Abstract:
In order to provide a cooling station for at least one container to be cooled that has a housing surrounding a receiving space for receiving a product to be cooled, wherein the cooling station comprises at least one fan for generating a circulating air flow through the container, at least one cooler for cooling the circulating air flow and at least one docking place having at least one first docking point for removing the circulating air flow from the container to be cooled and having at least one second docking point for feeding the circulating air flow to the container to be cooled, that operates in a particularly energy-efficient manner, it is proposed that the cooling station comprises at least one closure element for closing a docking point of the cooling station in the absence of a container to be cooled.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation application of PCT/EP2007/007936 filed Sep. 12, 2007, the entire specification of which is incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present invention relates to a cooling station for at least one container that is to be cooled and has a housing surrounding a receiving space for receiving a product to be cooled, 
         [0000]    wherein the cooling station comprises
 
at least one fan for generating a circulating air flow through the container,
 
at least one cooler for cooling the circulating air flow and at least one docking place having at least one first docking point for removing the circulating air flow from the container to be cooled and having at least one second docking point for feeding the circulating air flow to the container to be cooled.
 
       BACKGROUND 
       [0003]    Such a cooling station is known from FR 2 442 035 A1. This cooling station comprises a circulating air channel, which connects the two docking points of the docking place to one another and is permanently open. 
         [0004]    The drawback of this is that warm ambient air may pass into the cooling station and warm the interior thereof. 
       SUMMARY OF THE INVENTION 
       [0005]    The underlying object of the present invention is to provide a cooling station of the initially described type that operates in a particularly energy-efficient manner. 
         [0006]    In a cooling station having the features of the preamble of claim  1  this object is achieved according to the invention in that the cooling station comprises at least one closure element for closing a docking point of the cooling station in the absence of a container to be cooled. 
         [0007]    By virtue of providing such a closure element the cold loss during a phase, in which the container to be cooled is not docked with the cooling station, is kept to a minimum, thereby increasing the energy efficiency of the cooling station according to the invention. 
         [0008]    Such a cooling station is particularly easy to operate if the closure element during undocking of a container to be cooled from the cooling station is movable automatically from an open position, in which the closure element frees the docking point, into a closed position, in which the closure element closes the docking point. 
         [0009]    For the sake of user friendliness it is further advantageous if the closure element during docking of a container to be cooled with the cooling station is movable automatically from a closed position, in which the closure element closes the docking point, into an open position, in which the closure element frees the docking point. 
         [0010]    The closure element for closing the docking point may for example take the form of a scovere. 
         [0011]    In a preferred development of the invention it is however provided that the closure element is mounted rotatably on the cooling station. 
         [0012]    It is further advantageous if the closure element is movable under the effect of gravity into a closed position, in which the closure element closes the docking point. 
         [0013]    If the receiving space of the container to be cooled is accessible via an access opening, preferably at the top of the container, for introducing a product to be cooled or for removing a cooled product from the receiving space, then the cooling station advantageously comprises a cover for closing this access opening while the container to be cooled is docked with the cooling station. 
         [0014]    Such a cover may in particular be mounted pivotably on the cooling station. 
         [0015]    In principle, the cooler of the cooling station may be of any desired design and the cooling effect of the cooler may be achieved in any desired manner. 
         [0016]    For example, it might be provided that the cooler takes the form of an evaporator of a refrigerating unit. 
         [0017]    The cooling station according to the invention is however of a particularly simple construction and is easy to manufacture and yet allows effective and energy-efficient cooling of the circulating air flow through the container to be cooled if the cooler takes the form of a heat exchanger that at the cold side contains a multiphase, flowable coolant. 
         [0018]    The multiphase coolant, which may in particular contain a socover ice phase that is suspended in a liquid phase, is flowable, in particular pumpable, and may therefore be fed from an external coolant source to the cooling station, so that there is no need for any refrigerating unit whatsoever inside the cooling station. 
         [0019]    A multiphase coolant may absorb heat from the circulating air flow and convert it to latent heat in that some of the socover phase of the coolant is melted without this leading to a variation of the temperature of the coolant, at any rate so long as the socover phase of the coolant is not completely melted. 
         [0020]    Such a latent coolant has a comparatively high specific energy density. 
         [0021]    The use of a multiphase coolant that has a defined melting temperature at the cold side of the cooler of the cooling station makes it possible to dispense with temperature control of the circulating air flow. 
         [0022]    In principle, however, a different coolant, for example a water-brine mixture or a conventional coolant, may alternatively be used in the cooler of the cooling station. 
         [0023]    In principle, the cold side of the heat exchanger might be designed as a coolant storage tank, in which the coolant, once introduced, remains until its heat absorption capacity is exhausted. 
         [0024]    In a preferred development of the invention it is however provided that a device allowing the coolant to circulate through the cooler is associated with the cooling station. The effect thereby achieved is that the cold side of the heat exchanger always has a particularly high heat absorption capacity. 
         [0025]    It is further preferably provided that the cooling station is connectable to an external coolant source, so that the multiphase flowable coolant may be drawn from the external coolant source and need not be produced or regenerated in the cooling station itself. 
         [0026]    In particular, it may be provided that there is associated with the cooling station a consumer circuit of the coolant, in which the coolant circulates through the cooler of the cooling station, wherein the consumer circuit is connected to a coolant supply system, from which fresh coolant may, when required, be fed to the consumer circuit. 
         [0027]    Such a coolant supply system may in particular comprise a process tank for storing a large quantity of coolant as well as a circulation line for feeding the stored coolant to at least one consumer circuit. 
         [0028]    It is further preferably provided that the multiphase, flowable coolant is a binary ice. 
         [0029]    Binary ice (also known as flow ice or smart ice) is a flowable and pumpable two-phase mixture of a socover ice phase and a liquid/alcohol phase (which therefore contains water and an alcohol as a substance lowering the freezing point), in which the ice phase is suspended. 
         [0030]    The melting temperature of the ice phase depends upon the type of alcohol used (for example ethanol) and upon the alcohol fraction selected. 
