Abstract:
An apparatus ( 10 ) for cooling and/or for heat recovery, the apparatus ( 10 ) being expandable in modular fashion in a simple manner without thereby prejudicing efficiency. For this purpose, the invention envisages forming an apparatus ( 10 ) from a plurality of heat exchanger modules ( 11 ) that can be assembled together, each having a heat exchanger.

Description:
STATEMENT OF RELATED APPLICATIONS 
       [0001]    This patent application is the National Phase of International Patent Application No. PCT/EP2013/000403 having an International Filing Date of 12 Feb. 2013, which claims the benefit of German Patent Application No. 10 2012 003 068.1 having a filing date of 17 Feb. 2012 and German Patent Application No. 10 2012 004 900.5 having a filing date of 9 Mar. 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The invention relates to an apparatus for cooling and/or for heat recovery having at least one heat exchanger and an apparatus for indirect evaporative cooling having at least one heat exchanger, which has a plurality of heat exchanger plates and a device for wetting the heat exchanger plates. 
         [0004]    2. Prior Art 
         [0005]    The present invention is concerned with an apparatus for cooling and/or for heat recovery having at least one heat exchanger for gaseous media. The heat exchanger has a primary flow channel and a secondary flow channel, which are physically separated but thermally coupled. Two media are passed through these channels, preferably in crossflow or counterflow. During this process, energy in the form of heat is exchanged between the two media. 
         [0006]    One of said channels of the heat exchanger, the secondary channel, has a hydrophilic coating on the walls, i.e. has the capacity to absorb a liquid medium, e.g. water, by capillary action and to release it again by evaporation. The heat of evaporation required to evaporate liquid from the hydrophilic layer is taken from the medium in the adjacent primary channel. The medium in the primary channel is thus cooled through the removal of heat. This process is referred to as indirect evaporative cooling and is used in many heat exchangers. 
         [0007]    Critical consideration of this type of construction shows that the counterflow heat exchanger is composed of a part in which the media do in fact move in counterflow to one another and a part in which the media move in crossflow relative to one another. The crossflow/counterflow ratio in counterflow heat exchangers is therefore very important as regards efficiency. A high efficiency has a major effect on the action of the heat exchanger in terms of heat recovery and cooling if said heat exchanger is used as a cooler. 
         [0008]    Counterflow heat exchangers up to an air volume flow of 1500 m 3 /h, in which the pressure loss across the channels is no more than about 150 Pa, are known. If the geometry of such heat exchangers were scaled up in such a way that they were theoretically suitable for air volume flows of, for example, 10,000 m 3 /h, the resulting ratio of crossflow to counterflow would be very unfavorable. The proportion of crossflow would be much greater than the proportion of counterflow, and this would prejudice efficiency. Another disadvantage is that the distance between the plates would have to be increased greatly in order to keep the pressure loss within limits, and this would likewise have a disadvantageous effect on the efficiency of the heat exchanger. Moreover, a major disadvantage is that it is almost impossible to fully wet the secondary channels with the liquid to be evaporated. This further reduces the efficiency of an evaporative cooler. 
         [0009]    Counterflow heat exchangers of the type mentioned, which are suitable for air volume flows of 1500 m 3 /h, can also be positioned adjacent to one another, making the overall width of the plate assembly greater, but this is possible to only a limited extent because, otherwise, the housing in which the counterflow heat exchangers were set up would be much too wide. 
         [0010]    Calculations according to the applicable aerodynamic principles show that the percentage of the counterflow portion in respect of the total surface area of a small heat exchanger is much greater and, accordingly, more favorable in the case of small dimensions than in the case of heat exchangers with large dimensions. The calculations furthermore show that the plate spacing for a large heat exchanger would have to be much larger than for smaller heat exchangers since the pressure loss between the plates would otherwise be too high and the heat exchanger could only be operated inefficiently. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    It is the underlying object of the invention to provide an apparatus for cooling and/or for heat recovery which allows a high capacity with a relatively high efficiency and furthermore has a simple construction. 
