Multiple barrel frozen product dispenser
A frozen product dispenser is characterized by at least two product freeze barrels for receiving product therein and for freezing the product for dispensing, and a refrigeration system for chilling the at least two barrels. The refrigeration system has at least two evaporators for and heat transfer coupled to each barrel, separate and controllable expansion valves each having an outlet coupled to an inlet to an inlet to an associated one of the evaporators, at least two compressors having outlets coupled to inlets to the expansion valves and inlets coupled to outlets from the evaporators, and at least one condenser in fluid circuit between outlets from the compressors and inlets to the expansion valves. The refrigeration system is controllable to selectively operate one or more of the compressors and one or more of the expansion valves in accordance with the cooling requirements of the barrels to provide an improved turndown ratio for improvements in efficiency of operation of the refrigeration system in response to changing cooling load requirements of the product barrels.
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This application claims benefit of provisional patent application Ser. No. 60/799,818, filed May 12, 2006.
FIELD OF THE INVENTIONThe present invention relates to frozen product dispensers, and in particular to a frozen product dispenser having an improved refrigeration system that efficiently handles large variations in cooling load demands of a plurality of frozen product barrels of the dispenser.
BACKGROUND OF THE INVENTION The load requirements of frozen beverage product dispensers are highly variable, since customer demand for beverages can vary from no drinks dispensed per minute to as many as 3 or 4 or more drinks served per minute. This volatile variation in customer demand results in a very broad range of cooling load requirements for a typical frozen product dispenser, such for example as is shown by the chart of
As is known, conventional frozen product dispensers utilize a compressor that delivers refrigerant through a condenser to one or more expansion valves, each of controls delivery of refrigerant to an associated evaporator cooling coil that is thermally coupled to an associated product barrel in order to chill the product barrel to freeze product in the barrel. To accommodate various cooling load requirements of the product barrels, the expansion valves advantageously are variably controlled, such that as load requirements for an evaporator coil change due to changing customer demands, the expansion valve supplying refrigerant to the evaporator changes to a more appropriate refrigerant flow metering position. The idea is to adjust the expansion valve so as to match the cooling capability of the evaporator, based upon refrigerant flow to the evaporator, more closely to the dynamically changing cooling load requirements of the product barrel that is being chilled by the evaporator. However, fixed speed compressors of a type normally used for frozen product dispensers are not readily able to accommodate changes in cooling load requirements and are best suited to provide refrigerant flow at a certain rate, despite changes in the cooling load. Refrigeration system balance therefore becomes disturbed as the expansion valves are adjusted to meet changing cooling load requirements, resulting in saturated evaporator temperature dropping as cooling load requirements decrease, rising as cooling load requirements increase, and generally poor control over the temperature of the evaporator. In addition, when cooling load requirements decrease, cooling of product in the barrel is quickly satisfied and the compressor must be cycled off. In consequence, where the compressor is not matched with the cooling load, during periods of low product demand the compressor will cycle on/off excessively and the system will operate less efficiently and use more energy than would otherwise be required.
Various known design strategies can be employed to better balance the refrigeration system of frozen product dispensers. One such strategy contemplates using hot-gas bypass to create a “false load” for the compressor, but often there are reasons involving cost and/or complexity of design that rule out using a hot-gas bypass technique. Another strategy involves modulation of compressor pumping capacity to better match compressor cooling capacity to the actual cooling load requirements of the product barrels, but while compressor modulation can be provided by mechanical means in larger capacity compressors, doing so can be cost prohibitive when using smaller compressors of a size as are usually employed in frozen product dispensers.
OBJECT OF THE INVENTIONA primary object of the present invention is to provide a frozen product dispenser having an improved refrigeration system that chills, and efficiently handles large variations in cooling load demands of a plurality of, frozen product barrels.
SUMMARY OF THE INVENTIONIn accordance with the present invention, there is provided a frozen product dispenser comprising a plurality of product freeze barrels for receiving liquid product and freezing the product for dispensing; and a refrigeration system for chilling the plurality of barrels to freeze liquid therein. The refrigeration system includes a plurality of evaporators, each heat transfer coupled to a respective one of the barrels; a plurality of variably controllable expansion valves each fluid coupled at an inlet to an inlet to an associated evaporator; at least two compressors having inlets fluid coupled to outlets from each evaporator; and at least one condenser in fluid circuit between outlets from the at least two compressors and inlets to the expansion valves.
In a contemplated embodiment of the invention, the plurality of product freeze barrels is two barrels, the plurality of evaporators is two evaporators, the at least two compressors are two compressors and the at least one condenser is one condenser, and further included is a control system for controlling operation of the compressors and expansion valves.
The invention also contemplates a method of making a frozen product, which comprises the steps of providing a plurality of product freeze barrels; introducing liquid product into the plurality of barrels; and chilling the plurality of barrels to freeze product therein. The chilling step comprises heat transfer coupling plurality of evaporators to each barrel; providing a separate and variably controllable expansion valve at an inlet to each evaporator; and providing refrigerant from at least two compressors through at least one condenser and the expansion valves to the evaporators to chill the plurality of barrels.
