Kenneth A. Burke

Glenn Research Center, Cleveland, Ohio

Ian J. Jakupca and Anthony J. Colozza

Analex Corporation, Cleveland, Ohio

Development of Passive Fuel Cell Thermal 

Management Heat Exchanger

NASA/TM—2010-216892

December 2010
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Kenneth A. Burke

Glenn Research Center, Cleveland, Ohio

Ian J. Jakupca and Anthony J. Colozza

Analex Corporation, Cleveland, Ohio

Development of Passive Fuel Cell Thermal 

Management Heat Exchanger

NASA/TM—2010-216892

December 2010

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
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NASA/TM—2010-216892 1

Development of Passive Fuel Cell Thermal 

Management Heat Exchanger

Kenneth A. Burke

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Ian J. Jakupca and Anthony J. Colozza

Analex Corporation

Cleveland, Ohio 44135

Abstract

The NASA Glenn Research Center is developing advanced passive thermal management technology 

to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration 

program. The passive thermal management system relies on heat conduction within highly thermally 

conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the 

fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop 

components within the fuel cell system which reduces mass and improves overall system reliability. 

Previous development demonstrated the performance of suitable highly thermally conductive cooling 

plates that could conduct the heat, provide a sufficiently uniform temperature heat sink for each cell of the 

fuel cell stack, and be substantially lighter than the conventional thermal management approach. Tests 

were run with different materials to evaluate the design approach to a heat exchanger that could interface 

with the edges of the passive cooling plates. Measurements were made during fuel cell operation to 

determine the temperature of individual cooling plates and also to determine the temperature uniformity 

from one cooling plate to another.

Introduction

The purpose of this work was to test different heat exchanger designs, materials, and vacuum grease. 

The heat exchanger would interface with the edges of the very thermally conductive passive cooling 

plates of the fuel cell thermal management system. The cooling plates used in these tests were previously 

developed at NASA and had thermal conductivities of 1400 to 1500 W/m/K (Ref. 1).

Nomenclature

A Cooling plate cross sectional area, m2

dT/dx Temperature gradient, K/m

k Thermal conductivity, W/m-K

Q Applied heat, W

T Cooling plate temperature, K

x Location of the temperature measurement on the cooling plate, m

Background

The heart of a fuel cell is an electrochemical “cell” where a fuel and an oxidizing agent react, 

converting the chemical energy directly into electrical power, water and waste heat. The fuel cells used by 

NASA are hydrogen-oxygen fuel cells. The fuel cells under development for future NASA missions are 
NASA/TM—2010-216892 2

acid-based Proton Exchange Membrane (PEM) hydrogen-oxygen fuel cells. An illustration of this type of 

cell is shown in Figure 1. A hydrogen molecule reacts at the anode to create a pair of protons and 

electrons. The proton ion exchange membrane conducts the protons, which were generated at the anode,

from the anode to the cathode. The electrons which were also generated at the anode are conducted 

through the electrical load that is connected to the fuel cell and also reach the cathode. The hydrogen 

protons and the electrons are reacted at the cathode with an oxygen atom to produce a molecule of water. 

An illustration of a “stack” of cells connected electrically in series is shown in Figure 1.

Heat must be removed from the fuel cell stack to prevent the stack from overheating. Heat is typically 

removed from the fuel cells via cooling plates within the fuel cell stack that are located between the cells 

as shown in Figure 1. Typically a liquid coolant is circulated within the plate and heat is removed 

convectively as the coolant passes through the plate and out of the fuel cell stack to a fuel cell system heat 

exchanger. A passive cooling plate must conduct the heat within the plane of the plate out to one or more 

of the edges of the plate so that the heat can be transferred to a heat exchanger external to the fuel cell 

stack. Figure 2 shows the difference between a conventional fuel cell thermal management system and a 

passive fuel cell thermal management system. Potential benefits of the passive approach include 

reductions in mass, system complexity, and parasitic power as well as improvements in system reliability. 

Figure 3 plots the fuel cell heat generation density (the heat generated per unit of cell area) versus the 

fuel cell output current density (Ref. 2). NASA’s fuel cell applications typically optimize in the lower 

current density range (≤400 mA/cm2

), so the heat generation expected from NASA’s fuel cells is 

generally ≤0.3 W/cm2

. 

