Modular chiller

Abstract

A high capacity, modular chiller system is capable of multiple modes of operation, including a dedicated cooling mode, a dedicated heating mode, and a simultaneous heating and cooling mode, among others, without changing direction of the refrigerant through the expansion valve for any of the operating modes. In a frost mitigation operating mode, a portion of the refrigerant leaving the compressor is routed upstream of the air-source heat exchanger to avoid having to reverse the direction of refrigerant flow and to avoid ceasing generation of heated water by the load heat exchanger to thaw the air-source heat exchanger. The modular chiller system may include a vapor injection circuit for increased heating capacity. The modular chiller system may be coupled with a pipe header for ease of installation and to maximize modularity and capacity by arranging in a bank of chiller units.

What is claimed is: 
     
         1 . A chiller system, comprising:
 a refrigerant circuit through which a refrigerant is configured to flow;   a compressor disposed on the refrigerant circuit, the compressor including a compressor inlet, a compressor outlet, and a vapor injection inlet disposed between the compressor inlet and the compressor outlet;   a first load heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a first load, the first load heat exchanger having an active state and an inactive state and operable as a condenser or an evaporator;   a second load heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a second load, the second load heat exchanger having an active state and an inactive state and operable as the evaporator;   a source heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a source, the source heat exchanger the first load heat exchanger having an active state and an inactive state and operable as the condenser or the evaporator;   a reversing valve disposed on the refrigerant circuit and including a first port connected to a pressure side of the compressor, a second port connected to the first load heat exchanger, a third port connected to the source heat exchanger, and a fourth port connected to a suction side of the compressor;   a receiver positioned downstream of the first load heat exchanger and configured to act as a reservoir for the refrigerant; and   an expansion valve positioned (i) between the receiver and the source heat exchanger when the chiller system is configured to operate in a first operating mode, (ii) between the source heat exchanger and the second load heat exchanger when the chiller system is configured to operate in a second operating mode, (iii) between the source heat exchanger and the first load heat exchanger when the chiller system is configured to operate in a third operating mode, and (iv) between the receiver and the second load heat exchanger when the chiller system is configured to operate in a fourth operating mode.   
     
     
         2 . The chiller system of  claim 1 , wherein the compressor is a variable speed compressor. 
     
     
         3 . The chiller system of  claim 1 , including an intermediate evaporator and an intermediate evaporator expansion valve disposed on a vapor injection circuit that is connected to the refrigerant circuit, wherein
 a first portion of the refrigerant is diverted from the refrigerant circuit downstream of the first load heat exchanger to the intermediate evaporator expansion valve, and   the diverted first portion of the refrigerant leaving the intermediate evaporator expansion valve is directed to the intermediate evaporator to exchange heat with a second portion of the refrigerant in the refrigerant circuit to vaporize the diverted first portion of the refrigerant for entry into the vapor injection inlet of the compressor.   
     
     
         4 . The chiller system of  claim 3 , wherein the intermediate evaporator expansion valve controls an amount of the first portion of the refrigerant that is diverted from the refrigerant circuit to the vapor injection circuit. 
     
     
         5 . The chiller system of  claim 4 , wherein the amount of the first portion ranges from 10% to 25%. 
     
     
         6 . The chiller system of  claim 1 , wherein the reversing valve is configured to route the refrigerant to the compressor, the first load heat exchanger, and the source heat exchanger and to receive the refrigerant from the compressor, the source heat exchanger, and the first load heat exchanger. 
     
     
         7 . The chiller system of  claim 1 , including a first check valve positioned between the receiver and the expansion valve, wherein the first check valve allows the refrigerant to flow from the receiver to the expansion valve and inhibits flow of the refrigerant from the expansion valve to the receiver. 
     
     
         8 . The chiller system of  claim 7 , including a second check valve disposed between the expansion valve and the source heat exchanger, wherein the second check valve allows the refrigerant to flow from the expansion valve to the source heat exchanger and inhibits flow of the refrigerant from the source heat exchanger to the expansion valve. 
     
