The present invention relates to refrigeration systems, and in particular to refrigeration systems for beverage dispensers in which a controller variably adjusts temperature cut-in and cut-out set temperature points for a compressor in accordance with demands for beverage chilling.
Depending upon the cooling load a refrigeration system is required to chill, the cooling demand placed on the system can vary widely. For example, when the refrigeration system serves the chilling requirements of a beverage dispenser, customer demand for beverages can vary from no drinks dispensed per minute to as many as 3 or 4 or more drinks dispensed per minute. This volatile variation in customer demand results in a broad range of cooling load requirements for the refrigeration system. When no beverages are being dispensed, the maintenance cooling load of a beverage dispenser can be as low as about 1500 Btu/hr. At the other extreme and during periods of high drink draw rates, cooling requirements can exceed 18,000 Btu/hr.
On-off operation of a compressor of a refrigeration system for a beverage dispenser is conventionally controlled by fixed temperature set-points that define a permissible range of beverage temperatures, ideally so that the beverage does not get either too warm or too cold and so that the refrigeration system compressor is not cycled on/off excessively. One set-point represents a maximum upper temperature that the beverage is permitted to reach before being chilled and the other set-point defines a minimum lower temperature of the beverage to be dispensed. When the refrigeration system compressor is off, the upper set-point is that temperature to which the beverage is allowed to warm before the compressor is cut-in or turned on to chill the beverage and reduce its temperature. The lower set-point is then that temperature to which the beverage is chilled before the compressor is cut-out or turned off. One problem with this technique is that it is not energy efficient. To conserve energy, it would be advantageous if beverage temperatures were allowed to be warmer during non-business hours than during business hours, but that cannot be accomplished with fixed upper and lower set-point temperatures. Another problem with the conventional approach is that fixed beverage temperature set-points constrain the refrigeration system compressor to operation between fixed cut-in and cut-out temperatures, irrespective of whether there are minimum or maximum cooling load demands being placed on the system. Consequently, when there is a minimum cooling load demand the refrigeration system cannot operate in a mode to conserve energy, and when there is a maximum cooling load demand the system cannot operate at an increased capacity to ensure that beverages are always properly chilled.
A primary object of the present invention is to provide a variable differential and offset control for refrigeration systems for beverage dispensers, which variably adjusts the sensed beverage temperature set-points at which a refrigeration system compressor is cut-in and cut-out and the temperature differential between the set points in accordance with changes in chilling demands placed on the refrigeration system by the beverage dispenser.
In accordance with the invention, a beverage dispensing system comprises a beverage dispenser; means for delivering beverage to the beverage dispenser; a refrigeration system having a compressor and an evaporator heat transfer coupled to beverage to be chilled for dispensing by the beverage dispenser, the compressor having cut-in and cut-out beverage temperature set-points; means for sensing the amount of chilling required to be provided by the refrigeration system to chill beverage to be dispensed by the beverage dispenser; and a controller coupled to the sensing means and the refrigeration system for adjusting the value of at least one of the compressor cut-in and cut-out beverage temperature set-points in accordance with the sensed amount of chilling required to be provided by the refrigeration system to chill beverage to be dispensed by the beverage dispenser.
In various embodiments of the beverage dispensing system, the controller adjusts at least one of the cut-in and cut-out set-points to provide the refrigeration system with a chilling capacity that is in accordance with the sensed amount of chilling required to be provided by the refrigeration system; the sensing means includes means for sensing the temperature of beverage to be chilled and that is being chilled by the refrigeration system; the sensing means includes means for sensing the amount of beverage delivered to the beverage dispenser; the controller adjusts at least one of the refrigeration system compressor cut-in and cut-out set-points to provide a chilling capacity of the refrigeration system that decreases on/off cycles of the refrigeration system; and the controller variably adjusts the refrigeration system compressor cut-in and cut-out set-points by changing a beverage temperature differential between the cut-in and cut-out set-points.
