COOLING SYSTEM AND A PANEL MODULE FOR A COOLING SYSTEM

The invention relates a cooling system comprising one or more cooling circuits and one or more heat sink circuits, wherein the heat sink circuits are placed in the ground and/or immersed into water.

The present invention further relates to a panel module for mounting onto an existing internal structure of a building, which panel module is suitable for being integrated in a cooling system.

Description of the related art

There are principally three known forms of cooling, namely compressor cooling, absorption cooling and cooling by means of semiconductors. The compressor cooling is known for instance from ordinary refrigerators and air conditioning systems, in which a compressor is inserted in a cooling circuit along with a condenser and a throttle valve. The absorption cooling is known from cooling systems for instance for buildings, where a heat source is used in connection with a heat pump, whereby cooling can be obtained from the system. Cooling by means of semiconductors is known for instance from cool boxes, where an electric current is passed through an element, whereby one side of the element becomes cold (e.g. Peltier elements).

A disadvantage of compressor cooling and absorption cooling is that refrigerants, such as for instance NH ₃ , CO ₂ , R134A and H ₂ O/LiBr, are needed. Most of these refrigerants are either synthetic, toxic, expensive and difficult to produce or not biodegradable.

With the present attention directed towards energy related and environmental matters, it is of great importance that the emission of CO ₂ is reduced as much as possible. That means that the relationship between the energy consumption and the obtained cooling effect is an important parameter to control. Therefore, the high

energy consumption related to the known cooling principles is a great disadvantage of the cooling systems known in the art:

- In compressor cooling, which is at present the cheapest known form of cooling, electricity is used for operating the compressor.

- hi absorption cooling, heat energy is used for operating a cooling circuit. It is estimated that about three times more energy is needed for obtaining the same cooling effect by absorption cooling when compared to compressor cooling.

- In cooling by means of semiconductors, electricity is used for obtaining the cooling effect. It is estimated that about ten times more energy is needed for obtaining the same cooling effect by cooling by means of semiconductors when compared to compressor cooling.

A third disadvantage of compressor cooling is that a compressor emits a certain amount of noise during operation and induces vibrations when repeatedly being started and stopped.

A fourth disadvantage of these forms of cooling is that condensation may appear on the surfaces of the cooling elements due to the fact that they are sometimes cooled below the dew point of the air within the room. Hereby the humidity of the air is reduced, which can be unpleasant for the people staying within the room.

A fifth disadvantage is that is can be difficult to control such systems accurately, since for instance compressor cooling includes repeated starts and stops of the compressor, making the actual temperature fluctuate up and down around the desired temperature.

An object of the present invention is to provide a cooling system that eliminates or at least reduces the above-mentioned disadvantages of the known systems significantly.

Brief description of the invention

The present invention relates to a panel module for mounting onto an existing internal structure of a building so as to form an internal surface within a room to be cooled, the panel module comprising a passageway for a cooling fluid, a fluid inlet to the passageway, a fluid outlet from the passageway and an outer cooling surface to be faced towards the room to be cooled, arranged so that cooling fluid passing through the passageway will be in close thermal contact with the cooling surface and will be able to absorb heat energy from the room to be cooled and transport away the heat energy. Such a panel module is suitable for being integrated in the cooling circuit of a cooling system, which enables construction of very flexible and customized cooling systems, even when the cooling system is installed in an already existing room or building.

In an embodiment of the invention, the cooling surface comprises a sheet of a heat- conducting material, such as aluminium, covering at least a part of the front side of the panel module. Letting the cooling surface comprise a sheet of a heat-conducting material increases the cooling effect of the panel module when being part of a cooling circuit of a cooling system.

In an embodiment of the invention, the cooling surface comprises a number of through-holes for improving the acoustic properties of the panel module. The provision of holes through the cooling surface to one or more cavities and/or a sound attenuating material behind the cooling surface significantly improves the acoustic properties of the panel modules when mounted, for instance, under the ceiling of a room.

In an embodiment of the invention, the passageway is formed between the cooling surface and a module core structure fixed to the backside of the cooling surface. This is an advantageous way of forming the passageway in that the cooling fluid passing

through the passageway will be in direct physical contact with the cooling surface, the latter forming a part of the wall of the passageway.

In a further embodiment of the invention, the module core structure is made from a plastic material. The use of a commonly available plastic material is advantageous in that it can be relatively non-expensive and easy to process and work with.

In an embodiment of the invention, the maximum width of the passageway is between 2 cm and 12 cm, preferably between 5 cm and 9 cm. Choosing the maximum width of the passageway to fall within these ranges has shown to provide the panel module with a very high cooling capacity.

In an embodiment of the invention, the maximum height of the passageway is between 0.3 cm and 5 cm, preferably between 1 cm and 3 cm. Choosing the maximum height of the passageway to fall within these ranges enables for creation of a suitable cavity behind the panel module to be used for several different purposes.

In an embodiment of the invention, the passageway is divided into at least two paths surrounding a central area of the cooling surface and leaving free a border area along at least one side of the panel module. The use of such a passageway pattern has shown to give a very efficient pattern of convection along the cooling surface improving the cooling capacity of the panel module.

In an embodiment of the invention, the panel module comprises a slab of a heat- insulating material, arranged so that the passageway is situated between the cooling surface and the slab, preferably in the form of a hose placed in one or more recesses formed in the slab for conducting cooling fluid from the fluid inlet to the fluid outlet, means for thermally coupling the passageway and the cooling surface, such as a heat- conducting paste, and cavities aligned with the through-holes of the cooling surface. This is another embodiment of the panel module, which has also demonstrated very good cooling capacities.

