Bei-jiann Chang, Donald W. Johnson, and Christopher P. Garcia

QSS Group, Inc., Cleveland, Ohio

Ian J. Jakupca

Analex Corporation, Brook Park, Ohio

Vincent J. Scullin and David J. Bents

Glenn Research Center, Cleveland, Ohio

Regenerative Fuel Cell Test Rig

at Glenn Research Center

NASA/TM—2003-212375

July 2003

AIAA–2003–5942

https://ntrs.nasa.gov/search.jsp?R=20030068063 2018-05-15T18:32:35+00:00Z
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Bei-jiann Chang, Donald W. Johnson, and Christopher P. Garcia

QSS Group, Inc., Cleveland, Ohio

Ian J. Jakupca

Analex Corporation, Brook Park, Ohio

Vincent J. Scullin and David J. Bents

Glenn Research Center, Cleveland, Ohio

Regenerative Fuel Cell Test Rig

at Glenn Research Center

NASA/TM—2003-212375

July 2003

National Aeronautics and

Space Administration

Glenn Research Center

Prepared for the

First International Energy Conversion Engineering Conference

cosponsored by the American Institute of Aeronautics and Astronautics

(AIAA), the American Society of Mechanical Engineers (ASME), and the

Institute of Electrical and Electronics Engineers (IEEE)

Portsmouth, Virginia, August 17–21, 2003

AIAA–2003–5942
Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

This report is a preprint of a paper intended for presentation at a conference. Because

of changes that may be made before formal publication, this preprint is made

available with the understanding that it will not be cited or reproduced without the

permission of the author.

Available electronically at http://gltrs.grc.nasa.gov
NASA/TMó2003-212375 1 

REGENERATIVE FUEL CELL TEST RIG AT GLENN RESEARCH CENTER 

Bei-jiann Chang, Donald W. Johnson, and Christopher P. Garcia 

QSS Group, Inc. 

Cleveland, Ohio 44135 

Ian J. Jakupca 

Analex Corporation 

Brook Park, Ohio 44142 

Vincent J. Scullin*

 and David J. BentsÜ

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

ABSTRACT

The regenerative fuel cell development effort at Glenn 

Research Center (GRC) involves the integration of a 

dedicated fuel cell and electrolyzer into an energy 

storage system test rig. The test rig consists of a fuel 

cell stack, an electrolysis stack, cooling pumps, a water 

transfer pump, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), 

heat exchangers, isolation valves, pressure regulators, 

interconnecting tubing, nitrogen purge provisions, and 

instrumentation for control and monitoring purposes. 

The regenerative fuel cell (RFC) thus formed is a 

completely closed system which is capable of autonomous cyclic operation. The test rig provides direct 

current (DC) load and DC power supply to simulate 

power consumption and solar power input. In addition, 

chillers are used as the heat sink to dissipate the waste 

heat from the electrochemical stack operation. Various 

vents and nitrogen (N2) sources are included in case 

inert purging is necessary to safe the RFC test rig. 

NOMENCLATURE

ASME American Society of Mechanical Engineers 

DC Direct Current 

ERAST Environmental Research Aircraft and Sensor 

Technology 

GRC Glenn Research Center 

IEA Integrated Equipment Assembly 

I/O Input/Output 

NASA National Aeronautics and Space 

 Administration 

PC Personal Computer 

PEM Proton Exchange Membrane 

PID Proportional Integral Derivative 

RFC Regenerative Fuel Cell 

VI Virtual Instrument 

INTRODUCTION

The NASA GRC supports the development of an 

aerospace hydrogen-oxygen RFC under the Environmental Research Aircraft and Sensor Technology 

(ERAST) project of the Flight Research Base Program. 

The ERAST charter includes the development and 

demonstration of new technologies for unmanned 

aircraft that are suitable for earth science, including 

RFC equipped solar electric aircraft with potentially 

unlimited endurance. Although ERAST is an Aeronautics project, the RFC as a solar energy storage device is 

applicable to a wide variety of space and planetary 

surface missions as well as high altitude solar electric 

flight; hence, the widespread interest throughout NASA 

to bring this technology to a flight demonstration. 

