Patent Application
20150021001
1. Technical Field
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.
2. Prior Art
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.
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.
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.
Counterflow heat exchangers up to an air volume flow of 1500 m3/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 m3/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.
Counterflow heat exchangers of the type mentioned, which are suitable for air volume flows of 1500 m3/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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
A preferred illustrative embodiment of the invention is explained in greater detail below by means of the drawing. In this drawing:
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.
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 (
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.
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
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
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.
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.
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.
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
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.
The apparatus illustrated in
In the illustrative embodiment of the apparatus 10 shown in
In
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.
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.
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.
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.
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.
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.
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.
In
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.
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.
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.
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.
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.
In the lower half 41 in
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.
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 003 068.1 | Feb 2012 | DE | national |
| 10 2012 004 900.5 | Mar 2012 | DE | national |
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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/000403 | 2/12/2013 | WO | 00 |
