Refrigerant charging system and method for variable speed compressor based ac system

Abstract

The present disclosure relates to the field of air conditioning technology. In particular, it involves a refrigerant charging method for variable speed compressor based ac system.

1 . A variable speed AC charging system comprises: a variable speed compressor, a reversing valve, a thermal expansion valve, a defroster, a condenser, an inlet refrigerant temperature sensor, an outlet refrigerant temperature sensor, a suction pressure sensor, a discharge pressure sensor, a liquid line temperature sensor, outdoor air temperature sensor, defroster temperature sensor, evaporator and controller,
 wherein the AC system should be run for a predetermined time under a predetermined speed, where the speed is chosen based on AC tonnage;   wherein the controller is configured to obtain from to the various sensors of the AC system the following parameters: compressor suction pressure LP, compressor discharge pressure HP, evaporating temperature TE corresponding to the compressor suction pressure LP, condensing temperature TC corresponding to compressor discharge pressure HP;   wherein the controller is further configured to calculate compressor inlet gas superheat SH=compressor inlet gas temperature TS−evaporating temperature TE, compressor outlet superheat DSH=compressor outlet temperature TD−condensing temperature TC, and indicate whether the thermal expansion valve (TXV) is opened too much according to the compressor inlet superheat degree SH and the compressor outlet superheat degree DSH;   wherein after properly adjusting the TXV opening, the controller is further configured to determine if the AC system is properly charged.   
     
     
         2 . The variable speed AC charging system according to  claim 1 , wherein the controller is further configured to calculate outdoor heat exchanger heat transfer temperature difference ΔT=condensing temperature TC−outdoor air temperature TA, liquid line sub-cooling degree SC=condensation temperature TC−liquid line temperature TL, and refrigerant coefficient X=the liquid line sub-cooling degree SC/the outdoor heat exchanger heat transfer temperature difference ΔT, and based on the refrigerant coefficient X, determine whether the refrigerant is properly charged. 
     
     
         3 . The variable speed AC charging system according to  claim 2 , wherein the controller is configured to indicate to reduce the TXV opening when the compressor inlet gas superheat degree SH<5° F. or the compressor inlet superheat degree DSH<15° F. 
     
     
         4 . The variable speed AC charging system according to  claim 3 , wherein the controller is further configured to display the coefficient X and to indicate the refrigerant is charged correctly when the coefficient X is between Q1 and Q2, where Q1 is 0.4 and Q2 is 0.6. 
     
     
         5 . The variable speed AC charging system according to  claim 4 , wherein when the coefficient X is greater than Q2, the controller is further configured to calculate J=(condensing temperature TC−defrosting temperature TH)/outdoor heat exchanger heat transfer temperature difference ΔT, and to indicate too much refrigerant when J is greater than or equal to a value between 0.5 to 0.6 or to indicate the refrigerant is charged correctly if J is less than to that value. 
     
     
         6 . The variable speed AC charging system according to  claim 5 , wherein the controller is further configured to indicate under 0.4≤X≤0.6, whether the TXV opening degree is too small when SH≥25° F. or DSH≥60° F. 
     
     
         7 . A variable speed AC system charging method comprising:
 running the AC system for a predetermined time under a predetermined speed, where the speed is chosen based on the tonnage;   obtaining from to various sensors of the AC system the following parameters:   compressor suction pressure LP, compressor discharge pressure HP, evaporating temperature TE corresponding to the compressor suction pressure LP, condensing temperature TC corresponding to compressor discharge pressure HP;   calculating compressor inlet gas superheat SH=compressor inlet gas temperature TS−evaporating temperature TE, compressor outlet superheat DSH=compressor outlet temperature TD−condensing temperature TC;   indicating whether thermal expansion valve (TXV) is opened too much according to the compressor inlet superheat degree SH and the compressor outlet superheat degree DSH;   and after properly adjusting the TXV opening, determining if the AC system is properly charged.   
     