Potentially the highest storage capacity and lowest 

weight of any non-nuclear device, an RFC aboard a 

solar electric aircraft flown continuously through 

several successive day-night cycles will provide the 

most convincing demonstration that this technology's 

widespread potential has been realized. Leading up to 

the flight demonstration are several laboratory and full 

scale demonstrations of key components and subsystems, including the coordinated operation of a hydrogen-oxygen fuel cell and electrolyzer unit as an energy 

storage system in a sealed, closed loop environment. 

*

Scientific Applications Development Branch 

Ü

Thermo-Mechanical Systems Branch 
NASA/TMó2003-212375 2 

BACKGROUND

A test stand for evaluating Proton Exchange Membrane 

(PEM) electrolyzers has been in operation at GRC since 

January 2000. The stacks tested there include 4-cell, 

8-cell short stacks, and full size prototype stacks that 

consumed 15 kWe power to generate O2 and H2 at 

pressures up to 400 psig. A test stand for characterizing 

PEM fuel cells was also constructed at GRC, and has 

been in operation since September 2000. The stacks 

that were tested on this stand include 4-, 8-, and 10 cell 

short stacks, and full size prototype stacks that produced up to 5.25 kWe from O2 and H2 reactant gasses 

at pressures up to 400 psig. 

Both test stands ran on a once-through basis, i.e., no 

recycling of O2, H2, and water. The next step in the 

GRC test program was to combine the fuel cell and 

electrolyzer to form a closed loop RFC as an energy 

storage system based on the experiences gained in 

operating the two stand-alone test stands. The specific 

objectives of the RFC test rig were to simulate diurnal 

charge/discharge cycles, to observe long term performance of RFC, and to identify any degradation 

mechanisms. 

The RFC design ground rules shown in Table 1 were 

set forth in the beginning of the test rig development. 

The RFC design specifications were based on solar 

airplane energy storage requirements and electrochemical stack availabilities. Interface requirements shown in 

Table 2 defined electrical and fluidic connections 

between the RFC and the test support equipment. A 

process block diagram for the regenerative fuel cell test 

rig was developed as in Figure 1. 

TABLE 1.óDESIGN GROUNDRULES FOR 

REGENERATIVE FUEL CELL TEST RIG 

1. Use commercial off-the-shelf and fabricated components 

to build a working rig initially. 

2. Provide flexibility to incorporate flight-like components 

later. 

3. Include additional sensors for data collection. 

4. Provide O2 and H2 venting capabilities. 

5. Provide N2 purging and vacuum charging as service 

interfaces, not part of the rig. 

6. Provide capability for collecting gas and water grab 

samples. 

TABLE 2.óREGENERATIVE FUEL CELL INTERFACE 

REQUIREMENTS 

Input Power: 0 to15 kW (150A@100.0V) 

Output Power: 0 to 5.25 kW (100A@52.5V) 

Maximum Heat Rejection: 4.48 kW (15,290 BTU/HR) 

Maximum Inlet Coolant Temperature to Heat Exchanger: 

50 °C 

Maximum Exit Coolant Temperature from Heat Exchanger: 

54 °C 

Minimum Inlet Coolant Temperature to 1st Dryer: 0 °C 

Maximum Exit Coolant Temperature from 1st Dryer: 5 °C 

Minimum Inlet Coolant Temperature to 2nd Dryer: 

ñ40 °C 

Maximum Exit Coolant Temperature from 2nd Dryer: 

ñ30 °C 

Dimensions: 4 ft*6.5 ft*8 ft (Excluding O2 and H2 Storage 

Tanks) 

The following sections describe the mechanical/ 

electrochemical design, operational concepts, operating 

modes, control definitions, control/monitor instrumentation, primary control and LabVIEW controller as well 

as test support equipment. 