Figure 1.—Proton exchange membrane fuel cell.
NASA/TM—2010-216892 3

Figure 2.—Fuel cell thermal management systems.

Current density, mA/cm2

Figure 3.—Fuel cell heat generation

The key to making the passive approach workable is making the cooling plates light enough, yet 

highly thermally conductive, so that the heat can be effectively removed and also provide each cell in the 

fuel cell stack a thermally uniform heat sink. Analytical expressions were developed (Ref. 2) that relate

the thermal performance of a passive cooling plate to its physical characteristics. There are two key 

metrics used in the evaluation of the thermal management system, the first is the maximum temperature 

difference, the ∆T, over the chemically active area of each cell in the fuel cell stack. Ideally, a uniform 

temperature over the active area is desired because this maximizes the electrochemical performance 

throughout the stack. In practice, a ∆T of zero is never achieved because the process of removing waste 

heat from the fuel cell always requires a temperature differential. In practice, a ∆T of 3 °C has been 

acceptable, and therefore was used as a driving requirement. A second key metric is the mass of the 

thermal management system. The waste heat managed per unit mass of the thermal management system 

was the defined metric for mass evaluation. The thermal system mass was considered to be the mass of

the cooling plates internal to the fuel cell stack and the mass of thermal system components external to the Cell heat density, W/cm2
NASA/TM—2010-216892 4

Figure 4.—Cooling plate heat transmission distance, thermal conductivity, and plate 

specific gravity.

fuel cell stack such as the coolant, plumbing lines, pump, accumulator, sensors, etc. The mass of the fuel 

cell system heat exchanger common to both approaches was excluded from the mass of the thermal 

system. The space shuttle fuel cell powerplant has a maximum heat rejection of 7322 W and an overall 

mass of 115.7 kg (Ref. 3). The fraction of the overall shuttle fuel cell powerplant mass represented by the 

thermal system was not known but estimated to be 10 percent. This would result in a waste heat per unit 

mass of 633 W/kg. A value of 1000 W/kg was used as a goal for the passive thermal management system.

Using 1000 W/kg as the value of the metric and 3 °C as the ∆T, the relationship between heat 

transmission distance L, the specific gravity of the cooling plate ρ, and the thermal conductivity k of the 

cooling plate is plotted in Figure 4 using the analytical relationships developed (Ref. 2).

From the plot shown in Figure 4, it is apparent that for fuel cells which have to transmit the heat 

≥4 cm, a thermal conductivity of ≥ 1000 W/m/K and a specific gravity of ≤4 gm/cc would be required to 

meet the metric targets. 

Interface Heat Exchanger Test Articles

Interface heat exchanger test articles were fabricated from aluminum, stainless steel, copper, 

thermally conductive plastic supported on aluminum, and anodized aluminum. Table 1 lists the properties 

of the materials from which the integrated heat exchangers were made (Refs. 4 and 5). 

TABLE 1.—INTEGRATED HEAT EXCHANGER MATERIAL PROPERTIESa

Material Density 

(g/cm3)

Thermal conductivity 

(W/mK)

Specific heat capacity

(J/g°C)

Coefficient of linear 

thermal expansion 

(×10-6/°C)

C10100 Copper 8.94 391 0.39 17.7

316 Stainless Steel 7.94 15 0.47 16

6061-T6 Aluminum 2.7 180 0.896 23.6

D5506 LCP 1.8 10 0.97 6.4 to 11.3 a

Properties listed are for approximately room temperature or for an unstated temperature.
NASA/TM—2010-216892 5

Aluminum, Stainless Steel, and Copper Heat Exchangers

Three integrated metal heat exchangers were fabricated with identical geometries. The only difference

between the heat exchangers was the material. The heat exchangers were made of aluminum, stainless 

steel, and copper. A picture of the different heat exchangers is shown in Figure 5.