         [0031]    If this binary ice is used to cool the circulating air flow, then the binary ice absorbs heat from the circulating air flow and converts it to latent heat of the binary ice in that some of the ice phase of the binary ice is melted without this leading to a variation of the temperature of the binary ice, at any rate so long as the ice phase of the binary ice is not completely melted. 
         [0032]    Binary ice by virtue of these properties and by virtue of its pumpability is ideally suitable for use as a latent coolant in the cooling station according to the invention. 
         [0033]    By virtue of its ice fraction the binary ice moreover has a comparatively high specific energy density. 
         [0034]    In order to be able to cool a plurality of containers simultaneously by means of a circulating air flow, it is advantageous if the cooling station comprises a plurality of docking places for the simultaneous docking of a plurality of containers to be cooled. Such a cooling station having a plurality of docking places may be used in particular as a central cooling station for a portioning system of a large-scale catering establishment. 
         [0035]    Claim  13  is directed to a combination of a cooling station according to the invention and at least one container to be cooled, which is dockable with the cooling station and has a housing surrounding a receiving space for receiving a product to be cooled. 
         [0036]    A further underlying object of the present invention is to provide a container that has a housing surrounding a receiving space for receiving a product to be cooled, wherein the container is dockable with a cooling station and comprises at least one first docking point for removing circulating air from the container and at least one second docking point for feeding cooled circulating air to the container, the container having a particularly low heat loss after undocking from the cooling station. 
         [0037]    In a container having the features of the preamble of claim  14  this object is achieved according to the invention in that the container comprises at least one closure element for closing a docking point of the container when the container is undocked from the cooling station. 
         [0038]    By virtue of providing the closure element the cold losses from the receiving space of the container are reduced during a phase, in which the container is not docked with the cooling station. 
         [0039]    In this case, it is particularly user-friendly if the closure element during undocking of the container from the cooling station is movable automatically from an open position, in which the closure element frees the docking point of the container, into a closed position, in which the closure element closes the docking point of the container. 
         [0040]    For the sake of user friendliness it is further advantageous if the closure element during docking of the container with the cooling station is movable automatically from a closed position, in which the closure element closes the docking point of the container, into an open position, in which the closure element frees the docking point of the container. 
         [0041]    The closure element closing the docking point may for example take the form of a scovere. 
         [0042]    In a preferred development of the invention it is however provided that the closure element is mounted rotatably on the container. 
         [0043]    The container is operationally particularly reliable if the closure element is movable under the effect of gravity into a closed position, in which the closure element closes the docking point of the container. Thus no external drive power is needed to move the closure element into the closed position. 
         [0044]    If the container has an access opening to the receiving space for the product to be cooled, through which a product to be cooled is introducible into the receiving space or a cooled product is removable from the receiving space, then the container is preferably provided with a cover for closing this access opening while the container is docked with the cooling station in order to convey the cooled circulating air flow with minimum loss through the receiving space of the container. 
         [0045]    Such an access opening is preferably disposed at the top of the container. 
         [0046]    If the cover is formed to be at least partially transparent, this offers the advantage that by glancing through the cover it is easy to determine which product to be cooled is contained in the relevant container, thereby making it easy to select the correct container that is to be moved for example up to a food conveyor belt, particularly and precisely when a plurality of containers to be cooled are docked with the cooling station. 
         [0047]    The container to be cooled preferably takes the form of a dispenser having a vertically movable platform that carries the product to be cooled. 
         [0048]    Such a platform may in particular be guided displaceably on at least one guide rod. 
         [0049]    The product to be cooled that is accommodated in the receiving space of the container preferably comprises food and/or drinks and/or tableware. 
         [0050]    Claim  24  is directed to a combination of at least one cooling station for at least one container to be cooled that is dockable with the cooling station, wherein the cooling station comprises at least one fan for generating a circulating air flow through the container, at least one cooler for cooling the circulating air flow and at least one docking place having at least one first docking point for removing the circulating air flow from the container to be cooled and having at least one second docking point for feeding the circulating air flow to the container to be cooled, and at least one container according to the invention. 
         [0051]    Claim  25  is directed to a combination of at least one cooling station according to the invention and at least one container according to the invention. 
         [0052]    The cooling station according to the invention, the container according to the invention and the combinations according to the invention of a cooling station according to the invention and a container to be cooled, a cooling station and a container according to the invention to be cooled or a cooling station according to the invention and a container according to the invention to be cooled are particularly suitable for use as components of a portioning system for a large-scale catering establishment. 
         [0053]    Besides the cooling station and the container dockable with the cooling station, such a portioning system may in addition comprise further components, in particular a food conveyor belt, at least one rack trolley and at least one cooling station adapted to the rack trolley and having a receiving space for completely receiving the rack trolley. 
         [0054]    The concept according to the invention offers the advantage that the container to be cooled may be moved up to a desired location without any cooling device whatsoever having to be moved along with the container. 
         [0055]    The container to be cooled may therefore be of a small, light and manoeuvrable design combined with a relatively high capacity. 
         [0056]    Because there is no need for a refrigerating unit in the cooling station according to the invention, the cooling station according to the invention does not generate waste heat. The area surrounding the cooling station is therefore not loaded with waste heat that has to be dissipated. 
         [0057]    The cold from the multiphase, flowable coolant is supplied by the circulating-air cooling system precisely to the product to be cooled in the receiving space of the container to be cooled, with the result that large areas of a portioning centre, in which such a cooling station is disposed, may remain uncooled. This saves energy and prevents the operating personnel of the portioning centre from being exposed to the cold. 
         [0058]    Given correct layout of the cooler and an adequate ratio of cooler capacity to cooling demand in the event of use of binary ice and a binary ice temperature of ca. −3° C., the temperature arising in the receiving space of the container to be cooled is always in the region of between 0° C. and 10° C. 
         [0059]    Because of the high energy density of the binary ice compared to conventional liquid coolants, when binary ice is used only a considerably lower volumetric flow need be circulated through the cooler, this having a positive effect on the energy balance of the system. 
         [0060]    By means of the cooling station according to the invention the temperature of the product to be cooled in the receiving space of the container to be cooled may be both maintained (for example in the case of covered and already portioned cold food) as well as lowered (for example in the case of tableware after a dishwashing process). 
