FIELD OF INVENTION

This invention relates to liquid dispensing systems with a mechanism for cooling liquids, in particular to on-demand liquid dispensing and cooling systems.

BACKGROUND OF THE INVENTION

Examples of a liquid dispensing system of the kind which the subject matter of the present application refers to, are described in US 2008/0196434, US 5,434,002 US 5,493,864, and US 6,450,360.

SUMMARY OF THE INVENTION

In accordance with one aspect of the subject matter of the present application, there is provided a liquid dispensing and cooling system comprising:

- a cooling device having a cooling device contact surface;

- a container configured to hold therein liquid to be cooled and having at least one wall of thermally conductive material with a container contact surface, the container, when with said liquid, having a first thermal mass; and

- a cooling block having a first cooling block contact surface in thermo- conductive contact with the container contact surface and a second cooling block contact surface in thermo-conductive contact with the cooling device contact surface, the cooling block having a second thermal mass which is at least twice the first thermal mass.

It is known that the thermal mass C _TH of a body is defined as C _TH ⁼ mc _p (J/°C) where m is the mass of the body (Kg), and c _p is the specific heat of the body (J/Kg°C).

It can be shown that the time during which one body having a thermal mass CTHI can change its temperature to anotlier temperature by means of its contact with another body having a thermal mass C _T H ₂ , is determined by the ratio between the thermal masses of the bodies so that the greater the difference between the thermal masses the shorter the time 't'.

The above dependency is used in the liquid dispensing and cooling system defined above, where the cooling block with its relatively large thermal mass is first cooled during a prior-to-demand period of the operation of the system, and then is used to cool the container having a relatively small thermal mass on-demand, by virtue of which the time required for cooling the container via the cooling block is shorter than the time required for cooling the container directly by the cooling device.

For example, when the cooling container is made of a thermo-conductive material, such as for example, aluminum and has thin walls and a relatively small volume, e.g. between 10ml and 100ml, its thermal mass together with liquid to be cooled will be in the range of 0.05 KJ/°C to 0.25 KJ/°C. If the thermal mass of the cooling block is twice that of the container, the time required to cool the liquid in the container will be half of that required to cool the container directly by the same cooling device. If the thermal mass of the cooling block is, for example, from five to ten times that of the cooling container with the liquid to be cooled, the time needed for the cooling block to cool such container will be between 20% and 10% of the time required to cool the container directly by the same cooling device.

The cooling block's contact surfaces can be adapted for tight direct contact with the corresponding contact surfaces of the container and the cooling device, and they can or can not be opposite to each other. Alternatively, the cooling block and the container can be produced as a single body and have a common wall, in which case their mutually contacting surfaces will be two opposite surfaces of that wall.

The cooling block can be a solid body of a suitable mass, made of a single material having a suitable specific heat. The container can be a hollow body fully or partially made of the same material as the cooling block.

The cooling block and the container can have their mutually contacting surfaces of same or similar shapes and dimensions. In this case, the dimension of the cooling block in the direction perpendicular to its first contact surface that is in contact with the container contact surface can be essentially greater than the corresponding dimension of the container. The ratio between these dimensions can be at least 2:1, in particular, at least 3:1, still more particularly, at least 4:1. In a specific example of the system, the ratio between the dimensions of the cooling block and the container, which are perpendicular to their mutually contacting surfaces thereof, can be in the range between 5:1 and 15:1, and more particularly in the range between 5:1 and 10:1.

The container and the cooling block can each be in the form of a plate, planar or curved, in which case the above ratio will refer to their thicknesses.

Alternatively, the cooling block and the container can be formed as a single cooling unit comprising: at least one internal wall,

at least two compartments to be filled with liquid to be cooled, the compartments being separated by said internal wall and being in successive fluid communication with each other,

an inlet in a first of the compartments; and

an outlet in a last of the compartments, which is closer to said cooling device than the first compartment;

wherein in at least one mode of the operation of such cooling unit, the first compartment constitutes the container, and the remaining compartments including the last compartment, together with liquid disposed therein, constitute the cooling block.

The cooling unit can have an external surface adjacent the last compartment and remote from the first compartment, which is configured to be in direct contact with the cooling device contact surface, thus constituting the cooling block second contact surface mentioned above.

In this case, the first compartment of the cooling unit will constitute the container and the internal wall that will separate it from the remaining compartments will have one surface constituting the first cooling block contact surface and the other surface constituting the container contact surface.

The cooling device can have a cold side in direct contact with said external surface of the cooling unit, and free of direct contact with any other walls of the cooling unit, and it can be configured to absorb heat from said external surface of the cooling unit and release the absorbed heat into the environment.

