High efficiency air conditioning systems and methods

Abstract

Disclosed are refrigeration systems of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system preferably having a capacity of from about 2 to about 30 tons and comprising: (a) a heat transfer composition comprising a refrigerant comprising at least about 80% by weight of trans1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) or at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (HFO-1234ze(E)); (b) a centrifugal compressor having: (i) a refrigerant suction for receiving a relatively low-pressure refrigerant vapor at a pressure of from about 40 to about 350 kPa and (ii) a discharge for discharging a relatively high pressure refrigerant vapor at a pressure wherein the discharge:suction pressure ratio is at least about 2:1; (c) a condenser operating at temperature in the range of from about 10° C. to about 60° C.; (d) and expander for producing relatively cold low pressure refrigerant liquid; (e) a high efficiency evaporator, preferably a flooded evaporator, fluidly connected to said expander for receiving said low pressure refrigerant liquid from said expander and evaporating said low pressure refrigerant liquid by absorbing heat from said source to be cooled to produce a relatively low pressure refrigerant vapor at a pressure of from about 40 to about 350 kPa, said refrigerant vapor exiting from said evaporator preferably having no substantial superheat; (f) at least one heat exchanger fluidly connected between said evaporator and said refrigerant suction of said compressor.

What is claimed is: 
     
         1 . A refrigeration system of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system having a capacity of from about 2 to about 30 tons and comprising:
 (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze);   (b) a centrifugal compressor having a refrigerant suction for receiving low-pressure refrigerant vapor at a pressure of from about 45 to about 75 kPa and discharge for discharging high pressure refrigerant vapor at a pressure of from about 100 to about 520 kPa, said compressor having an efficiency of at least about 0.65;   (c) a condenser fluidly connected to said refrigerant discharge of said compressor for receiving said high pressure refrigerant vapor and condensing at least a substantial portion of said refrigerant vapor by heat transfer with said heat sink to produce high pressure refrigerant liquid at temperature in the range of from about 10° C. to about 60° C.;   (d) an expander fluidly connected to said condenser for substantially isoenthalpically reducing the pressure of said high pressure refrigerant liquid to produce low pressure refrigerant liquid at a pressure of from about 45 to about 75 kPa;   (e) an evaporator fluidly connected to said expander for receiving said low pressure refrigerant liquid and evaporating said low pressure refrigerant liquid by absorbing heat from said source to be cooled to produce a low pressure refrigerant vapor at a pressure of from about 45 to about 75 kPa; and   (f) at least one heat exchanger fluidly connected between said evaporator and said refrigerant suction of said compressor, said at least one heat exchanger receiving at least a portion of said low pressure refrigerant vapor from said evaporator and heating said low pressure refrigerant vapor to produce a low pressure refrigerant vapor having a temperature at least about 5 C greater than the temperature of the vapor entering said at least one heat exchanger, said high temperature refrigerant vapor from said at least one heat exchanger fluidly connected to said compressor suction for providing low-pressure refrigerant vapor to said compressor.   
     
     
         2 . The refrigeration system of  claim 1  wherein said refrigerant comprises at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze) 
     
     
         3 . The refrigeration system of  claim 1  wherein said refrigerant comprises at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd). 
     
     
         4 . A refrigeration system of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system having a capacity of from about 2 to about 30 tons and comprising:
 (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least about 70% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze);   (b) a centrifugal compressor having a first stage and at least a second stage, each of said stages having a refrigerant suction for receiving a relatively low-pressure refrigerant vapor at pressure of from about 45 to about 75 kPa and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of from about 100 to about 520 kPa, said compressor having an efficiency of at least about 0.65;   (c) a condenser fluidly connected to said refrigerant discharge of said at least second stage of said compressor for receiving said high pressure refrigerant vapor from said at least a second stage and condensing at least a substantial portion of said refrigerant vapor by heat transfer with said heat sink to produce high pressure refrigerant liquid at temperature in the range of from about 10° C. to about 60° C.;   (d) at least a first expander fluidly connected to said condenser for substantially isoenthalpically reducing the pressure of at least a first portion of said high pressure refrigerant liquid to produce first low pressure refrigerant liquid at a pressure of from about 45 to about 75 kPa;   (e) at least a second expander fluidly connected to said condenser for substantially isoenthalpically reducing the pressure of at least a second portion of said high pressure refrigerant liquid to produce second low pressure refrigerant liquid at a pressure of from about 100 to about 520 kPa;   (f) an evaporator fluidly connected to said at least said first expander for receiving said first low pressure refrigerant liquid and evaporating said low pressure refrigerant liquid by absorbing heat from said source to be cooled to produce a low pressure refrigerant vapor at a pressure of from about 100 to about 520 kPa, at least a portion of said refrigerant vapor from said evaporator being fluidly connected to said first stage compressor suction; and   (g) at least one heat exchanger and/or at least one flash tank fluidly connected between said second expander and said suction of said at least second stage for receiving at least a portion of said second low pressure refrigerant liquid and discharging therefrom refrigerant vapor at about the pressure of said second low pressure refrigerant liquid, said refrigerant vapor at about the pressure of said second low pressure refrigerant liquid being fluidly connected to said second stage compressor suction.   
     
