Abstract:
An apparatus for providing localized heat transfer to or from a beverage includes a beverage container for containing the beverage; a dispenser, for dispensing the beverage; a delivery apparatus, disposed between the beverage container and the dispenser, for continuously delivering the beverage from the beverage container to the dispenser; at least one heating/cooling unit including at least one Peltier junction, operationally coupled to the dispenser, for heating/cooling the beverage in the proximity of the dispenser; a heat-transfer agent, coupled to the at least one heating/cooling unit, for transferring heat from the at least one heating/cooling unit; a venting device, operationally coupled to the heat-transfer agent, for venting the transferred heat; and a power supply device, operationally coupled to the heating/cooling unit, for supplying power to the at least one Peltier junction.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus and a method for providing localised heat transfer (either for cooling or for heating a body). 
     2. Description of Related Art 
     Although the present invention will be described herein with particular reference to the chilling of a beverage, it finds much wider application. For example, quantities of paint (or similar material) could be kept warm so that they may be applied more readily; localised chilling may be provided at supermarket check-outs to keep foodstuffs (such as ice-cream) cold. 
     Referring now to the treatment of beverages, it is desirable that some beverages, particularly though not exclusively beers, lagers and milk, are chilled before they are consumed. Beverages are frequently dispensed from taps and it is sometimes desirable that such tap-dispensed beverages are chilled before (and/or as) they are dispensed. 
     Previous cooling systems for chilling tap-dispensed beverages, have comprised large chilled rooms into which barrels of the beverage are placed and allowed to equilibrate. Once the temperature of the barrel is in equilibrium with that of the room, the contents will have been chilled to an appropriate temperature. Further cooling has sometimes been provided in the vicinity of the dispensing taps to ensure that the beverage is dispensed at the optimum temperature. 
     For large establishments having a number of beverages on tap, the known arrangement requires that a large chilled room is provided. This is expensive to run and maintain and moreover the known cooling systems have generally used, as the cooling medium, hydrocarbon-derived gases, which can be harmful if vented to the atmosphere. 
     BRIEF SUMMARY OF THE INVENTION 
     The Applicants have now devised a method of and apparatus for cooling beverages at the point of dispensing (in addition to or in place of cooling at the point of storage). Advantages of the method and apparatus of the present invention have been found to include: 
     (i) Reduced energy costs; 
     (ii) Environmentally more acceptable; 
     (iii) Reduction of the space required for chilling drink at the bar and therefore more space for stock; 
     (iv) Accurate temperature control and cooling at the dispensing point. 
     According to a first aspect of the present invention, there is provided a method of localised heat transfer to or from a container in which a cooling/heating unit including at least one Peltier junction is brought into proximity with the container and a heat transfer means is operatively associated with the cooling/heating unit, whereby either heat is removed from the unit (should heat be removed from the container) or heat is provided to the unit (should heat be supplied to the container). 
     Thus, a single cooling/heating unit can be provided which can be placed adjacent to a container and the container can be heated or cooled as desired. 
     According to a second aspect of the invention, there is provided a cooling apparatus comprising a beverage containment means, one or more cooling units, a cooling means, a venting means and a power supply means, the or each cooling unit including at least one Peltier junction and being placed adjacent the beverage containment means, the cooling means being adapted, in use, to remove heat from the container, the venting means being adapted, in use, to remove heat from the cooling means and vent it to the atmosphere and the power supply means being connected to the or each cooling unit and being adapted, in use, to power the or each Peltier junction. 
     This has the advantage that a self-contained unit is provided which can be used to chill the beverage containment means (rather than relying on a chilled room as was previously the case). 
     The apparatus of the present invention can also be used out-of-doors; since cooling is not being performed in an enclosed environment (a room), the location of the beverage containment means has no significance. 
     Further, the overall cost of the cooling system is reduced. If a new hotel, bar, restaurant, or the like is being set up, the capital outlay for the known cooling systems would be very high. A cooling system according to the present invention can be developed and/or extended as required. 