With the above construction, after the entire cooling unit has been cooled by the cooling device to a certain essentially uniform temperature during the prior-to- demand period of time, and then liquid is dispensed from the last compartment, e.g. as a result of a demand, and a new portion of liquid at an ambient temperature enters the first compartment, the first compartment starts functioning as the container with the new portion of liquid to be cooled, and the remainder of the cooling unit with liquid contained therein starts functioning as the cooling block, thereby essentially reducing the time and power required for the cooling device to have the new portion of liquid cooled, as explained above.

The cooling unit can have a plurality of partitions in at least one of the compartments, possibly at least the last compartment, dividing the compartment(s) into a plurality of cells in successive fluid communication with each other. This allows forming in the cooling unit a three-dimensional, multi-level (each compartment being a level) and multi-cell (within at least one compartment) labyrinth, for holding liquid therein when the system's inlet and outlet are closed and for having the liquid flowing therealong from said inlet to said outlet, when the inlet and the outlet are open. In the latter case, the labyrinth accommodates a flow path in which each compartment or cell has a more downstream or more upstream location relative to an adjacent compartment or cell.

The multi-level and multi-cell structure of the cooling unit facilitates the heat withdrawal from liquid held therein when the entire unit is to be cooled. Also, this structure, and particularly the multi-cell design of the compartments allows for the reduction or even prevention of the formation of air bubbles and turbulence in the flow passing therethrough, thus increasing the cooling efficiency of the system.

The cooling unit can comprise an integral cooling unit body formed with said internal walls and partitions, and with a cold external wall comprising said external surface configured to be in direct contact with the cooling device contact surface. The external wall can constitute one of the walls of the last compartment.

The cooling unit body can further comprise a warm external wall remote from the cooling device, which can constitute one of the walls of the first compartment.

The cooling unit can further comprise a pair of opposite fluid communication plates configured to be attached to two opposite sides of the cooling unit body, different from said external walls, and formed with inter-cell channels for providing fluid communication between adjacent cells within each compartment having such cells, and inter-compartment channels for providing fluid communication between adjacent compartments. One of these plates can comprise the inlet of the system and provide its fluid communication with the first compartment or, if the first compartment has cells, with the most upstream cell of the first compartment. The other plate can accordingly comprise the outlet of the system and provide its fluid ^' communication with the last compartment or, if the last compartment has cells, with the most downstream cell of the last compartment.

The cooling unit body can be made of a thermo-conducting material, and the fluid communication plates can be made of a thermally insulating material.

The cooling unit can further comprise a housing having thermally insulated walls and the cooling unit body and fluid communication plates disposed therein. If a coordinate system of X, Y and Z axes is applied to the above described system, the external and internal walls of the cooling unit body can be generally parallel to the X-Z plane of this coordinate system, and the partitions can be generally parallel to the X-Y plane. In this case, the compartments of the cooling unit can be arranged in succession along the Y axis, and the cells within each compartment having them can be arranged along the Z axis. It should be mentioned that it is not necessary for the external walls and/or internal walls, and/or the partitions to be planar. If any of them are designed to be curved, their orientation, when described with reference to the above coordinate system, is based on imaginary planes passing through their edges.

The cooling unit can have at least one intermediate compartment with respect to which at least the first compartment will be an upstream compartment and at least the last compartment will be a downstream compartment. In this case, the partitions if any in such intermediate compartment can extend between ^' the walls of the intermediate compartment that are common with the upstream and downstream compartments adjacent thereto. In each of the first and the last compartments, the partitions, if any, can extend between their wall common with an adjacent intermediate compartment and the respective warm or cold external wall of the cooling unit body.

The number of the cells in the compartments can differ and, for example, in at least one pair of two adjacent compartments it can be greater in a more downstream compartment, i.e. that of the two compartments which is closer to the outlet. Also, the volume of cells within one compartment can differ.

When the system is to be used as a portable system to provide an on-demand supply of cooled liquid for the purpose of consumption by a user, at least the last compartment, which is in direct fluid communication with the outlet, can have a volume from about 10ml to about 50ml, representing an average 'sip' volume range.

The system can be configured such that, once connected to a liquid source and first operated, it always has liquid present inside the compartments, which can be achieved by incorporating in the system a valve associated with the inlet thereof, configured to close the inlet, when said outlet is closed, preventing thereby the flow of liquid along said flow path while leaving said compartments filled with liquid.