         [0061]    Where necessary, the containers cooled by means of the cooling station are undocked from the cooling station and brought to their place of use, for example pushed up to a food conveyor belt, where trays are loaded with the cooled product from the receiving space of the cooled container. 
         [0062]    It is particularly advantageous if the circulating-air cooling of the container to be cooled is not started until it is required, namely when the container is docked with the cooling station. 
         [0063]    The circulating air flows directly against the product to be cooled in the receiving space of the container to be cooled, with the result that the product to be cooled is cooled in a very efficient manner and so short cooling cycles may be realized. 
         [0064]    The containers to be cooled may be of a small and maneuverable design because they themselves do not contain any cooling equipment. 
         [0065]    The containers to be cooled may function as a cold store substitute. 
         [0066]    When there is no cooling demand because no container to be cooled is docked with a docking place of the cooling station, the circulating-air cooling of the relevant docking place is turned off by means of a switch. 
         [0067]    The use of binary ice as a multiphase, flowable coolant offers the advantage that this coolant absorbs heat from the circulating air as latent heat and so in the cooler of the cooling station at the cold side there is always an optimum temperature for cooling food of ca. −3° C. without any temperature control being required for this purpose, thereby allowing a very simple construction of the cooling station according to the invention. 
         [0068]    It is only if a container docked with the cooling station is to be permanently cooled that a cyclical defrosting operation has to be activated. 
         [0069]    The quantity of heat that may be absorbed by binary ice without impairing the cooling action of the binary ice is markedly higher than in the case of coolants without a phase change. The volumetric flow of the coolant through the cooler of the cooling station that is needed to cool the circulating air is therefore markedly lower when binary ice is used. 
         [0070]    The cooling station according to the invention and the container according to the invention are particularly suitable for use in the portioning of food in institutional catering, in particular in centralized kitchens, large hospitals etc. 
         [0071]    Further features and advantages of the invention are the subject matter of the following description and the graphical representation of embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0072]      FIG. 1  a diagrammatic top view of a portioning system for a large-scale catering establishment having a central cooling station and a food conveyor belt, along which a tray-stacking trolley, a serving trolley, a plurality of tableware- and food dispensers, a low mobile cooling station with an inserted low rack trolley, a high mobile cooling station with an inserted high rack trolley and a tray-conveying trolley are disposed; 
           [0073]      FIG. 2  a diagrammatic representation of a binary ice supply system for the central cooling station, for a high mobile cooling station and for a low mobile cooling station; 
           [0074]      FIG. 3  a diagrammatic top view of a central cooling station having six docking places for movable dispensers; 
           [0075]      FIG. 4  a diagrammatic vertical section through a docking place of a central cooling station; 
           [0076]      FIG. 5  a diagrammatic vertical longitudinal section through a mobile dispenser with a cover placed thereon; 
           [0077]      FIG. 6  a diagrammatic vertical section through a docking place of a central cooling station with a mobile dispenser docked therewith; 
           [0078]      FIG. 7  an enlarged representation of the region I of  FIG. 6 ; 
           [0079]      FIG. 8  a diagrammatic longitudinal section through a second form of construction of a mobile dispenser, the docking points of which are provided with closure flaps, the closure flaps being situated in a closed position; 
           [0080]      FIG. 9  an enlarged representation of the region II of  FIG. 8 , wherein the represented closure flap is situated in an open position; 
           [0081]      FIG. 10  a diagrammatic section through a third form of construction of a mobile dispenser, onto which a cover made of Plexiglas has been placed; 
           [0082]      FIG. 11  a diagrammatic vertical section through a docking place of a central cooling station and a mobile dispenser, which is docked therewith and onto which no cover has been placed, wherein a cover is mounted pivotably on the central cooling station and situated in an open position, in which a top access opening of the mobile dispenser is open; 
           [0083]      FIG. 12  a diagrammatic vertical section corresponding to  FIG. 11  through a docking place of a central cooling station and a mobile dispenser docked therewith, wherein the cover mounted pivotably on the central cooling station has been pivoted into a closed position, in which the cover closes a top access opening of the mobile dispenser; 
           [0084]      FIG. 13  a diagrammatic perspective representation of a high mobile cooling station, into which a high rack trolley is insertable; 
           [0085]      FIG. 14  a diagrammatic front view of the high mobile cooling station of  FIG. 13 , wherein part of the back wall of the cooling station has been removed to reveal the cooling coils of a cooler of the cooling station; 
           [0086]      FIG. 15  a diagrammatic perspective representation of a high rack trolley; 
           [0087]      FIG. 16  a diagrammatic perspective representation of a combination of a high mobile cooling station and a high rack trolley inserted into the cooling station; 
           [0088]      FIG. 17  a diagrammatic front view of the combination of the high mobile cooling station and the high rack trolley inserted into the cooling station; 
           [0089]      FIG. 18  a diagrammatic, part-sectional bottom plan view of the combination of the high mobile cooling station and the high rack trolley inserted into the cooling station, in which a circulating air flow passing through the cooling station and the rack trolley is diagrammatically represented by arrows; 
           [0090]      FIG. 19  a diagrammatic perspective representation of a low mobile cooling station; 
           [0091]      FIG. 20  a diagrammatic perspective representation of a low rack trolley; and 
           [0092]      FIG. 21  a diagrammatic perspective representation of the low mobile cooling station of  FIG. 19 , in which the circulating air flow passing through the low rack trolley in the inserted state thereof is additionally represented by arrows. 
       
    
    
       [0093]    In all of the figures identical or functionally equivalent elements are denoted by the same reference characters. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0094]    A portioning system  100  for portioning food and/or drinks in a large-scale catering establishment is represented as a whole in  FIG. 1  and comprises a food conveyor belt  102 , which is cooled by circulating air and the running direction of which is indicated by arrows  104 . 
         [0095]    In an initial region  106  (at the bottom in the representation of  FIG. 1 ) trays that are removed from a tray-stacking trolley  110  by an operator standing at the point  108  are placed onto the food conveyor belt  102  and loaded with uncooled food, drinks or tableware from a serving trolley  112 . 