     Preferably, insulating means are provided which insulate the beverage containment means from its surroundings. This has the advantage that heat is not as readily absorbed by the beverage from the surroundings. Energy consumption should therefore be reduced when compared to a system not having insulating means. 
     The beverage containment means may comprise a barrel (or similar bulk storage container) and a delivery means associated therewith. 
     The delivery means may comprise a duct, pipe or the like, such apparatus being well known to those skilled in the relevant art. The delivery means may additionally be provided with further cooling means (such as a water-jacket), especially insulated “Python” tubing. 
     The cooling unit may be placed in association with the barrel or it may be placed in association with the delivery means. This allows flexibility in the arrangement of the system. 
     In a preferred embodiment, more than one cooling unit is provided; at least one in association with the barrel and at least one in association with the delivery means. 
     Most preferably, the cooling unit provided in association with the delivery means is located at or near an end portion of the delivery means adjacent to where the beverage is dispensed. 
     The beverage may be a beer, a lager, a stout, a cider, a soft drink, or any other such beverage customarily dispensed from taps in public houses, restaurants, hotels, and similar establishments. 
     Preferably, a pumping means is provided to pump the beverage from the barrel through the delivery means to the dispensing point. 
     The cooling means may consist essentially of a cooling fluid, preferably water. Other fluids, such as hydrocarbon-derived gases, may be used. Fluids are relatively easy to handle and to use as coolants. It is particularly advantageous to use water as the cooling fluid as it is cheap, readily available, non-toxic, and non-polluting. 
     The cooling fluid may be continuously re-circulated so that the system is economic in its use of coolant. 
     The venting means may comprise a radiator, which is a particularly convenient way of loosing heat to the atmosphere. The radiator may be fan-assisted, thus providing a more compact venting means for the throughput of heat required. 
     Preferably the power supply means comprises a mains-fed transformer, thus providing a relatively secure source of power. The power supply means could alternatively or additionally (for example as a back-up supply) comprise one or more batteries. 
     The transformer can preferably provide 24V DC from a mains supply. 
     The apparatus may be adapted, in use, to deliver beverages chilled to a selectable temperature, for example −12° C. to +12° C. Normal temperatures at which beverages are dispensed are in the range +2° C. to +8° C.). It is desirable to be able to vary the temperature at which the beverage can be dispensed, so that the same apparatus can be used to dispense a variety of different beverages. 
     Preferably the pressure of the cooling fluid is less than 2.5 bar. 
     In an embodiment having more than one cooling unit, the cooling fluid may flow through each of the cooling units in turn. This has the advantage that only one cooling means is required per apparatus (as opposed to one for each cooling unit) thus making the apparatus much more cost-effective. 
     Preferably, the insulating means comprises a jacket which is adapted, in use, to surround the barrel. The jacket may have an opening means to allow the barrel to be inserted into the jacket. 
     The cooling apparatus may be manufactured from food-grade materials, possibly in accordance with prescribed (e.g. European) standards. This allows the beverage to contact the cooling apparatus and remain consumable. 
     The Peltier junction may comprise two regions of dissimilar types of semiconductor, such as an n-doped region and a p-doped region. Using dissimilar semiconductor materials in this manner provides suitable properties for the junction. 
     Preferably, each cooling unit comprises a thermoelectric module consisting of a plurality of p-type and n-type conductivity elements, the elements being held between a pair of ceramic plates or other insulating material. On passage of a current through the conductivity-elements, one of the plates acts as a heat-absorbing (cooling) surface and the other plate acts as a heat-releasing (heating) surface. 
     According to a third aspect of the invention there is provided a method of cooling a beverage comprising placing a cooling unit adjacent a containment means to remove heat from a beverage contained within the containment means, the cooling unit including at least one Peltier junction adapted to cause a cooling means to remove heat from the junction and to vent the removed heat to the atmosphere. 
