Abstract:
A refrigeration apparatus includes an air chiller including a fan, a storage enclosure defining a compartment, and a duct system. The air chiller blows chilled air into the duct system. The compartment has first and second openings, each of which is coupled to the duct system. Chilled air enters the first opening and exits the second opening, and vice versa. In one implementation, the first opening is at the top of the compartment and the second opening is at the bottom of the compartment. A control circuit may periodically cause the fan to change the direction of the chilled air flow. This effectively maintains a relatively uniform temperature throughout the compartment.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This patent application is a continuation-in-part, of copending U.S. patent application Ser. No. 11/891,692, filed Aug. 13, 2007. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates generally to food and beverage refrigeration and more particularly, to food and beverage refrigeration systems that alter airflow to maintain uniform temperatures. 
       BACKGROUND 
       [0003]    Maintaining a relatively uniform temperature is important in any refrigeration system, but it is particularly important in the context of food and beverage refrigeration. Without proper temperature distribution, some food in a refrigerator will be too cold, resulting in unwanted freezing and some will be too warm, which raises the risk of spoilage. In most contexts, a uniform temperature is not only desirable, but is mandated by regulations. 
         [0004]    Typically, pre-prepared airline food is stored in galley carts prior to serving to passengers. However, current galley cooling systems have to force air just above freezing either into the galley carts or into insulated compartments containing several galley carts just to ensure that the temperature does not exceed the required temperature in any portion of the carts. This is due to the temperature increase as the air passes through or over the galley carts to remove the heat entering the galley cart or compartment. The lower the maximum temperature required means that the cold air source is less efficient resulting in the need to use more powerful and heavier systems that use more electrical power. Thus, it can be seen that there is a need for a new method and apparatus for maintaining a uniform temperature in a refrigeration system. 
       SUMMARY 
       [0005]    In accordance with the foregoing, a method and apparatus for maintaining a uniform temperature in a refrigeration system is provided. According to an embodiment of the invention, the method involves directing chilled air through a galley cart or compartment in a first direction, switching the flow of the chilled air to a second direction (substantially opposite the first direction), and periodically repeating these steps. In another embodiment, the apparatus includes an air chiller, a storage enclosure defining a compartment, a duct system, and a valve system. The air chiller blows chilled air into the duct system. The compartment has a first and a second opening, each of which is coupled to the duct system. The valve system has valves that can be moved to route the chilled air so that it enters into the first opening and exits the second opening, or vice versa. In one embodiment, the first opening is at the top of the compartment and the second opening is at the bottom of the compartment, and the valve system is controlled by a control circuit that periodically switches the valves (via an actuator) to change the direction of the chilled air. This effectively maintains a relatively uniform temperature throughout the compartment. 
         [0006]    According to another embodiment of the invention, the method comprises blowing chilled air through the compartment in a first airflow direction, then reversing a rotational direction of fan rotation and blowing chilled air through the compartment in a second airflow direction that is substantially opposite the first airflow direction, and then reversing the rotational direction of fan rotation and blowing chilled air through the compartment in the first airflow direction. 
         [0007]    In another embodiment, an apparatus is provided for cooling food or beverages. The apparatus comprises an air chiller including first and second chiller ports and a fan having forward and reverse settings; a storage enclosure defining a compartment, the storage enclosure having a first opening and a second opening, which permits air to pass between the compartment and the outside of the enclosure; and a duct system coupled to the first and second chiller ports and to the first and second openings. The chilled air flows from the first chiller port into the duct system in a first airflow direction when the fan operates in the forward setting, and chilled air flows from the second chiller port into the duct system in a second airflow direction, that is substantially opposite the first airflow direction, when the fan operates in the reverse setting. 
