The invention concerns a cargo space unit of a vehicle, comprising at least one structure defining a cargo space and an air temperature regulating device. The invention also relates to an air temperature regulating device.

Background

During the transport of miscellaneous goods, it is often desirable to keep the cargo space of a vehicle transporting the goods at approximately the same temperature, regardless of the temperature outside of the van. For example, for edibles, a temperature of between 2 and 8 degrees Celsius may be recommended, while for many types of medication and other goods "room temperature", conventionally taken to be about 15-25 degrees Celsius, is the desired temperature.

While these desired temperatures may simply be a matter of preference, or may be recommended to prevent perishing of goods, in certain cases, in particular when the goods comprise medication, a certain temperature range is required by law, or will be in the near future.

There is therefore a need for a heater (and preferably also a cooler) capable of maintaining a temperature of a cargo space of a vehicle within a certain range of temperatures for an extensive range of outside temperatures.

In existing heated cargo spaces, heating is generally provided by a fuel-driven generator. This has as a disadvantage that it may not be very fuel efficient. Furthermore, it requires thorough integration with the vehicle, in particular with the engine of the vehicle. This has as a consequence that once the heater are installed, it is not cost-efficient to remove it from a vehicle, for instance to install it in another vehicle. This also means that a functioning heater may often be discarded just because the transport vehicle they were installed in was discarded.

Other systems use heat from the cooling fluid of the engine to heat the cargo space.

Unfortunately, this is not a very reliable source of heat, especially considering engines are getting ever more efficient and produce less and less waste heat. Using the cooling fluid may also impede the functioning of the engine, as it may not be able to stay at a required temperature for proper function.

Combinations of the above two techniques may also be applied, but even these combinations usually have one or more of the above-mentioned disadvantages.

Therefore, a solution is desirable which is not fuel driven; does not draw heat from the cooling fluid of the engine; is easily transferrable between vehicles and/or cargo spaces, and/or can supply sufficient heating capacity to heat a cargo space to desired temperatures even with a wide range of outside (ambient) temperatures. According to a first aspect a cargo space unit of a vehicle is provided, the cargo space unit comprising at least a structure defining a cargo space and an air temperature regulating device, wherein the air temperature regulating device comprises:

- a heat pump comprising a compressor capable of being connected to an electrical power source of the vehicle and of being powered thereby,

- a first inlet connected to the heat pump and configured to supply ambient air from the surroundings of the cargo space to the heat pump,

- a first outlet connected to the heat pump and configured to discharge air from the heat pump to the surroundings,

- a second inlet for the supply of air from the cargo space to the heat pump,

- a second outlet for the discharge of air from the heat pump to the cargo space, wherein the air temperature regulating device is configured to be positioned inside the cargo space of the vehicle.

Since the air regulating device can be positioned inside the cargo space, the installation of the cargo space unit is easy and does not require any substantial modifications to the construction of the vehicle. The cargo space unit can be retrofitted in a simple manner with the temperature regulating device. Another advantage is that a temperature regulating device installed in a first vehicle can be easily transferred to a second vehicle. This makes it possible to use the temperature regulating device in different vehicles, for instance when an old vehicle is replaced by a new vehicle. This may help to reduce the operational costs of the air regulating unit.

According to an embodiment the air temperature regulating device is configured to be connected to the ambient air through the first inlet and first outlet only. No further technical measures need to be taken to make the air infeed and air discharge of the air regulating device operational.

The electrical power for powering the air regulating device, for instance the compressor thereof, can be made available by the electrical power source already present in a vehicle, for instance the battery and/or the generator of the engine. This means that the device can be easily installed in a vehicle, without the need for structural alterations. Furthermore the air temperature regulating device can be made compact and easily portable, if required. For instance, in a preferred embodiment, the temperature regulating device is arranged in a portable housing, the housing comprising connection members configured to releasably connect the housing to the structure of the cargo space. Since the air temperature regulating device may be releasably fixed in the cargo space, it is possible to transfer to another, similar cargo space unit. The properties of the heat pump are chosen such that at negative outside temperatures a sufficiently high efficiency is reached such that the cargo space unit can be brought to and kept at a desired positive temperature, for instance a temperature between 15 and 25 degrees Celsius.

In an embodiment of the invention at least one of the stroke volume of the compressor, the type of working fluid, and the size of the evaporator are configured to increase the efficiency of the heat pump at negative outside temperatures.