     Such a method is advantageous since it is much more efficient than known techniques of cooling a beverage. 
     Preferably the method comprises cooling the beverage in the containment means from an ambient temperature to a chilled temperature by using the cooling unit and subsequently maintaining the beverage at the chilled temperature. This has the advantage that the cooling of the beverage does not need to be completely performed as the beverage is dispensed. Thus, the power required for the cooling unit can be reduced. 
     The method may comprise cooling the beverage from an ambient temperature of 25-35° C. down to the chilled temperature of 10° C. or lower. For example, the chilled temperature may be set to be 8° C., or 6° C., or 4° C., or 2° C. 
     Preferably, beer can be dispensed from the beverage containment means through a delivery means and the delivery rate may be at least 600 cm 3  per minute. More preferably, the delivery rate may be about 1200 cm 3  per minute and most preferably is at least 2400 cm 3  per minute. Of course, the flow rate could be higher, perhaps 3000 cm 3  or 4000 cm 3  per minute. It has been found that these flow rates provide a convenient rate at which to dispense a beverage. 
     The method may further comprise continuously dispensing a beverage from a beverage containment means. 
     The beverage in the containment means may be cooled from the ambient temperature to the chilled temperature in from 6 to 14 hours, dependent on the starting temperature. 
     According to a fourth aspect of the invention there is provided the use of a cooling unit including at least one Peltier junction to cool a beverage. 
     The present invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the drawings (wherein like numerals denote like parts), 
     FIG. 1 is a schematic diagram of an apparatus according to the present invention for dispensing a chilled beverage; 
     FIGS. 2A,  2 B and  2 C show a suitable construction for an insulating cover and base for the beverage container of the apparatus of FIG. 1; 
     (Note: FIGS. 2B and 2C are, respectively, sections on lines A—A and B—B of FIG.  2 A). 
     FIGS. 3A,  3 B and  3 C show different types of heat-exchanger adapted in use to be inserted into the beverage container of the apparatus of FIG. 1; 
     FIGS. 4A,  4 B and  4 C show different types of heat-exchanger adapted in, use to be mounted on the beverage container of the apparatus of FIG. 1; 
     FIGS. 5A,  5 B,  5 C and  5 D show different types of heat-exchanger adapted in use to be placed at the base of the beverage container of the apparatus of FIG. 1; 
     FIGS. 6 and 7 show, respectively, hermetically sealed tanks for use in connection with “cold” and “hot” circuits for a cooling fluid for the apparatus of FIG. 1; 
     FIGS. 8A,  8 B and  9  show different types of “Python” multibore tubing suitable for use in connection with the apparatus of FIG. 1; 
     FIGS. 10A,  10 B,  10 C and  10 D show different constructions of heat-exchangers for contact, in use, with the beverage container of the apparatus of FIG. 1; 
     (FIG. 10A is a section on line  10 A— 10 A of FIG.  10 B and FIG. 10C is a section on line  10 C— 10 C of FIG.  10 D); 
     FIG. 11 is a centrifugal pump for use in connection with the apparatus of FIG. 1; 
     FIG. 12 is a schematic diagram of a Peltier junction for use in the apparatus of FIG. 1; and 
     FIG. 13 is a schematic perspective view of a cooling unit containing the Peltier junction of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a beverage container  1  comprising a barrel  10  having an insulating cover  11  and insulating base  12 . An extractor-tube type heat exchanger  14  is inserted into the barrel  10  and a dispenser head  13  is provided to permit the transportation of beverage from the barrel  10  to a dispenser unit  20 , via a fob detector  30  and tubing  31 . A heat exchanger  15  is placed in contact with the base of the barrel  10  and a hermetically-sealed “cold” tank  16  is placed between the heat exchanger  15  and insulating base  12 . A further heat exchanger  101  is mounted on the barrel  10  itself. 