In an embodiment of the invention, the panel module comprises liquid coupling means arranged for coupling the fluid inlet and the fluid outlet to the fluid outlet and fluid inlet, respectively, of a similar panel module. The possibility of coupling panel modules together in series enables construction of cooling circuits of arbitrary sizes and shapes from a number of standardized panel modules.

hi an embodiment of the invention, the mass of the panel module per unit area of the outer cooling surface is in the range of 3 kg/m ² to 10 kg/m ² , preferably in the range of 5 kg/m ² to 8 kg/m ² . Keeping the mass per unit area of the panel module within this range facilitates the mounting of the panel modules, which will be significantly lighter than conventional panel modules for being mounted, for instance, under the ceiling of a room.

In an embodiment of the invention, the amount of cooling fluid that may be contained within the passageway of the module per unit area of the outer cooling surface is in the range of 0.5 litres/m ² to 1.2 litres/m ² , preferably in the range of 0.7 litres/m ² to 1.0 litres/m ² . Keeping the amount of cooling fluid within this range has been found to assure a suitable cooling effect of the panel module when being part of a cooling circuit of a cooling system.

hi an embodiment of the invention, the area of the outer cooling surface is in the range of 0.06 m ² to 6 m ² , typically in the range of 0.2 m ² to 3 m ² . Keeping the area of the outer cooling surface within this range assures that the panel modules are of a size that can be handled and mounted by a single person.

hi an aspect of the invention, it relates to a cooling system comprising one or more cooling circuits, each comprising one or more cooling elements, one or more circulating pumps, one or more heat sink circuits and a cooling liquid, wherein the one or more heat sink circuits are placed in the ground and/or immersed into water and coupled to the one or more cooling circuits allowing the same cooling liquid to

be circulated in its liquid phase through the one or more cooling circuits including the one or more cooling elements and through the one or more heat sink circuits, and at least one of the cooling elements is integrated in one or more panels mounted onto an existing internal structure of a building so as to form an internal surface within a room to be cooled. Integrating at least one of the cooling elements in a panel enables construction of very flexible and customized cooling systems, even when the cooling system is installed in an already existing room or building.

In an embodiment of the invention, the internal surface includes a ceiling of the room to be cooled. Cooling the ceiling of the room gives a uniform temperature distribution within the room to be cooled without the annoying draughts most often accompanying the mechanical circulation of air induced by a conventional air conditioning system.

In an embodiment of the invention, the panels each comprises a cooling surface facing the room to be cooled and a layer of a heat-insulating material situated between the cooling surface and the internal structure of the building. By placing a layer of a heat-insulating material situated between the cooling surface and the internal structure of the building, it is achieved that the panel contributes to the thermal insulation of the room.

In an embodiment of the invention, the one or more panels are modular in construction. The use of modular panels enables construction of cooling circuits of arbitrary sizes and shapes from a number of standardized panel modules.

In an embodiment of the invention, the one or more panels comprise one or more panel modules as described above.

hi an embodiment of the invention, the cooling liquid is pure water. Using pure water as refrigerant is advantageous in that it contains no substances that are either synthetic, toxic, expensive and difficult to produce or not biodegradable. The use of

water is possible, since the cooling by means of the cooling elements typically takes place in the temperature range between 0°C and 20 °C, preferably between 5 °C and 15 °C.

In an embodiment of the invention, at least one of the one or more cooling circuits comprises one or more valves for enabling and disabling the flow of cooling liquid through the cooling circuit. The use of valves for enabling and disabling the flow of cooling liquid through a cooling circuit makes it possible to control the flow of cooling liquid through the cooling circuit and, thereby, the temperature in the rooms to be cooled very accurately. Also, the use of valves for enabling and disabling the flow of cooling liquid through a given cooling circuit makes it possible to obtain different temperatures in the rooms cooled by different cooling circuits belonging to the same cooling system.

In an embodiment of the invention, at least one of the one or more cooling circuits comprises one or more valves for enabling and disabling the mixture of heated cooling liquid returning from one or more cooling elements into cooled cooling liquid returning from the one or more heat sink circuits. Enabling the mixture of heated cooling liquid returning from one or more cooling elements into cooled cooling liquid returning from the one or more heat sink circuits makes it possible to raise the temperature of the cooling liquid circulating in a cooling circuit to a temperature above the dew point of the air in the room to be cooled, when this is necessary in order to avoid condensation on the cooling surfaces of the cooling circuit.

In an embodiment of the invention, the one or more circulating pumps and the one or more valves are connected to a control unit comprising one or more temperature sensors and one or more humidity sensors, the control unit being arranged to control the temperature of the cooling liquid flowing through the one or more cooling circuits in dependency of a temperature and humidity of the air within a room to be cooled so as to avoid condensing of the humidity of the air onto a cooling surface of

the one or more cooling elements. The use of temperature and humidity sensors along with a control unit enables automatic control of the temperatures in one or more rooms cooled by one or more cooling circuits.

In an embodiment of the invention, at least one of the one or more cooling circuits comprises a reservoir. The use of a reservoir makes it possible to keep a certain buffer of cooling liquid, which can, for instance, be used for a fine tuning of the temperature through a bypass connection.

In an embodiment of the invention, at least one of the one or more cooling elements is integrated in a cabinet unit. The integration of one or more cooling elements in a cabinet unit enables the cooling system to be used for providing a uniform cooling of wine bottles or other items for whom the storage temperature is critical. The cooling elements may be placed in the shelves/dividers, in the sides and/or in the top/bottom of the cabinet unit.