MECHANICAL/ELECTROCHEMICAL DESIGN

A mechanical schematic was developed based on the 

RFC design requirements and specifications. One 

important design issue had to be resolved before the 

RFC system design could be finalized; the operating 

pressure of the fuel cell stack. Because of the difficulties the stack developers experienced in sealing the fuel 

cell stack at high pressures, pressure regulators were 

incorporated to allow low-pressure (50-psig) fuel cell 

operations. A water transfer pump was added to deliver 

water produced from the fuel cell to the eletrolyzer. 

Dedicated phase separator tanks were also added. The 

mechanical schematic reflecting these design decisions 

was prepared as shown in Figure 2, which details the 

process block diagram shown in Figure 1 into the 

following three interconnected process sections: 2(a) 

Fuel Cell; 2(b) Electrolyzer; 2(c) Reactant Storage 

Tanks and Driers. The major components list of the 

RFC is contained in Table 3 that includes the schematic 

symbol and description of each major component. 
NASA/TMó2003-212375 3 

Primary control

Primary

PC-based

LabVIEW

controller

Backup

PC-based

LabVIEW

controller

Coolant

N2 purge

Compressed air

Coolant

H2/N2 purge

O2/N2 purge

DC power DC load

Safety signals

AC/DC power

Figure 1.—Regenerative fuel cell test rig process block diagram. 

AC power Control/monitor instrumentation External signals

Electrolyzer Fuel cell

H2

tank/

dryer

O2

tank/

dryer

H2O

Figure 2a.—Fuel cell.
NASA/TMó2003-212375 4 

Figure 2b.—Electrolyzer.
NASA/TMó2003-212375 5 

Figure 2c.—Reactant storage tanks and dryers.
NASA/TMó2003-212375 6 

TABLE 3.óRFC COMPONENT LIST 

Schematic Symbol Description 

CL 111 Thermocouple, Type T 

CL 113 Flow Meter, Turbine 

CL 115 Thermocouple, Type T 

CL 144 Pump, Cooling 

DI 102 Thermocouple, Type T 

DI 110 Flow Meter, Turbine 

DI 150 Pump, Transfer 

DI 154 Pump, Cooling 

DI 201 Valve, Ball, Pneumatic 

DI 202 Valve, Ball, Pneumatic 

EZ 1 ñ 60 Electrolyzer Cell Voltage tabs 

EZ 101 Electrolyzer Stack Current shunt 

EZ 102 Electrolyzer Stack Voltage 

FC 1 ñ 64 Fuel Cell Cell Voltage tabs 

FC 101 Fuel Cell Stack Current shunt 

FC 102 Fuel Cell Stack Voltage 

FH 104 Flow Meter, Laminar 

FH 105 Pump, Recirculation 

FH 113 Storage Tank, ASME Pressure Vessel 

FH 114 Contaminant Sensor 

FH 139 Pressure Regulator, Back 

FH 140 Phase Separator, Hydrogen 

FH 201 Valve, Ball, Pneumatic 

FH 202 Pressure Regulator 

FH 203 Scale 

FH 240 Phase Separator, Hydrogen 

HX 101 Heat Exchanger, Shell and Tube 

HX 102 Heat Exchanger, Shell and Tube 

WB 107 Dryer, First 

WB 108 Dryer, First 

WB 109 Dryer, Second 

WB 110 Dryer, Second 

XO 103 Scale 

XO 104 Flow Meter, Laminar 

XO 105 Pump, Recirculation 

XO 113 Storage Tank, ASME Pressure Vessel 

XO 114 Contaminant Sensor 

XO 121 Sensor, Level 

XO 139 Pressure Regulator, Back 

XO 140 Phase Separator, Oxygen 

XO 142 Thermocouple, Type T 

XO 201 Valve, Ball, Pneumatic 

XO 202 Pressure Regulator 

XO 203 Scale 

XO 240 Phase Separator, Oxygen 

All mechanical/electrochemical components and fluid 

interconnections are packaged within a frame to form 

the Integrated Equipment Assembly (IEA), except for 

Unpowered

(D)

Shutdown

(B)

Normal

(A)

Purge

(C)

 A B C

From all modes

4 Modes

3 Operating modes

8 Mode Transitions

5 Programmable, allowed mode transitions

Figure 3.—RFC operating modes and allowable 

 mode transitions.

the gas storage tanks and their associated sensors and 

valves. The IEA and an instrumentation cabinet are 

housed inside a shelter. The shelter is in turn located 

inside a building that serves as the safety barricade 

during RFC testing when people are not allowed in the 

test area. The tanks and associated hardware are sited 

outdoors on opposite sides of the building. 

