Improved dircet expansion evaporator based chiller system

Abstract

A chiller system is provided including a vapor compression circuit consisting of a fluidly coupled compressor, condenser, expansion valve, and evaporator. A refrigerant circulates through the vapor compression circuit. The evaporator is a direct exchange heat exchanger. Refrigerant provided at an outlet of the evaporator is a two-phase mixture including liquid refrigerant and vapor refrigerant. The vapor refrigerant comprises less than or equal to 85% of the two-phase mixture. A refrigerant to refrigerant heat exchanger is fluidly coupled to the circuit. The refrigerant to refrigerant heat exchanger is configured to convert the vapor refrigerant provided at the outlet of the evaporator into a superheated vapor.

1 . A chiller system comprising:
 a vapor compression circuit including a compressor, a condenser, an expansion valve, and an evaporator fluidly coupled and having a refrigerant circulating there through, the evaporator being a direct exchange heat exchanger such that the refrigerant provided at an outlet of the evaporator is a two-phase mixture of liquid refrigerant and vapor refrigerant, and the vapor refrigerant comprises less than or equal to about 85% of the two-phase mixture; and   a refrigerant to refrigerant heat exchanger fluidly coupled to the circuit, the refrigerant to refrigerant heat exchanger being configured to convert the vapor refrigerant provided at the outlet of the evaporator into a superheated vapor.   
     
     
         2 . The chiller system according to  claim 1 , wherein the refrigerant has a low global warming potential. 
     
     
         3 . The chiller system according to  claim 2 , wherein the refrigerant includes at least one of a Hydrofluoroolefin (HFO) or an HFO blend. 
     
     
         4 . The chiller system according to  claim 1 , further comprising a lubrication system including an oil separator arranged generally downstream from the compressor, the oil separator being configured to supply oil separated from the refrigerant to one or more moving components of the compressor. 
     
     
         5 . The chiller system according to  claim 4 , wherein the oil is an immiscible oil. 
     
     
         6 . A chiller system comprising:
 a vapor compression circuit including a compressor, a condenser, an expansion valve, and an evaporator fluidly coupled and having a refrigerant circulating there through, the evaporator being a direct exchange heat exchanger such that the refrigerant provided at an outlet of the evaporator is a two-phase mixture of liquid refrigerant and vapor refrigerant, and the vapor refrigerant comprises less than or equal to about 85% of the two-phase mixture; and   an efficiency circuit including a separator configured to separate the two-phase mixture into liquid refrigerant and vapor refrigerant, the efficiency circuit being operably coupled to the outlet of the evaporator and configured to recirculate liquid refrigerant from the separator through the evaporator to improve the efficiency of the chiller system.   
     
     
         7 . The chiller system according to  claim 6 , wherein the refrigerant has a low global warming potential. 
     
     
         8 . The chiller system according to  claim 7 , wherein the refrigerant includes an HFO. 
     
     
         9 . The chiller system according to  claim 6 , further comprising a lubrication system including an oil separator arranged generally downstream from the compressor, the oil separator being configured to supply oil separated from the refrigerant to one or more moving components of the compressor. 
     
     
         10 . The chiller system according to  claim 9 , wherein the oil is immiscible oil. 
     
     
         11 . The chiller system according to  claim 6 , wherein the separator is operably coupled to the compressor and is configured to supply vapor refrigerant thereto. 
     
     
         12 . The chiller system according to  claim 11 , wherein the efficiency circuit further includes an ejector having a first inlet and a second inlet, the ejector being positioned generally downstream from the condenser and upstream from the separator. 
     
     
         13 . The chiller system according to  claim 12 , wherein a first outlet of the separator is operably coupled to the second inlet of the ejector and is configured to supply liquid refrigerant thereto. 
     
     
         14 . The chiller system according to  claim 13 , wherein the separator is arranged generally downstream from the evaporator and upstream from the compressor. 
     
     
         15 . The chiller system according to  claim 14 , wherein the ejector is positioned generally upstream from the expansion device. 
     
     
         16 . The chiller system according to  claim 12 , wherein the outlet of the evaporator is operably coupled to the second inlet of the ejector. 
     
     
         17 . The chiller system according to  claim 16 , wherein the separator is arranged generally downstream of the ejector and generally upstream from the expansion device. 
     
     
         18 . The chiller system according to  claim 6 , further comprising:
 a refrigerant to refrigerant heat exchanger fluidly coupled to the vapor compression circuit and the efficiency circuit, the refrigerant to refrigerant heat exchanger being configured to convert the vapor refrigerant provided from an outlet of the separator into a superheated vapor.