Heat pump system with flash defrosting mode

Abstract

A heat pump system is provided, comprising: a cooling and heating coil having first and second refrigerant ports; a reheat coil having third and fourth refrigerant ports; first and second refrigerant pipes connected to the first and second refrigerant ports, respectively; a first solenoid valve between the third refrigerant port and the second refrigerant pipe; a second solenoid valve between the fourth refrigerant port and the second refrigerant line; an expansion valve between the fourth refrigeration port and the second refrigerant port; a first check valve between the fourth refrigerant port and the expansion valve; a second check valve between the expansion valve and a condensing circuit; a third check valve between the first check valve and the expansion valve; a fan circuit for blowing air across the cooling and heating coil and the reheat coil in order; and a controller for controlling the heat pump system.

1 . A heat pump system comprising:
 a cooling and heating coil having a first refrigerant port and a second refrigerant port and configured to circulate refrigerant;   a reheat coil having a third refrigerant port and a fourth refrigerant port and configured to circulate the refrigerant;   a plurality of refrigerant pipes configured to circulate the refrigerant, the plurality of refrigerant pipes including
 a first refrigerant pipe connected between the first refrigerant port and a condensing circuit, 
 a second refrigerant pipe connected between the second refrigerant port and the condensing circuit, 
 a third refrigerant pipe connected between the third refrigerant port and a first node on the second refrigerant pipe, 
 a fourth refrigerant pipe connected between the fourth refrigerant port and a second node on the third refrigerant pipe, and 
 a fifth refrigerant pipe connected between a third node on the fourth refrigerant pipe and a fourth node on the second refrigerant pipe; 
   a first solenoid valve formed on the third refrigerant pipe between the third refrigerant port and the second node;   a second solenoid valve formed on the fourth refrigerant pipe between the second node and the third node;   an expansion valve connected between the second refrigerant port and the fourth node;   a first check valve connected between the fourth refrigerant port and the third node and configured to prevent flow of the refrigerant from the third node to the fourth refrigerant port;   a second check valve connected between the first node and the fourth node and configured to prevent flow of the refrigerant from the first node to the fourth node;   a third check valve connected between the third node and the fourth node and configured to prevent flow of the refrigerant from the fourth node to the third node;   a fan circuit configured to blow input air across the cooling and heating coil to generate discharge air and to blow the discharge air over the reheat coil to generate supply air; and   a controller configured to control the heat pump system.   
     
     
         2 . The heat pump system of  claim 1 , wherein the expansion valve is an electronically controlled expansion valve. 
     
     
         3 . The heat pump system of  claim 1 , wherein the first solenoid valve is a positive off solenoid valve. 
     
     
         4 . The heat pump system of  claim 1 , wherein the second solenoid valve is a positive off solenoid valve. 
     
     
         5 . A method for operating a heat pump system to defrost a condenser coil, the method comprising:
 maintaining refrigerant in a reheat coil without circulating the refrigerant through the reheat coil during a heating mode;   circulating refrigerant through a cooling and heating coil during the heating mode;   blowing input air across the cooling and heating coil during the heating mode to generate discharge air, the discharge air in the heating mode being warmer than the input air;   blowing the discharge air over the reheat coil during the heating mode to generate supply air;   circulating refrigerant from the reheat coil to the cooling and heating coil after entering a defrost mode; and   circulating refrigerant from the cooling and heating coil to the condenser coil during the defrost mode.   
     
     
         6 . The method of  claim 5 , further comprising:
 stopping blowing the input air across the cooling and heating coil and stopping blowing the discharge air over the reheat coil after entering a defrost mode.   
     
     
         7 . The method of  claim 5 , further comprising 
 stopping blowing the input air across the cooling and heating coil and stopping blowing the discharge air over the reheat coil in response to entering the defrost mode, wherein   the circulating of the refrigerant from the reheat coil to the cooling and heating coil is performed after the stopping of blowing the input air across the cooling and heating coil and the stopping of blowing the discharge air over the reheat coil, and   the circulating of the refrigerant from the cooling and heating coil to the condenser coil is performed after the stopping of blowing the input air across the heating and cooling coil and the stopping of blowing the discharge air over the reheat coil.   
     
