SE544291C2

SE544291C2 - A method for testing performance of a climate-controlled freight container and such freight container

Info

Publication number: SE544291C2
Application number: SE2051166A
Authority: SE
Inventors: Anders Herolf; Fredrik Grevfors
Original assignee: Envirotainer Eng Ab
Priority date: 2020-10-02
Filing date: 2020-10-02
Publication date: 2022-03-29
Also published as: WO2022071856A1; WO2022071856A8; SE2051166A1

Abstract

A method for testing performance of a climate-controlled freight container comprises cooling down (S10) of a cargo compartment of the freight container to a predefined target temperature by use of a cooling system, comprising at least two cooling modules. A temperature distribution within the cargo compartment is equalized (S20) during a predetermined equalizing period. An individual cooling module test (S30) is performed for all the at least two cooling modules, one at a time. The individual cooling module test in turn comprises controlling (S32) of the cargo compartment to have a constant temperature during a predetermined period by operating a single cooling module and measuring (S34) a power consumption of the single cooling module during the predetermined period.

Description

lO AMENDED DESCRIPTIONANNOTATED VERSION Å METHÜÜ FÜR TESTÉNQ FERFÜRMÅNQE GF Å QLEWÃÅTE»ÜÜNTRÜLLEB FREÉGET ÜÜNTÅÉÉWTER àšïïë SUQX-š FREIGHT CONTAINER TECHNICAL FIELD The present invention relates in general to freight containers and in particularto methods and devices for performance tests of climate-controlled freight containers.

BACKGROUND Today, transportation of goods Worldwide is a huge business, having impacton the daily life of substantially all people around the World. Many productsare produced far from the location Where they are assumed to be consumedor used, and transportation is therefore crucial. Many products today aresensitive for storage/ transportation times, the environment, and physical exposure of e.g. vibrations or shocks.

Climate-controlled air-freight containers are available since many years. Thecommon basic idea is to produce a climate-controlled ﬂoW of air, or other gas,that is entered into the cargo compartment. The cooling action mayfurthermore be controlled based on different sensor measurements, usually ofthe temperatures Within the systems. For long time, the refrigeration Wasrelying on passive cooling by dry ice, but in recent years, battery-powered refrigeration equipment has become Widely used for active cooling.

If a trustable transport of sensitive goods should be performed, there are a lotof different systems that have to Work properly. The climate-control units haveto operate according to expected performance, the power system has to becharged to a suitable level, the container thermal isolation has to be intact,the distribution of climate-controlled air has to be operable, etc. Ideally, everypart or module in a climate-controlled freight container should be controlled before a shipping is initiated, in terms of operability. This could be performed lO AMENDED DESCRIPTIONANNOTATED VERSION by making tests of every part, either as mounted in the container or de-mounted therefrom. However, such procedures are far too time consuming for being realistic.

SUMMARY A general object is to provide efficient and reliable methods and devices for performance checks of climate-controlled freight containers.

The above object is achieved by methods and devices according to the independent claims. Preferred embodiments are defined in dependent claims.

In general words, in a first aspect, a method for testing performance of aclimate-controlled freight container comprises cooling down of a cargocompartment of the freight container to a predefined target temperature byuse of a cooling system. The cooling system comprises at least two coolingmodules. A temperature distribution within the cargo compartment isequalized during a predetermined equalizing period. An individual coolingmodule test is performed for all the at least two cooling modules, one at a time.The individual cooling module test in turn comprises controlling of the cargocompartment to have a constant temperature during a predetermined periodby operating a single cooling module and measuring a power consumption of the single cooling module during the predetermined period.

In a second aspect, a climate-controlled freight container comprises a cargocompartment, a cooling system and a control unit. The cooling system has atleast two cooling modules and an air distribution arrangement. The airdistribution arrangement is configured to distribute air from the coolingmodules around and/ or into the cargo compartment and back. The controlunit is configured to control an operation of the cooling system. The controlunit is configured to instruct the cooling system to cool down the cargocompartment of the freight container to a predefined target temperature. The control unit is further configured to instruct the cooling system to equalize a lO AMENDED DESCRIPTIONANNOTATED VERSION temperature distribution within the cargo compartment during apredetermined equalizing period. The control unit is further configured toinstruct the cooling system to perform an individual cooling module test forall the at least two cooling modules, one at a time. Thereby, as being comprisedin the individual cooling module test, the control unit is further configured toinstruct the cooling system to operate a single cooling module to control thecargo compartment to have a constant temperature during a predeterminedperiod. The climate-controlled freight container further comprises a powermeter, configured to measure a power consumption of the single cooling module during the predetermined period.

