TECHNICAL FIELD

The present invention relates to a cleaning apparatus for cleaning a finned type heat exchanger, comprising a distributing device for distributing and applying cleaning medium on the side surfaces of the fins, and a method for cleaning a finned type heat exchanger, comprising applying a cleaning medium on the side surfaces of the fins by means of a distributing device according to the invention.

STATE OF THE ART

It is commonly known that heat exchangers in different applications such as in air- conditioners, ventilation systems, refrigerators and freezers, are clogged by dirt and grease, which results in that the efficiency gradually declines and the compressor has to work harder. For example, in a grocery store with a large number of refrigerator and freezer display cases, this results in enormous refrigeration/freezing costs. When a heat exchanger is clogged by dirt etc., bacteria thrive, which is not preferable, especially not in connection with food products. Cooling batteries are frequently mounted in inaccessible positions in the bottom or the back wall of a refrigerator/freezer display case. It is sometimes possible to get access to the actual cooling/heating battery, however only after removal of the surrounding parts, but the cleaning will still be awkward. Large resources are required for the cleaning of heat exchangers, which many times results in it being omitted. At the same, the fins in a heat exchanger are in most cases thin and easily damaged, which makes cleaning without damaging the fins difficult. The cleaning has usually consisted in vacuum cleaning removal of visible dust on the outside of the cooling battery, while attempts to clean the internal parts of the cooling battery have usually been made by means of pressurized air or high pressure rinsing with water. The last-mentioned methods are unsuitable. A high pressure cleaner will bend the fragile fins and destroy the heat exchanger. Furthermore, a large quantity of water is consumed and has to be recovered. There are some patented methods for the cleaning of heat exchangers.

A method of cleaning a heating, alternatively cooling battery in a heating or cooling apparatus is disclosed in document GB 2225828 A. After making the heating/cooling battery accessible, it is cleaned by means of a (wet) vacuum cleaner, detergent, and a combination of a water unit and an air compressor. A cleaning apparatus and a cleaning method for the heat exchanger in an air conditioner are disclosed in document US 5509972. A cover is fitted over a portion of the front side of the heat exchanger so as to serve as a splash shield when detergent followed by water are sprayed into the area covered by the cover.

BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention to eliminate, or at least minimize the above- mentioned problems, which is achieved in that a distributing device according to the invention is disposed transversely to the extension of the side surfaces of the fins, wherein an outlet side of the distributing device comprises a number of metering openings, adapted to the spacing of the fins, wherein at least one metering opening is disposed between two successive fins. Thanks to the invention, a cleaning apparatus/method, which enables cleaning of a heat exchanger in situ without damaging the fins and with a considerably smaller quantity of water than the current cleaning methods, is provided.

According to a further aspect of the invention, the distributing device extends transversely to the extension of the side surfaces of the fins, and a number of metering openings, adapted to the spacing of the fins, are present on an outlet side of the distributing device, wherein at least one metering opening is disposed between two successive fins, which results in a better distribution of the cleaning medium across the cooling battery.

According to a further aspect, at least one metering opening is disposed between each of the fins, whereby cleaning medium is applied between all fins.

According to another aspect of the invention, the distributing device comprises a space having an inlet for the cleaning medium and a plurality of outlets comprising said metering openings, wherein said outlets are smaller in area than the inlet, whereby a uniform distribution of the cleaning medium can be achieved. Since the distributing device has an elongated shape and the metering openings are disposed such that the spray characteristic of the metering openings distributes the cleaning medium along the longitudinal extension of the heat exchanger, preferably along the entire length, and preferably also along the entire width of the heat exchanger, an efficient cleaning can be provided without requiring any manual action during the cleaning process.

According to a further aspect of the invention, said distributing device is at least upwardly, but preferably also laterally surrounded by a cover, wherein said cover preferably comprises a planar top portion, and preferably also downwardly directed edge portions, which are preferably adapted to surround the outer edge portions of the heat exchanger, which assists in directing/forcing the cleaning medium down between the fins and prevents splashes in other directions than downwards. In addition, the cover contributes to making it easy to place the cleaning apparatus on the heat exchanger, since the cover encloses the heat exchanger to a certain extent and thereby holds it in place.

