Beginning
A new form of cooling is hybrid dry air coolers that are used in industrial refrigeration applications, including industrial and process refrigeration, air conditioning and ambient temperature control of buildings.
Since 1991, these products have been installed in regions where water conservation and low energy consumption are the main requirements. They are also ideal for projects where available space is limited and where low noise levels are required.
Hybrid air coolers consume only electrical energy in dry mode and electric power and water in hybrid mode. Its operation and usefulness has been successfully tested in more than 1,000 installations in different countries.
Operation
These air coolers are characterized because the heat exchangers are arranged in a V-shape (figure 1) and include 4 main parts: stainless steel frame, insulated heat exchangers with fins, very quiet fans and a wetting system.
The basis of operation of the hybrid air cooler combines two known forms of heat transmission. On the one hand dry cooling and on the other evaporative cooling.
Its operation according to Figure 2 is as follows: The hot fluid of the process is transported by means of a pump (6) to a closed primary cooling circuit (1), from the heat source (5) to the fin cooling elements (3). In a countercurrent process – cross is found in the cooling elements the hot process fluid and the cooling air (11) sucked by the fan (12). In this case dry refrigeration takes place. Precisely under cold weather conditions and at night this process is sufficient. On the contrary, for high outdoor temperatures there may be power drops that cannot be absorbed by dry cooling. The hybrid refrigerator uses the principle of evaporation to achieve higher yield. Through a wetting circuit (7) a pump installed in the water collector basin (9) transports water to the upper end of the cooling element. The cooling element is evenly moistened by falling water. The flowing air allows the evaporation of a part of the water in circulation on the surface of the fins and evacuates heat from the fin and with it from the process fluid. Because of the evaporation of water, the level drops. The water level should not fall below a certain value to protect the wetting pump. To do this, water is fed through a valve (8). By means of evaporation and feeding, water increases the density, that is, the concentration of dissolved salts in the water increases. To avoid too high a concentration, concentrated water is removed from the circuit through a so-called purge tap (10).
