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A0704
Ad anced solu ions o imp o e he wa e managemen
in elec ochemical hyd ogen comp esso s
Giuseppe Sdanghi* (1), Ma An a Diop (1), Jé ôme Dille (1), Mo i z B anco (2),
Thomas P ou é (3), Sophie Didie jean (1), Gael Ma anzana (1)
(1) LEMTA, Uni e si é de Lo aine, CNRS, 54500 Vandœu e-lès-Nancy/F ance;
(2) ESA, ESTEC, 2200 AG, Noo dwijk/ he Ne he lands;
(3) CEA-IRIG, DSBT, 38000, G enoble/F ance;
*Con ac co esponding au ho s: www.EFCF.com/Con ac Reques
Abs ac
Elec ochemical hyd ogen comp esso s (EHCs) ha e se e al ad an ages o e
mechanical comp esso s: hey a e ib a ion and noise ee and can be e y cos e ec i e.
Al hough sui able o applica ions in which low and mode a e p essu es a e equi ed, EHCs
ha e one majo d awback: he wa e managemen . To achie e good pe o mance, he
polyme ic memb ane mus be op imally humidi ied. Wi hou adequa e humidi ica ion, he
ope a ing condi ions can damage he memb ane, a ec ing o e all pe o mance and
e iciency
In his wo k, we p esen an EHC sys em in which he wa e managemen is con olled by
a passi e coun e cu en memb ane wa e exchange . This de ice allows d ying he
p oduced hyd ogen low while simul aneously humidi ying he low-p essu e hyd ogen ed o
he comp esso . This highly lexible d ying sys em can achie e a dew poin empe a u e o
less han −30 °C. A d ye s uc u ed in his way a oids con en ional d ying me hods such
as TSA o PSA cycles, which a e e y demanding in e ms o powe and hea ejec ion. A
he same ime, i also a oids he use o con en ional hyd ogen humidi ica ion me hods,
which equi e expensi e auxilia y equipmen .
Se e al memb ane elec ode assemblies (MEAs) ha e been used in his s udy and he
e ec o hei p ope ies on he comp ession pe o mance has been in es iga ed. Cu en
densi ies up o 4 A cm-2 we e achie ed a low ol age and low empe a u e (up o 0.4 V and
35 °C), wi h pumped lows g ea e han 0.8 mg s-1 [1]. The highes e iciencies (> 60) we e
achie ed in a ange o low ol ages and cu en densi ies, bu he e iciency o he EHC
dec eased d ama ically as he ol age was inc eased. Howe e , his condi ion is essen ial
o achie e high cu en densi ies, which a e con e ed in o high comp essed hyd ogen lows.
An op imum mus he e o e be ound be ween pe o mance and cos .
Ne e heless, he lexibili y o his comp esso , wi h i s wide ange o low a es and o al
absence o ib a ion, should be highligh ed. Indeed, such a sys em is sui able o ae ospace
applica ions (e.g., o p oduce cold ene gy in a Joule-Thomson c yocoole ), bu also o
e es ial hyd ogen applica ions, such as injec ion in o gas pipelines o s o age in
unde g ound sal ca e ns.
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In oduc ion
Bo h ecip oca ing and cen i ugal hyd ogen comp esso s a e e y ma u e echnologies,
and a e widely used wo ldwide o comp ess hyd ogen. Howe e , hey a e cha ac e ized by
e y high capi al and ope a ing cos s, and a numbe o incon eniences such as noise,
ib a ion and la ge size [1].
Elec ochemical comp esso s (EHCs) appea o be an a ac i e al e na i e. They a e non-
mechanical comp esso s, which means no noise o ib a ion, as well as low ope a ing cos s
and high e iciency, since comp ession is iso he mal [2]. In addi ion, hey a e also e y
compac , and ha e p o en o be economically ad an ageous o p essu es up o 120 ba
[3]. The highe he cu en applied o an EHC, he mo e high-p essu e hyd ogen is p oduced.
Howe e , in o de o ake ad an age o la ge lows, a signi ican amoun o ene gy mus be
consumed, wi h a consequen d op in e iciency.
