SE545019C2

SE545019C2 - Climate-control container and climate-control method for a container

Info

Publication number: SE545019C2
Application number: SE2051161A
Authority: SE
Inventors: Anders Herolf; Lars Edvinsson
Original assignee: Envirotainer Eng Ab
Priority date: 2020-10-02
Filing date: 2020-10-02
Publication date: 2023-02-28
Also published as: WO2022071855A1; SE2051161A1

Abstract

A climate-controlled container (10) comprises a cargo compartment (20) and a climate control system (50) and at least one internal temperature sensor (52A-C) arranged for measuring a temperature inside the cargo compartment and/or in an air-flow to/ from the cargo compartment. The climate control system provides a flow of temperature-controlled air to the cargo compartment, maintaining the temperature of the cargo compartment within a temperature range based on temperature measurements of the internal temperature sensors according to a steady- state control schedule. The climate control system comprises at least one external temperature sensor (70), arranged for measuring a temperature outside the cargo compartment and outside the air-flow to/ from the cargo compartment. The climate control system is configured to activate a temperature-shock control schedule if an absolute value of a temperature change of the external temperature sensor exceeds a predetermined threshold in order to maintain the temperature of the cargo compartment.

Description

TECHNICAL FIELD The present invention relates in general to containers and in particular to methods and arrangements for climate-controlled containers.

BACKGROUND Today, transportation of goods Worldwide is a huge business, having impact on the daily life of substantially all people around the World. Many products are produced far from the location Where they are assumed to be consumed or used, and transportation is therefore crucial. Many products today are sensitive for storage/ transportation times, the environment, and physical exposure of e.g. vibrations or shocks. For shortening the transportation time, air-freight is often used.

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

A fundamental issue in the technical field of climate-controlled air-freight containers based on battery power is the available range of autonomy. Typically, air-freight containers have to have enough power stored in its batteries for the expected operation of the climate system and preferably also a safety margin. HoWever, battery capacity is closely connected to Weight, and lO for air-freight, increased weight is highly unwanted. Consequently, there has to be a compromise between the autonomy time for a climate system of a container and the allowable Weight for the batteries. It is therefore a request within the field of climate-controlled air-freight containers to minimize the power consumption and thereby optimize the autonomy range.

The climate systems of today are typically designed for an operation during constant or slowly varying temperature exposures. The control schemes are very efficient indeed to handle stable ambient temperature conditions. In many cases are the systems also dedicated for delivering an internal container temperature within a predetermined temperature range.

In general, the climate control systems are less efficient to handle large changes in ambient temperatures, in particular if the changes are fast. In air- freight, the containers are moved forth and back from air planes and storage spaces. During ﬂights, the temperatures in the air-plane are typically relatively stable, typically at a relative low temperature, e.g. 5-10°C However, when the containers are de-loaded from the air planes, it is not uncommon that they are exposed for much higher temperatures, in some places up to 30-50°C. In other places, the outside temperatures could instead be very cold, down to -30-50°C. In such situations, the climate control system of the containers is heavily loaded. Since these temperature changes typically also are relatively fast, in many cases within a couple of minutes, the control schemes are often not optimized for such situations. Since most climate-control systems are relying on measurements of internal sensors in the cargo compartment, there will typically be a delay before the climate-control system will experience the results of the ambient temperature change, since the containers typically are well insulated. When the final change is noticed, the actions to mitigate the heat or cold shock typically have to be quite drastic. Such high-intensity operation normally requires large amounts of electrical power, which reduces the overall autonomy range for the container. lO At some airports, in particular at airports in very cold or very hot regions, there are efforts made to try to load and unload the containers from the airplanes in a temperature-controlled area, i.e. typically indoors or in special air locks. HoWever, this requires large efforts and investments in building facilities and makes the goods handling very inefficient and thereby expensive.

SUMMARY A general object is to provide energy-efficient methods and devices for air- freight containers that mitigates the high load caused by fast ambient temperature changes.