In an embodiment of the invention, at least one of the one or more cooling elements is integrated in a structural part of a building. Integrating one or more cooling elements in a structural part of a building enables uniform cooling of the building or rooms therein.

In an embodiment of the invention, the one or more cooling elements comprise one or more of the following: a cooling surface, a cooling coil and/or a cooling radiator. Cooling surfaces, cooling coils and cooling radiators are all well-proven and efficient cooling elements.

In an embodiment of the invention, at least one of the one or more cooling elements is integrated in a machine unit. Integrating one or more cooling elements in a machine unit enables the use of the cooling system in connection with for instance a fan coil and/or a heat exchanger unit. A large scale cooling system with cooling elements integrated in a machine unit can be used for cooling buildings, cool storage

rooms, sports facilities, technique facilities and the like, while smaller scale systems can be used for cooling industrial machines of any kind and (in very small scale) electronics and computers etc.

In an embodiment of the invention, at least one of the one or more cooling circuits is connected to a heating system through a heat pump. Connecting one or more cooling circuits to a heating system through a heat pump for instance enables the use of heat energy acquired by cooling circuit in one room to be re-used for heating another room.

In an aspect of the invention, it relates to a building comprising a cooling system as described above.

In an aspect of the invention, it relates to a method for establishing a deep ground loop into the ground, comprising the steps of: drilling a bore into the ground, filling up the bore with a sludge containing clay, such as bentonite, and pushing a closed end of a flexible hose loop towards the bottom of the drilled bore, so that the closed end of the loop is situated in a depth between 8 meters and 100 meters below the surface. By using this method, it is achieved that the deep ground loop can be established with a minimum impact area at the surface of the ground.

In an embodiment of the invention, the step of drilling a bore is preceded by a step of establishing a base cavity in the ground from which the following steps are being performed. The use of a base cavity enables hiding of the connections between the deep ground loop and the rest of the cooling system under the ground surface, when the deep ground loop has been established and the base cavity may have been partly or completely filled up again.

In a further embodiment of the invention, the depth and the width of the base cavity are between 0.5 meters and 2 meters. The use of a base cavity of these dimensions

has shown to be sufficient for establishing one or more deep ground loops according to this method.

In an embodiment of the invention, the diameter of the bore is between 5 cm and 50 cm, preferably between 15 cm and 35 cm. A bore of such dimensions have shown to be advantageous in the establishment of deep ground bores according to this method.

In an embodiment of the invention, the step of drilling the bore and the step of filling up the bore are being performed simultaneously. Performing these two steps simultaneously makes sure that the bore is properly filled with the sludge, and at the same time, it saves time.

In an embodiment of the invention, the closed end of the hose loop is formed by connecting two hose parts by a U-shaped pipe, preferably made from a hard material, such as stainless steel. Using a U-shaped pipe made from a hard material ensures that the hose loop is not being compressed at its closed end while being pushed towards the bottom of the drilled bore.

In an embodiment of the invention, the step of pushing a closed end of a hose loop towards the bottom of the drilled hole includes the use of a fork-shaped pushing device engaging the closed end of the loop. The use of a fork-shaped pushing device ensures a safe and stable engagement between the pushing device and the hose loop being pushed towards the bottom of the drilled bore.

In an embodiment of the invention, the closed end of the hose loop is covered by a torpedo-shaped shell, preferably made from a metal, when being pushed towards the bottom of the drilled bore. Covering the closed end of the hose loop by a torpedo- shaped shell facilitates the motion of the hose loop down through the drilled bore and at the same time protects the closed end of the hose loop from impacts caused by the rocks and other hard items that may be found at the edge of the bore.

In an embodiment of the invention, the drilled bore is inclined between 0° and 90°, preferably between 15° and 75°, most preferably between 30° and 60°, with respect to the vertical direction. Inclining the drilled bore enables the drilling of more than one bore from the same base cavity. Also, it facilitates the use of some types of drilling machines which can only hardly be operated in a vertical mode.

In an embodiment of the invention, more than one bore is being drilled from the same base cavity. Drilling more than one bore from the same base cavity facilitates the coupling of two or more deep ground loops (typically in parallel) for obtaining a better cooling effect of the heat sink circuit.

In a further embodiment of the invention, the angle between two neighbouring bores as seen from a position vertically above the base cavity is at least 15°. Making sure that the angle between neighbouring bores as seen from the above is at least 15° ensures that the distance between the two bores is large enough to obtain optimum cooling of the cooling liquid circulating in both of the deep ground loops.

In an aspect of the invention, it relates to a method for installing a cooling system in a building, comprising the steps of: placing in the ground and/or immersing into water one or more heat sink circuits, mounting onto an existing internal structure of a building one or more panels comprising one or more cooling elements, establishing one or more cooling circuits comprising the one or more cooling elements, and coupling the one or more heat sink circuits to the one or more cooling circuits allowing the same cooling liquid to be circulated in its liquid phase through the one or more cooling circuits including the one or more cooling elements and through the one or more heat sink circuits. A cooling system installed according to this method has shown to be very advantageous in relation to energy consumption as well as noise level and temperature stability when compared to other cooling systems known from the art.

In an embodiment of the invention, the cooling system is a cooling system as described above.

