Method and system for dehumidification and refrigerant pressure control

Abstract

A method for dehumidification and controlling system pressure in a refrigeration system includes providing a refrigeration system having a compressor, a condenser and an evaporator connected in a closed refrigerant loop. Each of the condenser and evaporator have a plurality of refrigerant circuits. A first heat transfer fluid is flowed over the condenser and a second heat transfer fluid is flowed over the evaporator. At least one of the refrigerant circuits of the condenser is isolated to provide a decreased amount of heat transfer area within the condenser and to increase the refrigerant pressure within the refrigeration system when the refrigerant pressure within the refrigeration system is at or below a predetermined pressure. At least one of the refrigerant circuits of the evaporator is isolated to dehumidify and maintain the temperature of the second heat transfer fluid at or above a predetermined temperature when dehumidification is required.

1 . A method for dehumidification and controlling system pressure in a refrigeration system comprising the steps of: 
 providing a refrigeration system having a compressor, a condenser and an evaporator connected in a closed refrigerant loop, each of the condenser and evaporator having a plurality of refrigerant circuits;    flowing a first heat transfer fluid over the condenser;    flowing a second heat transfer fluid over the evaporator;    controlling a flow of refrigerant in the plurality of refrigerant circuits in the condenser to control an amount of heat transfer between refrigerant in the condenser and the first heat transfer fluid;    controlling a flow of refrigerant in the plurality of refrigerant circuits in the evaporator to control an amount of heat transfer between refrigerant in the evaporator and the second heat transfer fluid;    isolating at least one of the refrigerant circuits of the condenser to provide a decreased amount of heat transfer area within the condenser and to increase refrigerant pressure within the refrigeration system when the refrigerant pressure within the refrigeration system is at or below a predetermined pressure; and    configuring the plurality of refrigerant circuits of the evaporator to provide dehumidification of the second heat transfer fluid without overcooling the second heat transfer fluid.    
   
   
       2 . The method of  claim 1 , further comprising drawing refrigerant from the at least one of the circuits isolated from refrigerant flow in the condenser by fluidly connecting the isolated portion of the condenser to the suction of the compressor.  
   
   
       3 . The method of  claim 2 , wherein refrigerant from the isolated portion of the condenser is drawn into the refrigeration system to increase the refrigerant pressure.  
   
   
       4 . The method of  claim 1 , further comprising measuring refrigerant pressure at a predetermined location in the refrigeration system.  
   
   
       5 . The method of  claim 1 , the method further comprising: 
 providing a first control valve fluidly connected to a first set of circuits of the plurality of circuits of the evaporator, wherein the first control valve controls flow of refrigerant to the first set of circuits of the evaporator; and    providing a second control valve fluidly connected to a second set of circuits of the plurality of circuits of the evaporator, wherein the second refrigerant control valve controls flow of refrigerant to the second set of circuits of the evaporator.    
   
   
       6 . The method of  claim 5 , wherein the second control valve permits a greater amount of refrigerant flow than the first control valve.  
   
   
       7 . The method of  claim 6 , wherein the first and second control valves are thermostatic expansion valves.  
   
   
       8 . The method of  claim 5 , the method further comprising: 
 isolating the first set of circuits of the evaporator from flow of refrigerant from the condenser; and    providing at least a portion of refrigerant discharged from the compressor to the first set of circuits of the evaporator without flowing through the condenser.    
   
   
       9 . The method of  claim 8 , wherein the step of providing at least a portion of refrigerant includes flowing refrigerant from the compressor through a fluid connection to an inlet of the first set of circuits of the evaporator.  
   
   
       10 . The method of  claim 9 , wherein the step of providing at least a portion of refrigerant includes: 
 connecting a discharge of the compressor to an outlet of the first set of circuits of the evaporator,    flowing refrigerant from the compressor through a fluid connection to the first set of circuits, the flow of refrigerant from the compressor through the first set of circuits of the evaporator being countercurrent to a flow of refrigerant in the second set of circuits of the evaporator, and    combining the flow of refrigerant through the first set of circuits with the inlet flow of refrigerant of the second set of circuits of the evaporator.    
   
   
       11 . The method of  claim 10 , further comprising condensing the refrigerant flowing in the first set of circuits countercurrent to the flow of refrigerant in the second set of circuits from a gas to a liquid, wherein the liquid flows into the second set of circuits of the evaporator.  
   
   
       12 . A method for dehumidification and controlling refrigerant pressure in a heating, ventilation and air conditioning system comprising: 
 providing a closed loop refrigerant system comprising a compressor, a condenser and an evaporator, each of the condenser and evaporator having a plurality of refrigerant circuits configured and disposed to allow isolation of at least one of the refrigerant circuits from refrigerant flow;    measuring refrigerant pressure at a predetermined location in the refrigeration system;    determining an operational mode for the refrigeration cycle, the operational mode being a selected from the group consisting of cooling and dehumidification;    isolating at least one of the refrigeration circuits in the condenser from refrigerant flow when the measured pressure at the predetermined location is equal to or less than a predetermined pressure;    isolating a first set of refrigerant circuits in the evaporator from flow of refrigerant from the condenser when the operational mode is dehumidification;    permitting flow of refrigerant from the condenser to both the first set of circuits and a second set of refrigerant circuits in the evaporator when the operational mode is cooling; and    wherein the refrigerant pressure is increased by isolation of at least one of the refrigerant circuits in the condenser from refrigerant flow until the measured pressure is greater than the predetermined pressure.    
   