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 climate-controlled container, comprises an enclosure defining a cargo compartment and a climate control system. The climate control system is configured for controlling a temperature of the cargo compartment by providing a ﬂoW of temperature-controlled air around and/ or into the cargo compartment. The climate control system comprises at least one internal temperature sensor arranged for measuring a temperature inside the cargo compartment and/ or in an air-ﬂoW to and/ or from the cargo compartment. The climate control system is configured to maintain the temperature of the cargo compartment Within a predetermined allowed temperature range based on temperature measurements of the at least one internal temperature sensor according to a steady-state control schedule. The climate control system comprises at least one external temperature sensor. The external sensor is arranged for measuring a temperature outside the cargo compartment and outside the air-ﬂoW to and from the cargo compartment. The climate control system is configured to maintain the temperature of the cargo compartment Within the predetermined temperature range further based on a time evolution of measurements of the at least one external temperature sensor according to a temperature-shock control schedulekgtjgggi lO In a second aspect, a climate control method for a container comprises measuring of a temperature inside a cargo compartment of the container and/ or in an air-ﬂoW to and/ or from the cargo compartment. The temperature of the cargo compartment is maintained Within a predetermined allowed temperature range based on the temperature measurements of the temperature inside the cargo compartment and/ or in the air-ﬂoW to and/ or from the cargo compartment, by use of a steady-state control schedule. At least one external temperature is measured. The external temperature is a temperature outside the cargo compartment and outside the air-ﬂoW to and from the cargo compartment. The step of maintaining the temperature of the cargo compartment Within the predetermined allowed temperature range is thereby further based on a time evolution of the at least one external temperature, by use of a temperature-shock control schedule_.\___" I m; _\ One advantage With the proposed technology is that the power-consumption during exposure for fast ambient temperature changes is reduced. Other advantages Will be appreciated When reading the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS lO The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which: FIG. 1 is a diagram of an example of a temperature evolution in an container; FIG. 2 is a diagram of an example of a temperature evolution in an container employing a temperature-shock control schedule; FIG. 3 is a cross-sectional view of an embodiment of an container; FIG. 4 is a diagram illustrating effects of differences in temperature increase rates; and FIG. 5 is a ﬂow diagram of steps of an embodiment of a climate control method for an container.

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, the same 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 to begin with a brief overview of the thermal transport properties of an air-freight container.

One basic requirement of a climate-controlled container is that it should have a thermally insulated cargo compartment. The total leak of thermal energy in or out from the cargo compartment will typically show up as part of the total power-consumption of the climate-control system. It is therefore common to build the container with highly thermal insulated walls. lO As a consequence, any temperature changes outside the cargo compartment Will not immediately be recognized by sensors placed within the cargo compartment. It Will take some time before e.g. a heat wave, caused by an increased ambient temperature, has travelled through the insulation of the walls and starts to inﬂuence the internal temperatures of the cargo compartment. There is thus a certain time delay in the measurements provided by the internal sensors. There is also an analogue behavior for cold WaVC S .

Moreover, when such a heat wave eventually has penetrated the insulation of the container, the entire material of the wall, including the insulation, has already been heated up in different degrees. The heat energy that is entering into the cargo compartment will therefore increase relatively rapidly, even if the increase rate is lower than on the outside. The typical steady state climate- control system is adapted to react on small temperature changes quite slowly, in order not to turn on and off part systems too often, which normally is associated with high power consumption. Due to this behavior, the reaction on a rapid temperature change may also be further delayed, and in order to maintain the temperature of the cargo compartment within requested ranges, high-power activities have to be started.

A typical behavior can be schematically illustrated by the diagram of Figure 1. The time evolution of three curves are illustrated. Curve 201 illustrates the temperature of the outer surface of the container, which rapidly follows the ambient temperature. Curve 202 illustrates the temperature of the inner wall of the cargo compartment. Curve 203 illustrates the temperature at a position of a temperature sensor within the cargo compartment. In the diagram, there are also some threshold or target temperatures marked. Target temperature 204 is the target temperature for the cargo compartment, towards which the climate-control should aim. Threshold temperature 205 is the temperature at which the steady-state operation is to be changed by increasing the cooling action or decreasing the heating action. Similarly, threshold temperatureis the temperature at which the steady-state operation is to be changed by decreasing the cooling action or increasing the heating action. Threshold temperatures 206 and 208 represent the boundaries of the allowed temperature range for the cargo compartment.

