Abstract:
An aircraft is provided with an integrated galley refrigeration unit and vehicle cabin air conditioning packet. A control selectively determines whether the provision of cooled air into an air cooled galley takes precedent over the provision of cooled air into the passenger cabin. Valving is provided to selectively provide cold fluid to a recirculation air heat exchanger, which supplies supplemental cooled air for delivery into the passenger cabin. This refrigeration air heat exchanger is utilized when precedent is given to providing cooled air to the cabin. On the other hand, the valve is maintained in an off position when it is determined that the air cooled galleys should take precedent.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This application relates to a control and method for controlling a galley refrigeration unit for aircraft food galleys, and an air conditioning unit for supplying air to an aircraft cabin, where both of the units are controlled to provide the most efficient operation.  
         [0002]     Aircrafts are provided with a number of subsystems. In the aircraft passenger cabin, the temperature of the air is controlled by an air conditioning pack. This air conditioning pack supplies air to the cabin at a temperature as desired. The load on the air conditioning pack will vary with ambient temperature. As is known, when the aircraft is at altitude, the ambient temperature is often quite cold, and the air conditioning pack must be able to heat the air. At other times, the air conditioning pack must be able of cooling the air delivered to the cabin.  
         [0003]     In addition, aircrafts are provided with galleys to store food for the passengers. The food must be kept at refrigeration temperatures for a period of time. Thus, the galleys are typically provided with a refrigeration unit. The loads on the galley refrigeration unit, and the load on the air conditioning pack are not constant. Thus, both units are made larger than may be necessary.  
       SUMMARY OF THE INVENTION  
       [0004]     In the disclosed embodiment of this invention, a galley refrigeration unit is provided on the aircraft to provide cooled air to a food storage galley. An air conditioning pack is provided to supply cooled or heated air to a passenger cabin. A valve associated with the galley refrigeration unit selectively allows cold fluid to pass through a recirculation air heat exchanger. Air is driven over the recirculation air heat exchanger and cooled, and then sent to join with air from the air conditioning pack and delivered to the passenger cabin. The valve is open to direct the cold fluid to the recirculation air heat exchanger when the cooling load for the aircraft passenger cabin has a higher priority than providing additional cooling load to the food storage galley.  
         [0005]     At other times, cooling the food storage galley will take precedent over providing cooled air to the passenger cabin. In those cases, the valve will be closed.  
         [0006]     A control controls the use of the recirculation air heat exchanger to provide the additional cooled air following an appropriate algorithm.  
         [0007]     Since the two units are interrelated, such that the galley refrigeration unit can be utilized to provide cool air to the passenger cabin under certain conditions, the air conditioning pack can be made more compact, as it will be supplemented by the galley refrigeration unit.  
         [0008]     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawing that accompanies the detailed description can be briefly described as follows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a schematic view of a combined galley refrigeration unit and air conditioning pack for an aircraft.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]     An aircraft cooling system  20  is illustrated in  FIG. 1  having two major circuits. First, a cabin  22  is shown having temperature sensors  24  and  26 . A supply line  27  sends conditioned air to the cabin  22 . As shown, an air conditioning pack  28  either heats or cools the air such that the air is at a desired temperature when it reaches the cabin  22 . Feedback from the temperature sensors  24 / 26  is sent to a control, which can control the air conditioning pack to either increase or decrease the temperature, as necessary. The air passes from the air conditioning pack into a line  29  and downstream to the line  27  leading to the cabin.  
         [0011]     A galley refrigeration unit  30  serves to provide cooled air to galleys  32 , where food storage trays, etc., are stored. Heat sinks  34  allow heat to be pulled out of the galley refrigeration unit  30 . Refrigerant from the galley refrigeration unit  30  is cooled by heat sinks  34 , and is used to cool the cold liquid  20 . Heat exchangers  36  receive air from fans  38 , which then cools the air cooled galleys  32  after having passed over the heat exchangers  36 . Temperature sensors  40  and  42  supply air temperature information back to the control. This portion of the galley refrigeration  30  is generally as is known in the prior art. The motors for the fans may be variable speed, again as known in the prior art.  
         [0012]     While not shown in this figure, there is typically mirrored circuits of the air conditioning pack  28 , and a galley refrigeration unit  30  on an opposed side of the aircraft supplying conditioned air through a line  129  and to other galleys (not shown).  
         [0013]     In connection with this invention, bypass valves  44  and bypass lines  46  allow selective bypass of one or both of the heat exchangers  36 . In addition, a three-way valve  48  is positioned downstream of a flow line  47 , which is downstream of the heat exchangers  36 . Three-way valve  48  either connects the line  47  to a supplemental cabin conditioning line  50  or to a return line  52  which returns back to the galley refrigeration unit  30 . As shown, a fan  53  selectively drives air over a recirculation heat exchanger  51 , with the air passing through path  54  into a line  56 , where it joins the conditioned air from the line  29 .  
