Design and Operation
Solar water heating is a system that uses the heat of the sun to effectively heat water for households and commercial use. Solar heaters use collectors to capture and absorb solar energy. Some systems use a flat plate design composed of insulated boxes which house a black absorber plate that is surrounded by layers of glass. The heat travels through the glass and strikes the absorber plate, becoming trapped in the process. Liquid-filled tubes attached to the absorber plate carry the heated water wherever it is needed. Liquid to liquid systems use a transfer fluid that is heated, and then convey the heat to a separate water supply. Passive solar heat exchanger consist of an absorber material and a piping system which uses no moving parts, whereas an active system might use a pump to move larger water volumes. The coil-in-tank design uses a simple tube inside a storage tank. A tube-in-tube systems has an outer and inner tube allowing direct fluid to fluid contact. Shell-and-tube systems use two tubes encased in a shell outside the storage tank, allowing fluid to travel in opposite directions. Solar heat exchangers have many benefits over conventional heat exchanger designs.
Solar water heaters can produce a temperature increase in almost any climate. This depends upon the amount of solar energy provided and the water source, but they can typically cause a temperature variation from incoming water of 60 degrees to 90 degrees Fahrenheit. In freezing temperatures, Glycol is used, which has antifreeze capabilities to minus 60 degrees Fahrenheit. Due to the absorption effectiveness of the plate, coil or tube material over a sustained period of solar energy radiation; even a weak solar emission is magnified and sustained.
Electricity and Fuel Savings
Solar energy is cost-free, negating the use of electrical components needed to heat coils, tubes or plates, other than an assist pump to circulate the fluid when needed. This substantially reduces the electrical heating bill by as much 50 to 80 percent, which begins to show dividends after the initial purchase and installation is recouped. The requirement for oil, wood or coal fuels used to heat the incoming water are non-existent, allowing additional savings.
Depending upon the complexity of the system, solar heat exchangers are less likely to fail or breakdown and the maintenance requirements are reduced. The passive solar heat exchangers excel in this area. Solar heat exchangers can be dismantled and cleaned thoroughly, often times by the homeowner or resident. On the other hand, boilers and furnaces, used to heat incoming water, develop performance problems or fail and can cause high repair costs.
Solar heat exchangers are environmentally friendly, since they produce no toxic emissions or chemicals that are harmful to the environment. They are less likely to cause health problems in a building structure should they emit airborne particles or leak fuel oil. These factors promote self-sufficiency and safety, as well as safeguarding the environment.
About the Author
Elliot Delaney is a writer for Brazetek.com, a leading online retailer of brazed plate heat exchangers