     
         9 . The chiller system of  claim 8 , including a third check valve disposed on a branch circuit connected to the refrigerant circuit, wherein the third check valve is disposed between the expansion valve and the source heat exchanger, wherein the third check valve allows the refrigerant to flow from the source heat exchanger to the expansion valve and inhibits flow of the refrigerant from the expansion valve to the source heat exchanger. 
     
     
         10 . The chiller system of  claim 9 , including a fourth check valve disposed on a defrost circuit connected to the refrigerant circuit, wherein the fourth check valve is disposed between the expansion valve and the first load heat exchanger, wherein the fourth check valve allows the refrigerant to flow from the expansion valve to the first load heat exchanger and inhibits flow of the refrigerant from the first load heat exchanger to the expansion valve. 
     
     
         11 . The chiller system of  claim 1 , including a first solenoid valve disposed on a bypass circuit that is connected to the refrigerant circuit, wherein
 the bypass circuit is positioned between the compressor and the expansion valve, and   when the first solenoid valve is open, a first portion of the refrigerant leaving the compressor is diverted to the first solenoid valve and then merged with a second portion of the refrigerant in the refrigerant circuit at a location downstream of the expansion valve and upstream of the source heat exchanger.   
     
     
         12 . The chiller system of  claim 11 , including a second solenoid valve disposed on a defrost circuit that is connected to the refrigerant circuit, wherein the defrost circuit is positioned between the expansion valve and the first load heat exchanger. 
     
     
         13 . The chiller system of  claim 12 , including a controller comprising a processor and memory and configured to control operation of the compressor, the reversing valve, the expansion valve, the first load heat exchanger, the second load heat exchanger, and the source heat exchanger. 
     
     
         14 . The chiller system of  claim 13 , wherein the first operating mode is a heating mode, and in the heating mode the controller is configured to:
 control the reversing valve to receive the refrigerant from the compressor and direct the refrigerant to the first load heat exchanger acting as the condenser;   close the first solenoid valve to inhibit flow of the refrigerant to the bypass circuit;   close the second solenoid valve to inhibit flow of the refrigerant to the defrost circuit;   close a third solenoid valve to inactivate the second load heat exchanger;   open a fourth solenoid valve to direct the refrigerant from the expansion valve to the source heat exchanger acting as the evaporator; and   control the reversing valve to receive the refrigerant leaving the source heat exchanger and direct the refrigerant to the compressor.   
     
     
         15 . The chiller system of  claim 13 , wherein in a heating and frost mitigation mode, the controller is configured to:
 control the reversing valve to receive the refrigerant from the compressor and direct the refrigerant to the first load heat exchanger acting as the condenser;   open the first solenoid valve to divert the first portion of the refrigerant leaving the compressor to the first solenoid valve along the bypass circuit, wherein the first portion of the refrigerant is merged with the second portion of the refrigerant and merged with the second portion of the refrigerant in the refrigerant circuit at the location downstream of the expansion valve and upstream of the source heat exchanger;   close the second solenoid valve to inhibit flow of the refrigerant to the defrost circuit;   close a third solenoid valve to inactivate the second load heat exchanger;   open a fourth solenoid valve to direct the refrigerant from the expansion valve to the source heat exchanger acting as the evaporator; and   control the reversing valve to receive the refrigerant leaving the source heat exchanger and direct the refrigerant to the compressor.   
     
     
         16 . The chiller system of  claim 13 , wherein the second operating mode is a cooling mode, and in the cooling mode the controller is configured to:
 control the reversing valve to receive the refrigerant from the compressor and direct the refrigerant to the source heat exchanger acting as the condenser;   close the first solenoid valve to inhibit flow of the refrigerant to the bypass circuit;   close the second solenoid valve to inhibit flow of the refrigerant to the defrost circuit; and   open a third solenoid valve and close a fourth solenoid valve to direct the refrigerant from the expansion valve to the second load heat exchanger acting as the evaporator,   wherein the refrigerant leaving the second load heat exchanger is returned to the compressor.   
     