One advantage with the proposed technology is an efficient and reliable checkof climate-controlled freight containers is provided. Other advantages will be appreciated when reading the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The invention, together with further objects and advantages thereof, may bestbe understood by making reference to the following description taken togetherwith the accompanying drawings, in which: FIG. 1 illustrates schematically a cross-sectional view of an embodimentof a freight container; FIG. 2 illustrates a diagram of temperature measurements during anembodiment of a test program; FIG. 3 illustrates a diagram illustrating an example of a powerconsumption for the cooling modules during an embodiment of the individualcooling module tests; FIG. 4 is a ﬂow diagram of steps of an embodiment of a method fortesting performance of a climate-controlled freight container; FIG. 5 is a ﬂow diagram of steps of an embodiment of step S10 of Fig. 4; FIG. 6 is a ﬂow diagram of steps of an embodiment of step S20 of Fig. 4;and FIG. 7 is a ﬂow diagram of steps of an embodiment of step S40 of Fig. 4.

AMENDED DESCRIPTIONANNOTATED VERSION DETAILED DESCRIPTION Throughout the drawings, the same reference numbers are used for similar or corresponding elements.

In the following, embodiments of air-freight containers are described.However, even though the present ideas are of most benefit for air freight, thesame approaches are also operational for other types of freight containers.Thus, in one preferred embodiment, the freight container is an air-freight container.

For a better understanding of the proposed technology, it may be useful tobegin with a discussion of features that are important to consider duringtesting. First, it can be concluded that the different units and modules haveto operate correctly, as they are. Moreover, they also have to operate correctlytogether, and together with the freight container structure. Most ideally, theyalso should operate correctly in the interaction with the goods to betransported. However, since there typically is no time or possibility availableto make performance tests when the goods have been loaded into thecontainer, tests have to be performed on either empty containers or containers having a dummy load.

This insight has led to the development of a testing scheme for performanceof a climate-controlled freight container that comprises at least three phases,and preferably at least four phases. Such a testing scheme will be presentedfurther below. However, in order to have a better idea of how the actual freightcontainer may look like, we will start to brieﬂy present a climate-controlled freight container on which the testing scheme is intended to be operable.

Figure 1 illustrates an embodiment of a climate-controlled ﬂight container 10in a cross-sectional view. The climate-controlled ﬂight container 10 is defined by a casing 12. The casing 12 encloses a cargo compartment 20 and a control AMENDED DESCRIPTIONANNOTATED VERSION compartment 26. The casing 12 comprises a ﬂoor 16, a ceiling 14 and Walls18. The cargo compartment 20 and a control compartment 26 are separated by a partition Wall 28.

The climate-controlled ﬂight container 10 also comprises a Cooling system 30.The cooling system 30 has in the present embodiment three cooling modules40, of Which one is visible in the figure. However, in other embodiments, thenumber of cooling modules 40 can be different, but at least two. This gives ahigher maximum cooling effect and provides a redundancy if one of the coolingmodules 40 fails. The cooling system 30 further comprises an air distributionarrangement 21, Which is configured to distribute air from the cooling modulesaround and/ or into the cargo compartment and back. The cooling system 30is thereby configured for controlling a temperature of the cargo compartment20 by providing a ﬂoW 100 of temperature-controlled air around and/ or intothe cargo compartment 20 by means of the air distribution arrangement 21.The air distribution arrangement 21 is in this embodiment constituted by theinner parts of the casing and some deliberately provided ﬂoW-directingcomponents. The ﬂoW 100 of temperature-controlled air is in this embodiment provided in vicinity of the ceiling 14 of the cargo compartment 20.

In this particular embodiment, the distribution of the ﬂoW 100 of temperature-controlled air is supported by an upper gas-ﬂoW distributer plate 22. The ﬂoW100 of temperature-controlled air is here directed to the space between theceiling 14 and the upper gas-ﬂoW distributer plate 22. The upper gas-ﬂoWdistributer plate 22 does not cover all the distance to the Walls and leavesopenings for climate-conditioned gas to ﬂoW 108 into the main cargocompartment. Likewise, there is in this particular embodiment also a side gas-ﬂow collector plate 24, placed With a small distance to the partition Wall 28separating the cargo compartment 20 from the control compartment 26. Gasleaving the cargo compartment 20 ﬂoWs beneath the edge of the side gas-ﬂoWcollector plate 24 and upWards along the partition Wall 28 as a return air-ﬂoW 104.

AMENDED DESCRIPTIONANNOTATED VERSION The Control Compartment 26 has a Cooling module support with threemounting positions, one for each Cooling module 40. Three Cooling modules40 are mounted in the Cooling module support. EaCh Cooling modules 40 inoperation reCeives air through an input port 42 and provides an air-ﬂow 102 going out from the Climate module 40 through an output port 44.

The Cooling system 30 Comprises or is assoCiated with a surveillanCe systemComprising at least one internal temperature sensor 53A-C arranged formeasuring a temperature inside the Cargo Compartment 20 and/ or in an air- ﬂow to 104 and/ or from 102 the Cargo Compartment.

In the present embodiment, first internal temperature sensors are plaCed atdifferent loCations in the Cargo Compartment and may therefore be denotatedas Cargo Compartment temperature sensors 53A. In the present embodiment,two Cargo Compartment temperature sensors 53A are plaCed at the side wall18, two Cargo Compartment temperature sensors 53A are plaCed at the sidegas-ﬂow ColleCtor plate 24 and one Cargo Compartment temperature sensor53A is plaCed at an edge of the upper gas-ﬂow distributer plate 22. A seCondinternal temperature sensor 53B is plaCed in the gas-ﬂow 102 going out fromthe Climate Control system 30. A third internal temperature sensor 53C isplaCed in the gas-ﬂow 104 going into the Cooling system 30. In otherembodiments, other Combinations of internal temperature sensors may beprovided. A Control unit 50 is Configured to Control an operation of the Cooling system 30.