Two of each type were used in each test. Thermally conductive pyrolytic graphite/copper cooling 

plates previously developed (Ref. 1) were slide into the slots of the pair of heat exchangers. The cooling 

plates were approximately 100 mm (4 in.) by 100 mm (4 in) with a thickness of 0.0009 mm (0.23 in) and 

a thermal conductivity of 1400 W/m/K. Figure 6 shows four cooling plates inserted into one of the pair of 

heat exchangers. The other heat exchanger was removed so the inserted cooling plates could be more 

easily seen.

Figure 7 is an illustration of the assembled test article configuration, showing four cooling plates 

inserted between the two heat exchangers. Each cooling plate was instrumented with twelve 

thermocouples spaced as shown in Figure 7. A silicone pad heater was adhered to the other side of each 

plate, so that on one side of each plate were the thermocouples, and on the opposite side of each plate was 

the silicone pad heater.

Figure 5.—Aluminum, stainless steel, and copper heat exchangers.

Figure 6.—Heat exchanger with inserted cooling plates.
NASA/TM—2010-216892 6

Figure 7.—Aluminum, stainless steel, and copper heat exchanger test article configuration.

Figure 8.—Plastic/aluminum heat exchangers. Figure 9.—Assembled plastic/aluminum heat exchanger 

configuration.

Thermally Conductive Plastic/Aluminum Heat Exchanger

An integrated heat exchanger was made using a thermally conductive plastic from Cool Polymers 

(Ref. 5). The final configuration of a heat exchanger must not produce an electrical shorting path between 

cells in a fuel cell stack. The plastic, in this case, provides the necessary insulation between the cooling 

plates. The properties of this polymer were listed in Table 1. The plastic plate was epoxied onto an 

aluminum rectangular channel. Aluminum endcaps with tube fittings closed the ends of the rectangular 

channels. Threaded rods held the two heat exchangers onto the four inserted cooling plates. Figures 8 and 

9 show a picture of the fabricated plastic/aluminum heat exchangers and the assembled plastic/aluminum 

heat exchanger test article configuration. 

Figure 10 is an illustration showing the dimensions of the plastic/aluminum heat exchanger test 

article. The four cooling plates were the same plates as those used in the testing of the metal heat 

exchangers. 
NASA/TM—2010-216892 7

Figure 10.—Plastic/aluminum heat exchanger test article 

configuration dimensioned.

Single-Sided Thermally Conductive Plastic/Aluminum Heat Exchanger

A single-sided plastic/aluminum heat exchanger was designed and fabricated. The single-sided heat 

exchanger was designed to be integrated with a functional fuel cell stack. The plastic portion of this heat 

exchanger used two of the plastic pieces previously used in the construction of the plastic/aluminum heat 

exchanger shown in Figures 8, 9 and 10. These two plastic pieces were epoxied to a single, rectangular 

aluminum channel. The cross sectional dimensions of this heat exchanger were identical to the cross 

1.184 in.

0.197 in.

0.135 in.

1.0 in.

1.5 in.

0.029 0.266 in. in.

0.125 in.

0.125 in.

0.065 in.

Adhesive layer 

~0.005 in. thick
NASA/TM—2010-216892 8

sectional dimensions of one side of the double-sided heat exchanger shown in Figure 10. The single-sided 

heat exchanger is shown in Figure 11.

The cooling plates to be inserted into the fuel cell stack would extend beyond the exterior of the fuel 

cell stack and fit within the slots machined into the plastic pieces. Pictures of the cooling plate design are 

shown in Figures 12 and 13. Four of these cooling plates were made. Silicone pad heaters were adhered to

one side of each cooling plate. The other side of each cooling plate was instrumented with nine 

thermocouples.

Figure 14 illustrates the geometry of the cooling plates used with the single sided plastic aluminum 

heat exchanger. Figure 14 also shows the location of the silicone pad heater. The pad heater mimicked the 

quantity of heat expected from each cell in the fuel cell stack. The area and placement of the heater

similarly mimicked the area and location where the heat would be produced by each cell in the fuel cell

stack. Figure 14 also shows the number and placement of the thermocouples used to measure the 

temperature of each cooling plate. The holes in the cooling plate at the top and bottom of the plate are for 

the hydrogen and oxygen manifolds within the fuel cell stack, but played no functional role in the 

experiment of the heat exchangers. Figure 15 shows the assembled singled-sided plastic/aluminum heat 

exchanger with instrumented cooling plates.

