A solar thermal system can be active or passive, This term relates to the movement of the heat transfer liquid through the solar collector.
Active Solar Systems:
Active systems utilize a circulation pump to move the liquid through the collector.
So storage tanks can be located were needed.
- There is /3/ types of active solar systems:
1- Open-Loop Active Systems - Direct Circulation:
Open Loop Systems are suitable for single application domestic hot water (DHW) systems, in mild and moderate climates where there is no risk of freezing.
Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
Re-circulation systems are a specific type of open-loop system that provide freeze protection. They use the system pump to circulate warm water from storage tanks through collectors and exposed piping when temperatures approach freezing.
2- Closed-Loop Active Systems - Indirect Circulation (our case):
Suitable for single and multiple solar heating application systems, e.g. domestic solar water heating (single), solar water heating hot tub, solar swimming pool heating or solar space heating systems. Suitable for areas with questionable water quality and all climate conditions. Preferred option for extremely cold areas.
Suitable for commercial projects, can provide higher temperatures than other systems if needed.
Pumps circulate a non-freezing, heat-transfer fluid through the collectors and a heat exchanger. They are popular in climates prone to freezing temperatures.
These systems pump heat-transfer fluids (usually a glycol-water antifreeze mixture “10-40% glycol”) through collectors. Heat exchangers transfer the heat from the fluid to the household water stored in the tanks. Closed-loop glycol systems offer good freeze protection.
Types of heat exchangers used for (Closed-Loop Active Systems - Indirect Circulation) are internal or External.
3- Drain-back Systems Active Systems: these systems use water as the heat-transfer fluid in the collector loop. A pump circulates the water through the collectors. The water drains by gravity to the storage tank and heat exchanger; there are no valves to fail. When the pumps are off, the collectors are empty, which assures freeze protection and also allows the system to turn off if the water in the storage tank becomes too hot.
ความคิดเห็น