In an embodiment of the invention, the step of placing in the ground and/or immersing into water one or more heat sink circuits includes placing a part of the one or more heat sink circuits in a depth between 8 meters and 100 meters below the surface. Placing parts of the one or more heat sink circuits in this depth assures a uniform and stable temperature of the cooling liquid returning from the heat sink circuits independently of the time of year and the climatic conditions at the surface of the ground.

In an embodiment of the invention, the one or more heat sink circuits comprise one or more deep ground loops of hoses, which are placed deep into the ground by means of the method described above.

hi an embodiment of the invention, the step of mounting one or more panels, includes mounting one or more panel modules as described above.

The drawings

In the following, a few embodiments of the invention are described and explained in more detail with reference to the drawings, where

fig. 1 illustrates a schematic view of a first embodiment of a cooling system according to the invention,

fig. 2 illustrates the relationship between ground depth and the minimum and maximum soil temperatures in Denmark,

fig. 3 illustrates a schematic cross-sectional view of a base cavity with two drilled ground bores according to an embodiment of the invention,

fig. 4 illustrates a schematic view as seen from above of a base cavity with eight drilled ground bores according to an embodiment of the invention,

fig. 5 illustrates a schematic view of a second embodiment of a cooling system according to the invention,

fig. 6a illustrates the module core structure of a panel module according to a first embodiment of the invention as seen from the back side,

fig. 6b illustrates a cross-section of the same module core structure along line A very close to the edge of the structure as indicated in fig. 6a,

fig. 6c illustrates a cross-section of the same module core structure along line B closer to the centre of the structure as indicated in fig. 6a,

fig. 7a illustrates a cover plate for a panel module according to the first embodiment of the invention as seen from the front,

fig. 7b illustrates the same cover plate as seen from the side,

fig. 8a illustrates an assembled panel module according to the first embodiment of the invention as seen from the front,

fig. 8b illustrates the same assembled panel module as seen from the side,

fig. 9a illustrates the internal structure of a panel module according to a second embodiment of the invention as seen from the front,

fig. 9b illustrates the same internal structure as seen from the side,

fig. 10a illustrates a cover plate for a panel module according to the second embodiment of the invention as seen from the front,

fig. 10b illustrates the same cover plate as seen from the side,

fig. 11a illustrates an assembled panel module according to the second embodiment of the invention as seen from the front, and

fig. l ib illustrates the same assembled panel module as seen from the side.

Detailed description

Fig. 1 illustrates a schematic view of a first embodiment of a cooling system 1 according to the invention, comprising a cooling circuit 2, which cooling circuit 2 comprises a number of cooling elements 3 situated in the ceiling 4 of a room 5 in a building. The cooling system 1 further comprises a cooling hose 6, which is placed within the ground 7 forming a ground loop (se fig. 2) indicated by the two arrows.

The cooling circuit 2 and the cooling hose 6 are coupled to each other forming together a common closed loop in which a cooling liquid (not shown) circulates during operation of the cooling system 1. This circulation is obtained by means of a circulating pump 10, which is placed in one of the coupling points between the cooling hose 6 and the cooling circuit 2. The absence of an evaporator and a condenser in the cooling system 1 emphasizes that according to the invention, no phase transitions of the cooling liquid takes place and, thus, the cooling liquid is in its liquid phase at all times and at all places within the cooling system 1.

During passage through the ground loop, the cooling liquid inside the cooling hose 6 will give off excess heat energy to the surrounding ground 7 and end up being in thermal equilibrium with the ground 7, meaning that the cooling liquid will get the same temperature as the surrounding ground 7.

When the cooling liquid has been cooled down to ground temperature in the ground loop, it is circulated within the cooling circuit 2 by means of the circulating pump 10. The circulating pump 10 is controlled by a CPU (Central Processing Unit) 11 receiving control inputs from a temperature sensor 12 and a humidity sensor 13 situated in the room 5 to be cooled by the cooling system 1.

If the room temperature sensed by the temperature sensor 12 exceeds a preset desired room temperature, the CPU 11 will start the circulating pump 10, thus sending cooling liquid at ground temperature through the cooling elements 3 of the cooling circuit 2. The cooling elements 3 are designed to assure a good thermal connection between the cooling liquid circulated therein and the air in the room 5 to be cooled, so that the air inside the room 5 is cooled down when cold cooling liquid is circulated within the cooling elements 3. As soon as the temperature has decreased to the desired value, the CPU 11 will stop the circulating pump 10 from sending further cold cooling liquid into the cooling circuit 2.

The humidity sensor 13 is used for avoiding condensing of humidity from the air onto the surfaces of the cooling elements 3. The actual dew point is calculated from the actual air humidity within the room 5, and it is assured that the cooling liquid circulating within the cooling circuit 2 of the room 5 always has a temperature above this calculated dew point. This can be achieved in several ways, for instance by heating the cooling liquid before letting it enter the cooling circuit 2 or, more preferably, by using a valve system (not shown) for mixing some of the warmer cooling liquid leaving the cooling circuit 2 with the colder cooling liquid entering the cooling circuit 2.

A system as described above can be operated with a very small temperature hysteresis compared to conventional air-conditioning systems, which typically cannot stand being switched on and off several times per minute. This means that a very constant temperature can be obtained. The temperature hysteresis of the present

system has been measured to be 0.1-0.2° C, whereas temperature hystereses of conventional cooling systems typically are about 2° C.

Furthermore, the well-known inconvenience of draught connected to conventional air-conditioning systems is avoided, as are the problems of dehydration and of varying temperatures in different parts of the room 5, and the system is practically noiseless in operation.