         [0096]    From a mobile dispenser  116 , which is positioned next to the food conveyor belt  102  and the top access opening  118  of which is freely accessible, cooled food, drinks and/or tableware are placed by an operator standing at the point  114  onto the trays conveyed by the food conveyor belt  102  in the running direction  104 . 
         [0097]    Portions of food from Gastronorm containers suspended from a low rack trolley  122  are placed by an operator standing at the point  120  onto the trays conveyed further in the running direction  104  of the food conveyor belt  102 . 
         [0098]    The low rack trolley  122  is inserted into a low mobile cooling station  124  that generates a cooled circulating air flow through the low rack trolley  122 . 
         [0099]    From a second mobile dispenser  116 ′, the top access opening  118  of which is freely accessible, further food, drinks and/or tableware items are placed by an operator standing at the point  126  onto the trays conveyed further in the running direction  104  of the food conveyor belt  102 . 
         [0100]    From Gastronorm containers that are suspended from a high rack trolley  130  portions of cooled food are placed by an operator standing at the point  128  onto the trays conveyed further in the running direction of the food conveyor belt  102 . 
         [0101]    The high rack trolley  130  is inserted into a high mobile cooling station  132  that generates a cool circulating air flow through the high rack trolley  130 . 
         [0102]    In an end region  134  of the food conveyor belt  102  the fully loaded trays are removed from the food conveyor belt  102  and introduced into the receiving chamber of a tray-conveying trolley  138 , which is pre-cooled by means of binary ice, by an operator situated at the point  136 . 
         [0103]    Disposed at a distance from the food conveyor belt  102  is a central cooling station  140  that comprises a plurality of—for example five—docking places  142  for the docking of mobile dispensers  116 , wherein the central cooling station  140  generates a cool circulating air flow through each of the docked mobile dispensers  116 . 
         [0104]    The cold needed for cooling items or keeping items cool is supplied to all of the cooling elements of the portioning system  100  by means of a multiphase, flowable coolant, in particular in the form of a binary ice. 
         [0105]    The binary ice supply system  144  of the portioning system  100  is diagrammatically represented in  FIG. 2  and comprises a process tank  146 , which is used as the main reservoir for the binary ice and in which the binary ice is continuously circulated by means of motor-driven rotors  148  in order to obtain as homogeneous a binary ice mixture as possible in the process tank  146 . 
         [0106]    In a primary circuit  150  binary ice from the process tank  146  is fed by means of a primary pump  152  to an ice generator  154  having a motor-driven mixer  156 , which simultaneously scrapes off ice that has frozen on the inner wall of the ice generator  154 , and from there back into the process tank  146 . 
         [0107]    The ice generator  154  is cooled by means of a conventional refrigeration device  158 , which comprises a refrigerant circuit  160  having a refrigerant compressor  162 , a condenser  164  and a flash restrictor  166 . 
         [0108]    The binary ice, which is generated in the ice generator  154  by means of the cold supplied by the refrigeration device  158  and is stored in the process tank  146 , is circulated in a secondary circuit  168  and discharged from there to local consumer circuits  174  of the low mobile cooling station  124 , the high mobile cooling station  132  and the central cooling station  140 . Melted binary ice from these local consumer circuits  174  is received by the secondary circuit  168  and fed into the process tank  146 . 
         [0109]    The secondary circuit  168  comprises a circulation line  170  that leads from the process tank  146 , past the standing positions of the low mobile cooling station  124  and the high mobile cooling station  132  along the food conveyor belt  102  and, from there, to the central cooling station  140  and back into the process tank  146 . Disposed in the circulation line  170  is a secondary pump  172  that circulates the binary ice from the process tank  146  through the circulation line  170 . 
         [0110]    Each of the consumer circuits  174  is connected to the circulation line  170  by a branch line  176 , which branches off from the circulation line  170  and is connected to a first input  178  of a three-way valve  180 . 
         [0111]    In each case, a binary-ice inlet line  184  leads from an output  182  of the three-way valve  180  to a binary-ice inlet connection of the respective cold consumer, for example the low mobile cooling station  124 . 
         [0112]    Inside the respective consumer a line system is provided, which carries the binary ice from the binary-ice inlet connection through a cold consumer, in particular a cooler, and back to a binary-ice return connection of the respective consumer. 
         [0113]    The binary-ice return connection is connected to a binary-ice return line  186  that leads to a junction  188 . 
         [0114]    From the junction  188  a binary-ice return line  190  leads to a second input of the three-way valve  180 , thereby producing a closed consumer circuit  174 . 
         [0115]    A binary-ice discharge line  192  further leads from the junction  188  back to the circulation line  170  of the secondary circuit  168 . 
         [0116]    In order to supply fresh binary ice from the secondary circuit  168  to the respective consumer circuit  174 , the respective three-way valve  180  is switched into a state, in which the first input of the three-way valve  180  is connected to the output thereof, so that fresh binary ice passes through the branch line  176  into the binary-ice inlet line  184 . 
         [0117]    Disposed in the binary-ice inlet line  184  is a pump  194  that feeds the binary ice from the binary-ice inlet line  184  into the respective consumer, for example into the low mobile cooling station  124 . 
         [0118]    As in this filling state of the consumer circuit  174  the second input of the three-way valve  180 , to which the binary-ice return line  190  is connected, is closed, simultaneously with the supply of fresh binary ice through the branch line  176  spent melted binary ice is fed through the binary-ice discharge line  192  into the circulation line  170  of the secondary circuit  168  and, from there, back into the process tank  146 . 
         [0119]    Once the desired quantity of fresh binary ice has been fed to the consumer circuit  174 , the three-way valve  180  is switched into a state, in which its second input is connected to the output and the first input  178  of the three-way valve  180  is closed. 
         [0120]    In this state, the binary ice is circulated by means of the pump  194  in the closed consumer circuit  174  through the respective consumer, for example the low mobile cooling station  124 . 
         [0121]    The switching of the three-way valve  180  between its two states may be triggered for example because of the signal of a temperature sensor that measures a temperature inside the cold consumer or the temperature of the binary ice at one point of the consumer circuit  174 . 
