Systems and methods for a refrigerant sub-system for a heating, ventilation, and air conditioning system

Abstract

A refrigerant sub-system includes a compressor, a condenser, an expansion valve, an evaporator, and a refrigerant-air heat exchanger. The compressor receives and compresses refrigerant. The condenser condenses the refrigerant and transfers heat from the refrigerant to a first fluid. The expansion valve expands the refrigerant. The evaporator vaporizes the refrigerant at the first pressure and transfers heat from a second fluid to the refrigerant. The refrigerant-air heat exchanger has a first operating mode and a second operating mode. In the first operating mode, the condenser is adapted to condense a first portion of the refrigerant from a vapor to a liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the refrigerant from a vapor to a liquid and transfer heat from the second portion of the refrigerant to air.

What is claimed is: 
     
         1 . A refrigerant sub-system for a heating, ventilation, and air conditioning system (HVAC), the refrigerant sub-system comprising:
 a compressor receiving uncompressed, vapor refrigerant at a first pressure, wherein the refrigerant exits the compressor as a compressed, vapor refrigerant at a second pressure higher than the first pressure;   a condenser for condensing the compressed, vapor refrigerant into a compressed, liquid refrigerant and for transferring heat from the compressed, vapor refrigerant to a first fluid;   an expansion valve for expanding the compressed, liquid refrigerant into an uncompressed, liquid refrigerant;   an evaporator for vaporizing the uncompressed, liquid refrigerant into the uncompressed, vapor refrigerant at the first pressure and transferring heat from a second fluid to the uncompressed, vapor refrigerant; and   a refrigerant-air heat exchanger having a first operating mode and a second operating mode, wherein, in the first operating mode, the condenser is adapted to condense a first portion of the compressed, vapor refrigerant from a vapor to a liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the compressed, vapor refrigerant from a vapor to a liquid and transfer heat from the second portion of the compressed, vapor refrigerant to air.   
     
     
         2 . The refrigerant sub-system of  claim 1 , wherein, in a second operating mode, the evaporator is adapted to vaporize a first portion of the uncompressed, liquid refrigerant from a liquid to a vapor, and the refrigerant-air heat exchanger is adapted to vaporize a second portion of the uncompressed, liquid refrigerant from a liquid to a vapor and transfer heat from the air to the second portion of the uncompressed, liquid refrigerant. 
     
     
         3 . The refrigerant sub-system of  claim 2 , wherein the at least one expansion valve includes a first expansion valve and a second expansion valve, and wherein, in the first operating mode, the first expansion valve expands the compressed, liquid refrigerant into the uncompressed, liquid refrigerant. 
     
     
         4 . The refrigerant sub-system of  claim 3 , further comprising a check valve disposed for bypassing the second expansion valve, and wherein, in the first operating mode, the check valve channels a first portion of the compressed, liquid refrigerant around the second expansion valve. 
     
     
         5 . The refrigerant sub-system of  claim 3 , wherein, in the second operating mode, the first expansion valve controls the first portion of the uncompressed, liquid refrigerant to the evaporator and the second expansion valve controls the second portion of the uncompressed, liquid refrigerant to the refrigerant-air heat exchanger. 
     
     
         6 . The refrigerant sub-system of  claim 4 , further comprising a first on/off valve and a second on/off valve, and wherein, in the first operating mode, the first on/off valve is open to channel the second portion of the compressed, vapor refrigerant from the compressor to the refrigerant-air heat exchanger, and the second on/off valve is closed. 
     
     
         7 . The refrigerant sub-system of  claim 6 , wherein, in the second operating mode, the second on/off valve is open to channel a second portion of the uncompressed, vapor refrigerant from the refrigerant-air heat exchanger to the compressor, and the first on/off valve is closed. 
     
     
         8 . The refrigerant sub-system of  claim 6 , wherein the first and second on/off valves are solenoid valves. 
     
     
         9 . The refrigerant sub-system of  claim 6 , wherein the first and second expansion valves are thermal expansion valves. 
     
     
         10 . The refrigerant sub-system of  claim 6 , wherein the refrigerant-air heat exchanger is a refrigerant-air coil. 
     