         [0012]    An apparatus for achieving this object is an apparatus for cooling and/or for heat recovery having at least one heat exchanger, characterized by a plurality of heat exchanger modules which can be assembled together, which each have a heat exchanger, and the heat exchanger modules can be assembled together in such a way that the heat exchangers thereof can be operated in parallel. According to this, the apparatus for cooling and/or for heat recovery is formed by means of a plurality of heat exchanger modules which can be assembled together, which each have a heat exchanger. By assembling together a plurality of heat exchanger modules, each having its own heat exchanger, a larger heat exchanger with a higher cooling capacity or heat recovery capacity is provided. Here, there is a linear relationship between the increase in capacity and the number of individual heat exchanger modules assembled together. Assembling a large heat exchanger in modular fashion from a plurality of smaller heat exchangers ensures that the geometry of the heat exchangers, in particular the aerodynamic properties of the heat exchangers, are unaffected. This absence of an effect on the flow properties of the heat exchangers of the heat exchanger modules means that it is possible to produce heat exchangers of any desired size which have the same effectiveness or the same efficiency as small heat exchangers. 
         [0013]    Assembling the heat exchanger modules together in modular fashion to give an apparatus for cooling or for heat recovery enables the size of the heat exchangers to be adapted to the cooling capacity or heat recovery capacity that is actually required. An apparatus with the desired cooling and/or heat recovery capacity can thus be assembled together from a correspondingly large number of heat exchanger modules, and there is no limit to the number of heat exchanger modules. 
         [0014]    It is furthermore envisaged that the heat exchanger modules can be assembled together in such a way that the heat exchangers thereof can be operated in parallel. Operating the heat exchanger modules in parallel is advantageous particularly for supply air lines and exhaust air lines for the individual heat exchangers since, in this way, only one line is required for each supply air line and exhaust air line of all the heat exchanger modules. In particular, operation of the apparatus is not interrupted if one heat exchanger module is faulty, as can be the case with heat exchangers connected in series. The loss of capacity can simply be compensated for by the other heat exchanger modules. 
         [0015]    A development of the apparatus envisages that the plurality of heat exchanger modules can be coupled together, preferably stacked together, vertically one above the other and/or horizontally adjacent to one another. The invention envisages that the individual heat exchanger modules can be coupled together. This coupling together can take place vertically one above the other or horizontally adjacent to one another, depending on the spatial conditions. Moreover, it is conceivable for coupling to be both vertical and horizontal. By means of this coupling together, all the thermodynamic properties of the individual heat exchanger module are scaled up or multiplied proportionally to the number of heat exchanger modules used. 
         [0016]    Provision is preferably made for each heat exchanger module to have at least one air inlet opening, preferably two air inlet openings and at least one air outlet opening, preferably two air outlet openings. If the heat exchanger is operated by the counterflow method, a secondary flow cools at least one heat exchanger plate of the heat exchanger by means of a coolant. A primary flow carrying fresh air is routed past the at least one heat exchanger plate, whereupon the fresh air cools down. To ensure that unintended humidification of the fresh air and turbulence do not occur, both the primary and the secondary flow run in a dedicated channel. Each of these two channels therefore requires an opening and an outlet. It is also conceivable for the heat exchanger to have more than two channels. 
         [0017]    In the apparatus according to the invention, provision is made, in particular, for the air inlet openings and the air outlet openings of successive heat exchanger modules to be situated one above the other and for the heat exchanger modules to have a common supply air duct and a common exhaust air duct. The fact that the air inlet openings and the air outlet openings of the successive heat exchanger modules are situated one above the other enables the respective openings to be combined into a unit. This makes it possible for the common supply air duct and the common exhaust air duct each to consist of one component. 
         [0018]    A particularly advantageous development of the apparatus envisages that the air inlet openings and the air outlet openings of successive heat exchanger modules can be supplied in the same way, preferably in parallel, by the common exhaust air duct and the common supply air duct. For this purpose, the exhaust air duct and the supply air duct are connected directly in the same way to all the air inlet openings or air outlet openings respectively. 
         [0019]    It is furthermore envisaged that each heat exchanger module has a means for wetting water feed and a means for wetting water discharge, wherein the means can preferably be connected by connecting or coupling together the heat exchanger modules. In particular, the means for wetting water feed can be a pipe that can be formed by individual pipe segments. In particular, the means for wetting water discharge can be a channel that can be assembled together from channel segments. The channel segments are each coupled to the heat exchanger modules by means of a drain opening. 