In order to have a thorough Control of the Cooling operation and the generalfunCtion of the freight Container, a test program is performed. The test program has at least three stages and preferably at least four stages.

A first stage is a pull-down stage. This stage Comprises Cooling down of theCargo Compartment of the freight Container to a predef1ned target temperature by use of a Cooling system. This stage preferably starts with the temperature lO AMENDED DESCRIPTIONANNOTATED VERSION of the cargo compartment being essentially equal to an ambient temperature.Preferably, all cooling modules are operated simultaneously and with a settingfor achieving a maximum cooling effect. The pull-down is temperaturecontrolled and the internal temperature sensors are used for achieving thetemperature information during this stage. Preferably, a set temperature forthe cooling modules is set a couple of degrees lower than the targettemperature. The set temperature should be low enough to trig a maximum cooling.

A typical example of temperature measurements during a test program isillustrated in Figure 2. The cool-down stage 201 is illustrated as the first partof the test program. In this particular example, the test program is run on afreight container having 8 internal temperature sensors within the cargocompartment and two additional temperatures sensors for measuring anexternal or ambient temperature. The curves 211-218 illustrate the differentreadings of the individual internal temperature sensors, whereas curves 219-220 indicates the time evolution of the measurements of the two externaltemperature sensors. The cool-down stage starts at time tO and at time t1, thetarget temperature, which in this particular case was set to 5.3°C, was reached.

Preferably, the pull-down process is monitored, as in the above discussedfigure. A cooling-down time is then measured. The cooling-down time is simplydefined as the time from a start of the cooling system until the predefinedtarget temperature is reached. In the example of Figure 2, the cooling-downtime is determined to be tcd = t1 - tO. This cooling-down time gives a first indication of the condition of the freight container.

In a preferred embodiment, the cooling-down stage further comprisesindicating of a general operation error warning as a response to a cooling-down time exceeding a predetermined limit value. The cooling-down time may give a first hint about if there are any operational errors of the cooling modules lO AMENDED DESCRIPTIONANNOTATED VERSION and/ or if there are any major thermal isolation problems in the freight container.

In a preferred embodiment, a temperature outside the cargo compartment isalso measured. This measure can be an estimate of the original cargocompartment temperature and an estimate of the prevailing ambienttemperature. Since the cooling-down time at least to a part depends on theoriginal cargo compartment temperature as Well as on the prevailing ambienttemperature, the predetermined limit value associated With the cool-downstage for indicating a general operation error Warning is determined independence of the measured outside temperature. HoWever, the detailedreasons for the possible error may be difficult to conclude, since a long cool- down time may depend on several independent factors.

A second stage of the test program is an equalization stage. This stage startsat tO When the pull-down stage is ended or soon after, as illustrated by thereference number 202 in Figure 2. A first reason for running the equalizationstage is to provide a freight container With an as uniform temperaturedistribution as possible, as a preparation for later stages. A second reason forthe equalization stage is that it offers possibilities to detect any errors in theair distribution system or local defects in the thermal isolation of the freight container.

In the example illustrated in Figure 2, the equalization stage is performed Withonly one active cooling module. This insures that the cooling action Will beessentially uniform during the equalization stage, removing any possibledifferences between different cooling modules. The temperatures Within thecontainer cargo compartment Will stabilize, but since there are some materialWithin the cargo compartment that has to gain the same temperature, thisprocess may take some time. HoWever, eventually, a temperature equilibriumhas been established at time t2. In the present example, the target temperature around Which this stabilization takes place Was selected to 5°C. lO AMENDED DESCRIPTIONANNOTATED VERSION As mentioned above, the results of the equalization stage may also preferablybe used for diagnosing purposes. In a preferred embodiment the equalizing ofa temperature distribution Within the cargo compartment in turn comprisesmonitoring temperatures Within the cargo compartment during thepredetermined equalizing period. The temperatures are measured at at leasttWo different locations Within the cargo compartment. More preferably, moretemperature sensors are used. In the present example of Figure 2, eight different sensors measuring the internal temperature are used.

In Figure 2, it can be seen that there are some differences in readings betweenthe different temperature sensors, i.e. between the curves 211-218. If thesedifferences are small, as is the case in the diagram of Figure 2, this indicatesa homogeneous distribution of the cooled air Within the cargo compartment.A seen in Figure 2, all temperatures are typically Within 1-2°C from each other,Which has to be considered as an admitted variation. From Figure 2, it canalso be seen that the temperatures vary more in the beginning of the equalizingstage but become stable after a certain time. This initial transient course iscaused by the cooling of the interior parts of the cargo compartment. If thetests are preformed With cargo in the cargo compartment, this transient time Will be much longer.