An even further advantage of the present invention as compared to conventional air- conditioning systems is the amount of energy used to operate the system. Tests have shown that a "wine cellar" in the form of a walk-in wine storage cabinet for approximately 1000 bottles constructed inside the serving room of a restaurant can be kept at a constant temperature of 15° C when the room temperature in the surrounding room is 20-22° C using a circulating pump 10 that consumes only 5 W of power when it is running, which is approximately half of the time. Calculations have shown that for a large-scale system (more specifically the air-conditioning system in a local bank covering 500 m ² of office landscape), the yearly power consumption could be reduced from approximately 170,000 kWh to 170 kWh, i.e. by a factor of 1000 (one thousand!), by replacing the existing conventional system with a cooling system 1 according to the present invention.

In the embodiment of the cooling system 1 illustrated in fig. 1, the type of ground loop used for cooling the cooling liquid is not indicated. Fig. 2 illustrates the relationship between depth in the ground 7 and the minimum and maximum soil temperatures in Denmark. In some embodiments of the present invention, a horizontal ground loop 19 with the cooling hose 6 forming a serpentine pattern, just like the ones usually used in ground heating systems, may be used. In order to reduce the cumbersome work of digging when burying such a horizontal ground loop 19, it is normally placed just deep enough within the ground 7 to ensure that the surrounding soil will not be freezing during the winter season.

In this depth, the temperature of the soil surrounding the horizontal ground loop 19 varies with the time of the year in most geographical places, hi Denmark, for instance, a horizontal ground loop 19 in a depth of approximately 1 meter is surrounded by soil, whose temperature is just above the freezing point in the winter time but may increase to about 17-18° in the summer time. This means that in winter, when cooling is seldom needed, the cooling liquid will be cooled down to only a few degrees Celsius during passage through the horizontal ground loop 19, thus achieving a very good cooling capacity, whereas in summer, when the cooling is most needed, the temperature of the cooling liquid returning from the horizontal ground loop 19 will be only a few degrees below the temperature usually desired inside a room 5 to be cooled, and the cooling capacity of the cooling liquid is rather limited.

Contrary to that, when using a deep ground loop 8 having its closed end 9 situated deeply within the ground 7, a constant temperature of the cooling liquid can be obtained all around the yean due to the fact that in the deeper layers of the ground 7, the temperature is constant, hi Denmark, for instance, beneath a depth of approximately 10 meters, the ground temperature is constantly 8° C. This means that by insulating the upper part of the deep ground loop down to a depth of 10 meters, a deep ground loop 8 can be obtained that will always return cooling liquid at 8° C given that the length of the deep ground loop 8 is sufficient for the cooling liquid to obtain thermal equilibrium with the surrounding ground 7.

The optimum length of the deep ground loop 8 depends on the desired cooling capacity of the cooling system 1 and the angle of the deep ground loop 8 with relation to the vertical direction. In Denmark, the operational depth (where the temperature is constantly 8° C) is between 8 m and 100 m, corresponding to a total length of the cooling hose 6 within the deep ground loop 8 of between 16 m and several hundred meters.

It follows from the above-described differences between horizontal ground loops 19 and deep ground loops 8 that the latter comprises several advantages as compared to the former: Firstly, a constant and relatively low temperature of the cooling liquid returning from the deep ground loop 8 assures simple control and good cooling capacity of the cooling system 1, also in the summer time when it is most needed. Secondly, due to the fact that in a deep ground loop 8, which is insulated near the surface of the ground 7, the cooling liquid will never be exposed to temperatures below 8° C, pure tap water can be used as cooling liquid, whereas in a horizontal ground loop 19, the cooling liquid will be exposed to temperatures very close to the freezing point and, in order to be sure to avoid freezing of the cooling liquid, antifreeze additives, such as ethylene glycol must be added, if water is to be used as cooling liquid. Such additives are typically rather toxic, and harsh safety precautions must be followed in order to keep them from polluting the environment.

A third advantage of the deep ground loop 8, which will be discussed further in relation to figs. 3 and 4 below, is that it only requires a relatively small opening in the ground surface to establish a deep ground loop 8, whereas a large area has to be dug up (sometimes a complete garden will be destroyed), when a horizontal ground 19 loop has to be established.

A fourth advantage is that the deep ground loop 8 will be able to supply water for a heat pump 36 in a geothermal heating system all year around. Typically, there is a temperature difference across a heat pump 36 of 3-5° C. hi Denmark, as can be seen from fig. 2, the wintertime temperatures of a fluid returning from a horizontal ground loop 19 can be close to the freezing point, leaving no room for a temperature difference of 3-5° C, whereas the temperature of a fluid returning from a deep ground loop 8 will be around 8° C all year round, leaving a safe margin to the freezing point of pure water with a temperature difference of 3-5 ° C.

Fig. 3 illustrates a schematic cross-sectional view of a base cavity 14 with two drilled ground bores 15, each containing a deep ground loop 8 according to an embodiment of the invention.

hi a preferred embodiment, the ground bores 15 are drilled with a diameter of 20 cm while at the same time being filled with a bentonite sludge 16. In principle, the ground bores 15 can be drilled in any angle with respect to the vertical direction, hi the shown embodiment, they have been drilled in a preferred angle of 45°.