         [0020]    Moreover, a particularly advantageous embodiment of the apparatus is characterized in that the heat exchanger modules are assigned a common wetting water reservoir for wetting water, which has at least one pump, by means of which the wetting water from the wetting water reservoir can be fed to the heat exchanger modules and/or excess wetting water can be fed back to the wetting water reservoir. In this case, the wetting water reservoir can be designed as a trough which holds a supply of wetting water and/or collects the wetting water; or it can have a pipe in which the wetting water can be gathered directly and can be fed back to the heat exchanger modules by the pump. 
         [0021]    Provision is furthermore preferably made for the heat exchanger modules to have means for assembly involving interengagement. This makes it possible to assemble from the individual heat exchanger modules a heat exchanger with a capacity corresponding to the number of heat exchanger modules, in accordance with a “clamped module principle”. Any number of assembled heat exchanger modules is possible. 
         [0022]    As a particularly advantageous development of the invention, provision is made for the wetting water reservoir and each heat exchanger module to have a housing, which surrounds the heat exchanger and is preferably formed by identical housing halves. Forming the housing from identical housing halves gives the modular apparatus its flexibility. The housing halves are of a nature such that they can be assembled together, inserted one into the other and interchanged between different heat exchanger modules. Moreover, just one type of housing half is required to produce a heat exchanger of any desired size from the identical housing halves. 
         [0023]    Provision is furthermore preferably made for the housing halves of the heat exchanger modules and the wetting water reservoir each to have interengaging depressions and corresponding projections, by means of which the housing halves interengage and/or can be assembled positively. The interengagement of the depressions and of the corresponding projections ensures meshing of the housing halves, in particular of an upper and a lower joint surface and thereby prevents slipping of the housing halves relative to one another. 
         [0024]    The invention furthermore envisages that the heat exchanger modules, preferably all the heat exchanger modules, are jointly surrounded by a common housing. The apparatus formed by the sum of all the heat exchanger modules can be surrounded completely by a common housing. The common housing has a particularly soundproofing effect and collects any escaping moisture from the individual heat exchanger modules. In addition, it gives the common housing of the apparatus compactness. 
         [0025]    Another apparatus for independently achieving the object stated at the outset is an apparatus for indirect evaporative cooling having at least one heat exchanger, which has a plurality of heat exchanger plates and a device for wetting the heat exchanger plates, characterized in that the device is assigned at least one baffle surface in such a way that wetting water jets produced by the device impinge on the at least one baffle surface at an angle unequal to 90°. This can also be a preferred development of the apparatus as claimed in one of one of the claims. Accordingly, the apparatus is provided with at least one device for wetting the heat exchanger plates to which is assigned at least one baffle surface in such a way that wetting water jets produced by the device impinge on the at least one baffle surface at an angle unequal to 90°. The water of the wetting water jets rebounding from the baffle surface wets the plurality of heat exchanger plates uniformly, preferably with a kind of water veil. 
         [0026]    An advantageous development of the apparatus envisages that the at least one baffle surface is formed by an oblique partial area of a wall of the housing, preferably of a top wall of the upper housing half. It is furthermore particularly advantageous that the at least one baffle surface is oriented in such a way relative to the wetting water jets and to the upright heat exchanger plates that a wetting water curtain or veil from above, produced by the impact of the wetting water jets on the baffle surface, is aligned transversely to the heat exchanger plates. However, it is also possible for the baffle surface to be aligned in any other way. 
         [0027]    A preferred development of the apparatus mentioned at the outset envisages that the device for wetting the heat exchanger plates has at least one pipe extending transversely across the heat exchanger plates of the heat exchanger of each heat exchanger module and having a plurality of openings for producing the wetting water jets. The number of openings depends on the number of heat exchanger plates to be wetted and on the geometry of the heat exchanger and the distance between the pipe and the heat exchanger plates. The openings can be simple drillings in the pipe wall or individual nozzles. 
