Control Device for HVAC Systems with Inlet and Outlet Flow Control Devices

Abstract

A process for controlling operation of a heating, ventilation and air conditioning system broadly comprises providing a heating, ventilation and air conditioning system having an evaporator, a condenser, a compressor having an inlet and an outlet, and at least one flow control device; measuring a performance parameter of the heating, ventilation and air conditioning system; determining a performance parameter measurement of the flow indicative of onset of surge; determining a surge line of the heating, ventilation and air conditioning system based upon the performance parameter measurement; and independently controlling the at least one flow control device based upon the performance parameter to mitigate an onset of the surge.

1 . A process for controlling operation of a heating, ventilation and air conditioning system, comprising:
 providing a heating, ventilation and air conditioning system having an evaporator, a condenser, a compressor having an inlet and an outlet, and at least one flow control device in communication with the inlet or the outlet or both the inlet and the outlet;   measuring a performance parameter of the heating, ventilation and air conditioning system;   determining a performance parameter measurement indicative of onset of surge;   determining a surge line of the heating, ventilation and air conditioning system based upon the performance parameter measurement; and   independently controlling the at least one flow control device based upon the performance parameter to mitigate an onset of the surge.   
     
     
         2 . The process of  claim 1 , wherein measuring the performance parameter comprises the steps of:
 measuring a first pressure of the heating, ventilation and air conditioning system at a location upstream from the compressor;   measuring a second pressure of the heating, ventilation and air conditioning system at a location downstream from the compressor; and   determining a pressure ratio.   
     
     
         3 . The process of  claim 1 , wherein measuring the performance parameter comprises the steps of:
 calculating a first saturation temperature at a location upstream from the compressor;   calculating a second saturation temperature at a location downstream from the compressor; and   determining a saturation temperature difference.   
     
     
         4 . The process of  claim 1 , wherein measuring the performance parameter comprises calculating a head of the compressor. 
     
     
         5 . The process of  claim 1 , wherein measuring the performance parameter comprises the steps of:
 calculating a first saturation pressure at a location upstream of the compressor;   calculating a second saturation pressure at a location downstream of the compressor; and   determining a saturation pressure difference.   
     
     
         6 . The process of  claim 1 , wherein independently controlling the heating, ventilation and air conditioning system comprises controlling the operation of any one of the following: a compressor or at least one flow control device or both the compressor and at least one flow control device. 
     
     
         7 . The process of  claim 6 , wherein the at least one flow control device comprises at least one inlet flow control device or at least one outlet flow control device or both at least one inlet flow control device and at least one outlet flow control device. 
     
     
         8 . The process of  claim 6 , wherein independently controlling comprises controlling the speed of the compressor 
     
     
         9 . The process of  claim 6 , wherein independently controlling comprises increasing the speed of the compressor or decreasing the speed of the compressor or shutting off the compressor. 
     
     
         10 . The process of  claim 7 , wherein independently controlling comprises independently controlling the at least one outlet flow control device comprising a hot gas bypass. 
     
     
         11 . The process of  claim 7 , wherein independently controlling comprises independently controlling a position of at least one inlet flow control device. 
     
     
         12 . The process of  claim 11 , wherein independently controlling comprises independently controlling a position of any one of the following inlet flow control devices comprising: dampers, extractors, grilles, valves, and inlet guide vanes. 
     
     
         13 . A heating, ventilation and air conditioning system, comprising:
 an evaporator;   a condenser;   a compressor having an inlet and an outlet;   at least one flow control device in communication with the inlet or the outlet or both the inlet and the outlet; and   a controller programmed with information corresponding to a performance parameter indicative of onset of surge, and adapted to independently control at least any one of the following: the compressor or at least one flow control device or both the compressor and the at least one flow control device, and mitigate an onset of surge.   
     
     
         14 . The heating, ventilation and air conditioning system of  claim 13 , wherein the controller is programmed to:
 measure a first pressure of the heating, ventilation and air conditioning system at a location upstream from the compressor;   measure a second pressure of the heating, ventilation and air conditioning system at a location downstream from the compressor;   determine a pressure ratio indicative of the onset of surge;   determine a surge line of the heating, ventilation and air conditioning system based upon the pressure ratio; and   independently control the at least one flow control device based upon the pressure ratio to mitigate the onset of the surge.   
     
     
         15 . The heating, ventilation and air conditioning system of  claim 13 , wherein controller is programmed to:
 calculate a first saturation temperature at a location upstream from the compressor;   calculate a second saturation temperature at a location downstream from the compressor; and   determine a saturation temperature difference indicative of the onset of surge;   determine a surge line of the heating, ventilation and air conditioning system based upon the saturation temperature difference; and   independently control the at least one flow control device based upon the saturation temperature difference to mitigate the onset of the surge.   
     
     
         16 . The heating, ventilation and air conditioning system of  claim 13 , wherein the controller is programmed to:
 calculate a head of the compressor;   determine a head measurement indicative of the onset of surge;   determine a surge line based upon the head; and   independently control the at least one flow control device based upon the head to mitigate the onset of the surge.   
     
     
         17 . The heating, ventilation and air conditioning system of  claim 13 , wherein the controller is programmed to:
 calculate a first saturation pressure at a location upstream of the compressor;   calculate a second saturation pressure at a location downstream of the compressor; and   determine a saturation pressure difference indicative of the onset of surge;   determine a surge line based upon the saturation pressure difference; and   independently control the at least one flow control device based upon the saturation pressure difference to mitigate the onset of the surge.   
     
     
         18 . The heating, ventilation and air conditioning system of  claim 13 , wherein the compressor comprises any one of the following: a fixed-speed compressor or a variable-speed compressor. 
     
     
         19 . The heating, ventilation and air conditioning system of  claim 13 , wherein the compressor comprises any one of the following: a centrifugal compressor or an axial compressor 
     
     
         20 . The heating, ventilation and air conditioning system of  claim 13 , wherein at least one flow control device comprises any one of the following: an inlet flow control device or an outlet flow control device or both an inlet flow control device and an outlet flow control device. 
     
     
         21 . The heating, ventilation and air conditioning system of  claim 20 , wherein the inlet flow control device comprises any one of the following: dampers, extractors, grilles, valves, and inlet guide vanes. 
     
     
         22 . The heating, ventilation and air conditioning system of  claim 20 , wherein the outlet flow control device comprises any one of the following: a variable geometry diffuser or a hot gas by-pass.