Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D29/00—Arrangement or mounting of control or safety devices
  • F25D29/008—Alarm devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D29/00—Arrangement or mounting of control or safety devices
  • F25D29/003—Arrangement or mounting of control or safety devices for movable devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D2201/00—Insulation
  • F25D2201/10—Insulation with respect to heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
  • F25D2500/00—Problems to be solved
  • F25D2500/04—Calculation of parameters

Definitions

• Refrigerated containers require energy for operation in cooling and maintaining cooling temperatures. Over time the energy requirements may change due to the age of the container and different operating conditions.
• the present inventor has realised that the surveillance of an insulation parameter of refrigerated containers may provide a number of advantages in the use of the containers, such as to rate or rank a plurality of containers in dependence of their insulation condition, e.g. their ability to prevent the containers from warming up due to heat ingress.
• the inventor has found that such improvement may be achieved by surveiling the insulation condition each of a plurality of refrigerated containers, such as e.g. all refrigerated containers on a vessel, the refrigerated containers in a depot section for containers or all refrigerated containers on the fleet level of a company, the surveillance method comprising the step of repeadetly determinining an insulation parameter of each of the containers.
• a plurality of refrigerated containers such as e.g. all refrigerated containers on a vessel, the refrigerated containers in a depot section for containers or all refrigerated containers on the fleet level of a company
• Such surveillance of a larger group of refrigetared containers would provide detailed data about the status of the insulation condition of the containers as a group.
• the development in insulation parameter may be an indicator of general ageing and wear of the insulation, or a sudden drop in insulation of a container may indicate an injury to the container.
• the quality of repair and maintenance of the containers with respect to the insulation condition may also be detected by such surveillance.
• This further method may comprise the step of identifying which of the plurality of containers need maintenance based on the determined insulation parameter or the model insulation parameter of the container.
• the further method may also include the step of ranking the plurality of containers for suitable use thereof based on the determined insulation parameter or the model insulation parameter of the container.
• the further method may include the step of selecting the placement of each of said plurality of containers in a ship based on the determined insulation parameter or the model insulation parameter.
• the further method may also include the step of estimating the lifetime of each container based on the determined insulation parameter or the model insulation parameter of the container.
• the insulation parameter of each of the plurality of containers may be determined by means of the the set point temperature of that container, the ambient temperature of that container and an energy consumption of that container so than an energy balance in a steady state of the container can be determined, the energy consumption of the container being a measure of the refrigeration effect supplied to the container.
• the insulation parameter of each of the plurality of containers is determined by means of the method disclosed below as well as in the appended set of claims.
• the inventor has found that such improvement may in particular be achieved by determining an insulation parameter U of the refrigerated container according to the disclosed method determined on the basis of an energy balance equation.
• the heat ingress may be modelled by an insulation parameter U (W/K) and the temperature difference DT (K) between the inside and outside of the container or box.
• the amount of heat leaking from a container is dependent on multiple factors such as weather conditions, ambient temperatures, humidity, placement of the box on the ship, wind conditions etc.
• the refrigerated container may be a so-called reefer container, i.e. refrigerated containers having an integral refrigeration unit, in particular an intermodal container (shipping container) used in intermodal freight transport that is refrigerated for the transportation of temperature sensitive cargo.
• reefer container i.e. refrigerated containers having an integral refrigeration unit, in particular an intermodal container (shipping container) used in intermodal freight transport that is refrigerated for the transportation of temperature sensitive cargo.
• a method to determine an insulation parameter of a refrigerated container comprising at least the steps of determining a refrigeration effect caused by a refrigeration unit refrigerating the container
• the rate of energy loss is taken to be equal to the refrigeration effect Q Ref caused by a refrigeration unit refrigerating the container.
• the actual insulation parameter may be determined between defrost cycles of an evaporator of the refrigeration unit and be initiated when the temperature of the interior of the container has been determined to be stable after defrosting of the evaporator, so that the container and the commodities stored therein are at a constant temperature when the actual insulation parameter is determined, so that contribution to the energy balance due to changes in temperature over time of the container and the commodities is reduced or even for practical use can be considered to be eliminated.
• a more complete energy balance may include the contribution Qevaporator fans from the operation of evaporator fan or fans inside the container as well as the contribution Qintemai electrical consumed from the consumption of other internal electrical equipment in the container
• the latter contribution may often be of a minor quantity as compared to the magnitude of the other contributions, but is may be an advantage to calculate the consumed power of evaporator fan or fans of an evaporator of the refrigeration unit and apply said consumed power to calculating the actual rate of energy loss through the insulated outer walls of the container. This may in particular be calculated from applying the supply voltage and the supply frequency of the evaporator fan or fans to calculating the consumed power of the evaporator fan or fans provided that a look-up table, a formula or other means are provided to determine the consumption of electrical power from those input.
• the actual insulation parameter of the container is the parameter U act determined at a particular instance under a given set of operating conditions and may for that reason vary.