In a further embodiment the heat pump is capable of achieving a temperature difference between the ambient air temperature and the air temperature inside the cargo space unit of at least 20 degrees Celsius, preferably at least 30 degrees Celsius, more preferably at least 40 degrees Celsius.

The air temperature regulating device may be connected to the electrical power supply of the vehicle through one or more electric (power) cables. Power may be supplied to the compressor through these one or more electrical cables. The air temperature regulating device may be arranged at a position close to the electrical power source of the vehicle, preferably at the front portion of the cargo space unit. In this manner the electric power cables between the power source and the compressor may be kept relatively short.

In a preferred embodiment the first inlet opens to the bottom of the vehicle and the first outlet opens to the top and/or the front of the vehicle (i.e. the front of the cargo space of the vehicle, for instance between the front wall and the cabin of the vehicle). In winter time, i.e. when the ambient temperatures are low and the cargo space needs to be heated, the temperature near the bottom of the vehicle may be somewhat higher than the air temperature elsewhere as result of the exhaust fumes from the engine. More specifically, the air inlet may be arranged close to the exhaust of the engine so as to have maximum benefit of the raised ambient temperature.

The first and second inlet may comprise of different tubes passing through the walls, floor and/or ceiling of the cargo space. In a specific embodiment the first inlet and the first outlet are embodied as a double -walled tube.

The cargo space unit may comprise a first temperature sensor configured to measure the temperature inside the cargo space unit, and a control system to adapt the operation of the air temperature regulating device on the basis of a difference between the measured temperature and a pre-set desired temperature.

In embodiments the heat pump of the air temperature regulating device comprises a working fluid conduit and a compressor for guiding the working fluid through an evaporator and condenser. The heat pump and the working fluid used therein may be optimized for cooling the air within the cargo space. The heat pump may have only one working fluid circuit for circulating only one type of working fluid through the evaporator and condenser. In case the heat pump is of the reversible type, this one type of working fluid is used both to provide cool air in the cargo space when the cargo space needs to be cooled and to provide heated air in the cargo space when the cargo space needs to be heated. In other embodiments use is made of a first heat pump that is optimized for cooling of the air in the cargo space and a second heat pump optimized for heating the air in the cargo space. In further embodiments the heat pump comprises a first working fluid conduit, a second working fluid conduit and a compressor for guiding the first working fluid through a first evaporator and first condenser in case of cooling the air in the cargo space and for guiding the second working fluid through a second evaporator and second condenser in case of heating up the air in the cargo space. The first and second working fluids may be different types of working fluids, each type of working fluid being selected to best perform its task (i.e. the task of providing cool air or the task of providing warm air into the cargo space).

The cargo space unit may comprise a first compressor for transporting the first working fluid and a second compressor for transporting the second working fluid. In a preferred embodiment both heat pumps make use of one common compressor only which is configured to transport the first working fluid through the first working fluid circuit and the second working fluid through the second working fluid circuit.

In embodiments the air temperature regulating device comprises a reversible heat pump in order to reverse the operation of the heat pump, i.e. change the operation from cooling to heating or from heating to cooling. The operation of the air temperature regulating device may be reversed manually or, preferably, by means of a control system.

The cargo space may be the cargo space of a delivery van or light van. In other embodiments the cargo space comprises a cargo container to be removably placed on the chassis or frame of a truck or similar vehicle. Typically the internal volume of the cargo space ranges from 5 to 15 m ³ .

In order to reduce the temperature variation inside the cargo space during variations in the ambient temperature and in order to reduce the cooling/heating capacity of the air temperature regulating device the cargo space is preferably thermally insulated. To this end the structure of the cargo space unit may have been provided with thermal insulation material (for instance, a layer of rock wool or mineral wool). Preferably all construction elements forming the structure of the cargo space (i.e. the walls, floor, ceiling, etc.) have been insulated to at least a minimum extent to enable a high overall insulation of the cargo space. The thermal insulation is selected dependent on the type of vehicle (manufacturer, size, construction, etc.). Generally for smaller vehicles with a relatively small-sized cargo space the insulation value provided by the thermal insulation material may be kept small or insulation can be dispensed with altogether. For larger-sized vehicles the insulation material may play a more important role. In practice a layer of insulating material of several cm, for instance 3 cm or more, preferably more than 4 cm, more preferably more than 5 cm, is employed to insulate the cargo space from its surroundings (i.e. the ambient air).

