Refrigeration cycle apparatus and air conditioner (as amended)

Abstract

An air conditioner is a refrigeration cycle apparatus in which incompatible oil is employed as refrigerating machine oil, and includes a compressor to compress refrigerant, a first heat exchanger to condense the refrigerant output from the compressor, a pressure reducing device to reduce a pressure of the refrigerant output from the first heat exchanger, and a second heat exchanger to evaporate the refrigerant output from the pressure reducing device and output the resultant refrigerant to the compressor. The second heat exchanger includes a heat transfer tube having a groove formed on an inner surface of the heat transfer tube. The groove of the heat transfer tube is formed such that an inner surface area of the heat transfer tube on a downstream side of the heat transfer tube is smaller than an inner surface area on an upstream side of the heat transfer tuber.

1 . A refrigeration cycle apparatus in which incompatible oil is employed as refrigerating machine oil, the refrigeration cycle apparatus comprising:
 a compressor configured to compress refrigerant;   a first heat exchanger configured to condense the refrigerant output from the compressor;   a pressure reducing device configured to reduce a pressure of the refrigerant output from the first heat exchanger; and   a second heat exchanger configured to evaporate the refrigerant output from the pressure reducing device to output the refrigerant to the compressor, wherein   the second heat exchanger includes a heat transfer tube having a groove formed on an inner surface of the heat transfer tube, and   the groove is formed such that an inner surface area per unit length of the heat transfer tube on a downstream side of the heat transfer tube is smaller than an inner surface area per unit length of the heat transfer tube on an upstream side of the heat transfer tube,   the heat transfer tube includes:
 a first part; and 
 a second part located downstream of the first part, 
   the groove is formed such that the inner surface area in the second part is smaller than the inner surface area in the first part, and   a boundary between the first part and the second part is located in a region where flow regime of refrigerant flowing through the heat transfer tube changes,   the first part includes at least one first tube connected in series,   the second part includes at least one second tube connected in series, and   the at least one first tube and the at least one second tube are formed such that a connecting part that connects the at least one first tube and the at least one second tube to each other is included in the region.   
     
     
         2 - 3 . (canceled) 
     
     
         4 . The refrigeration cycle apparatus according to  claim 1 , further comprising:
 a temperature sensor configured to detect a state of the refrigerant; and   a detector configured to detect the flow regime of the refrigerant at the boundary.   
     
     
         5 . The refrigeration cycle apparatus according to  claim 4 , wherein the temperature sensor detects
 an inlet-side refrigerant temperature of the first heat exchanger, an outlet-side refrigerant temperature of the first heat exchanger, a heat transfer tube temperature of the first heat exchanger, and an ambient temperature of the first heat exchanger, and   an ambient temperature of the second heat exchanger and a heat transfer tube temperature of the second heat exchanger.   
     
     
         6 . The refrigeration cycle apparatus according to  claim 1 , further comprising a sensor placed at the boundary and configured to detect the flow regime of the refrigerant at the boundary. 
     
     
         7 . The refrigeration cycle apparatus according to  claim 6 , wherein the sensor includes a luminosity sensor configured to detect a state of the refrigerant at the boundary. 
     
     
         8 . The refrigeration cycle apparatus according to  claim 6 , wherein the sensor includes an acoustic wave sensor configured to detect a state of the refrigerant at the boundary. 
     
     
         9 . The refrigeration cycle apparatus according to  claim 4 , wherein
 the pressure reducing device includes a pressure reducing valve,   the refrigeration cycle apparatus further comprises a controller configured to control an opening of the pressure reducing valve, and   the controller is configured to
 increase the opening when the detected flow regime is annular flow or annular mist flow, and 
 decrease the opening when the detected flow regime is not annular flow or annular mist flow. 
   
     
     
         10 . The refrigeration cycle apparatus according to  claim 4 , further comprising a controller configured to control an operating frequency of the compressor, wherein
 the controller is configured to
 decrease the operating frequency when the detected flow regime is annular flow or annular mist flow, and 
 increase the operating frequency when the detected flow regime is not annular or annular mist flow. 
   
     
     
         11 . The refrigeration cycle apparatus according to  claim 4 , further comprising:
 a fan provided for the second heat exchanger; and   a controller configured to control a rotational speed of the fan, wherein   the controller is configured to
 decrease the rotational speed when the detected flow regime is annular flow or annular mist flow, and 
 increase the rotational speed when the detected flow regime is not annular flow or annular mist flow. 
   
     
     
         12 . An air conditioner comprising the refrigeration cycle apparatus according to  claim 1 . 
     
     
         13 - 14 . (canceled)