Refrigeration systems having prescriptive refrigerant flow control

A method of operating a refrigeration system for a frozen product dispenser having a freeze barrel from which frozen product is periodically dispensed and into which relatively warm product if flow to replace dispensed product, whereby the freeze barrel places on the refrigeration system a heat load that varies in accordance with the quantity and temperature of relatively warm replacement product periodically flowed into the freeze barrel, said method comprising the steps of:

• heat exchange coupling an evaporator to the freeze barrel to chill product in the freeze barrel to within a selected temperature range;
• metering refrigerant through an adjustable expansion valve to the evaporator;
• delivering refrigerant to the expansion vale with a variable speed compressor;
• sensing a chilling requirement placed on the refrigeration system by a flow of relatively warm product into the freeze barrel, that is to be provided by the refrigeration system in order for the refrigeration system to cool the product to within the selected temperature range;
• selecting, in response to performance of said sensing step, the duration of a time interval during and throughout which the refrigeration system is to provide the sensed chilling requirement;
• and
• operating the refrigeration system, in response to performance of said sensing and selecting steps, to control the speed of operation of the compressor to deliver refrigerant to the expansion valve, and to adjust the expansion valve to meter refrigerant to the evaporator, at flow rates such that the refrigeration system provides the sensed chilling requirement during and throughout the selected time interval;
• wherein said sensing step comprises the step of monitoring the quantity and temperature of relatively warm replacement product flowed into the freeze barrel and, in response to said monitoring step, determining the number of Btu's of cooling required to be provided by the refrigeration system to chill the relatively warm replaced product flowed into the freeze barrel, and thereby the product in the freeze barrel, to within the selected temperature range during the selected time interval.

A method of operating a refrigeration system for a frozen product dispenser having a freeze barrel from which frozen product is periodically dispensed and into which relatively warm product if flow to replace dispensed product, whereby the freeze barrel places on the refrigeration system a heat load that varies in accordance with the quantity and temperature of relatively warm replacement product periodically flowed into the freeze barrel, said method comprising the steps of:

• heat exchange coupling an evaporator to the freeze barrel to chill product in the freeze barrel to within a selected temperature range;
• metering refrigerant through an adjustable expansion valve to the evaporator;
• delivering refrigerant to the expansion vale with a variable speed compressor;
• sensing a chilling requirement placed on the refrigeration system by a flow of relatively warm product into the freeze barrel, that is to be provided by the refrigeration system in order for the refrigeration system to cool the product to within the selected temperature range;
• selecting, in response to performance of said sensing step, the duration of a time interval during and throughout which the refrigeration system is to provide the sensed chilling requirement;
• and
• operating the refrigeration system, in response to performance of said sensing and selecting steps, to control the speed of operation of the compressor to deliver refrigerant to the expansion valve, and to adjust the expansion valve to meter refrigerant to the evaporator, at flow rates such that the refrigeration system provides the sensed chilling requirement during and throughout the selected time interval;
• said sensing step comprising the steps of incrementing into a Btu counter, in response to a flow of relatively warm product into the freeze barrel, a count representative of the number of Btu's of chilling required to be provided by the refrigeration system to the freeze barrel in order to chill the product flowed into the freeze barrel, and thereby the product in the freeze barrel, to within the selected temperature range, and decrementing the count in the Btu counter, in response to chilling of product in the freeze barrel by the refrigeration system, by the number of Btu's of chilling provided by the refrigeration system to the freeze barrel, whereby the instantaneous count in the Btu counter is representative of the number of Btu's of cooling yet required to be provided by the refrigeration system to chill product in the freeze barrel to within the selected temperature range.

A method of operating a refrigeration system for a frozen product dispenser having a freeze barrel from which frozen product is periodically dispensed and into which relatively warm product if flow to replace dispensed product, whereby the freeze barrel places on the refrigeration system a heat load that varies in accordance with the quantity and temperature of relatively warm replacement product periodically flowed into the freeze barrel, said method comprising the steps of:

• heat exchange coupling an evaporator to the freeze barrel to chill product in the freeze barrel to within a selected temperature range;
• metering refrigerant through an adjustable expansion valve to the evaporator;
• delivering refrigerant to the expansion vale with a variable speed compressor;
• sensing a chilling requirement placed on the refrigeration system by a flow of relatively warm product into the freeze barrel, that is to be provided by the refrigeration system in order for the refrigeration system to cool the product to within the selected temperature range;
• selecting, in response to performance of said sensing step, the duration of a time interval during and throughout which the refrigeration system is to provide the sensed chilling requirement;
• and
• operating the refrigeration system, in response to performance of said sensing and selecting steps, to control the speed of operation of the compressor to deliver refrigerant to the expansion valve, and to adjust the expansion valve to meter refrigerant to the evaporator, at flow rates such that the refrigeration system provides the sensed chilling requirement during and throughout the selected time interval;
• wherein the sensing step comprises detecting the quantity and temperature of relatively warm product flowed into the freeze barrel, determining the number of Btu's of chilling required to be provided by the refrigeration system to chill product flowed into the freeze barrel, and thereby product in the freeze barrel, to within the selected temperature range, said selecting step selecting the duration of a time interval during and throughout which the refrigeration system is to provide the determined number of Btu's, and including the step of ascertaining the mass flow of refrigerant required to be metered by the expansion valve to the evaporator to provide the determined number of Btu's, said operating step adjusting the speed of the compressor and the metering rate of the expansion valve to deliver to the evaporator the ascertained mass flow of refrigerant during the selected time interval.