         [0008]    In another embodiment a system is provided for cooling food or beverages. The galley cooling system comprises an enclosure; a cooling unit that generates chilled air, the cooling unit including a fan having forward and reverse settings; a duct system that transports the chilled air; and a plurality of carts disposed at least partially within the enclosure. Each cart of the plurality comprises a compartment, and has a first opening that connects the compartment to the duct system and a second opening that connects the compartment to the duct system. When the fan is in a forward setting, the chilled air is routed in a first airflow direction into the second opening of each of the plurality of carts and out of the first opening of each of the plurality of carts. When the fan is in a reverse setting, the chilled air is routed, in a second airflow direction that is substantially opposite to the first airflow direction, into the first opening of each of the plurality of carts and out of the second opening of each of the plurality of carts. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  shows a back perspective view of a galley cart that may be used in conjunction with an embodiment of the invention. 
           [0010]      FIG. 2  shows the cart depicted in  FIG. 1  with the door open. 
           [0011]      FIG. 3  is a front elevational view of a refrigeration system configured according to an embodiment of the invention, in which the valve system is in a first configuration. 
           [0012]      FIG. 4  is a view of the refrigeration system of  FIG. 3  in which the valve system is in a second configuration. 
           [0013]      FIG. 5  is a schematic of an embodiment of the refrigeration system in which the air is blown in the forward airflow direction through the galley cart. 
           [0014]      FIG. 6  is a schematic of the embodiment of the refrigeration system of  FIG. 5  in which the air is sucked in the reverse airflow direction through the galley cart. 
           [0015]      FIG. 7  is a schematic of an embodiment illustrating a change in the air temperature as it circulates through the refrigeration system of  FIG. 5 . 
           [0016]      FIG. 8  is a schematic of an embodiment illustrating a change in the air temperature as it circulates through the refrigeration system of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIGS. 1 and 2 , a galley cart that is used in conjunction with an embodiment is shown. The cart, generally labeled  10 , includes an enclosure  12  and castors  14  attached to the bottom of the enclosure  12 . The enclosure  12  has a front side  16  and a back side  19 . A door  20  is attached to the front side  16  by hinges  22 . The enclosure  12  has a storage compartment  24  defined by an inner surface  26  of the door  20 , a back wall  28 , a first side wall  30 , a second side wall  32 , a ceiling  34 , and a floor  36 . 
         [0018]    Protruding from the first and second side walls  30  and  32 , are rails  38 , which are configured to hold food trays. The enclosure  12  also has a divider  40  attached to the first and second side walls  30  and  32 . The divider  40  is disposed at or about the vertical midway point of the side walls  30  and  32 . The divider  40  has a pair of generally V-shaped cutouts  42 , one proximate to the door  20  and one proximate to the back wall  28 . The back wall  28  has a pair of generally square openings, a first opening  43  and a second opening  45 , in which a first grill  44  and a second grill  46  are disposed. The first and second openings  43  and  45  link the storage compartment  24  with the outside of the enclosure  12 , allowing air to move in or out through the grills  44  and  46 . 
         [0019]    The first grill  44  is located proximate to the ceiling  34  while the second grill  46  is located proximate to the floor  36 . The first and second grills  44  and  46  permit air to flow through the back wall  28 . 
         [0020]    Referring to  FIG. 3 , an example of a refrigeration system configured according to an embodiment of the invention will now be described. The system, generally labeled  100 , includes a cart corral  102 , an air chiller  104  disposed on top of the cart corral  102 , and a duct system  106  disposed within the cart corral  102 . The duct system has an inlet  108  and an outlet  110 . The air chiller  104  has an outlet that is coupled to the inlet  108  of the duct system  106 . The air chiller  104  also has an inlet that is coupled to the outlet  110  of the duct system  106 . 
         [0021]    The duct system  106  has a main duct  112  that extends around the inner periphery of the cart corral  102 . The main duct  112  starts at the inlet  108  of the duct system  106  and terminates at the outlet  110  of the duct system  106 . 