     
         8 . The method of  claim 5 , wherein the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by opening a first solenoid valve and closing a second solenoid valve. 
     
     
         9 . The method of  claim 5 , further comprising 
 receiving from a controller a signal indicating a start of a defrosting mode prior to entering the defrost mode.   
     
     
         10 . The method of  claim 5 , further comprising:
 receiving a signal from a controller indicating an end of a defrosting mode and a resumption of the heating mode; and   stopping circulating refrigerant from the reheat coil to the cooling and heating coil after the defrosting mode has ended and the heating mode has resumed.   
     
     
         11 . The method of  claim 10 , wherein 
 the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by opening a first solenoid valve and closing a second solenoid valve; and   the stopping of the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by closing the first solenoid valve and opening the second solenoid valve.   
     
     
         12 . The method of  claim 10 , further comprising:
 resuming blowing input air across the cooling and heating coil to generate discharge air after the defrosting mode has ended and the heating mode has resumed;   resuming blowing the discharge air over the reheat coil to generate supply air after the defrosting mode has ended and the heating mode has resumed.   
     
     
         13 . A non-transitory computer-readable medium comprising instructions for execution by a computer, the instructions including a computer-implemented method for controlling a heat pump system to defrost a condenser coil, the instructions for implementing:
 maintaining refrigerant in a reheat coil without circulating the refrigerant through the reheat coil during a heating mode;   circulating refrigerant through a cooling and heating coil during the heating mode;   blowing input air across the cooling and heating coil during the heating mode to generate discharge air, the discharge air in the heating mode being warmer than the input air;   blowing the discharge air over the reheat coil during the heating mode to generate supply air;   circulating refrigerant from the reheat coil to the cooling and heating coil after entering a defrost mode; and   circulating refrigerant from the cooling and heating coil to the condenser coil during the defrost mode.   
     
     
         14 . The non-transitory computer-readable medium, as recited in  claim 13 , the instructions for further implementing:
 stopping blowing the input air across the cooling and heating coil and stopping blowing the discharge air over the reheat coil after entering a defrost mode.   
     
     
         15 . The non-transitory computer-readable medium, as recited in  claim 13 , the instructions for further implementing:
 stopping blowing the input air across the cooling and heating coil and stopping blowing the discharge air over the reheat coil in response to entering the defrost mode, wherein   the circulating of the refrigerant from the reheat coil to the cooling and heating coil is performed after the stopping of blowing the input air across the cooling and heating coil and the stopping of blowing the discharge air over the reheat coil, and   the circulating of the refrigerant from the cooling and heating coil to the condenser coil is performed after the stopping of blowing the input air across the cooling and heating coil and the stopping of blowing the discharge air over the reheat coil.   
     
     
         16 . The non-transitory computer-readable medium, as recited in  claim 13 , wherein the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by opening a first solenoid valve and closing a second solenoid valve. 
     
     
         17 . The non-transitory computer-readable medium, as recited in  claim 13 , the instructions for further implementing:
 exiting the defrosting mode and resuming the heating mode; and   stopping circulating refrigerant from the reheat coil to the cooling and heating coil after the defrosting mode has ended and the heating mode has resumed.   
     
     
         18 . The non-transitory computer-readable medium, as recited in  claim 17 , wherein
 the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by opening a first solenoid valve and closing a second solenoid valve; and   the stopping of the circulating of the refrigerant from the reheat coil to the cooling and heating coil is achieved by closing the first solenoid valve and opening the second solenoid valve.   
     
     
         19 . The non-transitory computer-readable medium, as recited in  claim 17 , the instructions for further implementing:
 resuming blowing input air across the cooling and heating coil to generate discharge air after the defrosting mode has ended and the heating mode has resumed; and   resuming blowing the discharge air over the reheat coil to generate supply air after the defrosting mode has ended and the heating mode has resumed.