Open sorption systems, desiccant air- handling units ...lmora.free.fr/task38/pdf/matin/Motta.pdf ·...

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Open sorption systems, desiccant air-handling units – market status andnew developments

Mario [email protected]

Wednesday, 25th April 2007Workshop “Solar Air-Conditioning and Refrigeration”Aix Les Bains

TASK 38Solar Air-Conditioning and Refrigeration

Mario Motta – [email protected]

Basic process

Thermal driven cooling process

heat

chilled water

conditioned air

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backupheater

chiller

heat supply system chilled water

conditioned airbuilding/roomreturnair

supplyair

ambientair

exhaustair

bufferstorage

desi

ccan

t w

heel

heat

rec

over

y w

heel

DEC general scheme


� desiccant systems are used for direct air treatment

� they generally consist of a combination of sorptiveair dehumidification and evaporative cooling

� the potential to apply evaporative cooling is increased by air dehumidification

� a desiccant system replaces a conventional air handling unit to provide fresh air without using a conventional compression chiller

Desiccant and evaporative cooling systemsMarket available equipment

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� two major technologies exist:

� systems with desiccant rotors:desiccant rotors available in a broad range of sizes from several manufacturers; sorption material either silica gel or lithium-chloride; cycle adjustable to different climatic conditions

� systems using liquid desiccants:few systems in pilot plant operation; in almost all cases LiCl as desiccant material

Desiccant cooling systemsMarket available equipment


Basic process: direct evaporative cooling

0

4

8

12

16

20

24

28

32

36

40

0 2 4 6 8 10 12 14 16 18 20 22

humidity ratio [g/kg]

tem

pera

ture

[°C

]

ambientair

supplyair

4


0

4

8

12

16

20

24

28

32

36

40

0 2 4 6 8 10 12 14 16 18 20 22


tem

pera

ture

[°C

]

Indirect evaporative cooling

ambientair

supplyair


0

4

8

12

16

20

24

28

32

36

40

0 2 4 6 8 10 12 14 16 18 20 22


tem

pera

ture

[°C

]

Combined evaporative cooling

ambientair

supplyair

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Standard DEC process (e.g., Continental Europe)

humidifier cooling loads

supply air

backupheater

return air

dehumidifier wheel

heat recovery wheel

1 2 3 4 56

789101112


Standard DEC process for moderate climates(e.g., Centrale Europe)

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22

absolute Feuchte [g/kg]

Tem

pera

tur

[°C]

1

11

4

7

Befeuchter Kühl-lasten

ZU

Zusatz-wärme

AB

Entfeuchter WRG

1 2 3 4 56

789101112

AU

FO

2

3

8

9

10

Humidity ratio

Tem

pera

ture

[°C]

6


Desiccant wheels


enthalpy exchanger

dehumidifierrotor

heat recovery

ambient air

supply air

return air from building

exhaust air

driving heat

humidifiers

enthalpy exchanger (total heat exchanger) for pre-

dehumidification of ambient air in counter-flow to building return air

Modified scheme for humid climate(e.g., South Mediterrenean)

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10

20

30

40

50

60

70

80

90

100

4 6 8 10 12 14 16 18 20 22 24 26 28


tem

pera

ture

[°C

]

.

enthalpy exchanger

dehumidifierrotor

heat recovery

ambient air

supply air

return air from building

exhaust air

driving heat

humidifiers

Modified scheme for humid climate(e.g., South Mediterrenean)


humidifier

supplyair

returnair

dehumidifier heat recovery

heat

ambientair

exhaustair

chilledwater

chilledwater

combination of standard system with cooling coils for pre-dehumidification and temperature

control

Scheme for very humid climates(e.g., Asia)

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10

20

30

40

50

60

70

80

4 6 8 10 12 14 16 18 20 22 24 26 28


tem

pera

ture

[°C

]

.

humidifier

supplyair

returnair

dehumidifier heat recovery

heat

ambientair

exhaustair

chilledwater

chilledwater

Scheme for very humid climates(e.g., Asia)


ECOS - indirect Evaporative COoling counter-flow heat exchanger with Sorption

� Objective: high dehumidification and cooling

� simultaneous sorptive dehumidification and cooling processes

� return continuously humidified while passing through the heat exchanger: best use of enthalpy uptake for indirect adiabatic cooling

� regeneration is realized with heated ambient air

� periodical process two heat exchangers in order to realize a quasi-continuous operation