According to another aspect an air temperature regulating device is provided wherein the device is configured for use in a cargo space unit as defined herein. The device may comprise:

- a heat pump,

- a first inlet connected to the heat pump and configured to supply ambient air from the surroundings of the cargo space to the heat pump,

- a first outlet connected to the heat pump and configured to discharge air from the heat pump to the surroundings,

- a second inlet for the supply of air from the cargo space to the heat pump,

- a second outlet for the discharge of air from the heat pump to the cargo space,

- a compressor capable of being connected to an electrical power source of the vehicle and of being powered thereby.

According to a further aspect a method of transporting pharmaceutical products, for instance medications, in a cargo space unit is provided, the method comprising regulating the temperature inside the cargo space to a temperature in the range of 15-25 degrees Celsius using the air temperature regulating device as defined herein.

Further details and characteristics of the invention will be further illustrated in the following description of several exemplifying embodiments thereof. In the description reference is made to the annexed figures, in which:

Figure 1 shows a vehicle with a cargo space equipped with an embodiment of a heater according to the invention;

Figure 2 shows a freestanding cargo space which may be attached to a vehicle, also equipped with an embodiment of the heating means according to the invention;

Figure 3 shows an embodiment of the heater according to the invention;

Figures 4-6 show a further embodiment of the present invention.

Detailed description of the figures

Figure 1 shows a vehicle with a cargo space unit 1. The cargo space unit 1 may be small, just a few cubic metres. It may also be bigger, up to about 15 cubic meters. With further advances, the presently proposed heater may also be suitable for bigger cargo spaces. In the figure the front wall of the cargo space is the back wall of the cabin of the vehicle. In other types of vehicles (not shown in the figures) a space may be present between the cargo space front wall and the back wall of the cabin. The cargo space unit 1 is equipped with a layer of insulation 5, preferably on all six sides of the cargo space. The thickness of the insulation layer 5 will depend on factors such as the volume of the cargo space, the intended purpose and attendant desired temperatures of the cargo space, the efficiency of the heater, the expected outside temperatures, etc. In tests, it has been shown that for most purposes, a layer of insulation of between 3 and 6 cm, should be sufficient.

The vehicle operates with a conventional fuel engine, which is not shown in the image. The vehicle is also equipped with a battery 21. In general, batteries for this type of vehicle are capable of producing about lkW of electric power.

Also shown in the figure is an embodiment of the air temperature regulating device for the cargo space. The air temperature device comprises a heat pump 4 connected to the battery 21 though electric connection cables 3. There are many possible ways to enable this connection. For example, a simple cable may be routed through the cabin or the sides of the vehicle. In some cases, it may be possible to plug the heat pump 4 into an outlet in the cargo space which is connected to the battery of the vehicle. The skilled person will be able to think of various alternatives which allow a heat pump 4 positioned in the cargo space to be powered by the battery 21 of the vehicle.

The heat pump 4 is positioned inside the cargo space, preferably in a manner in which it is relatively straightforward to remove. The heat pump 4 may be positioned at any point in the cargo space. However, in many cases it is preferable to position it close to the front of the cargo space (wherein the front is the part closest to the driver) as this least impedes the loading and unloading of goods. In some embodiments, the heat pump 4 may be hung from the ceiling of the cargo space unit 1 , while in other embodiments it may be positioned on the floor. Attaching the heat pump 4 at a certain height to the wall of the cargo space unit is also an option.

The general working principle of a heat pump 4 is known to the skilled person, and will be sketched here only in broad details. A heat pump generally comprises a compressor 13, an evaporator 14 and a condenser 15, between which a working fluid 12 circulates.

In a generic heat pump, a first air flow 8 with a certain temperature flows past the evaporator 14. A portion of the heat from this first air flow 8 causes at least a portion of the working fluid 12 to evaporate. The first air flow 8 cools down during this process, and is expelled with a lower temperature. The working fluid 12, which is now at least in part in gaseous form, is then passed through a compressor 13, which compresses it. From the compressor 13, the working fluid 12 goes to the condenser 15, in which the working fluid condenses. This condensation process produces heat, which heats up a second air flow 11 flowing past the condenser 14. Finally, the working fluid 12, which will now again in most cases be wholly or almost wholly in fluid form, is passed back to the evaporator 14 (often after passage through an expansion valve), completing the cycle. Of course many variations on this basic model are possible. Elements which may be varied include, but are not limited to: the type of working fluid; the type of compressor; the configuration and efficiency of the compressor; the shape, size, and configuration of the evaporator and condenser; the materials made to manufacture the evaporator and condenser; the manner of making the air flow; etc.