EHC has one majo d awback namely he wa e managemen [4]. To achie e good
pe o mance, EHC equi es a ce ain amoun o ex e nal wa e o ensu e adequa e hyd a ion
o he memb ane. Two main mechanisms egula e he wa e con en wi hin he MEA, i.e.,
he elec o-osmo ic mig a ion and he back-di usion [5]. In low p essu e applica ions, wa e
anspo om he anode o he ca hode p edomina es, due o he low wa e con en esul ing
om back-di usion compa ed o elec o-osmo ic mig a ion [6]. Pa icula ly a high cu en
densi ies, low amoun s o liquid wa e esul ing om back-di usion can be insu icien o
humidi y he memb ane, leading o d ying. On he o he hand, p olonged ope a ion can esul
in wa e condensa ion in he low-p essu e compa men , leading o looding [7]. Bo h
si ua ions lead o a d ama ic educ ion in pe o mance. This demons a es he impo ance
o wa e managemen in EHC, whe e wa e balance is necessa y and mus be ca e ully
achie ed.
In EHCs, wa e is gene ally supplied by an ex e nal sou ce, humi ying he hyd ogen
supplied on he low-p essu e anode side [8]. Humidi ica ion o he memb ane is achie ed
du ing ope a ion by elec o-osmo ic mig a ion. Liquid wa e can also be supplied o he
ca hode compa men , o p omo e he humidi ica ion o he memb ane by di usion and o
compensa e o he elec o-osmo ic d ag, hus achie ing balanced wa e anspo
h oughou he EHC. This solu ion ce ainly looks p omising, bu a p essu e- esis an pump
mus be used o eci cula e high-p essu e liquid wa e in o he ca hode compa men ,
inc easing he cos .
The aim o his s udy was o de elop an EHC in conjunc ion wi h i s wa e managemen
sys em o eed a Joule-Thomson c yocoole o ae ospace applica ions. The con en ional
EHC a chi ec u es desc ibed abo e a e no easible in his con ex due o olume and weigh
cons ain s. The e o e, we ha e de eloped a non-con en ional EHC a chi ec u e in
conjunc ion wi h an ad anced wa e managemen sys em, wi h he aim o p oducing high-
p essu e hyd ogen a a e y low dew poin empe a u e.
1. Scien i ic App oach
This s udy ocused on es ing he easibili y o an EHC wi h an ad anced wa e
managemen sys em, and iden i ying he mos sui able assembly ma e ials ha would gi e
he bes pe o mance h ough an expe imen al app oach. In addi ion o he need o
minimizing he ohmic losses, a majo challenge in EHC is o limi hyd ogen pe mea ion
h ough he memb ane, which is la ge when he p essu e di e ence be ween he ca hodic
and anodic compa men s is inc eased.
The de eloped sys em has wo impo an inno a i e ea u es: (i) he EHC includes an
ad anced wa e managemen sys em capable o p e en ing wa e condensa ion a he low
anodic compa men ; (ii) e y d y high-p essu e hyd ogen is p oduced by using a wa e
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memb ane d ye . To a oid he p esence o liquid wa e on he anode side due o he wa e
condensa ion (which can occu especially du ing ansien ope a ion), a empe a u e
g adien is imposed be ween he low- and he high-p essu e compa men [9]. The use o a
wa e memb ane exchange in conjunc ion wi h an EHC is a ai ly new concep . Wa e
managemen using a passi e memb ane exchange o e s se e al ad an ages o e
al e na i e me hods (cyclonic sepa a ion, cold ap and molecula sie e), pa icula ly in
e ms o weigh and ene gy consump ion. The p inciple consis s o adso bing he o e low
o wa e om he humidi ied low a high p essu e owa ds he low p essu e one, which has
a lowe ela i e humidi y. The passi e wa e memb ane exchange , which allows wa e o
be ans e ed by simple pe mea ion (since he e is no powe supply) enables he hyd ogen
low supplied o he anode compa men o he EHC o be humidi ied and he high-p essu e
hyd ogen low p oduced o be d ied. A closed loop can hus be c ea ed.
2. Expe imen s
Ma e ials
Ti anium low ield pla e we e used on bo h anode and ca hode side. Pin- ype channels
we e machined on o he anode pla e and on an ac i e su ace o 25 cm2. On he anode side,
po ous pla inum-coa ed sin e ed i anium wi h an a e aged po e size o 5µm and hickness
o 1mm was used as po ous ans e laye (PTL). A Sig ace 28 BA ca bon GDL equipped
wi h an MPL was used be ween he Ti-PTL laye and he MEA.
