Environmental Engineering Reference
In-Depth Information
Figure 3.4
Schematic of a Double-Cycle System with Forced Circulation
S
OLAR
C
OLLECTORS
To obtain the higher temperatures required for domestic water heating, the
following collector types are available:
•
integral storage collector systems
•
flat-plate collectors
•
evacuated flat-plate collectors
•
evacuated tube collectors.
The flat-plate collectors and evacuated tube collectors always need a storage
tank. The collector water volume itself is very low and water temperatures
inside the collector can reach much more than 100°C if the water is not
continuously replaced. The collector efficiency also decreases significantly at
high operating temperatures. Therefore, all solar collector systems for domestic
water heating need a hot water storage tank to store larger quantities of
absorbed collector heat and to provide a hot water supply during bad weather
periods and darkness. In contrast, for solar swimming pool systems, the pool
water itself is the storage.
Integral collector storage systems
For integral collector storage systems (ICS) the hot water storage tank is
integrated with the collector itself. A technically robust system is not easy to