With the cooling unit being filled with liquid, and the cooling device being capable of the operation in the range of powers including a maximal operating power PMAX and a minimal operating power PMIN, and being capable of changing the temperature of the entire system, when operating at the maximal power PMAX by ΔΤ ₀ ° within a predetermined period of time Δ¾ time, the system can operate in several modes, in which liquid in the cooling unit is cooled from its initial temperature TINITIAL to different temperatures in the range of desired cooling temperatures comprising a predetermined maximal cooling temperature TMAX, where T AX can, for example, be defined as normal human body temperature in the range of 35°C-37°C and minimal cooling temperature TMIN, the modes being, for example, as follows:

^■ a minimal-cooling or 'constant-on' mode with an intermediate power demand PINT, which is essentially greater than PMJN, e-g- is between PMINXIO and PMAX, i which mode the entire cooling unit with liquid contained therein is cooled by ΔΤ° ^χ η, where n=l when, when the ambient temperature is lower than 45°, or n=2, when the ambient temperature is greater than 45°C; this mode of operation thus results in the cooling unit constituting a reservoir full of reasonably cooled water;

a maintenance or 'stand-by' mode of operation with a power demand PMIN, in which water in the cooling unit is maintained at the maximal cooling temperature TMAX for a predetermined maintenance time after the 'constant-on' mode has been terminated; and a maximal cooling or 'boost' mode with a power demand PMAX, in which depending on the time of the system's operation in this mode and TINITIAL _, liquid in at least the last compartment is cooled by ΔΤ° ^χ Ν, where N>1, to a temperature which can be the minimal cooling temperature TMIN- With the structure and modes of operation of the system as described above, the cooling device can be in the form of a low power thermal-electric cooling element (TEC), e.g. having a maximal power in the range between 30 and 250Watt,in particular having a maximal power of 50 Watt. In the latter case, with the following exemplary characteristics of the system:

capacity of the cooling unit - lOOcc (100ml),

capacity of the last compartment - 20ml, AT=10°C and At ₀ =100sec;

maximal desired cooling temperature - 35°C, and

minimal desired cooling temperature - 15°C,

the system can operate in the above described modes as follows:

in the minimal-cooling high-power or 'constant-on' mode, liquid in the entire cooling unit is cooled to the maximal cooling temperature of TMAX or lower, in which case the power consumption can be 25- • 50 Watt;

in the maintenance-cooling low power or 'stand-by' mode, the power consumption can be the minimal power required to maintain the temperature reached during operation in the 'constant-on' mode; and in the maximal cooling high-power or 'boost' mode at least in the last compartment, and optionally in the entire cooling unit, liquid is cooled to the minimal cooling temperature, in which case the ^" power consumption can be 50 Watt.

In order to operate in the different modes of operation described above, the system can comprise a controller configured to switch between the modes of operation described above and to switch the system on and off, a temperature sensor configured to estimate the temperature of liquid in any location of the cooling block and to provide the controller with a control signal to start said 'stand-by' mode when the temperature of liquid at said location reaches its maximal desired cooling temperature, a timer configured to provide the controller with a control signal to switch off the system after the predetermined period of time during which it is designed to operate in the 'stand-by' mode, has passed, and a flow sensor configured to detect demand by a user and, when necessary, to provide the controller with a control signal to start the 'boost' mode upon the demand.

The cooling device can be configured to absorb the heat faster than it releases the absorbed heat. In order to facilitate the efficient transfer of heat from the cooling unit via the cooling device to the environment, the cooling device can comprise a cooling element having a cold side in direct contact with the external wall of the cooling unit, and a hot side spaced from the cold side, and a heat sink which is in heat-conducting contact with the hot side of the cooling element to absorb heat therefrom. The heat sink can comprise a heat dissipating member having a first volumetric heat capacity, and at least one thermal block embedded therein and having a second volumetric heat capacity greater than the first volumetric heat capacity, the thermal block having a heat absorbing surface in heat-conducting contact with the hot side of the cooling element and a heat releasing surface in heat-conducting contact with the heat dissipating member, due to which fast absorption of heat from the cooling element (e.g. during the operation time of the cooling element), and slow release thereof (e.g. during inactive time of the cooling element) can be obtained.

For example, the materials from which the thermal block and the heat dissipating member are made can be, respectively, copper having the volumetric heat capacity of 3.45 J/(cm ^{3 o} K) and aluminum having the volumetric heat capacity of 2.42 J/(cm ^{3 o} K)

The heat absorbing surface of the thermal block can have shape and dimensions corresponding to those of the hot side of the cooling element and a corresponding first area via which the thermal block contacts with the hot side of the cooling element,, and the heat releasing surface of the thermal block can have a second area via which it contacts with the heat dissipating member, exceeding the first area. For example, the heat releasing surface of the thermal block can have its area at least twice the area of its heat absorbing surface. By virtue of this, it is possible, on the one hand, to use the cooling device of a compact design, i.e. a thermo-electric cooling device with a relatively small area to which the heat absorbing surface of the thermal block can correspond, and on the other hand, to improve the heat transfer from the thermal block to the heat dissipating member via the thermal block's relatively large area of the heat releasing surface.