The steady-state situation from the start involves an ambient temperature TO, and thereby an outer surface temperature 201, that is somewhat lower than the target temperature 204. This situation could e.g. be the situation during a ﬂight. The cargo compartment sensor temperature 203 is equal to the target temperature 205. The inner wall temperature 202 is almost equal to the cargo compartment temperature At time t0, the ambient temperature increases to T1. This could e.g. correspond to that the container is de-loaded from the airplane and stored in an open-air storage. The outer surface temperature 201 follows this temperature change quite rapidly. However, the insulation of the container prohibits the heat to reach the interior of the container immediately. However, the heat energy starts to penetrate the insulation. This "heat wave" slowly propagates through the insulation and reaches eventually the inner wall. At the same time, the abruptness of the temperature change is smeared out in time, as can be seen for curve 202. The temperature of the inner wall will in turn affect the cargo compartment temperature, that also will start to increase, see curve 203. However, this increase is further delayed compared to the inner wall.

At time t1, the cargo compartment sensor temperature 203 has reached the threshold 205 and the steady-state control system is trigged to change the settings to reduce the heating action that was operating during the ﬂight to compensate for that the ambient temperature was lower than the target temperature. The (quasi) steady-state control system may even notice that the increase in cargo compartment sensor temperature 203 is relatively fast and may therefore possibly also start some additional cooling actions. Since the inner wall temperature 202 has increased considerably, the heat energy lO transferred into the cargo compartment is relatively large and a high-intensity operation has to be applied in order to keep the cargo compartment sensor temperature 203 below the high temperature limit 206 of the allowed temperature range.

Eventually, this high-intensity action fulf1lls its purpose and the cargo compartment sensor temperature 203 is turned down again and a new steady- state operation can be established at time t2. After some remaining ﬂuctuations, the cargo temperature becomes stable around time t However, the fast action may result in a certain inertia of the temperature change and the cargo compartment sensor temperature 203 and the inner wall temperature 202 may even go down below the target temperature. In a serious case, it may even be necessary to actively increase the cargo compartment temperature in order to be kept above the limit 208. The fast action will, however, typically give rise to some temperature ﬂuctuations before the temperature again stabilizes around the target temperature. All these actions require large amounts of power, and the charge of the batteries is rapidly reduced, resulting in a reduced autonomy period.

If a faster detection of the new circumstances could have been performed, precautionary measures could have been taken, which reduces the total power consumption. An example is schematically illustrated in Figure The outside temperature trend is the same as in Figure 1. However, if the ambient temperature is monitored, already at time t4 it can be concluded that a fast temperature increase has occurred. Already at that time, precautionary measures may be taken, long before the heat reaches the cargo compartment. In this particular case, the heating used during the initial steady-state may be turned off. The heat energy stored in the system will then tend to decrease the cargo compartment sensor temperature 203 below the target temperature. This tendency can also be amplified by starting a very gentle cooling action.

The cargo compartment sensor temperature 203 and the inner wall temperature 202 Will decrease but can still be controlled to be higher than the limit temperature When the heat Wave induced by the increased ambient temperature starts to penetrate the insulation of the container, the cargo compartment sensor temperature 203 and the inner Wall temperature 202 Will again increase. The system is now aware of the reasons for such an increase and may increase the cooling action of the climate-control system at an earlier stage, e.g. When the cargo compartment sensor temperature 203 passes the target temperature 204 at time t5. The ﬂuctuations in the cargo compartment sensor temperature 203 and the inner Wall temperature 202 can by such actions be kept much smaller than Without the precautionary measures. The heat shock operation can therefore in many cases be kept short and less intense than for the system of Figure 1. At time t6, the system can return to a steady-state control schedule, but With a certain level of cooling instead of heating. The total energy consumption is drastically reduced, resulting in an increased autonomy period.