         [0022]    The cart corral  102  has an open side  114  that enables a cart to be parked within the corral  102 .  FIG. 3  shows 3 carts, each of the carts being parked within the corral  102 . Cart  10  in this example will be assumed to have the same configuration as the cart  10  of  FIG. 1 . Each cart  10  is parked so that its front side  16  faces the open side  114  of the cart corral  102 . 
         [0023]    In addition to the main duct  112 , the duct system  106  includes a first branch  116  and a second branch  118 . The first branch  116  has openings  120  that are next to or coupled with the first openings  43  of the carts  10 . Similarly, the second branch  118  has openings  122  that are next to or coupled with the second openings  45  of the carts  10 . 
         [0024]    Disposed within the duct system  106  is a valve system, which includes a first valve  124  and a second valve  126 . The refrigeration system  100  also includes a control unit  128 . The control unit  128  includes a control circuit  130 , which controls the movement of the first and second valves  124  and  126  by sending signals to an actuator that is mechanically coupled to the first and second valves  124  and  126 . The first valve  124  has at least two positions—a first position, shown in  FIG. 3 , in which the first valve  124  directs air flowing from the inlet  108  of the duct system  106  to flow to the first branch  116 , and a second position, shown in  FIG. 4 , in which the first valve  124  prevents air flowing from the inlet  108  of the duct system  106  directly to the first branch  116 . The second valve  126  also has at least two positions—a first position, shown in  FIG. 3 , in which the second valve  126  prevents air from flowing from the first branch  116  to the main duct  112 , and a second position, shown in  FIG. 4 , in which the second valve  126  permits air to flow from the first branch  116  to the main duct  112 . 
         [0025]    The refrigeration system  100  has at least two modes of operation—a normal airflow mode and a reversed airflow mode. The normal airflow mode will now be described with respect to  FIG. 3 . In the normal airflow mode, the valve system is in a configuration in which the first valve  124  and the second valve  126  are in their respective first positions. The air chiller  104  blows chilled air into the inlet  108  of the duct system  106 . Because the first valve  124  prevents airflow directly from the inlet  108  to the main duct  112 , the air flows from the inlet  108  to the first branch  116 , and then flows through openings  120  of the first branch  116  and through the first openings  43  of the carts  10 . The chilled air flows through the storage compartment  24  of each cart  10 , through the generally V-shaped cutouts  42 , and out the second openings  45  of the carts  10 . The chilled air exiting the second openings  45  passes through the second branch  118  and proceeds to the main duct  112  and out the outlet  110 . 
         [0026]    The reverse airflow mode will now be described with reference to  FIG. 4 . In the reverse airflow mode, the valve system is in a configuration in which the first valve  124  and the second valve  126  are in their respective second positions. The first valve  124  in its second position directs airflow from the inlet  108  to the main duct  112 . With the second valve  126  in its second position, airflow from the main duct  112  is prevented from flowing directly back to the chiller  104  through the outlet  110 . Instead, the air flows from the main duct  112  into the second branch  118 , through the openings  122  of the second branch  118 , and through the second openings  45  of the carts  10 . The chilled air then passes through the storage compartment  24  of each cart  10 , through the generally V-shaped cutouts  42 , and out the first openings  43  of the carts  10 . The chilled air exiting the first openings  43  passes through first branch  116  and proceeds to the main duct  112  and back to the chiller  104  through the outlet  110 . 
         [0027]    According to an embodiment of the invention, the refrigeration system periodically switches from the normal airflow mode to the reverse airflow mode. The time interval for switching the airflow can depend on many factors, such as the desired temperature of the system, and may also depend upon a sensed temperature of the system. This could include, for example, temperature sensors that determine whether there is a difference between the temperature at the top of a cart as compared to the temperature at the bottom of a cart. If such a difference exceeds a particular threshold, the airflow may be switched to provide more uniform cooling. In one implementation, the switching may occur periodically from 2 to 30 minutes. The switching between the normal mode and the reverse mode is controlled by the control circuit  130  of the control unit  128 . Periodically reversing the flow of air helps to equalize the temperature throughout the compartment  24 . 
