JP2008533429A - Defroster for bottle cooler and method thereof - Google Patents

Abstract

  The bottle cooling system (20, 70, 100) has a compressor (22), a first heat exchanger (24), and a second heat exchanger (28). In the cooling operation mode, the second heat exchanger cools the contents in the internal space downstream of the first heat exchanger and upstream of the compressor. In the defrosting operation mode, the frozen material accumulated in the second heat exchanger is thawed using the refrigerant in the second heat exchanger.

Description

  Filed on March 18, 2005 and claims the benefit of US Patent Application No. 60 / 663,961, entitled “Defroster and Method for Bottle Coolers”, and disclosure of that patent application. Is a reference to this application. Co-pending application docket 5-258-WO entitled "High Pressure Side Pressure Control for Transcritical Vapor Compression System" and filed with this application on the same date discloses prior art and inventive cooling systems. The disclosure of said application is a reference to this application. This application discloses possible variations to the system.

  The present invention relates to refrigeration. More particularly, the present invention relates to a beverage cooler.

The CO ₂ bottle cooler utilizes a compressor, a gas cooler, an expansion device, and an evaporator that transfers thermal energy from the cold energy store to the hot energy sink. This transmission is achieved with the help of electrical energy input to the compressor. As the refrigerant passes through a low temperature heat exchanger (eg, an evaporator), the transfer of thermal energy from the internal air to the refrigerant is caused by the temperature difference between the outdoor air and the refrigerant. The fan keeps moving fresh air across the evaporator surface to maintain the temperature difference and evaporate the refrigerant. When the surface temperature of the evaporator falls below the dew point temperature of the wet air stream, water condenses on the fin surface. When the surface of the evaporator falls below the freezing temperature, water droplets condensed on the surface can freeze. A frost column then grows from the frozen water droplets and begins to block the air flow path through the evaporator fins. This shut-off increases the pressure drop due to the evaporator, which reduces the air flow. Due to the frost insulation effect and air flow blockage, the refrigerant temperature in the evaporator is lowered, which ultimately results in degradation of bottle cooler performance and a reduction in cooling capacity and COP. As a result, the defrost cycle must be started.

  In existing methods, the compressor and the fan for the higher heat exchanger (e.g., the condenser) are stopped (at least in the normal mode) while the evaporator fan is kept running. By circulating the air in the bottle cooler cabinet so as to pass through the evaporator, the frost on the coil can be heated. The temperature of the air in the cabinet (usually 3.3 ° C. (38 ° F.), or 2 ° C. to 4 ° C. (36 ° F. to 39 ° F.) to a greater extent) is the frost temperature (0 ° C. ( The defrosting process usually takes a long time because it is very close to 32 ° F)).

  When the bottle cooler is installed outdoors, an electric heater that normally heats the air in the cabinet is required to keep the beverage from freezing. Since the efficiency of the electric heater is at most 100%, the cost of heating the air in winter is very high.

  The bottle cooling system has means for switching the system to the second operation mode, and the refrigerant in the evaporator thaws the ice accumulated on the evaporator surface. The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

  FIG. 1 schematically illustrates a transcritical vapor compression system 20 for a bottle cooler. The system has a compressor 22, a first heat exchanger 24, an expansion device 26, and a second heat exchanger 28. The accumulator 30 is also disposed in the suction line portion of the refrigerant flow path 32 between the outlet of the second heat exchanger 28 and the inlet 34 of the compressor 22. The discharge line of the flow path 32 extends from the compressor outlet 36 to the inlet of the first heat exchanger 24. A further line connects the first heat exchanger outlet to the expander inlet and connects the expander outlet to the second heat exchanger inlet. A typical inflator 26 is an electronic inflator. An alternative device is disclosed in the docket 05-258-WO application indicated above.

  The heat exchangers 24 and 28 can each take the form of a refrigerant-air heat exchanger. Air flow across one or both of these heat exchangers can be forced. For example, one or more fans 40, 42 can deliver an air flow 44, 46 across the coils of the two heat exchangers. The system has a controller 50 that can be connected to one or both of the expansion device 26 and the compressor 22 to control their respective operations. The controller 50 can be configured to allow user input and / or can be configured to allow input from one or more sensors (eg, temperature sensors or pressure sensors). FIG. 1 shows a typical temperature sensor pair 52, 54 (eg, a thermocouple). The first temperature sensor 52 is arranged to measure the coil temperature of the second heat exchanger 28 (advantageously to measure the temperature of the air entering or leaving the heat exchanger. Or arranged to measure the saturation temperature of the refrigerant in the heat exchanger). The second temperature sensor 54 is arranged to measure the refrigerant temperature in the suction line.