         [0028]    Provision is furthermore preferably made for the pipe for producing the wetting water jets to be designed as a lance, which is arranged underneath a top of an upper housing half in each heat exchanger module. However, it is also conceivable for the pipe to assume a configuration that differs from the shape of a lance, in particular a curved shape. By virtue of the fact that a lance for wetting the heat exchanger plates extends into each heat exchanger module, the heat exchanger plates of all the heat exchanger modules can be wetted singly and individually. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    A preferred illustrative embodiment of the invention is explained in greater detail below by means of the drawing. In this drawing: 
           [0030]      FIG. 1  shows a schematic illustration of an apparatus for cooling having a plurality of heat exchanger modules, 
           [0031]      FIG. 2  shows the apparatus with heat exchanger modules stacked one above the other, 
           [0032]      FIG. 3  shows a heat exchanger module with a schematically illustrated primary flow, 
           [0033]      FIG. 4  shows a heat exchanger module with a schematically illustrated secondary flow, 
           [0034]      FIG. 5  shows a heat exchanger and two housing halves of a heat exchanger module, 
           [0035]      FIG. 6  shows a device for wetting the heat exchanger plates, in partial section, and 
           [0036]      FIG. 7  shows a wetting water reservoir in partial section. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]    The apparatus  10  illustrated in the drawing serves for cooling enclosed air or circulating air according to the evaporative principle, for example. The apparatus  10  can be assembled in a modular fashion from a plurality of individual identical heat exchanger modules  11 . Each heat exchanger module  11  has its own heat exchanger  29 . Thus, the apparatus  10  can be assembled from a corresponding number of (small) heat exchanger modules  11  in such a way that the cooling capacity of the apparatus  10  formed from a plurality of assembled heat exchanger modules  11  corresponds to the sum of the capacity of each individual heat exchanger module  11 . 
         [0038]    In the illustrative embodiment shown, the apparatus  10  is assembled from a plurality of box-shaped heat exchanger modules  11  stacked one above the other ( FIG. 1 ). The individual heat exchanger modules  11  are stacked congruently one above the other in such a way that a following heat exchanger module  11  is placed with its underside  50  on the upper side  12  of a preceding heat exchanger module  11 . The base of the apparatus  10  illustrated in  FIG. 1  is formed by a wetting water reservoir  27 . The heat exchanger modules  11  are stacked on the wetting water reservoir  27 . The heat exchanger modules  11  stacked one above the other and the wetting water reservoir  27  can be coupled together in such a way that together they form a unit. 
         [0039]    The individual heat exchanger modules  11  and the wetting water reservoir  27  each have a housing  13 . The housings  13  of all the heat exchanger modules  21  and the wetting water reservoir  27  are of identical design. The housings  13  of the heat exchanger modules  11  and of the wetting water reservoir  27  can be made of plastic or, alternatively, of sheet metal or aluminum. 
         [0040]    Each of the identical housings  13  is formed from two housing halves, namely a lower housing half  41  and an upper housing half  47 . In the illustrative embodiment shown, the housing halves  41  and  47  are of identical design and are assembled together in reverse with open ends facing one another to form the respective housing  13 . The housing  13  has a closed upper side  12 , a closed lower side and in each case two opposite closed side walls  14 . When the heat exchanger modules  11  are stacked one above the other, the individual side walls  14  of the housings  13  of the heat exchanger modules  11  together form a continuous surface  15  of the apparatus  10 . The opposite ends  16  of the heat exchanger modules  11 , which are only partially visible in  FIG. 1 , are partially open. 
         [0041]    At both opposite ends  16 , each housing  13  of a heat exchanger module  11  has an inlet  17  and an outlet  18  respectively. The inlet  17  and the outlet  18  form openings for air flows or gaseous media. In the illustrative embodiment shown in  FIG. 1 , the inlet  17  and the outlet  18  at an end  16  each occupy one quarter of the end  16 , i.e. exactly half the length and half the height thereof. The inlet  17  and the outlet  18  are positioned diagonally offset relative to one another at the end  16 . The corresponding other two quarters of the end  16  are closed. The opposite end  16  of the housing  13  from end  16  is an exact mirror image of the one just described. Separating plates  19  are arranged at the transitions between the inlets  17  and the outlets  18  on the two opposite ends  16  of the housing  13  of the heat exchanger module  11 . 
         [0042]    One inlet  17  and one outlet  18  in each case are situated diagonally opposite one another at opposite ends  16  of the housing  13  along the separating plates  19 . Thus, each end  16  of the housing  13  has one inlet  17  and one outlet  18 , which lie diagonally opposite the outlet  18  and the inlet  17  at the opposite end  16  of the housing  13 . One inlet  17  at one end  16  is thus in channel-type communication with one outlet  18  at the opposite end  16 . In this way, one inlet  17  at one end  16  is in each case connected in a channel-type manner with the corresponding outlet  18  at the other end  16 , and therefore the heat exchanger module  11  has two mutually separate channels. 