         [0028]    As should be appreciate by one of skill in the art, the foregoing describes an embodiment where three different carts are accommodated within the cooling system of the present invention. The same invention may be readily implemented with respect to more or less carts. For example, the invention may be implemented with respect to just one cart, where two valves are operated to direct airflow through the cart initially in one direction, then to direct airflow through the cart in the other direction. 
         [0029]    In another embodiment of the invention, the air chiller includes a fan having both a forward and a reverse setting that allows the chiller to generate bi-directional airflow. This removes the need to rely on a valve set to create bi-directional airflow through the galley carts. Furthermore, it reduces the frequency with which the air chiller must be defrosted. 
         [0030]    In a system in which the chilled air generally exits the chiller through the same outlet, such chilled air exiting the outlet is much cooler than the air returning to the chiller through its inlet. In some embodiments, the temperature difference between the chiller outlet and inlet may be about 12-15° F. Over time, frost and ice build up in the chiller inlet and can block the flow of air back into the chiller. The chiller must then be shut down and defrosted. In a chiller having bi-directional flow of chilled air, the build-up of frost is slowed because it is spread over two ports instead of one outlet. As with the functioning of the valve set in  FIGS. 3-4 , bi-directional airflow from the chiller evens the temperature distribution in the galley carts. In the forward setting, the chiller fan functions in the blower mode. In the reverse setting, the chiller fan functions in the suction mode. The mode of the fan may be determined by a timer, a temperature sensor or other appropriate device. A chiller having such bi-directional airflow may be used in conjunction with refrigeration systems without valves that direct airflow and may also be used with refrigeration systems that include valves for directing airflow. When a chiller having such bi-directional airflow is used in an embodiment of a refrigeration system such as that illustrated in  FIG. 3 , the first and second valves may be maintained in either the first position or in the second position; it is not necessary to move the first and second valves from one position to another in order to have bi-directional airflow through the galley carts. 
         [0031]      FIG. 5  illustrates a side view of a refrigeration system configured according to an embodiment of the invention. In  FIG. 5  the refrigeration system, generally labeled  200 , comprises a galley cooling system  202  including an air chiller  204  and a duct system  206  disposed within the galley cooling system  202 . The duct system  206  has a first port  208  and a second port  210 . The air chiller  204  is comprised of an evaporator  203 , a fan motor  205 , and a fan  207 . The chiller  204  may be connected to a device  209  such as a temperature controller, and/or a timer or sensor. The device  209  in the preferred embodiment is an electronic device. The air chiller  204  has a first chiller port  228  that is coupled to the first port  208  of the duct system  206 . The air chiller  204  also has a second chiller port  230  that is coupled to the second port  210  of the duct system  206 . The duct system has a primary branch  216  and a secondary branch  218 . The primary branch starts at the first port  208  of the duct system  206  and extends to the second opening  45  of the cart  10 . The secondary branch extends between the first opening  43  of the cart  10  and the second port  210  of the duct system  206 . 
         [0032]    As depicted in  FIG. 5 , in the forward setting, the fan  207  blows chilled air through the first port  208  into the primary branch  216  of the duct system  206 . The air flows through the primary branch  216  into the lower portion of the storage compartment  24  of the cart  10  through the second opening  45  in the cart. The air flows from the bottom of the cart  10  to the top of the cart  10 . Thus, the chilled air passes through the storage compartment  24  of the cart  10 , through the generally V-shaped cutouts  42 , and out of the first opening  43  of the cart  10 . The chilled air exiting the first opening  43  passes through secondary branch  218  and back to the chiller  204  through the second port  210 . 