         [0122]    Since the junction  188  of the consumer circuit  174  is situated lower than the circulation line  170  of the secondary circuit  168 , as a result of the effect of gravity substantially no binary ice passes from the consumer circuit  174  into the circulation line  170  of the secondary circuit  168  so long as the consumer circuit  174  is closed by the three-way valve  180  and binary ice may pass from the junction  188  through the binary-ice return line  190  back into the binary-ice inlet line  184 . 
         [0123]    The consumer circuits  174  of the low mobile cooling station  124 , the high mobile cooling station  132  and the central cooling station  140  are all of a substantially identical construction and operate in the previously described manner. 
         [0124]    The binary-ice inlet lines  184  leading to the mobile cooling stations  124  and  132  and the binary-ice return lines  186  are preferably of a flexible design to allow the mobile cooling stations  124  and  132  to be disposed in different positions relative to the circulation line  170  of the secondary circuit  168 . 
         [0125]    Besides the previously described cold consumers, further consumers  196 , for example the food conveyor belt  102 , another cooled portioning- or conveyor belt, one or more cold stores, one or more refrigerators etc., may additionally also be supplied by means of a consumer circuit  174  with circulating binary ice and connected by a respective branch line  176  and a binary-ice discharge line  192  to the circulation line  170  of the secondary circuit  168 . 
         [0126]    There now follows a detailed description of the construction of the central cooling station  140  with reference to  FIGS. 3 to 7 . 
         [0127]    The central cooling station  140  comprises a plurality of docking places  142  for the docking of in each case one mobile dispenser  116  of the type represented in  FIGS. 5 and 6 . 
         [0128]    In this case, as is represented for example in  FIGS. 1 and 2 , a plurality of—for example five—docking places  142  may be arranged linearly alongside one another. 
         [0129]    In  FIGS. 1 and 2  in each case three of the docking places  142  are occupied by docked dispensers  116 , while two further docking places  142  are vacant. 
         [0130]    It is also possible to position two docking places  142  in each case back to back so that they may each be approached by a dispenser  116  from mutually opposite directions, as is represented in  FIG. 3  by way of example for a total of six docking places  142 , two of which are positioned in a pair back to back in each case. 
         [0131]    As may best be seen from  FIG. 4 , each docking place  142  of the central cooling station  140  comprises a supporting frame  198  having supports  200 , by which the central cooling station  140  is supported on a floor, and having cross-members  202  extending substantially horizontally and transversely of a longitudinal direction  230  of the central cooling station  140  and serving as guide devices for a dispenser  116  that is to be moved up to the docking place  142 . 
         [0132]    Two longitudinal members  204  extending substantially horizontally and at right angles to the cross-members  202  carry a substantially cuboidal housing  206 , which comprises a bottom wall  208 , a vertical back wall  210 , a vertical front wall  212 , non-illustrated vertical side walls and a vertical top wall  214 . 
         [0133]    Each wall of the housing  206  is provided with an inner lining  216  and an outer lining  218  made of sheet metal as well as with thermal insulation  220  disposed between the inner lining  216  and the outer lining  218 . 
         [0134]    The front wall  212  facing the respective docked dispenser  116  has a first docking point  222  in the form of an air inlet  224  and, beneath this, a second docking point  226  in the form of an air outlet  228 . 
         [0135]    Each of the two docking points  222 ,  226  comprises a substantially rectangular air through-opening, which extends in the longitudinal direction  230  of the central cooling station  140  and is closable by means of a closure flap  232  when there is no dispenser  116  at all docked with the relevant docking place  142 . 
         [0136]    Each of the closure flaps  232  is mounted on the housing  206  rotatably about an axis of rotation, which extends horizontally and parallel to the longitudinal direction  230  of the central cooling station  140 , in such a way that the closure flap  232  is rotatable from the closed position represented in  FIG. 4 , in which the closure flap  232  closes the through-opening of the respective docking point  222  and/or  226 , inwards into the open position represented in  FIG. 7 , in which the closure flap  232  frees the through-opening of the respective docking point  222  and/or  226 . 
         [0137]    So that the closure flap  232  during docking of the dispenser  116  is rotated automatically from the closed position into the open position, each closure flap  232  is provided with in each case two actuating projections  234 , which are mutually spaced apart in the longitudinal direction of the closure flap  232  and which in the closed state of the closure flap  232  project slightly out beyond the opening cross section of the air through-opening and are displaced by the dispenser  116  into the interior of the housing  206  when the dispenser  116  is moved against the front wall  212  of the docking place  142  (see  FIGS. 6 and 7 ). 
         [0138]    By virtue of this displacement of the actuating projections  234  the respective closure flap  232  is rotated about its axis of rotation from the closed position into the open position. 
         [0139]    When the mobile dispenser  116  is removed from the docking place  142 , each closure flap  232  rotates under the effect of gravity from the open position back into the closed position, in which the closure flap  232  closes the through-opening of the respective associated docking point  222  and/or  226 . 
         [0140]    As may best be seen from  FIG. 4 , in the interior of the housing  206  of each docking place  142  an air baffle  236 , a fan  238  and a cooler  240  are disposed between the upper first docking point  222  and the lower second docking point  226 . 
         [0141]    The cooler  240  takes the form of a heat exchanger and contains heat exchanger coils, which at the cold side are filled with binary ice that is circulated through the central cooling station  140  in the consumer circuit  174  associated with the central cooling station  140 . 
         [0142]    In this case, the coolers  240  of the various docking places  142  may be connected in series or in parallel to one another. 
         [0143]    In order that water condensate formed at the cooler  240  may be removed from the housing  206  of the docking place  142  and collected, there is disposed at the bottom of the housing  206  a collecting trough  242 , the base of which is inclined towards a mouth orifice of a collecting pipe  244 , wherein the collecting pipe  244  extends through the bottom wall  208  of the housing  206  into a condensate collecting tank, which is suspended from the supporting frame  198  and may for example take the form of a Gastronorm food container. 
