Vapor compression system and method

Abstract

A vapor compression refrigeration system includes an evaporator, a compressor, and a condenser interconnected in a closed-loop system. In one embodiment, a multifunctional valve is configured to receive a liquified heat transfer fluid from the condenser and a hot vapor from the compressor. A saturated vapor line connects the outlet of the multifunctional valve to the inlet of the evaporator and is sized so as to substantially convert the heat transfer fluid exiting the multifunctional valve into a saturated vapor prior to delivery to the evaporator. The multifunctional valve regulates the flow of heat transfer fluid through the valve by monitoring the temperature of the heat transfer fluid returning to the compressor through a suction line coupling the outlet of the evaporator to the inlet of the compressor. Separate gated passageways within the multifunctional valve permit the refrigeration system to be operated in defrost mode by flowing hot vapor through the saturated vapor line and the evaporator in a forward-flow process thereby reducing the amount of time necessary to defrost the system and improving the overall system performance.

1 . A vapor compression system comprising: 
 a compressor for increasing the pressure and temperature of a heat transfer fluid;    a condenser for liquefying the heat transfer fluid;    an evaporator for transferring heat from ambient surroundings to the heat transfer fluid;    a multifunctional valve having a first inlet and a second inlet and an outlet;    a saturated vapor line connecting the outlet of the multifunctional valve to the inlet of the evaporator;    a liquid line connecting the condenser to the first inlet of the multifunctional valve;    a discharge line connecting the compressor to the second inlet of the multifunctional valve;    a suction line connecting the evaporator to the compressor; and    a temperature sensor mounted to the suction line and operatively connected to the multifunctional valve,    wherein the saturated vapor line is of sufficient length to vaporize a substantial portion of the heat transfer fluid before the heat transfer fluid enters the evaporator.    
     
     
         2 . The vapor compression system of  claim 1 , wherein the multifunctional valve comprises: 
 a first passageway coupled to the first inlet, the first passageway gated by a first solenoid valve;    a second passageway coupled to the second inlet, the second passageway gated by a second solenoid valve; and    a mechanical metering valve positioned in the first passageway and activated by the temperature sensor.    
     
     
         3 . The vapor compression system of  claim 1 , further comprising a unit enclosure and a refrigeration case, wherein the compressor, evaporator, multifunctional valve, and temperature sensor are located within the unit enclosure, and wherein the evaporator is located within the refrigeration case.  
     
     
         4 . The vapor compression system of  claim 1 , wherein the compressor comprises a plurality of compressors each coupled to the suction line by an input manifold and each discharging into a collector manifold connected to the discharge line.  
     
     
         5 . The vapor compression system of  claim 1  further comprising: 
 a plurality of evaporators;  
 a plurality of multifunctional valves;  
 a plurality of saturated vapor lines, wherein each saturated vapor line connects one of the plurality of multifunctional valves to one of the plurality of evaporators;  
 a plurality of suction lines, wherein each suction line connects one of the plurality of evaporators to the compressor,  
 wherein each of the plurality of suction lines has a temperature sensor mounted thereto for relaying a signal to a selected one of the plurality of multifunctional valves.  
 
     
     
         6 . A vapor compression system comprising: 
 an evaporator;    a compressor configured to receive a heat transfer fluid from the evaporator and to discharge the a heat transfer fluid at relatively high temperature and pressure;    a condenser configured to receive the heat transfer fluid from the compressor at an inlet and to discharge the heat transfer fluid in a liquid state;    a multifunctional valve configured to receive the heat transfer fluid in the liquid state at a first inlet and in the vapor state at a second inlet,    wherein the multifunctional valve includes a first passageway coupled to the first inlet, the first passageway having a metering valve positioned therein and gated by a first valve, and a second passageway coupled to the second inlet and gated by a second valve, and a common chamber, and    wherein the first and second passageways terminate at the common chamber;    a liquid line connected to the condenser and to the first inlet of the multifunctional valve; and    a bifurcated discharge line connected to the compressor and having a first portion connected to the condenser and a second portion connected to the second inlet of the multifunctional valve.    
     
     
         7 . The vapor compression system of  claim 6 , wherein the first and second valves comprise solenoid valves.  
     
     
         8 . The vapor compression system of  claim 6  further comprising a suction line connecting the evaporator to the compressor and a pressure regulating valve positioned in the suction line, and wherein the first valve in the multifunctional valve comprises a check valve.  
     
     
         9 . The vapor compression system of  claim 6  further comprising a suction line connecting the evaporator to the compressor and a temperature sensor mounted to the suction line and operably connected to the multifunctional valve.  
     