The energy of the battery 21 of the vehicle is used to power the compressor 13 as well the displacement of the two air flows 8, 11 and the flow of working fluid 12. Other elements which also need electric power may also be powered by the battery 21 of the vehicle.

An advantage of heat pumps is that since one air flow is cooled as another is heated up, a heat pump may also be used for cooling purposes. In particular, by reversing the flow direction of the working fluid, the evaporator may become the condenser and vice versa. Many heat pumps have been designed for this possibility, since a temporary (short) reversal may also serve to remove ice formation that may occur in/on the evaporator.

A reversible heat pump may be used as the desired inside temperature of the cargo space of the vehicle may at times be higher than the outside temperature and at other times lower than the outside temperature.

In the figure, the first air flow 8 is a flow of outside air. In the embodiment depicted in the figures, a first air inlet 6 for the first air flow 8 of ambient air is positioned at the bottom of the vehicle, and the first air flow 8 is expelled through a first air outlet 7 which ends at the top and/or front of the cargo space of the vehicle. This may be beneficial if a vehicle is primarily used in environments with cold climates, as in those circumstances the air under a vehicle may be slightly less cold than the rest of the outside air due to the proximity of the engine.

However, other placements of the first air inlet 6 and first air outlet 7 are also possible, and the skilled person will be able to determine optimal placement depending on the particular vehicle and planned purpose. In particular, it is also possible for the first air inlet 6 and first air outlet 7 to be much closer together, or even for the first air inlet 6 and first air outlet 7 to be embodied as concentric tubes.

The first air inlet 6 and first air outlet 7 are provided with fans or other means of displacing air (not depicted), as well as, if necessary, means for routing the first air flow 8 from the first air inlet 6 past the first evaporator/condenser 14 (depending on whether the heat pump is being used to heat up or cool down the cargo space) and out through the first air outlet 7.

The heat pump 4 is also provided with a second air inlet 9 and a second air outlet 10 which are both open to the interior of the cargo space. The positioning of this second air inlet 9 and second air outlet 10 in the figure is purely illustrative and optimal positioning will be within the capabilities of the skilled person. The arrows indicating the direction of the second air flow 11, wherein the second air flow 11 goes from the top of the cargo space to the bottom, also indicate just one possibility among many. The present configuration may be advantageous for more evenly distributed heating, as hotter air rises, and thus the aspirated air will be relatively cold. Other configurations may be more advantageous in other circumstances, as the skilled person will be capable of establishing. A configuration wherein the second air inlet 9 and the second air outlet 10 are embodied as concentric tubes is also a possibility, for example. Also, in the depicted embodiment the second air inlet 9 and second air outlet 10 stick out from the heat pump, but this is not always necessary or even advantageous, as will be discussed further on.

The second air inlet 9 and second air outlet 10 are be provided with fans or other means of displacing air (not depicted), for routing the second air flow 11 from the second air inlet 9 past the second condenser/evaporator 15 (depending on whether the heat pump is being used to heat up or cool down the cargo space) and out through the second air outlet 10.

In effect, to install the heat pump 4 in a cargo space, only very few adaptations need to be made to the cargo space unit: a means for connecting the heat pump 4 electrically to the vehicle battery 21 is needed, at least one (in most cases two) holes need to be made in the wall of the cargo space unit 1 to accommodate the first air inlet 6 and the first air outlet 7, and - unless it was already present, which it may be in several types of cargo spaces 1 - insulation 5 should be provided. Furthermore, the heat pump 4 will in most cases need to be (detachably) attached to the cargo space, which can be done in several straightforward ways (e.g. by means of fastening strips, bolts, etc.) which any skilled person will be able to realize and which need not be very invasive.