Figure 3 illustrates an embodiment of a climate-controlled air-freight container 10 in a cross-sectional view. The freight container 10 is defined by an outer shell 12. The cargo compartment 20 is defined Within the outer shell 12 by an enclosure 13 comprising a ﬂoor 16, a ceiling 14 and Walls 18. The freight container 10 also comprises a climate control system 50. The climate control system 50 is configured for controlling a temperature of the cargo compartment 20 by providing a ﬂoW 100 of temperature-controlled air around and/ or into the cargo compartment 20. The climate control system 50 is in this embodiment situated in a control compartment 30 that is separated from the cargo compartment 20 by a partition Wall 32. The climate control system 50 receives a return air-ﬂoW 104 going into the climate control system 50 through an input pipe 38 and provides an air-ﬂoW 102 going out from the climate control system 50 through an output pipe 36. The ﬂoW 100 of temperature-controlled air is provided in vicinity of the ceiling 14 of the cargo compartment In this particular embodiment, this distribution of the ﬂow 100 of temperature-controlled air is supported by an upper gas-ﬂow distributer plate 40. The ﬂow 100 of temperature-controlled air is here directed from the output pipe 36 to the space between the ceiling and the upper gas-ﬂow distributer plate 40. The upper gas-ﬂow distributer plate 40 does not cover all the distance to the walls and leaves openings for climate-conditioned gas to ﬂow 108 into the main cargo compartment. Likewise, there is in this particular embodiment also a side gas-ﬂow collector plate 42, placed with a small distance to the wall separating the cargo compartment 20 from the control compartment 30. Gas leaving the cargo compartment 20 ﬂows beneath the edge of the side gas-ﬂow collector plate 42 and upwards along the wall into the input pipe The climate control system 50 comprises at least one internal temperature sensor 52A-C arranged for measuring a temperature inside the cargo compartment 20 and/ or in an air-ﬂow to 104 and/ or from 102 the cargo compartment.

First internal temperature sensors 52A are placed at different locations in the cargo compartment. In the present embodiment, two first internal temperature sensors 52A are placed at the side wall 18, two first internal temperature sensors 52A are placed at the side gas-ﬂow collector plate 42 and one first internal temperature sensor 52A is placed at an edge of the upper gas-ﬂow distributer plate 40. A second internal temperature sensor 52B is placed in the gas-ﬂow 102 going out from the climate control system 50. A third internal temperature sensor 52C is placed in the gas-ﬂow 104 going into the climate control system 50. In other embodiments, other combinations of internal temperature sensors may be provided.

The internal temperature sensors 52A-C are communicationally connected to a control unit 54 of the climate control system 50. The control unit 54 is configured for controlling the operation of the climate control system 50 toobtain the temperature conditions of the ﬂow 100 of temperature-controlled air. This control is based on the measurements of the internal temperatures obtained by the internal temperature sensors 52A-C. The climate control system 50 is configured to maintain the temperature of the cargo compartment 20 within a predetermined allowed temperature range based on temperature measurements of the internal temperature sensor or sensors 52A-C according to a steady-state control schedule.

The climate control system 50 further comprises at least one external temperature sensor 70 arranged for measuring a temperature outside the cargo compartment 20 and the air-ﬂow to 104 and from 102 the cargo compartment 20. In the present embodiment, one external temperature sensor 70 is located within the control compartment 30. This placement protects the one external temperature sensor 70 from being damaged in interaction with different kinds of transporting or lifting equipment. The control compartment 30 is typically well ventilated and the temperature within the control compartment 30 typically follows the ambient temperature very closely. In this particular embodiment, another external temperature sensor 70 is located in a space at the top of the freight container 10, recessed into the outer surface of the freight container 10. Analogously, another external temperature sensor 70 is located in an outer wall of the freight container 10, recessed into the outer surface of the freight container 10. The external temperature sensor or sensors 70 are communicationally connected to the control unit 54 of the climate control system 50. The climate control system 50 is configured to maintain the temperature of the cargo compartment 20 within the predetermined temperature range further based on a time evolution of measurements of the external temperature sensor or sensors 70 according to a temperature-shock control schedule.