The following is a transient conduction equation which illustrates the effect of the area of the heat releasing surface of the thermal block on the amount of heat released thereby:

=1Α(Τ ₂ -Τ ₁ )Λ/(πατ), where:

A is the area of the heat releasing surface of the thermal block (m ² );

q is a heat flux passing through the area A (Watt(W) or J/s);

k is a conductivity constant of the material of the thermal block in(W/m°K); (T2 - Tl) is the change of temperature of the thermal block during which the heat flux q is released (°K); and

a is a diffusivity constant of the material in (W/m°K); τ is a transmissivity of the material in (W/m °K)

In view of the above, it is clear that the relatively large surface area of the heat releasing surface of the thermal block results in the prevention of the undue accumulation of heat in the thermal block and allows efficient dissipation of heat, e.g. during the inactive time of the system.

The system described above can further comprise a UV-C water disinfection device including an array of miniature UV-C radiation sources, such as e.g. UV-C LEDs, all having slightly different radiation wavelengths, which all together cover the range of UV wavelengths required for the UV disinfection. This range can be for example 240 - 280nm.

When used with the cooling unit having a plurality of cells in at least one of its compartment, each UV LED can be associated with one such cell.

In accordance with further aspect of the subject matter of the present application, there is provided a method of an operation of a system for dispensing and cooling liquid, the system having an inlet in fluid communication with a liquid source an outlet to dispense liquid to be used, and a flow path therebetween, the method comprising, in any order and timing, at least the following modes of operation of the system when filled with water via said inlet:

- operating the system in a first, minimal-cooling mode, including cooling the liquid to a maximal desired cooling temperature along the entire flow path;

- operating the system in a second, maintenance mode, including maintaining the liquid in the system at said maximal desired cooling temperature for a predetermined period of time; and

- operating the system in a third, maximal-cooling mode, including cooling the system to a minimal desired cooling temperature along at least a part of the cooling path.

The system to be operated by this method can comprise any one or more features described above with respect to the first aspect of the subject-matter of the present application, in any combination.

In accordance with a further aspect of the subject matter of the present application there is provided, for use in a liquid cooling system, a cooling unit having an inlet and an outlet, a plurality of external walls, of which at least one external wall is thermo-conductive, and the remaining walls are thermo-isolated, at least one compartment in fluid communication with the inlet and the outlet,, said at least one. external wall constituting at least one wall of said compartment , and a succession of cells within said compartment, defining a flow path, wherein a most upstream cell along the flow path is closest to said inlet and a most downstream cell along the flow path is closest to said outlet, each pair of adjacent cells having a common thermo- conductive inner wall, in direct or indirect thermal-conductive contact with said at least one wall of the compartment.

This cooling unit can comprise any one or more features described above with respect to the cooling unit of the system according to the first aspect of the subject- matter of the present application, in any combination.

In accordance with still further aspect of the subject matter of the present application, there is provided a cooling unit having an inlet and an outlet, and comprising a succession of compartments defining a flow path, wherein a first, most upstream compartment along the flow path is associated with said inlet and a last, most downstream compartment along the flow path is associated with said outlet, and wherein at least the last compartment has a volume between 10ml to 50ml.

The cooling unit can comprise any one or more features described above with respect to the cooling unit of the system according to the first aspect of the subject- matter of the present application, in any combination.

In accordance with a still further aspect of the subject matter of the present application, there is provided a cooling device for cooling a body comprising:

- a thermal-electric cooling element (TEC) having a cold side adapted for contacting said body, and a hot side; and

- a heat sink comprising a heat dissipating member having a first volumetric heat capacity and a thermal block having a second volumetric heat capacity greater than said first volumetric heat capacity;

- a heat absorbing surface in said thermal block in thermo-conductive contact with, and having the same shape and dimensions as, said hot side of the TEC, the heat absorbing surface having a first area;

- a heat releasing surface in said thermal block in thermo-conductive contact with said heat dissipating member, said heat releasing surface having an second area greater than said first area.

The heat sink can comprise any or more features described above with respecto the heat sink used in the system according to the first aspect of the subject matter of the present application, in any combination.

The cooling device can comprise any one or more features described above with respect to the cooling device of the system according to the first aspect of the subject-matter of the present application, in any combination.

In accordance with a still further aspect of the subject matter of the present application there is provided a UV disinfection device configured to provide liquid disinfection within in a pre-determined range of UV wavelengths, including an array of miniature UV radiation sources, such as e.g. UV LEDs, all having slightly different wavelengths, which all together constitute said pre-determined range.

The UV disinfection device can comprise any one or more features described above with respect to the UV disinfection device of the system according to the first aspect of the subject-matter of the present application, in any combination.