Figure 11.—Single-sided plastic/aluminum heat exchanger.

Figure 12.—Fuel cell cooling plate with pad heater. Figure 13.—Fuel cell cooling plate with thermocouples.
NASA/TM—2010-216892 9

Figure 14.—Fuel cell cooling plate showing location of the pad heater and thermocouples.

Figure 15.—Single-sided plastic/aluminum heat exchanger assembled with 

fuel cell cooling plates.

Anodized Aluminum Heat Exchanger

A second single-sided heat exchanger was designed and fabricated. This heat exchanger used an 

anodized aluminum coating as the electrical insulation layer between the different cooling plates. The 

cooling plates from the previous single-sided heat exchanger test article were reused with the anodized 

heat exchanger. Figure 16 shows an illustration of the anodized aluminum heat exchanger with the 

cooling plates.

Figure 17 shows the fabricated anodized heat exchanger. The cooling plates were inserted into the 

anodized heat exchanger the same depth as they were into the plastic aluminum heat exchanger. Instead 
NASA/TM—2010-216892 10

of a single rectangular coolant flow passage, the anodized heat exchanger used five smaller diameter flow 

channels that carried coolant down the length of the heat exchanger and were connected in parallel to 

common manifold aluminum blocks.

Figure 16.—Single-sided anodized aluminum heat exchanger with fuel cell 

cooling plates.

Figure 17.—Fabricated anodized aluminum heat exchanger.
NASA/TM—2010-216892 11

Interface Heat Exchanger Testing

The cooling plates were inserted into each different type of heat exchanger. Tests were run with and 

without vacuum grease. The vacuum grease was applied to the ends of the cooling plates such that it filled 

the void spaces between the edges of the cooling plates and the walls of the grooves into which the 

cooling plates were inserted. The heat exchanger testing consisted of applying different known heat rates

to each of the heated pads that were attached to each plate, and removing the heat by flowing coolant 

through the heat exchanger. Temperature measurements made on the face of each plate gave a measure of 

the temperature distribution of each plate and how well the heat exchanger was allowing the heat to be 

transferred to the coolant. These measurements allowed the comparison of the performance of the 

different heat exchanger designs.

Heat Exchanger Testing Facilities

The heat exchangers and cooling plates were tested in a vacuum chamber shown in Figure 18. Figure 

19 shows the interior of the chamber including of the heat exchangers with the inserted cooling plates.

The tests were run at vacuum conditions to minimize convective heat transfer from the test article and to 

ensure that heat conduction from the cooling plates to the heat exchanger was the predominant heat 

transfer mechanism. This approach simplified the analysis of the data. Radiative heat losses from the 

samples during the test were negligibly small in comparison to the heat being conducted through the plane 

of the cooling plate.

Coolant plumbing lines were run from the test article to a feed-through in the vacuum tank wall, and 

from there to a temperature controlled chiller bath located outside of the vacuum chamber. Power lines 

from the cartridge heaters were run to a feed-through in the vacuum tank wall and from there to a DC 

power supply located outside of the vacuum chamber. Leads for thermocouples were similarly run to a 

feed-through and from there to a computer to record the temperature data. Figure 20 illustrates the overall 

heat exchanger test rig.

Figure 18.—Heat exchanger vacuum test chamber.
NASA/TM—2010-216892 12

Figure 19.—Vacuum chamber interior with test article.

Figure 20.—Overall heat exchanger test rig configuration.
NASA/TM—2010-216892 13

Interface Heat Exchanger Testing Results

Aluminum Heat Exchanger Test Results

The aluminum heat exchanger shown in Figures 5 and 7 was tested in the heat exchanger vacuum 

chamber. The electrical power applied to the four cooling plates was varied from 2.5 to 22.5 W per plate. 

The heaters on each plate had an area of 58 cm2

. The heat density was therefore 0.04 to 0.39 W/cm2. As 

stated earlier, NASA’s fuel cells are expected to operate at current densities that produce < 0.3 W/cm2

. 