     Movement of the beverage through tubing  31  from the barrel  10  to the dispenser unit  20  is assisted by means of a gas supply shown schematically at  17 . Circulation of a cooling fluid (e.g. water) through the system, together with movement of the beverage from the barrel to the dispenser unit, is suitably achieved by means of a thermo-insulated multibore tubing (shown schematically at  18 ), for example a “Python” tubing of a type known per se. 
     The barrel  10  is further provided with an external heat-exchanger  19  for chilling the beverage. 
     Electrical control of the apparatus is achieved by means of a thermoelectric block  21 , in operative association with a regulator  22 . 
     Cooling fluid (e.g. water) is circulated around the apparatus. From an expansion tank  23  provided with a gas compensator  24 , the fluid passes through a radiator  25  having an external fan  26 . Circulation of the fluid is achieved by means of a pump  27 . An air extractor (shown schematically at  28 ) is also provided and the cooling circuit also includes a hermetically-sealed “hot” tank  29 . 
     With reference to FIGS. 2A,  2 B and  2 C, the insulating cover  11  and base  12  for the barrel  10  of FIG. 1 are suitably provided with catches  111  and hinges  112  for ease of access to the barrel. 
     In FIGS. 3A,  3 B and  3 C, three different types of heat exchanger, adapted to be inserted into the barrel  10  of FIG. 1, are shown: 
     FIG. 3A shows an insert  14  having a spiral-tube heat exchanger, which screws into the barrel by means of union  141  and threading  142 . An extractor tube is adapted to be attached at  143 . 
     FIG. 3B shows a similar insert to that of FIG. 3A, in which the spiral tube carries a heat-transfer medium which also serves as a spring for an extractor valve. 
     FIG. 3C shows an insert which includes a cavity  144  for the heat-exchanger, a tube  145  for the heat-transfer medium and a tube  146  by way of which heat can be removed from the system. 
     FIGS. 4A,  4 B and  4 C show different barrel-mounted heat-exchangers: 
     In FIG. 4A there is shown a heat exchanger  101  having a spiral, hermetically sealed cavity to contain a coolant. The exchanger  101  also acts as a structural stiffener for the barrel. 
     In FIG. 4B there is shown a spiral pipe  102  to contain a coolant. 
     In FIG. 4C the barrel  10  is itself provided with a hermetically sealed cylindrical cavity  103  to contain a coolant. The cavity  103  also acts as a structural stiffener for the barrel. 
     Referring now to FIGS. 5A to  5 D, there is shown two types of heat-exchanger  15  suitable for location at the base of the barrel  10  of FIG.  1 . 
     In FIGS. 5A and 5B the heat-exchanger  15  comprises a base  151  on which is mounted an elastic membrane  152  containing a tubular heat exchanging means  153 . A mass  154  of a thermally-conductive material (which may be a gel, a fluid, a suspension of paste or a powder) is placed between the membrane  152  and the means  153 . 
     In FIGS. 5C and 5D the heat-exchanger  15  again comprises a base  151  on which a hollow elastic membrane  152  is mounted. The effective heatexchanger consists essentially of a part-spheroidal cavity  153 . A mass  154  of a thermally-conductive material is again placed between the membrane  152  and the cavity  153 . 
     The heat-exchanger  15  is operatively attached to the apparatus by means of a fixing unit shown schematically at  155 . 
     Referring to FIGS. 6 and 7, a tank  16  (for the “cold” circuit) and a tank  29  (for the “hot” circuit) are respectively provided with a flexible membrane  161  and  291 , the membrane forming one of the walls of each tank. When the apparatus is switched off, water returns under gravity to the tanks. Suitably, the membrane  161  ( 291 ) may be formed from a condom-type material. 
     In FIGS. 8A and 8B, two types of “Python” multibore tubing are shown. Generally, the inner tube  181  carries the beverage and the outer tube  182  carries the coolant, but both may be used for circulating the beverage through the apparatus. The tubes  181  and  182 , together with a flow line  183  for the coolant, are enclosed within respectively co-axial protective layers of a plastics material  184 , a foam material  185  and a plastics outer skin  186 . The cross-sectional area of the flow line  183  should in each case be equal to that of the outer tube(s)  182 , less that of the inner tube(s)  181 , irrespective of the number of inner tubes. 
