on-site power generation, and larger scale dispersal power generators. There was a growing demand to produce industry standards that would keep pace with the commercialization of this new technology.

ASME had a very active Fuel Cell Power Systems technical committee within the Advanced Energy Systems Division. Through its volunteer membership, it recommended the formation of a standards committee to work on developing a fuel cell standard. ASME Codes and Standard Directorate undertook this task. On October 14, 1996 the Board on Performance Test Codes voted to approve the formation of a performance test code committee, PTC 50.

This Committee had its f rst meeting on January 23-24, 1997. The membership consisted of some 18 fuel cell experts from Government, academia, manufacturers, and users of fuel cells. Ronald L. Bannister; Westinghouse Electric Corporation; retired, chaired the f rst meeting. He had been appointed by the Board on PTC as the Board Liaison member to the committee. He chaired and supervised the committee’s activities until permanent off cers were elected from the membership.

In the Fall 2001, the Committee issued a draft of the proposed Code to Industry for review and comment. The comments were addressed in February 2002 and the Committee by a letter ballot voted to approve the document on March 29, 2002. It was then approved and adopted by the Council as a standard practice of the Society by action of the Board on Performance Test Codes voted on May 6, 2002. It was also approved as an American National Standard by the ANSI Board of Standards Review on July 3, 2002.

NOTICE

All Performance Test Codes MUST adhere to the requirements of PTC 1, GENERAL INSTRUCTIONS. The following information is based on that document and is included here for emphasis and for the convenience of the user of this Supplement. It is expected that the Code user if fully cognizant of Parts I and III of PTC 1 and has read them prior to applying this Supplement.

ASME Performance Test Codes provide test procedures which yield results of the highest level of accuracy consistent with the best engineering knowledge and practice currently available. They were developed by balanced committees representing all concerned interests. They specify procedures, instrumentation, equipment operating requirements, calculation methods, and uncertainty analysis.

When tests are in accordance with a Code, the test results themselves, without adjustment for uncertainty, yield the best available indication of the actual performance of the tested equipement. ASME Performance Test Codes do not specify means to compare those results to contractual guarantees. Therefore, it is recommended that the parties to a commercial test agree before starting the test and preferably before signing the contract on the method to be used for comparing the test results to the contractual guarantees. It is beyond the scope of any Code to determine or interpret how such comparisons shall be made.

PERSONNEL OF PERFORMANCE TEST CODE COMMITTEE 50

FUEL CELL POWER SYSTEMS PERFORMANCE

(The following is the roster of the Board at the time of approval of this Code.)

OFFICERS

1. J. Leo, Chair

K. Hecht, Vice Chair

J. H. Karian, Secretary

COMMITTEE PERSONNEL

D. H. Archer, Carnegie Mellon University

P. J. Buckley, Energy Alternatives

S. Comtois, H Power Enterprises of Canada, Inc.

1. S. Frick, SCANA Corp.

2. Hecht, UTC Fuel Cells

F. H. Holcomb, U.S. Army Corps of Engineers

J. H. Karian, The American Society of Mechanical Engineers

B. Knaggs, Ballard Generation Systems

M. Krumpelt, Argonne National Laboratory

A. J. Leo, Fuel Cell Energy

A. Skok, Alternate, Fuel Cell Energy

R. M. Privette, OMG Corp.

L. A. Shockling, Siemens-Westinghouse Power Corp.

R. P. Wichert, U.S. Fuel Cell Council

M. C. Williams, U.S. DOE, NETL

BOARD ON PERFORMANCE TEST CODES

OFFICERS

S. J. Korellis, Chair

J. R. Friedman, Vice Chair

W. O. Hays, Secretary

COMMITTEE PERSONNEL

ASME PTC 50-2002

FUEL CELL POWER SYSTEMS PERFORMANCE

INTRODUCTION

Fuel cells convert the energy of a fuel directly into electricity, eliminating the combustion stage that is characteristic of heat engines, and not requir- ing any moving parts. Instead, the fuel molecules (usually hydrogen often derived from hydrocarbon fuels) interact with the surface of an anode material to form reaction products, liberating electrons. The electrons flo through the electric load to the cath- ode where they react with an oxidant, typically oxygen from air. Ions migrate between the electrodes through the ionically conducting electrolyte to com- plete the circuit. The product of this electrochemical energy conversion process is water, but unlike heat engines, the process can take place at close to ambient temperature, or can also be conducted at higher temperatures, depending on the types of anode, electrolyte, and cathode materials.

Since fuel cells are not heat engines, the efficienc of a fuel cell system is not limited by the Carnot principle. It can, in fact, vary over a fairly wide range. When the current density of the fuel cell is very low, the energy conversion eff ciency ap- proaches the ratio of the Free Energy of Combustion of the fuel divided by the Enthalpy of Combustion. For methane this limit is 94%. However, such an operating mode would require a very large fuel cell and would be too expensive in most applications.