BRIEF DESCRIPTION OF DRAWINGS

In order to understand the subject at hand and to see how it can be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is a schematic isometric exploded view of one example of a system according to the subject matter of the present application;

Fig. 2 A is an isometric view of another example of a system according to the subject matter of the present application;

Fig. 2B is an exploded view of the system shown in Fig. 2A;

Fig. 2C is a side view of the system shown in Fig. 1 A;

Fig. 2D is a top view of the system shown in Fig. 2A;

Fig.3A and 3B are perspective views of a cooling block and a heat sink of the system shown in Figs. 2 A and 2B;

Fig. 4A to 4C are illustrations of respective first, second and third compartments of the system shown in Figs. 2A and 2B, if it was possible to view them in the directions designated as I-I, II-II and III-III, respectively in Fig. 2C;

Fig. 5A is an exploded perspective bottom view of a cooling device of the system shown in Figs . 2 A and 2B ;

Fig. 5B is a perspective top view of the cooling device shown in Fig. 5A;

Fig. 6 A and 6B illustrate the use of a UV-C disinfection in the system shown in Fig.

2A; and Fig. 7 is an illustration of one possible use of a cooling system of the kind to which the subject matter of the present application refers.

DETAILED DESCRIPTION OF DRAWINGS

Fig. 1 illustrates a liquid cooling and dispensing system configured for cooling liquid on demand, comprising a cooling device 2, a container 3 configured to hold therein liquid to be cooled and a cooling block 8 disposed between the cooling device 2 and the container 3.

The container 3 is in the form of a hollow, relatively planar body, with an interior (not seen) of a pre-determined volume corresponding to the amount of liquid to be cooled, two pairs of parallel external walls, including an upper wall 5', a lower wall 5", and side walls extending therebetween, whose height defines a thickness d of the container. The container 3 further includes an outlet 6 in fluid communication with the interior of the container and configured for connection to a user interface 7, for example a mouthpiece, and an inlet 4 in fluid communication with the interior of the container and having a filter 12 via which the inlet is configured for connection to a liquid reservoir (not shown).

The cooling block 8 is in the form of a solid body which has a first, lower cooling block surface 9' configured to be in thermo-conductive contact with the container upper wall 5', a second, upper cooling block surface 9" parallel to the surface 9' and configured to be in thermo-conductive contact with the cooling device 2, and side surfaces 10 therebetween whose dimension defines the cooling block's thickness D. The cooling block upper and lower surfaces 9' and 9" are of the same or similar shapes and dimensions as the container surfaces 5' and 5", and the cooling block's thicloiess D is essentially greater than the thickness d of the container 3. In the described example, the ratio between these dimensions is in the range between 5:1 and 10:1.

The cooling block 8 further includes in a thermo-insulating frame 11 which surrounds the cooling block along its periphery, being in contact with its side surfaces 10, and leaving the lower and upper surfaces 9' and 9" free for thermo-conducing contact with the container's upper surface 5' and the cooling device 2, respectively. The container 3 can also have a thermo-insulating arrangement, e.g. in the form of an external thermo-isolating layer, on all its walls except for the upper wall 5'.

The container 3 and the cooling block 8 can be made of the same material or different tliermo-conducting materials, which are such that when the container is filled with liquid to be cooled, it has a first thermal mass mi, and the cooling block has a second thermal mass ui2 which is essentially greater than the first thermal mass mi. In the described example, the container and the cooling block can both be made of aluminum and, with the dimensions described above; they can have the ratio between their thermal masses between 5:1 and 10:1.

^• The cooling device 2 contains a cooling element 16, e.g. a TEC and a heat sink 19 comprising a heat dissipating member 18 having a first volumetric heat capacity and a thermal block 20 embedded therein and having a second volumetric heat capacity greater than the first volumetric heat capacity.

The cooling element 16 has a first, lower contact surface 15 in thermo- conductive contact with the cooling block upper surface 9", and a second, upper contact surface 17, in thermo-conductive contact with the thermal block 20.

The thermal block 20 has a heat absorbing surface 20' (not seen) in thermo- conductive contact with the upper contact surface 17 of the cooling member 16, and a heat dissipating surface 20", whose area is essentially greater than that of the heat absorbing surface 20', which is in thermo-conductive contact with the heat dissipating member 18.

When the system 1 is assembled (not shown), the cooling block lower surface 9' is in tight direct contact with the upper surface 5' of the container 3, the cooling block upper surface 9" is in tight direct contact with the lower surface 15 of the cooling element 16, the upper surface 17 of the cooling element 16 is in tight direct contact with the heat absorbing surface 20' of the thermal block 20.