Fastening means which make it relatively straightforward to remove the heat pump from the cargo space, either for maintenance or to transfer the heat pump to a different cargo space, are preferred. Referring to figures 4-6, in a further embodiment, the heat pump 4 may comprise a housing 22 (for instance in the shape of a parallelepiped) which can be easily positioned in and attached to a support frame 23 mounted to the floor 25 of the cargo space 1. The support frame 23 comprises an upright frame element 26 provided with one or more ventilation openings 28. At the inner circumference of the upright frame element 26 a flange 27 is formed that may carry the bottom of the housing 22 of the heat pump 4. When the housing is positioned on this flange 27 a small air gap is still present between the bottom side of the housing 22 and the top side of the floor 25. The air gap covers a predefined height or distance, typically between 1 cm and 10 cm. The air gap together with the air opening 28 allows for air from the cargo space to enter the heat pump via the air inlet 32. next to the air inlet 32 a stub 30 of the ambient air inlet 30 of the heat pump 4 is arranged allowing attachment of a tube arranged to extend through the floor to provide access to the heat pump. At the top side of the housing a stub 33 for the heated or cooled air to be guided into the cargo space and a stub 31 a stub for connecting of a tube to a position outside the cargo space are arranged. To the stub 33 an air outlet unit 35 can be mounted. The air outlet unit 35 comprises a upright channel 36 leading the cooled or heated air upwards, for instance to a position right beneath the ceiling of the cargo space. The upright channel 36 connects to a generally U-shaped set of channels leading to air to several position along the length and width of the cargo space. The set of channels comprises a distribution channel 37 configured to distribute the air over a first air guide 38 and a second air guide 39. Both air guides 37, 38 extend in a generally longitudinal direction, for instance from a position at the front of the cargo space to a second position at the back of the cargo space. At the lower side of each of the air guides 38, 39 one or more ventilation openings (grids) 40 are provided in order to guide the air at different longitudinal (and transversal) positions downwards into the cargo space. In this manner the conditioned air can be more evenly distributed over the entire cargo space, also in cases wherein the cargo space has been loaded (since the risk of obstruction of the air flow by the load is restricted).

Notably, the installation of this heat pump 4 into the cargo space of a vehicle is usually much easier than the installation of existing heating systems, which has as a consequence that the heat pump is also much easier to remove from the cargo space than existing systems. The heat pump may then be installed into the cargo space of a new vehicle, which is too onerous for many of the existing systems. As the heat pump may have a lifetime longer than a heavily used vehicle used for transport, this has obvious advantages when it comes to cost as well as sustainability.

While some vehicles include cargo spaces, other vehicles are designed for a cargo space to be easily attachable and removable from them. A cargo space which may be attached to such a vehicle is depicted in Fig 2. In this figure, the details of the heat pump 4 have been depicted in more detail - it is in principle the same type of heat pump 4 as can also be seen in Fig. 1.

Depicted in the figure are the first air inlet 6, the first air outlet 7, and a first

evaporator/condenser 14 (depending on whether the heat pump is configured to heat up or cool down the cargo space) in between. Also depicted are the second air inlet 9, the second air outlet 10, and a second condenser/evaporator 15 (depending on whether the heat pump is configured to heat up or cool down the cargo space) in between. A flow circuit for the working fluid 12 is also depicted: the fluid flows between both evaporator/condensers 14, 15, through a compressor 13, and through an expansion valve 16.

In the depicted embodiment, the second air inlet 9 and the second air outlet 10 are simply openings in the heat pump 4 (or respective stubs 31, 31) to the outside. Tubing may be attached to it, but this tubing is not necessary, and may in some cases advantageously not be present. In embodiments of the invention, for instance the embodiment with the air outlet unit 35 shown in figures 3-5, the tubing is provided to improve the even distribution of the conditioned air over the cargo space in order to increase the homogeneity of the temperature inside the cargo space. The use of tubing and therefore the changing (and/or increasing the number of) the air discharge positions may reduce the temperature differences inside the cargo space.

Fans 20 are depicted behind the evaporator/condensers. This may help the efficiency of the heat pump 4, especially in the evaporation stage. Energy to power these fans may be provided by the battery 21of the vehicle. A control unit (not depicted) may switch on and switch off these fans 20 independently from one another as needed.

The control unit may also control other parameters of the heat pump 4, including the flow velocity of the first air flow 8 and the second air flow 11 (for instance through controlling the fans or other means of displaying air which may be present at the first air inlet 6, the first air outlet 7, the second air inlet 9 and the second air outlet 20), the flow velocity of the working fluid 12, and the compression strength exerted at the compressor 13. In case the heat pump is a reversible heat pump, the control unit may be configured to allow reversal of the flow direction of the working fluid 12 in order to change the function of the heat pump 4 between heating up and cooling down the cargo space, or whether to defrost the evaporators/condensers 14, 15 as needed. In other embodiments the control unit only switches on or off the heat pump and the above-mentioned other parameters including the flow velocity, are kept constant. In further embodiments wherein the cargo unit comprise two heat pumps, the first heat pump may be optimized for cooling air while the other heat pump may be optimized for heating air. The control unit is configured to switch on the first heat pump and switch off the second heat pump in order to heat the air in the cargo space and to switch off the first heat pump and switch on the second heat pump in order to cool the air in the cargo space. No reversal of the flow direction of any of the working fluids needs to occur.

