Integrated dehumidification system

Abstract

A dynamic system controls indoor relative humidity and temperature to achieve specified conditions by applying multiple stages of dehumidification. In addition to an optional stage that increases dehumidification by reducing the speed of the indoor blower, the system uses a reheat coil and multiple valves that allow the reheat coil to function as either a subcooling coil or a partial condenser. Thus the system can maintain specified indoor temperature and humidity conditions even at times when no heating or cooling is needed. The system may have an outdoor condensing unit including a compressor and a condenser operably connected via refrigerant lines to an indoor unit to form a “split system” refrigerant loop.

1 . A system for controlling indoor environmental conditions, comprising: 
 a vapor-compression refrigerant loop with a compressor, a condenser, a reheat coil, an expansion device, and an evaporator coil;    an air mover that drives an indoor air stream sequentially across the evaporator and a reheat coil;    a plurality of valves disposed within the vapor-compression loop; and    a controller operably connected to the vapor-compression loop, the air mover and the plurality of valves, wherein the condenser discharges heat to an outdoor environment, and the controller controls a plurality of dehumidification stages including a stage that causes refrigerant to condense in the reheat coil.    
   
   
       2 . The system of  claim 1 , wherein the refrigerant loop includes a receiver for refrigerant volume control.  
   
   
       3 . The system of  claim 1 , wherein one of the plurality of dehumidification stages minimizes dehumidification of indoor air by operating the air mover at a normal speed and directing a refrigerant in the refrigerant loop to bypass the reheat coil by operating at least one of the plurality of valves.  
   
   
       4 . The system of  claim 1 , wherein one of the plurality of dehumidification stages increases dehumidification of indoor air by reducing a speed of the air mover to reduce a velocity of the indoor air stream across the evaporator and the reheat coil.  
   
   
       5 . The system of  claim 1 , wherein at least one of the plurality of dehumidification stages protects the condenser from low refrigerant pressures by reducing a rate at which the condenser discharges heat to the outdoor environment.  
   
   
       6 . The system of  claim 1 , wherein the condenser is cooled by a second air stream driven by at least one condenser fan and a flow rate of the second air stream is controlled by controlling the at least one condenser fan.  
   
   
       7 . The system of  claim 6 , wherein the at least one condenser fan operates at a single speed and is cycled on and off to reduce a heat exchange rate of the second air stream.  
   
   
       8 . The system of  claim 1 , wherein the controller is operably connected to an indoor temperature sensor, an indoor humidity sensor, at least one of the plurality of valves, and the controller includes control logic that controls the air mover, the condenser, and the at least one of the plurality of valves based on input from at least one of the indoor temperature sensor and the indoor humidity sensor.  
   
   
       9 . The system of  claim 2 , wherein the refrigerant receiver is located between the condenser and the evaporator.  
   
   
       10 . The system of  claim 2 , wherein the reheat coil is located in a first parallel path between the condenser and the expansion device, and the receiver is located in a second parallel path between the condenser and the expansion device.  
   
   
       11 . The system of  claim 10 , wherein a first bypass path is provided between an outlet of the reheat coil and an inlet of the receiver.  
   
   
       12 . The system of  claim 11 , wherein a second bypass path is provided between an inlet of the reheat coil and an outlet of the receiver.  
   
   
       13 . The system of  claim 12 , wherein the plurality of valves includes first and second refrigerant valves placed in the second parallel path between the condenser and the expansion device and wherein the first refrigerant valve is placed between the condenser and the receiver, and the second refrigerant valve is placed between the receiver and the expansion device.  
   
   
       14 . The system of  claim 13 , wherein the first bypass path joins the second parallel path between the condenser and the expansion device at a location between the first refrigerant valve and the receiver, and the plurality of valves includes a check valve located in the first bypass path to prevent refrigerant flow from the inlet of the receiver to the outlet of the reheat coil.  
   
   
       15 . The system of  claim 14 , wherein the plurality of valves includes first and second pressure-reducing check valves located in the first parallel path between the condenser and the expansion device, and wherein the first pressure-reducing check valve is located between the condenser and the reheat coil, and the second pressure-reducing check valve is located between the reheat coil and the expansion device.  
   
   
       16 . The system of  claim 15 , wherein the second bypass path joins the first parallel path between the first pressure-reducing check valve and the reheat coil, and the first bypass path joins the first parallel path between the reheat coil and the second pressure-reducing check valve.  
   
   
       17 . A system for controlling indoor environmental conditions, comprising: 
 an outdoor condensing unit including a compressor and a condenser operably connected via refrigerant lines;    an indoor unit operably connected to the outdoor condensing unit to form a refrigerant loop, the indoor unit comprising: 
 an evaporator coil, a reheat coil, an expansion device, a refrigerant receiver for refrigerant volume control, an expansion device, and a plurality of valves, operably connected via refrigerant lines;  
 an air mover that drives a first air stream sequentially across the evaporator coil and the reheat coil; and  
 a controller operably connected to the outdoor condensing unit and the indoor condensing unit, wherein the condenser discharges heat to outdoor air, the reheat coil is located downstream of the evaporator coil in the first air stream, and the controller controls a plurality of dehumidification stages.  
   
   
   
       18 . The system of  claim 17 , wherein the plurality of dehumidification stages includes a stage that causes refrigerant in the refrigerant loop to condense in the reheat coil.