The system 1 further comprises a power control box 21, regulating the power supply to the system 1, which can be configured to be activated both upon demand at the outlet of the container or by an on/off switch, and operate the cooling device in at least the following modes:

- a first, minimal cooling or 'constant on' mode Ml in which the cooling block 8 is cooled to a desired cooling temperature by the cooling device where the cooling element operates at a certain, relatively high power; and

- a maintenance or 'stand-by' mode M2 to which the system is switched once in the mode Ml the cooling block 8 has reached the desired temperature, to maintain this temperature of liquid, the cooling element of the cooling device operating in this mode at a power essentially less than that in the mode Ml. The above modes of operation can take place both, at the time when the container 3 is full with liquid, and before the liquid enters the container 3. In the former case, in the mode Ml the cooling device 2 will cool the cooling block 8 which will cool the container 3 with liquid therein until the liquid reaches the desired temperature, and in the mode M2 both the cooling block 8 and the container 3 will be maintained at such temperature. In the latter case, when liquid enters the container 3 as a result of a demand by a user, the cooling block 8, being of substantially large thermal mass relative to the container 3 with liquid contained therein, rapidly absorbs the heat from the liquid and causes the liquid temperature to decrease, thus providing on demand cool liquid to a user. The system will then switch to the first Ml mode of operation to provide additional cooling and cool the cooling block 8 to the desired temperature in preparation for the next demand.

With reference to Fig.2A to 3B, there will now be described another liquid cooling and dispensing system, designated as 22, also configured for cooling liquid on demand. The system 22 differs from the system 1 mainly in that the system 22 comprises a cooling unit 43 which incorporates both a container and a cooling block, and the design of a cooling device 50 of the system. The system 22 will be described below with reference to a coordinate system X-Y-Z, where X-Z plane is parallel to surfaces along which a thermo-conductive contact between the cooling unit 43 and the cooling device 50 in the system 22 takes place.

The cooling unit 43 comprises a housing 35, a cooling unit body 37 with a plurality of compartments 45, 46 and 47, arranged in succession along the Y axis of the system, and fluid communication plates 40' and 40", all disposed within the housing, for providing fluid communication between different compartments. Each of the fluid communication plates 40', 40" has an inner side 30', 30" facing the cooling unit body 37 and an outer side 32', 32" facing the housing 35.

The housing 35 comprises an inlet 1 and an outlet 42 of the system 22, and a cover 38 including means for allowing a thermo-conductive contact between the cooling unit body 37 and the cooling device 50. In the system 22 this means is in the form of two openings 36.

The cooling unit body 37 comprises a pair of parallel external side walls 34' and 34" extending between an external upper wall 33", an external lower wall 33', and a plurality of internal walls 34 separating between, and defining, the compartments 45, 46 and 47. The upper and lower external walls 33" and 33', as well as the internal ^• walls 34, extend parallel to the X-Z plane of the system. The external side walls comprise means 39 for mounting thereto the fluid communication plates 40', 40".

The compartment 45 is a first compartment and it is defined between the lower external wall 33', and one of the internal walls 34, which is common between the first compartment 45 and the compartment 46 adjacent thereto. The compartment 46 is an intermediate compartment defined between two internal walls 34. The compartment 47 is a last compartment, and it is defined between the upper external wall 33" and the internal wall 34 which is common between the last compartment 47 and the intermediate compartment 46.

Each compartment 45, 46, 47 is divided by a plurality of partitions 31 into a succession of cells 45A to 45 _C; 46A to 46p, and 47A to 47 _¾ respectively. Each partition extends parallel to the X-Y plane of the system and perpendicular to the internal wall 34. However, the orientation of the partitions 31 does not necessarily need to be as described above. For example, they can extend relative to the X-Y plane at an angle other than the right angle and/or can be not perpendicular to the X-Z plane.

Each of the above cells, except for the cells adjacent the side walls 34' and 34", is in fluid communication only with an adjacent cell within the same compartment, whilst the cells adjacent the side walls 34' and 34" are in fluid communication either with corresponding cells of another compartment or with the inlet 41 or the outlet 42. The fluid communication of the cells as described above is provided by means of the communication plates 40', 40" so as to form a multi-level three-dimensional labyrinth, where each level of the labyrinth is defined by the cells of one compartment. .

With reference to Figs. 3A and 3B, the communication plates 40', 40" comprise respective fluid communication passages 48', 49', 48" and 49" formed on their inner side 30', 30", outer side 32', 32" and therebetween, to provide fluid communication between different cells of different compartments of the cooling unit, as described above..