If an ambient temperature of a container varies slowly, a steady-state control schedule will typically take care of the adaptation of cooling/ heating operations to compensate for the changed conditions. This may e.g. be the case if a container is stored in a storage where the ambient temperature may lOvary e.g. 10°C between the night and day. In such cases, the temperature- shock control schedule is believed to be superﬂuous. However, at fast changing ambient temperatures, the need for the temperature-shock control schedule is large. This is schematically illustrated in Figure 4. The curves 201 and 203 from Figure 1 are included as references. If the ambient temperature varies slowly, such as illustrated by the curve 201", the need for decreased heating and increased cooling of the cargo compartment temperature is successively increased. However, the changes are slow, and the ordinary control scheme will manage to keep the variations small, as seen from the curve 203". Note that the total change AT in ambient temperature is the same in both cases.

For this reason, the time evolution of measurements of the external temperature sensor or sensors is important for the decision of whether or not the temperature-shock control schedule should be applied. It is thus the time derivate of the external temperature that should be monitored rather than the absolute temperature difference. At the same time, fast external temperature changes, but with a very limited amplitude, e. g. one or a few degrees, will not require any special treatment.

Therefore in a preferred embodiment the climate control system 50 is configured to activate the temperature-shock control schedule if an absolute value of a temperature change of the external temperature sensor within a predetermined trend time exceeds a predetermined threshold. Such a discrimination will eliminate large but slow temperature changes as well as fast but tiny temperature changes. The predetermined trend time and the predetermined threshold can be adapted to each individual system to obtain an optimized overall optimization. This approach will also handle both increasing and decreasing ambient temperatures by a common threshold.

Figure 5 illustrates a ﬂow diagram of steps of an embodiment of a climate control method for a container. In step S2, a temperature inside a cargo compartment of the container and/ or in an air-ﬂow to and/ or from the cargocompartment is measured. In step S4, the temperature of the cargo compartment is maintained within a predetermined allowed temperature range. The maintaining is based on the temperature measurements of the temperature inside the cargo compartment and/ or in the air-ﬂow to and/ or from the cargo compartment, by use of, as illustrated by step S6, a steady- state control schedule. In step S8, at least one external temperature is measured. The external temperature is a temperature outside the cargo compartment and outside the air-ﬂow to and from the cargo compartment.

In step S10, it is checked whether the time evolution of the external temperature indicates a risk for a temperature shock. If no risk is present, the process returns to step S2. If the time evolution of the external temperature calls for additional actions, the process continues to step S12. In step S12, which is part of the step S4 of maintaining the temperature of the cargo compartment within the predetermined allowed temperature range, a temperature-shock control schedule is used.

Eventually, when the temperature-shock control schedule is finished, the process returns to step S In a preferred embodiment, the temperature-shock control schedule is activated if an absolute value of a temperature change of the at least one external temperature within a predetermined trend time exceeds a predetermined threshold.

The principles of the temperature-shock control schedule can be designed in different ways. One approach is to use the temperature-shock control schedule to modify the steady-state control schedule, e.g. by changing different set temperatures or power limitations.

However, since the steady-state control schedule typically is optimized for small adjustments of heating and cooling, it is preferred to use a separate temperature-shock control schedule, overriding the steady-state control lOSchedule. In other WordS, in one embodiment, the temperature-Shock control Schedule compriSeS overriding the Steady-State control Schedule if the abSolute value of the temperature change of the at leaSt one external temperature Within the predetermined trend time exceedS the predetermined threShold.

The overriding thuS alloWS for operation modeS that are not uSually allowed by the Steady-State control Schedule. In the caSe of a rapidly increaSing ambient temperature, any ongoing heating of the cargo compartment becomeS unneceSSary, more or leSS regardleSS of the actual meaSured internal temperature. If the SyStem already uSeS cooling, Such a cooling can be increaSed beyond What normally iS uSed.

In other WordS, in one embodiment, the Step of overriding in turn compriSeS the Step of increaSing a cooling action or decreaSing a heating action on the cargo compartment if a temperature increaSe of the at leaSt one external temperature, Within the predetermined trend time, exceedS the predetermined threShold.

