GB2121943A

GB2121943A - Heat exchange apparatus

Info

Publication number: GB2121943A
Application number: GB08312310A
Authority: GB
Inventors: Neil Eric Paxman
Original assignee: PAXMAN SLATER COOLERS Ltd
Current assignee: PAXMAN SLATER COOLERS Ltd
Priority date: 1982-05-05
Filing date: 1983-05-05
Publication date: 1984-01-04
Also published as: GB2121943B; GB8312310D0

Abstract

Apparatus for cooling and dispensing wine or beer comprises a refrigeration unit 2 and a cooling and dispensing unit 3. The refrigeration unit 2 comprises an evaporator tank 4, and a compressor 5 with condensor 6 under thermostatic control. The tank 4 is of modest capacity, and in it water is cooled by the refrigerant. The water flows via lines 10 and 11 to and from the unit 3, where it cools the wine or beer passing through coils within the unit 3. A thermostat 19 responds to the temperature within the unit 3, to control flow of coolant water through the lines 10 and 11. There is a relatively large contact surface area between the refrigerant coils and water in the tank 4, and between the wine or beer coils and water in the unit 3. There is a relatively small amount of water in the entire circuit between the tank 4 and the unit 3. Therefore, the system acts with very low thermal inertia, and heat may be transferred quickly between the wine or beer and the refrigerant, via the coolant water. <IMAGE>

Description

SPECIFICATION Heat exchange apparatus This invention relates to heat exchange apparatus, and is particularly although not exclusively concerned with apparatus for cooling wines and beers which are dispensed by means of a pump.

Most beer coolers in use at the present time are not designed to provide cooling with any degree of accuracy. Often, they consist of a large reservoir of coolant water, which is cooled by means of refrigerating coils driven by relatively small capacity compressors. Usually, these compressors are run continuously in non-working periods of a bar to build-up ice in the reservoir.

During working periods, the water is circulated through the reservoir and in thermal contact with the beer, to cause cooling thereof. Unfortunately, if the ice dissolves during working periods, which happens quite often, it will not recover sufficiently to cool the beer for a number of hours. Thus, during a busy working period and/or in warm conditions, the beer gets progressively warmer until, perhaps, no appreciable cooling is effected at all.

In such beer cooling apparatus as is described above, the heat exchange between the coolant water and the beer often takes place by way of a "Python", which consists of a length of larger diameter tubing containing lengths of smaller diameter tubing. The beer or other products run through the smaller diameter tubing, whilst the coolant water is caused to flow throughout the large diameter tubing, to cool the beer and other products.

It may thus be appreciated that the degree of cooling afforded by such systems can vary considerably with varying conditions, and is generally quite unpredictable. A further practical disadvantage of using a "Python" system is that it is unsuitable for hand-drawn beer, which is required to run through relatively large diameter tubing, which cannot readily be accommodated within further tubing.

Certain bar-mounted coolers have been proposed to cool beer at or adjacent the point of dispense. However, these again have not been very accurate or reliable in their cooling, and also tend to be unable to cool the first few ounces of a product to be dispensed, if the dispenser has not been used for a little while. Although this may not be totally unacceptable in dispensing pints of beer, it can be quite unacceptable in dispensing relatively small quantities of wine, for example.

Preferred embodiments of the present invention aim to provide cooling apparatus for beer, wine or other products, which may be generally improved in the foregoing respects.

More generally, according to a first aspect of the present invention, there is provided a heat exchange apparatus comprising: first and second heat exchangers; first means passing a primary heat-exchange medium through said first heat exchanger; second means for circulating a secondary heat exchange medium through both said heat exchangers; and third means for passing a product through said second heat exchanger and dispensing the product directly at or adjacent the second heat exchanger.

Preferably, at least one of said heat exchangers comprises a tank which contains a heat exchange coil and is provided with a fluid inlet and a fluid outlet so arranged that fluid travelling from the inlet to the outlet passes through and/or around a major part of the coil.