         [0144]    The dispenser  116  dockable with the docking place  142  of the central cooling station  140  is individually represented in  FIG. 5  and takes the form of a mobile container  247  comprising a substantially cuboidal, thermally insulated housing  248  that is provided at its underside with castors  250 , by means of which the dispenser  116  is movable over a floor. 
         [0145]    The receiving space  252  surrounded by the housing  248  and provided for receiving a product to be cooled is accessible via an access opening  118  at the top of the dispenser  116  in order to introduce product to be cooled into the receiving space or remove cooled product from the receiving space  252 . 
         [0146]    This top access opening  118  is closable by means of a thermally insulated cover  254  that may be placed onto the housing  248 . 
         [0147]    Disposed in the receiving space  252  is a platform  256  that carries the product to be cooled and is guided in a vertically displaceable manner on a plurality of vertical guide rods  258 . 
         [0148]    A front wall  260  of the housing  248  of the dispenser  116  that faces the docking place  142  of the central cooling station  140  in the docked state of the dispenser  116  is provided with a first docking point  262  in the form of an air outlet  264  and, beneath this, with a second docking point  266  in the form of an air inlet  268 . 
         [0149]    Each of the docking points  262 ,  266  of the dispenser  116  comprises an air through-channel, by which the receiving space  252  is connected to the exterior of the housing  248  of the dispenser  116 . 
         [0150]    In the form of construction represented in  FIG. 5  these air through-channels are permanently open. 
         [0151]    The dispenser  116  is loaded with tableware, cold food or cold drinks and then docked with a vacant docking place  142  of the central cooling station  140  by being moved, front wall  260  of its housing  248  first, against the front wall  212  of the housing  206  of the docking place  142 . 
         [0152]    To push and steer the mobile dispenser  116  a push handle  270  is used, which is disposed on a back wall  272  of the housing  248  of the dispenser  116  remote from the front wall  260 . 
         [0153]    When the dispenser  116  is moved into the docking place  142 , the first docking point  262  of the dispenser  116  comes into contact with the first docking point  222  of the docking place  142  and the second docking point  266  of the dispenser comes into contact with the second docking point  226  of the docking place  142 , thereby producing air ducts, which are sealed off from the environment and by which the interior of the housing  206  of the docking place  142  is connected to the receiving space  252  of the mobile dispenser  116 . 
         [0154]    During docking the actuating projections  234  on the closure flaps  232  of the docking points  222  and  226  of the docking place  142  are displaced by the docking points  262  and  266  respectively of the dispenser  116 , so that the closure flaps  232  are moved from their closed position into their open position and the air ducts between the dispenser  116  and the docking place  142  are open. 
         [0155]    Once the dispenser  116  is docked with the docking place  142 , a circulating air flow is generated by means of the fan  238  and passes from the fan  238  through the cooler  240  and through the second docking points  226  and  266  into a region between a bottom wall  274  of the housing  248  of the dispenser  116  and a bottom sheet  276  disposed above it and, from there, into the back wall  272  of the dispenser  116 . 
         [0156]    Through air through-openings  278 , which are distributed over the entire height of the back wall  272 , the circulating air passes over the entire height of the receiving space  252  into the receiving space  252  in order to cool the product to be cooled that is situated there. 
         [0157]    Through air through-openings  280 , which are distributed over the entire height of the front wall  260  of the housing  248  of the dispenser, the circulating air passes out of the receiving space  252  into the front wall  260  of the dispenser  116  and, from there, through the first docking point  262  of the dispenser  116  and the first docking point  222  of the docking place  142  back to the fan  238 , with the result that the circuit is closed. 
         [0158]    The circulating air flow is represented diagrammatically by the arrows  282  in  FIG. 6 . 
         [0159]    The cooling of the circulating air in this case is effected by heat transfer in the cooler  240  in the form of a heat exchanger to the binary ice flowing through the cooler  240  at the cold side. 
         [0160]    By virtue of the use of binary ice as a coolant no temperature regulation of the circulating air cooling system is necessary. The binary ice circulates permanently through the cooler  240  of the docking place  142 . 
         [0161]    The dispenser  116  remains docked with the docking place  142  of the central cooling station  140  and continues to be cooled by circulating air until it is pushed up to the food conveyor belt  102  for removal of the cooled product it contains. 
         [0162]    By virtue of the fact that the access opening  118  of the dispenser  116  in the docked state is covered by the thermally insulated cover  254 , an energy-saving cooling operation is guaranteed. 
         [0163]    At the food conveyor belt  102  as a rule no further cooling of the dispenser  116  is necessary because the cooled product, in particular the cooled tableware, as a result of its high specific heat capacity has stored enough cold to remain sufficiently cold, i.e. at a temperature of less than 8° C., during the relatively short period of the portioning at the food conveyor belt  102 . 
         [0164]    For the portioning at the food conveyor belt  102  the cover  254  is removed in order to gain access through the access opening  118  to the cooled product in the receiving space  252 . 
         [0165]    A second form of construction of a mobile dispenser  116  that is represented in  FIGS. 8 and 9  differs from the previously described form of construction represented in  FIGS. 5 and 6  in that the air through-channels of the first docking point  262  and the second docking point  266  are not permanently open but are closed in the undocked state in each case by means of a closure flap  284 . 
         [0166]    Each of the closure flaps is mounted on the housing  248  rotatably about an axis of rotation, which extends horizontally and parallel to the front wall  260  of the housing  248  of the dispenser  116 , in such a way that the closure flap  284  is rotatable out of the closed position represented in  FIG. 8 , in which the closure flap  284  closes the air through-channel of the respective associated docking point  262  and/or  266 , into the open position represented in  FIG. 9 , in which the closure flap  284  frees the relevant air through-channel. 
         [0167]    To achieve the effect whereby the closure flaps  284  during docking of the dispenser  116  with the central cooling station  140  each rotate automatically out of the closed position into the open position, each of the closure flaps  284  is provided with one or more actuating projections  286 , which at least in the closed state project slightly out beyond the opening cross-section of the respective associated air through-channel and during docking of the dispenser  116  with the central cooling station  140  are displaced by the respective associated docking point  222  and/or  226  of the docking place  142  of the central cooling station  140  into the interior of the dispenser  116 , with the result that the respective closure flap  284  is automatically rotated out of the closed position into the open position. 