In a contemplated practice of the method, the providing step provides two product freeze barrels, the heat transfer coupling step comprises heat transfer coupling two evaporators to each barrel, the providing refrigerant step comprises providing refrigerant from two compressors through one condenser and the expansion valves to the evaporators, and included is the step of controlling operation of the compressors and the expansion valves.
The foregoing and other objects, advantages and features of the invention will become apparent upon a consideration of the following detailed description, when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The dispenser 50 is fluid coupled to a number of separate beverage component sources that may include first, second and third beverage syrup or flavor concentrate sources 52, 54 and 56, each of which may be a different flavor or brand of syrup or flavor concentrate. Each beverage component source 52, 54 and 56 may be individually supplied in a suitable container, such as in a bag-in-box or syrup tank, and has its output fluid coupled through an associated one of three flow metering device, such as metering pumps 58, 60 and 62, to a flow control device 64 that delivers the beverage components to frozen product barrels of the dispenser 50. The dispenser may also be fluid coupled to a source of water 66, such as potable water from a city main, as well as to a source of carbon dioxide gas 68 through a pressure regulator 70. The water source 66 is fluid coupled to the flow control device 64 through a metering pump 72 or other suitable flow metering device, whereby along with the metering devices 58, 60 and 62, selected ratios of water and beverage syrup(s) may be delivered to the flow control device 64.
Fluid outputs from the flow control device 64 are coupled to a plurality of expansion chambers 74 and 76 through fluid lines 78 and 80, each of which fluid line is for delivering beverage components to an associated product freeze barrel. The output from the CO2 regulator 70 is connected via a fluid line 82 with the fluid lines 78 and 80 to enable the introduction of CO2 gas into the beverage component fluid flows delivered into the lines 78 and 80 by the flow control device 64. The expansion chambers 74 and 76 are each fluid coupled to an inlet to an associated one of a plurality of freeze barrels 84 and 86 into which are delivered beverage components through associated fluid lines 78 and 80, and the expansion chambers operate in a well known manner to receive beverage product from their associated freeze barrels as the product expands in the barrels upon freezing. The expansion chambers may be of conventional design, and while the CO2 and water are shown as being separately delivered into the fluid lines 78 and 80, if desired a conventional carbonator tank can be employed to carbonate the water with CO2 for metered introduction into the flow control device 64. It is understood that while only two expansion chambers 74 and 76 and two product freeze barrels 84 and 86 are shown for convenience in describing the invention, a greater number of associated pairs of expansion chambers and freeze barrels may be used in practice of the invention, as will become apparent. As will be described in greater detail, the freeze barrels are encircled by and in heat transfer contact with evaporator circuits that chill the barrels to freeze beverage product components delivered into the barrels. It is also understood that while not specifically shown, electric motor driven scraper assemblies are provided for each freeze barrel to scrape frozen product off of the interior surfaces of the barrels for dispensing from associated product dispensing nozzles 88 and 89, and that the current draw of each electric motor is in accordance with the torque required to turn its scraper in its associated barrel and, therefore, that the current draw of the motor is representative of the state to which product its barrel is frozen. To the extent described, the frozen product dispenser 50 is generally conventional.
According to the invention, in improving upon conventional frozen product dispensers, the dispenser 50 utilizes a novel refrigeration system for chilling the product freeze barrels 84 and 86 in an efficient manner, even upon the occurrence of large variations in cooling load demands placed upon it by the barrels in response to significant and volatile changes in customer demand for frozen beverage products. As will be described, in the refrigeration system of the invention, and as compared to a conventional refrigeration system (see
One embodiment of refrigeration system contemplated by the invention for chilling the two freeze barrels 84 and 86 is shown in
The refrigeration system 90 includes two compressors 92 and 94, each of which may be either a fixed or variable speed compressor sized to have about one-half the capacity of a single compressor as would customarily be used in a conventional refrigeration system (see
As compared to the conventional refrigeration system 20 of
As an example of how the refrigeration system of the invention operates more efficiently in chilling freeze barrels of a frozen product machine, it is understood that in the conventional refrigeration system 20 of
On the other hand, in operation of the novel refrigeration system 90 of the invention, when the system is operating at 100% of cooling capacity, both compressors 92 and 94 are running and all of the expansion valves 102, 104, 106 and 108 are open to provide refrigerant flows to their associated evaporators 110, 112, 114 and 116 to chill the freeze barrels 84 and 86. However, should cooling load requirements of the barrels 84 and 86 decrease, such that 100% of cooling capacity is not required, one of the compressors 92 and 94 can be shut down and one of the expansion valves closed, so that the system then operates at 50% capacity, with the one running compressor providing refrigerant through three open expansion valves to their associated evaporators. Should cooling load requirements continue to decrease, two additional expansion valves can sequentially be closed until there no longer is a cooling load to be met and the second compressor is shut off. Each separate refrigeration circuit of
It is to be appreciated that the
While embodiments of the invention have been described in detail, various modifications and other embodiments thereof may be devised by one skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.