If a fuel cell stack is capable of operating at pressures 

up to the electrolyzerís maximum pressure, the RFC 

schematic could be simplified by eliminating the 

additional cooling pump DI154, water transfer pump 

DI150, forward pressure regulators XO202 and FH202, 

as well as phase separators XO240 and FH240. The 

comparison of the high-pressure with the low- pressure 

fuel cell stacks in the RFC was discussed previously 

(Ref. 1). The current test rig may be converted to the 

ìsimplifiedî system at a later time when high-pressure 

fuel cell stacks become available. 

OPERATIONAL CONCEPTS

During the period of time in which electrical energy is 

available to be stored, DC electrical power from the 

energy source (i.e., solar array) is applied to the 

electrolyzer stack. While the electrolyzer is generating 

the O2 and H2 product gases, the stack temperature is 

controlled by the water flow rate with waste heat 

rejected through heat exchanger HX102. Water 

consumed on the anode side causes the water level in 

O2 phase separator XO240 to decrease and is replenished from the fuel cell O2 phase separator XO140 via 

water transfer pump DI150. The water transported to 

the cathode side by association to migrating protons 

causes the water level of the H2 phase separator FH240 

to rise and is drained periodically by opening valve 

DI201 and closing valve DI202. Product gases O2 and 
NASA/TMó2003-212375 7 

H2 flow through separators XO240 and FH240 to drop 

out bulk liquid water. The gases then pass through 1st 

dryers WB107 and WB108 to lower the dew point 

temperature to 40 °F followed by 2nd dryers WB109 

and WB110 to further lower dew point temperature 

below ñ20 °F. The water condensed in the 1st dryers is 

drained back into the phase separators. The water vapor 

that has changed to ice is stored in the 2nd dryers to be 

thawed and returned to the fuel cell stack during the 

next cycle. The dried gases are delivered to reactant 

storage tanks XO113 and FH113 against rising 

pressures. 

When the electrical energy source is no longer available 

(i.e., nightfall), or when the reactant storage tank has 

been filled to its 400 psig pressure limit, the DC power 

supplied to the electrolyzer is turned off. Valves XO201 

and FH201 open to allow reactants O2 and H2 to flow 

into the fuel cell stack at a stepped down pressure of 

50 psig via pressure regulators XO202 and FH202. The 

current draw from the fuel cell will ramp up to the full 

power of 5.25 kWe. Adjusting the pump CL144 motor 

speed that controls the coolant flow rate through the 

stack and heat exchanger HX101 maintains the fuel cell 

stack temperature. The reactants recirculate through the 

stack using pumps XO105 and FH105. A fixed 

stoichiometric ratio relative to the current draw is 

maintained by adjusting the pump speed in response to 

temperature or pressure changes. The O2 recirculation 

also ensures the water produced on the cathode side is 

removed from the stack and stored in the O2 phase 

separator XO140. The set point of chiller coolant for 

the 2nd dryer is raised to 68 °F to thaw the ice and 

humidify the reactants to the fuel cell. When sufficient 

daylight returns or the tank pressure drops below 

50 psig, the RFC switches back to electrolyzer operation and starts another diurnal cycle. 

Water quantities in the system are monitored by weight 

sensors on the phase separators which allow the 

operator to track reactant inventory. Contaminant 

sensors are placed in the O2 and H2 flow streams near 

the phase separators and storage tanks to detect the 

presence of combustible mixtures due to gas cross over 

in the electrochemical stacks. N2 purge is available for 

the electrolyzer stack plus its phase separators, fuel cell 

stack, and fuel cell phase separators. The reactant 

storage tanks can be depressurized if necessary by 

venting to ambient. 