   
       13 . The method of  claim 12 , further comprising dehumidifying a heat transfer fluid flowing over both the first and second set of circuits when the operational mode is dehumidification.  
   
   
       14 . The method of  claim 12 , wherein the predetermined location is the outlet of the evaporator.  
   
   
       15 . The method of  claim 14 , wherein the predetermined pressure is a pressure corresponding to an icing condition of the evaporator.  
   
   
       16 . The method of  claim 12 , further comprising drawing refrigerant from the at least one circuit isolated from refrigerant flow in the condenser by fluidly connecting a portion of the condenser including the at least one circuit isolated from refrigerant flow to the suction of the compressor.  
   
   
       17 . The method of  claim 16 , wherein refrigerant from the portion of the condenser including the at least one circuit isolated from refrigerant flow is added to the refrigeration system to increase the refrigerant pressure.  
   
   
       18 . The method of  claim 12 , further comprising: 
 providing a first control valve fluidly connected to the first set of circuits of the plurality of circuits of the evaporator, wherein the first control valve controls flow of refrigerant to the first set of circuits of the evaporator; and    providing a second control valve fluidly connected to the second set of circuits of the plurality of circuits of the evaporator, wherein the second refrigerant control valve controls flow of refrigerant to the second set of circuits of the evaporator.    
   
   
       19 . The method of  claim 18 , wherein the second control valve permits a greater amount of refrigerant flow than the first control valve.  
   
   
       20 . The method of  claim 19 , wherein the first and second control valves are thermostatic expansion valves.  
   
   
       21 . The method of  claim 18 , further comprising: 
 providing at least a portion of refrigerant discharged from the compressor to the first set of circuits of the evaporator without first flowing through the condenser.    
   
   
       22 . The method of  claim 21 , wherein the providing at least a portion of refrigerant step includes flowing refrigerant from the compressor through a fluid connection to an inlet of the first set of circuits of the evaporator.  
   
   
       23 . The method of  claim 21 , wherein the providing at least a portion of refrigerant step includes: 
 connecting a discharge of the compressor to an outlet of the first set of circuits of the evaporator;    flowing refrigerant from the compressor through a fluid connection to the first set of circuits, the flow of refrigerant from the compressor through the first set of circuits of the evaporator being countercurrent to the flow of refrigerant in the second set of circuits of the evaporator; and    combining the flow of refrigerant through the first set of circuits with an inlet flow of refrigerant to the second set of circuits of the evaporator.    
   
   
       24 . The method of  claim 23 , further comprising condensing the refrigerant flowing in the first set of circuits countercurrent to the flow of refrigerant in the second set of circuits from a gas to a liquid, wherein the liquid is flowed into the second set of circuits of the evaporator.  
   
   
       25 . A heating, ventilation and air conditioning system comprising: 
 a compressor;    a condenser arrangement comprising: 
 a plurality of circuits arranged into a first and second portion; and  
 a valve arrangement configured and disposed to isolate the first portion of the condenser arrangement when the refrigerant pressure is below a predetermined pressure; and  
   an evaporator arrangement comprising: 
 a plurality of circuits arranged into a first and second portion;  
 at least one distributor configured to distribute and deliver refrigerant to each circuit of the plurality of circuits in the evaporator; and  
 a valve arrangement configured and disposed to isolate the first portion of the evaporator arrangement from refrigerant flow in a dehumidification operation.  
   
   
   
       26 . The system of  claim 25 , further comprising: 
 a first control valve fluidly connected to the first portion of the evaporator, wherein the first control valve controls flow of refrigerant to the first portion of the evaporator arrangement; and    a second control valve fluidly connected to the second portion of the evaporator arrangement, wherein the second control valve controls flow of refrigerant to the second portion of the evaporator arrangement.    
   
   
       27 . The system of  claim 26 , wherein the second control valve permits a greater amount of refrigerant flow than the first control valve.  
   
   
       28 . The system of  claim 27 , wherein the first and second control valves are thermostatic expansion valves.  
   
   
       29 . The system of  claim 25 , further comprising a fluid connection to connect the compressor to the first portion of the evaporator arrangement, the fluid connection being configured to allow flow of at least a portion of refrigerant discharged from the compressor to the first portion of the evaporator arrangement without traveling through the condenser arrangement during a dehumidification operation.  
   
   
       30 . The system of  claim 29 , wherein the fluid connection connects a discharge of the compressor to an inlet of the first portion of the evaporator arrangement.  
   
   
       31 . The system of  claim 29 , wherein the fluid connection connects a discharge of the compressor to an outlet of the first portion of the evaporator arrangement, wherein flow of refrigerant from the compressor through the first portion of the evaporator arrangement is permitted to flow countercurrent to the flow of refrigerant in the second portion of the evaporator arrangement, refrigerant flowing in the first portion of the evaporator arrangement combines with refrigerant at an inlet of the second portion of the evaporator arrangement.  
   
   
       32 . The system of  claim 31 , wherein the refrigerant flowing countercurrent to the flow of refrigerant in the second portion of the evaporator arrangement condenses from a gas to a liquid and the liquid flows into the second portion of the evaporator arrangement.