         [0043]    Since the two channels of a heat exchanger module  11  each connect two diagonally opposite openings (inlet  17  and outlet  18 ) and the inlets  17  and outlets  18  are situated opposite one another mirror-image fashion at the two ends  16 , the two channels cross along the plane of the separating plate  19 . Since the inlets  17  and outlets  18  of the channels are additionally situated at the opposite end, the heat exchanger  29  under consideration represents a cross-counterflow heat exchanger. 
         [0044]    In a cross-counterflow heat exchanger, air to be cooled, e.g. exterior air  42 , is passed through the heat exchanger  29  via a channel (primary channel) and is cooled at the heat exchanger plates  30  and fed back to a space to be air-conditioned as supply air  44 . The exhaust air  45  flows through the second channel (secondary channel) and is used to intensify the evaporation of the wetted inner walls of the secondary channel, and then leaves the heat exchanger as moist outgoing air  46 . The evaporation at the wetted inner walls of the secondary channel cools the heat exchanger plates and hence the primary channel. This process is referred to as indirect evaporative cooling. 
         [0045]    Since all the heat exchanger modules  11  are identical, the inlets  17  and outlets  18  at the ends  16  of the individual heat exchanger modules  11  are situated one above the other. The illustrative embodiment of the apparatus  10  shown in  FIG. 1  has at each end  16  an exhaust air channel  20  common to all the inlets  17  of the heat exchanger modules  11  and a supply air channel  21  common to all the outlets  18  of the heat exchanger modules  11 . The supply air channel  21  is separated from the exhaust air channel  20 . In the illustrative embodiment shown in  FIG. 1 , both the exhaust air channel  20  and the supply air channel  21  form an isosceles triangle, wherein the hypotenuse  22  rests on the ends  16  of the heat exchanger modules  11 , one side  23  is closed and one side  23  is open. 
         [0046]    The arrow  24  shown on the exhaust air channel  20  describes the direction in which the air flows into the exhaust air channel  20  and thus into all the inlets  17  of the heat exchanger modules  11 . The arrow  25  shown on the supply air channel  21  describes the direction from which air flows out of the outlets  18  of all the heat exchanger modules  11  through the supply air channel  21 . At the opposite end  16  of the heat exchanger modules  11 , an outgoing air channel and an exterior air channel are associated with the heat exchanger modules  11  in the same way. There, an arrow  26  indicates the inflow direction of the air into the supply air channel  21  and thus into the inlets  17  of the heat exchanger modules  11 . 
         [0047]    The apparatus illustrated in  FIG. 1  can be assembled from any number of identical heat exchanger modules  11  stacked one above the other. Moreover, the apparatus in the form illustrated in  FIG. 1  can also be operated side-by-side in the case of a multiple embodiment. 
         [0048]    In the illustrative embodiment of the apparatus  10  shown in  FIG. 1 , each heat exchanger module  11  has a length of 650 mm, a height of 180 mm and a width of 600 mm. The overall height of the apparatus  10  is thus the sum of the heights of all the heat exchanger modules  11  and of the modular wetting water reservoir  27  corresponding in dimensions to a heat exchanger module  11 . 
         [0049]    In  FIG. 2 , the apparatus  10  according to the invention is illustrated without the exhaust air channels  20  and the supply air channels  21 .  FIG. 2  shows the wetting water reservoir  27 , three heat exchanger modules  11 , which are stacked one above the other on the wetting water reservoir  27 , and one further heat exchanger module  11 , which is placed on the already assembled heat exchanger modules  11  as indicated by the arrow  28 . 
         [0050]    Each heat exchanger module  11  has a housing  13 , which in each case has an inlet  17  and an outlet  18  at each of the ends  16 . In the interior of each heat exchanger module  11  there is the single heat exchanger  29 . The heat exchanger  29  essentially comprises a multiplicity of upright heat exchanger plates  30  aligned parallel to one another and spaced apart. The heat exchanger plates  30  are aligned in such a way that they are perpendicular to the inlets  17  and outlets  18 . 
