Forced air thermal energy storage system

Abstract

A system including a chilled air generation system, a forced air convection system, one or more phase change material (PCM) modules, and a controller. The controller is configured to regulate the temperature of a facility by selectively utilizing the chilled air generation system and the forced air convection system based on multiple factors, which may include energy source type(s), relative costs of the energy from the source(s), availability of energy from the source(s), facility temperature, PCM module temperature, and/or temperature of goods stored within the facility, among other considerations. The controller may thus advantageously and cost-effectively control the periods of time during which the chilled air generation system is used and those during which the thermal energy stored in the PCM modules is used.

What is claimed is: 
     
         1 . A system, comprising:
 a forced air convection system configured to:
 provide a chilled airflow from a chilled air generation system during a first period of time; and 
 generate a convective airflow during a second period of time; 
   one or more phase change material (PCM) modules for thermal energy storage, each comprising a phase change material, wherein the PCM module(s) is(are) configured to exchange heat with the convective airflow and the chilled airflow; and   a controller configured to determine the second period of time based, at least in part, on the first period of time.   
     
     
         2 . The system of  claim 1 , wherein the PCM module(s) is(are) configured to be mounted to a ceiling of a facility, a wall of a facility, or a rack of a facility, respectively. 
     
     
         3 . The system of  claim 1 ,
 wherein the PCM module is configured to be mounted to a rack of a facility,   wherein the rack is structure on which goods may be disposed.   
     
     
         4 . The system of  claim 3 , wherein the forced air convection system is disposed at a higher elevation than the PCM module on the rack. 
     
     
         5 . The system of claim I, wherein the PCM has a solid to liquid phase transition temperature or temperature range such that heat exchange between the convective airflow and the PCM module causes a portion of the phase change material of the PCM module to undergo a solid to liquid phase transition. 
     
     
         6 . The system of  claim 1 , wherein the PCM has a liquid to solid phase transition temperature or temperature range such that heat exchange between the chilled airflow and the PCM module causes a portion of the phase change material of the PCM module to undergo a liquid to solid phase transition. 
     
     
         7 . The system of  claim 6 , wherein the convective airflow and the chilled airflow are different airflows, and wherein the first period of time is different than the second period of time. 
     
     
         8 . The system of  claim 6 , wherein the PCM has a liquid to solid phase transition that occurs below a freezing temperature of water. 
     
     
         9 . The system of  claim 8 , wherein the PCM has a solid to liquid phase transition that occurs at a temperature below a freezing temperature of water. 
     
     
         10 . The system of  claim 2 , wherein the facility is a walk in freezer, a walk in refrigerator, a room of a building, a cargo container, a shipping container, a refrigerated food transport vehicle, a trailer, a trailer of a tractor unit, a ship, an airplane, or a rail car. 
     
     
         11 . The system of  claim 2 , further comprising a sensor to measure an ambient temperature of the facility. 
     
     
         12 . The system of  claim 2 , further comprising a sensor to measure a temperature of a good disposed within the facility. 
     
     
         13 . The system of  claim 1 , further comprising a sensor to measure a temperature of the PCM module or the phase change material disposed within a PCM module. 
     
     
         14 . The system of claim I, wherein the controller is further configured to:
 send a command to the chilled air generation system during the second period of time that activates the chilled air generation system that generates the chilled airflow;   activate a reversible fan module of the forced air convection system in a first direction during the second period of time;   send a second command to the chilled air generation system that deactivates the chilled air generation system during the first period of time; and   activate the reversible fan module of the forced air convection system in a second direction during the first period of time.   
     
     
         15 . The system of  claim 14 , wherein the controller is configured to determine when to activate and deactivate the chilled air generation system based on a cost of electricity, wherein the cost of electricity during the second period of time is less than a cost of electricity during the first period of time. 
     
     
         16 . The system of  claim 15 , wherein the controller is configured to determine when to activate and deactivate the chilled air generation system based on an availability of electricity from a renewable power source, wherein the electricity from the renewable power source is available during the second period of time. 
     
     
         17 . The system of  claim 14 , further comprising a renewable energy source configured to supply power to the chilled air generation system and the forced air convection system during the second period of time. 
     
     
         18 . The system of  claim 17 , further comprising an on-demand energy source configured to supply power to the forced air convection system during the first period of time. 
     
     
         19 . The system of  claim 17 , further comprising a battery backup configured to supply power to the forced air convection system during the first period of time. 
     
     
         20 . The system of  claim 14 , wherein power is not available from an on-demand source during the first period. 
     
     
         21 . The system of  claim 17 , wherein power is available from an on-demand source during the second period. 
     
     
         22 . A system, comprising:
 a facility having an internal area;   a forced air convection system configured to generate a convective airflow within the internal area of the facility:   a chilled air generation system for periodically supplying a chilled airflow to the internal area of the facility;   one or more phase change material (PCM) modules, each comprising a phase change material, wherein the PCM module(s) is(are) configured to exchange heat with air in the internal area; and   a controller configured to determine:
 a first time period or periods during which to operate the forced air convection system; and 
 a second time period or periods during which to operate the chilled air generation system; 
 wherein the controller is configured to determine the respective time periods based on:
 one or more of a temperature of the air within the internal area of the facility, a temperature of a good stored within the facility, or a temperature of the phase change material or the PCM modules; and 
 a cost and/or availability of electricity from a power supply. 
 
   
     
     
         23 . The system of  claim 22 , wherein the power supply comprises one or more of an on-demand power source, a renewable power source, or a battery backup. 
     
     
         24 . The system of  claim 22 , wherein the chilled air generation system is configured to provide chilled air at a temperature lower than a phase transition temperature of the phase change material (PCM), wherein:
 the PCM has a liquid to solid phase transition temperature or temperature range such that heat exchange between the chilled airflow and the PCM module causes a portion of the phase change material of the PCM module to undergo a liquid to solid phase transition; and   the PCM has a solid to liquid phase transition temperature or temperature range such that, as the temperature within the facility increases, heat exchange between the convective airflow and the PCM module causes a portion of the phase change material of the PCM module to undergo a solid to liquid phase transition, thereby regulating a temperature of the air within the facility.   
     
     
         25 . The system of  claim 22 , wherein the controller is configured to operate the chilled air generation system:
 during periods of low relative cost of electricity from an on-demand power supply; or   during periods when power is available from a renewable power source.   
     
     
         26 . The system of  claim 25 , wherein the controller is configured to operate the forced air convection system and regulate temperature within the facility via heat exchange between the air and the PCM modules:
 during periods of high relative cost of electricity from an on-demand power supply; or   during periods when power is not available from a renewable power source; or   during periods when power is available from a battery backup.   
     
     
         27 . The system of  claim 26 , wherein the controller is further configured to activate the forced air convection system at a first temperature threshold and to activate the chilled air generation system at a second temperature threshold. 
     
     
         28 . The system of  claim 27 , wherein the controller is configured to:
 send a command to the chilled air generation system during the second time period that activates the chilled air generation system that generates the chilled airflow;   activate a reversible fan module of the forced air convection system in a first direction during the second time period;   send a second command to the chilled air generation system that deactivates the chilled air generation system during the first time period; and   activate the reversible fan module of the forced air convection system in a second direction during the first time period.