According to another aspect of the invention, the distributing device comprises a distribution box, which is preferably flat for the purpose of minimizing the quantity of cleaning medium therein. Alternatively, the distributing device comprises at least one elongated pipe having a small diameter.

For the purpose of enabling cleaning of heat exchangers of greater depth, said elongated pipe is adapted to form pipe sections disposed substantially in parallel and fluidically connected to one another via a transverse connecting pipe comprising a connector for the connection of a feed device for said cleaning medium, alternatively constitutes a continuous pipe coil, wherein said connector is disposed at one end of the pipe coil. According to another aspect of the invention, it is advantageous if the cleaning apparatus can be used for heat exchangers of different sizes, which is achieved in that the metering openings can be disposed within an angle on the outlet side of the pipe, and that the metering openings can be disposed in different ways, e.g. linearly or alternately about a central axis on the outlet side of the pipe.

By using a cleaning apparatus according to the invention, a method for cleaning of a finned type heat exchanger, comprising applying said cleaning medium on the side surfaces of the fins, can be provided. According to one aspect of the invention, the method comprises the step of disposing said distributing device transversely to the extension of the side surfaces of the fins, and initiating a cleaning sequence comprising uniformly distributing said cleaning medium on the side surfaces of the fins, whereby a uniform distribution of the cleaning medium is obtained. Since the cleaning sequence comprises applying steam, preferably dry, superheated steam having a temperature (Ts) of no more than 180°C and a pressure of 2 - 20 bars, more preferably 8 - 12 bars, for a duration (t) adapted to the total area of the side surfaces of the fins such that a temperature (T) of at least 85 °C is reached on the side surfaces (Y) of the fins, an efficient cleaning and a bactericidal effect are obtained. Furthermore, the advantage is achieved that the quantity of water used will be small and that steam easily fills up the space between the fins and reaches all surfaces in a delicate manner, and thereby reduces the risk of damaging the fins.

Since the cleaning sequence also comprises the step of applying water (W), preferably hot water having a temperature (T _w ) of 70 - 120°C, for a duration adapted to the total area of the side surfaces of the fins such that a temperature of at least 65°C is reached on the side surfaces of the fins and/or of applying cleaning chemicals, an efficient dissolution and removal of dirt from the side surfaces of the fins is obtained.

Since the cleaning medium is deionized, the risk of it conducting electricity is eliminated or at least minimized. BRIEF DESCRIPTION OF THE FIGURES

In the following, the invention will be described in more detail with reference to the attached figures of the drawings, in which:

Fig. 1 shows a lateral cross-section of a refrigerator display case with a cooling battery;

Fig. 2 shows a perspective view of a cooling battery;

Fig. 3 shows a cooling battery in a front view and a cleaning apparatus according to the invention;

Fig. 4 shows a cleaning apparatus according to the invention;

Fig. 5 shows a perspective view of a nozzle according to the invention;

Fig. 6 shows a nozzle according to the invention seen from below;

Fig. 7 shows a nozzle according to the invention seen from below;

Fig. 8 shows the cleaning of a cooling battery, in situ, according to the invention;

Fig. 9 shows an alternative distributing device according to the invention;

Fig. 10 shows a portion of a distributing device according to the invention;

Fig. 11 shows a cross-section of a bottom portion of a distributing device

according to the invention; Fig. 12 shows a perspective view of a cooling battery with holes for a cleaning apparatus according to the invention;

Fig. 13 shows a cooling battery with alternative holes for a cleaning apparatus according to the invention; and

Fig. 14 shows a perspective view of a cooling battery according to the invention.

DETAILED DESCRIPTION OF THE FIGURES

In the description of the invention, the heat exchanger will be described as a cooling battery 2 in a refrigerator/freezer display case, but the skilled person will appreciate that the invention is applicable to all forms of heat exchangers, such as in air-conditioning and ventilation installations.