The aluminum heat exchanger was tested with the cooling plates inserted into the heat exchanger without 

any vacuum grease to fill the clearance space between each cooling plate and the walls of the heat 

exchanger slot. It was recognized that from a heat transfer perspective, this is a non-ideal situation. The 

heat exchanger was also tested with the slots filled with a vacuum grease to improve the thermal contact 

between the cooling plates and the heat exchanger. Figure 21 plots the average plate temperature for each 

of the four cooling plates at each of the power levels tested. Figure 21 plots both the results from the test 

done without grease as well as the test done with the vacuum grease. The results show that the vacuum 

grease substantially improves the heat transfer from the cooling plates to the heat exchanger because 

when the grease is used, the average plate temperature for all the plates is about 20° cooler than the case 

where no grease was used. In addition, the uniformity in performance between each of the four plates is 

much better with the grease than without.

Stainless Steel Heat Exchanger Test Results

The stainless steel heat exchanger shown in Figures 5 and 7 was tested in the heat exchanger vacuum 

chamber in the same manner that the aluminum heat exchanger was tested. The electrical power applied 

to the four cooling plates was varied from 2.5 to 22.5 W per plate. Figure 22 plots the average plate 

temperature for each of the four cooling plates at each of the power levels tested. Figure 22 plots both the 

results from the test done without grease as well as the test done with the vacuum grease. The results 

show that the vacuum grease did not substantially improve the heat transfer from the cooling plates to the 

heat exchanger as was the case with the aluminunm heat exchanger. The grease did improve the heat 

transfer by about 3°. In addition, the grease did not improve the uniformity in performance between each 

of the four plates.

Figure 21.—Aluminum heat exchanger average plate temperature.
NASA/TM—2010-216892 14

Figure 22.—Stainless steel heat exchanger average plate temperature

Figure 23.—Copper heat exchanger average plate temperature.

Copper Heat Exchanger Test Results

The copper heat exchanger shown in Figures 5 and 7 was tested in the heat exchanger vacuum 

chamber in the same manner that the aluminum and stainless steel heat exchangers were tested. The 

copper heat exchanger was also tested with a silver filled vacuum grease to see if the silver additive 

improved the thermal performance. The electrical power applied to the four cooling plates was varied 

from 2.5 to 22.5 W per plate. Figure 23 plots the average plate temperature for each of the four cooling 

plates at each of the power levels tested. Figure 23 plots both the results from the test done without grease 

as well as the test done with the two different vacuum greases. The results show that the vacuum grease 

did substantially improve the heat transfer from the cooling plates to the heat exchanger as was the case 

with the aluminunm heat exchanger. Both greases did improve the heat transfer by about 10°. In addition, 

the grease did improve the uniformity in performance between each of the four plates. The silver-filled 
NASA/TM—2010-216892 15

grease did perform slightly better than the non-filled grease. Based on this data, the grease used on the 

single-sided heat exchangers was the silver-filled grease.

Plastic/Aluminum Heat Exchanger Test Results

The plastic/aluminum heat exchanger shown in Figures 8, 9, and 10 was tested in the heat exchanger 

vacuum chamber in the same manner that the aluminum, stainless steel, and copper heat exchangers were 

tested. The plastic/aluminum heat exchanger was tested with a silver filled vacuum grease. The electrical 

power applied to the four cooling plates was varied from 2.5 to 22.5 W per plate. The test without the 

grease was run only up to 7.5 W per plate because the cooling plates were close to their maximum 

temperature. The test with the grease had power levels up to 22.5 W per plate. Figure 24 plots the average 

plate temperature for each of the four cooling plates at each of the power levels tested. Figure 24 plots 

both the results from the test done without grease as well as with the silver-filled grease. The results show 

that the vacuum grease did substantially improve the heat transfer from the cooling plates to the heat 

exchanger as was the case with the aluminunm and copper heat exchanger. The grease did lower the 

temperature of the cooling plates by over 30°. In addition, the grease did improve the uniformity in 

performance between each of the four plates. 

