solar evacuated tube collectors

solar evacuated tube collectors

SOLAR WATER HEATER DESIGN & WORKING

Solar water heating is a popular means of ensuring hot water supply. Various models of solar water heaters exist, though the basic solar water heater design remains the same.

 

The solar water heater working includes a heat collector (to collect photons from sunrays) and a storage tank with coils that heat the incoming water. The solar water heater can either be passive or active; the only difference in the solar water heater working is whether the flow of water is due to gravity (passive) or a pump (active).

 

Another choice in the solar water heater design is that of heat transfer method – open-loop (direct) or closed-loop (indirect). Either can be used with the active or the passive solar water heater working. The first involves passing water directly through the collector and storage tank. The second involves the use of a non-toxic heat transfer fluid to warm the water.

 

Yet another difference in solar water heater working is the installation of one-tank or two-tank system. Here, the difference in the solar water heater working lies in pre-heating of water in the latter system, due to the extra tank, which maximizes efficiency (though the first is cheaper and easier to install).

 

Other factors also determine a specific solar water heater design and its working. One of the challenges faced by the solar water heater working system is the loss of heat: thus, the different types of collectors. ICS / batch collectors, the simplest passive solar water heater design, have the tank in a box with thermal insulation – a tank enclosed in an ‘oven'. Flat plate collectors go further – the insulated tank contains a dark absorber plate beneath transparent sheets. The third type of solar water heater design has evacuated tube collectors; a vacuum is created to keep heat inside. Each solar water heater working method is useful in different conditions.

 

A modern solar water heater design includes an electric or gas fuel backup, for rainy, cloudy days. Today, it can also include an electronic controller for smoother consumer control over its functions.

 

Yet another hindrance is cold temperatures, which again the solar water heater working tries to overcome. Solar water heaters in Europe are equipped with anti-freeze measures to prevent harm from the expansion of the transfer fluid. There is more than one solar water heater design to accomplish this task: in some, the fluid is drained away once pumping stops; in others, anti-freeze transfer fluid is used or freeze tolerant solar collectors.

 

There are also measures included in the solar water heater design of some makes to prevent the opposite from happening, i.e. from the water getting too hot during bright sunshine. Relief valves, heat dumps, open vents are all ways in which high temperature of the water in the storage tank, when not being used, does not conflict with the solar water heater working.

 

The solar water heater design is therefore one that works with a combination of energy collectors and storage tanks.

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Solar Hot Water: Calpak VTN Evacuated Tube Solar Thermal Collector