Se e al MEA we e used in he p esen s udy: Na ion XL (≈ 27.5 µm hick), Na ion™ HP
(≈ 22.5 µm hick) and an MEA supplied by Hypla wi h a hyd ophobic ea men by he
addi ion o PTFE addi i es on he anode side (≈ 30 µm hick). The ca alys loading o all he
MEAs was 0.3 mgP cm-2. The ac i e su ace o hese MEAs was 25 cm2. On he ca hode
side, a Sig ace 28 AA laye was used as GDL. Two laye s-PTLs we e used o collec wa e
by capilla y ac ion: a i s laye consis ing o P -coa ed Ti el s (GLD20 wi h an a e age po e
size o 40 μm), and a second laye made o deployed-Ti wi h a highe po e size (≈ 0.5 mm).
Rega ding he wa e memb ane exchange , an uncoa ed Ti-PTL was used a he low-
p essu e compa men , while ca bon Sig ace 28 AA laye s we e used as GDL a he high-
p essu e compa men . As no chemical eac ion occu ed in he wa e exchange , a
Na ion™ 212 memb ane was used in place o a MEA.
Expe imen al Se up
The expe imen al se up used in he p esen s udy consis ed o an EHC and a wa e
memb ane exchange in se ies. Downs eam o he wa e memb ane exchange , a as -
esponse Dew Poin Hyg ome e (Easidew EA2 Michell Ins umen s) allowed he dew poin
empe a u e o he pumped hyd ogen low o be measu ed, while a back-p essu e egula o
(BROOKS SLA5820S) was kep closed o allow he p essu e o inc ease p og essi ely, and
opened once he desi ed p essu e was eached. A BROOKS SLA5850S lowme e was
used downs eam o he p essu e egula o o measu e he low o hyd ogen e u ning o he
low-p essu e compa men o he wa e memb ane exchange and deduce he a adic
e iciency.
To a oid wa e condensa ion on he anode compa men , a empe a u e g adien was
es ablished o e he cell, wi h he anode wa me han he ca hode compa men . The
empe a u e o each compa men was con olled independen ly by wo he mal ba hs using
P 100 senso s. In addi ion, gas lines we e o e hea ed o p e en wa e condensa ion.
P essu e ansduce s we e used in bo h he anode and ca hode compa men s (RS 136-
5045). An ITECH IT-M3903D-10-340 high-powe DC powe supply was used o powe he
EHC. Da a we e au oma ically acqui ed using an RS 485 in e ace and he LabVIEW®
so wa e.
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i-V cu es we e eco ded by g adually inc easing he ol age o e a limi ed, op imized
ol age ange o each memb ane (0.15-0.4 V, wi h a s ep o 0.05 V). Se e al a e age
empe a u es be ween 20 and 55 °C we e es ed. A empe a u e g adien o 10 °C was also
applied be ween he low- and high-p essu e compa men s, he o me being wa me han
he la e o a oid wa e condensa ion. All expe imen s we e pe o med wi h a hyd ogen
p essu e o 100 ba a he ca hode side.
Ope a ing p o ocol
Liquid wa e was i s ly in oduced in o he sys em a he ca hode compa men o he
comp esso cell, o humidi y he Ti el , and hence he memb ane. A hyd ogen low (≈ 6 NL
h-1) was supplied o he memb ane exchange (whe e i was humi ied), and hence o he
comp esso cell. A highly humid high-p essu e hyd ogen low (sa u a ed a he empe a u e
o he high-p essu e pla e) was p oduced while he sys em was p o ided wi h elec ical
powe . The humidi ied high-p essu e hyd ogen low passed h ough he memb ane
exchange . Wa e di used om he high-p essu e compa men o he low-p essu e
compa men , humidi ying he incoming low-p essu e and d y hyd ogen low in coun e -
cu en . As a esul , humidi ied low-p essu e hyd ogen was p og essi ely ed in o he EHC.