As mentioned by way of introduction, the cleaning of cooling batteries constitutes a problem, since they are often mounted in inaccessible positions in the bottom or back wall of a refrigerator/freezer display case, in the space formed between an inside wall and an outside wall, where, among other things, insulating material is placed. In those few cases when they are located in a more easily accessible position, cleaning still remains a rare event, since it is difficult and awkward to clean them. In the example below, the invention will be described with reference to a vertical refrigerator display case, but the skilled person will appreciate that the example also applies to a horizontal refrigerator display case, with the difference that the shelves 4 shown in Figure 1 then will constitute vertical partition walls delimiting compartments for different food products. In the following, a cleaning apparatus and a method for simple and quick cleaning of a cooling battery 2 in situ, i.e. while the cooling battery 2 is mounted in a

refrigerator/freezer display case of the kind shown in Figure 1, by means of said cleaning apparatus, will be described. The use of the cleaning apparatus according to the invention when cleaning cooling batteries 2 in other embodiments of refrigerator/freezer display cases than the one described here, such as refrigerated/freezing gondolas, is also included within the scope of the invention. It should also be understood that the cooling batteries 2 can have other proportions than those described herein, e.g. be longer, higher, thinner, thicker, etc. Figure 1 is a schematic representation of a vertical refrigerator display case 1 seen from the side, wherein the cooling battery 2 is placed in the back wall of the refrigerator display case. The refrigerator display case 1 has an opening A, where customers can pick products from shelves 4 inside the storage space of the refrigerator display case 1. The refrigerator display case 1 comprises a fan 3, which in this refrigerator display case 1 variant is placed in the lower part of the refrigerator display case 1. The fan 3 brings air from the lower part of the storage space (in the direction of arrow B) of the refrigerator display case 1 towards a heat exchanger 2, in this case a cooling battery 2, through the cooling battery 2, and further upwards and out into the upper portion of the storage space (see arrows C, D and E) of the refrigerator display case 1.

Figure 2 shows a perspective view of a conventional cooling battery 2, said battery 2 comprising fins 20 disposed in parallel and a pipe coil 21 for the refrigerant.

Through the invention, a method for cleaning a cooling battery 2 is provided, wherein the fact that the cooling battery 2 is surrounded by the inside wall and outside wall of the refrigerator/freezer display case, which until now has been regarded as a

complicating factor for the access to the cooling battery, is used instead together with a cleaning apparatus according to the invention to thereby achieve conditions favourable for the purpose, and thereby enable an efficient cleaning of the cooling battery 2. More specifically, the inside wall and outside wall, respectively, of the refrigerator/freezer display case surround the cooling battery along the sides towards which the edges of the fins are facing. Thus, the inside and outside wall of the refrigerator/freezer display case interact with the side surfaces of the fins so as to create confined spaces, resembling a duct/conduit/passage, between the fins. These confined spaces contribute to enabling the cleaning medium to be distributed more uniformly between the fins in the cooling battery and on the side surfaces thereof in an efficient way.

The applicant has developed a nozzle 7, said nozzle 7 being shown in a perspective view from above in Figure 5. The nozzle 7 is designed for distributing and controlling the flow/distribution of the cleaning media through the cooling battery. The cleaning media include fluids such as chemical detergents (D), water (W) and steam (S). The nozzle 7 is adapted to be connected via a connector 71 to a machine (not shown) feeding the nozzle 7 with the required cleaning media (steam, water, detergents, etc.) at different pressures and temperatures. An example of a machine suitable for the purpose is provided by the company TECNOVAP Scandinavia AB (www.tecnovap.se) and has the designation Steam Pressure.