         [0168]    During undocking of the dispenser  116  from the docking place  142 , the closure flaps  284  rotate under the effect of gravity out of the open position back into the closed position, so that the air through-channels of the docking points  262 ,  266  of the dispenser  116  are closed when the dispenser  116  is undocked from the central cooling station  140 . 
         [0169]    Otherwise the second form of construction of a dispenser  116  represented in  FIGS. 8 and 9  is identical in construction and function to the first form of construction represented in  FIGS. 5 and 6 , to the previous description of which reference is made in this respect. 
         [0170]    This second form of construction of a dispenser  116  with closure flaps  284  may be used together with a central cooling station  140  that likewise has closure flaps  232  at its docking points  222 ,  262  or with an alternative central cooling station  140  having air inlets  224  and air outlets  228  that are permanently open. 
         [0171]    A third form of construction of a mobile dispenser  116  that is represented in  FIG. 10  differs from the two previously described forms of construction in that, instead of a non-transparent cover  254  made of a sheet-metal lining and thermal insulation disposed in the interior of the lining, a cover  254 ′ made of a transparent material, for example of Plexiglas, is placed onto the housing  248  of the dispenser  116  in order to close the top access opening  118  of the dispenser  116  when the latter is docked with the central cooling station  140 . 
         [0172]    The use of a transparent cover  254 ′ offers the advantage that by glancing through the cover  254 ′ it is easy to determine which product to be cooled is contained in the relevant dispenser  116 , thereby making it simple to select the correct dispenser  116  that is to be moved up to the food conveyor belt  102 , particularly if a plurality of mobile dispensers  116  are docked with the central cooling station  140 . 
         [0173]    Otherwise the form of construction of a mobile dispenser  116  represented in  FIG. 10  is identical in construction and function to the first form of construction represented in  FIGS. 5 and 6 , to the previous description of which reference is made in this respect. 
         [0174]    A second form of construction of a central cooling station  140  that is represented in  FIGS. 11 and 12  differs from the first form of construction represented in  FIGS. 3 ,  4 ,  6  and  7  in that it additionally comprises a thermally insulated cover  288  that is mounted on top of the housing  206  of a docking place  142  so as to be pivotable about a pivot axis  290  oriented horizontally and parallel to the longitudinal direction  230  of the central cooling station  140 . 
         [0175]    This cover  288  is used to close the top access opening  118  of a dispenser  116  docked with the central cooling station  140  if the relevant dispenser  116  does not have its own cover  254 . 
         [0176]    Prior to the docking of such a dispenser  116 , the cover  288  is situated in the open position represented in  FIG. 11 , in which the cover  288  frees the access to the docking place  142  for a dispenser  116  that is to be inserted. 
         [0177]    After docking of the dispenser  116 , the cover  288  is pivoted out of its open position into the closed position represented in  FIG. 12 , in which the cover  288  rests on the housing  248  of the dispenser  116  and closes the top access opening  118  of the dispenser  116 , thereby preventing the circulating air that is conveyed through the receiving space  252  of the dispenser  116  from escaping into the environment. 
         [0178]    Otherwise the second form of construction of a central cooling station  140  represented in  FIGS. 11 and 12  is identical in construction and function to the first form of construction represented in  FIGS. 3 ,  4   6  and  7 , to the previous description of which reference is made in this respect. 
         [0179]    There now follows a description of the construction and function of the high mobile cooling station  132  with reference to  FIGS. 13 to 18 . 
         [0180]    The high mobile cooling station  132  comprises a substantially cuboidal housing  292  having a thermally insulated vertical left side wall  294   a , a thermally insulated vertical right side wall  294   b , a thermally insulated vertical back wall  296  that connects the two side walls at their rear ends to one another, and a thermally insulated horizontal top wall  298  that rests on the top edges of the side walls  294   a ,  294   b  and the back wall  296 . 
         [0181]    The housing  292  therefore on four sides, namely on the left, right, rear and top, surrounds a receiving space  300  for receiving a mobile frame  302  in the form of a high rack trolley  130 . 
         [0182]    The housing  292  of the high mobile cooling station  132  has neither a bottom wall nor a front wall, with the result that the receiving space  300  is open in a downward and forward direction and the high rack trolley may be introduced from the front into the receiving space  300 . 
         [0183]    The housing  292  is provided at its underside with a plurality of—for example four—castors  304 , by means of which the high mobile cooling station  132  may be moved over a floor. 
         [0184]    The left side wall  294   a  of the housing  292  at its inner side facing the receiving space  300  is provided with an outlet-side air baffle  306 , which comprises a plurality of—for example two—rows of outlet openings  308  extending over substantially the entire height of the side wall  294   a.    
         [0185]    In a corresponding manner, the right side wall  294   b  of the housing  292  at its inner side facing the receiving space  300  is provided with an intake-side air baffle  310 , which comprises a plurality of—for example two—rows of intake openings extending over substantially the entire height of the right side wall  294   b.    
         [0186]    There is further disposed at the front end face of the right side wall  294   b  a switch  312  for switching on and off the circulating-air cooling device, yet to be described below, of the high mobile cooling station  132 . 
         [0187]    As an alternative to such a manually actuable switch  312  it may also be provided that the high mobile cooling station  132  has a magnetically operated switch comprising a reed contact, which, after a rack trolley  130  has been introduced, owing to the presence of a magnet disposed on the rack trolley  130  closes an electrical contact and hence activates the circulating-air cooling device of the high mobile cooling station  132 . 
         [0188]    The circulating-air cooling device of the high mobile cooling station  132  is disposed in the back wall  296  thereof and comprises a plurality of—for example four—circulating-air fans  314  as well as, downstream thereof, a cooler  316  in the form of a heat exchanger, which comprises a cooler pack of one or more cooling coils  318 , through which binary ice may flow and which are connected by a binary-ice inlet pipe  320  to a binary-ice inlet connection  322  and by a binary-ice return pipe  324  to a binary-ice return connection  326 . 