The first heat exchanger preferably comprises a tank containing a close-wound heat exchange coil, the tank and coil being elongate in crosssection, and a fluid inlet is provided at one end and side of the tank, and a fluid outlet is provided at the same end but opposite side of the tank.

The second heat exchanger may with advantage comprise an elongate tank containing an elongate heat exchange coil, a fluid inlet provided at one end of the tank, and a fluid outlet provided at an opposite end of the tank. The second heat exchanger preferably comprises a further heat exchange coil wound around the said elongate coil with its axis substantially perpendicular thereto. In such an arrangement, the said coils of said second heat exchanger are preferably adapted to carry respective products to be dispensed by said third means.

In a particularly advantageous embodiment, the said third means comprises at least one hand pump.

Preferably, the said first heat exchanger comprises an inlet for said secondary heat exchange medium, which inlet comprises spray nozzle means.

The first and second heat exchangers preferably comprise respective reservoirs for said secondary heat exchange medium, Means may be provided for filling said reservoirs individually, thereby to charge a circuit for said secondary heat exchange medium.

The primary heat exchange medium may be a refrigerant and the secondary heat exchange medium a coolant. The apparatus may then comprise a compressor and a condenser for said refrigerant, and the compressor, condenser and first heat exchanger may with advantage form part of a portable refrigeration unit.

The heat exchange areas of said heat exchangers and the flow rates of said heat exchange media and product are preferably such as to provide substantial uniformity of temperature between said heat exchange media at the output of said secondary heat exchange medium from said first heat exchanger and/or substantial uniformity of temperature between said secondary heat exchange medium and the product at the output of said secondary heat exchange medium from said second heat exchanger.

Preferably, the apparatus includes a first thermostat adapted to control the flow of said primary heat exchange medium through said first heat exchanger, in response to the temperature of said secondary heat exchange medium at or adjacent the outlet thereof from the first heat exchanger. The apparatus may further include a second thermostat adapted to control the flow of said secondary heat exchange medium through said heat exchangers, in response to the temperature of said secondary heat exchange medium in the second heat exchanger. The second thermostat is preferably adapted to respond to an average temperature of the secondary heat exchange medium in the second heat exchanger.

Preferably, the mass of said secondary heat exchange medium is sufficiently small as to provide no appreciable heat store in the apparatus.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 is a perspective view of a beer or wine cooler embodying the present invention; Figure 2 is a plan view of a product cooling module thereof, showing coils within the module; Figure 3 is a plan view of an evaporator tank of the cooler, showing an evaporator coil thereof; and Figure 4 is a side view of the evaporator tank, showing the evaporator coil.

The illustrated apparatus is for cooling and dispensing beer or wine or any other liquid product.

It comprises a portable refrigeration unit 2, and a product cooling and dispensing unit 3.

The portable refrigeration unit 2 comprises a first heat exchanger in the form of an evaporator tank 4 through which there is passed a primary heat exchange medium in the form of a refrigerant. The circuit for the refrigerant includes a compressor 5 and a condenser 6, together with a fan unit 7 for cooling the condenser. A first adjustable thermostat 8 is provided on the unit 2, and is adapted to control operation of the refrigeration cycle of the refrigerant.

A pump 9 is also mounted on the refrigeration unit 2, and is connected to pump through the evaporator tank 4 a secondary heat exchange medium in the form of a coolant. By way of typical example, it will be assumed that the coolant is water. The pump 9 pumps the water through the evaporator tank 4 and also through the product cooling and dispensing unit 3, by way of flow and return lines 10 and 11.

The product cooling and dispensing unit 3 comprises a second heat exchanger in the form of a product cooling module 12, upon which there are mounted two hand pumps 13 and 14, each of which has a respective dispensing nozzle 1 5.

Water from the refrigeration unit is caused to flow through the product cooling module 12, via the flow and return lines 10 and 1 The product to be dispensed is supplied to each of the pumps 13 and 14 via a respective inlet line 16. From each pump 13 and 14, the product is caused to flow through the product cooling module 12 via respective product flow and return lines 1 7 and 1 8. From each of the respective return lines 18, the product is dispensed directly through the respective dispensing nozzle 1 5.