In a preferred embodiment, the nozzle 7 comprises a cover, suitably consisting of a substantially planar, rectangular top portion 70 having edge portions 74, 75, 76, 77, said edge portions extending substantially perpendicularly downward from said top portion 70. The edge portions comprise two long edge portions 74, 75 extending downwardly from the long sides of the top portion 70, and two short edge portions 76, 77 extending downwardly from the short sides of the top portion 70. Said long edge portions 74, 75 and short edge portions 76, 77 preferably have the same height, so that the lower edge of said long edge portions 74, 75 and short edge portions 76, 77 terminate in a common plane. This provides the advantage that, when the nozzle 7 is placed on top of the cooling battery 2 during cleaning, a closed space is provided between the cover of the nozzle, the outside and inside wall of the refrigerator/freezer display case enclosing the cooling battery 2, and the side surfaces of the outermost fins, which forms a

duct/conduit/passage so that the cleaning media can be distributed more uniformly between the fins in the cooling battery 2. The cover is preferably made of composite plastic, which is durable, easy to keep clean, and enables a simple manufacture, e.g. by compression moulding, but it is appreciated that other materials can be used, such as bent sheet metal, and that other manufacturing methods can be used without taking away from the purpose of the invention. The cover can be provided with handles, which may be thermally insulated, for the purpose of facilitating the handling of the nozzle 7. The connector 71 is preferably disposed centrally on the top portion 70 and is adapted to be connected to a distributing device 720, disposed on the bottom side of the nozzle 7, via a sealed through-hole (not shown) in the top portion 70.

Figure 6 shows a first embodiment of a nozzle 7 in a view from below. In this first embodiment, the distributing device 720 in its most simple form comprises an elongated, longitudinal pipe 72 with a number of metering openings 73, 73. Preferably, the metering openings 73 comprise metering holes 73 which are arranged along a central line, preferably uniformly distributed along the pipe and directed straight downward. Preferably, the metering openings 73 are positioned such in relation to the spacing of the fins that at least one metering opening 73 is disposed between two successive fins. Preferably, there is at least one metering opening between each of the fins. The distributing device 720 is connected (not shown) to the connector 71 on the top side of the nozzle via a sealed hole (not shown) in the top portion 70, in order to be supplied with water, steam, etc. from the machine therethrough. The distributing device 720 preferably extends centrally in the longitudinal direction of the nozzle 7 and extends between the two short side portions 76, 77 of the nozzle.

The metering holes 73 are adapted to apply a uniform flow and a uniform distribution of the fluids (detergents, steam, water) through the cooling battery and thereby ensure that all parts will be cleaned. The number of metering holes and their size can be varied as needed. For the purpose of providing a flow of cleaning medium which is sufficient to rinse away accumulated dirt on the side surfaces of the fins, but at the same time minimizing the quantity of fluid consumed, a version with fewer metering holes having a small diameter is preferred as compared to a version with fewer metering holes having a larger diameter. Suitably, the metering holes 73 have a diameter of 0.2 - 1.5 mm, preferably 0.5 - 1.0 mm, most preferably 0.6 - 0.8 mm, typically 0.7 mm, and have a spacing of 2- 20 mm, preferably 2 - 15 mm, most preferably 2 - 10 mm. In the shown embodiment, the metering holes 74 are circular with a diameter of 0.70 mm. The metering holes 73 are arranged along a central line and directed straight downward with a spacing of 10 mm. The length of the pipe 72 is about 625 mm, which corresponds to a common standard size for a cooling battery. Cooling batteries in larger sizes are often multiples of this standard size, i.e. 1250 mm, 1875 mm, and so on.

Another alternative can be that the pipe 72 is provided with one or several longitudinal slits so that the fluids are applied in a fan-shape (not shown). Transverse slits 73' are also conceivable, see Figure 9 where a section of a pipe 72 is seen from the side. It is common to both holes and slits that their shape can be varied for the purpose of obtaining the desired spray characteristic of the fluids, for the purpose of obtaining the best possible cleaning effect, e.g. be straight, convergent or divergent, see the examples of different shapes of the holes in Figure 10, where several holes are shown side by side, more for reasons of simplicity than for the purpose of illustrating an actual embodiment, even if combinations of straight, convergent and divergent holes or slits are conceivable in the same pipe 72, as well as a combination of several pipes 72 with mutually different shapes of the metering holes.