Zuluft

Aussen-luft

Fortluft

Regenerations-luft

Fortluft

AbluftSorptions-mittel

supplyair

returnair

ambientair

exhaustair

regenerationair

exhaustair

sorptionmaterial

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The ECOS process path

Dott. Mario Motta, Fraunhofer Institute for Solar Energy systems (ISE) – [email protected]

T-x-Diagram Ambient 35°C, 20 g/kg - r90 - PH

0

5

10

15

20

25

30

35

40

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25


Tem

pera

ture

[°C

]

Sorptive channel

Cooling channel

1

2

3

4

5

6

Sorpt ion materialSorpt ion materialSorpt ion materialAmbient air

Exhaust

Ambient air

Exhaust Supply air

Return air

Supply air

Return air

optionalopt ional

1

2 3

4

6

5

ECOS – advanced desiccant and

evaporative cooling


0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

absolute Feuchte [g/kg]

Tem

pera

tur

[°C]

.

Zuluft

Aussen-luft

Fortluft

AbluftSorptions-m aterial

optional

Fortluft

Regenerations-luft

ECOS – advanced desiccant and

evaporative cooling

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Complete system with two heat exchangers

A possible hydraulic design and operation sequence

sorption

desorptionactive

exhaust air

external air

supply air

return air

1

2 3

4 5

6

7 8

9 10

Phase 1:Top:cooled sorptive dehumidification Bottom:regeneration


Phase 2:Top:cooled sorptive dehumidification Bottom:pre-cooling

sorption

exhaust air

external air

supply air

return air

1

2 3

4 5

6

7 8

9 10



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Phase 3:Top:regeneration Bottom:cooled sorptive dehumidification

desorption

sorption

active

exhaust air

external air

supply air

return air

1

2 3

4 5

6

7 8

9 10




diluted solution

concentratedSolution

regeneration air

<= QR(driving heat)

=> QA(waste heat)

regenerator

absorber

process air

Principle of liquid sorption

� Open absorption

� Possibility to store energy through regenerated solution

� Possible shift between radiation availability and regeneration

� Pilot plants in Germany and Israel

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Advantage of liquid sorption

� the absorption process is cooled; thereby a higher dehumidification is possible using the same driving temperatures (typically 55 - 75 °C)

� the concentrated solution can be used as high-efficient storage; thereby a mismatch between regeneration (solar gains) and dehumidification (cooling loads) can be overcome

Thank you for your attention !!!


Conclusions

� Open cycles based on solid sorbents are particularly suitable for solar assisted air-conditioning system applications where a ventilation system (allair or hybrid distribution) is compulsory

� DEC’s using rotors still high extra costs but the market potential results significant for large capacity applications (>10.000 m3/h)

� Several new developments employing solid and liquid DEC. Could have high potential for small capacity applications.

Thank you for your attention !!!

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schwache Lösung

konzentrierteLösung

Regenerations-luft

⇐⇐⇐⇐ QH Antriebswärme

⇒⇒⇒⇒ QM Wärmeabgabe

Regenerator

Absorber

Prozessluft

Speicher

LiCl/water

Offene Systeme mit Flüssigsorption


Offene Systeme mit Flüssigsorption - Prinzip

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Prototyp eines Lüftungsgerätes mit Flüssigsorption

Lüftungsgerät mit indirekter Verdunstungskühlung un d sorptiver Entfeuchtung (Fa. Menerga)


Menerga System

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Sistema DEC per una biblioteca

� Sito: Mataro/Spagna

� Utente: Biblioteca pubblica

� Tipologia: Sistema DEC (12000 m3/h) con 105 m2 collettori ad aria e pre-riscaldamentoattraverso facciata fotovoltaica

� Utilizzo: Climatizzazione centro audiovisivi(2.120 m3)


Condizionamento sala seminariFriburgo (Germania)

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� Collettori solari ad ariacome unica fonte di calore: 100 m2

� Sistema DEC (10.200 m3/h) con rotore al gel silicato

� no sistema back-up

� Condizionamento sala seminari (piccola sala riunioni) presso l’edificio della camera di commercio di Friburgo/ Germania

� Sistema solare semplificato e semplice integrazione con l’impianto di

condizionamento

� no back-up, no serbatoio

� Schema promettente per edifici con alta correlazione tra carichi di condizionamento e radiazione solare

Condizionamento sala seminari


Funzionamento invernale

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Funzionamento estivo

Open sorption systems, desiccant air- handling units ...lmora.free.fr/task38/pdf/matin/Motta.pdf ·...

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