OPERATING MODES

The RFC operates in one of following four modes: 

Unpowered, Shutdown, Normal, and Purge. Each mode 

produces different settings and control states in how the 

RFC is operated. Definitions for each of these operating 

modes is presented in Table 4. Figure 3 illustrates the 

RFC operating modes and allowable mode transitions. 

Details of the individual mode transitions are contained 

in the ìRFC Day Cycle Programî control software 

presented in the ìPrimary control and LabVIEW 

Controllerî discussion section of this paper. 

TABLE 4.óRFC MODE DEFINITIONS 

Mode Definition 

Shutdown The electrolyzer is not generating H2 and O2 and the 

fuel cell is not generating power. Both stack currents 

are at zero and all actuators are deenergized. The 

system is powered and all sensors are working. The 

Shutdown mode is called for by: 

• Manual actuation 

• High FC stack temperature 

• High EZ stack temperature 

• Low FC cell voltage 

• High EZ cell voltage 

• Low EZ cell voltage 

• High FC O2 outlet temperature 

• High FC H2 outlet temperature 

• High EZ O2 outlet temperature 

• High EZ H2 outlet temperature 

• High FC cooling water outlet temperature 

• High EZ water conductivity 

• High O2 concentration in H2 phase separator 

• High H2 concentration in O2 phase separator 

• High O2 concentration in H2 storage tank 

• High H2 concentration in O2 storage tank 

• High EZ O2 outlet pressure 

• High EZ H2 outlet pressure 

• High FC O2 inlet pressure 

• High FC H2 inlet pressure 

• High EZ H2/O2 pressure differential 

• Low EZ H2/O2 pressure differential 

• High FC H2/O2 pressure differential 

• Low FC H2/O2 pressure differential 

• High FC O2/water pressure differential 

• Low FC O2/water pressure differential 

• Low water pump flow 

• High O2 storage tank pressure 

• High H2 storage tank pressure 

• High O2 storage tank temperature 

• High H2 storage tank temperature 

• Low O2 phase separator level 

• Low H2 phase separator level 

• High H2 phase separator level 

• High facility H2 concentration 

• High facility fire detection 

• FieldPoint watchdog timer failure 
NASA/TMó2003-212375 8 

TABLE 4.óRFC MODE DEFINITIONS (Concluded) 

Mode Definition 

Normal The RFC is performing its function, either storing H2

and O2 with the electrolyzer operating according to the 

power profile or generating electrical power at 

5.25 kWe with the fuel cell. The Normal mode is called 

for by: 

• Manual actuation 

Purge The RFC is being purged with N2 or vented. There are 

four options available: purging electrolyzer stack, 

purging fuel cell stack, venting fuel cell phase separator 

tanks, or venting storage tanks. The Purge mode is 

called for by: 

• Manual actuation 

Unpowered

 

No electrical power is applied to the RFC. The RFC is 

at the pressure and temperature when the power was 

lost. The Unpowered mode is called for by: 

• Manual actuation (turn switch) 

• Electrical power failure 

CONTROL DEFINITIONS

The process controls for the RFC are listed in Table 5 

along with the associated process parameters, actuators, 

sensors, set points, and ranges. The first six controls are 

set point changes based on given profiles or conditions. 

The recirculation flow rate controls and stack 

temperature controls are feed back controls that require 

proportional, integral and derivative (PID) control 

algorithms. Their block diagrams are shown in 

Figures 4 to 7. 

CONTROL/MONITOR INSTRUMENTATION

National Instrumentsí FieldPointô input/output (I/O) 

modules are used to modularize the communication, I/O 

functions, and signal termination of the RFC sensors 

and actuators. These units are networked using one 

primary and two backup personal computers (PCís) to 

perform data acquisition and control functions using 

Ethernet bus topology. Use of Field Point via an 

ethernet bus was selected for this test rig due to the 

need to site the rig in an isolated location and operate it 

remotely (safety purposes) and the large number of 

instruments and actuators aboard, which would 

otherwise need >750 ft of hard wired connections for 

each instrument. A fiber optic cable and Ethernet multiport managed switching hubs provide the link between 

the control room and the shelter location where the rig 

is sited. Most sensors and actuators in the rig are wired 

to the FieldPoint distributed modules except for those 

with RS232 and RS485 serial links that are directly 

connected to the switching hub at the rig. The data link 

block diagram is presented in Figure 8. 