The base cavity 14, from which the drilling of the ground bores 15 and the installation of the deep ground loops 8 are performed, need not be very large. In a test construction, a single deep ground loop 8 in a ground bore 15 with a diameter of 20 cm drilled at an angle of 45° was made from a base cavity 14 having a width of 1 m, a length of 1.5 m and a depth of 1.2 m. The limited demands for space within the base cavity 14 means that a deep ground loop 8 can be constructed in short time without severe damage to the area surrounding the building to be cooled. For the above-mentioned test construction, the deep ground loop 8 was installed under a paved parking lot, and the work was completed within four hours including the restoration of the pavement hiding the installation.

After completion of the drilling of the ground bores 15 to the desired length and depth, a deep ground loop 8 has been installed in each of the ground bores 15 by pushing the closed end 9 of a hose loop towards the bottom of the ground bore 15. The hose loop was pushed into and down through the ground bore 15 by means of a fork-shaped pushing device engaging the closed end 9 of the loop, hi order to avoid damage to the cooling hose 6 forming the deep ground loop 8 during the pushing, the closed end 9 was formed by connecting two parts of the cooling hose 6 by means of a U-shaped metal pipe 17. Further, in order to facilitate the motion of the motion of the hose loop down through the ground bore 15, the closed end 9 of the hose loop was covered by a torpedo-shaped metal shell (not shown) when being pushed towards the bottom of the ground bore 15.

As also indicated in fig. 3, the upper part (approximately 10 m) of each of the two parts of the cooling hose 6 forming the deep ground loop 8 is surrounded by a layer of a thermally insulating material 17 in order to avoid freezing of the cooling liquid within the cooling hose 6 in the winter time and heating of the cooling liquid by the surrounding upper layers of the ground 7 in the summer time.

Fig. 4 illustrates a schematic view as seen from above of a base cavity 14 with eight drilled ground bores 15 according to an embodiment of the invention. This shows how a number of ground bores 15 can be drilled from the same base cavity 14. With a minimum angle of 15° between two neighbouring ground bores 15, in principle up to 24 ground bores 15 and deep ground loops 8 can be constructed from the same base cavity 14, although it will require larger dimensions than the ones listed for the test configuration above. As it is seen in figs. 3 and 4, the individual ground bores 15 are preferably drilled at a certain angle with respect to the vertical direction. If more than a single ground bore 15 has to be drilled from a base cavity 14, making them all vertical would not only compromise the stability of the ground 7 beneath the base cavity 14. Also, the different deep ground loops 8 would be situated very close to each other in their full lengths, thus reducing the ability of the surrounding soil to absorb the heat energy from the cooling liquid inside the deep ground loops 8.

Fig. 5 illustrates a schematic view of a second exemplary embodiment of a cooling system according to the invention, in which three cooling circuits 2 conduct the cooling liquid to three rooms 20, 21, 22, respectively. In the first room 20, the cooling elements 3 are integrated in a number of ceiling panels 23 mounted on the ceiling 4 of the room 20. An embodiment of such ceiling panels 23 is described in detail below. In the second room 21, the cooling circuit 2 comprises a cooling element 3 in the form of a fan coil 24, whereas in the third room 22, the cooling elements 3 are integrated in a hanging ceiling 25, which may be constructed from ceiling panels 23 like the ones mounted on the ceiling 4 of the first room 20.

As can be seen from the figure, each of the cooling circuits 2 are controlled by an SPU (Slave Processing Unit) 26 receiving control inputs from a temperature sensor 12 and a humidity sensor 13 situated in the room 20, 21, 22 to be cooled. Each of the SPUs 26 is arranged to be able to open or close a circuit valve 27 in order to control the circulation of cooling liquid in the cooling circuit relating to the SPU 26.

If the room temperature in a given room 20, 21, 22 sensed by the respective temperature sensor 12 exceeds a preset desired room temperature, the corresponding SPU 26 will open its circuit valve 27, thus sending cooling liquid at ground temperature through the cooling elements 23, 24, 25 of the respective cooling circuit 2. As soon as the temperature has decreased to the desired value, the SPU 26 will close the valve 27 again to avoid sending further cold cooling liquid into the cooling circuit 2.

The humidity sensors 13 are used for avoiding condensing of humidity from the air onto the surfaces of the cooling elements 23, 24, 25. The actual dew point is calculated from the actual air humidity within the rooms 20, 21, 22 to be cooled, and it is assured that the cooling liquid circulating within the cooling circuits 2 does always have a temperature above this calculated dew point. In the shown embodiment, this is achieved by using a mixer valve 28 for mixing some of the warmer cooling liquid leaving the cooling circuits 2 with the colder cooling liquid entering the cooling circuits 2.

Each of the SPUs 26 communicates with a MPU (Master Processing Unit) 29, which controls the circulating pump 10, the mixer valve 28 and a main valve 30 as well as other central parts of the cooling system 1 in response to control signals from the SPUs 26 and a pressure monitor 31.

Figure 5 further illustrates that the MPU 29, the circulating pump 10, the mixer valve 28, the main valve 30 and the pressure monitor 31 may all be situated in a driver station 32 together with a water inlet 33, an air outlet 34 and an expansion tank 35.

In the embodiment shown the cooling liquid from the cooling circuits 2 pass through a heat pump 36 on its way back to the ground loop (indicated by the two arrows) to be cooled. The heat pump 36 uses some of the heat energy from the cooling liquid to heat up the heating liquid (not shown) of a conventional floor heating system 37 mounted within the floor 38 of the first room 20. In this way, the excess heat energy of the cooling liquid is used for a useful purpose instead of just being wasted in the ground 7.

