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Technology - Absorption Chillers
Because the absorption chiller requires hot water at temperatures up to 205°F, evacuated tube collectors are used in our systems. Collectors are used in applications that require temperatures over 150°F because of their high efficiencies at those temperatures. Their cylindrical shape also allows them to shed dust and dirt that would otherwise accumulate on a flat surface.
The glass tube is made of a durable borosilicate material. Since the collectors are modular, tubes can easily and inexpensively be added, removed or replaced.
When evacuated tubes are made, air is evacuated from the space between the two tubes, forming a vacuum. Conductive and convective heat losses are eliminated because there is no air to conduct heat or to circulate and cause convective losses. The collectors perform well in both direct and diffuse solar radiation.
The glass tube is made of a durable borosilicate material. Since the collectors are modular, tubes can easily and inexpensively be added, removed or replaced.
When evacuated tubes are made, air is evacuated from the space between the two tubes, forming a vacuum. Conductive and convective heat losses are eliminated because there is no air to conduct heat or to circulate and cause convective losses. The collectors perform well in both direct and diffuse solar radiation.
Collector Facts
The collector is made up of a series of evacuated glass tubes, which are connected to a manifold at the top. An array of these collectors is constructed on your building’s roof.The heat is transferred to a heat pipe. In turn, the pipe transfers heat to the water flowing through the collectors.
Evacuated-tube collectors achieve high temperatures and do radiate some of the heat gained but these losses are small compared to the amount collected.
An advantage of heat pipes is the "dry" connection between the absorber and the header, which makes installation easier and also means that individual tubes can be exchanged without emptying the entire system of it’s fluid.
Outer Tube
When sunlight passes through the clear glass tube, it strikes the absorber plate, which is coated with a selective coating making it very efficient in absorbing and retaining heat.Inner Tube
A vacuum exists between the tube’s double glass walls. The vacuum enables the liquid to boil at a much lower temperature than it would at normal atmospheric pressure.A round black copper absorber plate inside the tube’s double glass wall wraps around a heat pipe. The heat pipe is hollow and the space inside, like that of the solar tube, is evacuated.
As liquid inside of the heat pipe vaporizes, it convects heat to the collector’s manifold and heats the water.