TABLE 5.óCONTROL DEFINITIONS FOR RFC 

No. Name Actuator(s) Sensor(s) Setpoint(s) Range(s) 

1 Electrolyzer Current Power Supply EZ101 Variable per Profile 0 to 150 A 

2 Fuel Cell Current Electronic Load FC101 100 A 0 to 100 A 

3 H2 and O2 2nd Dryer High Temperature Chiller N/A 20 °C 0 to 25 °C 

4 H2 and O2 2nd Dryer Low Temperature Chiller N/A ñ40 °C ñ40 to ñ30 °C 

5 EZ H2 Phase Separator Level N202 (DI201,DI202) 

Energized on high 

Deenergized on low 

FH121 High: 18 in. 

Low: 8 in. 

4 to 22 in. 

6 EZ O2 Phase Separator Level DI150 

Powered on low 

Unpowered on high 

XO121 High: 18 in. 

Low: 8 in. 

4 to 22 in. 

7 H2 Recirculation Flow Rate FH105 FH104 58 slpm 0 to 60 slpm 

8 O2 Recirculation Flow Rate XO105 XO104 45 slpm 0 to 60 slpm 

9 Electrolyzer Temperature DI154 XO142 

XO142ñDI102 

158 °F 

15 °F 

68 to 178 °F 

0 to 18 °F 

10 Fuel Cell Temperature CL144 CL111 

CL111ñCL115 

158 °F 

15 °F 

68 to 178 °F 

0 to 18 °F 
NASA/TMó2003-212375 9 

Facility fire and H2 detectors are placed around the 

test rig in accordance with the applicable safety 

standards (Ref. 2). A close circuit television is 

installed to provide the operator in the control room 

with audiovisual monitoring of the test rig site. 

PRIMARY CONTROL AND LABVIEW 

CONTROLLER

The Primary Control relay logic circuit provides 

manual switching of power to RFC and emergency 

shutdown capabilities. The facility fire and H2

sensors relay circuit also triggers emergency RFC 

shutdown if an alarm level is reached. Lights on the 

panel indicate the system power status. In addition, a 

reset button is provided to clear a latched emergency 

shutdown condition. All faults must be resolved to 

complete a system-reset operation. The block 

diagram for Primary Control is illustrated in Figure 9. 

At the center of the PC-based LabVIEW controller is 

the RFC Day Cycle Program that consists of a 

Figure 4.—H2 recirculation flow rate control loop.

PID control

Pump

FH105

Fuel cell

stack

FH104

+

RFC day cycle program

H2 from 

tank

-

Based on 

FC101

FH104

Set point

Figure 5.—O2 recirculation flow rate control loop.

PID control

Pump

XO105

Fuel cell

stack

XO104

+

RFC day cycle program

O2 from 

tank

-

Based on 

FC101

XO104

Set point

PID Control

Pump

DI154

Electrolyzer

stack

Set point

XO142

XO142

Heat 

exchanger

+

From 

chiller

To 

chiller

-

DI102

PID Control

Delta T

+ Set point -

RFC day cycle program 

Figure 6.—Electrolyzer temperature control loop.
NASA/TMó2003-212375 10 

PID Control

Fuel cell

stack

Set point

CL111

CL111

Heat 

exchanger

+

From 

chiller

To 

chiller

-

CL115

PID Control

Delta T

+ Set point -

RFC day cycle program 

Figure 7.—Fuel cell temperature control loop.

