Although the Kigali Amendment to the Montreal Protocol has made progress with the regulation of HFC refrigerants, emerging countries are still exempt from the reduction scheme. The increase in the air conditioning demand resulting from economic growth is expected to increase both amounts of HFC and HFO refrigerants in use. Therefore, we have developed large-capacity centrifugal chillers with a maximum capacity of 5,000 refrigeration tons (RT) which share most of the equipment configurations in either HFC or HFO refrigerant. Retaining the same configurations in most parts, these chillers for the two types of refrigerants are characterized by the high efficiency enabled by a series counterflow (SCF) configuration in which a single chiller has two serially arranged compressors, and the capability of easily handling the change in the refrigerant type in use owing to the same built-in control system despite the differences between HFC and HFO refrigerants. Moreover, the high-efficiency operation of plant facilities has been enabled by adopting the SCF configuration of two chillers and by controlling the number of units in operation through the dedicated control panel. This article presents the technologies applied for the development of high-efficiency large-capacity centrifugal chillers.
