DIRECT-EXPANSION AIR-CONDITIONING SYSTEM CAPABLE OF PERFORMING ULTRALOW-TEMPERATURE COOLING OPERATION

摘要

A direct-expansion air-conditioning system capable of performing ultralow-temperature cooling operation, comprising an outdoor unit and an indoor unit. The outdoor unit comprises a compressor (1), a main four-way valve (3), an auxiliary four-way valve (4), outdoor heat exchangers (8), and a gas-liquid separator (14); the indoor unit comprises a first indoor heat exchanger (10) and second indoor heat exchangers (11); the number of the outdoor heat exchangers (8) is two or more, and the outdoor heat exchangers are connected in parallel; the inlet gathering ends of the outdoor heat exchangers are connected to the port C of the main four-way valve (3), and the outlet gathering ends of the outdoor heat exchangers are simultaneously connected to a liquid pipe end of the first indoor heat exchanger (10) and the liquid pipe ends of the second indoor heat exchangers (11); the inlet end of each outdoor heat exchanger (8) is separately provided with an electric ball valve (5) or an outdoor electromagnetic valve (6); the number of the second indoor heat exchangers (11) is two or more, and the second indoor heat exchangers are connected in parallel; the air pipe end of each second indoor heat exchanger (11) is gathered and then connected to the port C of the auxiliary four-way valve (4); the air pipe end of each second indoor heat exchanger (11) is separately provided with or not provided with an indoor electromagnetic valve (13). The ultralow-temperature cooling operation of a unit is ensured by means of the segmented adjustment of a plurality of indoor heat exchangers.