Air-conditioning system

Abstract

An air-conditioning system includes: a load device; a heat source device; a bypass pipe; a pressure difference gauge; a bypass valve; and a controller configured to calculate a Cv value of the bypass valve when the opening degree of the bypass valve is at the full open opening degree based on the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full close opening degree and the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full open opening degree.

1 . An air-conditioning system configured to circulate a heat medium through a heat medium circuit to exchange heat between the heat medium and air in an air-conditioning target space to condition air in the air-conditioning target space, the air-conditioning system comprising:
 a load device configured to exchange heat between air in the air-conditioning target space and the heat medium flowing through the heat medium circuit;   a heat source device configured to exchange heat between refrigerant flowing through a refrigerant circuit and the heat medium flowing through the heat medium circuit, and deliver the heat medium cooled or heated through the heat medium circuit to the load device;   a first pipe that connects the heat source device and the load device and through which the heat medium flows from the heat source device to the load device;   a second pipe that connects the load device and the heat source device and through which the heat medium flows from the load device to the heat source device;   a bypass pipe connecting the first pipe with the second pipe;   a pressure difference gauge provided at the bypass pipe and configured to measure a bypass pressure difference being a pressure difference between the heat medium flowing through the first pipe and the heat medium flowing through the second pipe;   a bypass valve provided at the bypass pipe and configured to control a flow rate of the heat medium flowing through the bypass pipe; and   a controller configured to control operation of the heat source device and the bypass valve,   the controller being configured to   fix the opening degree of the bypass valve at a full close opening degree and acquire a heat source side flow rate indicating a flow rate of the heat medium flowing through the heat source device and the bypass pressure difference being measured by the pressure difference gauge, the heat source side flow rate and the bypass pressure difference being measured when the bypass valve is set at the full close opening degree,   fix the opening degree of the bypass valve at a full open opening degree, acquire the heat source side flow rate and the bypass pressure difference, the heat source side flow rate and the bypass pressure difference being measured when the opening degree of the bypass valve is at the full open opening degree, and   calculate a Cv value of the bypass valve when the opening degree of the bypass valve is at the full open opening degree based on the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full close opening degree and the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full open opening degree.   
     
     
         2 . The air-conditioning system of  claim 1 , wherein
 the load device has   a flow control valve configured to control a flow rate of the heat medium flowing through the heat medium circuit, and   while the controller calculates a Cv value of the bypass valve, an opening degree of the flow control valve is fixed.   
     
     
         3 . The air-conditioning system of  claim 1 , wherein
 the heat source device has   the refrigerant circuit formed by connecting a compressor, a heat source side heat exchanger, an expansion valve, and a heat medium heat exchanger by a refrigerant pipe, and   a pump configured to circulate the heat medium through the heat medium circuit, the heat medium exchanging heat with the refrigerant in the heat medium heat exchanger, and   the controller is configured to   fix an operating frequency of the pump, while calculating a Cv value of the bypass valve.   
     
     
         4 . The air-conditioning system of  claim 1 , further comprising a flow meter provided at the first pipe near the heat source device relative to a connection location with the bypass pipe, the flow meter being configured to measure the heat source side flow rate. 
     
     
         5 . The air-conditioning system of  claim 1 , wherein the controller is configured to
 vary an opening degree at which the bypass valve is fixed in increments of 1% from the full close opening degree, acquire the heat source side flow rate and the bypass pressure difference measured when the bypass valve is fixed at each opening degree, and   create a Cv value table in which each opening degree is associated with a Cv value of the bypass valve fixed at each opening degree based on the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full close opening degree and the bypass pressure difference and the heat source side flow rate measured when the bypass valve is fixed at each opening degree.   
     
     
         6 . The air-conditioning system of  claim 1 , wherein the controller is configured to
 calculate a Cv value gradient indicating a degree of variations in the Cv value when the opening degree of the bypass valve is varied, and control the bypass valve based on the Cv value gradient, such that the bypass pressure difference becomes a predetermined target value.   
     
     
         7 . The air-conditioning system of  claim 6 , wherein the controller is configured to
 vary an opening degree at which the bypass valve is fixed in increments of 1% from the full close opening degree, acquire the heat source side flow rate and the bypass pressure difference measured when the bypass valve is fixed at each opening degree,   create a Cv value table in which each opening degree is associated with a Cv value of the bypass valve fixed at each opening degree based on the bypass pressure difference and the heat source side flow rate measured when the bypass valve is set at the full close opening degree and the bypass pressure difference and the heat source side flow rate measured when the bypass valve is fixed at each opening degree, and   calculate the Cv value gradient based on the Cv value table.   
     
     
         8 . The air-conditioning system of  claim 6 , wherein the controller is configured to
 control the bypass valve based on the Cv value gradient when the opening degree of the bypass valve is at the full open opening degree.   
     
     
         9 . The air-conditioning system of  claim 6 , wherein the controller is configured to
 control the bypass valve based on a maximum of the Cv value gradient among the Cv value gradients, each of which is calculated from when the opening degree of the bypass valve is at the full close opening degree to when the opening degree of the bypass valve is at the full open opening degree.   
     
     
         10 . The air-conditioning system of  claim 6 , wherein the controller is configured to
 control the bypass valve based on the Cv value gradient corresponding to the opening degree of the bypass valve at a control time point.