• the method of determining an actual insulation parameter (U act ) is repeatedly performed over time and a current insulation parameter (U CUr ) of the container is found from said determined actual insulation parameters (U act ) of the container.
• the current insulation parameter (U CUr ) of the container may be found by calculating a moving average value of said determined actual insulation parameters (U act ) of the container.
• the disclosed method may further comprise the steps of: determining a difference in insulation parameter between the determined insulation parameter, i.e. the actual or the current insulation parameter, and a model insulation parameter for the container, and
• the refrigerated container may be an intermodal container, the definition of which is currently generally determined by two ISO standards, ISO 668:2013 and ISO 1496- 1 :2013.
• the refrigerated container may receive cooling from a refrigeration unit situated external to the container itself, which e.g. delivers the cooling effect to the container by means of a circulating liquid such as brine or a refrigerant to be evaporated in the refrigerated container.
• the refrigerated container may alternatively comprise an integrated refrigeration unit for refrigeration of the container, such as in a so-called reefer container.
• the refrigeration effect Q Ref released by the refrigeration unit may be determined from the current rotational speed and the current intermittence time of a compressor of the refrigeration unit, provided that a look-up table, a formula or other means are provided to determine the refrigeration effect of the refrigeration unit from those input.
• the disclosed method may further comprise the step of identifying that the container needs to be maintained based on the determined insulation parameter (U ac t, Ucur) or the model insulation parameter (Umodei) of the container.
• the disclosed method may further include the step of ranking the container for suitable use thereof based on the determined insulation parameter (U ac t, Ucur) or the model insulation parameter (Umodei) of the container.
• the disclosed method may further include the step of determining of the placement of a container in a ship based on the determined insulation parameter (Uact, Ucur) or the model insulation parameter (Umodei).
• the disclosed method may further include the step of estimating the lifetime of a container based on the determined insulation parameter (U ac t, U CU r) or the model insulation parameter (Umodei) of the container.
• the present disclosure relates to 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 (U ac t, U CU r, Umodei) of the insulated outer walls of the container by means of the method disclosed herein to determine an insulation parameter of a refrigerated container,
• a number of chilled commodities such as fresh fruits, vegetables, bulbs, live plants and cut flowers, respires, i.e. convert starch to glucose or glucose to water, heat and CO 2 .
• the key to prolong shelf life of the chilled commodities is to lower their respiration rate, which is achieved by keeping the lowest possible temperature, typically between -1° C, to 20° C, depending on the commodity, and to control the atmosphere inside the refrigerated container, so as to maintain a low content of O 2 combined with the highest allowable content of CO 2 , the latter depending on the type of commodity in the container.
• Other components of the atmosphere may also be controlled, in particular the contents of ethylene.
• the current condition of the commodity is indicated and in case the conditions appear to be deviating from the optimal or requested conditions, action may be taken.
• the production of CO 2 can be found from the respiration heat and the level of the ventilation rate of the container can be adjusted accordingly in order to reach an allowable content of CO 2 in the atmosphere inside the container so that excessive ventilation of the container is avoided, which requires energy-consuming cooling and often drying of the external air, and so that excessive levels of CO 2 in the atmosphere inside the container are avoided which may lead to so-called CO 2 injuries in the commodities.
• the level of CO 2 found from determining the respiration heat may take the place of measurements by means of a CO 2 sensor in the storage compartment of the container, in which case the CO 2 sensor is superfluous, or may be used for obtaining a more reliable measure of the CO 2 level inside the storage compartment of the container.
• the volume of the produced CO 2 may be found from the ideal gas equation, y _ n*R*T
• the step of estimating the respiration rate may further comprise one or more of the steps of determining the consumed power of the evaporator fan or fans of an evaporator of a refrigeration unit of the container,
• the supply voltage and the supply frequency of the evaporator fan or fans may be applied to calculating the consumed power of the evaporator fan or fans as discussed previously
• the refrigeration effect released by the refrigeration unit may be determined from the current rotational speed and the current intermittence time of a compressor of the refrigeration unit as discussed previously.
• the refrigeration effect released by a refrigeration unit may be determined using at least one of the following parameters: the suction pressure at the inlet of the compressor, and
• the respiration rate is mostly estimated when the container is operated at a temperature set point of the interior of the container in the range of -G C, to 20° C, where most chilled commodities are contained, depending on the particular commodity.
• a refrigerated container having insulated outer walls and a data processing device comprising means for carrying out the method disclosed herein.
• a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method as described herein.
• Figure l is perspective cutaway view of a part of an insulated wall of a refrigerated container
• Figure 2 is a cross-section of a refrigerated container
• Figure 3 is a flow chart illustrating the process of determining the insulation parameter of the container and employing it for various purposes.