     In FIG. 9 there is shown an alternative “Python” tubing, comprising a product tube  187 , a gilled return tube  188 , a gilled flow tube  189  and an insulating layer  190 , all tubes being arranged co-axially. 
     FIGS. 10A and 10B show a first type of external heat-exchanger  19  for use in the apparatus of FIG.  1 . The exchanger  19  is provided with a generally tubular means  192  to contain the heat transfer medium, the means  192  being enclosed in a membrane  191 . The space between the membrane  191  and tubular means  192  is filled with a mass  193  of a thermally conductive material. Locks, hinges, a stand and an attachment for a temporary tap are shown respectively at  194 ,  195 ,  196  and  197 . 
     In FIGS. 10C and 10D there is shown an alternative type of heat-exchanger  19 , in which the membrane  191  encloses a generally flat cavity  192  to contain the heat transfer medium. A mass  193  of a thermally conducive material is placed between the membrane and the cavity. 
     Referring now to FIG. 11, the centrifugal pump  27  has at least three sections: at least two sections are connected in series and have one input and two outputs operating at different pressures. At least one section is self-contained relative to the other sections. All sections are insulated from heat and all may conveniently be driven by means of a single electric motor. 
     As illustrated in FIG. 1, the barrel  10 , the several heat-exchangers, gas supply  17  and pump  27  are all located in a cellar. The dispensing unit  20  may be located in a bar area. The skilled person will appreciate that while it is of no significance where some parts of the system are located (for instance the pump  27 ), other parts will generally always be located in a certain place (for instance the dispensing unit  20  will generally always be located in a bar area). Other parts (e.g. the pipes carrying the various fluids) will need to pass through both areas. 
     In use, beer is delivered to the apparatus in barrels  10  which are at an ambient temperature, typically 25° C. The un-cooled barrel  10  is placed into the apparatus. Once the barrel is in place the apparatus is activated. 
     The pump  27  is switched on, thus circulating cooling water. Heat is drawn from the barrel  10  by the heat-exchangers and is transferred to the cooling water, thus raising the temperature of the cooling water. 
     The pump  27  forces the cooling water through the radiator  25  which dissipates the heat transferred to the water. The fan  26  assists in this process. 
     Gradually the temperature of the beer within the barrel  4  falls and after 6-14 hours the temperature has been reduced to the required temperature. The temperature selected depends on the beer contained within the barrel, but may suitably be in the range 8° C. to 2° C. 
     Once the beer has been sufficiently cooled it can be dispensed through the dispensing unit  20 . This is achieved by activating the beer pump  13 , drawing beer from the barrel  10  towards the dispensing unit  20 . 
     Suitably, the thermo-electric block may include a further block (hereinafter BPSR) which combines a power source and a regulator (both known per se). 
     Preferably, the BPSR has a substantially flat configuration for ease of mounting into the thermo-electric block. The components of the BPSR, together with any covering and/or housing, are preferably made from a non-corrosive material and all surfaces of the BPSR should be smooth and without corrosion or other damage. 
     Preferably, the dimensions and weight of the BPSR are reduced to a minimum, for example a height not exceeding 40 mm and a volume not exceeding 650 cm 3 . 
     Suitably, the resistance of insulation current circuits between the BPSR and any electrically-isolated circuits is not less than 20 MΩ (at 45-80% relative humidity and ambient temperature from +20° C.) and 1 MΩ (at 92-98% relative humidity and ambient temperature from +20° C.). All inner and outer circuits are separated and have no galvanic connection with the BPSR or with each other. Power may conveniently be supplied from A.C. mains and preferably the power consumption should not exceed 950 W. Preferably, the BPSR includes a safety device (e.g. a fuse) to protect against short-circuit or overheating of the thermo-electric block (for example, in the event of insufficient coolant in the block). 