Indications of possible errors in the freight container functions may be foundin different Way. If there is some malfunctioning part in the air distributionsystem, e.g. blocked channels, non-efficient fans or missing distributor orcollection plates, an even distribution of the temperature Within the cargocompartment may very Well be obtained, but the time until this equilibriumstate is reached may take longer time than expected for a Well operatingsystem. Also, if the thermal isolation of the freight container is not intact, e.g.if there exist local defects in the isolation material or if the door is not properlysealed When being shut. Vacuum isolated panels (VIP) are today often used forthermal isolation purposes and unfortunately it is not uncommon that suchpanels are damaged during transport handling of the freight container. A punctured Wall Will lose a significant part of its isolating properties. Such local lO AMENDED DESCRIPTIONANNOTATED VERSION defects in the thermal isolation Will probably result in an equilibrium conditionwhere different parts of the cargo compartment present somewhat differing temperatures.

Therefore, in one embodiment, the monitoring of the temperatures furthercomprises determination of a highest temperature difference betweentemperatures at the at least two locations at an end of the predeterminedequalizing period. If this difference is large, this may indicate that there are some local isolation problems.

In another alternative or complementing embodiment, the monitoring furthercomprises determining of a duration of a transient time until the temperaturesat the at least two locations reaches a steady-state temperature. The transienttime thus indicates the time when the cargo compartment still is not in anequilibrium state, but where changes in temperatures still are occurring. Long transient times may indicate some problems in the air distribution system.

Preferably, for both embodiments above, they are followed by a possible errorindication, if deviations from the normal behavior is detected. In other words,the monitoring further comprises indication of a suspected air distributionfailure and/or local isolation damage as a response to that the highesttemperature difference exceeds a predetermined value and/ or the transient time exceeds a predetermined time limit.

When the cargo compartment of the freight container has reached theequilibrium state at the end of the equalization stage at t2, the third stage isstarted. In this third, individual module test stage 203, an individual coolingmodule test is performed for all cooling modules, one at a time. By makingthese tests sequentially, the operation of each individual cooling module canbe distinguished. A difference in performance between the different individual cooling modules can thereby be detected. lO 11 AMENDED DESCRIPTIONANNOTATED VERSION In a preferred embodiment, the performance test Will be based on energyconsumption that is necessary for the cooling modules to maintain a constanttemperature. The individual cooling module test thus in turn comprisescontrolling of the cargo compartment to have a constant temperature duringa predetermined period by operating a single cooling module. A powerconsumption of the single cooling module is measured during this predetermined period.

In the particular tests illustrated in Figure 2, the predetermined time for eachcooling module to operate on its own was set to 30 minutes. However, other durations can also be used.

The monitoring of the power consumption is preferably also followed up. Tothis end, in a preferred embodiment, the individual cooling module test furthercomprises evaluation of a variance in power consumption for each individual cooling module, as illustrated by the short, dotted lines.

This evaluation may be performed in different ways. One possibility is tocalculate a total power consumption for each individual cooling module, aswell as an average power consumption for all cooling modules. If the differentcooling modules all are operating according to the expectations, all individualcooling modules should have essentially the same power consumption and therefore also the same power consumption as the average over all modules.

In one embodiment, the individual cooling module test further comprisesindicating of a suspected cooling module failure in a first cooling module as aresponse to that the variance in power consumption of the first cooling moduleeXceeds a predetermined value and/ or that the total power consumption forthe first cooling module differs from the average power consumption by more than a predetermined fraction.

By such a procedure, it may be possible to detect the eXistence and identity of a malfunctioning cooling device. The modular design of the cooling system lO 12 AMENDED DESCRIPTIONANNOTATED VERSION then makes it easy to simply exchange this failing Cooling module for a well- operating one before an actual shipping is made.

It is an advantage that the individual cooling module test is planned to takeplace in the test program just after the equalization stage, since the individual cooling module tests then are initiated from well-defined conditions.

In Figure 2, the temperature readings during the individual module test stageare constant, which is a first proof of that all cooling modules are operatingwell enough to meet the requirements of keeping the temperatures constant.However, it is the power consumption readings that will reveal any minorproblems. Figure 3 illustrates such power consumption 221-223 for thecooling modules during the individual cooling module tests. As can be seen,all cooling modules have essentially the same power consumption, indicatingthat they all are operating in a same way, and then also probably in the expected manner.

Returning back to Figure 2, there is also a fourth stage 204; a pull-up stage.This stage is not absolutely necessary to perform, but since no additionalcooling operations or additional hardware is needed, it is preferred to also include this fourth stage into the test program.