Claims
1. A frozen product dispenser, comprising:
- at least two product freeze barrels for receiving and chilling product for dispensing; and
- a refrigeration system for chilling said at least two barrels, said refrigeration system including a plurality of evaporators heat transfer coupled to associated ones of said at least two barrels with at least two evaporators per barrel for chilling said barrels, a plurality of controllable expansion valves each having an outlet coupled to an inlet to an associated one of said evaporators, at least two compressors having inlets coupled to outlets from said evaporators, and at least one condenser coupled between outlets from said at least two compressors and inlets to said expansion valves.
2. A frozen product dispenser as in claim 1, including a control system for sensing the chilling requirements of each of said at least two barrels and for controlling operation of said at least two compressors and said plurality of expansion valves to selectively operating one or more of said at least two compressors and one or more of said plurality of expansion valves to chill each of a selected one or more of said at least two barrels at rate in accordance with the sensed chilling requirements thereof.
3. A frozen product dispenser as in claim 1, wherein said at least two barrels are two barrels, said at least two evaporators per barrel are two evaporators per barrel, said at least two compressors are two compressors, and said at least one condenser is one condenser, and including a control system sensing the chilling requirements of each of said two barrels and for controlling operation of said two compressors and said expansion valves to selectively operate one or both of said compressors and one or more of said expansion valves to chill each of a selected one or both of said two barrels at a rate in accordance with the sensed chilling requirements thereof.
4. A frozen product dispenser as in claim 1, wherein said inlets to each of said compressors are coupled to said outlets from each of said evaporators, and said at least one condenser is coupled between said outlets from each of said at least two compressors and said inlets to each of said evaporators.
5. A frozen product dispenser as in claim 1, including a control system for operating said refrigeration system, said control system including means for sensing the state to which product in each of said at least two barrels is chilled, and means responsive to said sensing means to operate one or more of said compressors and one or more of said expansion valves to chill one or more of said evaporators to thereby chill each of one or more of said barrels at a rate selected in accordance with the sensed state to which product is chilled therein.
6. A refrigeration system for chilling product in at least two containers, said refrigeration system including a plurality of evaporators heat transfer coupled to associated ones of said containers with at least two evaporators per container for chilling product in said containers, a plurality of controllable expansion valves for said evaporators, each expansion valve coupled at an outlet therefrom to an inlet to an associated one of said evaporators, at least two compressors coupled at inlets thereto to outlets from said evaporators, and at least one condenser coupled between outlets from said compressors and inlets to said expansion valves.
7. A refrigeration system as in claim 6, including a control system for operating said refrigeration system, said control system including means for sensing the state to which product in each of said containers is chilled, and means responsive to said sensing means to operate one or more of said compressors and one or more of said expansion valves to deliver refrigerant to one or more of said evaporators to chill each of one or more of said containers at a rate selected in accordance with the sensed state to which product is chilled therein.
8. A method of operating a frozen product dispenser having at least two product freeze barrels for receiving and chilling product for dispensing, and a refrigeration system for chilling the at least two barrels, the refrigeration system including a plurality of evaporators heat transfer coupled to associated ones of the at least two barrels with at least two evaporators per barrel for chilling the barrels, a plurality of controllable expansion valves each having an outlet coupled to an inlet to an associated one of the evaporators, at least two compressors having inlets coupled to outlets from the evaporators, and at least one condenser coupled between outlets from the at least two compressors and inlets to the expansion valves, said method comprising the steps of:
- sensing the state to which product in each barrel is chilled; and
- in response said sensing step, operating one or more of the compressors and one or more of the expansion valves to chill one or more of the evaporators to thereby chill one or more of the barrels at a rate selected in accordance with the sensed state to which product is chilled therein.
9. A method of making a chilled product, comprising the steps of:
- introducing product into at least two containers; and
- chilling the at least two containers to chill the product therein,
- said chilling step comprises the steps of:
- heat transfer coupling a plurality of evaporators to the containers with at least two evaporators per container;
- coupling each of a plurality of controllable expansion valves to an inlet to an associated one of the evaporators; and
- delivering refrigerant from one or more of at least two compressors through at least one condenser and a selected one or more of the expansion valves to the associated evaporators to chill one or more of the containers.
10. A method according to claim 9, including the step of sensing the state to which product in each container is chilled, and controlling said delivering step in accordance with said sensing step to chill only those containers in which product is chilled to less than a selected state.
Type: Application
Filed: May 14, 2007
Publication Date: Jan 10, 2008
Applicant:
Inventors: David Gist (Grayslake, IL), Kyle Elsom (Batavia, IL), Gregory Billman (Hoffman Estates, IL), Nikolay Popov (Warrenville, IL), Santhosh Kumar (Woodridge, IL), Daniel Leaver (Westmont, IL)
Application Number: 11/803,264
International Classification: F25C 1/14 (20060101); F25B 39/02 (20060101);