     Preferably, the regulator is capable of maintaining the coolant temperature in the circuit to within ±0.5° C. of a given temperature in the range −1 to +10° C. 
     Maintenance of the required temperature may be achieved by means of a temperature-sensor in the cold circuit, together with a control circuit and the power source. 
     For example, a given temperature (Tg) in the cold circuit can be maintained by one of two possible methods so that the relationship of the temperature (Tc) of the cold circuit and the temperature (Th) of the hot circuit to the given temperature is Tc&lt;Tg&lt;Th (±0.5° C.): 
     Method (i) Reducing the voltage of the thermo-electric block to zero and supplying nominal voltage at Tg&gt;Tc; 
     Method (ii) Reducing the voltage of the thermoelectric block to 65% of the nominal voltage at Tc&lt;Tg and supplying nominal voltage at Tc&gt;Tg. 
     Maintenance of the temperature (Th) of the hot circuit is suitably achieved by means of a temperature-sensor in the hot circuit which acts to switch on a hot circuit pump. The sensor acts to break the contacts of the hot circuit pump relay when Th&lt;Tg and to close the contacts when Th&gt;Tg (±1° C.). 
     Preferably, the working mode of the BPSR is continuous and the block should function correctly at temperatures of between +10° C. and +32° C. As well as complying with applicable safety standards, the BPSR is suitably designed so that incorrect electrical connection is virtually impossible. 
     The several heat-exchangers are operated by means of Peltier coolers, the principle of which is shown in FIGS. 12 and 13. 
     Referring to FIG. 12, a power source  200  is provided to power the junction  202  of two dissimilar materials. In the preferred embodiment, doped semiconductors arc used: one portion of an n-doped semiconductor  204  and one portion of a p-doped semiconductor  206 . These two dissimilar materials are joined to each other by a joining conductor  208  and to the circuit by conductors  210 ,  212 . 
     Because of the Peltier effect which exists between dissimilar materials when a current is passed through the circuit from the power supply  200  the joining conductor  208  experiences a heating effect and the conductors  210 ,  212  experience a cooling effect. 
     Referring to FIG. 13, a thermoelectric module  300  consists of a plurality of conductivity elements  301  held between a pair of ceramic plates  302  and  303 . 
     A voltage V is provided by way of positive and negative supply leads,  304  and  305  respectively. 
     The arrangement of the elements  301  is such that plate  302  acts as a heating-absorbing (cooling) device and plate  303  acts as a heat-releasing (heating) surface. 
     Examples of how apparatus, incorporating one or more Peltier junctions according to the present invention, may be used in other applications include, but are not limited to, the following. 
     a) Cooling/chilling 
     ice cream and frozen food vending; 
     domestic refrigeration, drinks chillers, wine coolers etc, 
     transport refrigeration (refrigerators in cars, planes, trucks and ships); 
     industrial machinery cooling (injection moulding machines, laser cutting tools, metal and woodworking machinery, industrial drills and rock-cutting equipment, food processing plant and equipment); 
     specialist applications for the transport of organs, bodies etc. 
     b) Air conditioning 
     telecommunications and power supply equipment; 
     broadcasting and lighting equipment; 
     automotive and transport; 
     domestic/localised cooling. 
     c) Heating/warming 
     automotive and transport; 
     catering hot-plates and cabinets; 
     paint tin warmers and warming ovens/dryers in industrial applications; 
     washing machines; 
     heat curing systems for resins and epoxies. 
     Pettier plates can be used in conjunction with one or more coolants (water, gas, air) for different applications within the same system (heating, air conditioning and heating). An example of this is a vehicle using the same system to power a mini-refrigerator, an air-conditioning system and a seat-heating system. 
     The apparatus according to the present invention does not require any chloro-fluorocarbon coolants and in use does not generate environmentally-unacceptable emissions (such as the so-called “greenhouse gases”).