Patent Publication Number: US-2023134449-A1

Title: System and method for automatically cleaning refrigeration coils

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 62/898708 filed on Sep. 11, 2019. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to refrigeration systems for transportation containers, and more specifically to a system and method for automatically cleaning condenser coils in a refrigerated transportation container. 
     BACKGROUND 
     Transportation containers, such as those used in trans-oceanic shipping and similar shipping environments are typically designed with relatively uniform exterior dimensions for ease of shipping. In some cases the shipping means, such as cargo ship, can take long periods of time to transport the container. Some goods that are shipped in the containers are required to be maintained within a temperature controlled environment in order to prevent damage or spoilage. In such cases refrigeration systems are included in the interior of the transportation container. Due to the configuration of the refrigeration systems, they can be difficult to access during the shipping process, and maintenance is typically performed after unloading and before re-loading the transportation container. 
     Certain shipping environments, such as cargo vessels, can expose the transportation container to substantial amounts of contaminants and debris. This debris can be ingested by the refrigeration system and can cause a decrease in performance of the refrigeration system. Due to the access difficulties, as well as the practical realities of shipping systems, existing refrigerated transportation containers can be difficult to repair or clean during transportation. 
     SUMMARY OF THE INVENTION 
     In one example, a method for cleaning a refrigeration coil of a refrigerated transportation container includes detecting an indication of operational deterioration of a transportation container refrigeration system using a controller, reversing a rotational direction of an airflow fan from a first direction to a second direction such that air is drawn over a refrigeration coil and expelled from the transportation container using the airflow fan, and reverting the rotational direction of the airflow fan to the first direction at a conclusion of a cleaning operation. 
     In another example of the above method, the indication of operational deterioration is a refrigeration system pressure drop detected by a sensor. 
     In another example of any of the above methods, the indication of operational deterioration is an increase in a steady temperature of the transportation container detected by a sensor. 
     In another example of any of the above methods, the indication of operational deterioration is a manually applied trigger. 
     In another example of any of the above methods, reversing the rotational direction of the airflow fan further comprising increasing a speed of the airflow fan, thereby creating a burst of airflow. 
     In another example of any of the above methods, increasing the speed comprising maintaining the increased speed until the step of reverting the rotational direction of the airflow fan. 
     In another example of any of the above methods, increasing the speed comprises iteratively increasing and decreasing the speed of the fan, thereby pulsing an airflow through the airflow fan. 
     In another example of any of the above methods, the conclusion of the cleaning operation is defined by a predetermined duration. 
     In another example of any of the above methods, wherein reversing the rotational direction of an airflow fan further comprises activating a spray nozzle, and spraying a liquid onto the refrigeration coil. 
     In another example of any of the above methods, the indication of operational deterioration is a self-cleaning operation required signal from a telematics device. 
     In one example, a transportation container includes a storage volume, a refrigeration system contained within the storage volume, the refrigeration system including a fan configured to ingest exterior air, a condenser coil immediately downstream of the fan, and a vent configured exhaust spent cooling air from the storage volume, a controller configured to control the refrigeration system, the controller including instructions configured to cause the refrigeration system to detect an indication of operational deterioration of a transportation container refrigeration system, reverse a rotational direction of an airflow fan from a first direction to a second direction such that air is drawn over a refrigeration coil and expelled from the transportation container using the airflow fan, and revert the rotational direction of the airflow fan to the first direction at a conclusion of a cleaning operation. 
     In another example, the above transportation container includes at least one fluid spray nozzle disposed downstream of the condenser coil, relative to a direction of airflow during cooling operations. 
     In another example of any of the above transportation containers, the spray nozzle is connected to at least one of a water source and a cleaner source. 
     In another example, any above transportation container includes at least one of a condenser coil pressure sensor disposed at the condenser coil and a container temperature sensor. 
     In another example of any of the above transportation containers, reversing the rotational direction of the airflow fan further includes increasing a speed of the airflow fan, thereby creating a burst of airflow. 
     In another example of any of the above transportation containers, increasing the speed includes maintaining the increased speed until the step of reverting the rotational direction of the airflow fan. 
     In another example of any of the above transportation containers, increasing the speed includes iteratively increasing and decreasing the speed of the fan, thereby pulsing an airflow through the airflow fan. 