  The first heat exchanger 24 can be disposed outside the refrigerated space of the bottle cooler. The second heat exchanger 28 can be disposed along the recirculation air flow path within or into the space.

  In the first mode of operation (eg, normal cooling mode), the compressor operates and the fans 40, 42 deliver their respective air streams 44, 46. The first heat exchanger 24 operates as a gas cooler that releases heat to the air stream 44 to cool the refrigerant passing through the first heat exchanger. Since the refrigerant expands while passing through the expansion device 26, the temperature further decreases. The second heat exchanger 28 operates as an evaporator to cool the air stream 46 and thus cool the chilled space of the bottle cooler. During normal operation, frost may accumulate on the coil surface of the second heat exchanger 28.

  In the second (defrosting) operation mode, the first fan 40 is stopped and the extraction of heat from the refrigerant in the first heat exchanger 24 is reduced. As a result, the refrigerant entering the second heat exchanger 28 becomes higher than 0 ° C. Therefore, this refrigerant is effective for defrosting the second heat exchanger. Furthermore, the fan 42 continues to move. As long as the air in the beverage cooler is above 0 ° C., the air flow 46 further facilitates defrosting of the second heat exchanger 28. If the expansion device 26 is controllable during the defrost mode, the expansion device can be opened to further increase the opening size to prevent overpressure in the high pressure portion of the system.

  The need for defrosting can be determined in various ways. In one embodiment, a timer (eg, included in the controller) is used and the system switches to defrost mode after a predetermined period of time has elapsed. When a more complicated controller is used, a single temperature sensor or a combination of temperature sensors can be used. For example, (1) the first temperature measured by the temperature sensor 52 is less than a first predetermined value (in this case, there is a possibility that frost is formed by distinguishing a potential frosted state from a pull-down state) For example, the air temperature is 40 ° F. or the coil temperature is 33 ° F.) (2) The difference between the second temperature measured by the temperature sensor 54 and the first temperature is the second temperature. If the value is exceeded, the evaporator can be considered frosted and can enter defrost mode.

  The system can be switched again from the defrost mode to the cooling mode in a similar manner. One example is a fixed time formula. Detected state (for example, if one output of temperature sensor 52 and temperature sensor 54 exceeds a third predetermined value, for example, 40 ° F. for air temperature or 35 ° F. for coil temperature) .

  FIG. 2 shows another system 70 in which the refrigerant flow path 72 includes first and second segment / diversion flow paths 74, 76 between the compressor outlet 36 and the inlet of the second heat exchanger 28. . The first shunt channel 74 may include the first heat exchanger 24 and the expansion device 26 in a manner similar to the first system 20. The second branch path 76 includes a switching valve 78. The switching valve 78 can also be controlled by the controller 50 (not shown in this and the remaining embodiments).

  In the first (cooling) mode of operation, the switching valve 78 is closed and the operation is the same as in the first mode of the system 20. In the second (defrosting) mode, the switching valve 78 opens and at least a portion of the compressed refrigerant bypasses the first shunt channel 74, thereby (with the fan 40 stopped) The cooling effect provided by one heat exchanger 24 and the expansion device 26 is weakened. There is also some flow through the first shunt 74. However, the first heat exchanger 24 and the expansion device 26 can be relatively restricted so that the majority of the system flow flows along the second shunt 76.

  Due to the refrigerant bypass along the second shunt path 76, the final temperature of the refrigerant entering the second heat exchanger 28 in the defrost mode of the system 70 is greater than in the defrost mode of the system 20. Also gets higher.

  The heating capacity of the system during the defrost mode is basically equal to the input power to the compressor. The input power to the compressor has a correlation with the discharge pressure of the compressor. In order to maximize the heating capacity, the input power should be maximized and therefore the discharge pressure should be as high as possible without causing an overpressure. In this way, the amount of input power, and thus the heating capacity, is maximized and the defrosting time is minimized. Minimizing the defrost time allows the system to exit the defrost mode and quickly return to the cooling mode, minimizing temperature fluctuations in the product stored in the cooler.

