Building temperature control system and method

Abstract

A method and system of dynamically controlling a temperature control system that has at least one compressor and is operable in a plurality of stages. The method includes iteratively determining, for each of the plurality of stages, a plurality of intermediate air-related conditions and system operating conditions based on sensed conditions. The method also includes identifying a stage among the plurality of stages, and updating an initial supply air temperature set point with a supply air temperature set point corresponding to the identified stage.

1 . A method of dynamically controlling a temperature control system including a compressor and being operable in a plurality of stages, the method comprising: 
 modulating the compressor based on an initial supply air temperature set point;    determining a first plurality of air-related conditions and system operating conditions;    iteratively determining, for at least some of the plurality of stages, a plurality of intermediate air-related conditions and system operating conditions based on the determined first plurality of conditions;    identifying an iteration among the plurality of stages; and    updating the initial supply air temperature set point with a supply air temperature set point corresponding to the identified stage.    
   
   
       2 . The method of  claim 1 , wherein the air-related conditions comprise at least one of an outside air temperature, a mixed air temperature, a mixed air relative humidity, an outlet air temperature, an outlet air humidity, an outlet air pressure, a mixed air humidity ratio, an air density, an air specific heat, a fan head, a mixed air enthalpy, and an outside air enthalpy.  
   
   
       3 . The method of  claim 1 , wherein the system operating conditions comprise at least one of a fan speed, a fan air flow rate, a fan power, and a compressor cooling capacity.  
   
   
       4 . The method of  claim 1 , wherein identifying an iteration comprises comparing at least some of the intermediate conditions with a plurality of corresponding thresholds.  
   
   
       5 . The method of  claim 4 , wherein the intermediate conditions comprise a fan flow rate, a mixed air temperature, and a mixed humidity ratio, and the thresholds comprise a minimum fan flow rate, a mixed air temperature set point, and a mixed air humidity set point, wherein the comparing comprises: 
 determining the minimum fan flow rate from the fan flow rates for all stages;    comparing the fan flow rate of a first stage with the minimum fan flow rate;    comparing the mixed air temperature of a stage with the mixed air temperature set point;    determining the mixed humidity ratio for a stage;    comparing the mixed humidity ratio with the mixed air humidity set point; and    disabling the compressor when the fan flow rate of the first stage is less than the minimum fan flow rate, when the mixed air temperature of the stage is less than the mixed air temperature set point, and when the mixed humidity ratio is less than the mixed air humidity set point.    
   
   
       6 . The method of  claim 4 , wherein the intermediate conditions comprise a fan flow rate and the thresholds comprise a minimum fan flow rate, wherein the comparing comprises: 
 comparing the fan flow rate of a stage with the minimum fan flow rate; and    rejecting the stage when the fan flow rate of the stage is less than the minimum fan flow rate.    
   
   
       7 . The method of  claim 4 , wherein the intermediate conditions comprise a supply air temperature and the thresholds comprise a minimum supply air temperature, wherein the comparing comprises: 
 comparing the supply air temperature of a stage with the minimum supply air temperature; and    rejecting the stage when the supply air temperature of the stage is less than the minimum supply air temperature.    
   
   
       8 . The method of  claim 4 , further comprising adjusting an outside air valve based on the comparing.  
   
   
       9 . The method of  claim 8 , wherein adjusting an outside air valve comprises: 
 reducing an air volume entering the valve; and    increasing the air volume entering the valve.    
   
   
       10 . The method of  claim 1 , wherein iteratively determining a plurality of intermediate conditions comprises: 
 initializing the intermediate air-related conditions and system operating conditions; and    iteratively determining a supply air temperature set point for each of the plurality of stages.    
   
   
       11 . The method of  claim 10 , further comprising: 
 determining a supply air temperature humidity ratio for each of the plurality of stages based on the iteratively determined supply air temperature set point;    determining a mixed air temperature, a supply air temperature, an outside air temperature, and an airflow rate;    determining a cooling capacity based on the mixed air temperature, the supply air temperature, the outside air temperature, and the airflow rate;    determining a supply air enthalpy based on the iteratively determined supply air temperature set point and the supply air temperature humidity ratio;    determining a room temperature; and    determining a subsequent supply air temperature set point based on the room temperature, the supply air enthalpy, and the supply air temperature humidity ratio.    
   
   
       12 . The method of  claim 1 , wherein determining the first plurality of conditions comprises sensing at least some of the conditions using at least one sensor.  
   
   
       13 . A controller for dynamically controlling a temperature control system including a compressor and being operable in a plurality of stages, the temperature control system being operable to cool air in a location and further including a modulator configured to modulate the compressor based on an initial supply air temperature set point and a plurality of sensors operable to sense a plurality of air-related conditions and system operating conditions, the controller comprising: 
 an iteration module operable to iteratively determine, for at least some of the plurality of stages, a plurality of intermediate air-related conditions and system operating conditions based on the sensed conditions;    an identifier module operable to identify a stage among the plurality of stages; and    an updater module configured to update the initial supply air temperature set point with a supply air temperature set point corresponding to the identified stage.    
   
   
       14 . The controller of  claim 13 , further comprising a comparator module configured to compare at least some of the intermediate conditions with a plurality of corresponding thresholds, wherein the identifier module is further configured to identify the stage based on at least one comparison of the comparator module.  
   
   
       15 . The controller of  claim 14 , wherein the intermediate conditions comprise a fan flow rate and the thresholds comprise a minimum fan flow rate, wherein the comparator module is further configured to compare the fan flow rate of a stage with the minimum fan flow rate, the controller further comprising a rejector module configured to reject the stage when the fan flow rate of the stage is less than the minimum fan flow rate.  
   
   
       16 . The controller of  claim 14 , wherein the intermediate conditions comprise a supply air temperature and the thresholds comprise a minimum supply air temperature, wherein the comparator module is further configured to compare the supply air temperature of the stage with the minimum supply air temperature, the controller further comprising a rejector module configured to reject the stage when the supply air temperature of the stage is less than the minimum supply air temperature.  
   
   
       17 . The controller of  claim 13 , further comprising an initialization module configured to initialize the intermediate air-related conditions and system operating conditions.  
   
   
       18 . The controller of  claim 13 , wherein the sensed conditions comprise a mixed air temperature, a supply air temperature, an outside air temperature, and a room temperature, the controller further comprising: 
 a humidity ratio module configured to determine a supply air temperature humidity ratio for at least some of the plurality of stages based on the iteratively determined supply air temperature set point;    a flow rate module configured to determine an airflow rate;    a cooling capacity module configured to determine a cooling capacity based on the mixed air temperature, the supply air temperature, the outside air temperature, and the airflow rate; and    an energy module configured to determine an supply air enthalpy based on the iteratively determined supply air temperature set point and the supply air temperature humidity ratio,    wherein the iteration module is further configured to determine a supply air temperature set point based on the room temperature, the supply air enthalpy, and the supply air temperature humidity ratio.    
   
   
       19 . The controller of  claim 13 , wherein the controller is a retrofitted component in the temperature control system, the temperature control system further including a main controller that is different from the controller.