     In another example of any of the above transportation containers, the controller is configured to be connected to at least one self-cleaning operation manual activation system. 
     In another example of any of the above transportation containers, the controller is directly connected to the manual activation system. 
     In another example of any of the above transportation containers, the controller is connected to the manual activation system through at least one intermediary controller. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically illustrates an exemplary refrigerated transportation container. 
         FIG.  2    schematically illustrates a refrigeration system isolated from the refrigerated transportation container, according to one example. 
         FIG.  3    schematically illustrates a method for operating the refrigeration system of  FIG.  2    to automatically clean condenser coils . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    schematically illustrates a refrigerated transportation container  10  including a refrigeration system  20 . The refrigeration system  20  includes a fan  22  configured to ingest external air during standard operations. The air ingested by the fan  22  is passed over a heat exchanger  24  (such as a condenser coil). As the air passes over the heat exchanger  24 , the air removes heat from the refrigerant, thereby cooling the refrigerant. The heat removed from the refrigerant is exhausted through a grille to ambient, and the fan  22  ensures that air continues to circulate through across the heat exchanger  24 . The exemplary refrigeration system  20  in the illustrated example is simplified, and a practical implementation can include additional elements and controls according to any conventional refrigeration system. Operations of the refrigeration system  20  are controlled via a controller  50  according to any control scheme. The controller  50  in some examples includes a transmitter and receiver configured to communicate with a central controller, thereby allowing transport vessel personnel to indirectly interact with the controller  50  using a control system of the transport vessel. 
     During operation of the refrigeration system  20 , the air ingested through the fan  22  can include contaminants. By way of example, the contaminants can include dirt, dust, grime, oil, or any similar external material capable of being entrained in the airflow. The entrained contaminants can build up on internal components of the refrigeration system  10 , such as the heat exchanger  24  and negatively impacting the performance of the refrigeration system  10 . 
     In the example of  FIG.  1   , the controller  50  includes a memory storing operational instructions. The operational instructions are configured to cause the controller  50  to provide predetermined response actions to conditions from the refrigeration system  20 . By way of example, if the temperature within the refrigerated transport container  10  increases above a threshold, the operational instructions can cause the refrigeration system  20  to decrease the temperature of the heat exchanger  24 , and the temperature of the container  10  is reduced. 
     One response operation that is stored within the controller  50  is a self-cleaning operation directed to cleaning/removing the buildup of contaminants from the condenser coils  24 . In a general operation, when one or more sensors indicates that refrigeration operations are being negatively impacted (deteriorated) within the transportation container  10 , the controller  50  is configured to compare the type deterioration to a predefined list of probable causes of the deterioration. When the probable cause of deterioration is a buildup of contaminants within the refrigeration system  20 , the controller  50  is configured to respond by initiating the self-cleaning operation. 
     With continued reference to  FIG.  1   ,  FIG.  2    schematically illustrates an exemplary simplified refrigeration system  100 , such as could be used in the transportation container  10  of  FIG.  1   . The simplified refrigeration system  100  includes a fan  110 . The fan  110  ingests an airflow  112  during standard rotation, and passes the airflow  112  over a condenser coil  120 . The condenser coil  120  includes an input  122  and an output  124 , each of which connects to a conventional refrigerant system and provides a constant source of cooled refrigerant to the condenser coil  120 . As the air passes over the condenser coil  120 , the air is cooled and expelled into the storage volume  30  (illustrated in  FIG.  1   ) of the transportation container. 
     A controller  130  with a processors  132  and a memory  134  is connected to the fan  110 , and the refrigerant system  100 . The controller  130  is configured to control both the fan  110  and the refrigerant system  100  according to any conventional control schemes. In addition, multiple sensors  142 ,  144 ,  146  are connected to the controller  130 . In the illustrated example, the first sensor  142  is a fan inlet sensor  142 , the second sensor  144  is a condenser coil pressure sensor  144 , and the third sensor  146  is a storage volume temperature sensor  146 . In addition to the sensors  142 ,  144 ,  146  a manual activation system  160  is connected to the controller and allows an operator to manually activate the self-cleaning operation. In some examples the manual activation system  160  can be a dedicated button or toggle on the container  10  itself. In alternative systems, the manual activation system  160  can be a component of an overall system controller, or other general control systems. 
