Working Principle of Evacuated Tube Collector (ETC) System :
ROYAL Solar Water Heater (ETC System) works on a simple principle ‘Black body heat absorption principle’. The principle says, ‘black colour absorbs maximum heat, more than any other colour’.
Solar water heating systems using vacuum tubes made of borosilicate glass with special coating to absorb the solar energy are called as Evacuated Tube Collector system (ETC Systems).
Vacuum tube, as shown in the sketch, is the main component, which absorbs solar energy. The vacuum tube is an assembly of two concentric, borosilicate glass tubes.
Air between the gap of two glass tubes is evacuated. It results in high level of vacuum, which acts as the best insulation to minimize the heat loss from inner tube. The black coating on the inner tube absorbs the solar energy and transfers it to the water. The water on upper side of Vacuum Tube becomes hot and thus lighter, so it starts moving upwards in the tank. At the same time cold water, which is heavy, comes downward from the tank and is stored at the bottom. The phenomenon is called as natural Thermosyphon circulation, which occurs in every tube.
Thermosyphon Systems : In this type water flows through the system and when water gets warm it rises as cooler water sinks. The collector is installed below the storage tank so that warm water will rise into the tank. These systems do not involve any pump and are more reliable.
Solar Water Heaters have several advantages over conventional water heating systems as they :
- Reduce electricity bills: 40% of an average household’s energy bill comes from water heating.
- Save interior space: These systems are usually located on rooftops.
Increase safety: Solar water heaters eliminate the risk of accidents in bathrooms due to electric water heating equipment. - Quick payback: On average, a good quality solar water heater will have a payback period of 1½ – 2 years in Indian conditions.
- Protect the environment: In today’s environment conscious world, you can make a difference by getting your hot water free from the sun. By replacing an electric water heater with a solar water heater, you can reduce greenhouse gas emissions by up to 3 and 4 tonnes a year – the equivalent of taking a small car off the road.
Evacuated Solar Tube:
- All glass evacuated Borosilicate solar tube
- High Solar-thermal conversion and low heat loss
- Stable advanced selective coating
- High level vacuum ensure operation under cold weather
- Tube material: Special grade Borosilicate glass
- outer tube diameter: 47 mm
- inner tube diameter: 37 mm
“Royal” Evacuated Tube Collector Solar Water Heaters:
- Excellent insulation of glass tubes- Vacuum
- Selective coated glass tube
- Evacuated tubes are self-tracking
- Compatible with hard water
- Easy to install & operate
- Easy replacement of tubes
- Minimal maintenance
Working Principle of ETC Solar Water Heaters:
Compact Solar Water Heater relies on warm water rising, a phenomenon known as natural convection, to circulate water through the collector and to the tank.
In this type of installation, insulated tank must be the hot water collector.
As water in the Evacuated tubes heats, it becomes lighter and naturally rises in to the tank above. Meanwhile, cooler water in the tank flows downward into the glass tubes, thus causing circulation throughout the system.