• the insulated wall 1 of a refrigerated container 2 may typically comprise the layers shown in Figure 1, where on the outside of the container 2 a corrugated steel sheet 3 provides the outermost layer. On the inside, an inner layer 4 is provided made from e.g. aluminium sheets or glass fibre reinforced polymer sheets. Optionally, a plywood layer 5 may be provided under the inner layer 4. Between the outer layer 3 and the inner layer 4, an insulating material 6 such as insulating foam of
• the temperature Tbox inside the container and Tamtnent are indicated.
• the commodities to be refrigerated are to be kept.
• the atmosphere in the storage space 8 is cooled by means of the evaporator 12 delivering the refrigeration effect Q Ref by evaporation of the liquid refrigerant received from the compressor 13.
• the evaporator fans 9 drive a flow of air from the storage space 8 of the container 2 and past the evaporator 12 in order to cool the air, which is returned to the storage space 8.
• the amount of water condensing at the evaporator 12 is determined by the condensation sensor 11.
• Air exchange between the surroundings of the container 2 and the storage space 8 inside the container for the purpose of controlling the content of the atmosphere inside the container in the storage space 8, in particular the CO2 contents, is controlled by means of the fresh air ventilators 10.
• a controller 14 is arranged to control the operation of the various parts of the equipment in the refrigerated container 2.
• the insulation parameter U of the standard refrigerated intermodal container is from the manufacturing of the new container known to have a value of 43 W-K ⁇ 1.
• the actual insulation parameter U act is determined in step 15. At such low temperatures, the stored commodities do not generate heat from respiration and the fresh air ventilators 10 are not operated.
• the actual insulation parameter U act is determined between defrost cycles at a time where the temperature T box inside the storage space 8 is stable.
• the refrigeration effect Q Ref of the evaporator 12 may be calculated from the mass flow of refrigerant multiplied by the difference between the specific enthalpy of the refrigerant before it reaches the evaporator and the specific enthalpy of the refrigerant after leaving the evaporator.
• the electric effect Qevaporator fans consumed by the evaporator fans 9 and the electrical effect Qintemai electrical consumed consumed by other minor equipment in the container 2 are determined in order to be able to determine the heat balance for the container and thereby the rate of heat inflow Qheatjngress into the container 2:
• the temperature difference can be determined
• the actual insulation parameter U act for the container can now be determined from the following:
• a model value of the insulation parameter for the container 2 is stored in the controller 14 of the container 2, starting with the factory standard of 43 W-K from new and may be updated when a current insulation parameter has been determined in step 17.
• the updated model insulation parameter may be employed to determine the best use of the container and to decide for repair (step 20) in case the insulation parameter Umodei exceeds a threshold value of e.g. 65 W-K or even scrapping of the container as discussed previously.
• the updated model insulation parameter Umodei may be used to rank the container for use, such as deep freezing of commodities for low values of Umodei or chilling of commodities at temperatures above 0° C for containers of higher values of Umodei, see step 22, or for determine the most suitable containers for particular placement in a ship in step 23.
• the expected lifetime of the container may be reevaluated, see step 21.
• an important use of the updated model insulation parameter Umodei for the container is to calculate a precise estimate of the respiration heat generated by chilled commodities stored in the refrigerated container, i.e. commodities such as fresh fruits, vegetables, bulbs, live plants and cut flowers, which are stored at temperatures where respiration takes place and heat, CO2 and water vapour are generated in accordance with the formulas provided above in step 19.
• the heat balance for the container is calculated with the purpose of determining the respiration heat rate Qrespiration and for that, the updated model insulation parameter Umodei for the container is used together with the temperature difference DT to determine the heat ingress Qheatjngress.
• Q Ref may be calculated from the mass flow of the refrigerant as discussed previously, alternatively it may be determined from data for the rotational speed of the compressor, the current intermittence time of the compressor, often combined with the suction pressure at the inlet of the compressor and/or the discharge pressure from the compressor.
• Qevaporator fans is the consumed power of the evaporator fans 9.
• Qintemai electrical consumed is consumed power of inside located electrical consumers for instance gas sensors, power electronics etc.
• Qheating elements is the consumed electrical power of heating elements placed inside the container.
• Qcondensation is found from the mass flow of water vapour condensated inside the container as determined by the condensation sensor 1 land the specific latent heat of water, i.e. the specific enthalpy of vaporization.
• Qheatjngress may be determined from the temperature difference DT and the model insulation parameter Umodei.
• Q respiration can then be found, which generally provides information about the present condition of the commodities, and more specifically can be used to determine the rate of generation of CO2 from the respiration as discussed previously, which may be employed in step 24 to control the ventilation rate of the interior storage space 8 of the container 2.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)

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• 2020
  • 2020-01-22 CN CN202080023006.4A patent/CN113614476B/zh active Active
  • 2020-01-22 US US17/423,664 patent/US20220082323A1/en active Pending
  • 2020-01-22 WO PCT/EP2020/051474 patent/WO2020152203A1/en unknown
  • 2020-01-22 EP EP20701594.2A patent/EP3914867A1/en active Pending

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