3. Resul s
The pola iza ion i-V cu es a di e en ope a ing empe a u es ob ained when using a
MEA wi h PTFE addi i es on he anode side a e shown in Figu e 1a. The ange o
in es iga ed ol ages was be ween 0.15 and 0.4 V, due o he occu ence o a limi ing cu en
densi y, especially a lowe empe a u es, o ol ages highe han 0.4 V.
Figu e 1 - a) i-V cu es eco ded in he ange o ol ages 0.1-0.4 V using an MEA wi h a hyd ophobic
ea men on he anode side, a 100 ba unde se e al empe a u e condi ions; b) Pumped hyd ogen low
ob ained a 100 MPa in he EHC equipped wi h he same MEA as a unc ion o he powe supplied
The beha io o he i-V cu es was ound o be almos linea in he low ol ages ange
(< 0.25 V), whe eas he cu en densi y inc eased sha ply, app oaching a limi ing alue, a
highe ol ages. This beha io has al eady been obse ed in ou p e ious wo k [5], and is
ela ed o he wa e anspo ac oss he memb ane. Indeed, he o al esis ance o he EHC
inc eases when inc easing he cu en densi y, as a consequence o he educ ion in he
a) b)
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memb ane p o on conduc i i y esul ing om he memb ane dehyd a ion. This phenomenon
is pa icula ly p onounced a low empe a u es.
A signi ican inc ease in cu en densi y was obse ed when inc easing he ope a ing
empe a u e o a gi en ol age. A cu en densi y o app oxima ely 2.4 A cm-2 was ob ained
a an a e age empe a u e o 55 °C and a 0.4 V, while almos hal he alue, 1.2 A cm-2,
was ob ained a abou 20 °C a he same ol age applied. Figu e 1b shows he pumped
hyd ogen low a e ob ained as a unc ion o he powe supplied. The highes hyd ogen low
a 100 ba was ob ained a an a e age empe a u e o 55 °C (23 NL h-1) while supplying
abou 22 W o elec ical powe . App oxima ely 19 NL h-1 o hyd ogen a 100 ba was
p oduced when supplying 14 W a 55 °C, whe eas a lowe alue, 11.7 NL h-1, was ob ained
when supplying he same amoun o elec ical powe bu a 20 °C. This means ha i was
possible o inc ease by abou 62% he amoun o hyd ogen comp essed a 100 ba in an
EHC equipped wi h he PTFE- ea ed MEA when aising he a e aged ope a ing
empe a u e by 35 °C.
The imp o emen in pe o mance ob ained when inc easing he ope a ing empe a u e
can be explained by he dec ease in he ohmic esis ance, a well-known cha ac e is ic. As
e idence, he ohmic esis ance calcula ed a 20 °C (as he slope o he i-V cu e) was equal
o 0.27 Ω cm-2, and dec eased by abou 70% and down o 0.158 Ω cm-2 when he
empe a u e was inc eased o 55 °C. The main e ec o he empe a u e inc ease is he
imp o emen o he p o on conduc i i y o he memb ane. The highe he p o on conduc i i y
he lowe he ohmic esis ance.
Figu e 1a also shows a sligh imp o emen in he elec ochemical pe o mance ob ained
when applying a he mal g adien o 10°C be ween he anodic and he ca hodic
compa men s, compa ed o he esul s ob ained when keeping bo h compa men s a he
same empe a u e. When he anode is wa me han he ca hode side, wa e condensa ion
can be p e en ed, as p e iously discussed. This phenomenon is mo e p onounced in
dynamic egimes and a he s a o expe imen s. Howe e , he applica ion o a he mal
g adien only gi es a small imp o emen in pe o mance unde s eady-s a e condi ions.
Figu e 1b also shows he compa ison be ween he measu ed hyd ogen lows p oduced
a 100 ba and he heo e ical ones calcula ed in acco dance wi h Fa aday's Law, as a
unc ion o he powe applied. We conside ed ha he di e ence be ween hese wo amoun s
could be used as an empi ical basis o e alua e he hyd ogen pe mea ion a e ac oss he
memb ane. In e es ingly, i was ound ha he pe mea ion a e was highe a low
empe a u es (a ound 20°C), while i ended o become negligible a highe empe a u es.