An analogue Situation iS preSent if there iS a rapid decreaSe in ambient temperature. In one embodiment, the Step of overriding in turn compriSeS the Step of decreaSing a cooling action or increaSing a heating action on the cargo compartment if a temperature decreaSe of the at leaSt one external temperature, Within the predetermined trend time, exceedS the predetermined threShold The Start of the uSe of the temperature-Shock control Schedule iS thuS trigged by the ambient temperature increaSe rate. HoWever, Such a Schedule iS not optimized for continuouS operation for longer periodS. Therefore, there are preferably Some criteria for Stopping the uSe of the temperature-Shock control Schedule. lO One possible choice is to use time. The temperature-shock control schedule can thus be utilized during a certain override time. After this time is ended, the operation returns again to the ordinary steady-state control schedule. The simplest choice is to have a constant override time that is valid for all occasions. HoWever, a temperature shock of 15°C is probably mitigated in a shorter time than a temperature shock of 45°C. Therefore, in a preferred embodiment, the overriding of the steady-state schedule is performed during an override time being determined based on the time-evolution of the at least one external temperature. This time evolution can take both absolute temperature differences as Well as the temperature change rate into account. In such a Way, different override times can be used for different situations. The exact values of these override times to obtain an optimized operation Will depend on the actual climate control system and have to be adapted for at least each type of system.

An alternative Way of stopping the temperature-shock control schedule is to rely on the measure internal temperatures. When the original "temperature shock Wave" has been taken care of by the climate control system operating according to the temperature-shock control schedule, remaining transient damping may often be eff1ciently handled by the steady-state control schedule. The stopping of the temperature-shock control schedule may e.g. be based on reaching an override temperature, possibly after a certain initial period. As in the case of the override time, this override temperature may also be determined based on the actual measured ambient temperature rise of fall.

In other Words, in one embodiment, the overriding of the steady-state control schedule is performed until an override temperature is reached in the cargo compartment, the override temperature being determined based on the time- evolution of the at least one external temperature.

The above described measures are preferably performed in the same control unit as is handling the steady-state operation. This means that, preferably, the climate control system is configured to allow the temperature-shock lOcontrol schedule to override the steady-state control schedule if the absolute value of the temperature change of the external temperature sensor Within the predetermined trend time exceeds the predetermined threshold.

In one embodiment, the climate control system is conf1gured to increase a cooling action or decrease a heating action on the cargo compartment if a temperature increase, Within the predetermined trend time, exceeds the predetermined threshold.

In one embodiment, the climate control system is conf1gured to decrease a cooling action or increase a heating action on the cargo compartment if a temperature decrease, Within the predetermined trend time, exceeds the predetermined threshold In one embodiment, the overriding of the steady-state control schedule is performed during an override time being determined based on the time- evolution of the measurements of the at least one external temperature sensor.

In one embodiment, the overriding of the steady-state control schedule is performed until an override temperature is reached in the cargo compartment, the override temperature being determined based on the time-evolution of the measurements of the at least one external temperature sensor.

The above discussions have so far treated the cargo compartment as a homogenous volume With an enclosure having the same thermal conducting properties in all points. HoWever, this is not the fact in reality, Where goods in the cargo compartment may prohibit a free gas circulation and Where the thermal properties of the enclosure components may be different in different locations. The above reasoning does indeed assist in mitigating a thermal shock in general terms, but there might also be additional consideration concerning temperature distributions over the cargo compartment. lOIt is thus common that a changed ambient temperature Will be noticeable at different point in time in different locations within the cargo compartment. It is e.g. common that container corners, e.g. between two walls or between a wall and the ceiling or the ﬂoor, have somewhat higher thermal conductivity than the middle wall parts. Likewise, there may be minor damages, e. g. in wall insulation or door insulation that also increases the thermal conductivity in these areas. Consequently, a changed ambient temperature will first be recognized in the vicinity of such locations. By providing a multitude of temperature sensors 52A within the cargo compartment, differences in temperature at different locations in the cargo compartment can be followed. If one or a few temperature sensors start to measure a change in temperature, while the other do not, different actions can be made.

