Renewable Energy Week, Brussels, Jan/Feb 2007 1

Hans-Martin Henning

Fraunhofer-Institut für Solare Energie-

systeme ISE, Freiburg/GERMANY

Solar Cooling and

Air-Conditioning

Renewable Energy Week, Brussels, Jan/Feb 2007 2

Overview

• Introduction

• Technologies

• Status, Examples

• Outlook

Renewable Energy Week, Brussels, Jan/Feb 2007 3

Introduction

• Introduction

• Technologies

• Status, Examples

• Outlook

Renewable Energy Week, Brussels, Jan/Feb 2007 4

World market for air-conditioning

0.000

10.000

20.000

30.000

40.000

50.000

1998 1999 2000 2001 2002 2003 2004 2005 2006

RA

C u

nit s

ales

(in

Mio

. uni

ts)

Japan

Asia (excl.Japan)

Middle East

Europe

North America

Central & SouthAmerica

Africa

Oceania

Renewable Energy Week, Brussels, Jan/Feb 2007 5

Resulting increase in electric capacity

0

100

200

300

400

500

1998 1999 2000 2001 2002 2003 2004 2005 2006

tota

l ins

talle

d el

ectri

c ca

paci

ty in

GW

Japan

Asia (excl.Japan)

Middle East

Europe

North America

Central & SouthAmerica

Africa

Oceania

Renewable Energy Week, Brussels, Jan/Feb 2007 6

Why solar heat for cooling / air-conditioning?

• Coincidence of solar

gains and cooling

loads

• Reduce electric

peak loads created

by air-conditioning

• High use of solar

gains during the

entire year

• Reduce summer

surplus solar gains in

solar systems

designed for heating

application (solar

combi-systems)

1 2 3 4 5 6 7 8 9 10 11 12

Heating Cooling

DHW Solar

Renewable Energy Week, Brussels, Jan/Feb 2007 7

Why solar heat for cooling / air-conditioning?

• Coincidence of solar

gains and cooling

loads

• Reduce electric

peak loads created

by air-conditioning

• High use of solar

gains during the

entire year

• Reduce summer

surplus solar gains in

solar systems

designed for heating

application (solar

combi-systems)

7.0heatdriving

coolingusefulCOP ========

1 2 3 4 5 6 7 8 9 10 11 12

Heating CoolingDHW TotalSolar

Renewable Energy Week, Brussels, Jan/Feb 2007 8

Basic system scheme

Thermal driven cooling process

heat

chilled water

conditioned air

Thermallydriven coolingprocess

Renewable Energy Week, Brussels, Jan/Feb 2007 9

• Introduction

• Technologies

• Status, Examples

• Outlook

Technologies

Renewable Energy Week, Brussels, Jan/Feb 2007 10

heat storage cold productionso

lar

colle

ctor

fiel

d

air handling unit

hot w

ater

cold distr. building, loadheat cold storage

chill

ed w

ater

cond

. air

othe

r he

at s

ourc

esheat distr.

chilledceiling

fancoils

heating

heat drivenchiller

desiccant air handling unit

solar collector

Renewable Energy Week, Brussels, Jan/Feb 2007 11

single-effect absorption

double-effectabsorption

adsorption

steam jet cycle

many products for cooling power > 100 kW; few products <100 kW; refrigerant/sorption pair either water/LiBr or ammonia/water

several manufacturers; often direct firedsystems; no products <100 kW; refrigerant/ sorption pair in most cases water/LiBr

a few commercially available systems (Asia); refrigerant/sorption pair water/silica gel

tailor-made sytems for large capacities; refrigerant water

water chillers produce chilled water which can supply any type of air-conditioning equipment (e.g. air handling units, fan-coils, chilled ceilings,....)