A 60 °C, no di e ence was obse ed be ween he measu ed and he heo e ical hyd ogen
lows. To explain his end, we conside ed he e ec s o bo h he assembly componen s
and he memb ane's hyd a ion le el. Fi s , we placed a Mic opo ous Laye (MPL) be ween
he PTL and he MEA a he low-p essu e compa men . The elimina ion o pe mea ion a
high empe a u es can be explained by he ac ha he memb ane is well-suppo ed by
small po es when an MPL is used, esul ing in a la , unde o med memb ane. Con e sely,
when he memb ane is suppo ed by la ge po es, as wi h a PTL alone, i expe iences ensile
s ess due o p essu e and unde goes a educ ion in hickness. This esul s in g ea e
hyd ogen pe meabili y. Con e sely, he inc eased hyd ogen pe mea ion obse ed a low
empe a u es was p obably due o he highe hyd a ion le el o he memb ane. Gas
pe mea ion o p o on exchange memb anes is pa icula ly enhanced when hey a e ully
hyd a ed. In ac , hyd ogen pe meabili y is app oxima ely en imes g ea e han in he solid
phase [10]. Fu he mo e, acco ding o he wa e so p ion measu emen s ound in he
li e a u e [11,12], he wa e con en o he memb ane is gene ally highe a low empe a u es.
The hyd ophobic ea men a he anode side has p obably con ibu ed o keeping he
memb ane well hyd a ed, especially a low empe a u es. Indeed, he memb ane hyd a ion
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occu ed by di usion om he hyd ophilic ca hode compa men o he hyd ophobic anode
compa men du ing he ansien egime, which could ha e acili a ed he pe mea ion o
hyd ogen ac oss he memb ane in he same sense.
To be e e alua e he pe o mance o he MEA wi h a PTFE- ea ed anode, we compa ed
he i-V ob ained a an a e age empe a u e o 35 °C wi h hose o wo o he MEAs, consis ing
o Na ion XL (≈ 27.5 µm) and Na ion HP (≈ 22.5 µm) memb anes, ha ing he same ca alys
loading bu wi hou PTFE ea men on he anode side (Figu e 2).
Figu e 2 - Compa ison be ween h ee di e en MEAs es ed wi h he anode empe a u e a 40 °C and he
ca hode empe a u e a 30 °C
The pe o mances achie ed when using he Na ion HP MEA we e supe io o hose
ob ained using bo h a Na ion XL and a PTFE- ea ed MEAs. As e idence, a cu en densi y
o 2.7 A cm-2 was measu ed when applying a ol age o 0.4 V, which is 50% highe han ha
ob ained when using a PTFE- ea ed MEA (1.8 A cm-2) and 26% highe han ha measu ed
wi h a Na ion XL MEA (a ound 2 A cm-2). This imp o emen was due o bo h he lowe
hickness o he memb ane and he highe Ion Exchange Capaci y (IEC) o Na ion HP. In
ac , he hinne hickness o Na ion HP esul ed in a lowe ohmic esis ance. Mo eo e , he
IEC o Na ion HP (≈ 1.08 meq g-1) is highe compa ed o ha o Na ion XL (≈ 0.9 meq g-1),
esul ing in an enhanced ion exchange in he memb ane, and he e o e a highe p o onic
conduc i i y a he same empe a u e. A u he conside a ion o ake in o accoun is ha he
wa e managemen me hod used in his s udy is be e sui ed o he use o hin memb anes.
Using hin memb anes acili a es he ans e o wa e om he high-p essu e o he low-
p essu e compa men , esul ing in he mo e e icien humidi ica ion o he memb ane.
Due o he imp o ed pe o mance achie ed wi h a Na ion HP MEA, a long- e m
expe imen al es was conduc ed o e alua e comp ession pe o mance and iden i y
ope a ing issues. Figu e 3 shows he beha io o he ca hode p essu e, cu en densi y, and
dew poin empe a u e o e a pe iod o app oxima ely 270 ope a ing hou s (abou 11 days)
when applying a ol age o 0.2 V.
