Panama. Engineer Pedro Vásquez, president of the Panamanian Association of Air Conditioning and Refrigeration (Apayre), made some observations about air-cooled chillers, in which he seeks to compare from the economic aspect the performance of the equipment selected for the system.
Initially, he explained that the equipment "has been continuously improved and for example, in 1998 they had for full load a COP of 1.23 kW/Ton (9.75 EER) and for partial load IPLV a COP of 0.98 kW/Ton (12.24 EER). The current ones have for full load a COP of 1.01 kW /Ton (11.8 EER) and for partial load IPLV a COP of 0.61 kW/Ton (19.4 EER).
The engineer listed some of the advantages of air-cooled chillers with a modulating screw compressor (sliding valve or VFD) over a water-cooled centrifugal one:
(a) Positive displacement compression without waves (surges);
(b) No cooling towers;
(c) No consumption costs and water losses;
(d) No chemical costs;
(e) No condensing water pumps and pipes;
f) Saving space in the machine room
(g) Reasonable maintenance costs.
Pedro Vásquez affirms that the characteristics listed above must be evaluated technically and economically with respect to the greater efficiency, but with higher initial costs, obtained using centrifugal chillers cooled by water.
"For example, for a capacity of 385 Tons, a Premium type variable speed air-cooled screw chiller has a COP of 0.623. For the same capacity one of constant speed centrifuge cooled by water has a COP of 0.587, if this has a variable speed compressor then the COP is 0.480 and using a centrifuge of variable speed and magnetic chumaceras you have an appreciable COP of 0.405. The dilemma as always is the initial cost vs the cost of operation, "concluded the president of Apayre.
