Solar water heating system is useful for people to supply warm water, moreover in cold condition. There are some types of solar water heating systems such as:
- Type solar water heating thermo siphon
Type water heating thermo siphon is one of types of solar water heating systems in which it is the simplest conversion system of solar energy and most effective. As shown in Figure 1, this system consists only of water storage tank that is placed higher at distance at least 25 cm above the top of row solar collectors. There are differences of density between fluid in column AB and fluid in column A'B '. If the fluid in solar collector (column AB) is heated by sun, then its density will decrease.
If difference of density between AB and A'B 'have been high enough to overcome the friction of system, then clockwise circulation will occurs, warm water from solar collector is distributed to water storage tank and blank space in solar collector will be replaced by cooler water from bottom of tank. The circulation continues until entire system achieves uniform temperature.
|Figure 1: Type Solar Water Heating Thermo Siphon|
- Type forced circulation of water glycol systems
If protection against freezing is needed, then solution of antifreeze can be circulated through solar collectors, absorbed heat will be transferred to water in storage tank by using heat exchanger (Figure 2). If the frozen solution is toxic, it would require heat exchanger that is made with double walls.
|Figure 2: Type Forced Circulation of Water Glycol Systems|
- Type drain back System
One of types of solar water heating systems is drain back system which uses compressed air to restore water that circulates through solar collector to storage tank when the insulation is not enough. Compressed air can be supplied by a compressor to spray grain water. The circulating water is usual drinking water; in this case heat exchanger is not used. Water is supplied from preheated tank to hot water heater based on requirement. Type drain back system is shown in Figure 3 in which soft water is circulated through solar collector to prevent deposition on the tube and ventilation hole is made on polypropylene tank.
|Figure 3: Type Drain Back System|
Type flat plate solar water heater is one of types of solar water heating systems that consist of a sheet of thermal conductive material which is called absorber plates that is connected to pipes to distribute hot water. Solar radiation is transmitted through transparent cover and converted into heat at absorber plate. The bottom and sides are isolated as shown in Figure 4.
|Figure 4: Type Flat Plate Water Heater|