The pull-up stage is basically a passive test of the isolation performance insidethe container. At time t3, the cooling action of the cooling modules is shutdown, however, the fans for distributing air into the container, which typicallyare situated in the cooling modules, are operated at a medium rate, sufficientto maintain the equalized temperature distribution within the cargocompartment. The container will passively warm up due to the heatconduction through the walls. This passive warming-up of the cargocompartment is then monitored, by following the temperature readings from the internal temperature sensors. lO 13 AMENDED DESCRIPTIONANNOTATED VERSION As seen in Figure 2, the Warming up process starts With a rapid increase,Which successively Will be slower and eventually the temperature inside thecargo compartment Will reach the ambient temperature. The rate With Whichthe temperature increases gives information about the total thermal isolationof the freight container. Any damaged VIP or any leaking door etc., Willcontribute to the temperature increase. In particular, the initial Warming-uprate Will be strongly inﬂuenced by any isolation fault. Typically, the first 1-2 hours are the most important to monitor.

In one embodiment, the monitoring further comprises indication of asuspected cargo compartment isolation failure as a response to an initial Warming-up rate exceeding a predetermined limit value.

As in the case of the pull-down stage, the temperature rise in the pull-up stageWill be dependent on the ambient temperature, at least to certain degree.Therefore, in a preferred embodiment, the monitoring further comprisesmeasuring of a temperature outside the cargo compartment. Thepredetermined limit value is then determined in dependence of the measured temperature.

Besides the test scheme stages described here above, additional stages can beadded. It is, however, important that the performing of the individual coolingmodule tests starts from a Well-characterized temperature distribution Within the cargo compartment.

The performance test described above could be performed by manuallyinitiated operations. HoWever, since all procedures are easily performed in anautomated Way, the performance test could easily be provided as a pre-programmed test procedure. Since the total test takes some time to perform, the automated tests could by advantage be performed during the night.

Figure 4 is a ﬂoW diagram of steps of an embodiment of a method for testing performance of a climate-controlled freight container. In step S10, a cargo 14 AMENDED DESCRIPTIONANNOTATED VERSION Compartment of the freight Container is Cooled down to a predef1ned targettemperature by use of a Cooling system. The Cooling system Comprises at least two Cooling modules.

In one preferred embodiment, as illustrated in Figure 5, the step S10 of Coolingdown a Cargo Compartment in turn Comprises the step S12, in whiCh a Cooling-down time from a start of the Cooling system until the predef1ned targettemperature is reaChed is measured. In a further preferred embodiment, instep S16, a general operation error warning is indiCated as a response to a Cooling-down time eXCeeding a limit value.

In one further preferred embodiment, the step S10 of Cooling down a CargoCompartment further also Comprises the step S14, in whiCh a temperatureoutside the Cargo Compartment is measured. By doing this, the limit value of step S16 Can be determined in dependenCe of this measured temperature.

Returning to Figure 4, in step S20, a temperature distribution within the Cargo Compartment is equalized during a predetermined equalizing period.

In one preferred embodiment, as illustrated in Figure 6, the step S20 ofequalizing a temperature distribution within the Cargo Compartment in turnComprises the step S22, in whiCh temperatures at at least two loCations withinthe Cargo Compartment are measured during the predetermined equalizingperiod. Prefer ably, in step S24. a highest temperature differenCe betweentemperatures at the at least two loCations at an end of the predeterminedequalizing period is determined. Preferably, in step S26, a duration of atransient time until the temperatures at the at least two loCations reaChe asteady-state temperature is determined. Preferably, in step S28, a suspeCtedair distribution failure is indiCating as a response to the results of at least oneof steps S24 and S26. One of the Criteria, based on the results of step S24 isthat the highest temperature differenCe eXCeeds a predetermined value. Theother Criteria, based on step S26, is that the transient time eXCeeds a predetermined time limit. lO AMENDED DESCRIPTIONANNOTATED VERSION Returning to Figure 4, in step S30, an individual Cooling module test for allthe at least two Cooling modules are performed, one at a time. The individualCooling module test in turn Comprises step S32, in whiCh the CargoCompartment is Controlled to have a Constant temperature during apredetermined period by operating a single Cooling module. The individualCooling module test also Comprises step S34, in whiCh a power Consumption of the single Cooling module is measured during the predetermined period.

In one preferred embodiment, individual Cooling module test S30 furtherComprises step S36, in whiCh a varianCe in power Consumption is evaluatedfor eaCh individual Cooling module. In one preferred embodiment, individualCooling module test S30 further Comprises step S37, in whiCh a total powerConsumption for eaCh individual Cooling module is CalCulated, as well as anaverage power Consumption for all Cooling modules. Preferably, the individualCooling module test S30 further Comprises step S38, in whiCh a suspeCtedCooling module failure in a first Cooling module is indiCatied as a response toat least one of two Criteria. A first Criteria, based on the results of step S36, isthat the varianCe in power Consumption of the first Cooling module eXCeeds apredetermined value. The other Criteria, based on the results of step S37, isthat the total power Consumption for the first Cooling module differs from the average power Consumption by more than a predetermined fraCtion.

In a preferred embodiment, the method for testing performanCe of a Climate-Controlled freight Container Comprises the further step S40, in whiCh a passive warming-up of the Cargo Compartment is monitored.

