Air-conditioning apparatus

Abstract

An air-conditioning apparatus that includes a refrigeration cycle in which a compressor, a heat-source side heat exchanger, an expansion unit, and a load-side heat exchanger are included and are connected with refrigerant pipes, includes cutoff units capable of flowing or cut off a refrigerant circulating in the refrigeration cycle; a detection unit detecting leaking of the refrigerant on the basis of a resistance that changes with densities of plural kinds of leaked refrigerants; a concentration calculation unit calculating a concentration of a refrigerant that has leaked, on the basis of the resistance of the detection unit; a concentration detection unit outputting a calculation result of the concentration calculation unit in order that the calculation result is used for controlling the cutoff units; and a cutoff control unit controlling the cutoff units on the basis of an output of the concentration detection unit.

1 . An air-conditioning apparatus that includes a refrigeration cycle in which a compressor, a heat-source side heat exchanger, an expansion unit, and a load-side heat exchanger are included and are connected with refrigerant pipes, the air-conditioning apparatus comprising:
 a cutoff unit capable of flowing or cutting off a refrigerant circulating in the refrigeration cycle;   a detection unit detecting a resistance that changes with densities of plural kinds of leaked refrigerants;   a concentration calculation unit calculating a concentration of the refrigerant that has leaked, on the basis of the resistance of the detection unit;   a concentration detection unit outputting a calculation result of the concentration calculation unit in order that the calculation result is used for controlling the cutoff unit; and   a cutoff control unit controlling the cutoff unit on the basis of an output of the concentration detection unit, wherein   at least R410A, R407C, R32, R404A, HFO1234yf, HFO1234ze, a refrigerant mixture including R32 and HFO1234yf, and all refrigerant mixtures including at least one of these refrigerants as a component are detectable by the single detection unit.   
     
     
         2 . The air-conditioning apparatus of  claim 1 ,
 wherein the detection unit is formed using a stannic oxide semiconductor (SnO 2 ).   
     
     
         3 . (canceled) 
     
     
         4 . The air-conditioning apparatus of  claim 1 ,
 wherein the concentration calculation unit   is capable of calculating the concentration of the refrigerant that has leaked, by using a single relational expression regarding changes in the resistance and in concentration, for R410A, R407C, R32, HFO1234yf, HFO1234ze, a refrigerant mixture including R32 and HFO1234yf, and all refrigerant mixtures including at least one of these refrigerants as a component.   
     
     
         5 . The air-conditioning apparatus of  claim 1 ,
 wherein the concentration detection unit   outputs a predetermined signal that makes the cutoff unit cut off circulation of the refrigerant to the cutoff control unit   in a case where a calculation result regarding the concentration of the refrigerant from the concentration calculation unit is greater than or equal to a predetermined value.   
     
     
         6 . The air-conditioning apparatus of  claim 5 ,
 wherein the predetermined signal is within 1 (V) to 24 (V).   
     
     
         7 . The air-conditioning apparatus of  claim 1 , further comprising
 an outdoor unit including the compressor and the heat-source side heat exchanger,   wherein the cutoff unit   is provided in the outdoor unit or near the outdoor unit.   
     
     
         8 . The air-conditioning apparatus of  claim 1 ,
 wherein the cutoff control unit is a non-contact relay formed with a semiconductor element.   
     
     
         9 . The air-conditioning apparatus of  claim 1 ,
 wherein the cutoff unit is in an open state when energized and in a closed state when not energized.   
     
     
         10 . The air-conditioning apparatus of  claim 7 ,
 wherein the cutoff unit   is one of a plurality of cutoff units and at least one cutoff unit is provided at each of an outlet out of which the refrigerant flows from the outdoor unit and an inlet into which the refrigerant flows toward the outdoor unit.   
     
     
         11 . The air-conditioning apparatus of  claim 1 ,
 wherein the cutoff unit is a two-way valve including a valve body, a sealing material that seals the valve body, and a coil that opens and closes the valve body by electromagnetic force.   
     
     
         12 . The air-conditioning apparatus of  claim 11 ,
 wherein the sealing material is composed of rubber or PTFE (polytetrafluoroethylene).   
     
     
         13 . The air-conditioning apparatus of  claim 1 ,
 wherein the cutoff unit   is designed to accept leakage of 1.0×10 −6  (m 3 /sec) or smaller for the heat-source side refrigerant in a closed state.   
     
     
         14 . The air-conditioning apparatus of  claim 1 ,
 wherein assuming that a discharge side of the compressor is an upstream,   a value of a flow coefficient Cv is set to 5 or higher for a cutoff unit provided on a downstream side of a heat exchanger related to heat medium, among the cutoff units, and   a value of the flow coefficient Cv is set to 1 or higher for a cutoff unit provided on an upstream side of the heat exchanger related to heat medium, among the cutoff units.   
     
     
         15 . The air-conditioning apparatus of  claim 11 ,
 wherein a direct-current voltage is applied to the coil.   
     
     
         16 . The air-conditioning apparatus of  claim 15 ,
 wherein the direct-current voltage applied to the coil is within 12 (V) to 24 (V).