Aluminum, Stainless Steel, Copper, Plastic/Aluminum Heat Exchanger Comparison

The results from the aluminum, stainless steel, copper and plastic/aluminum heat exchanger tests run 

with grease (silver grease in the case of the copper and plastic/aluminum heat exchangers) are shown 

side-by-side in Figure 25 for comparison purposes. Figure 25 shows that the aluminum and copper heat 

exchangers make the cooling plates operate at 20° to 35° lower temperature. The thermal conductivity of 

the aluminum and copper metals are an order of magnitude greater than the stainless and the plastic, 

which is the likely reason for the superior performance. The uniformity of the plates in either the 

aluminum or copper heat exchangers are also much better than when the plates are in the plastic or 

stainless steel heat exchangers.

Figure 24.—Plastic/aluminum heat exchanger average plate 

temperature.
NASA/TM—2010-216892 16

Figure 25.—Heat exchanger average temperature comparison.

Figure 26.—Single-sided plastic/aluminum heat exchanger 

average temperature.

Single-Sided Plastic/Aluminum Heat Exchanger Test Results

The heat exchanger and cooling plates shown in Figures 11, 12 and 13 were designed to be integrated 

with a fuel cell stack. Unlike the previous heat exchangers tested, this heat exchanger attaches to the 

cooling plates only on one side of the cooling plates. This test verified that the heat exchanger and cooling 

plates would provide satisfactory cooling of the fuel cell stack since at all but the highest power levels the 

cooling plates were less than 80 °C (the operating temperature of the fuel cell stack). The heat exchanger 

and cooling plates were tested in the heat exchanger vacuum chamber in the same manner that the other

heat exchangers were tested. The plastic/aluminum heat exchanger was tested with the silver filled 

vacuum grease. The electrical power applied to the four cooling plates was varied from 7.5 to 29.5 W per 

plate, which equates to 0.1 to 0.4 W/cm2

. Figure 26 plots the average plate temperature for each of the 

four cooling plates at each of the power levels tested. The results showed very good cooling and uniform 

performance among the four plates, even at the high power levels.
NASA/TM—2010-216892 17

Anodized Aluminum Heat Exchanger Test Results

An anodized aluminum heat exchanger was designed to interface with the single-sided cooling plates. 

The comparison between the performance of the aluminum and plastic/aluminum heat exchangers shown

in Figure 25 showed that the aluminum had much better heat transfer performance. Since uncoated 

aluminum would electrically short the different cooling plates in a fuel cell stack, the heat exchanger was 

coated with an electrically nonconductive anodized coating. The heat exchanger and cooling plates were 

tested in the heat exchanger vacuum chamber in the same manner that the other heat exchangers were 

tested. The anodized aluminum heat exchanger was tested with the silver filled vacuum grease. The 

electrical power applied to the four cooling plates was varied from 7.5 to 41.5 W per plate, which equates 

to 0.1 to 0.55 W/cm2

. Figure 27 plots the average plate temperature for each of the four cooling plates at 

each of the power levels tested. The results showed excellent cooling and uniform performance among the 

four plates, even at the high power levels.

Single-Sided Heat Exchanger Comparison

Figure 28 shows the comparison of the two single-sided heat exchangers that used the same cooling 

plates. The anodized aluminum heat exchanger removed the heat from the cooling plates much more 

effectively than the plastic/aluminum heat exchanger. The applied heat was increased to 41.5 W/cm2 for 

the anodized aluminum heat exchanger, but could only be increased to 29.5 W/cm2 for the 

plastic/aluminum heat exchanger. Even at 41.5 W/cm2

, the temperature of the cooling plates in the 

anodized aluminum heat exchanger were over 20 °C cooler. The anodized aluminum heat exchanger 

allows excellent heat transfer while being electrically non-conductive.

Figure 27.—Anodized aluminum heat exchanger average temperature.
NASA/TM—2010-216892 18

Figure 28.—Single-sided heat exchanger average temperature comparison.

Figure 29.—Average plate temperature versus flow rate for the anodized heat exchanger.