The invention also provides a method of operating a beverage dispensing system comprising a beverage dispenser having a beverage dispensing valve and a refrigeration system having a compressor and an evaporator heat transfer coupled to beverage to be chilled for dispensing by the beverage dispenser valve, the compressor having cut-in and cut-out beverage temperature set-points and the method comprising the steps of delivering beverage along a flow path to and through the beverage dispenser to the beverage dispensing valve; sensing the amount of chilling required to be provided by the refrigeration system to chill beverage to be dispensed by the beverage dispensing valve; and adjusting the temperature value of at least one of the compressor cut-in and cut-out set-points in accordance with the sensed amount of chilling required to be provided by the refrigeration system to chill beverage.
According to various embodiments of the method, the adjusting step adjusts both the cut-in and the cut-out set-point; the sensing step includes sensing the temperature of beverage at one or more points along the flow path; the sensing step includes sensing the amount of beverage delivered to the beverage dispenser; the adjusting step adjusts the temperature value of at least one of the compressor cut-in and cut-out set-points to provide a chilling capacity of the refrigeration system that decreases on/off cycles of the refrigeration system; and the adjusting step adjusts the refrigeration system compressor cut-in and cut-out set-points by changing a beverage temperature differential between the set-points.
Conventional refrigeration systems for beverage dispensers normally operate with fixed value set-points that define upper and lower sensed beverage temperatures that are used to control cut-in and cut-out of a compressor of the refrigeration system. The arrangement is such that upon sensed beverage temperature increasing to a pre-selected maximum, the compressor cut-in or is turned on to operate the refrigeration system to chill the beverage. The refrigeration system then continues to chill the beverage until sensed beverage temperature decreases to a pre-selected minimum, at which point the compressor is cut-out or turned off to terminate chilling of the beverage, whereupon the cycle is repeated. Since in conventional refrigeration systems cut-in and cut-out beverage temperatures have pre-selected fixed values and remain unchanged for all the various cooling demands placed on the refrigeration system by the beverage dispenser, the refrigeration systems are not able to efficiently respond to changing cooling load requirements of beverage dispensers, either by decreasing capacity to conserve energy when a beverage dispenser is idle or by increasing capacity to satisfy an increased cooling load demand when drink draw rates increase.
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In overcoming the aforementioned disadvantages of conventional refrigeration systems, the invention provides a variable differential and offset control for a refrigeration system for a beverage dispenser, in which cut-in and cut-out beverage temperature set-points and the temperature differential between the set-points are variably controlled and changed based upon user input. If the beverage dispenser is frequently operated to dispense beverages, the set-points and temperature differential can be changed to lower values to operate the refrigeration system sooner and more continuously, i.e., to decrease the beverage temperature at which the refrigeration system compressor is cut-in and cut-out. If drink dispensing is not occurring, such as during an overnight idle period of the beverage dispenser, the temperature differential and set-points are changed to higher default values to increase the temperatures at which the refrigeration system compressor cuts-in and cuts-out, which conserves the energy required to operate the refrigeration system and improves the reliability of the system by minimizing wear and tear associated with compressor on/off cycles.
The variable temperature differential and offset control of the invention provides for utilization of increased refrigeration system capacity when called for by high drink dispense rates and decreased refrigeration system capacity when there are low drink draw rates or idle conditions of the beverage dispenser. This is accomplished by varying the refrigeration system temperature set-points in accordance with beverage dispense demands, and in particular in accordance with changing demands for beverage chilling as are placed on the refrigeration system by changing drink draw rates and temperatures of beverages being delivered to the beverage dispenser from supplies thereof. The control system provides for a refrigeration system to have an increased capacity when needed, yet allows the refrigeration system to have a lower capacity and to maintain warmer beverage temperatures during periods of low usage of the beverage dispenser or when the dispenser is idle or in standby mode, such as during overnight periods.
