Surveillance of a plurality of refrigerated containers and determination of an insulation parameter of a refrigerated container

Abstract

A method is disclosed herein of managing a plurality of refrigerated containers (2), the method comprising the step of surveilling the insulation condition of said containers (2) by repeatedly determining an insulation parameter (Uact, Ucur) of each of the plurality of refrigerated containers (2). Furthermore is disclosed a method to determine an insulation parameter (Uact) of a refrigerated container (2), the method comprising at least the steps of—determining a refrigeration effect (QRef) caused by a refrigeration unit refrigerating the container (2), —calculating an actual rate of energy loss of the container (2) due to heat ingress from the ambient surroundings, —determining an actual temperature difference (ΔT) between the interior (8) of the container (2) and the ambient air, and—determining the actual insulation parameter (Uact) of the container (2) from the ratio of said actual rate of energy loss and said actual temperature difference.

What is claimed is: 
     
         1 . A method of managing a plurality of refrigerated containers, the method comprising the step of
 surveilling the insulation condition of said containers by repeatedly determining an insulation parameter of each of the plurality of refrigerated containers, wherein the insulation parameter of each of the plurality of containers is determined by means of the set point temperature of that container, the ambient temperature of that container and an energy consumption of that container.   
     
     
         2 . The method according to  claim 1 , further comprising the step of ranking the plurality of containers for suitable use thereof based on the determined insulation parameter or a model insulation parameter of the container. 
     
     
         3 . The method according to  claim 1 , further comprising the step of identifying which of the plurality of containers need maintenance based on the determined insulation parameter or a model insulation parameter of the container. 
     
     
         4 . The method according to  claim 1 , further comprising the step of determining of the placement of each of said plurality of containers in a ship based on the determined insulation parameter or a model insulation parameter. 
     
     
         5 . The method according to  claim 1 , further comprising the step of estimating the lifetime of each container based on the determined insulation parameter or a model insulation parameter of the container. 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . A method to determine an insulation parameter of a refrigerated container, the method comprising the steps of
 determining a refrigeration effect caused by a refrigeration unit refrigerating the container,   calculating an actual rate of energy loss of the container due to heat ingress from the ambient surroundings,   determining an actual temperature difference between the interior of the container and the ambient air, and   determining the actual insulation parameter of the container from the ratio of said actual rate of energy loss and said actual temperature difference.   
     
     
         9 . The method according to  claim 8 , where the method of determining an actual insulation parameter is repeatedly performed over time and a current insulation parameter of the container is found from said determined actual insulation parameters of the container. 
     
     
         10 . (canceled) 
     
     
         11 . The method according to  claim 8 , further comprising the steps of:
 determining a difference in insulation parameter between the determined insulation parameter and a model insulation parameter for the container, and   updating the model insulation parameter for the container using the determined insulation parameter.   
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . The method according to  claim 8 , wherein the refrigeration effect released by the refrigeration unit is determined from a current rotational speed and a current intermittence time of a compressor of the refrigeration unit. 
     
     
         15 . The method according to  claim 8 , wherein the refrigeration effect released by the refrigeration unit is determined using at least one of the following parameters:
 a suction pressure at the inlet of the compressor, and   a discharge pressure from the compressor.   
     
     
         16 . The method according to  claim 8 , wherein a consumed power of evaporator fan or fans of an evaporator of the refrigeration unit is calculated and said consumed power is applied to calculating the actual rate of energy loss through the insulated outer walls of the container. 
     
     
         17 . The method according to  claim 16 , wherein a supply voltage and a supply frequency of the evaporator fan or fans are applied to calculating the consumed power of the evaporator fan or fans. 
     
     
         18 . The method according to  claim 8 , wherein the actual insulation parameter is determined when the container is operated in frozen mode at a temperature set point of the interior of the container of ≤−5° C. 
     
     
         19 . The method according to  claim 8 , wherein the actual insulation parameter is determined between defrost cycles of an evaporator of the refrigeration unit and is initiated when the temperature of the interior of the container has been determined to be stable after defrosting of the evaporator. 
     
     
         20 . The method according to  claim 8 , further comprising the step of identifying that the container needs maintenance based on the determined insulation parameter the model insulation parameter of the container. 
     
     
         21 . (canceled) 
     
     
         22 . (canceled) 
     
     
         23 . The method according to  claim 8 , further comprising the step of estimating the lifetime of a container based on the determined insulation parameter or the model insulation parameter of the container. 
     
     
         24 . A method of estimating a respiration rate of chilled, respiring commodities stored in a refrigerated container having insulated outer walls, the method comprising the steps of:
 determining an insulation parameter of the insulated outer walls of the container by means of the method according to  claim 8 ,   determining a refrigeration effect released by a refrigeration unit refrigerating the container,   determining an actual temperature difference between the interior the container and the ambient air,   calculating an actual rate of energy loss through the insulated outer walls of the container from said insulation parameter and said actual temperature difference, and   estimating the respiration rate from said determined refrigeration effect and the calculated actual rate of energy loss.   
     
     
         25 . The method according to  claim 24 , wherein said commodities comprise one or more of: fresh fruits, vegetables, bulbs, live plants and cut flowers. 
     
     
         26 - 29 . (canceled) 
     
     
         30 . The method according to  claim 24 , wherein the respiration rate is estimated when the container is operated at a temperature set point of the interior of the container in the range of −1° C., to 20° C. 
     
     
         31 . (canceled) 
     
     
         32 . (canceled)