In particular, the plate 40" is formed with an inlet passage 41 ' extending between the inner and outer sides of the plate 40", providing fluid communication between the inlet 41 and the first cell 45A of the compartment 45, and the plate 40' includes an outlet passage 42' extending between the inner and outer sides of the plate 40', providing fluid communication between the last cell 47H of the compartment 47 and the outlet 42. Also, the inter-cell passages 48', and 48" providing fluid communication between adjacent cells in each compartment. In addition, the plate 40' comprises an inter-compartment passage 49' providing fluid communication between the last cell 45 _c of compartment 45 and the first cell 46 _A of the compartment 46, and an inter-compartment passage 49" providing fluid communication between the last cell 46F of the compartment 46 and the first cell 47A, of the compartment 47.

The cooling unit body 37 with its compartments and cells is made of a thermo- conductive material, for example aluminum, whilst the fluid communication plates 40' and 40" and the housing 35 are made of thermo-insulating material, for example ABS Plastic Resin and Styrofoam, respectively.

In consequence with the above described multi-compartment and multi-cell design of the cooling unit body 37, a multi-level labyrinth, and consequently, a three dimensional flow path F is obtained, as illustrated in Figs. 4A to 4C, comprised of compartment flow components F ₄ 5 _S F ₄₆ F47 each disposed in a plane parallel to the X-Z plane, and inter-compartment flow components F _{45 -4} 6 and F _{46 -47} each disposed in a plane parallel to the X-Y plane.

Clearly, the cooling unit body 37 can have any number of compartments and each compartment can have any number of cells, and consequently the flow path will have a corresponding number of levels, cell sections at each level, inter-level and inter-- cell sections.

Further, the cooling unit body can have any dimensions depending on the purpose for which the system is designed, however, it can be advantageous at least for on-demand applications to have at least the last compartment, with such volume as to provide a single-use amount of liquid at the lowest possible temperature. For example, such volume can be in an average 'sip' volume range, i.e. from about 10ml to about 20ml.

With reference to Fig. 2B, 5A and 5B, the cooling device 50 comprises a cooling element in the form of two cooling members 52, e.g. thermo-electric cooling (TEC) plates, disposed on two sides of the Z axis of the system, and a heat sink 53 including a heat dissipating member 58 having a first volumetric heat capacity, and a thermal block having a second volumetric heat capacity greater than the first volumetric heat capacity, the thermal block being in the form of two heat absorbing members 55 embedded in the heat dissipating member 58 and configured for being received in the openings 36 of the cover 38.

Each cooling member 52 has a cold side 52' in direct heat-conducting contact with the upper external wall 33" of the cooling unit body 37, and hot side 52" with the corresponding heat absorbing member 55 of the thermal block 54.

Each heat absorbing member 55 has a heat absorbing surface 55' of a first area, which is in heat conducting contact with the hot side 52" of the cooling member 52, and a heat dissipating surface 55" of a second area, in heat conducting contact with the heat dissipating member 58, the heat dissipating surface 55" including all surfaces of the heat absorbing member 55 except for its heat absorbing surface 55', and its second area is thus essentially greater than the first area mentioned above.

The heat dissipating member 58 has a base 58' at one side of which the heat absorbing members 55 are embedded, and the other side of which is formed with a plurality heat dissipating fins 58" , each having at least two heat dissipating surfaces parallel to either X-Y or Y-Z plane.

The cooling device 50 operates as follows: the cooling members 52 having their cold side 52' in contact with the upper external wall 33" (Fig. 2B) of the cooling unit body 37 withdraw heat therefrom and transfer the heat to their hot side 52"; the heat is then absorbed by the heat absorbing members 55 and dissipated to the environment via the base 58' of the heat dissipating member 58 and the heat dissipating fins 58". When the heat is withdrawn from the external wall 33" of the cooling unit body 37, all the internal walls 34 and partitions 34' of the body are cooled. Consequently, all sections of the multi-level labyrinth flow path F within the cooling unit body 37, between and including the first compartment cell 45A of the first level F ₄₅ and the last compartment cell 47H of the last level F ₇ , are cooled until the liquid therein reaches the same desired temperature.

Reverting to Fig. 2A, the system 22 can further contain the following:

- a valve 60 associated with the inlet 41 of the system 22;

- a temperature sensor 62 configured to estimate the temperature in one or more compartments of the cooling unit 43, e.g. in the last compartment 47;

- a timer 63;

- a manual control device 64 configured to indicate to the controller to operate the system at maximum power;

- an on/off switch 65;

- a flow sensor -67 configured to indicate the existence of flow through the cooling unit body 37; and

- a controller 66 configured to receive signals from the on/off switch 65, the temperature sensor 62 and the manual control device 64, and to switch the system 2 between its different modes of operation, which will be described in more detail below.

