Preventing icing in an hvac system

Abstract

A method of operating a heating, ventilation, and air conditioning (HVAC) system includes monitoring a parameter of the HVAC system associated with a temperature of a refrigerant at a heat exchanger, determining if the HVAC system is in an operating condition associated with frost accumulation at the heat exchanger, and adjusting a flow rate of an airflow across the heat exchanger in response to determining that the HVAC system is in the operating condition associated with frost accumulation at the heat exchanger.

What is claimed is: 
     
         1 . A method of operating a heating, ventilation, and air conditioning (HVAC) system comprising:
 monitoring a parameter of the HVAC system associated with a temperature of a refrigerant at a heat exchanger;   determining if the HVAC system is in an operating condition associated with frost accumulation at the heat exchanger; and   adjusting a flow rate of an airflow across the heat exchanger in response to determining that the HVAC system is in the operating condition associated with frost accumulation at the heat exchanger.   
     
     
         2 . The method of  claim 1 , wherein determining if the HVAC system is in the operating condition associated with frost accumulation at the heat exchanger further comprises comparing the parameter to a threshold. 
     
     
         3 . The method of  claim 2 , wherein when the parameter exceeds the threshold, the HVAC system is not in the operating condition associated with frost accumulation at the heat exchanger. 
     
     
         4 . The method of  claim 2 , wherein when the parameter is equal to or below the threshold, the HVAC system is in the operating condition associated with frost accumulation at the heat exchanger. 
     
     
         5 . The method of  claim 1 , wherein adjusting the flow rate of the airflow across the heat exchanger further comprises increasing the flow rate of the airflow. 
     
     
         6 . The method of  claim 5 , wherein the flow rate of the airflow is increased by a fixed percentage. 
     
     
         7 . The method of  claim 5 , wherein the flow rate of the airflow is incrementally increased until the HVAC system is not in the operating condition associated with frost accumulation at the heat exchanger. 
     
     
         8 . The method of  claim 1 , wherein the HVAC system comprises a compressor and the parameter is a saturated suction temperature. 
     
     
         9 . The method of  claim 8 , wherein monitoring the parameter of the HVAC system associated with the temperature of the refrigerant at the heat exchanger comprises sensing a temperature between an exit of an evaporator and an inlet of the compressor. 
     
     
         10 . The method of  claim 8 , wherein monitoring the parameter of the HVAC system associated with the temperature of the refrigerant at the heat exchanger further comprises sensing a pressure between an exit of an evaporator and an inlet of the compressor. 
     
     
         11 . The method of  claim 1 , wherein the parameter is the temperature of the refrigerant within the heat exchanger. 
     
     
         12 . The method of  claim 1  further comprising:
 determining if the HVAC system having an adjusted flow rate of the airflow across the heat exchanger is in the operating condition associated with frost accumulation at the heat exchanger; and 
 adjusting the flow rate of the airflow across the heat exchanger in response to determining that the HVAC system is not in the operating condition associated with frost accumulation at the heat exchanger. 
 
     
     
         13 . The method of  claim 12 , wherein adjusting the flow rate of the airflow across the heat exchanger in response to determining that the HVAC system is not in the operating condition associated with frost accumulation at the heat exchanger further comprises reducing the flow rate of the airflow across the heat exchanger. 
     
     
         14 . A heating, ventilation, and air conditioning (HVAC) system, comprising:
 a closed loop circuit having refrigerant circulating therethrough, the closed loop circuit including a compressor and a heat exchanger;   a movement mechanism for moving an airflow across the heat exchanger;   a sensor operable to sense a parameter of the closed loop circuit; and   a controller operable to adjust a flow rate of the airflow across the heat exchanger in response to the parameter to maintain a temperature of the refrigerant at the heat exchanger above freezing.   
     
     
         15 . The HVAC system of  claim 14 , wherein the parameter is saturated suction temperature. 
     
     
         16 . The HVAC system of  claim 15 , wherein the saturated suction temperature is measured between an exit of the heat exchanger and an inlet of the compressor. 
     
     
         17 . The HVAC system of  claim 14 , wherein the parameter is pressure between an exit of the heat exchanger and an inlet of the compressor. 
     
     
         18 . The HVAC system of  claim 14 , wherein the controller is operable to increase the flow rate of the airflow across the heat exchanger when the parameter is equal to below a threshold. 
     
     
         19 . The HVAC system of  claim 18 , wherein the controller is operable to decrease the flow rate of the airflow across the heat exchanger when the parameter is equal to or exceeds a second threshold.