  FIG. 3 is a pressure-enthalpy diagram of the defrost cycle of the system 70. The refrigerant flow path has a first section 90 that passes through the compressor. At the time of this section 90, both the pressure and the enthalpy increase to the point 91 due to the input of mechanical energy. The second section 92 corresponds to a refrigerant flow path that passes through the second branch flow path 76 and the switching valve 78. Preferably, the second section 92 ends with approximately an isenthalpy change at the point 93 where the switching valve 78 operates as an expansion device and the pressure drops. A third section 94 from the pressure drop point 93 represents an essentially constant pressure flow path through the second heat exchanger 28 and releases heat to melt the frozen mass. The illustrated third section 94 returns to the origin 95 where the enthalpy has decreased, where the first section 90 begins again. In the illustrated illustration, the origin 95 (the point at which enthalpy and pressure are minimum) is on or near the saturated vapor line 96 that separates the gas-liquid mixing region 97 (“vapor dome”) and the gas region 98. In the alternative, the cycle occurs in the gas region 98 completely away from the vapor dome. In yet another possible situation, part of the cycle may be along the steam dome or within the steam dome.

Another alternative is to add a valve (eg, a four-way valve) that reverses the flow. This is particularly useful for bottle coolers installed outdoors. During summer, when cooling is required, the CO ₂ bottle cooler operates as a cooling device to lower the air temperature in the cabinet. In winter, the four-way valve is activated to reverse the flow and operate the bottle cooler as a heat pump to supply heat to the air in the cabinet. Since the efficiency (or COP) of the heat pump is always much higher than 100%, the operating costs for heating the air are greatly reduced. This heat pump mode of operation can also be used to defrost the evaporator coil.

  FIG. 4 shows a system 100 in which the flow reversal valve 102 has a flow reversal valve element 104 with two different flow paths. A typical element is a rotating element. FIG. 4 shows the valve element 104 oriented in the first (cooling) mode.

  FIG. 5 shows the valve element 104 oriented to be in the second (defrost or heat pump) mode. The valve 102 connects the compressor loop 110 of the refrigerant flow path to the main loop 112. The heat exchangers 24, 28 and the expansion device 26 are arranged along the main loop 112. In both modes, the flow along the compressor loop 110 is in the same direction. The valve serves to reverse the flow along the main loop 112. In the defrost mode, the second heat exchanger 28 operates as a gas cooler. The refrigerant gas passing through the second heat exchanger 28 is particularly effective for melting frost. The first heat exchanger 24 operates as an evaporator. In the defrost mode, the expansion device 26 adjusts the pressure in the second heat exchanger 28.

  A particular area for implementing the present invention is in a bottle cooler, which must be able to be placed outdoors (with large variations in ambient temperature) or must have the ability to be placed outdoors. Including. FIG. 6 shows an exemplary cooler 200 having a removable cassette 202 containing a refrigerant and air treatment system. A typical cassette 202 is attached to a compartment of the base 204 that constitutes the housing. The housing has an interior space 206 between the left and right walls, the rear wall / duct 216, the top wall / duct 218, the front door 220, and the base compartment. Inside, there is a vertically arranged shelf 222 that houses beverage containers 224.

  A typical cassette 202 draws airflow 44 from the front grid of base 224 and exhausts airflow 44 from the back of the base. The cassette can be pulled out from the front of the base by removing or opening the grid. A typical cassette delivers airflow 46 to a recirculation flow path through interior 206 via rear duct 210 and upper duct 218.

  FIG. 7 shows a typical cassette 202 in more detail. The heat exchanger 28 is disposed in a housing 240 defined by the heat insulating wall 242. The heat exchanger 28 is largely located in the upper rear quadrant of the cassette and is shown directed to send the air flow 46 generally rearward, the air flow being upward after leaving the heat exchanger. And discharged from the rear portion of the upper end of the cassette. Drain 250 can pass through the bottom of wall 242 and send condensed water from stream 46 to drain pan 252. Accumulated water 254 is seen in pan 252. The pan 252 is along an air duct 256 that passes a stream 44 downstream of the heat exchanger 24. By allowing the accumulated water 254 to come into contact with the heated air in the flow 44, evaporation can be promoted.

  One or more embodiments of the present invention have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of the invention. For example, when implemented as a remanufacturing of an existing system or a reorganization of an existing system configuration, the details of the existing configuration may affect the implementation details. Accordingly, other embodiments are within the scope of the following claims.

It is a schematic diagram of a first CO ₂ bottle cooler. FIG. ₂ is a schematic view of a first alternative CO ₂ bottle cooler. FIG. 3 is a pressure-enthalpy diagram of a defrost cycle in the CO ₂ bottle cooler of FIG. 2 in a defrost mode. FIG. 6 is a schematic diagram of a _second alternative CO ₂ bottle cooler in cooling mode. It is a schematic diagram of a CO ₂ bottle cooler of FIG. 4 in the defrost mode. It is a schematic side view of the display case bottle cooler containing a refrigerant | coolant and an air management cassette. FIG. 4 is a diagram of a refrigerant and air management cassette.