Figure 3 depicts an embodiment of the heat pump 4 according to invention, showcasing how relatively compact the heat pump 4 may be. A relatively small size of the heat pump 4 is desirable as the volume of the heat pump 4 may be seen as lost volume of cargo space.

In the figure we can see two of the air inlets and/or outlets 6, 7, 9, 10, wherein the left opening 17 in the figure will be either the first inlet 6 or the first outlet 7 for the first air flow 8 and the right opening 18 in the figure will be either the second inlet 9 or the second outlet 10 for the second air flow 11. The first and second condenser/evaporator 14, 15 can also be seen - in use, the front will be covered by the panel 19 also seen in the figure.

If the difference between the outside temperature and the desired temperature of the cargo space is small, a generic heat pump 4 may be sufficient to heat up the cargo space to the desired temperature. For example, if the desired temperature is "room temperature" (generally put at about 20° Celsius), many existing heat pumps will be able to heat the cargo space to this temperature for an outside temperature in the 10-20°C range. For example, some cargo spaces units may be equipped with air conditioning modules, which comprise a heat pump primarily meant to cool down the cargo space. Such a heat pump in an air conditioner may have the capability of reversing the flow of working fluid, primarily in order to defrost the evaporator when needed. Reversing such a heat pump for heating the cargo space may be possible, but in most cases this will only be effective in fairly temperate outside circumstances.

However, coefficients of performances (COP) for most existing heat pumps decrease steeply especially if the outside temperature is negative (i.e. < 0° C), as these heat pumps have not been optimized for such circumstances.

In embodiments of the present disclosure, a heat pump 4 is used which may have a COP of at least 1.5, for instance a COP of about 2, even for temperatures as low as -20°C, which means that the IkW of energy from the vehicle battery is used for to produce 2kW of "heating power". In practice, this means that the first air inlet 6 may let in air at approximately -20°C, and this first air flow 8 when it is ejected from the vehicle through the first air outlet 7 may have an even lower temperature, for instance a temperature of about -30°C or even -40°C. This makes it possible to maintain the interior of the cargo space at room temperature, as long as a sufficiently thick insulation layer 5 (for example an insulation layer of 3-6 cm) is present.

This COP of about 2 at -20°C may be achieved by optimizing certain factors.

For instance, a first factor which may be optimized is the stroke volume of the compressor 13. In particular, the control unit should be able to adapt this stroke volume according to the available energy supply and the outside and inside temperatures. For instance: if the outside temperature rises, the stroke volume of the compressor should be lowered to ensure that not too much energy is used from the battery 2.

Secondly, a judicious choice of working fluid 12 may enable a higher COP to the used. Properties of the working fluid which are important for this are its phase boundaries at various pressures. A suitable working fluid is for instance a refrigerant of the R404 type (according to ASHRAE designated number, i.e. 44+2% C ₂ HF ₅ · 52+1% C ₂ H ₃ F ₃ · 4+2% C ₂ H ₂ F ₄ ), though the skilled person will be able tot find other suitable options.

Thirdly, the size of the heat pump 4 and in particular the size of the evaporator 14 is important. A balance should be found here: a too small evaporator will not be capable of extracting heat from very cold outside air, but a too large heat pump 4 will take away too much valuable cargo space.

By optimizing the above three factors, it has been found to be possible to achieve a COP of 2 even at temperatures of -20° Celsius, thus making it possible to heat up a cargo space to room temperature even with outside air at -20° Celsius, using only the IkW produced by the battery 2 of the vehicle.

A further advantage of this heater is that the heat pump 4 is fully reversible. The skilled person will be able to achieve this, through the reversal of the direction of the flow of working fluid 12 (for instance through the use of various valves and pumps). The reversibility has a consequence that the cargo space can be kept at room temperature not only with outside temperatures ranging from -20°C to +20°C, but also for temperatures above that, up to 40°C or in some cases even more. A single heat pump 4 may in this way provide both heating and cooling, and allow for the transport of goods which need to be kept at room temperature (or another temperature) through a great variety of outside circumstances.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the scope of the appended claims.