Auto-defrost system in actively cooled tote

Abstract

Systems and methods for automatic defrosting of an actively cooled tote are provided. In some embodiments, a method of operating an actively cooled container includes: determining to initiate a defrost cycle for the actively cooled container; deactivating a cooling system of the actively cooled container; activating a defrost heater of the actively cooled container; determining to deactivate the defrost heater of the actively cooled container; setting the defrost heater to maintain a temperature of a thermal accept system at a threshold; waiting a set duration of time to allow for melted frost to drip into a collection tray; and activating the cooling system of the actively cooled container.

What is claimed is: 
     
         1 . A method of operating an actively cooled container, comprising:
 determining to initiate a defrost cycle for the actively cooled container;   deactivating a cooling system of the actively cooled container;   activating a defrost heater of the actively cooled container;   determining to deactivate the defrost heater of the actively cooled container;   setting the defrost heater to maintain a temperature of a thermal accept system at a threshold;   waiting a set duration of time to allow for melted frost to drip into a collection tray; and   activating the cooling system of the actively cooled container.   
     
     
         2 . The method of  claim 1  further comprising:
 deactivating one or more fans of the actively cooled container. 
 
     
     
         3 . The method of  claim 1  further comprising, after waiting the set duration of time:
 activating one or more fans of the actively cooled container. 
 
     
     
         4 . The method of  claim 3  wherein activating the one or more fans comprises:
 in response to determining that the temperature of the thermal accept system is at or below a set threshold temperature, activating one or more fans of the thermal accept system. 
 
     
     
         5 . The method of  claim 4  wherein the set threshold temperature is zero Celsius. 
     
     
         6 . The method of  claim 1  wherein determining to deactivate the defrost heater comprises one or more of:
 determining that the defrost heater has been activated for a predetermined amount of time; 
 deactivating that a temperature of a thermal accept system crosses above a set threshold. 
 
     
     
         7 . The method of  claim 1  wherein determining to initiate a defrost cycle comprises one or more of:
 reaching an elapsed time since prior defrost; 
 determining that a difference between an accept temperature and a chamber temperature exceeds a specified value; 
 determining that a lid open duration and subsequent full-power operation ratio exceeds a specified value; 
 determining a relative humidity of the actively cooled container; and 
 determining a mass of frost currently on the heat exchanger. 
 
     
     
         8 . The method of  claim 1  further comprising:
 activating an alarm indicating that frost may have built up. 
 
     
     
         9 . The method of  claim 1  further comprising:
 determining that a threshold number of defrost cycles have been performed. 
 
     
     
         10 . The method of  claim 1  further comprising:
 ensuring that the temperature of the actively cooled container does not rise above an allowable limit. 
 
     
     
         11 . An actively cooled container, comprising:
 a cooling system;   one or more fans;   a collection tray; and   a controller; the controller operable to:
 determine to initiate a defrost cycle for the actively cooled container; 
 deactivate a cooling system of the actively cooled container; 
 activate a defrost heater of the actively cooled container; 
 determine to deactivate the defrost heater of the actively cooled container; 
 set the defrost heater to maintain a temperature of a thermal accept system at a threshold; 
 wait a set duration of time to allow for melted frost to drip into the collection tray; and 
 activate the cooling system of the actively cooled container. 
   
     
     
         12 . The method of  claim 11  wherein the controller is further operable to:
 deactivate one or more fans of the actively cooled container. 
 
     
     
         13 . The method of  claim 11  wherein the controller is further operable to, after waiting the set duration of time:
 activate one or more fans of the actively cooled container. 
 
     
     
         14 . The method of  claim 13  wherein being operable to activate the one or more fans comprises being operable to:
 in response to determining that the temperature of the thermal accept system is at or below a set threshold temperature, activate one or more fans of the thermal accept system. 
 
     
     
         15 . The method of  claim 14  wherein the set threshold temperature is zero Celsius. 
     
     
         16 . The method of  claim 11  wherein being operable to determine to deactivate the defrost heater comprises being operable to perform one or more of:
 determine that the defrost heater has been activated for a predetermined amount of time; 
 deactivate that a temperature of a thermal accept system crosses above a set threshold. 
 
     
     
         17 . The method of  claim 11  wherein being operable to determine to initiate a defrost cycle comprises being operable to perform one or more of:
 reach an elapsed time since prior defrost; 
 determine that a difference between an accept temperature and a chamber temperature exceeds a specified value; 
 determine that a lid open duration and subsequent full-power operation ratio exceeds a specified value; 
 determine a relative humidity of the actively cooled container; and 
 determine a mass of frost currently on the heat exchanger. 
 
     
     
         18 . The method of  claim 11  wherein the controller is further operable to:
 activate an alarm indicating that frost may have built up. 
 
     
     
         19 . The method of  claim 11  wherein the controller is further operable to:
 determine that a threshold number of defrost cycles have been performed. 
 
     
     
         20 . The method of  claim 11  wherein the controller is further operable to:
 ensure that the temperature of the actively cooled container does not rise above an allowable limit.