Auto cure variable fan drive control system and associated methods

Abstract

Methods and systems for controlling air characteristics for storage facilities. A controller and temperature sensors can detect an external temperature and compare it to a reference temperature. Depending on the relationship between the external temperature and the reference temperature (e.g. warmer or colder) the controller can initiate a burner, open an air intake, and operate fans to achieve desirable conditions within the facility efficiently.

1 . A method for controlling interior air temperature inside a crop storage facility, wherein a fan moves heated air from a burner in the storage facility and can draw air into the storage facility through an air intake, the method comprising:
 detecting a first temperature of air inside the storage facility;   comparing the first temperature to a second temperature;   if the first temperature is less than the second temperature, increasing an operating level of the burner;   if the first temperature is less than the second temperature and the burner level is at a predetermined maximum operating level, decreasing a fan output;   if the first temperature is less than the second temperature and the fan throughput is at a predetermined minimum level and the burner is at or above a predetermined maximum, at least partially closing the air intake; and   if the first temperature is less than the second temperature, the burner is at the predetermined maximum operating level, and the air intake is fully closed, recirculating the air inside the storage facility.   
     
     
         2 . The method of  claim 1 , further comprising controlling the fan output with a variable frequency drive. 
     
     
         3 . The method of  claim 1  wherein comparing the first temperature to the second temperature comprises comparing the first temperature to the second temperature at predefined time intervals. 
     
     
         4 . The method of  claim 3  wherein the predefined time intervals are between five and ten minutes. 
     
     
         5 . The method of  claim 1 , further comprising if the air intake is closed, periodically comparing temperature outside the facility to a predefined temperature. 
     
     
         6 . The method of  claim 1 , further comprising:
 after fully closing the air intake, periodically comparing the temperature outside the facility to a predefined temperature;   if the temperature outside the facility is greater than the predefined temperature, opening the air intake and increasing the fan output at each periodic comparison between the temperature outside the facility and the predefined temperature; and   if the air intake reaches a maximum open status, decrementing the burner operating level.   
     
     
         7 . A method for controlling air temperature in a crop storage facility, the method comprising:
 monitoring an external temperature;   comparing the external temperature to a first reference temperature;   if the external temperature is greater than the first reference temperature, opening an air intake door to the facility to permit external air to enter the facility and operating a burner at a first level;   with the air intake door open, monitoring a temperature within an air plenum of the facility;   if the temperature in the air plenum is below a second reference temperature, closing the air intake door and turning off the burner; and   if the temperature in the air plenum is above the second reference temperature, opening the air intake door.   
     
     
         8 . The method of  claim 7 , further comprising if the temperature in the air plenum is above the second reference temperature, reducing the level of the burner. 
     
     
         9 . The method of  claim 7  wherein opening an air intake door comprises operating a variable frequency drive fan. 
     
     
         10 . The method of  claim 7  wherein monitoring the external temperature and comparing the external temperature to the first reference temperature is performed by a controller. 
     
     
         11 . The method of  claim 7  wherein the storage facility contains perishable goods, and wherein the first reference temperature and the second reference temperature are dependent upon desirable conditions for the perishable goods. 
     
     
         12 . The method of  claim 11  wherein the perishable goods are at least one of onions or potatoes. 
     
     
         13 . The method of  claim 7  wherein monitoring the temperature within the air plenum comprises operating a plurality of sensors within the air plenum to detect temperature at a plurality of locations within the air plenum. 
     
     
         14 . The method of  claim 13  wherein monitoring the temperature within the air plenum comprises averaging the temperature from the plurality of sensors. 
     
     
         15 . The method of  claim 7  wherein initiating a burner at a high level comprises initiating the burner at a maximum level. 
     
     
         16 . A method for operating an air control system of a facility in a warm-to-cold operation, the air control having a burner, at least one fan, and an air intake, wherein the air control system is reversible between the warm-to-cold operation and a cold-to-warm operation, the method comprising:
 operating the air control system in a warm-to-cold operation;   comparing an interior air temperature of the facility to a reference temperature;   if the interior air temperature is greater than the reference temperature, reversing the air control system from the warm-to-cold operation to the cold-to-warm operation;   if the interior air temperature is less than the reference temperature, increasing the burner;   if the burner has reached a maximum operating state, and the interior air temperature is greater than the reference temperature, reversing the air control system from the warm-to-cold operation to the cold-to-warm operation;   if the burner has reached a maximum operating state and the interior air temperature is less than the reference temperature, reducing the fan;   if the fan has reached a minimum operating state, and the interior air temperature is greater than the reference temperature, reversing the air control system from the warm-to-cold operation to the warm-to-cold operation;   if the fan has reached a minimum operating state, and the interior air temperature is less than the reference temperature, at least partially closing the air intake; and   if the air intake is closed, entering a recirculation operation.   
     
     
         17 . The method of  claim 16 , further comprising recording an external temperature when entering the recirculation operation, and using the recorded external temperature as the reference temperature. 
     
     
         18 . The method of  claim 16  wherein the recirculation operation comprises an air treatment process using a closed circuit of air within the facility. 
     
     
         19 . The method of  claim 16 , further comprising comparing the interior air temperature to the reference temperature and identifying a difference between the interior air temperature and the reference number, the difference having a magnitude. 
     
     
         20 . The method of  claim 19  wherein reducing the fan comprises reducing the fan by an amount dependent upon the magnitude of the difference. 
     
     
         21 . The method of  claim 19  wherein increasing the burner comprises increasing the burner by an amount dependent upon the magnitude of the difference. 
     
     
         22 . The method of  claim 19  wherein closing the air intake comprises closing the air intake by an amount dependent upon the magnitude of the difference.