Patent Publication Number: US-2019178506-A1

Title: Cooling device for installation under a room ceiling

Description:
The invention concerns an air cooler according to the preamble of claim  1  and a method for cooling of the air in rooms, especially in walk-in storage or cooling rooms. 
     Generic air coolers are used, for example, for cooling of air in large-volume rooms, like walk-in storage or cooling rooms. The air coolers used for this purpose are part of the equipment of the storage or cooling room and are installed stationary in it. The air cooler contains a heat transfer device, for example, in the form of a heat exchanger, past which or through which the air being cooled is guided, in which case the heat exchanger withdraws heat from the air and cools it. The heat transfer device can be a heat exchanger having a tube or channel system traversed by a coolant or refrigerant. The heat transfer device can also be an evaporator having a tube or channel system traversed by a two-phase refrigerant. The tube or channel system of the evaporator is then connected to a condenser or recooler that is normally arranged outside the room being cooled, for example, on the roof of the building in which the storage or cooling room is located. The refrigerant is then only filled into the condenser or recooler after installation of the cooling system, consisting of the air cooler arranged in the storage or cooling room and the external condenser or recooler. The condenser or recooler is connected via pipelines to the evaporator of the air cooler in order to guide the refrigerant in a liquid state under low pressure through the evaporator. When the room air of the storage or cooling room being cooled flows through the evaporator, the initially liquid refrigerant evaporates and removes heat from the traversing air. The evaporated refrigerant is returned via the pipeline to the condenser or recooler to be liquefied and cooled there by compression. 
     An air conditioner is known from JP 2009 024 936 A, having a housing installable on a ceiling in which a radial fan is arranged. The radial fan draws in surrounding air through an air inlet arranged on the bottom of the housing and blows out the drawn-in air in the radial direction through air outlets arranged laterally in the housing. A heat exchanger is arranged in each of the air outlets, through which the air blown out by the radial fan is guided and cooled. The radial fan and the heat exchanger are then situated at the same height with the air outlets arranged laterally in the housing. 
     Another air conditioner of this type is known from JP 06 137 558 A. This air conditioner also comprises a housing installable on a ceiling in which a diagonal fan and a heat exchanger are arranged. The diagonal fan draws in the surrounding air through a suction opening arranged on the bottom of the housing in which the heat exchanger is arranged. The drawn-in air flows through the essentially horizontal heat exchanger that is designed flat and is cooled in so doing. The drawn-in and cooled air is guided obliquely upward by the diagonal fan and deflected by guide elements obliquely downward in the direction of air outlets arranged laterally in the housing. The cooled air flows back into the room through the air outlets. 
     These known air conditioners are generally used for air conditioning of smaller rooms, like residential and office rooms in order to produce a comfortable room temperature in the range from 20 to 25° C. When such air conditioners are used in large-volume storage or cooling rooms in which significantly lower cooling temperatures in the range below 16° C. are to be produced, there is a hazard that water from condensation will form in the air conditioner, especially on the pipelines and louvers, which can drip from the air conditioner. When a fan is arranged beneath the heat exchanger, the water drops of the condensation in the fan can be sprayed and blown out of the air outlets with the cooled air and produce unwanted drop discharge in the room. This can also happen when the fan is arranged above the heat exchanger, if the fan is operated at higher power (higher speed). 
     A cooling system for large-volume rooms, for example, for walk-in cooling and storage rooms, is known from US 2006/0130 517 A1, which includes an evaporation device arranged in the room being cooled and an external compressor connected to it via pipelines and a downstream compressor, which are arranged outside of the room being cooled. A refrigerant guided in a pipeline system is compressed in the external compressor and liquefied in the downstream condenser and then passed in the liquid state through the pipelines into the evaporation device. Before the refrigerant enters the evaporation device, the liquid refrigerant flows through an expansion valve in order to expand the refrigerant. The cooling system is then operated either with a one-phase or two-phase refrigerant, in which case the evaporator arrangement acts as a simple heat exchanger when the system is operated with a one-phase refrigerant and as an evaporator when it is operated with a two-phase refrigerant, in which the refrigerant expanded by the expansion valve evaporates and, after having been heated by the surrounding air flowing past, is fed back to the compressor in a gaseous state by the pipelines and liquefied there again. 