     
         10 . The vapor compression system of  claim 6  further comprising: 
 a plurality of evaporators;  
 a plurality of multifunctional valves;  
 a plurality of saturated vapor lines, wherein each saturated vapor line connects one of the plurality of multifunctional valves to one of the plurality of evaporators; and  
 a plurality of suction lines, wherein each suction line connects one of the plurality of evaporators to the compressor,  
 wherein each of the plurality of suction lines has a temperature sensor mounted thereto for relaying a signal to a selected one of the plurality of multifunctional valves.  
 
     
     
         11 . A method for operating a vapor compression system comprising: 
 providing a multifunctional valve including a first inlet for receiving a heat transfer fluid in the liquid state, a second inlet for receiving the heat transfer fluid in the gaseous state, a first passageway coupling the first inlet to a common chamber, the first passageway having a metering valve positioned therein and gated by a first valve, and a second passageway coupling the second inlet to the common chamber, the second passageway gated by a second valve;    compressing the heat transfer fluid to a relatively high temperature and pressure and flowing the heat transfer fluid through a first discharge line to a condenser and through a second discharge line to the second inlet of the multifunctional valve through the first pathway in the multifunctional valve;    flowing the heat transfer fluid from the condenser through a liquid line to the first inlet of the multifunctional valve,    wherein the heat transfer fluid undergoes volumetric expansion at the metering valve;    collecting the heat transfer fluid in the common chamber and flowing the heat transfer fluid through a saturated vapor line to an evaporator,    wherein the flow rate of the heat transfer fluid in the saturated vapor line and the length of the saturated vapor line between the multifunctional valve and the evaporator is sufficient to vaporize a substantial portion of the heat transfer fluid to form a saturated vapor before the heat transfer fluid enters the evaporator,    wherein the saturated vapor substantially fills the evaporator, and    wherein heat is transferred to the saturated vapor from the ambient surroundings; and    returning the saturated vapor to the compressor through a suction line.    
     
     
         12 . The method of  claim 11 , wherein a process for defrosting the evaporator comprises closing the first valve and opening the second valve in the multifunctional valve to stop the flow of heat transfer fluid in the first passageway and to initiate the flow of the heat transfer fluid from the compressor to the common chamber through the second passageway.  
     
     
         13 . The method of  claim 11 , wherein flowing the heat transfer to the saturated vapor line comprises: 
 measuring the temperature of the heat transfer fluid in the suction line at a point in close proximity to the compressor; and    relaying a signal to the multifunctional valve to actuate the metering valve.    
     
     
         14 . The method of  claim 11 , further comprising flowing about 3 to about 5 lbs/min (1.36 to 2.27 kg/min) of heat transfer fluid, wherein the heat transfer fluid comprises a fluid selected from the group consisting of R-12 and R-22.  
     
     
         15 . The method of  claim 14 , wherein the evaporator is sized to handle about a cooling load of about 12000 Btu/hr (84 g cal/s).  
     
     
         16 . The method of  claim 14 , wherein the heat transfer fluid flows through the saturated vapor line at a rate of about 2500 (76 m/min) to about 3700 ft/min (1128 m/min).  
     
     
         17 . A vapor compression system for transferring heat from an ambient atmosphere by flowing a heat transfer fluid comprising: 
 a compressor;    a condenser;    a discharge line coupling the compressor to the condenser;    an evaporator;    a suction line coupling the evaporator to the condenser;    an expansion valve;    a liquid line coupling the condenser to the expansion valve; and    a saturated vapor line coupling the expansion valve to the evaporator, wherein the saturated vapor line is characterized by a diameter and by a length, and wherein the diameter and the length is sufficient to substantially convert the heat transfer fluid into a saturated vapor prior to delivery to the evaporator.    
     
     
         18 . The vapor compression system of  claim 17 , wherein the expansion valve comprises a multifunctional valve having a first expansion chamber and a second expansion chamber and a passageway coupling the first expansion chamber to the second expansion chamber, such that liquefied heat transfer fluid undergoes a first volumetric expansion in the first expansion chamber and a second volumetric expansion in the second expansion chamber.  
     
     
         19 . The vapor compression system of  claim 18 , wherein the diameter and the length of the saturated vapor line are sufficient to substantially convert about 3 to 5 lbs/min (1.36 to 2.27 kg/min) of R-12 to a saturated vapor.  
     
     
         20 . The vapor compression system of  claim 18 , wherein the multifunctional valve further comprises a second passageway coupling the discharge line from the compressor to the saturated vapor line, and a gate valve positioned in the second passageway such that hot vapor from the compressor can flow to the saturated vapor line when the gate valve is opened.