         [0033]      FIG. 6  illustrates a side view of the refrigeration system  200  of  FIG. 5  with the fan in the reverse setting functioning in the suction mode and the air flowing in the reverse direction as that in  FIG. 5 . In the suction mode, the fan  207  sucks air in from the primary branch  216  and blows chilled air into the secondary branch  218  of the duct system  206  through the second port  210 . The air flows from the secondary branch  218  into the upper portion of the storage compartment  24  of the cart  10  through the first opening  43 . The air flow in the galley cart  10  is from top to bottom. Thus, the chilled air passes through the storage compartment  24  of the cart  10 , through the generally V-shaped cutouts  42 , and out the second opening  45  of the cart  10 . The chilled air exiting the second opening  45  passes through the primary branch  216  and back to the chiller  204  through the first port  208 . In the embodiments shown in  FIGS. 5-6  only one cart is illustrated. However, in other embodiments, the galley cooling system may have a plurality of carts docked to it. 
         [0034]      FIG. 7  is a schematic illustrating the flow of air through the chiller in the preferred embodiment of  FIG. 5 . In this embodiment, air returning from the galley cart  10  ( FIG. 5 ) enters the air chiller ( 204 ) and is circulated through the evaporator  203  of the air chiller  204  ( FIG. 5 ). When the fan  207  is in the forward setting, the air entering the evaporator  203  is cooled by the evaporator such that chilled air flows from the evaporator  203  to the fan  207 . The air may be warmed slightly when passing through the fan motor  205  and may exit the fan  207  into the primary branch  216  and then the galley cart  10  at a slightly higher temperature. For example, in an embodiment when the fan  207  is in the forward setting, the air entering the evaporator  203  may be about 45° F. The temperature of the evaporator, in this example may be about 21.3° F. The evaporator  203  cools the air circulating through it so that the chilled air flowing from the evaporator  203  to the fan motor  205  is about 30° F. The air may be warmed slightly when passing through the fan motor  205  and may exit the fan  207  into the primary branch  216  and then the galley cart at a slightly higher temperature. For example, the air may exit the fan  207  at about 31° F. 
         [0035]      FIG. 8  illustrates a schematic of the flow of air through the chiller in the embodiment of  FIG. 6 . When the fan  207  is operating in suction mode ( FIG. 6 ), the return air enters the fan  207  from the primary branch  216  ( FIG. 6 ) of the duct system  206 . When the return air passes through the fan motor  205  and exits the fan motor  205  into the evaporator  203  it may be slightly warmed by the fan. However, as the air passes over the refrigerator coils of the evaporator  203 , its temperature drops and chilled air exits the evaporator  203 . For example, when the air enters the fan, it may be about 45° F. This return air passes through the fan motor  205  and exits the fan motor  205  into the evaporator  203  at about 46° F. In an embodiment, the temperature of the evaporator  203  may be about 22.3° F. Air passes over the refrigerator coils of the evaporator  203  resulting in a drop in temperature. In some embodiments there may be about a 15° F. drop in temperature and the air may exit the evaporator  203  at about 31° F. The higher evaporating temperature reduces the power consumption of the refrigeration system because the higher evaporating temperature decreases the compression ratio in the refrigeration system, when the condensing temperature is the same. The lower compression ratio reduces the power consumption of the refrigeration system. 
         [0036]    According to an embodiment of the invention, the refrigeration system periodically switches from the forward airflow to the reverse airflow. The time interval for switching the airflow can depend on many factors, such as the desired temperature of the system, and may also depend upon a sensed temperature of the system. This could include, for example, temperature sensors that determine whether there is a difference between the temperature at the top of a cart as compared to the temperature at the bottom of a cart. If such a difference exceeds a particular threshold, the airflow may be switched to provide more uniform cooling. In one implementation, the switching may occur periodically from 2 to 30 minutes. The switching between the forward mode and the reverse mode may be controlled by the control circuit  130  of the control unit  128 . In another embodiment, an air pressure differential sensor may be used to monitor the air pressure difference between the inlet and outlet of the evaporator. If the air pressure difference exceeds a particular threshold, the airflow may be reversed. 
         [0037]    It can be seen from the foregoing that a new and useful method and system for identifying and managing currency exposure has been described. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.