Start-up procedure for refrigerant systems having microchemical consensor and reheat cycle

Abstract

A refrigerant system has a condenser of microchannel design and construction and includes a reheat cycle. The reheat cycle includes a refrigerant flow control device, such as a three-way valve, for selectively routing at least a portion of refrigerant through a reheat heat exchanger from a location between a compressor and expansion device. A control for the refrigerant system selectively actuates this refrigerant flow control device to route at least a portion of refrigerant through the reheat heat exchanger at system start-up.

1 . A refrigerant system comprising:
 a compressor for delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor; and   said condenser being a microchannel heat exchanger;   a reheat cycle including a refrigerant flow control device for selectively routing at least a portion of refrigerant through a reheat heat exchanger, said refrigerant flow control device being positioned to route said at least portion of refrigerant through said reheat heat exchanger from a location between said compressor and said expansion device, and said reheat heat exchanger being positioned in a path of air that has passed over said evaporator; and   a control for the system selectively actuating said switch to route at least a portion of refrigerant through said reheat heat exchanger at refrigerant system start-up.   
     
     
         2 . The refrigerant system as set forth in  claim 1 , wherein said control is also routing said at least a portion of refrigerant through said reheat heat exchanger when at least one of a start-up, compressor speed change, tandem compressor activation or high ambient temperature conditions occur. 
     
     
         3 . The refrigerant system as set forth in  claim 2 , wherein said conditions are programmed in the control to identify when to selectively actuate said refrigerant flow control device to route refrigerant through said reheat heat exchanger. 
     
     
         4 . The refrigerant system as set forth in  claim 1 , wherein a bypass is provided around said condenser to selectively bypass at least a portion of refrigerant around said condenser. 
     
     
         5 . The refrigerant system as set forth in  claim 1 , wherein said refrigerant flow control device routes said at least portion of refrigerant from a location between said compressor and said expansion device, and downstream of said compressor. 
     
     
         6 . The refrigerant system as set forth in  claim 1 , wherein said refrigerant flow control device is actuated to selectively allow for refrigerant flow through the reheat heat exchanger for at least a predetermined period of time after said condition is identified. 
     
     
         7 . The refrigerant system as set forth in  claim 6 , wherein said predetermined period of time is preferably from 15 seconds to 3 minutes. 
     
     
         8 . The refrigerant system as set forth in  claim 1 , wherein said refrigerant flow control device is one of adjustable type through modulation or pulsation or of an on/off type. 
     
     
         9 . The refrigerant system as set forth in  claim 1 , wherein said microchannel heat exchanger includes a plurality of heat exchange tube each having a plurality of parallel refrigerant channels. 
     
     
         10 . The refrigerant system as set forth in  claim 9 , wherein said microchannel heat exchanger having flow channels with a hydraulic diameter less than or equal to 5 mm. 
     
     
         11 . The refrigerant system as set forth in  claim 1 , wherein all of the refrigerant passes through said reheat heat exchanger. 
     
     
         12 . A method of operating a refrigerant system comprising the steps of:
 a) delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor;   b) said condenser being a microchannel heat exchanger;   c) selectively routing at least a portion of refrigerant through a reheat heat exchanger from a location between said compressor and said expansion device, and passing at least a portion of air over said reheat heat exchanger after the air has passed over said evaporator; and   d) selectively actuating a refrigerant flow control device to route said at least portion of refrigerant through said reheat heat exchanger at system start-up.   
     
     
         13 . The method as set forth in  claim 12 , further comprising the step of routing said at least a portion of refrigerant through said reheat heat exchanger when at least one of a start-up, compressor speed change, tandem compressor activation or high ambient temperature occurs. 
     
     
         14 . The method as set forth in  claim 12 , further comprising the step of selectively allowing refrigerant flow through the reheat heat exchanger for at least a predetermined period of time after refrigerant system start-up. 
     
     
         15 . The method as set forth in  claim 12 , wherein all of the refrigerant passes through said reheat heat exchanger.