Water chillers - market available systems

Renewable Energy Week, Brussels, Jan/Feb 2007 12

Europe is leading in development of

small thermally driven chillers

SK SonnenKlima GmbHSK SonnenKlima GmbHSK SonnenKlima GmbHSK SonnenKlima GmbHEAW

Renewable Energy Week, Brussels, Jan/Feb 2007 13

Desiccant systems - market available equipment

• desiccant systems are used for direct air treatment

• they consist of a combination of

sorptive air dehumidification and evaporative cooling

• 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

• LiCl as desiccant material

Renewable Energy Week, Brussels, Jan/Feb 2007 14

humidifier coolingloads

supply

backupheater

return

desiccant rotor heat recovery

am-bient

ex-haust

Desiccant system schematic

Renewable Energy Week, Brussels, Jan/Feb 2007 15

Temperature needs

• Desiccant systems: 50 – 80°C

– Solar air collectors, flat plate collectors

• Adsorption: 65 – 85°C

– Flat plate collectors, evacuated tubes

• Single-effect absorption (comfort air-conditioning): 70 – 100°C

– Flat plate collectors, evacuated tubes,

optical concentration without tracking

• Double-effect absorption: 130-160°C

– High efficient evacuated tubes, optical

concentration with tracking

Glasabdeckung

Isolierung Kollektorrahmen

Absorber mit Luftkanälen

Glasabdeckung

Isolierung KollektorrahmenAbsorber mit Fluidkanälen

IsolierungKollektorrahmen

Glasabdeckung

Absorber mit Fluidkanal

Reflektor

Folie

Renewable Energy Week, Brussels, Jan/Feb 2007 16

• Introduction

• Technologies

• Status, Examples

• Outlook

Status, Examples

Renewable Energy Week, Brussels, Jan/Feb 2007 17

Status in Europe

• Approx. 120 installations

• Approx. 20

MWcold installed

• Specificcollector area

– 3 m2/kWcold for

chilled water

production

– 10 m2 per 1000

m3/h for

sorptive air

handling units

39.1%

8.7%

27.5%

4.3%

4.3%2.9%5.8%

2.9%1.4%1.4%

1.4%

Germany

Greece

Spain

Portugal

Italy

Austria

France

Netherlands

Israel

Turkey

Serbia (Kosovo)

(2004-values)

Renewable Energy Week, Brussels, Jan/Feb 2007 18

Air-conditioning of a factory

• flat plat collector field: 2700 m2

• 2 adsorptions chillerswith 350 kW cooling capacity each

• 3 compression chillers with 350 kW each

• air conditioning of the production facilities of a cosmetics factory

• site: Inofita Viotias (appr. 50 km north-east of Athens)

• largest system today

� interesting system concept: electricity saving by solar cooling

Renewable Energy Week, Brussels, Jan/Feb 2007 19

Wine store cooling

• evacuated tube collector field: 130 m2

• single-effect absorption chillerwith 52 kWcooling capacity

• no back-up system

• cooling of a wine store (about 3 million bottles) with 3 air handling units (25.000 m3/h air flow)

• site: Banyuls (south France)

• one of the oldest systems; operates more than 12 years without problems

� solar autonomous and not buffer storage ==> storage on load side

Renewable Energy Week, Brussels, Jan/Feb 2007 20

Air-conditioning of a seminar room

• solar air collector as only heat source: 100 m2

• desiccant cooling system (10.200 m3 per hour) with silica gel rotor

• no back-up system

• air-conditioning of the seminar room and the cafeteria in the building of the chamber for trade & commerce in Freiburg/ Germany

• simple solar system with simple integration into the air-conditioning plant

• no back-up, no storage

� promising concept for buildings with a high similarity of cooling loads and solar gains

Renewable Energy Week, Brussels, Jan/Feb 2007 21

Hotel air-conditioning

• parabolic trough collector produces heat

at 180°C: 180 m2 aperture area

• double effect absorption chiller (cooling capacity 116 kW, 4 bar saturated steam; COP > 1.2)

• air-conditioning of a hotel and steam supply for the hotel laundry

• LPG-fired back-up steam boiler

• site: Dalaman (mediterranean coast Turkey)

� first system with double effect chiller

� high overall conversion efficiency

� interesting concept for sites with high direct radiation

Renewable Energy Week, Brussels, Jan/Feb 2007 22

• Introduction

• Technologies

• Status, Examples

• Outlook

Outlook

Renewable Energy Week, Brussels, Jan/Feb 2007 23

Status

• Energy saving

– Primary energy saving for properly designed chilled water systems 40 – 60 %

– Primary energy saving for properly designed open cycles 20 – 50 %

• First cost

– 2 – 2.5 times higher compared to conventional reference systems

• Overall annual cost

– 1.2 – 1.5 times higher compared to conventional reference systems

– Close to break-even with funds in the range of 100 € per m2 of collector

• Large potential, in particular in mediterranean countries

• Potential for cost reduction

– Higher standardization

– Less effort in planning and design

– Lower component cost

Renewable Energy Week, Brussels, Jan/Feb 2007 24

Main future needs

• standardized systems

• small capacity systems

• advanced operation & control

• transfer to professionals

… thank you for your attentionTask 38Solar Air-Conditioningand Refr igeration

Renewable Energy Week, Brussels, Jan/Feb 2007 25

Cooling with low driving tempertature

• Small commercial applications: offices, surgeries etc.

• Residential: single-family, multi-family

Renewable Energy Week, Brussels, Jan/Feb 2007 26

Fan-coil system – single-effect absorption chiller

buffer storage

backup heater

absorpt.chiller

fancoils

• Mainly commercial buildings: medium to large offices, hotels

• Production facilities

Renewable Energy Week, Brussels, Jan/Feb 2007 27

Fan-coil system – double-effect absorption chiller

buffer storage

backup heater

absorpt.chiller

fancoils

• Mainly commercial buildings or cooling networks

• High fraction of direct solar radiation necessary

Renewable Energy Week, Brussels, Jan/Feb 2007 28

fancoils

absorpt.chiller

icestorage

drycooling

System for hot climate

• Ice storage, food production

• High fraction of direct solar radiation necessary