Experimental investigations on air side heat and mass transfer phenomena in evaporative condensers

The evaporative cooling is an energy saving technology and for this reason is widely used both in industrial and civil fields. The heat and mass transfer phenomena occurring inside their tube banks are hard to study and even if many researchers have faced them, further activities need to be carried out. For this reason, this work aims at investigating with an experimental approach the evaporative condensers performance at the tube scale, focusing on the air side where more complex physical interactions occur. A test rig has been set up made of a rectangular transparent channel where electrical heaters simulate the refrigerant side and embedded Pt100 Resistance Temperature Detectors controlled by a PID set and keep constant a given outer surface temperature. Water and air operating conditions are controlled as well, and this allows to carry out a sensitivity analysis depending on all the parameters influencing those thermo-fluid dynamic phenomena. The results show that the cooling rate decreases with the air relative humidity and dry bulb temperature, while increases with water flow rate and temperature. For the testing cases the maximum improvements deriving from increasing water flow rate and temperature are of 37 % and 14 % respectively.