         [0189]    The binary-ice inlet connection  322  is disposed on the outside of the right side wall  294   b , takes the form of a quick-action stop valve and is connectable to the binary-ice inlet line  184  of a consumer circuit  174  of the binary-ice supply system  144  that is associated with the high mobile cooling station  132 . 
         [0190]    The binary-ice return connection  326  is likewise disposed on the outside of the right side wall  294   b , takes the form of a quick-action stop valve and is connectable to the binary-ice return line  186  of the consumer circuit  174  of the binary-ice supply system  144  that is associated with the high mobile cooling station  132 . 
         [0191]    As the high mobile cooling station  132  is movable on the castors  304 , the binary-ice inlet line  184  and the binary-ice return line  186  of the consumer circuit  174  associated with the high mobile cooling station  132  are preferably of a flexible design to allow the high mobile cooling station  132  to be disposed in different positions relative to the circulation line  170  of the secondary circuit  168  of the binary-ice supply system  144 . 
         [0192]    Below the cooler  316  a water condensate collecting tank  328  is suspended from the back wall  296  of the housing  292  of the high mobile cooling station  132  and receives water condensate, which has condensed at the cooler  316 , and may for example take the form of a Gastronorm food container. 
         [0193]    The high rack trolley  130  to be inserted into the receiving space  300  of the high mobile cooling station  132  is represented individually in  FIG. 15 . 
         [0194]    The rack trolley  130  comprises a first frame  330   a  and a second frame  330   b , each of which is composed of two vertical members  332  and three horizontal members  334  that connect the two vertical members  332  to one another, as well as a number of horizontal suspension rails  336 , which connect in each case a vertical member  332  of the first frame  330   a  and the second frame  330   b  to one another and lie opposite one another in pairs and from which trays and/or food containers and/or drinks containers may be suspended. 
         [0195]    A castor  350  is disposed on the bottom end of each of the vertical members  332  to allow the high rack trolley  130  to be moved over a floor. 
         [0196]    The high rack trolley  130  is loaded with the product to be cooled and stored temporarily in a refrigerator room or cold store. 
         [0197]    For portioning, the high rack trolley  130  with the product to be cooled disposed thereon is moved from the refrigerator room and/or cold store to the food conveyor belt  102  and introduced into the receiving space  300  of the high mobile cooling station  132 . 
         [0198]    After activation of the circulating air cooling of the high mobile cooling station  132  by means of the switch  312 , the circulating-air fans  314  generate a circulating air flow that is cooled by means of the cooler  316 . 
         [0199]    As may be seen from  FIGS. 17 and 18 , in which the circulating air flow is diagrammatically represented by the arrows  329 , the cooled circulating air passes from the cooler  316  into the left side wall  294   a , from there through the outlet openings  308  in the outlet-side air baffle  306  into the receiving space  300  and hence to the product to be cooled, which is suspended from the high rack trolley  130 , from the receiving space  300  through the intake openings in the intake-side air baffle  319  into the right side wall  294   b  of the housing  292  of the high mobile cooling station  132  and, from there, back to the circulating-air fans  314 , with the result that the circulating air circuit is closed. 
         [0200]    By means of the cold-air curtain thus generated in the receiving space  300  the product to be cooled, which is suspended from the high rack trolley  130 , is screened off from the warm environment. 
         [0201]    The high rack trolley  130  inserted into the receiving space  300  is moreover screened off from the warmer surrounding area on four sides, namely on the left, at the rear, on the right and at the top, by means of the thermally insulated walls  294   a ,  294   b ,  296  and  298  of the housing  292  of the high mobile cooling station  132 . 
         [0202]    From the front of the high mobile cooling station  132 , however, the high rack trolley  130  is freely accessible for the removal of cooled product by an operator, thereby allowing an ergonomic operation. 
         [0203]    The low mobile cooling station  124  represented in  FIGS. 19 to 21  differs from the high mobile cooling station  132  represented in  FIGS. 13 to 18  in that it has no top wall, so that the low mobile cooling station  124  surrounds the low rack trolley  122  to be introduced into the receiving space  300  of the low mobile cooling station  124  only on three sides, namely on the left, on the right and at the rear, while the inserted rack trolley  122  is freely accessible at the front and at the top for the removal of cooled product by an operator. 
         [0204]    In the low mobile cooling station  124 , moreover, the cooled circulating air is blown through outlet openings  338  in both side walls  294   a  and  294   b  into the receiving space  300  and hence, when the rack trolley  122  is inserted, onto the product to be cooled and is extracted from the receiving space  300  through intake openings  340  at the inside of the back wall  296  (see  FIG. 21 , in which the circulating air flow is diagrammatically represented by the arrows  329 ). 
         [0205]    In the back wall  296  of the housing  292  of the low mobile cooling station  124  there are accordingly two circulating-air cooling devices each comprising circulating-air fans and a cooler, namely one circulating-air cooling device between the intake openings  340  and the outlet openings  338  of the left side wall  294   a  and one circulating-air cooling device between the intake openings  340  and the outlet openings  338  in the right side wall  294   b.    
         [0206]    The low rack trolley  122  to be inserted into the low mobile cooling station  124  is represented individually in  FIG. 20  and comprises a first frame  342   a  and a second frame  342   b , which are each composed of two horizontal members  344  and four vertical members  346  connecting the horizontal members  344  to one another, as well as a multiplicity of suspension rails  348 , which connect the first frame  342   a  and the second frame  342   b  to one another and lie opposite one another in each case in pairs and are used to suspend trays, food containers and/or drinks containers. 
         [0207]    On its underside the rack trolley  122  is provided with four castors  350 , by means of which the rack trolley  122  is movable over a floor. 
         [0208]    On its upper side the rack trolley  122  carries a stand  352  comprising a lay-on frame  354  inclined relative to the horizontal for supporting trays, food containers and/or drinks containers in a position inclined relative to the horizontal, thereby facilitating the removal of cooled food and/or drinks from the containers supported on the lay-on frame  354 . 
         [0209]    Otherwise the low mobile cooling station  124  represented in  FIGS. 19 to 21  is identical in construction and function to the high mobile cooling station  124  represented in  FIGS. 13 to 18 , to the previous description of which reference is made in this respect.