Figs. 6a, 6b and 6c illustrate the module core structure 51 of a panel module assembly 49 according to a first exemplary embodiment of the invention. Please note that since fig. 6a illustrates the module core structure 51 as seen from the back side, whereas figs. 7a and 8a illustrate the cover plate 45 and the panel module 49, respectively, as seen from the front, the vertical orientation of figs. 6b and 6c is opposite to that of figs. 7b and 8b.

The module core structure 51 , which is shown from the back side in fig. 6a, basically consists of a frame-shaped plate made from a suitable plastic material. The most central part of the module core structure is an inner flat part 52, which surrounds a square aperture 55 in the centre of the module core structure 51.

Next to the inner flat part 52 are the inclined parts 53 of the module core structure 51 , which form together a triangular profile as illustrated in the cross-section of the module core structure 51 shown in fig. 6c. Just like the inner flat part 52, the triangular profile formed by the inclined parts 53 constitutes a square surrounding the central aperture 55 within the module core structure 51.

Outside the inclined parts 53 of the module core structure 51 is an outer flat part 54, constituting yet a square shape, although the outer flat part 54 is extended in each of the four corners forming the corner protrusions 56 of the module core structure 51, each of which comprises an elevated corner part 41 with a mounting hole 42 for

mounting the panel module assembly 49 onto a ceiling or another internal structure of a building with screws or the like (not shown). The elevation of the corner parts 41 is indicated in the cross-section of the module core structure 51 very close to the edge, which is shown in fig. 6b.

The inner 52 and outer flat parts 54 of the module core structure 51 are glued onto the back side of a cover plate 45 (see figs. 7a and 7b), whereby the triangular profile formed by the inclined parts 53 and the back side of the cover plate 45 together form a duct acting as a passageway (not shown) for the cooling fluid passing through the panel module assembly 49. This brings the cooling fluid in direct contact with the cover plate 45, which assures a very small temperature difference between the cooling fluid and the cooling surface (the front side of the cover plate 45) as well as a very short reaction time for the cooling surface to change temperature in response to a change of the temperature of the cooling fluid.

In each of the four corners, the triangular profile is provided with a fluid inlet/outlet 50 to which a piece of hose 57 can be connected in order to place the panel module assembly 49 in a serial relation with similar panel module assemblies 49. In order to assure the most efficient flow of cooling fluid through the passageway, such connection hoses 57 will be placed in two diagonally opposite corners of the panel module assembly 49 as illustrated in figs. 6a and 8a. However, the hoses 57 can also be placed in two corners next to each other, if it is necessary due to the geometry of the area covered by a number of panel module assemblies 49, in order to connect the panel module assemblies 49 in a serial relation. The two fluid inlets/outlets 50 that are not used for connecting the panel module assembly 49 to other panel module assemblies 49 can be blocked by means of a plug or the like (not shown).

The panel module is designed for a maximum speed of the cooling fluid of 2 m/s, corresponding to a flow of 350 litres/hour and a passage time per panel module of 3 seconds.

Figs. 7a and 7b illustrate a cover plate 45 according to an embodiment of the invention for the panel module 39 shown in figs. 6a, 6b and 6c as seen from the front and from the side, respectively.

The cover plate 45 is made in one piece from a plate of a heat conducting material, such as aluminium, comprising a front surface 46 acting as the cooling surface to be faced towards the room 5 to be cooled and four side flaps 47 covering the sides of the module core structure 51 except for the corner parts 41. The front surface 46 of the cover plate 45 is provided with a large number of holes 48 corresponding with a cavity behind the cover plate 45 for improving the acoustic properties, when the cover plate 45 is mounted on the module core structure 51.

Figs. 8a and 8b illustrates a panel module assembly 49 according to an embodiment of the invention comprising the module core structure 51 shown in figs. 6a, 6b and 6c and the cover plate 45 illustrated in figs. 7a and 7b.

In a square panel module assembly 49 of size 60 cm x 60 cm, the centre line of the duct formed by the inclined parts 53 of the module core structure 51 and the back side of the cover plate 45 will typically form a 40 cm x 40 cm square, and the central aperture 55 will be in the form of a 30 cm x 30 cm square. The height and the width of the duct will be 10 mm and 40 mm, respectively, leaving a cavity with a rectangular profile of dimensions of about 70 mm x 20 mm along the edge on all four sides of the panel module assembly 49.

The cover plate 45 will comprise about 300 throughíholes 48 placed in front of the central aperture 55 for improving the acoustic properties of the panel module assembly 49.

The fact that the cooling fluid is in contact with only some parts of the cover plate 45 causes an uneven temperature distribution across the cooling surface (the front side of the cover plate 45). For instance, measurements have shown corresponding values

of 10° C in the area, where the water is in contact with the cover plate 45, and 13.5° C at the centre of the cover plate 45. These temperature differences cause convection of the air along the cooling surface, which improves the cooling efficiency of the panel module assembly 49.

Advantageously, a plate of a conventional insulation material, such as rock wool or other kinds of mineral wool, can be mounted between the ceiling 4 or internal structure of the building and the panel module assembly 49. hi this way, the panel module assembly 49 will hide the insulation material, and the insulation material will improve the acoustic properties of the panel module assembly 49 providing the cavity behind the cover plate 45 with a soft back wall approximately 20 mm behind the cover plate 45.

The cavities along the edges of the panel module assembly 49 can be used for carrying electrical cables or the like, or they could be used for conducting the air of a ventilation system. The volume of the cavities would be sufficient for exchanging the air in a room at least once per two hours, and the cooling fluid passing through the duct could be used for cooling the incoming air on a warm summer day. Another possibility could be to use the panel module assembly as a heat exchanger recovering heat energy from the outgoing air to the incoming air through the cooling fluid passing through the duct.