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Figu e 3 – Cu en densi y (blue), ca hode p essu e ( ed) and dew poin empe a u e (black) beha iou in a
270 hou s expe imen (anode empe a u e = 40 °C, ca hode empe a u e = 30 °C), when using a Na ion HP
MEA and when applying 0.2 V
Th oughou he en i e expe imen , he ca hode p essu e emained s able a 100 ba . The
expe imen was conduc ed by applying a empe a u e g adien be ween he 40°C anode
compa men and he 30°C ca hode compa men . Expe imen s pe o med a highe
empe a u es esul ed in a collapse o pe o mance a e a ew hou s o ope a ion. This
d ama ic loss o pe o mance was a ibu ed o he mechanical p ope ies o he memb anes,
which we e a ec ed by he combined e ec o he ela i ely high empe a u e and he high-
p essu e g adien (100 ba ) ac oss he cell. By keeping an a e age empe a u e o 35°C
o e he cell, no memb ane ailu e was obse ed du ing 10 days. The cu en densi y also
emained almos s able a an a e age alue o abou 1.5 A cm-2 when applying 0.2 V. A e
10 days o ope a ion, a sligh dec ease o he cu en densi y was obse ed, due o a wa e
managemen issue, as e idenced by he beha io o he dew poin empe a u e.
Figu e 3 also shows he pe o mance o he wa e memb ane exchange used in he
p esen s udy, whose ole was bo h o humidi y he low-p essu e hyd ogen low supplied o
he EHC and o d y ou he p oduced high-p essu e hyd ogen low. Using a passi e wa e
exchange as desc ibed in he Expe imen al Sec ion, a dew poin empe a u e as low as
-29 °C was achie ed, co esponding o a ela i e humidi y o abou 1.5% a 35 °C.
Ne e heless, he dew poin empe a u e inc eased d ama ically o 60°C a e 11 hou s o
ope a ion, e ealing issues in he wa e managemen and he p esence o liquid wa e
d ople s inside he hyg ome e , hus a ec ing i s p ope unc ioning. Since i was no longe
possible o eco d da a, he expe imen was s opped.
In his s udy, only he easibili y o he wa e memb ane exchange was es ed. The dew
poin empe a u es achie ed con i med ha such a de ice can be a aluable ool o d y
highly humid lows o hyd ogen. E en lowe dew poin s could be achie ed and he du abili y
o he de ice imp o ed, by inc easing he po osi y o he di usion laye s, op imizing he
exchange su ace a ea o by using di e en channel con igu a ions o imp o e he wa e
ans e , e.g., using in e digi a ed channels. In iew o hese encou aging pe spec i es, we
sized a s ack o EHC o be used in ae ospace applica ions oge he wi h i s wa e
managemen sys em consis ing o a wa e memb ane d ye . Figu e 4a shows he esul s o
he sizing o a o al hyd ogen low o a ound 400 NL h-1, which is conside ed ideal o use
in a Joule-Thomson c yocoole .
EFCF 2025: Low-Temp. Fuel Cells, Elec olyse s & H2 P ocessing 1 – 4 July 2025, Luce ne Swi ze land
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Figu e 4 – a) Sizing o an EHC s ack equipped wi h a Na ion HP MEA o di e en applied ol ages (T
anode = 40 °C, T ca hode = 30 °C) o p oduce 400 NL h-1 o hyd ogen a 100 ba ; b) E iciency o an EHC
equipped wi h a Na ion HP MEA a di e en ope a ing condi ions
Acco ding o Fa aday’s law, he highe he cu en applied, he highe he hyd ogen low
p oduced by a single EHC cell. This means ha in o de o p oduce a gi en o al low o
high-p essu e hyd ogen, he numbe o cells equi ed in he s ack is low when high powe is
applied, while a highe numbe o cells mus be used when he applied powe is ela i ely
low. As shown in Figu e 4a, a ound 12 cells ha e o be used o p oduce 400 NL h-1 o
hyd ogen a 100 ba a an a e age empe a u e o 35 °C and a 400 W, while o p oduce he
same amoun o hyd ogen bu applying 150 W, a 3 imes la ge EHC wi h 38 cells needs o
be used. A ade-o be ween ene gy consump ion and size is he e o e necessa y o ind an
op imum, which is o apply a ela i ely low powe o an EHC o a e age size.