In a further preferred embodiment, as illustrated in Figure 7, the step S40 ofmonitoring Comprises the further step S44, in whiCh a suspeCted CargoCompartment isolation failure is indiCated as a response to an initial warming-up rate eXCeeding a limit value. Preferably, in step S42, a temperature outsidethe Cargo Compartment is measured. Thereby, the limit value in step S44 may be determined in dependenCe of that measured temperature. lO 16 AMENDED DESCRIPTIONANNOTATED VERSION As for the physical implementation allowing the test schedule to be performed,preferably autonomously, Figure 1 is again referenced. As was mentionedabove, a control unit 50 is conf1gured to control an operation of the coolingsystem 30. This control unit 50 can also be utilized for managing the test schedule.

To this end, the control unit 50 is conf1gured to instruct the cooling system 30to cool down the cargo compartment 20 of the freight container 10 to apredef1ned target temperature. The control unit 50 is further conf1gured toinstruct the cooling system 30 to equalize a temperature distribution withinthe cargo compartment during a predetermined equalizing period. The controlunit 50 is further conf1gured to instruct the cooling system 30 to perform anindividual cooling module test for all the at least two cooling modules, one ata time. The control unit 50 being further configured, as comprised in theindividual cooling module test, to instruct the cooling system 30 to operate asingle cooling module to controlling the cargo compartment to have a constanttemperature during a predetermined period. The freight container 10 furthercomprises a power meter 80. The power meter is conf1gured to measure apower consumption of the single cooling module during the predeterminedperiod. This can be achieved by having one power meter 80 per coolingmodule, measuring the power consumption of just that cooling module.However, it is also feasible to have one power meter 80 measuring the totalpower consumption of all cooling modules. Since the cooling modules areoperated sequentially, the power consumption of each individual coolingmodule can be distinguished. The power meter 80 is communicationally connected to the control unit 50.

Preferably, the control unit 50 is further conf1gured to evaluate a variance inpower consumption for each individual cooling module measured by the powermeter. Preferably, the control unit 50 is further conf1gured to calculate a totalpower consumption for each individual cooling module, as well as an average power consumption for all cooling modules. Preferably, the control unit 50 is 17 AMENDED DESCRIPTIONANNOTATED VERSION further Configured to indiCate a suspeCted Cooling module failure in a firstCooling module as a response to that the varianCe in power Consumption ofthe first Cooling module eXCeeds a predetermined value and/ or that the totalpower Consumption for the first Cooling module differs from the average power Consumption by more than a predetermined fraCtion.

In one preferred embodiment, the Control unit 50 is further Configured tomonitoring a passive warming-up of the Cargo Compartment 20. Preferably,the Control unit 50 is further Configured to indiCate, during or after themonitoring, a suspeCted Cargo Compartment isolation failure as a response to an initial warming-up rate eXCeeding a limit value.

In a preferred embodiment, the freight Container 10 further Comprises atemperature meter 82, Configured for measuring a temperature outside theCargo Compartment 20. In this embodiment, the temperature meter 82 isloCated within the Control Compartment 26, whiCh is believed to follow theambient temperature relatively Close. Alternatively or as a Complement, atemperature meter 82 may also be provided outside the Casing 12. Preferably,suCh outside temperature meters are reCessed into the outer surfaCe of thefreight Container 10 in order to avoid transport damages. The temperaturemeter 82 is CommuniCationally ConneCted to the Control unit 50. Thereby, theControl unit 50 may determine the limit value used for evaluating thewarming-up rate in dependenCe of the measured temperature outside the Cargo Compartment 20.

As was desCribed above, first internal temperature sensors 53A are plaCed atdifferent loCations in the Cargo Compartment 20. At least two suCh CargoCompartment temperature sensors 53A are provided. Thereby, temperaturesat at least two loCations within the Cargo Compartment Can be measuredduring the predetermined equalizing period. The Cargo Compartmenttemperature sensors 53A are CommuniCationally ConneCted to the Control unit50. Therefore, preferably, the Control unit 50 is further Configured to determine a highest temperature differenCe between temperatures at the at lO 18 AMENDED DESCRIPTIONANNOTATED VERSION least two locations at an end of the predetermined equalizing period.Preferably, the control unit 50 is further configured to determine a durationof a transient time until the temperatures at the at least two locations reachesa steady-state temperature. Preferably, the control unit 50 is furtherconfigured to indicate a suspected air distribution failure as a response to thatthe highest temperature difference eXceeds a predetermined value and/ or that the transient time exceeds a predetermined time limit.

In one preferred embodiment, the control unit 50 is further configured tomeasure a cooling-down time from a start of the cooling system until thepredef1ned target temperature is reached. Preferably, the control unit 50 isfurther configured to indicate a general operation error warning as a responseto a cooling-down time eXceeding a limit value. If the freight container 10 hasa temperature meter 82 configured for measuring a temperature outside thecargo compartment, this limit value may be determined in dependence of the measured temperature outside the cargo compartment.

In one aspect of the present technology, it is also possible to use the pull-upstage as a main performance test. This pull-up stage has by necessity to followa pull-down stage, with or without any failure analysis. Preferably, also anequalizing stage precedes the pull-up stage in order to ensure a homogeneous temperature distribution within the cargo compartment.