If the water inlet 33 is connected to the public water supply, and some parts of the module core structure 51 are made from another type of plastic material with a significantly lower melting temperature than the rest of the structure 51 , the panel module assembly 49 could be used as a fire extinguisher. Upon the detection of a fire (based on temperature and air humidity measurements, possibly assisted by the use of smoke detectors), the parts made from the plastic material with the low melting point would melt and the controller 11 would open a valve to the public water supply and make the pump 10 increase the flow to its maximum. This would make water fall

as "rain" through the holes 48 in the cover plate 45 in sufficient amounts to extinguish fires of a certain magnitude.

Other functionalities that could be built into the panel module assemblies 49 include loud speakers placed in the central cavity behind the cover plate 45, power LEDs placed behind the holes 48 in the cover plate 45 to act as room lighting when they were on (and which would be practically invisible when they were off), motion detectors connected to alarm circuits and/or switching off the light and/or increasing the ventilation power (and, thus, the noise) when there were nobody in the room 5, and heating of the room 5 by sending a heating liquid through the panel module assemblies 49 instead of a cooling liquid.

Figs. 9a and 9b illustrate the internal structure of a panel module without a cover plate according to another embodiment of the invention as seen from the front and from the side, respectively.

A recess 40 for a passageway for cooling liquid (not shown) forms a serpentine path between two opposite corners 41 of the panel module 39. In each of the four corners 41, the height of the panel module 39 is reduced in relation to the height of the rest of the panel module 39. This makes room for connecting the fluid inlet (not shown) and the fluid outlet (not shown) of the passageway of the panel module to similar fluid outlets and inlets, respectively, of adjacent panel modules, and for mounting the panel module 39 onto a ceiling or another internal structure of a building with screws (not shown) through the mounting holes 42 placed in each corner 41 of the panel module 39.

Fig. 9a also illustrates a large number of cavities 43, the purpose of which is to improve the acoustic properties of the panel module 39 when mounted in a room of a building. Also shown is a recess 44 along each of the edges of the panel module 39 making room for electric wires etc., which can be retrofitted after mounting of the panel module 39.

Figs. 10a and 10b illustrate a cover plate 45 according to an embodiment of the invention for the panel module 39 shown in figs. 9a and 9b as seen from the front and from the side, respectively.

The cover plate 45 is made in one piece from a plate of a heat conducting material, such as aluminium, comprising a front surface 46 covering the elevated part of the panel module 39 and four side flaps 47 covering the sides of the elevated part of the panel module 39 approximately down to the upper edge of the corner parts 41 of the panel module. The front surface 46 of the cover plate 45 is provided with a large number of holes 48, which are aligned with the cavities 43 in the panel module 39 for improving the acoustic properties, when the cover plate 45 is mounted on the panel module 39.

Figs. 11a and l ib illustrates a panel module assembly 49 according to an embodiment of the invention comprising the panel module 39 shown in figs. 9a and 9b and the cover plate 45 illustrated in figs. 10a and 10b.

The panel module assembly further comprises a passageway for the cooling liquid (not shown) and the fluid inlet 50 and fluid outlet 50, which are illustrated in figs. 11a and l ib as well.

When a number of panel modules 39 have been mounted next to each other, the fluid inlets 50 and outlets 50 of neighbouring panel modules can easily be connected by a short piece of tube or hose, and these connections can be hid along with the four mounting screws (not shown) of adjacent panel module corners 41 behind a special cover plate (not shown) covering the corner parts 41 of four adjacent panel modules 39.

It should be noted that the described embodiments are exemplary only and are not in any way meant to limit the scope of protection, which is defined by the claims listed here below.

List of reference numbers

1. Cooling system

2. Cooling circuit 3. Cooling element

4. Ceiling

5. Room

6. Cooling hose

7. Ground 8. Deep ground loop

9. Closed end of deep ground loop

10. Circulating pump

11. Central Processing Unit (CPU)

12. Temperature sensor 13. Humidity sensor

14. Base cavity

15. Ground bore

16. Bentonite sludge

17. U-shaped pipe 18. Thermal insulation

19. Horizontal ground loop

20. Room cooled with cooling elements integrated in ceiling panels

21. Room cooled with a fan coil cooling element

22. Room cooled with cooling elements integrated in a hanging ceiling 23. Ceiling panel

24. Fan coil cooling element

25. Hanging ceiling

26. Slave Processing Unit (SPU)

27. Circuit valve 28. Mixer valve

29. Master Processing Unit (MPU)

30. Main valve

31. Pressure monitor

32. Driver station

33. Water inlet 34. Air outlet

35. Expansion tank

36. Heat pump

37. Floor heating system

38. Floor with heating system 39. Panel module

40. Recess for passageway for cooling liquid

41. Corner part of panel module

42. Mounting hole

43. Cavities for improving the acoustic properties 44. Recess for electric wires, etc.

45. Cover plate for panel module i

46. Front surface of cover plate

47. Side flap of cover plate

48. Holes for improving the acoustic properties 49. Panel module assembly

50. Fluid inlet/outlet for passageway for cooling liquid

51. Module core structure

52. Inner flat part of module core structure

53. Inclined parts of module core structure 54. Outer flat part of module core structure

55. Central aperture in module core structure

56. Corner protrusion of module core structure

57. Connection hose