In practice, fuel cell systems are designed to operate at a power density reflectin the most eco- nomical trade-off of fuel and capital costs. At the design point of the system the power output of the system is specifie by the manufacturer for certain standard conditions of fuel and air. It is the purpose of this Code to defin in a commonly acceptable manner how the power output and the energy input should be measured and how the efficienc should be calculated.

Section 1 define the objective and scope of this Code. Section 2 is dedicated to definin a fuel cell system and to definition of terms. It also contains a brief discussion of the major types of fuel cells. In Section 3, methodology of establishing test proto- col is outlined. Instrumentation for measuring the energy of the feed stream as well as of the exiting gases and liquids is given in Section 4, as is the instrumentation for measuring electric power. Sec- tion 5 describes how the efficienc of the systems shall be calculated from the measurements, and how corrections for nonstandard conditions shall be made.

Typically, this performance test code would be used for an independent verificatio of the perform- ance of a particular fuel cell system by a customer or test agency. In the view of the members of the Committee, the described procedures are rigorous, and the test will require committing significan re- sources. For the casual user of fuel cells, it will suffic to determine the electric output of the system under steady state conditions, and to measure the fuel feed rate. As mentioned above, the efficienc of a fuel cell system varies significantl with power density. At power densities below the design point, the efficienc will usually increase, and it will de- crease when the power output exceeds the design point. One of the characteristics of fuel cells is the ability to operate them over a wide power range, even exceeding the design point by 50% for a few minutes. Under dynamic operating conditions the efficienc of a fuel cell would be different than at the design point, and would probably be higher, since most loads contain significan segments of low-power operation and normal system control (e.g., for fuel flow responds fairly quickly to these load conditions. Measuring the efficienc under dy- namic conditions goes beyond the scope of the document.

ASME PTC 50-2002 FUEL CELL POWER SYSTEMS PERFORMANCE

SECTION 1 OBJECT AND SCOPE

1. OBJECT

   This Code provides test procedures, methods, and def nitions for the performance characterization of fuel cell power systems. Fuel cell power systems include all components required in the conversion of input fuel and oxidizer into output electrical and thermal energy. Performance characterization of fuel systems includes evaluating system energy inputs and electrical and thermal outputs to determine fuel- to-electrical energy conversion eff ciency and where applicable, the overall thermal effectiveness. These eff ciencies will be determined to an absolute uncer- tainty of less than ±2% at a 95% conf dence level. (For example, for a calculated eff ciency of 40%, the true value lies between 38% and 42%.)

   
   

2. SCOPE

   This Code applies to all fuel cell power systems regardless of the electrical power output, thermal output, fuel cell type, fuel type, or system application. Fuel cell power systems contain an assembly of electrochemical cells, which oxidize a fuel to gener- ate direct current electricity. Balance-of-plant subsys- tems may include controls, thermal management, a fuel processor and a power conditioner. Some fuel cell power systems may contain additional power generating equipment such as steam generators, gas turbine generators, or micro-turbine generators. The net power output and all the fuel input to the system shall be taken into account in the performance test

   calculations.

   This Code applies to the performance of overall fuel cell power systems. The Code addresses com- bined heat and power systems, that is, the generation of electricity and usable heat at specif c thermal conditions. It does not address the performance of specif c subsystems nor does it apply to energy storage systems, such as regenerative fuel cells or batteries. It also does not address emissions, reliabil- ity, safety issues, or endurance.

   This Code contains methods and procedures for conducting and reporting fuel cell system testing,

   including instrumentation to be used, testing tech- niques, and methods for calculating and reporting results.

   The Code def nes the test boundary for fuel and oxidant input, secondary energy input and net electri- cal and thermal energy output. At these boundaries, this Code provides procedures for measuring temper- ature, pressure, input fuel f ow and composition, electrical power, and thermal output.

   The Code provides procedures for determination of electrical eff ciency or heat rate and overall thermal effectiveness at rated or any other steady-state condi- tion. The Code also provides the method to correct results from the test to reference conditions.

3. TEST UNCERTAINTY

In accordance with ASME PTC 19.1, procedures are provided for determining the uncertainty associ- ated with the calculated performance parameters of this Code (energy input, electrical energy and thermal outputs, and electrical eff ciency or heat rate). In the measurements made to determine performance parameters, there are systematic errors produced by the procedures and instrumentation recommended in this Code. A table of these systematic errors may be found in Section 4 of this Code.

Sample calculations of the uncertainties associated with the system performance parameters, which illus- trate the effects of systematic errors and data, are presented in Mandatory Appendix I of this Code.

A pretest uncertainty analysis is recommended. The pretest analysis allows corrective action to be taken prior to the test, which will either decrease the uncertainty to an appropriate level consistent with the overall objective of the test or will reduce the cost of the test while still attaining the test uncertainty.

A post-test uncertainty analysis is mandatory. It will make use of empirical data to determine random measurement errors and test observations to establish whether or not the required uncertainty has been achieved.

This uncertainty procedure serves as a guide for pretest and post-test uncertainty calculations when the Code is used.