Anodized Aluminum Heat Exchanger Temperature Versus Flow Rate

The anodized aluminum heat exchanger was tested at different coolant flow rates. At each flow rate 

the power level was varied from 7.5 to 41.5 W per plate. Figure 29 shows the results from the variation in 

flow rate. As the flow rate was increased, the average temperature of the cooling plates decreased. At 

higher flow rates the temperature of the cooling plates was not affected by further increases in the coolant 

flow rate. The data from this test indicates that the cooling plates can be kept within the 60 to 80 °C 

operating range of a fuel cell stack by varying the flow rate between 0 and 250 ml/min. At 80 °C the 

controlling flow rate range is 0 to about 100 ml/min.
NASA/TM—2010-216892 19

Conclusions

The efforts to develop a passive fuel cell thermal management heat exchanger have lead to the 

following conclusions:

1) A passive interface heat exchanger can be fabricated that is capable of removing the heat from 

cooling plates.

2)The best materials for the heat exchanger are more thermally conductive materials such as 

aluminum or copper, but the materials must also not electrically short the individual cooling plates. 

Anodized aluminum was the best material tested.

3) Vacuum grease between the cooling plates and the walls of the heat exchanger grooves 

substantially improves the ability of the heat exchanger to transfer heat. The vacuum grease also improves 

the performance uniformity between the different cooling plates. The silver-filled grease is slightly better

than the non-silver-filled grease.

4)Controlling the flow rate through the heat exchanger will be effective at maintaining the cooling 

plate temperature within the operating range of a fuel cell stack.

References

1. Kenneth A. Burke, “Advanced Thermal Management Materials for NASA Exploration Missions,”

NASA/TM—2009-206908, AIAA–2009–5795, presented at AIAA 7th International Energy 

Conversion Engineering Conference, August 2–5 2009, Denver, CO.

2. Kenneth A. Burke, “Advanced Fuel Cell System Thermal Management for NASA Exploration 

Missions,” NASA/TM—2008-215426, AIAA–2008–5795, presented at AIAA 6th International 

Energy Conversion Engineering Conference, Jul. 28–30, 2008, Cleveland, OH.

3. William E. Simon and Donald L. Nored, “Manned Spacecraft Electrical Power Systems,” Proceeding 

of the IEEE, Vol. 75, No. 3, Mar. 1987.

4. “Thermal properties of Metals,” ASM Material Data Series, ASM International, ISBN: 0–87170–

768–3, Dec. 2002.

5. D5506 Preliminary Product Data Sheet, revised Dec. 18, 2005, Cool Polymers Inc., 333 Strawberry 

Field Road, Warwick, RI 02886.
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5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Burke, Kenneth, A.; Jakupca, Ian, J.; Colozza, Anthony, J. 

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

WBS 038957.04.06.02.02.03 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

Cleveland, Ohio 44135-3191 

8. PERFORMING ORGANIZATION

 REPORT NUMBER

E-17471 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

Washington, DC 20546-0001 

10. SPONSORING/MONITOR'S

 ACRONYM(S)

NASA 

11. SPONSORING/MONITORING

 REPORT NUMBER

NASA/TM-2010-216892 

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited 

Subject Categories: 15, 20, and 44 

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

This publication is available from the NASA Center for AeroSpace Information, 443-757-5802

13. SUPPLEMENTARY NOTES

14. ABSTRACT

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the 

reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction 

within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell 

stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system 

which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly 

thermally conductive cooling plates that could conduct the heat, provide a sufficiently uniform temperature heat sink for each cell of the fuel 

cell stack, and be substantially lighter than the conventional thermal management approach. Tests were run with different materials to 

evaluate the design approach to a heat exchanger that could interface with the edges of the passive cooling plates. Measurements were made 

during fuel cell operation to determine the temperature of individual cooling plates and also to determine the temperature uniformity from 

one cooling plate to another. 

15. SUBJECT TERMS

Fuel cells; Electrochemical cells; Space propulsion; Energy conversion 

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

 ABSTRACT

UU 

18. NUMBER

 OF 

 PAGES

25 

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email:help@sti.nasa.gov) 

a. REPORT

U 

b. ABSTRACT

U 

c. THIS 

PAGE

U 

19b. TELEPHONE NUMBER (include area code)

443-757-5802 

Standard Form 298 (Rev. 8-98)

Prescribed by ANSI Std. Z39-18