     The evaporator device then includes a housing in which two microchannel evaporators are arranged. A flat air inlet covered by an air grate and also a flat air outlet covered by an air grate are arranged in the housing, the air inlet and the air outlet being arranged in opposite walls of the housing and the microchannel evaporator in between. Several fans are also arranged in the housing, which are connected to the microchannel evaporators in order to guide air through the evaporator device. For this purpose, surrounding air is drawn in through the air inlet and blown out of the housing through the air outlet. The surrounding air drawn-in by the fans is passed by or through the microchannel evaporators, cooling the air. The housing of the evaporator device can then be set up in the walk-in storage or cooling room or arranged suspended from the ceiling so that a free space remains between the ceiling and the top of the housing that permits inflow or outflow of air. Setting up the housing on the floor of the storage or cooling room being cooled, however, requires considerable space that is no longer available as storage space. A suspension arrangement of the evaporator device from the ceiling of the walk-in storage or cooling room has the drawback that dust and dirt can accumulate on the horizontally lying top of the housing on which the air inlet or air outlet is arranged. This is particularly problematical in storage and cooling rooms for foods, since the product being stored can be soiled, producing a hygiene problem. In addition, the condensation water in this evaporator device that precipitates on the pipelines and louvers on the microchannel evaporators can drip out through the air outlet (or air inlet). 
     Starting from this, the underlying task of the invention is to provide a highly efficient air cooler for cooling of the air in large-volume and especially walk-in storage or cooling rooms, having a housing that is arranged on a ceiling of the room being cooled and avoids the mentioned drawbacks of the cooling devices known from the prior art and especially dripping of condensation and accumulation of dust and dirt on the top of the cooling equipment suspended from the ceiling. The air cooler should be installable in space-saving fashion in the room being cooled and be as low as possible in order to permit installation on the ceiling without significantly reducing the room height. 
     This task is solved with an air cooler with the features of claim  1  and with the method for cooling of air in rooms with the features of claim  14 . Preferred practical examples of the air cooler according to the invention are apparent from the dependent claims. 
     The air cooler according to the invention includes a housing with a bottom, a cover that can be fastened directly without spacing to a ceiling of the room being cooled, and at least one side wall in which at least one air outlet is arranged, as well as at least one essentially horizontal heat exchanger designed flat and arranged in the housing and at least one fan arranged in the housing above the heat exchanger. The fan draws in surrounding air from the room being cooled through an air inlet and the drawn-in air flows essentially vertically through the flat heat exchanger and is deflected by the fan in a horizontal direction to the air outlet arranged in the side wall of the housing. The fan and the air outlet are then situated according to the invention above the heat exchanger. 
     Through this arrangement it is possible for the drawn-in air to flow through the flat heat exchanger essentially perpendicular to its plane and to leave the housing through the at least one laterally arranged air outlet and flow back into the room. A large effective heat transfer surface and therefore good heat transfer efficiency is guaranteed by this design. A vertical air stream of the cooled air from the housing into the room being cooled is also prevented because the cooled air leaves the housing through at least one lateral air outlet in an essentially horizontal flow direction. This prevents unpleasant vertical air flows in the room being cooled and permits uniform distribution of cooled air in the room. 
     Direct arrangement of the cover of the housing on the ceiling of the room being cooled without spacing between the room ceiling and the cover of the housing prevents dust and dirt from being deposited on the top of the cover. 
     The arrangement of the fan according to the invention, at least at one air outlet and the heat exchanger in the housing of the air cooler also permits arrangement of a trough for collection of condensation that can form on the outer surface of the heat exchanger especially on the louvers and pipelines of a finned coil heat exchanger or microchannel evaporator. For this purpose, a recess is expediently formed in the bottom of the housing, or a collection trough is arranged on the bottom in the interior of the housing. The condensation that forms on the outer surface of the heat exchanger and drips off because of gravity can be collected in the recess of the bottom or in the collection trough arranged on the bottom and taken off through a discharge line that discharges at the lowest point of the recess or collection trough. 
     The air inlet through which the surrounding air is drawn in by the fan into the interior of the housing is expediently arranged beneath the heat exchanger and, like the at least one air outlet, in a side wall of the housing. On the one hand, this guarantees that all of the surrounding air flowing into the housing is passed through the heat exchanger so that very efficient heat transfer can be produced. On the other hand, arrangement of the at least one air inlet in a side wall of the housing prevents unpleasant air flows in the room being cooled in the vertical direction. Several air inlets and several air outlets are expediently provided in the housing. 
     The housing can then be designed as a cylinder and have a side wall with a curved surface. It is expedient in this practical example of the air cooler according to the invention to provide the air inlet and air outlet at diametrically opposite locations of the curved side wall. When there are several air inlets and air outlets, they are expediently arranged alternating and uniformly around the periphery of the side wall of the cylindrical housing. 
