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IEA Solar Heating and Cooling Programm - NachhaltigWirtschaften.at

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<strong>IEA</strong> SHC Task 38 <strong>Solar</strong> Air Conditioning <strong>and</strong> Refriger<strong>at</strong>ion<br />

Subtask A Report, D<strong>at</strong>e:…<br />

1 Background<br />

In solar thermal install<strong>at</strong>ions, both solar cooling <strong>and</strong> solar he<strong>at</strong>ing can be provided<br />

synergistically, yielding a complete annual utiliz<strong>at</strong>ion. During the cold season, solar he<strong>at</strong><br />

serves for space he<strong>at</strong>ing. During the warm season, solar he<strong>at</strong> can be converted into useful<br />

cold by means of sorption cooling. A favorable situ<strong>at</strong>ion is given when low temper<strong>at</strong>ure<br />

he<strong>at</strong>ing <strong>and</strong> cooling facilities, e.g. floor or wall he<strong>at</strong>ing systems or activ<strong>at</strong>ed ceilings, are<br />

applied for he<strong>at</strong>ing <strong>and</strong> cooling. During he<strong>at</strong>ing oper<strong>at</strong>ion, a low temper<strong>at</strong>ure l<strong>at</strong>ent he<strong>at</strong><br />

storage can be used to balance the he<strong>at</strong> gener<strong>at</strong>ion by the solar thermal system <strong>and</strong> the<br />

he<strong>at</strong> supply to the he<strong>at</strong>ing system. Thus, a low oper<strong>at</strong>ing temper<strong>at</strong>ure of the solar thermal<br />

system is accomplished yielding efficient oper<strong>at</strong>ion with optimum solar gain.<br />

In cooling mode, the same storage is used in combin<strong>at</strong>ion with a dry cooling tower to<br />

absorb/reject the waste he<strong>at</strong> in order to replace a wet cooling tower. By th<strong>at</strong> means he<strong>at</strong><br />

rejection of the chiller is shifted partly to periods with lower ambient temper<strong>at</strong>ures, i.e. night<br />

time, or to off-peak hours.<br />

2 System Design<br />

In conventional absorption cooling install<strong>at</strong>ions, wet cooling towers designed for a coolant<br />

supply/return temper<strong>at</strong>ure 27/35 °C are applied. To use a dry air-cooler, cooling w<strong>at</strong>er<br />

temper<strong>at</strong>ures have to be increased to 40/45 °C. As a consequence of the increase of the<br />

cooling w<strong>at</strong>er temper<strong>at</strong>ure, the temper<strong>at</strong>ure level of the driving he<strong>at</strong> supplied to the<br />

regener<strong>at</strong>or of the absorption chiller has to be increased accordingly.<br />

Daytime oper<strong>at</strong>ion of the chiller<br />

SOLAR<br />

CHILLER<br />

90°C<br />

COOLING<br />

15°C<br />

HOT<br />

50 % dry<br />

18°C<br />

WATER<br />

AUX.<br />

he<strong>at</strong> rejection<br />

TANK<br />

BOILER<br />

50 % loading<br />

40°C<br />

32°C<br />

80°C<br />

l<strong>at</strong>ent he<strong>at</strong><br />

storage<br />

DRY AIR<br />

COOLER<br />

40°C<br />

32°C<br />

32°C<br />

SOLAR<br />

SYSTEM<br />

36°C<br />

36°C<br />

HEATING /<br />

LATENT<br />

COOLING<br />

HEAT<br />

SYSTEM<br />

STORAGE<br />

SOLAR<br />

COOLING<br />

unloading<br />

l<strong>at</strong>ent he<strong>at</strong><br />

storage<br />

He<strong>at</strong> dissip<strong>at</strong>ion during night time<br />

CHILLER<br />

HOT<br />

WATER<br />

TANK<br />

AUX.<br />

BOILER<br />

DRY AIR<br />

COOLER<br />

26°C<br />

26°C<br />

18°C<br />

SOLAR<br />

SYSTEM<br />

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