A second thermostat 1 9 is provided to control the pump 9 on the refrigeration unit, and thereby the coolant cycle.

Both the evaporator tank 4 and the product cooling module 12 have a respective filling cap 20 and 21, by means of which water can be introduced.

Figure 2 illustrates the internal arrangement of the product cooling module 12, which comprises an elongate tank 22, housing first and second product coils 23 and 24, which serve as heat exchange coils through which the products from the respective hand pumps 13 and 1 4 are caused to flow. A water inlet 25 and a water outlet 26 are provided respectively at opposite ends of the tank 22.

As may be seen from Figure 2, the first product coil 23 is an elongate coil, with its axis parallel to that of the tank 22. The second product coil 24 is wound around the first product coil 23, with its axis substantially perpendicular thereto. A gap is provided between the second product coil 24 and the walls of the tank 22. The first and second product coils 23 and 24 are so wound as to permit the flow of water between the turns of the coils.

In use, water is caused to enter the tank 22 through the inlet 25, where it immediately meets and is dispersed by the turns of the second product coil 24. As the water passes through the tank 22 towards the outlet 26, it is subjected to an appreciable degree of turbulence because of the obstructions presented by the turns of the product coils 23 and 24. Having regard to the substantial heat exchange area afforded by the product coils 23 and 24 in the tank 22, there is thus ensured thorough heat exchange between the water and the products in the coils 23 and 24.

It will be appreciated that the water passing through the tank 22 passes through and/or around virtually the whole of the coils 23 and 24.

The internai arrangement of the evaporator tank 4 is shown in more detail in Figures 3 and 4.

The tank 4 is alongate in cross-section, and contains the evaporator coil 27 as a heat exchange coil, which is close wound and is also elongate in cross-section. A water inlet 28 is provided at one end and side of the tank 4, and a water outlet 29 is provided at the same end but opposite side of the tank 4. A temperature probe 30 is connected to the first thermostat 8 and is situated adjacent the water outlet 29.

The water inlet 28 comprises a pipe having a plurality of spray nozzles 31 through which water is sprayed into the tank 4. Because of the close wound turns of the coil 27, the water is caused to flow principally around the coil 27 from the inlet 28 to the outlet 29. The evaporator coil 27 is of a size comparable to that of the tank 4, and the water flows around most of the coil 27 in its passage from the inlet 28 to the outlet 29.

A second temperature probe 32 for the second thermostat 19 is positioned in the tank 22 (Figure 2), and extends well into the tank 22, so as to respond to an average temperature of the water within the tank 22.

The illustrated apparatus is used as follows.

The product cooling and dispensing unit 3 is situated at a bar, and the portable refrigeration unit 2 is situated at any convenient location, either near or far away from the bar. The water flow and return lines 10 and 11 are connected between the product cooling and dispensing module 3 and the refrigeration unit 2, as is the second thermostat 1 9.

The filling caps 20 and 21 are removed from the evaporator tank 4 and the product cooling module 12 respectively, and water is introduced into the evaporator tank 4 (assuming that this is below the module 3). When the evaporator tank 4 is full, the filling cap 20 is replaced, and water is then introduced into the product cooling module 12. When the tank 22 is full, the cap 21 is replaced. The apparatus is then substantially fully charged with water, and the apparatus may then be switched on, such that the pump 9 runs to circulate water around the apparatus. (In practice, the tank 22 will have to be topped up again after a short while, to compensate for any air that may have been in the system). It is important to note that, because the water circuit can be charged in this manner, the pump 9 may be of relatively modest capacity. It does not have to develop any significant head.It merely has to pump the water around the charged system.

The first thermostat 8 is preset to a desired minimum water temperature adjacent the water outlet 29 in the evaporator tank 4. This setting may be adjusted as required. The second thermostat 19 is adjusted to a required temperature for the product to be dispensed by the pumps 13 and 14. When the temperature of the water in the tank 22 is too high, the pump 9 is actuated, and water is pumped around the system, through the evaporator tank 4. If the water leaving the tank 4 is too warm, the first thermostat 8 cuts in to activate the refrigeration cycle, and the water passing through the evaporator tank 4 is then cooled. The cool water then passes through the tank 22, where it cools the product in the coils 23 and 24.