     The housing can also be designed a cuboid with four side walls perpendicular to each other, in which case no air inlet is expediently arranged in each side wall in which an air outlet is provided and vice versa. This prevents already cooled air leaving the housing through an air outlet from being drawn in directly to the housing by an air inlet arranged adjacent to the air outlet. 
     A separating plate, in which an air passage opening is formed, is preferably arranged between the flat and at essentially horizontally lying heat exchanger and the fan. The air passage opening in the separating plate is then flush with the fan, i.e., the air passage opening runs coaxial to the axis of rotation of the fan and the diameter of the air passage opening corresponds essentially to the diameter of the fan, which typically can lie in the range from 200 to 400 mm, but also be as much as 1200 mm. The surrounding air drawn in by the fan through the air inlet then flows essentially in the horizontal direction into the housing and is deflected there by the partial vacuum produced by the fan in the region above the separating plate in the vertical direction and initially flows through the flat heat exchanger and then into the fan through the air passage opening in the separating plate. The separating plate divides the interior of the housing into a horizontal plane and makes sure that the surrounding air drawn in by the fan can flow essentially fully in the vertical direction through the flat heat exchangers. Decoupling of the flow of the drawn-in surrounding air in the vertical direction to the heat exchanger and outflow of the cooled air in an essentially horizontal flow direction through the at least one air outlet is ensured by dividing the interior of the housing with the separating plate. Air eddies in the interior of the housing and, as a result, a reduction of heat transfer efficiency can be avoided by this design. 
     The heat exchanger can be designed as a microchannel evaporator as in US 2006/0130517 A1 or as an alternative, as a finned coil heat exchanger. In both cases the drawn-in air flows parallel to the louvers of the heat exchanger or evaporator, namely in the case of a finned coil heat exchanger parallel to the louvers of the heat exchanger and in the case of a microchannel evaporator parallel to the louvers arranged in zig-zag between the parallel microchannels of the microchannel evaporator. In both cases the drawn-in air flows perpendicular to the flow direction of the refrigerant flowing through the tubes or channels of the heat exchanger. A large heat transfer surface and therefore efficient heat transfer are also ensured by this design. 
    
    
     
       These and additional features and advantages of the invention are apparent from the following practical examples further described with reference to the accompanying drawings. The drawings show: 
         FIG. 1 : perspective view of a first embodiment of an air cooler according to the invention with a housing and a fan arranged in it and a heat transfer device designed as a heat exchanger, the front side wall of the housing being removed to depict the housing interior; 
         FIG. 2 : front view of the embodiment of an air cooler according to the invention of  FIG. 1 ; 
         FIG. 3 : perspective detail view of the heat exchanger and fan of the embodiment of the air cooler of  FIG. 1 , in which the front and rear side wall and the cover of the housing and a separating plate are not shown for better depiction; 
         FIG. 4 : perspective detail view of the cover and upper section of the lateral side walls of the housing with a horizontal separating plate of the embodiment of the air cooler of  FIG. 1 , in which the heat exchanger is not shown for better depiction; 
         FIG. 5 : perspective detail view of the heat exchanger of the embodiment of the air cooler in  FIG. 1  ( FIG. 5 a   ) and schematic view of air flow through the heat exchanger ( FIG. 5 b   ); 
         FIG. 6 : perspective view of a second embodiment of an air cooler according to the invention with a heat exchanger designed as an evaporator, the front side wall of the housing being removed to depict the housing interior; 
         FIG. 7 : front view of an embodiment of an air cooler according to the invention modified relative to the embodiment of  FIG. 6  with a trough for collection of condensation; 
         FIG. 8 : perspective detail view of the heat exchanger designed as an evaporator of the embodiment of the air cooler of  FIGS. 6 and 7 . 
     
    
    
     The practical example depicted in  FIGS. 1 to 5  of an air cooler for cooling of the air in large-volume rooms, especially in walk-in storage and cooling rooms or cooled work rooms (especially in the food industry, for example, in slaughterhouses), comprises a cuboid housing  1  with a horizontal bottom  1   a,  a cover  1   b  arranged parallel and at a spacing to it and four side walls  1   c  perpendicular to each other and to the floor and cover. A fan  4  and a heat exchanger  3  are arranged in housing  1 , the heat transfer device  3  being designed as a heat exchanger in the practical example of  FIGS. 1 to 5 . The flat heat exchanger, which is depicted in  FIGS. 3 and 5  in a perspective view in detail, is arranged in the interior of the housing in a horizontal position. The fan  4  can be a radial or diagonal fan. 