         [0051]    Each housing  13  of the heat exchanger module  13  has two opposite side walls  14 . These side walls  14  have depressions  31  and projections  33  at the lower edge  32  thereof. The corresponding upper edge  34  of a side wall  14  likewise has depressions  31  and projections  33 , corresponding to the projections  33  and depressions  31  on the lower edge  32 . When individual heat exchanger modules  11  are stacked one above the other, the projections  33  and depressions  31  on an upper edge  34  of both opposite side walls  14  engage in the corresponding projections  33  and depressions  31  on a lower edge  32  of two opposite side walls  14  of a subsequent heat exchanger module  11 . By means of the interengagement of the depressions  31  with the projections  33  of two successive housings  13  of the heat exchanger modules  11 , positive and accurately fitting assembly of successive heat exchanger modules  11  is achieved. 
         [0052]    The two housing halves  41  and  47  of each housing  13  are assembled together congruently and in a centered manner at the mutually facing end faces thereof and are connected together. Suitable centering means (not shown) hold the housing halves  41  and  47  of each housing  13  in the centered position thereof one above the other. 
         [0053]    The two opposite side walls  14  of each housing  13  of the heat exchanger modules  11  and of the wetting water reservoir  27  each have a segment of a wastewater channel segment  35 . By stacking the individual heat exchanger modules  11  one above the other, the individual wastewater channel segments  35  are assembled together in such a way that a continuous wastewater channel resembling a downpipe is formed, connecting all the heat exchanger modules  11  and the wetting water reservoir  27  to one another. Two successive wastewater channel segments in each case are joined together by means of a sealing ring  36  in such a way that no water can accidentally leave the wastewater channel. 
         [0054]    Each heat exchanger module  11  and the wetting water reservoir  27  furthermore have a pipe segment  37  on one of the side walls  14  thereof. The individual pipe segments  37  of each heat exchanger module  11  and the wetting water reservoir  27  are assembled together when stacked to form a pipe. To seal the individual pipe segments  37  with respect to one another, a sealing ring  38  is inserted between two pipe segments  37  as the individual pipe segments  37  are joined together. 
         [0055]    The wetting water reservoir  27 , on which the individual heat exchanger modules  11  are stacked, is used as the lower base of the apparatus  10 . The housing  13  or side walls  14  of the wetting water reservoir  27  has/have the same depressions  31  and the same projections  33  on the upper edges  34  thereof as the heat exchanger modules  11 . A positive and accurately fitting joint between the wetting water reservoir  27  and the lowermost heat exchanger module  11  is thereby produced. A positive joint of this kind between the individual heat exchanger modules  11  and between the heat exchanger modules  11  and the wetting water reservoir  27  prevents unwanted slipping of the individual heat exchanger modules  11  and the wetting water reservoir  27  relative to one another. 
         [0056]    At one end  16 , the wetting water reservoir  27  in the illustrative embodiment shown has a pump  39 . By means of this pump  39 , water is pumped out of the wetting water reservoir  27  into the heat exchanger modules  11  in a uniform manner through the individual pipe segments  37  of each heat exchanger module  11 . In these modules, the water is used to wet the heat exchanger plates  30 . Used cooling water or water which has dripped or run down the heat exchanger plates  30  is collected by collecting trays  40  integrated into the housings  13 . These collecting trays  40  of each heat exchanger module  11  are in contact with the wastewater channel segments  35  of each heat exchanger module  11 . The water collected in the collecting trays  40  flows through the individual wastewater channel segments  35  back into the wetting water reservoir  27 , where it is collected and is then fed to the individual heat exchanger modules  11  again through the pipe segments  37  by means of the pumps  39  in order to wet the heat exchanger plates  30 . 
         [0057]    In  FIGS. 3 and 4 , the principle of indirect evaporative cooling is illustrated by means of an illustrative embodiment of a heat exchanger module  11  and by means of arrows, which are intended to symbolize the air flow. In  FIG. 3 , a lower half  41  of the heat exchanger module  11  is illustrated with a plan view of the heat exchanger plates  30 . The lower half  41  of the heat exchanger module  11  has an inlet  17  and an outlet  18 . Exterior air  42  (indicated here by a triple arrow) flows into the housing  13  through the inlet  17  of the heat exchanger module  11  and subsequently flows through the interspaces  43  between the heat exchanger plates  30 . While the exterior air  42 , in particular fresh air, is flowing through the interspaces  43  of the heat exchanger plates  33 , the exterior air  42  is cooled. The exterior air  42  emerges from the outlet  18  of the heat exchanger module  11  as cooled supply air  44  on the opposite side of the heat exchanger plates. 