In accordance with the invention, the beverage dispensing apparatus 20 advantageously embodies a variable temperature differential and offset control implemented by a programmable controller 38. The controller variably adjusts one or both of the refrigeration system set-points, i.e., one or both of the beverage temperatures at which the refrigeration system compressor is cut-in and cut-out, in accordance with changing chilling demands placed on the refrigeration system 22 by the beverage dispenser 24, and/or that are anticipated to be placed on the refrigeration system by the beverage dispenser. Actual changes in chilling demand may be sensed by any suitable means, such as by sensing beverage temperatures with temperature sensing devices such as a thermocouple 40 that detects the temperature of beverage incoming to the beverage dispenser 24 from the beverage supplies 26 and a thermocouple 42 that detects the temperature to which beverage has been chilled by the refrigeration system. Alternatively and/or additionally, the chilling load placed on the refrigeration system can be monitored by sensing drink draw rates and the size of drinks drawn. Where beverage temperature sensing is used to determine the chilling load placed on the refrigeration system, then based upon the difference between incoming and chilled beverage temperatures and/or a change in the difference between incoming and chilled beverage temperatures, the controller can determine the chilling load being placed on the refrigeration system and establish appropriate set-points, or cut-in and cut-out beverage temperatures, for the refrigeration system compressor, in a manner to adjust refrigeration system capacity to be in accordance with the chilling demand to be met, so that beverage is brought to and maintained at a proper temperature for dispensing. Alternatively or additionally, the controller can sense the occurrence, frequency and size of drinks dispensed and make appropriate adjustments to compressor set-points based upon a calculated amount of chilling output from the refrigeration system that will be required to properly chill the relatively warm replacement beverage incoming to the beverage dispenser 24 from the beverage supplies 26. Thus, based upon the value of the inputs it receives, the controller 38 determines the appropriate adjustment to be made to the beverage temperature set-points for cut-in and cut-out of the refrigeration system compressor, which determination can be made by implementation of an appropriate algorithm or through use of a look-up table.
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During periods of mid usage of the beverage dispenser 24, which mid usage is greater than low usage, the compressor cut-in set-point is reduced to the mid variable beverage temperature and the compressor cut-out set-point remains at the normal beverage temperature. By reducing the compressor cut-in point to the mid variable beverage temperature, refrigeration system capacity is increased and the average temperature of the beverage is reduced, so that when the compressor is off during a mid usage period, the beverage is not permitted to warm to a point that an insufficiently chilled drink might be drawn. Because the mid cut-in set-point is variable, it can be increased or decreased depending upon where the actual drink draw rate falls within the range of drink draw rates considered as mid usage. During mid usage periods, the time constant of the refrigeration system 22 decreases and refrigeration system capacity increases.
During periods approaching continuous usage of the beverage dispenser 24, compressor cut-in remains at the mid variable cut-in temperature and compressor cut-out is reduced to the extreme usage cut-out temperature. By reducing the compressor cut-out point to the extreme usage beverage temperature, refrigeration system capacity is increased and average beverage temperature is decreased relative to the refrigeration system capacity and average beverage temperature that exist at the mid usage level. The apparatus 20 is thereby better able to dispense properly chilled beverages, even at an increased and almost continuous drink draw rate. Because the mid compressor cut-in temperature is variable, it can be increased or decreased depending upon where the actual drink draw rate falls within the range of drink draw rates considered as approaching continuous, so that refrigeration system capacity can be better matched to the actual chilling demand then being placed on the refrigeration system. There is, however, a maximum temperature for the mid variable cut-in that cannot be exceeded in order to avoid the potential of beverage temperature increasing to a point where an insufficiently chilled drink could be served.
During periods of extreme high usage of the beverage dispenser 24, the compressor cut-in point is reduced to the extreme usage cut-in beverage temperature and the compressor cut-out point remains at the extreme usage cut-out beverage temperature. By reducing the compressor cut-in point to the extreme usage beverage temperature, the beverage is chilled to a low temperature and is not allowed to warm significantly, so that refrigeration system capacity and average beverage temperature are reduced relative to refrigeration system capacity and average beverage temperature that exist at the continuous usage level. This serves to enhance rapid chilling of relatively warm replacement beverage delivered to the beverage dispenser 24 from the beverage supplies 26 as beverages are dispensed at a high drink draw rate.
During periods when the beverage dispenser 24 is on standby and not being used, such as during overnight periods when it is idle, it is not necessary to maintain as low an average beverage temperature as is maintained during periods when drink dispensing occurs. However, the beverage must be kept sufficiently cold to avoid health concerns arising from spoilage. Accordingly, during such periods compressor cut-in is set at the high variable beverage temperature and compressor cut-out is increased to the standby beverage temperature, which keeps the beverage cold enough to prevent spoilage yet warm enough that compressor usage is limited to conserve energy.