The reason for such a difference between internal temperature sensors may be different. If the sensors are located close to positions that are believed to suffer from somewhat poorer thermal insulation, it may be a pre-warning of that a general temperature shock is to be expected. The first areas within the cargo compartment to experience the start of the temperature shock are the areas close to poor thermal insulation spots. If this is the case can easily be confirmed by consulting the external temperature measurements. Another reason for an appearing difference between internal temperature sensors may be that the thermal insulation is damaged or that the cargo compartment is partly or fully opened. This may e.g. be caused by transport-trigged damages or by unauthorized intrusion acts.

The increased total energy ﬂow that is associated with such disturbances may be handled by the ordinary climate-control system, e.g. by the procedures presented further above. However, even if the total increase in heat energy transfer may be low, the uneven temperature conditions within the cargo compartment can still cause problems. The difference in temperature distribution within the cargo compartment can be mitigated by further actions. lOIn one embodiment, readings from a multitude of temperature sensors 52A within the cargo compartment are collected. It is then determined if there exist any large differences between the individual readings. This may e.g. be performed by calculating a standard deviation measure of the readings and if that standard deviations larger than a predetermined threshold, a situation with large differences is indicated. Alternatively, an average is calculated, and also a difference between each measure and the average. If the absolute value of any of these differences exceeds a predetermined threshold, a situation with large differences is indicated. When such a situation with large differences is indicated, poor distribution of temperature within the cargo compartment is assumed to be present. In order to mitigate this, the climate-control system increases the ﬂow of climate-controlled air into the cargo compartment to increase the circulation and thereby acting for even out any present temperature differences. The amount of heat/ cold carried by this increased ﬂow may not necessarily be changed. This is typically taken care of by the ordinary control routines. Instead, the ﬂow can be increased by e. g. increasing the speed of fans that are used for providing the climate-controlled air into the cargo compartment.

This monitoring of the evenness of the temperatures within the cargo compartment may be performed at any time, and is preferably constantly available. However, these routines are particularly well suited to be a complement to the regulations made based on the trends for the ambient temperatures.

The embodiments described above are to be understood as a few illustrative examples of the present invention. It will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the scope of the present invention. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible. The scope of the present invention is, however, defined by the appended claims.

Claims

1. A climate-controlled container (10), comprising: an enclosure (13) def1ning a cargo compartment (20): a climate control system (50), configured for controlling a temperature of said cargo compartment (20) by at least one of providing a ﬂoW (100) of temperature-controlled air around said cargo compartment (20) and providing a ﬂoW (100) of temperature-controlled air into said cargo compartment (20); said climate control system (50) comprises at least one internal temperature sensor (52A-C) arranged for at least one of measuring a temperature inside said cargo compartment (20), measuring a temperature in an air-ﬂoW (102) to said cargo compartment (20) and measuring a temperature in an air-ﬂoW (104) from said cargo compartment (20); Whereby said climate control system (50) is configured to maintain said temperature of said cargo compartment (20) Within a predetermined allowed temperature range based on temperature measurements of said at least one internal temperature sensor (52A-C) according to a steady-state control schedule; characterized in that said climate control system (50) comprises at least one external temperature sensor (70) arranged for measuring a temperature outside said cargo compartment (20) and said air-ﬂoW to (102) and from (104) said cargo compartment (20); Whereby said climate control system (50) is configured to maintain said temperature of said cargo compartment (20) Within said predetermined temperature range further based on a time evolution of measurements of said at least one external temperature sensor (70) according to a temperature- shock control schedule, and to activate said temperature-shock control schedule if an absolute value of a temperature change of said external temperature sensor Within a predetermined trend time exceeds a predetermined threshold, said temperature-shock control schedule being a control schedule different from said steady-state control schedule and allowed to override said steady-state control schedule When activated.

2. The climate-controlled container according to claim 1, characterized in that said climate control system (50) is configured to increase a cooling action or decrease a heating action on said cargo compartment (20) if a temperature increase of said external temperature sensor (70), Within said predetermined trend time, exceeds said predetermined threshold.