     
         11 . A heating, ventilation, and air conditioning (HVAC) system, the HVAC system comprising:
 a hot water sub-system for circulating a flow of a first fluid;   a cold water sub-system for circulating a flow of a second fluid; and   a refrigerant sub-system for transferring heat from the cold water sub-system to the hot water sub-system and the environment, the refrigerant sub-system comprising:
 a compressor receiving uncompressed, vapor refrigerant at a first pressure, wherein the refrigerant exits the compressor as a compressed, vapor refrigerant at a second pressure higher than the first pressure; 
 a condenser for condensing the compressed, vapor refrigerant into a compressed, liquid refrigerant and for transferring heat from the compressed, vapor refrigerant to the first fluid; 
 an expansion valve for expanding the compressed, liquid refrigerant into an uncompressed, liquid refrigerant; 
 an evaporator for vaporizing the uncompressed, liquid refrigerant into the uncompressed, vapor refrigerant at the first pressure and transferring heat from the second fluid to the uncompressed, vapor refrigerant; and 
 a refrigerant-air heat exchanger having a first operating mode and a second operating mode, wherein, in the first operating mode, the condenser is adapted to condense a first portion of the compressed, vapor refrigerant from a vapor to a liquid, and the refrigerant-air heat exchanger is adapted to condense a second portion of the compressed, vapor refrigerant from a vapor to a liquid and transfer heat from the second portion of the compressed, vapor refrigerant to air. 
   
     
     
         12 . The HVAC system of  claim 11 , wherein the hot water sub-system includes the condenser, a first pump, and a first heat exchanger, wherein the first pump receives the flow of the first fluid from the first heat exchanger and pumps the flow of the first fluid to the condenser. 
     
     
         13 . The HVAC system of  claim 12 , wherein the cold water sub-system includes the evaporator, a second pump, and a second heat exchanger, wherein the second pump receives the flow of the second fluid from the second heat exchanger and pumps the flow of the second fluid to the evaporator. 
     
     
         14 . The HVAC system of  claim 13 , wherein the first and second heat exchangers transfer moisture and heat between a third fluid and air, the first heat exchanger transfers heat from the first fluid to the third fluid and the air, the second heat exchanger transfers heat from the third fluid and the air to the second fluid. 
     
     
         15 . The HVAC system of  claim 14 , wherein the first and second fluids are water, and the third fluid is a liquid desiccant. 
     
     
         16 . A method of transferring heat from a cold water sub-system of a heating, ventilation, and air conditioning (HVAC) system to a hot water sub-system of the HVAC system using a refrigerant sub-system, the refrigerant sub-system includes a compressor, a condenser, an evaporator, an expansion valve, and a refrigerant-air heat exchanger, the method comprising:
 compressing an uncompressed, vapor refrigerant at a first pressure into a compressed, vapor refrigerant at a second pressure higher than the first pressure using the compressor;   condensing the compressed, vapor refrigerant into a compressed, liquid refrigerant and transferring heat from the compressed, vapor refrigerant to a first fluid using the condenser;   expanding the compressed, liquid refrigerant into an uncompressed, liquid refrigerant using the expansion valve;   vaporizing the uncompressed, liquid refrigerant into the uncompressed, vapor refrigerant at the first pressure and transferring heat from a second fluid to the uncompressed, vapor refrigerant using the evaporator; and   condensing, in a first operating mode, a first portion of the compressed, vapor refrigerant from a vapor to a liquid using the condenser, and condensing a second portion of the compressed, vapor refrigerant from a vapor to a liquid and transferring heat from the second portion of the compressed, vapor refrigerant to air using the refrigerant-air heat exchanger.   
     
     
         17 . The method of  claim 16  further comprising, in a second operating mode, vaporizing a first portion of the uncompressed, liquid refrigerant from a liquid to a vapor using the evaporator, and vaporizing a second portion of the uncompressed, liquid refrigerant from a liquid to a vapor and transferring heat from the air to the second portion of the uncompressed, liquid refrigerant using the refrigerant-air heat exchanger. 
     
     
         18 . The method of  claim 17 , wherein the expansion valve includes a first expansion valve and a second expansion valve, the method further comprising, in the first operating mode, expanding the compressed, liquid refrigerant into the uncompressed, liquid refrigerant using the first expansion valve. 
     
     
         19 . The method of  claim 18  further comprising, in the second operating mode, controlling the first portion of the uncompressed, liquid refrigerant to the evaporator using the first expansion valve and controlling the second portion of the uncompressed, liquid refrigerant to the refrigerant-air heat exchanger using the second expansion valve. 
     
     
         20 . The method of  claim 18 , wherein the refrigerant sub-system further includes a check valve that bypasses the second expansion valve, the method further comprising, in the first operating mode, channeling a first portion of the compressed, liquid refrigerant around the second expansion valve using the check valve.