     Included immediately downstream of the condenser coil  120  is a spray nozzle  150 . The spray nozzle  150  is fluidly connected to a water source via a connection  152 . The spray nozzle  150  is oriented towards the condenser coil  120 , and is configured to spray water from the nozzle  150  onto the condenser coil  120  during all, or part, of the self-cleaning operation. In alternative examples, the spray nozzle  150  can be connected to another fluid, such as a solvent or cleanser, instead of or in addition to the water described above. 
     The fan  110  is configured such that the controller  130  can reverse the rotational direction of the fan blades during the self-cleaning operation. Reversing the direction of the fan blades reverses the direction of the airflow, and assists in the self-cleaning operation by expelling the contaminants from the condenser coil  120  area through the fan  110 . 
     With continued reference to the transportation container  10  of  FIG.  1   , and the refrigeration system  100  of  FIG.  2   ,  FIG.  3    illustrates a method  200  for automatically cleaning a refrigeration system. Initially, the controller  50 ,  130  detects an indication of a deterioration of at least one operational parameter in a “Detect Operational Deterioration” step  210 . In some examples, the indication can be an increase in condenser coil pressure detected via a condenser coil pressure sensor  144 . In another example, the indication can be an alarm indication from a control system. In another example the indication can be a rise in condenser motor current. In another example, the indication of deterioration can be an increase in a steady temperature of the storage volume  30  of the transportation container as detected by the storage volume  30  temperature sensor  146 . In another example, the indication of operational deterioration can be a manual signal provided by an operator activating the manual activation system  160 . 
     In yet further examples, the indication can be provided by an operator using the manual activation system  160  in response to one or more warning indicators provided through the controller  130  to a general control or alert system. 
     In yet further examples, the indication may be an alarm provided by the controller in response to a telematics device signaling that a self-cleaning operation is required. 
     In yet further examples, the indication can be any combination of the aforementioned indicators, or a combination of the aforementioned indicators with at least one additional sensed or detected factor. 
     Once the controller  50 ,  130  receives the indication of operational deterioration, the controller  50 ,  130 , begins the self-cleaning operation by removing power from (i.e. disabling) the non-fan components of the refrigeration system and reversing the rotational direction of the fan  22 ,  110  in a “Reverse Direction of Fan” step  220 . In a basic self-cleaning operation, the rotational direction is simply reversed, and the fan  22 ,  110  is operated in reverse for a predetermined period of time. In such an example, reversal of the direction of airflow through the refrigeration system will dislodge loose or light dust and other contaminants and drive the contaminants out of the refrigeration system through the fan  22 ,  110 . 
     In another example, such as one where heavy, or sticky, contaminants are expected to be present, the fan  22 ,  110  can be operated in a pulsing manner by rapidly increasing and decreasing the rotational speed while the fan  22 ,  110  is rotating in the reverse direction. The rapid increases and decreases in speed create air pulses that further help dislodge contaminants from the refrigerator coil, or other portions of the refrigeration system. In yet another example, the speed of the fan  22 ,  110  can be suddenly increased a single time to create an initial pulse disturbing the contaminants. After the initial burst the speed of the fan can either be reverted to the standard operational speed, or maintained at the increased levels. 
     In another example, the spray nozzle  150  is activated either simultaneously with, or shortly after, reversing the rotational direction of the fan  22 ,  110 . The activation of the spray nozzle sprays water, a cleaner/solvent, or a mixture of the two onto the refrigeration coil while the fan  22 ,  110  is rotating in the reverse direction. The fluid from the spray nozzle dislodges contaminants and the reversed airflow removes the contaminants and the fluid from the refrigeration system. 
     While described as distinct examples above, it is understood that any given self-cleaning operation can include some or all of the steady airflow, pulsed airflow, and spray nozzle. And each of the steady airflow, pulsed airflow, and spray nozzle operations can be operated for only a part or for all of the self-cleaning operation. 
     Once a predetermined duration for the self-cleaning operation has elapsed, the controller  22 ,  130  reverts the rotational direction of the fan  22 ,  130  to the standard rotational direction in a “Return to Standard Operations” step  230 . 
     It is further understood that any of the above described concepts can be used alone or in combination with any or all of the other above described concepts. Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.