3. The climate-controlled container according to claim 1, characterized in that said climate control system (50) is conf1gured to decrease a cooling action or increase a heating action on said cargo compartment (20) if a temperature decrease of said external temperature sensor (70), Within said predetermined trend time, exceeds said predetermined threshold

4. The climate-controlled container according to any of the claims 1 to 3, characterized in that said overriding of said steady-state control schedule is performed during an override time being determined based on said time- evolution of said measurements of said at least one external temperature sensor (70).

5. The climate-controlled container according to any of the claims 1 to 3, characterized in that said overriding of said steady-state control schedule is performed until an override temperature is reached in said cargo compartment (20), said override temperature being determined based on said time-evolution of said measurements of said at least one external temperature sensor (70).

6. The climate-controlled container according to any of the claims 1 to 5, characterized in that said climate control system (50) comprises a multitude of internal temperature sensors (52A) arranged for measuring a temperature inside said cargo compartment (20), Whereby said climate control system (50) is configured to determine Whether an uneven temperature distribution Within the cargo compartment is present based on measurements of said multitude of internal temperature sensors (52A), and Whereby said climate control system (50) is conf1gured to, as a response to a determined said uneventemperature distribution, increase the amount of air ﬂowing into said cargo compartment.

7. A climate control method for a container (10), comprising the steps of: - at least one of (S2) measuring a temperature inside a cargo compartment (20) of said container (10), measuring a temperature in an air- ﬂow (102) to said cargo compartment (20) and measuring a temperature in an air-ﬂoW (104) from said cargo compartment (20) ; - maintaining (S4) said temperature of said cargo compartment (20) Within a predetermined allowed temperature range based on said temperature measurements of said at least one of said temperature inside said cargo compartment (20), said temperature in said air-ﬂoW (102) to said cargo compartment (20) and said temperature in said air-ﬂoW (104) from said cargo compartment (20), by use of a steady-state control schedule (S6), characterized by the further step of: - measuring (S8) at least one external temperature, said external temperature being a temperature outside said cargo compartment (20) and said air-ﬂoW to (102) and from (104) said cargo compartment (20) ; Whereby said step of maintaining (S4) said temperature of said cargo compartment Within said predetermined allowed temperature range is further based on a time evolution of said at least one external temperature, by use of a temperature-shock control schedule (S12) Which is activated if an absolute value of a temperature change of said at least one external temperature Within a predetermined trend time exceeds a predetermined threshold, said temperature-shock control schedule being a control schedule different from said steady-state control schedule and comprising overriding said steady-state control schedule (S6) When activated.

8. The climate control method according to claim 7, characterized in that said step of overriding in turn comprises the step of increasing a cooling action or decreasing a heating action on said cargo compartment (20) if a temperature increase of said at least one external temperature, Within said predetermined trend time, exceeds said predetermined threshold.

9. The climate control method according to claim 7, characterized in that said step of overriding in turn comprises the step of decreasing a cooling action or increasing a heating action on said cargo compartment (20) if a temperature decrease of said at least one external temperature, Within said predetermined trend time, exceeds said predetermined threshold

10. The climate control method according to any of the claims 7 to 9, characterized in that said overriding of said steady-state schedule is performed during an override time being determined based on said time- evolution of said at least one external temperature.

11. The climate control method according to any of the claims 7 to 9, characterized in that said overriding of said steady-state control schedule is performed until an override temperature is reached in said cargo compartment (20), said override temperature being determined based on said time-evolution of said at least one external temperature.

12. The climate control method according to any of the claims 7 to 11, characterized in that said step of at least one of (S2) measuring a temperature inside a cargo compartment (20) of said container (10), measuring a temperature in an air-ﬂoW (102) to said cargo compartment (20) and measuring a temperature in an air-ﬂoW (104) from said cargo compartment (20) comprises measuring a temperature at a multitude of locations inside said cargo compartment (20), Whereby said method comprises the further steps of: - determining Whether an uneven temperature distribution Within the cargo compartment is present based on measurements of said multitude of internal temperature sensors (52A), and - increasing, as a response to a determined said uneven temperature distribution, the amount of air ﬂoWing into said cargo compartment.