It is to be appreciated that the mass of water in the system is sufficiently small as to provide no appreciable heat store in the apparatus. Thus, for example, it is not necessary for the evaporator tank to make any ice as a reservoir on which long term cooling of the water depends, although in practice a small amount of ice may build up within the evaporator coil 27 from time to time.

By contrast, the whole apparatus-operates with very low "thermal inertia". Heat from the products is transferred almost immediately into the water flowing through the product cooling module 12, and this heat is given up in the evaporator tank almost immediately, as the water passes through it. This is because the heat exchange area of the product cooling module 1 2 and the flow rate of the water passing through the module are such as to provide substantial uniformity of temperature between the water and the products at the water outlet 26 of the tank 22. Also, the heat exchange area afforded by the evaporator coil 27 and the flow rate of the water passing through the evaporator tank 4 are such as to provide substantial uniformity of temperature between the refrigerant and the coolant at the water outlet 29 of the evaporator tank 4.

Because of the relatively modest amount of water in the evaporator tank 4 at any time, the relatively large compressor 5 may exert a significant cooling effect on the water, with a very low response time.

It may therefore be appreciated that the illustrated beer or wine cooler may provide simple and effective cooling of any product, to any desired temperature. The apparatus may be conveniently located where required, and the fuily charged water system enables the pump 9 to pump water quickly around the apparatus. (On a very long run, the flow and return lines 10 and 11 may be insulated). An important advantage of the illustrated apparatus is that the products are actually cooled as they are being dispensed. There is no significant quantity of product remaining in the pumps 13 and 14 at ambient temperature, so that the apparatus may be used most successfully for dispensing small glasses of wine, even at infrequent intervals. Also, cooling takes place only as and when required.There is no tendency for the products to be over cooled at any point in the apparatus, if there is a long period between dispensing operations. This is helped by the remote location of the product coils 23 and 24 from the evaporator coil 27. By contrast, in previously proposed coolers, where product coils share the same tank as a refrigeration coil, then very low product temperatures can be reached overnight (for example) which, in the case of wine, may cause the product to crystallize and eventually block the product coil.

The illustrated apparatus therefore serves to cool and dispense beer, wine or other products with uniform temperature control, cooling of the product being carried out at the point of dispense.

In experiments, we have found it possible to dispense products as quickly or as slowly as desired, whilst maintaining a temperature control to within two degrees F. of a desired setting.

The illustrated apparatus may be modified in a number of ways. There may be provided a plurality of pumps 9 each supplying a respective cooling and dispensing unit 3, by way of respective flow and return lines 10 and 11. The size of the evaporator tank 4 and the compressor 5 may have to be increased somewhat, but the overall system would still operate with low "thermal inertia".

It is mentioned above that the water circuit between the unit 3 and tank 4 is fully charged. An important advantage of this is that the relatively small pump 9 may nevertheless pump over relatively large distances.

In an alternative arrangement, the two product coils 23 and 24 may be closely wound together, both around the edge of the tank 22. The arrangement may then be such that the water flow through the tank 22 is predominantly around the coils 23 and 24, which are preferably in close contact to facilitate heat transfer therebetween.

The temperature probe 32 may, in such a case, comprise a coil which is interwoven around the coils 23 and 24.

For reasons of safety, the thermostat 1 9 may operate at a low voltage (e.g. 12 v or 24 v), and control a higher voltage relay adjacent the pump 9.

Claims

Claims

1. Heat exchange apparatus comprising: first and second heat exchangers; first means for passing a primary heat exchange medium through said first heat exchanger; second means for circulating a secondary heat exchange medium through both said heat exchangers; and third means for passing a product through said second heat exchanger and dispensing the product directly at or adjacent the second heat exchanger.