         [0058]      FIG. 4  shows the same lower half  41  of a heat exchanger module  11  as that in  FIG. 3 . Here, however, exhaust air  45  (indicated by a triple arrow) flows into the interior of the housing  13  through the opposite inlet  17 . The exhaust air  45  flows through the interspaces  43  between the heat exchanger plates  30 . However, the exhaust air  45  flows through the humidified interspaces  43  between the heat exchanger plates  30 . Owing to the air flow through the heat exchanger plates  30 , there is intensified evaporation of the water on the wetted heat exchanger plates  30 . By virtue of the evaporation process, the wetted heat exchanger plates  30  are cooled. The exhaust air  45  emerges from the heat exchanger  29  as moist outgoing air  46  through the outlet  18  of the heat exchanger module  11 . 
         [0059]    The cross-counterflow heat exchanger under consideration is configured in such a way that the exhaust air  45  or the outgoing air  46  does not come into contact with the exterior air  42  or the supply air  44 . The channels (not shown) in the interior of the heat exchanger  29  are mounted in such a way that the exhaust air  45  flows through the interspaces between corresponding adjacent heat exchanger plates  30 , absorbs moisture in the process and thereby cools the heat exchanger plates, and leaves the heat exchanger  29  again as outgoing air  46 . While the exterior air  42  passes through an unwetted cooled channel, releases heat or is cooled as it does so, and leaves the heat exchanger  29  again as cooled supply air  44 . 
         [0060]      FIG. 5  shows a heat exchanger module  11 , wherein the lower housing half  41  has not yet been joined together with an upper housing half  47  of the housing  13 . The lower housing half  41  and the upper housing half  47  of the housing  13  are designed in such a way that, in the assembled state, the two housing halves  41  and  47  form an inlet  17  and an outlet  18  at each of the ends  16  which are then formed. The upper housing half  47  is placed on the lower housing half  41  and connected thereto. On its upper side  12 , the upper housing half  47  has depressions  48  and raised portions  49 . These depressions  48  and raised portions  49  of the upper housing half  47  fit into corresponding depressions  48  and raised portions  49  of the underside  50  of the subsequent heat exchanger module  11  when the heat exchanger modules  11  are stacked together. In this way, it is ensured that the heat exchanger modules  11  stacked one above the other do not slip relative to one another. 
         [0061]    As already described above, the lower housing half  41  has depressions  31  and projections  33  on the side walls  14 , and these engage with the depressions  31  and projections  33  on the side walls  14  of the upper housing half  47  when the individual heat exchanger modules  11  are stacked one above the other. 
         [0062]    A lance  51  extends at right angles into the housing  13  from the pipe segment  37 . The lance  51  extends parallel to the heat exchanger  29  and perpendicularly to the heat exchanger plates  30 . The lance  51  has holes  52  at uniform intervals. Water jets  53  can emerge through the holes  52 , fed by the pipe segments  37  and the lance  51 . 
         [0063]    The number of holes  52  in the lance  51  is variable and can be chosen to match the number of heat exchanger plates  30 . The diameter of the holes  52  should be chosen in such a way that a directional water jet  53  is produced, even at a low water pressure. 
         [0064]    An opening  54  is provided at the upper edge  54  of the side wall  14  of the upper half  47  of the housing  13 . When the lower housing halves  41  and upper housing halves  47  are assembled together, the lance  51  extends through this opening  54  into the heat exchanger module  11 . 
         [0065]    In the lower half  41  in  FIG. 5 , arrows  55  indicate the course of the excess water from the heat exchanger  29  into the respective collecting tray  40 , from where it passes through outflows  56  into the wastewater channel  35 . This wastewater channel  35  carries the wastewater back into the wetting water reservoir  27 . 
         [0066]      FIG. 5  shows the separating wall  19 , which separates the lower half  41  from the upper half  47  of the housing  13  and separates the inlet  17  from the outlet  18 . It serves to ensure that exterior air  42  is not mixed with outgoing air  46  and supply air  44  is not mixed with exhaust air  45 . 