     Cover  1   b  can be directly fastened without spacing to a ceiling of the room being cooled so that the air cooler can be arranged without spacing between the ceiling. This can occur, for example, by fastening the cover  1   b  by fasteners or a frame to the bottom of the ceiling. 
     The interior of the housing  1  is divided by a horizontal separating plate  6  into a lower space and upper space, the fan  4  being arranged in the upper space above the separating plate  6  and the heat exchanger  3  in the lower space beneath the separating plate  6 . A circular air passage opening  6   a  is provided in the center of the separating plate  6 , which is flush with the fan  4  arranged above it so that the air passage opening  6   a  is arranged coaxial to the axis of rotation of the fan  4  and has a diameter corresponding essentially to the diameter of fan  4 . 
     The air inlets  5  are provided in the lower space of the housing  1  on the opposite side walls  1   c.  The air inlets  5  are formed by openings in the side walls  1   c.  An air filter  9  is arranged expediently in each of these openings. 
     The air outlets  2  are also provided in the upper space of the housing  1  in the opposite side walls  1   c  in the form of openings in the side walls  1   c.  On the outside of the housing in the area of the air outlets  2 , several guide slats  10  or jalousie louvers are arranged parallel one above the other at a spacing and they point obliquely downward. The guide slats or jalousie louvers are preferably movable and expediently motor-driven so that they can be closed, for example, during a thawing process. 
     The bottom  1   a  contains a spherical recess diminishing toward the center, whose deepest point discharges into a discharge line now shown here. 
     The heat transfer device  3  designed as a heat exchanger in this practical example is shown in detail in  FIGS. 3 and 5  and includes distributor lines  3   c,  which run parallel to the side wall  1   c  of housing  1  along an x direction and are connected to transverse lines  3   b  arranged perpendicular to them (as shown in  FIG. 5 a   ). The transverse lines  3   b  run along a z direction. The louvers  3   a  are arranged across the transverse lines  3   b,  which run in an x-y plane and are arranged in the z direction at a spacing from each other. A coolant, for example, a glycol-containing coolant, is guided by the distributor lines  3   c  and transverse lines  3   b.  The distributor lines  3   c  are connected for this purpose to a coolant loop, via which cooled coolant is guided in transverse lines  3   b  and returns from there for recooling. The coolant loop contains a recooler for cooling of the coolant, which is expediently arranged outside the room being cooled, for example, on a building roof. 
     For cooling of the air in the storage or cooling room in which the air cooler is arranged, surrounding air is drawn in through the air inlets  5  by means of the rotating fan  4 . The drawn-in air flows in an essentially horizontally running inlet flow through the air inlets  5  into the lower space of the housing  1  and because of the partial vacuum generated by the fan  4  in the upper space in at least an essentially vertical direction through a heat exchanger  3 . When the drawn-in air flows through the heat exchanger  3 , heat is removed from the air so that the air is cooled. The heat withdrawn from the air is taken up by the coolant circulating in the heat exchanger and transported away to the recooler in order to recool the heated coolant coming from the heat exchanger  3 . 
     The air stream through the heat exchanger  3  designed as a finned coil heat exchanger is schematically depicted in  FIG. 5 b   . The air drawn into the interior of the housing  1  flows in a vertical direction (y direction) through the flat heat exchanger  3  and then flows past the transverse lines  3   b,  through which the (cold) coolant flows. The louvers  3   a  arranged across the transverse lines  3   b,  which are formed from a heat-conducting material, like metal, preferably aluminum, as are the pipelines of the distributor and transverse lines, then increase the effective heat transfer surface between the air stream being cooled and the pipelines of the exchanger  3 . The air then flows perpendicular to the flow direction of the coolant flowing through the transverse lines  3   b.    
     After flowing through the heat exchanger  3 , the cooled air flows through the air passage opening  6   a  in the separating plate  6  into the upper space of housing  1  and is deflected there in a horizontal direction by the fan  4 . The cooled air deflected in the horizontal direction finally flows in an essentially horizontal outlet flow through the air outlets  2  from the housing  1  and is then deflected obliquely downward by the guide slats  10 . 
     Condensation, which can form on the pipelines and louvers of the heat exchanger  3 , drips off by gravity and can collect in the recess of the bottom  1   a  and be taken off through the discharge line. 