     
         5 . The refrigeration system of  claim 4  wherein said refrigerant comprises at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze). 
     
     
         6 . The refrigeration system of  claim 4  wherein said refrigerant comprises at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd). 
     
     
         7 . A refrigeration system of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system having a capacity of from about 2 to about 5 tons and comprising:
 (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze);   (b) a centrifugal compressor having a refrigerant suction for receiving a relatively low-pressure refrigerant vapor at pressure of from about 45 to about 75 kPa and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of from about 100 to about 520 kPa, said compressor having an efficiency of at least about 0.65;   (c) a condenser fluidly connected to said refrigerant discharge of said compressor for receiving said high pressure refrigerant vapor from said compressor and condensing at least a substantial portion of said refrigerant vapor by heat transfer with said heat sink to produce high pressure refrigerant liquid at temperature in the range of from about 45 to about 75 kPa;   (d) at least a first expander fluidly connected to said condenser for substantially isoenthalpically reducing the pressure of at least a first portion of said high pressure refrigerant liquid to produce first low pressure refrigerant liquid at a pressure of from about 45 to about 75 kPa; and   (e) an evaporator fluidly connected to said at least said first expander for receiving said low pressure refrigerant liquid and evaporating at least a portion of said low pressure refrigerant liquid by absorbing heat from said source to be cooled to produce a low pressure refrigerant vapor at a pressure of from about 45 to about 75 kPa, at least a portion of said refrigerant vapor from said evaporator being fluidly connected to said compressor suction, wherein at least one of said condenser and said evaporator is formed in substantial part of aluminum.   
     
     
         8 . The refrigeration system of  claim 7  wherein said refrigerant comprises at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze). 
     
     
         9 . The refrigeration system of  claim 7  wherein said refrigerant comprises at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd). 
     
     
         10 . A refrigeration system of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system having a capacity of from about 2 to about 30 tons and comprising:
 (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze);   (b) a centrifugal compressor having a refrigerant suction for receiving a relatively low-pressure refrigerant vapor at pressure of from about 45 to about 75 kPa and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of from about 100 kPa to about 520 kPa, said compressor having an efficiency of at least about 0.65;   (c) a condenser fluidly connected to said refrigerant discharge of said compressor for receiving said high pressure refrigerant vapor from said compressor and condensing at least a substantial portion of said refrigerant vapor by heat transfer with said heat sink to produce high pressure refrigerant liquid at temperature in the range of from about 10° C. to about 60° C.;   (d) at least a first expander fluidly connected to said condenser for substantially isoenthalpically reducing the pressure of at least a first portion of said high pressure refrigerant liquid to produce a low pressure stream comprising a combination of refrigerant liquid and refrigerant vapor at a pressure of from about 45 to about 75 kPa;   (e) a separator for receiving at least the combination of refrigerant vapor and refrigerant liquid from said at least first expander and producing at least one liquid effluent stream comprising liquid refrigerant at about said low pressure and no substantial vapor refrigerant and a low pressure vapor stream comprising refrigerant vapor at about said low pressure and no substantial liquid refrigerant;   and   (f) an evaporator fluidly connected to at least a portion of said at least one liquid effluent stream from said separator and evaporating at least a portion of said stream by absorbing heat from said source to be cooled to produce a low pressure refrigerant vapor at a pressure of from about 45 to about 75 kPa, at least a portion of said refrigerant vapor from said evaporator being fluidly connected to said compressor suction.   
     
     
         11 . The refrigeration system of  claim 10  wherein said refrigerant comprises at least about 80% by weight of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze). 
     
     
         12 . The refrigeration system of  claim 10  wherein said refrigerant comprises at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd). 
     
     
         13 . A refrigeration system of the type having a heat source to be cooled and a heat sink into which heat can be rejected, said system having a capacity of from about 2 to about 30 tons and comprising:
 (a) a heat transfer composition comprising a refrigerant having fire suppression features, preferably comprising at least about 95% by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least about 80% of trans1,3,3,3-tetrafluoropropene (transHFO-1234ze), in a closed loop refrigeration circuit;   (b) at least one sensor located in an area in the proximity of the heat source being cooled for sensing the existence of flame or fire in said proximity;   (c) a port in said closed loop refrigeration circuit in communication with relatively high pressure refrigerant vapor contained in said refrigeration system;   (d) a valve responsive to said sensor and fluidly connected to port for releasing at least a portion of said refrigerant vapor from said refrigeration system; and   (e) a conduit for transporting said refrigerant vapor to said proximity.