     
         17 . The chiller system of  claim 13 , wherein the third operating mode is a cooling and defrost mode, and in the cooling and defrost mode the controller is configured to:
 control the reversing valve to receive the refrigerant from the compressor and direct the refrigerant to the source heat exchanger acting as the condenser;   close the first solenoid valve to inhibit flow of the refrigerant to the bypass circuit;   open the second solenoid valve to direct the refrigerant to the defrost circuit; and   close a third solenoid valve and close a fourth solenoid valve to direct the refrigerant from the expansion valve to the second solenoid valve, and from the second solenoid valve to the first load heat exchanger acting as the evaporator,   wherein the refrigerant leaving the first load heat exchanger is direct to the reversing valve, which directs the refrigerant to the compressor.   
     
     
         18 . The chiller system of  claim 13 , wherein the fourth operating mode is a simultaneous heating and cooling mode, and in the simultaneous heating and cooling mode the controller is configured to:
 control the reversing valve to receive the refrigerant from the compressor and direct the refrigerant to the first load heat exchanger acting as the condenser;   close the first solenoid valve to inhibit flow of the refrigerant to the bypass circuit;   close the second solenoid valve to inhibit flow of the refrigerant to the defrost circuit; and   open a third solenoid valve and close a fourth solenoid valve to direct the refrigerant from the expansion valve to the second load heat exchanger acting as the evaporator, thereby inactivating the source heat exchanger,   wherein the refrigerant leaving the second load heat exchanger is returned to the compressor.   
     
     
         19 . A chiller system, comprising:
 a refrigerant circuit through which a refrigerant is configured to flow;   a defrost circuit connected to the refrigerant circuit through which the refrigerant is configured to flow when the chiller system is in a defrost operating mode;   a source heat exchanger frost mitigation circuit connected to the refrigerant circuit through which a first portion of the refrigerant is configured to flow when the chiller system is in a source heat exchanger frost mitigation operating mode;   a variable speed compressor disposed on the refrigerant circuit, the compressor including a compressor inlet, a compressor outlet, and a vapor injection inlet disposed between the compressor inlet and the compressor outlet;   a vapor injection circuit connected to the refrigerant circuit through which a second portion of the refrigerant is configured to flow, the vapor injection circuit configured to vaporize the second portion of the refrigerant and direct the vaporized second portion of the refrigerant circuit to the vapor injection inlet of the compressor;   a refrigerant-to-water first load heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a first load, the first load heat exchanger having an active state and an inactive state and operable as a condenser or an evaporator;   a refrigerant-to-water second load heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a second load, the second load heat exchanger having an active state and an inactive state and operable as the evaporator;   a refrigerant-to-air source heat exchanger disposed on the refrigerant circuit to exchange heat between the refrigerant and a source, the source heat exchanger the first load heat exchanger having an active state and an inactive state and operable as the condenser or the evaporator;   a reversing valve disposed on the refrigerant circuit and including a first port connected to a pressure side of the compressor, a second port connected to the first load heat exchanger, a third port connected to the source heat exchanger, and a fourth port connected to a suction side of the compressor; and   an expansion valve positioned (i) between the first load heat exchanger and the source heat exchanger when the chiller system is configured to operate in a first operating mode, (ii) between the source heat exchanger and the second load heat exchanger when the chiller system is configured to operate in a second operating mode, (iii) between the source heat exchanger and the first load heat exchanger when the chiller system is configured to operate in a third operating mode, and (iv) between the first load heat exchanger and the second load heat exchanger when the chiller system is configured to operate in a fourth operating mode;   wherein a direction of flow of the refrigerant through the expansion valve for the first operating mode is identical to the direction of flow of the refrigerant through the expansion valve for the second operating mode, the third operating mode and the fourth operating mode.   
     
     
         20 . The chiller system of  claim 19 , including a controller comprising a processor and memory and configured to control operation of the compressor, the reversing valve, the expansion valve, the first load heat exchanger, the second load heat exchanger, and the source heat exchanger.