The system with the above components can be configured to operate on- demand as follows: once the switch 65 is in its On' position, the inlet 41 connected to a liquid source is open, the outlet 42 is closed, applying 'demand' suction by the user at the system outlet 42 will open the outlet 42 and will cause liquid to enter the inlet 41 and fill the compartments 45, 46 and 47 of the cooling unit body 37. If no suction is further applied, the outlet 42 is closed, the cooling unit body 37 becomes fully filled with the liquid, the flow sensor 67 will provide the controller 66 with a corresponding signal and the controller will control the valve 60 to close the inlet 41.

With the cooling unit 43 being filled with water, and the cooling device 50 being capable of the operation in the range of powers including a maximal operating power PMAX and a minimal operating power PM _I N, and being capable of changing the temperature of the entire system when operating at the maximal power PMAX by ΔΤο within a predetermined period of time Δ¾, the system can operate in several modes, in which liquid contained in the liquid cooling unit 43 is cooled from its initial temperature T _I NIT _IAL to different temperatures in the range of desired cooling temperatures, comprising a predetermined maximal cooling temperature TM _A X and minimal cooling temperature T _MI N, the modes being as follows:

- a first, minimal cooling or 'constant on' demand mode Ml in which the entire cooling unit 43 with liquid contained therein is cooled by ΔΤ° x n to the maximal cooling temperature T _MA X, where n depends on P _I T and TINITIAL and its value can be in the range between 1 and 2; this mode of operation thus results in the cooling unit constituting a reservoir full of reasonably cooled liquid;

- a maintenance or 'stand-by' mode M2 of operation with a power demand PMIN, in which liquid in the cooling unit 43 is maintained at the maximal cooling temperature TMAX for a predetennined maintenance time after the 'constant-on' mode has been terminated; and

- a maximal cooling or 'boost' mode M3 with a power demand PMAX, i which depending on the time of the system's operation in this mode and TINITIAL, liquid in at least the last compartment is cooled by ΔΤ° ^χ Ν, where N>1, to a temperature which can be the minimal cooling temperature TM _I N-

In operation, activation of switch 65 will signal the controller 66 to switch the system to operating mode Ml. When liquid in the cooling unit 37 has reached its maximal cooling temperature TM _A X the temperature sensor 62 will signal the controller to switch the system to operating mode M2, in which the system will operate for a predetermined period of time as indicated by timer 63.

If no demand for liquid is sensed by the flow sensor 67 after the predetermined period of time, the controller 66 will switch the system off until the flow sensor 67 indicates demand by a user or switch 65 is manually activated.

If a demand has been detected by the flow sensor 67 , the latter signals the controller 66, and liquid from the last compartment 47 will be supplied via the outlet 42 to the user at the maximal cooling temperature, whilst a new portion of liquid will enter the first compartment 45 from the inlet 41. From now on, the system will operate in the third, maximal cooling mode M3 to bring liquid the cooling unit 37 to the minimal cooling temperature. The system will operate in this mode until the temperature sensor 62 signals the controller 66 that liquid in the last compartment 47 has reached the minimal cooling temperature. Comparing this manner of operation of the system 22 with that of the system 1 shown in Fig. 1, it is clear that the first compartment 45 in the system 22 functions in the same way as the container 3 of the system 1, and the compartments 46 and 47 with liquid contained therein, function in the same manner as the cooling block 8 of the system 1.

The controller 66 can be configured to switch the system once demand, as indicated by flow sensor 67, has ceased, to the mode Ml or M2, depending on the temperature in the cooling unit,.

When desired by a user, activation of manual control 64 will indicate to the controller 66 to switch the system to mode M3 for cooling liquid in the last compartment 47, in the entire cooling unit 37, or a portion thereof (depending on the time of the activation) to the minimal cooling temperature TM _I N-

The controller 66 can be configured to switch the system to the mode M2 once the operation in the mode M3 has ceased.

With reference to Figs. 6A to 6B, the system 22 can be provided with a UV-C water disinfection device including an array of UV-C LEDs 68, which all together cover the total range of UV wavelengths required for the UV disinfection, this range being for example 240-280nm. The UV-C LEDs 68 array extends along the compartment 47 and each LED therein having its own small range of radiation wavelengths within the above total range, is associated with one cell in this compartment, to irradiate liquid in each cell with radiation in its small range. The UV-V LEDs 68 are coupled to an electronic circuit board 69 which activates the UV-C LEDs 68 upon activation of the system by the controller 66.

In order to increase the efficacy of the disinfection the inner walls of each cell can be polished to a mirror finish thus increasing their reflectivity and reducing beam energy loss due to absorption by the wall surfaces.

The system as described above can have any desired design to suit its intended use. For example, its housing can have a shape to suit the geometry of the surface intended for carrying the system, as illustrated in Fig. 7.

Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations and modifications can be made without departing from the scope of the invention mutatis mutandis.