In other words, one embodiment of a method for testing performance of aclimate-controlled freight container comprises the steps of cooling down acargo compartment of the freight container to a predef1ned target temperatureby use of a cooling system and- monitoring a passive warming-up of the cargocompartment. Preferably, the method additionally comprises the step ofindicating a suspected cargo compartment isolation failure as a response toan initial warming-up rate eXceeding a first limit value. Also preferably, thestep of monitoring further comprises measuring of a temperature outside thecargo compartment, whereby the first limit value is determined in dependence of the measured temperature. lO 19 AMENDED DESCRIPTIONANNOTATED VERSION Analogously, an embodiment of a Climate-Controlled freight ContainerComprises a Cargo Compartment, a Cooling system and a Control unit. TheCooling system has at least one Cooling module and an air distributionarrangement, Configured to distribute air from the Cooling module(s) aroundand/ or into the Cargo Compartment and back. The Control unit is Conﬁguredto Control an operation of the Cooling system. The Control unit is Conf1gured toinstruCt the Cooling system to Cool down the Cargo Compartment of the freightContainer to a predef1ned target temperature. The Control unit is furtherConﬁgured to monitoring a passive warming-up of the Cargo Compartment.Preferably, the Control unit is further Configured to, during or after themonitoring, indiCate a suspeCted Cargo Compartment isolation failure as aresponse to an initial warming-up rate eXCeeding a first limit value. Alsopreferably, the Climate-Controlled freight Container further Comprises atemperature meter, Configured for measuring a temperature outside the CargoCompartment. The first limit value Can then be determined in dependenCe of the measured temperature.

The embodiments desCribed above are to be understood as a few illustrativeexamples of the present invention. It will be understood by those skilled in theart that various modif1Cations, Combinations and Changes may be made to theembodiments without departing from the sCope of the present invention. InpartiCular, different part solutions in the different embodiments Can beCombined in other Configurations, where teChniCally possible. The sCope of the present invention is, however, defined by the appended Claims.

Claims

ANNOTATED VERSION AMENDED CLAIMS

1. A method for testing performance of a climate-controlled freightcontainer (10), comprising the step of: - cooling down (S10) a cargo compartment (20) of said freight container(10) to a predef1ned target temperature by use of a cooling system (30),characterized in that said cooling system (30) comprisggs-fá-cz-z-g; at least two cooling modules(40); and by the further steps of: - equalizing (S20) a temperature distribution within said cargocompartment (20) during a predetermined equalizing period; and - performing an individual cooling module test (S30) for all said at leasttwo cooling modules (40), one at a time; said individual cooling module test (S30) in turn comprising: - controlling (S32) said cargo compartment (20) to have a constanttemperature during a predetermined period by operating a single coolingmodule (40); - measuring (S34) a power consumption of said single cooling module (40) during said predetermined period.

2. The method according to claim 1, characterized in that saidindividual cooling module test (S30) further comprises:- evaluating (S36) a variance in power consumption for each individual cooling module (40).

3. The method according to claim 1 or 2, characterized in that saidindividual cooling module test (S30) further comprises: - calculating (S37) a total power consumption for each individualcooling module (40), as well as an average total power consumption for all cooling modules (40).

4. The method according to claim 2 or 3, characterized in that said individual cooling module test (S30) further comprises: AMENDED CLAIMSANNOTATED VERSION - indiCating (S38) a suspeCted Cooling module failure in a first Coolingmodule (40) as a response to at least one of:said varianCe in power Consumption of said first Cooling module(40) eXCeeds a predetermined value; andif being dependent on Claim 3, said total power Consumption forsaid first Cooling module (40) differs from said average power Consumption by more than a predetermined fraCtion.

5. The method aCCording to any of the Claims 1 to 4, characterized byfurther Comprising the step of:- monitoring (S40) a passive warming-up of said Cargo Compartment (20).

6. The method aCCording to Claim 5, characterized in that said step ofmonitoring (S40) further Comprises:- indiCating (S44) a suspeCted Cargo Compartment isolation failure as a response to an initial warming-up rate eXCeeding a first limit value.

7. The method aCCording to Claim 6, characterized in that said step ofmonitoring (S40) further Comprises:- measuring (S42) a temperature outside said Cargo Compartment (20),whereby said first limit value is determined in dependenCe of said measured temperature.

8. The method aCCording to any of the Claims 1 to 7, characterized inthat said step of equalizing (S20) a temperature distribution within said CargoCompartment (20) in turn Comprises the step of: - monitoring (S22) temperatures at at least two loCations within said Cargo Compartment (20) during said predetermined equalizing period.

9. The method aCCording to Claim 8, characterized in that said step of monitoring (S22) further Comprises: 22 AMENDED CLAIMSANNOTATED VERSION - determining (S24) a highest temperature difference betweentemperatures at said at least two locations at an end of said predetermined equalizing period.

10. The method according to claim 8 or 9, characterized in that said stepof monitoring (S22) further comprises: - determining (S26) a duration of a transient time until saidtemperatures at said at least two locations reaches a steady-state temperature.