Pump

CL144

I/O

module

Primary

PC-based

LabVEIW controller

Inter-building fiber link

Control room

Ethernet multiport managed switching hub

Backup

PC-based

LabVEIW controller

Max (9) I/O

modules per bank

Modular distributed I/O

for primary control and status

To ethernet

switch

(1) port 100 Base-TX

(1) port 100 Base-TX

High-Speed local bus formed by linked terminal bases

Ethernet 

network 

module

(1) port 100 

Base-TX

Instrument 

duct bank,

approximately

750 ft from

control room 

to test rig

Figure 8a.—Regenerative fuel cell serial data signal topology.
NASA/TMó2003-212375 11 

11 banks required, only 1 bank shown for clarity

Modular distributed I/O and control system

 for sensors and actuators

Figure 8b.—Regenerative fuel cell serial data signal topology.

High-speed local bus formed by linked terminal bases

I/O

module

Ethernet

network

module

Max (1024) banks per

ethernet segment

High-speed local bus formed by linked terminal bases

I/O

Module

Ethernet

network

module

Max (9) I/O

modules per bank

From 

fiber

link

Portable shelter

Ethernet 

multiport 

managed 

switching 

hub

(1) port 100 Base-TX

(1) port 100 

Base-TX

(1) port 100 Base-TX

Diagnostic

PC-based

LabVEIW 

controller

Electronic

load

2nd stage 

dryer chiller

Electronic 

press. reg.

Electronic 

press. reg.

FC O2 phase separator

 weight scale

EZ H2 phase separator

 weight scale

EZ O2 phase separator

 weight scale

Portable Shelter

Ethernet/

serial

RS232 

interface

Figure 8c.—Regenerative fuel cell serial data signal topology.

Ethernet 

multiport 

managed 

switching 

hub

(1) port RS-232C

(1) port RS-232C

(1) port RS-232C

Ethernet/

serial

RS232 

interface

(1) port RS-485 (1) port 

100 Base-TX

(1) port 

100 Base-TX

Ethernet/

serial

RS232 

interface

(1) port RS-232C

(1) port RS-232C

(1) port RS-232C

(1) port 

100 Base-TX

From 

fiber

link

 Outside portable shelter 

 (max distance 50 ft)

DC power supply
NASA/TMó2003-212375 12 
NASA/TMó2003-212375 13 
NASA/TMó2003-212375 14 
NASA/TMó2003-212375 15 

supervisory virtual instrument (VI) and multiple 

independent VIs called by the supervisory VI. The 

software program performs the following tasks: 

sequencing mode transition and cyclic operation, 

converting and displaying sensor readings in engineering units, running control algorithms, limit checking for 

warnings and alarms, writing data to files for future 

retrieval, and providing operator interfaces with the 

RFC. 

The Day Cycle program is designed to run simultaneously on all three of the RFC computers under a 

master/slave paradigm. As each computer is brought 

on-line, it listens for a master "heartbeat" from the other 

PCs. If it does not hear the heartbeat, it starts itself up 

as the master and begins transmitting the master 

heartbeat. If it does hear the heartbeat on startup, it 

designates itself as a slave. The role of the master is to 

acquire all of the system data and publish that data to 

the slaves, as well as to operate all of the system 

controller software. The slave PCs can read the data 

from the master and display it, and observe, but not 

direct, all of the controller operations. The slave PCs 

also listen continuously for the master heartbeat. If that 

heartbeat should ever disappear, in evidence of a loss of 

power or functionality on the part of the existing 

master, then the slave PCs initiate an automatic transfer 

of authority to make one of them the new master. 

Which slave becomes the new master depends on: (a) 

which one first detects the master has dropped out, and 

(b) where its IP address appears on a predetermined 

hierarchy list (diagnostic PC comes last). Because the 

same Day Cycle program runs on all three PCs, any of 

the three can operate as the master and the RFC system 

can run with one, two, or all three of the PCs on-line. 