Claims (15)

A compressor (22) for delivering refrigerant along the flow path (32, 72, 100, 112) in at least a first mode of system operation;
A first heat exchanger (24) along the flow path (32, 72, 100, 112) downstream of the compressor (22) in the first mode;
A second heat exchanger for cooling the contents in the internal space of the system along the flow path (32, 72, 100, 112) upstream of the compressor (22) in the first mode. 28)
Means (50, 78, 102) for thawing the frozen matter accumulated in the second heat exchanger using the refrigerant in the second heat exchanger;
Cooling system (20, 70, 100).   The means moves the first fan (40) to blow a first air flow (44) across the first heat exchanger in the first mode, and in the second mode, A controller (50) programmed or configured to stop the first fan (40), raise the temperature of the refrigerant through the second heat exchanger, and thaw the frozen material. The system according to claim 1.   The means includes a bypass flow from a first position along the flow path between the compressor and the first heat exchanger to a second position between the expansion device and the second heat exchanger. A valve (78) along the path, the valve being openable to switch the system to a bypass mode, in which at least a portion of the compressor outlet flow is in the bypass flow path A system (70) according to claim 1, characterized in that the system proceeds to the second heat exchanger along the line and heats the second heat exchanger by a sufficient amount to thaw the frozen material. ).   The means comprises a reversing valve (102) operable to switch the system to a second mode, in which the first heat exchanger (24) and the second heat The system (100) of claim 1, wherein the flow through the exchanger (28) is reversed.   2. The means according to claim 1, further comprising means for heating the internal space of the cooler to prevent the contents from freezing when the external temperature falls below a threshold value. system.   The system according to claim 1, wherein the system is an externally powered built-in beverage cooler placed outdoors.   The first and second heat exchangers (24, 28) and the compressor (22) are removable as a unit from the system housing without having to empty the contents of the system in advance. The system of claim 1. The refrigerant is largely composed of CO _2,
The system of claim 1, wherein the first and second heat exchangers (24, 28) are refrigerant-air heat exchangers. The refrigerant consists essentially of CO _2,
The first and second heat exchangers (24, 28) each have an associated fan (40, 40).
42) a refrigerant-air heat exchanger, wherein the first mode air flow (44) across the first heat exchanger (24) is an external flow and the second heat exchanger The system of claim 1, wherein the first mode air flow (46) across (28) is a recirculating internal air flow.   The system according to claim 1, wherein the system is used with the contents including a plurality of beverage containers having a capacity of 0.3 to 4.0 liters. A vending machine that operates with cash,
A display case with a transparent door at the front and a closed rear,
A cooler box to take in and out from the top,
The system of claim 10, wherein the system is selected from the group consisting of: A method of operating the cooling system (20, 70, 100),
Activating the compressor (22) to compress the refrigerant and pump the refrigerant along the flow path (32, 72, 100, 112) in at least a first mode of system operation;
Removing heat from the refrigerant in the first heat exchanger (24) along the flow path (32, 72, 100, 112) downstream of the compressor (22) in the first mode;
In the first mode, a second heat exchange along the flow path (32, 72, 100, 112) upstream of the compressor (22) to cool the contents in the internal space of the system. Heat is absorbed by the refrigerant in the vessel (28),
An operation method comprising thawing frozen material accumulated in the second heat exchanger using a refrigerant in the second heat exchanger in a second operation mode. The transition between the first mode and the second mode is:
In the first mode, the first fan (40) is moved to blow a first air flow (44) across the first heat exchanger, and in the second mode, the first The controller (50) is programmed or configured to stop the fan (40) of the machine, raise the temperature of the refrigerant passing through the second heat exchanger, and thaw the frozen material. The driving method according to claim 12. The transition between the first mode and the second mode is:
Along the bypass flow path from a first position along the flow path between the compressor and the first heat exchanger to a second position between the expansion device and the second heat exchanger. Performed by a valve (78), which is opened to switch the system to the second mode, in which at least a portion of the compressor outlet flow is along the bypass flow path. 13. The operation method according to claim 12, wherein the operation proceeds to the second heat exchanger, and the second heat exchanger is heated with a sufficient amount to thaw the frozen material. The transition between the first mode and the second mode is:
Performed by a reversing valve (102) that operates to switch the system to the second mode, in which the first heat exchanger (24) and the second heat exchanger (28) 13. The method according to claim 12, wherein the flow through is reversed.

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