         [0014]     The control operates on the basis of an algorithm that determines whether additional cooled air should be supplied by the fan  53  passing over the recirculation heat exchanger  51 . If additional cooled air is to be supplied in this manner, the control moves the valve  48  to the position such that cold fluid passes from the line  47  into the line  50 . The fan  53  is running continuously. The air now passes over the recirculation air heat exchanger  51  and is cooled before passing into line  54 ,  56  and  27 . Dependent on the amount of cooling load to be supplied by the recirculation air heat exchanger, the valves  44  can also be actuated to bypass the heat exchangers  36 . Thus, at times when there is highest priority for cooling capacity at the cabin  22 , the heat exchangers  36  may be bypassed entirely, such that all available cooling capacity is supplied to the recirculation air heat exchanger  51 .  
         [0015]     An algorithm for operating this combined system  20  would generally take temperature information from each of the sensors, and in addition from a sensor providing an indication of ambient temperature.  
         [0016]     When the temperature sensors  24  or  26  on the cabin  22  indicate that the cabin temperature is too high or too low, the control controls the air condition pack to adjust this temperature. If the temperature in the cabin  22  is too high, the control may supply additional cooled air by operating the valve  48  and to supply cold fluid to the recirculation heat exchanger  51 .  
         [0017]     The air cooled galleys must be maintained at a temperature to preserve food. As an example, this temperature is generally approximately 30° F. Initially, when the refrigeration carts are being filled with food trays prior to flight departure, the galley refrigeration unit may be operating at a maximum cooling capacity. At this point, there is a high cooling load on the galley refrigeration unit to bring down the temperature of the air cooled galleys.  
         [0018]     Under certain conditions and as for example at this “initial loading” condition, the galley cooling may take priority over providing additional cooling to the passenger cabin. As an example, when the ambient ground temperature is high, it is important to maintain the air cooled galleys  32  at the desired temperature. In addition, there would be a high load on the air conditioning pack to bring down the temperature of the cabin  22 . Under these conditions, maintaining the temperature of the air cooled galleys will take precedent over bringing down the cabin temperature. It is considered permissible for the cabin temperature to be slightly higher than its target temperature under these conditions.  
         [0019]     Further, during cold conditions, the air conditioning pack  28  is only required to heat the air being delivered to the cabin  22 . No recirculation air heat exchanger cooling is desired. Therefore, the galley refrigeration unit need only focus on keeping the air cooled galleys  32  at the desired temperature.  
         [0020]     On the other hand, under hot ambient temperature conditions and especially when an aircraft has been sitting idle with all systems off, the aircraft cabin may be initially very hot. It would be desirable to bring the temperature down dramatically prior to loading passengers or food into the aircraft. Both systems may require some cooling at this time, but the higher priority will be given to the recirculating air heat exchanger cooling to initially reduce the cabin temperature.  
         [0021]     Once the cabin temperature is sufficiently reduced, the air cooled gallery requirements can then be met. Thus, under these conditions, initially the valves  44  may be opened along with the valve  48  directing cold fluid to the line  50 . In this manner, all cold fluid bypasses the heat exchangers  36  and all cooling capacity is passed through the recirculation heat exchanger  51 . This will ensure that the temperature of the cabin  22  is brought down as quickly as possible. Once the temperature in the cabin  22  reaches a certain range of the target temperature, the valves  44  may go into a position to pass cold fluid through the heat exchangers  36 . In this manner, the air cooled galleys will begin to move towards their target temperature, while cold fluid can continue to pass through the recirculation air heat exchanger. Once the food is loaded, providing cooling capacity to the air cooled galleys may take precedent over providing cold fluid to the recirculation air heat exchanger, and at that point the valve  48  may be turned to move cold fluid through the line  52 .  
         [0022]     Another instance where priority may be given to providing cooled air to the cabin may occur when systems have failed on the aircraft. As an example, if there is a loss of some power on the aircraft, there may be a limited amount of power available to power the galley refrigeration unit  30  and the air conditioning pack  28 . Under such circumstances, the algorithm may give precedent to supplying additional cooled air to the cabin.  
         [0023]     An algorithm can be developed by a worker of ordinary skill in the art to be programmed into the control to achieve the assignment of precedent and the control of the components along the lines outlined above. Of course, other ways of sharing the cooling load between the galley refrigeration unit and the air conditioning pack may come within the scope of this invention. As an example, the air conditioning pack may supplement the galley refrigeration unit.  
         [0024]     The invention has been disclosed in a preferred embodiment. However, one of ordinary skill in the art would recognize that certain modifications come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.