2. Apparatus according to Claim 1, wherein at least one of said heat exchangers comprises a tank which contains a heat exchange coil and is provided with a fluid inlet and a fluid outlet so arranged that fluid travelling from the inlet to the outlet passes through and/or around a major part of the coil.

3. Apparatus according to Claim 1, wherein said first heat exchanger comprises a tank containing a close-wound heat exchange coil, said coil and tank are elongate in cross-section, a fluid inlet is provided at one end and side of the tank, and a fluid outlet is provided at the same end but opposite side of the tank.

4. Apparatus according to Claim 1 or 3, wherein said second heat exchanger comprises an elongate tank containing an elongate heat exchanger coil, a fluid inlet is provided at one end of the tank, and a fluid outlet is provided at an opposite end of the tank.

5. Apparatus according to Claim 4, wherein said second heat exchanger comprises a further heat exchange coil wound around said elongate coil with its axis substantially perpendicular thereto.

6. Apparatus according to Claim 4, wherein said second heat exchanger comprises a further heat exchange coil adjacent said elongate coil, both coils being closely wound adjacent the edges of the tank.

7. Apparatus according to Claim 5 or 6, wherein said coils of said second heat exchanger are adapted to carry respective products to be dispensed by said third means.

8. Apparatus according to any preceding claim, wherein said third means comprises at least one hand pump.

9. Apparatus according to any preceding claim, wherein said first heat exchanger comprises an inlet for said secondary heat exchange medium, which inlet comprises spray nozzle means.

10. Apparatus according to any preceding claim, wherein said first and second heat exchangers comprise respective reservoirs for said secondary heat exchange medium.

1 Apparatus according to Claim 10, including means for filling said reservoirs individually, thereby to charge a circuit for said secondary heat exchange medium.

1 2. Apparatus according to any preceding claim, wherein said primary heat exchange medium is a refrigerant and said secondary heat exchange medium is a coolant.

13. Apparatus according to Claim 11, including a compressor and a condenser for said refrigerant.

14. Apparatus according to Claim 13, wherein said compressor, condenser and first heat exchange unit are part of a portable refrigeration unit.

1 5. Apparatus according to any preceding claim, wherein the heat-exchange areas of said heat exchangers and the flow rates of said heat exchange media and product are such as to provide substantial uniformity of temperature between said heat exchange media at the output of said secondary heat exchange medium from said first heat exchanger and/or substantial uniformity of temperature between said secondary heat exchange medium and the product at the output of said secondary heat exchange medium from said second heat exchanger.

1 6. Apparatus according to any preceding claim, including a first thermostat adapted to control the flow of said primary heat exchange medium through said first heat exchanger, in response to the temperature of said secondary heat exchange medium at or adjacent the outlet thereof from the first heat exchanger.

1 7. Apparatus according to any preceding claim, including a second thermostat adapted to control the flow of said secondary heat exchange medium through said heat exchangers, in response to the temperature of said secondary heat exchange medium in the second heat exchanger.

1 8. Apparatus according to Claim 17, wherein said second thermostat is adapted to respond to an average temperature of the secondary heat exchange medium in the second heat exchanger.

1 9. Apparatus according to any preceding claim, wherein the mass of said secondary heat exchange medium is sufficiently small as to provide no appreciable heat store in the apparatus.

20. Apparatus according to any preceding claim, comprising a plurality of said second heat exchangers, each having a respective said second means for circulating the secondary heat exchange medium through both the first exchanger and the respective second heat exchanger.

21. Apparatus according to any preceding claim, wherein said third means is adapted to dispense a drink as said product.

22. Heat exchange apparatus substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

23. Heat exchange apparatus substantially as hereinbefore described with reference to Figure 1, together with Figure 2 and/or Figures 3 and 4 of the accompanying drawings.

24. A method of dispensing a drink, including the steps of cooling and dispensing the drink by means of apparatus according to any preceding claim.

25. A method according to Claim 24, wherein said drink is wine.

26. A method according to Claim 24, wherein said drink is beer.