Figu e 4b also con i ms he need o a ade-o , by showing he beha io o he o al
e iciency o an EHC as a unc ion o he pumped hyd ogen low. The e iciency o an EHC
can be exp essed as ollows:
𝜂 = 𝑊𝑡ℎ
𝑊𝑟𝑒𝑎𝑙
=𝑉𝑁𝑒𝑟𝑛𝑠𝑡
𝑉⋅𝐼 − 𝐼𝑙𝑜𝑠𝑠
𝐼
(1)
whe e VNe ns is he Ne ns ol age, V is he eal ol age applied o he EHC o comp ess
hyd ogen, I is he cu en densi y and Iloss is he cu en densi y de i ing om he hyd ogen
pe mea ion ac oss he memb ane.
The maximum e iciency o a ound 62% was achie ed when low hyd ogen lows we e
p oduced, i.e., a low cu en densi ies (hence, low applied powe ). I is wo h no ing ha he
e iciency o an EHC can be e en highe a e y low cu en densi ies, i.e., when a ol age
close o he Ne ns po en ial is applied. Howe e , hese ope a ing condi ions a e no o
p ac ical in e es as only a small amoun o hyd ogen is p oduced a low cu en densi ies.
The highes e iciencies we e achie ed when a pumped hyd ogen low o a ound 5 NL h-1
was p oduced. P oducing mo e hyd ogen a high p essu e means ha mo e powe has o
be supplied o he EHC, which con ibu es o he inc ease in o e ol ages and hence he
dec ease in e iciency. As shown in Figu e 4b, a signi ican loss o e iciency was ob ained
when 5- imes highe hyd ogen lows we e p oduced. Indeed, he EHC had an e iciency o
15% when p oducing a ound 25 NL h-1 o hyd ogen a 100 ba .
Conclusions
An inno a i e wa e managemen sys em o elec ochemical hyd ogen comp esso s
(EHC) has been de eloped in he p esen s udy. I consis s o p oducing d y hyd ogen a
a) b)
EFCF 2025: Low-Temp. Fuel Cells, Elec olyse s & H2 P ocessing 1 – 4 July 2025, Luce ne Swi ze land
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100 ba by ins alling a passi e wa e memb ane exchange downs eam o an EHC. This
wa e managemen sys em allowed achie ing dew poin s empe a u es o a ound -29 °C,
co esponding o a ela i e humidi y o abou 1.5% a 35°C.
The de eloped EHC had an uncon en ional a chi ec u e. A empe a u e di e ence was
applied be ween he anode and he ca hode compa men s o p e en wa e condensa ion
a he anode compa men and hus he looding o he ca aly ic si es. Unde he ope a ing
condi ions in es iga ed in his s udy, applying a he mal g adien o 10 °C ac oss he EHC
allowed sligh ly be e pe o mances o be ob ained han in he case o a uni o m
empe a u e h oughou he cell.
Se e al MEAs we e es ed: Na ion XL (≈ 27.5 µm hick), Na ion™ HP (≈ 22.5 µm hick)
and an MEA supplied by Hypla wi h a hyd ophobic ea men by he addi ion o PTFE
addi i es on he anode side (≈ 30 µm hick). The bes pe o mances we e ob ained when
using a Na ion HP MEA, which has bo h a lowe hickness and a highe Ion Exchange
Capaci y, allowing highe p o onic conduc i i ies, highe wa e ans e a es and hus a
lowe esis ance o be achie ed. As e idence, a cu en densi y o 2.7 A cm-2 was measu ed
when applying a ol age o 0.4 V, which is 50% highe han ha ob ained when using a
PTFE- ea ed MEA (1.8 A cm-2) and 26% highe han ha measu ed wi h a Na ion XL MEA
(a ound 2 A cm-2).
The highes e iciencies (> 60%) we e achie ed in a ange o low cu en densi ies and
ol ages close o he Ne ns po en ial, bu he e iciency o he EHC dec eased d ama ically
as he ol age was inc eased. Howe e , his condi ion is essen ial o achie e high cu en
densi ies, which a e con e ed in o high comp essed hyd ogen lows pe single cell, hus
in o a mo e compac and lexible sys em. An op imum mus he e o e be ound be ween
ene gy consump ion and capi al expendi u e. Ne e heless, he lexibili y o his comp esso ,
wi h i s wide ange o low a es and o al absence o ib a ion, should be highligh ed, being
sui able o bo h e es ial and ae ospace applica ions.
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