     The upper part of housing  1  is depicted in  FIG. 4  in a perspective view, the front side wall being removed for clarification. The horizontal separating plate  6  with the central air passage opening  6   a  and the fan  4  arranged above it are apparent from  FIG. 4 . The heat exchanger arranged beneath separating plate  6  is not shown in the depiction of  FIG. 4  for reasons of clarity. The inward protruding support plates  11  are formed on the side walls  1   c  for fastening of the heat exchanger  3  on the housing  1 . The lateral edge areas of the heat exchanger  3 , and especially its distribution lines  3   c,  can be positioned and fastened on these support plates  11  in order to hold the heat exchanger  3  in the essentially horizontal position. 
     Another practical example of an air cooler according to the invention is depicted in  FIG. 6 , this practical example corresponding to the practical example of  FIGS. 1 to 5 , except for the heat exchanger  3 . The heat exchanger  3  in the practical example of  FIG. 6  is designed as an evaporator and especially as a microchannel evaporator. The heat exchanger  3  designed as a microchannel evaporator of the practical example of  FIG. 6  is shown in  FIG. 8  in detail. It includes the lateral distributor tubes  3   c  running parallel at a spacing from each other along the x direction, which are connected to a number of flat transverse channels  3   d  running perpendicular to them (in the z direction). The transverse channels  3   d  are divided in the interior into several (for example, 10 to 15) microchannels, each of which have a diameter or height/width of 1 to 2 mm. A two-phase refrigerant is guided in the microchannels of the transverse channels  3   d  via the distributor tubes  3   c.  The zig-zag louvers  3   e  are arranged between the transverse channels  3   d  arranged in the x direction at a spacing from each other. The distributor tubes  3   c  are connected via a pipeline system to an external compressor and a subsequent condenser, both of which are arranged outside of the room being cooled, for example, on a building roof. The refrigerant is compressed in the compressor and liquefied in the subsequent condenser and guided to the heat exchanger  3  via the pipeline system. An expansion valve is arranged upstream of the heat exchanger  3  so that the transported and initially liquid refrigerant can expand and evaporate. When the expanded refrigerant passes through the microchannels of the microchannel evaporator, the refrigerant evaporates and absorbs heat from the air flowing through the heat exchanger  3 . The air then flows in the vertical direction (y direction) parallel to the louvers  3   e  through the microchannel evaporator and is cooled by releasing heat to the heat exchanger  3 . The evaporated refrigerant of the microchannel evaporator flows back from the transverse channel  3   d  into a distributor line  3   c  and is returned from there via the pipeline system to the compressor and the subsequent condenser, in order to be compressed and liquefied again. 
     In order for an oil contained in the employed refrigerant (which is required for lubrication of the compressor) to be discharged from the pipelines and microchannel evaporator and especially from the microchannels of the transverse lines  3   b  during replacement of the refrigerant, it is expedient in this practical example to position the flat heat exchanger  3  not precisely in a horizontal position, but to maintain a slight slope relative to the horizontal of about 1 to 3°. A slight slope of the heat exchanger  3  relative to the horizontal is also recommended during use of a heat exchanger as a heat transfer device, if this is operated with a two-phase oil-containing refrigerant that is compressed in an external compressor arranged downstream. 
     A modified variant of the practical example of  FIG. 6  is shown in  FIG. 7 . Like the air cooler of  FIG. 6 , the air cooler of the practical example of  FIG. 7  also has a heat exchanger  3  designed as a microchannel evaporator. Unlike the practical example of  FIG. 6 , in which a recess is formed in the bottom  1   a  (as in the practical example of  FIG. 1 ) for collection of condensation, the practical example of  FIG. 7  contains a collection trough  8 , in which the condensation can be collected. The collection trough  8  is expediently sloped slightly relative to the horizontal, for example, in the angle range from 1 to 5°. The collection trough  8  contains on a sloped side a discharge line  12 , via which the collected condensation can be taken off, especially drawn off. The collection trough is expediently dimensioned so that it covers or protrudes beyond the outline of the heat exchanger arranged above it so that any condensation that drips off on the pipelines and louvers of the heat exchanger can be fully collected. 
     The invention is not restricted to the practical examples depicted in the drawings. For example, a fin-and-tube heat exchanger or evaporator can be used as the heat transfer device instead of a microchannel evaporator. The heat exchanger according to the above practical examples can then be flat or even bent, especially concave. Several fans and heat exchangers can also be arranged in housing  1 , in which case a heat exchanger and a fan could expediently be arranged one above the other in alternation (from the bottom up). 
     The air coolers according to the invention are expediently dimensioned so that they produce a heat output in the range&gt;1 kW. Room temperatures in the range from 4 to 16° C. can therefore be achieved.