         [0067]      FIG. 6  shows a cut-away heat exchanger module  11 , looking toward the device for wetting the heat exchanger plates  30 . A water jet  53  emerges from each hole  52  of the lance  51  transversely to the heat exchanger plates  30 . All the water jets  53  are directed at a baffle surface  57 . This baffle surface  57  can be either the inner side of a depression  48  in the housing  13  or a strip introduced in addition as a baffle surface  57 . The baffle surface  57  is set obliquely to the water jets  53  and the heat exchanger plates  30 . This oblique angle is such that the water jets  53  impinge upon the baffle surface  57  at an angle which is unequal to  90  degrees, preferably  20  degrees to  80  degrees, in particular  40  degrees to  50  degrees. The baffle surface  57  extends obliquely to the perpendicularly oriented heat exchanger plates  30 . A wetting curtain  58  produced by the impact of the water jets  53  on the baffle surface  57  is thereby directed at the heat exchanger plates  30 , preferably in such a way that the wetting curtain  58  is oriented perpendicularly to the heat exchanger plates  30 . The water of the wetting curtain  58  is in the form of very fine droplets and settles on the preferably hydrophilic surfaces of the heat exchanger plates  30 . The droplets of the wetting curtain  58  which do not adhere to the heat exchanger plates  30  are collected by the collecting tray  40  and fed back to the wetting water reservoir  27 . 
         [0068]    A device of this kind for wetting the heat exchanger plates  30 , consisting of a lance  51 , can wet either just one side of the heat exchanger plates  30  or both opposite sides of the heat exchanger plates  30 . 
         [0069]      FIG. 7  shows a partial section through the wetting water reservoir  27 . The wetting water reservoir  27  likewise has a wastewater channel segment  35  on each of two opposite side walls  14 . These two wastewater channel segments  35  are connected to one another by a vertical channel  59 , which extends into the wetting water reservoir  27 . The vertical channel  59  is connected to the pump  39  by two outflow pipes  60 . Extending from the pump  30  through the interior of the wetting water reservoir  27  there is in turn an inflow pipe  61 , which is connected to the pipe segment  37  of the lowermost heat exchanger module  11 . This system comprising wastewater channel segments  35 , vertical channel  59 , pump  39 , inflow pipe  61 , pipe segments  37  and lance  51  forms a water circuit which feeds the wetting water to the heat exchanger plates  30  and collects excess water by means of the collecting trays  40 , which water is collected by the wetting water reservoir  27  and fed back to the heat exchanger plates  30 . 
         [0070]    The wetting water reservoir  27  can also be used as a large reservoir for water particularly wetting water. Water can be added to the wetting water reservoir  27  when required by means of liquid level sensors (not shown), which measure the wetting water level in the wetting water reservoir  27 . This ensures that there is always sufficient water in the circuit to wet the heat exchanger plates  30 . 
         [0071]    The apparatus described above is also suitable for heat recovery. The heat recovery does not have to operate according to the principle of evaporative cooling. In that case, wetting of the heat exchangers  29  can be omitted. Accordingly, an apparatus for heat recovery does not have to have any wetting water reservoir  27  or any components for wetting, in particular any water lines. 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           10  apparatus 
           11  heat exchanger modules 
           12  upper side 
           13  housing 
           14  side wall 
           15  surfaces 
           16  end 
           17  inlet 
           18  outlet 
           19  separating plate 
           20  exhaust air channel 
           21  supply air channel 
           22  hypotenuse 
           23  side 
           24  arrow 
           25  arrow 
           26  arrow 
           27  wetting water reservoir 
           28  arrow 
           29  heat exchanger 
           30  heat exchanger plate 
           31  depression 
           32  lower edge 
           33  projection 
           34  upper edge 
           35  wastewater channel segment 
           36  sealing ring 
           37  pipe segment 
           38  sealing ring 
           39  pump 
           40  collecting tray 
           41  lower housing half 
           42  exterior air 
           43  interspace 
           44  supply air 
           45  exhaust air 
           46  outgoing air 
           47  upper housing half 
           48  depressions 
           49  raised portions 
           50  underside 
           51  lance 
           52  hole 
           53  water jet 
           54  opening 
           55  arrow 
           56  outflow 
           57  baffle surface 
           58  wetting curtain 
           59  vertical channel 
           60  outflow pipe 
           61  inflow pipe PATENT