     
         8 . The variable speed AC system charging method according to  claim 7 , further comprising:
 calculating outdoor heat exchanger heat transfer temperature difference ΔT=condensing temperature TC−outdoor air temperature TA, liquid line sub-cooling degree SC=condensation temperature TC−liquid line temperature TL, and refrigerant coefficient X=the liquid line sub-cooling degree SC/the outdoor heat exchanger heat transfer temperature difference ΔT;   and based on the refrigerant coefficient X, determining whether the refrigerant is properly charged.   
     
     
         9 . The variable speed AC system charging method according to  claim 8 , further comprising:
 indicating to reduce the TXV opening when the compressor inlet gas superheat degree SH<5° F. or the compressor inlet superheat degree DSH<15° F.   
     
     
         10 . The variable speed AC system charging method according to  claim 9 , further comprising:
 indicating the refrigerant is charged correctly when the coefficient X is between Q1 and Q2, where Q1 is 0.4 and Q2 is 0.6.   
     
     
         11 . The variable speed AC system charging method according to  claim 10 , further comprising:
 when the coefficient X is greater than Q2, calculating J=(condensing temperature TC−defrosting temperature TH)/outdoor heat exchanger heat transfer temperature difference ΔT;   and indicating too much refrigerant when J is greater than or equal to a value between 0.5 to 0.6 or indicating the refrigerant is charged correctly if J is less than that value.   
     
     
         12 . The variable speed AC system charging method according to  claim 11 , further comprising:
 indicating under whether the TXV opening degree is too small when SH≥25° F. or DSH≥60° F.   
     
     
         13 . A non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing a first device to perform steps comprising:
 running variable speed AC system for a predetermined time under a predetermined speed, where the speed is chosen based on the tonnage;   obtaining from to various sensors of the AC system the following parameters:   compressor suction pressure LP, compressor discharge pressure HP, evaporating temperature TE corresponding to the compressor suction pressure LP, condensing temperature TC corresponding to compressor discharge pressure HP;   calculating compressor inlet gas superheat SH=compressor inlet gas temperature TS−evaporating temperature TE, compressor outlet superheat DSH=compressor outlet temperature TD−condensing temperature TC;   indicating whether thermal expansion valve (TXV) is opened too much according to the compressor inlet superheat degree SH and the compressor outlet superheat degree DSH;   and after properly adjusting the TXV opening, determining if the AC system is properly charged.   
     
     
         14 . The non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing the first device to perform steps according to  claim 13 , further comprising:
 calculating outdoor heat exchanger heat transfer temperature difference ΔT=condensing temperature TC−outdoor air temperature TA, liquid line sub-cooling degree SC=condensing temperature TC−liquid line temperature TL, and refrigerant coefficient X=the liquid line sub-cooling degree SC/the outdoor heat exchanger heat transfer temperature difference ΔT;   and based on the refrigerant coefficient X, determining whether the refrigerant is properly charged.   
     
     
         15 . The non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing the first device to perform steps according to  claim 14 , further comprising:
 indicating to reduce the TXV opening when the compressor inlet gas superheat degree SH<5° F. or the compressor inlet superheat degree DSH<15° F.   
     
     
         16 . The non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing the first device to perform steps according to  claim 15 , further comprising:
 indicating the refrigerant is charged correctly when the coefficient X is between Q1 and Q2, where Q1 is 0.4 and Q2 is 0.6.   
     
     
         17 . The non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing the first device to perform steps according to  claim 16 , further comprising:
 when the coefficient X is greater than Q2, calculating J=(condensing temperature TC−defrosting temperature TH)/outdoor heat exchanger heat transfer temperature difference ΔT;   and indicating too much refrigerant when J is greater than or equal to a value between 0.5 to 0.6 or indicating the refrigerant is charged correctly if J is less than that value.   
     
     
         18 . The non-transitory computer-readable medium having stored thereon a set of computer-executable instructions for causing the first device to perform steps according to  claim 17 , further comprising:
 indicating under 0.4≤X≤0.6, whether the TXV opening degree is too small when SH≥25° F. or DSH≥60° F.