Mechanism of solar water heater
Mostly we build up a water tank with a solar screen on the top—the top solar acts as the heat absorber. Once the Sundays hit the screens directly, then it serves the heat to the water now. In some cases, there are advanced heat-absorbing liquid or fluid to heat the water only when we need to use it. Other than that, we can directly store hot water in some insulated or preheated water tanks. Pipes supplying water from this solar heater usually have a coat of heat non-conductive material to prevent any heat loss in the way. Depending on the mechanisms and storage capabilities, there are five types of solar water heaters available in the market for domestic usage. Such as
Thermosiphon tube system
Here water temperatures rise naturally by the convection of water level. We can use a tube to bring the water from the storage tank to a higher level temporarily. Fluid shift and friction raise the temperature relatively high. Sun radiation does the rest of the job. Here we do not need any pump or mechanical force to generate heat. So, it is the most convenient and user-friendly mechanism nowadays. But, you have to make sure that you live in a tropical Region and get sunlight for most of the daytime. This system applies to antifreeze substances like glycol, ethanol, and such. Then comes the
Direct circulation system
Here we mainly bring the water from the storage hold to the vents. And then we have to flush the duct frequently with hot water or air. The continuous flushing process increases energy usage and thus production cost. It is also less convenient than the Siphon Tube technology. Mostly we can use this technology where the temperature tends to be freezing very frequently.
Drain down system
It is another way of solar water heating. But, in this drain-down method, solar energy works as a secondary source of heat. Treated or untreated water comes into the heater via some loops, and we supply heat to the water through a heat exchange mechanism. Once the water reaches the optimum temperature, we have vaults with thermal insulation to maintain the temperature. In case of overheating, gravity pulls down the water and gets out of the heat exchanging system. Thus, the temperature reduces back to normal.
Air vent is one of the newest editions in water heating technology. Here we heat the air and not the water directly. Water remains in the tank, and there are looping pipes surrounding the water tank. Once we let the hot airflow through the vents, cold water sucks in the temperature. One of the primary rules of thermodynamics is in action here. Heating water through an air vent is more or less fifty percent effective.