To eliminate the need of particular provision of a pressure reduce by providing with a pressure reducing function a site-laid refrigerant piping connecting between an outdoor heat exchanger and an indoor heat exchanger.
In cooling operation, a four-way valve 2 is operated into a state where connection ports A and D, B and C thereof are interlly connected. High temperature high pressure refrigerant vapor discharged from the compressor 1 flows onto the outdoor heat exchanger 3 after passage through the connection ports A, D, and radiates heat to outdoor air sent form an outdoor fan 8. The refrigerant which has radiated the heat is condensed and liquefied into a liquid refrigerant, and enters a refrigerant liquid connection piping 4. Herein, the refrigerant liquid connection piping 4 is reduced in pressure under the indications that the piping 4 is provided with a pressure reducing function, and becomes a two phase flow of gas/liquid mixture. The low temperature low pressure refrigerant as the two phase flow is guided to an indoor machine, and enters an indoor heat exchanger 6 to effect heat exchange with indoor air sent from the indoor fan 9.
NAITO YASUHIRO
KAWAGUCHI HIROMI
HITACHI SHIMIZU ENG KK