11. The method according to claim 9 or 10, characterized in that saidstep of monitoring (S22) further comprises:- indicating (S28) a suspected air distribution failure as a response toat least one of:said highest temperature difference exceeds a predeterminedvalue; andif being dependent on claim 10, said transient time exceeds a predetermined time limit.

12. The method according to any of the claims 1 to 11, characterized inthat said step of cooling down (S10) a cargo compartment (20) in turncomprises the step of: - measuring (S12) a cooling-down time from a start of said cooling system until said predef1ned target temperature is reached.

13. The method according to claim 12, characterized in that said step ofcooling down (S10) a cargo compartment (20) comprises:- indicating (S16) a general operation error warning as a response to a cooling-down time eXceeding a second limit value.

14. The method according to claim 13, characterized in that said step ofcooling down (S10) a cargo compartment (20) further comprises: - measuring (S14) a temperature outside said cargo compartment; AMENDED CLAIMSANNOTATED VERSION whereby said second limit value is determined in dependence of said measured temperature.

15. A climate-controlled freight container (10), comprising: - a cargo compartment (20); - cooling system (30) having at least two cooling modules (40) and anair distribution arrangement (21), configured to distribute air from said coolingmodules (40) around and/ or into said cargo compartment (20) and back; - a control unit (50) configured to control an operation of said coolingsystem (30); wherein said control unit (50) being configured to instruct said coolingsystem (30) to cool down said cargo compartment (20) of said freight container(10) to a predef1ned target temperature,characterized in that said control unit (50) being further configured to instruct said coolingsystem (30) to equalize a temperature distribution within said cargocompartment (20) during a predetermined equalizing period; wherein said control unit (50) being further configured to instruct saidcooling system (30) to performing an individual cooling module test for all saidat least two cooling modules (40), one at a time; whereby, as being comprised in said individual cooling module test,said control unit (50) being further configured to instruct said cooling system(30) to operate a single cooling module (40) to controlling said cargocompartment (20) to have a constant temperature during a predeterminedperiod; and - a power meter (80), configured to measuring a power consumption of said single cooling module (40) during said predetermined period.

16. The climate-controlled freight container according to claim 15,characterized in that said control unit (50) being further configured toevaluate a variance in power consumption for each individual cooling module (40) measured by said power meter (80). 24AMENDED CLAIMSANNOTATED VERSION

17. The climate-controlled freight container according to claim 15 or 16,characterized in that said control unit (50) being further configured tocalculate a total power consumption for each individual cooling module (40), as well as an average total power consumption for all cooling modules (40).

18. The climate-controlled freight container according to claim 16 or 17,characterized in that said control unit (50) being further configured toindicate a suspected cooling module failure in a first cooling module (40) as aresponse to at least one of: said variance in power consumption of said first cooling module(40) exceeds a predetermined value; and if being dependent on claim 17, said total power consumption forsaid first cooling module (40) differs from said average power consumption by more than a predetermined fraction.

19. The climate-controlled freight container according to any of the claims15 to 18, characterized in that said control unit (50) being further configured to monitoring a passive warming-up of said cargo compartment (20).

20. The climate-controlled freight container according to claim 19,characterized in that said control unit (50) being further configured to,during or after said monitoring, indicate a suspected cargo compartmentisolation failure as a response to an initial warming-up rate eXceeding a first limit value.

21. The climate-controlled freight container according to claim 20,characterized by further comprising: - a temperature meter (82), configured for measuring a temperatureoutside said cargo compartment (20) ; whereby said first limit value is determined in dependence of said measured temperature. AMENDED CLAIMSANNOTATED VERSION

22. The climate-controlled freight container according to any of the claims15 to 21, characterized by further comprising: - at least two cargo compartment temperature sensors (53A),measuring temperatures at at least two locations within said cargo compartment (20) during said predetermined equalizing period.

23. The climate-controlled freight container according to claim 22,characterized in that said control unit (50) being further configured todetermine a highest temperature difference between temperatures at said at least two locations at an end of said predetermined equalizing period.

24. The climate-controlled freight container according to claim 22 or 23,characterized in that said control unit (50) being further configured todetermine a duration of a transient time until said temperatures at said at least two locations reaches a steady-state temperature.

25. The climate-controlled freight container according to claim 23 or 24,characterized in that said control unit (50) being further configured toindicate a suspected air distribution failure as a response to at least one of:said highest temperature difference exceeds a predeterminedvalue; andif being dependent on claim 24, said transient time exceeds a predetermined time limit.

26. The climate-controlled freight container according to any of the claims15 to 25, characterized in that said control unit (50) being further configuredto measure a cooling-down time from a start of said cooling system (30) until said predefined target temperature is reached.

27. The climate-controlled freight container according to claim 26,characterized in that said control unit (50) being further configured toindicate a general operation error warning as a response to a cooling-down time exceeding a second limit value. AMENDED CLAIMSANNOTATED VERSION

28. The climate-controlled freight container according to c1aim 27,characterized by further comprising: - a temperature meter (82), configured for measuring a temperatureoutside said cargo compartment (20) ; Whereby said second limit value is determined in dependence of said measured temperature.