The primary "master" PC and one "slave" PC reside in 

the control room. The second "slave" PC resides at the 

remote site in an instrumentation cabinet next to the 

equipment, where it is also used for checkout and 

diagnostic purposes. The front panels of the main 

screen VI and the process display VI are shown in 

Figures 10 and 11, respectively. 
NASA/TMó2003-212375 16 

TEST SUPPORT EQUIPMENT

The test support equipment includes a DC power 

supply, a DC electronic load, a main chiller, a 1st dryer 

chiller, a 2nd dryer chiller, a vacuum pump, N2 bottles 

and compressed air. They are commercially available 

hardware that provides the interfaces for the RFC 

testing. Table 6 summarizes the specifications of the 

test support equipment. 

TABLE 6.óTEST SUPPORT EQUIPMENT 

Item Specification 

DC Power Supply 200A @ 150V 

DC Electronic Load 12 kWe with 1000A max.

Main Chiller 10 kWe @ 5 gpm 

1st Dryer Chiller 200 W @ 1 °C 

2nd Dryer Chiller 100 W @ ñ40 °C 

Vacuum Pump <80 mbar 

N2 K bottle >450 psig 

Compressed Air 80 to 120 psig 
NASA/TMó2003-212375 17 

CONCLUSIONS

This test rig was built up over calendar year 2002ñ03 

and is presently undergoing mechanical, electrical and 

software checkout. Figure 12 is a photograph of the 

IEA with the fuel cell stack and electrolyzer stack 

shown in the foreground. 

Checkout operations of individual process sections per 

Figures 2(a), 2(b), and 2(c) will commence as soon as 

the initial checkout is completed. The coordinated 

operation of fuel cell and electrolyzer subsystems as 

end-to-end energy storage system is scheduled to take 

place before the end of fiscal year 2003. Additional 

characterization tests and inclusion of latest generation 

of fuel cell and electrolyzer stacks are planned for the 

future. 

REFERENCES

1. Michael A. Dornheim, ìSpecial Fuel Cells Key to 

Months-Long Flight,î Aviation Week & Space 

Technology, February 28, 2000. 

2. NASA Glenn Research Center Safety Manual, 

NHB 1700.1, National Aeronautics and Space 

Administration, 1997. 
This publication is available from the NASA Center for AeroSpace Information, 301–621–0390.

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Cleveland, Ohio 44135–3191

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Available electronically at http://gltrs.grc.nasa.gov

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NASA TM—2003-212375

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23

Regenerative Fuel Cell Test Rig at Glenn Research Center

Bei-jiann Chang, Donald W. Johnson, Christopher P. Garcia

Ian J. Jakupca, Vincent J. Scullin and David J. Bents

Regenerative fuel cells; Energy storage

Unclassified -Unlimited

Subject Categories: 07, 20, and 44 Distribution: Nonstandard

Prepared for the First International Energy Conversion Engineering Conference cosponsored by the American Institute of Aeronautics

and Astronautics (AIAA), the American Society of Mechanical Engineers (ASME), and the Institute of Electrical and Electronics

Engineers (IEEE), Portsmouth, Virginia, August 17–21, 2003. Bei-jiann Chang, Donald W. Johnson, and Christopher P. Garcia, QSS

Group, Inc., Cleveland, Ohio 44135; Ian J. Jakupca, Analex Corporation, Brook Park, Ohio 44142; Vincent J. Scullin and David J.

Bents, NASA Glenn Research Center. Responsible person, David J. Bents, organization code 5490, 216–433–6135.

The regenerative fuel cell development effort at Glenn Research Center (GRC) involves the integration of a dedicated

fuel cell and electrolyzer into an energy storage system test rig. The test rig consists of a fuel cell stack, an electrolysis

stack, cooling pumps, a water transfer pump, gas recirculation pumps, phase separators, storage tanks for oxygen (O2)

and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, interconnecting tubing, nitrogen purge

provisions, and instrumentation for control and monitoring purposes. The regenerative fuel cell (RFC) thus formed is a

completely closed system which is capable of autonomous cyclic operation. The test rig provides direct current (DC)

load and DC power supply to simulate power consumption and solar power input. In addition, chillers are used as the

heat sink to dissipate the waste heat from the electrochemical stack operation. Various vents and nitrogen (N2) sources

are included in case inert purging is necessary to safe the RFC test rig.