System Reheat Control by Pulse Width Modulation

Abstract

A refrigerant system is provided with a reheat circuit. A pulse width modulation control is provided to achieve variable reheat capacity and thus to satisfy a wide spectrum of temperature and humidity levels in an environment conditioned by a refrigerant system. The pulse width modulation signal provided for the reheat flow control device achieves incremental amounts of reheat while avoiding temperature and humidity variations in the conditioned space.

1 . A refrigerant system comprising:
 a compressor, a condenser downstream of said compressor, an expansion device downstream of said condenser and an evaporator downstream of said expansion device,   a reheat circuit for selectively receiving refrigerant through a reheat heat exchanger, an air-moving device passing air over said evaporator and said reheat heat exchanger; and   a control for selectively operating a valving system to deliver refrigerant through said reheat heat exchanger, and said control being operable to utilize pulse width modulation signal to operate the valving system to achieve levels of temperature and humidity control between the levels of control with said reheat circuit being continuously operational, and the levels of control without said reheat circuit being operational.   
   
   
       2 . The refrigerant system as set forth in  claim 1 , wherein said reheat circuit receives refrigerant in a serial flow arrangement relative to said condenser. 
   
   
       3 . The refrigerant system as set forth in  claim 2 , wherein said reheat circuit receives refrigerant from a location upstream of said condenser. 
   
   
       4 . The refrigerant system as set forth in  claim 2 , wherein said reheat circuit receives refrigerant from a location downstream of said condenser. 
   
   
       5 . The refrigerant system as set forth in  claim 1 , wherein a bypass is provided for selectively bypassing at least a portion of refrigerant around said condenser. 
   
   
       6 . The refrigerant system as set forth in  claim 5 , wherein said bypass is controlled by a pulse width modulation valve. 
   
   
       7 . The refrigerant system as set forth in  claim 1 , wherein said reheat circuit is controlled by a three-way valve. 
   
   
       8 . The refrigerant system as set forth in  claim 1 , wherein said valving system consists of at least one valve. 
   
   
       9 . The refrigerant system as set forth in  claim 8 , wherein said at least one valve is a three-way valve. 
   
   
       10 . A method of controlling a refrigerant system comprising the steps of:
 (1) providing a compressor, a condenser downstream of said compressor, an expansion device downstream of said condenser, an evaporator downstream of said expansion device, a reheat circuit to selectively receive a refrigerant through a reheat heat exchanger, and an air-moving device to move air over said evaporator and said reheat heat exchanger; and   (2) operating said refrigerant system by selectively actuating said reheat circuit to pass refrigerant through said reheat heat exchanger, and operating a control to utilize pulse width modulation signal to operate a valving system to direct refrigerant to said reheat circuit to provide levels of temperature and humidity control intermediate discrete levels provided by actuating or not actuating said reheat circuit.   
   
   
       11 . The method as set forth in  claim 10 , further including the steps of selectively bypassing said condenser by routing at least a portion of refrigerant around said condenser. 
   
   
       12 . The method as set forth in  claim 11 , wherein said bypass is controlled by a pulse width modulation valve. 
   
   
       13 . The method as set forth in  claim 10 , wherein said reheat circuit receives refrigerant in a serial fashion relative to said condenser. 
   
   
       14 . The method as set forth in  claim 13 , wherein said reheat circuit receives refrigerant from a location upstream of said condenser. 
   
   
       15 . The method as set forth in clam  13 , wherein said reheat circuit receives refrigerant from a location downstream of said condenser. 
   
   
       16 . The method as set forth in  claim 10 , wherein said valving system consists of at least one valve. 
   
   
       17 . The method as set forth in  claim 16 , wherein said at least one valve is a three-way valve.