Refrigerating and air-conditioning system and system controller

Abstract

A refrigerating and air-conditioning system includes a plurality of independent refrigerating and air-conditioning apparatuses each including a refrigerant circuit and a defrosting unit, and further includes a system controller managing the apparatuses in an integrative manner. The system controller includes a defrosting operation control unit. When a time interval between an estimated defrosting start time calculated for a given refrigerating and air-conditioning apparatus and a subsequent estimated defrosting start time calculated for another refrigerating and air-conditioning apparatus is less than or equal to a predetermined target start time interval, the defrosting operation control unit transmits a defrosting start instruction signal to the defrosting unit of the given refrigerating and air-conditioning apparatus.

1 . A refrigerating and air-conditioning system comprising:
 a plurality of refrigerating and air-conditioning apparatuses provided independent of each other and each of which includes a refrigerant circuit in which a compressor, a condenser, an expansion valve and an evaporator are connected, and each of which detects an operation state of the refrigerant circuit, and removes frost forming on the evaporator; and   a system controller configured to manage operations of the plurality of refrigerating and air-conditioning apparatuses in an integrative manner,   the system controller being configured to:
 calculate an estimated defrosting start time, at which a defrosting operation to remove the frost forming on the evaporator is to be started, for each of the plurality of refrigerating and air-conditioning apparatuses, based on the operation state of the refrigerant circuit of the each of the plurality of refrigerating and air-conditioning apparatuses control the defrosting operation based on the estimated defrosting start time; and 
 cause the defrosting operation of one of the plurality of refrigerating and air-conditioning apparatuses to start earlier than the estimated defrosting start time, in a case where a time interval between the estimated defrosting start time for the one of the plurality of refrigerating and air-conditioning apparatuses and the estimated defrosting start time for an other one of the plurality of refrigerating and air-conditioning apparatuses is less than or equal to a predetermined time interval. 
   
     
     
         2 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein the system controller is configured to:   calculate an accumulated cooling-operation duration which is to increase until start of defrosting of the each of the plurality of refrigerating and air-conditioning apparatuses and a cooling operation availability of the each of the plurality of refrigerating and air-conditioning apparatuses; and   calculate the estimated defrosting start time for the each of the plurality of refrigerating and air-conditioning apparatuses based on the accumulated cooling-operation duration and the cooling operation availability.   
     
     
         3 . The refrigerating and air-conditioning system of  claim 1 , wherein the evaporators of the plurality of refrigerating and air-conditioning apparatuses are disposed in a single target space to be cooled. 
     
     
         4 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein the plurality of refrigerating and air-conditioning apparatuses each detect frost forming on a refrigerant tube for the evaporator, and   wherein the system controller is configured to calculate the estimated defrosting start time for the each of the plurality of refrigerating and air-conditioning apparatuses based on a degree of formation of the frost detected by the plurality of refrigerating and air-conditioning apparatuses.   
     
     
         5 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein the plurality of refrigerating and air-conditioning apparatuses each detect a temperature of refrigerant at an inlet of the evaporator and a temperature of the refrigerant at an outlet of the evaporator, and   wherein the system controller is configured to calculate the estimated defrosting start time for the each of the plurality of refrigerating and air-conditioning apparatuses based on the temperature of the refrigerant at the inlet of the evaporator and the temperature of the refrigerant at the outlet of the evaporator, which are both detected by the plurality of refrigerating and air-conditioning apparatuses.   
     
     
         6 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein the plurality of refrigerating and air-conditioning apparatuses each detect a rotation speed of a fan configured to send air to the evaporator, and   wherein the system controller is configured to calculate the estimated defrosting start point for the each of the plurality of refrigerating and air-conditioning apparatuses based on a change of the rotation speed of the fan which is made with passage of time, the rotation speed of the fan being detected by the plurality of refrigerating and air-conditioning apparatuses.   
     
     
         7 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein plurality of refrigerating and air-conditioning apparatuses each detect a temperature of refrigerant at an inlet of the evaporator, a temperature of air on a suction side of the evaporator, and the temperature of the air on a discharge side of the evaporator, and   wherein the system controller is configured to calculate the estimated defrosting start time for the each of the plurality of refrigerating and air-conditioning apparatuses based on a change of the temperature of the refrigerant at the inlet of the evaporator which is made with passage of time, a change of the temperature of the air on the suction side of the evaporator which is made with passage of time, and a change of the temperature of the air on the discharge side of the evaporator which is made with passage of time, the temperature of the refrigerant at the inlet of the evaporator, the temperature of the air on the suction side of the evaporator and the temperature of the air on the discharge side of the evaporator being all detected by the plurality of refrigerating and air-conditioning apparatuses.   
     
     
         8 . The refrigerating and air-conditioning system of  claim 1 ,
 wherein with respect to ones of the plurality of refrigerating and air-conditioning apparatuses, for which at least one interval between estimated defrosting start times of the ones of the plurality of refrigerating and air-conditioning apparatuses is shorter than or equal to a predetermined time interval, the system controller prepares operation patterns in each of which the ones of the plurality of refrigerating and air-conditioning apparatuses are arbitrarily combined to simultaneously perform defrosting operation, and selects one of the operation patterns based on a system capacity of the refrigerating and air-conditioning apparatus at time of applying each of the operation patterns and a cooling capacity required for the plurality of refrigerating and air-conditioning apparatuses.   
     
     
         9 . A system controller configured to manage in an integrative manner a plurality of refrigerating and air-conditioning apparatuses provided independent of each other and each of which includes a refrigerant circuit in which a compressor, a condenser, an expansion valve and an evaporator are connected, and each of which detects an operation state of the refrigerant circuit, and removes frost formed on the evaporator,
 the system controller being configured to:
 calculate an estimated defrosting start time, at which a defrosting operation to remove the frost formed on the evaporator is to be started, for each of the plurality of refrigerating and air-conditioning apparatuses, based on the operation state of the refrigerant circuit of the each of the plurality of refrigerating and air-conditioning apparatuses, and control the defrosting operation based on the estimated defrosting start time; and 
 cause the defrosting operation of one of the plurality of refrigerating and air-conditioning apparatuses to start earlier than the estimated defrosting start time, in a case where a time interval between the estimated defrosting start time for the one of the plurality of refrigerating and air-conditioning apparatuses and the estimated defrosting start time for an other one of the plurality of refrigerating and air-conditioning apparatuses is less than or equal to a predetermined time interval.