Where the beverage to be chilled is a sugared beverage, representative temperatures for the various cut-in and cut-out set-points can be in the range of +/−1° F. of those shown in the following table, thereby to prevent overlap of the temperatures:
It is to be understood, however, that practice of the invention is not limited to use of such temperatures for cut-in and cut-out set points, and that the mentioned +/−1° F. range of such temperatures can be increased if the set-point temperatures are selected such that overlap of the set-points would not occur. In particular, the set-point temperatures can have various different values depending upon the particular application in which they will be applied for controlling a machine.
Chilling of relatively warm beverage delivered from the beverage supplies 26 to the beverage dispenser 24 is accomplished by heat transferring coupling an evaporator of the refrigeration system 22 to the beverage in any of numerous manners well known to those skilled in the art. For the purpose of describing the present invention, beverage chilling can occur through use of the evaporator 30 of
The invention provides an improved beverage dispensing apparatus in which a refrigeration system for a beverage dispenser has its compressor controlled by variable cut-in and cut-out set-points having values determined in accordance with sensed beverage temperatures and/or drink dispense rates. The cut-in and cut-out set-points are, chosen to provide a variable chilling capacity and efficient operation of the refrigeration system, such that the chilling capacity is closely matched to the chilling demand of the beverage dispenser to ensure that a continuous supply of properly chilled beverage is always available for service. In essence, operation of the beverage dispensing apparatus is adjusted, as required, based on user inputs.
Variable differential control of the cut-in and cut-out set-points of the refrigeration system 22 allows customer behavior to impact drink dispensing apparatus performance. As customer demand for product dispense increases, the controller 38 runs the refrigeration system more often and at an increased capacity. This is achieved by varying the compressor run time with a differential control algorithm that is only utilized when customers demand drinks be dispensed. As the demand for drinks lapses, such as during overnight hours, the controller operates the refrigeration system less often and at a decreased capacity by reverting to a differential control scheme that prevents the drink dispenser 24 from over-refrigerating the product.
The invention embodies a control scheme for saving energy by reducing overall run time as lower drink demands dictate. With lower drink demand there is lower energy consumption and attendant increased reliability of the refrigeration system due to a reduction in on/off cycles of refrigeration system components. The controller 38 allows the refrigeration system 22 to remain in a standby state until customers demand drink dispensing. The standby state allows the beverage dispensing apparatus 20 to be ready to dispense chilled drinks when demand is increased as well as to keep beverages cool enough to meet product and quality specifications without creating reliability issues for the product.
In practice of the invention, the temperature of a beverage or juice is variably controlled as it is dispensed. This is accomplished with a beverage dispensing apparatus that generally embodies a refrigeration system; a refrigeration system controller; a means for demanding beverage dispensing (e.g., a push-button, lever, etc.); thermocouples heat transfer coupled to the beverage at various locations for sensing beverage temperature and for providing beverage temperature feedback to the refrigeration system controller; a power supply; and system logic for the controller to vary refrigeration system capacity by controlling the operating profile or set-points for the refrigeration system compressor, as required by the chilling demand of the dispensing apparatus. In essence, the refrigeration system controller varies refrigeration system capacity by changing the cut-in and cut-out set-points of the refrigeration system compressor as deemed necessary by the demand for beverages. In changing the compressor cut-in and cut-out set-points, the controller not only changes the beverage temperatures for the cut-in and cut-out set-points, but also changes the differential between the cut-in and cut-out set-points if and as necessary as required by the demand being placed on the apparatus.
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.
This application is a U.S. National Stage application of international application No. PCT/US10/002831, filed Oct. 25, 2010, under the Patent Cooperation Treaty, which United States Patent Cooperation Treaty (PCT) Application claims priority and filing date from U.S. provisional application Ser. No. 61/279,912, filed Oct. 28, 2009.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2010/002831 | 10/25/2010 | WO | 00 | 4/23/2012 |
Publishing Document | Publishing Date | Country | Kind |
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WO2011/053347 | 5/5/2011 | WO | A |
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