Refrigerant system with tandem compressors and reheat function

Abstract

A refrigerant system incorporates at least two compressors that act in tandem to provide variable control over the refrigerant system performance. The tandem compressors can be of conventional or economized type and are configured for maximum performance utilization. Further, a reheat circuit can be incorporated into the refrigerant system at several different locations. The reheat cycle provides additional control over sensible and latent capacity of the refrigerant system, and is particularly advantageous when utilized in combination with the tandem compressors. As a result, multiple steps of unloading can be implemented in all operation regimes, the external load demands are satisfied with much greater precision, eliminating undesirable variations in temperature and humidity, system efficiency and reliability are augmented and equipment life-cycle cost is reduced.

1 . A refrigerant system comprising: 
 an inlet manifold providing a supply of refrigerant to at least two compressors, and a discharge manifold receiving compressed refrigerant from said at least two compressors, said discharge manifold supplying refrigerant to a condenser;    refrigerant flowing to said condenser from said at least two compressors, and refrigerant flowing from said condenser to a main expansion device, refrigerant from said main expansion device flowing to an evaporator, and refrigerant from said evaporator returning to said inlet manifold;    an air moving device for moving air to an environment to be conditioned over said evaporator; and    a reheat coil communicating to a refrigerant line in said system, said reheat coil being positioned in a path of at least a portion of air having passed over said evaporator.    
     
     
         2 . The refrigerant system as set forth in  claim 1 , wherein said reheat coil communicating to the refrigerant line at a position between said discharge manifold and said condenser.  
     
     
         3 . The refrigerant system as set forth in  claim 2 , wherein an inlet to said reheat coil includes a selectively opened valve for controlling flow of refrigerant to said reheat coil.  
     
     
         4 . The refrigerant system as set forth in  claim 2 , wherein said reheat coil returns the refrigerant to a location upstream of said condenser.  
     
     
         5 . The refrigerant system as set forth in  claim 3 , wherein an outlet of said reheat coil is positioned downstream of said condenser and downstream of said valve, but upstream of said main expansion device.  
     
     
         6 . The refrigerant system as set forth in  claim 1 , wherein said refrigerant system further includes an economizer circuit, said economizer circuit receiving a tapped flow of refrigerant from a location downstream of said condenser, and passing said tapped flow of refrigerant through an economizer expansion device, said tapped flow of refrigerant and a main flow of refrigerant passing through an economizer heat exchanger.  
     
     
         7 . The refrigerant system as set forth in  claim 1 , wherein a bypass line selectively bypasses said condenser, and a control bypassing fluid around said condenser if humidification control is desired with less temperature control.  
     
     
         8 . The refrigerant system as set forth in  claim 6 , wherein said economizer circuit is upstream of said position at which said reheat coil communicates with said refrigerant line but downstream of said condenser.  
     
     
         9 . The refrigerant system as set forth in  claim 6 , wherein said economizer circuit is downstream of said position at which said reheat coil communicates with said refrigerant line.  
     
     
         10 . The refrigerant system as set forth in  claim 6 , wherein said economizer circuit is in parallel arrangement with said reheat coil.  
     
     
         12 . The refrigerant system as set forth in  claim 6 , wherein at least one said compressor has an intermediate injection port.  
     
     
         13 . The refrigerant system as set forth in  claim 1 , wherein an unloader allows selective unloading of at least one of said at least two compressors.  
     
     
         14 . A method of operating a refrigerant system comprising the steps of: 
 (1) providing an inlet manifold to supply refrigerant to at least two compressors and a discharge manifold receiving compressed refrigerant from said at least two compressors, said discharge manifold supplying refrigerant to a condenser, providing an expansion device downstream of the condenser, an evaporator downstream of the expansion device, and a reheat coil for selectively receiving refrigerant, and an air moving device for passing air into an environment to be conditioned, and over said evaporator and said reheat coil; and    (2) selectively operating one or both of said at least two compressors to achieve a desired cooling capacity, and selectively communicating refrigerant into said reheat coil to provide a desired temperature to said air passing into said environment to be conditioned.    
     
     
         15 . The method as set forth in  claim 14 , wherein said reheat coil is communicated into a refrigerant line at a position between said discharge manifold and said condenser.  
     
     
         16 . The method as set forth in  claim 15 , wherein said reheat coil returns refrigerant to a location upstream of said condenser.  
     
     
         17 . The method as set forth in  claim 14 , wherein an outlet of said reheat coil is positioned downstream of said condenser, but upstream of said main expansion device.  
     
     
         18 . The method as set forth in  claim 14 , further providing an economizer circuit, said economizer circuit receiving a tapped flow of refrigerant from a location downstream of said condenser, and including the steps of selectively passing said tapped flow of refrigerant through an economizer expansion device, and passing a main flow of refrigerant through an economizer heat exchanger along with selectively passing said tapped flow of refrigerant through said economizer heat exchanger.  
     
     
         19 . The method as set forth in  claim 18 , wherein said tapped flow of refrigerant is returned to at least one of said at least two compressors at an intermediate compression point.  
     
     
         20 . The method as set forth in  claim 18 , wherein said economizer circuit is positioned to be upstream of a position at which said reheat coil communicates with said refrigerant line, and downstream of said condenser.  
     
     
         21 . The method as set forth in  claim 18 , wherein said economizer circuit is positioned to be downstream of said position at which said reheat coil communicates with said refrigerant line.  
     
     
         22 . The method as set forth in  claim 18 , wherein said economizer circuit is positioned to be in a parallel arrangement with said reheat coil.  
     
     
         23 . The method as set forth in  claim 14 , wherein at least one of said at least two compressors is provided with an unloader, and said unloader is controlled to provide variable system performance.