It can also be advantageous that the distributing device 720 applies the fluid upwardly toward the top portion 70, by means of which the fluid flowing upward is surrounded by the top portion 70 and the edge portions 74, 75, 76, 77, and is thereby uniformly distributed therein, to then be forced downward towards the cooling battery 2 and in between the fins 20.

An alternative embodiment of a distributing device 720 according to the invention is seen in Figure 7. Here, the distributing device 720 comprises a first 72A and a second 72B pipe extending in parallel between the short side portions 76, 77 of the nozzle. The two pipes 72A, 72B are fluidically connected to one another via a transverse connecting pipe 72C, said connecting pipe preferably being centrally disposed. Preferably, the connecting pipe 72C is centrally disposed adjacent to the through-hole and connected to the connector 71 on the top side 70 of the nozzle. Still another alternative embodiment comprises a continuous pipe coil in the shape of a U. In this alternative, the connector 71 is preferably disposed at one end of the coil (not shown). The skilled person will appreciate that also a longer continuous pipe coil laid out with several bends is encompassed by the inventive concept. The alternative embodiments above are particularly advantageous to use if it is a cooling battery of greater depth that is to be cleaned.

As mentioned previously, the nozzle 7 is connected to a machine feeding the nozzle with steam, water, etc. The functions which the nozzle 7 should be provided with from the machine can preferably be entered on a display device on the handle of the machine so that the different functions are preprogrammed and followed in a predetermined continuous cleaning process. It is of course also possible to decide from case to case which cleaning steps that are to be included and in which order they are to be executed. Accordingly, it is appreciated that the same nozzle 7 is used throughout all steps in the cleaning process, which saves time and work steps. Preferably, in order to be able to clean most types of cooling batteries, an assortment of nozzles 7 of different sizes suitable for the most common modules is provided. Cooling batteries are normally made in certain standard sizes, and in larger sizes the dimensions are often multiples of the smallest module and therefore the same nozzle can be used for section-wise cleaning. Another alternative embodiment of the distributing device 720 could be such that the distributing device 720, as in Figure 7, comprises a first 72A and a second 72B pipe extending in parallel with each other. The two pipes 72A, 72B are fluidically connected to one another via a transverse connecting pipe 72C. The difference compared to the distributing device 720 depicted in Figure 7 is that the two pipes 72A, 72B in this alternative embodiment are rotatably fitted to the transverse connecting pipe 72C, so that the metering openings 73 can be directed along the pipe within an angle of (v) ± 60° from an imaginary line (L) through the central axis of the pipe which is parallel to, or substantially parallel to the extension of the side surfaces, preferably is v ± 30°, more preferably is v ± 15°. The advantage of having the pipes arranged like this is that the metering holes 73 are directed straight downward in an initial position. If one assumes that a standard cooling battery 2 has a depth of 130 mm, the length of the connecting pipe is preferably 30 mm, so that the two pipes 72A, 72B end up about 40 mm inward from the two sides of the cooling battery. The metering holes 73 are directed straight downward between the fins 20, and when applying cleaning medium, the medium is uniformly distributed across the cooling battery 2. If a cooling battery 2 of greater depth is to be cleaned, for example one having a depth of 140 mm, the two pipes are rotated by an angle v so that the metering holes 73 are directed toward each side of the battery, that is to say one pipe 72A, 72B is rotated clockwise, while the other one 72A, 72B is rotated counter clockwise. The cleaning medium will then flow more laterally, which results in a more uniform distribution across a deeper cooling battery 2 than if the metering holes 73 were to be directed straight downward, since the cleaning medium would not reach all the way to the edges of the cooling battery 2 in that case. The metering holes 73 are disposed along the bottom side of the pipes 72A, 72B within an angle v from said line L. Owing to the fact that the two pipes 72A, 72B are rotatably disposed, one and the same distributing device 720 could clean cooling batteries 2 having a depth of from 100 mm up to a depth of 160 mm. The constituent parts of the distributing device 720 can of course be adapted in size to enable them to be used for cooling batteries 2 having both smaller and greater depths than the one described above. It is, of course, also conceivable to instead provide an assortment of distributing devices where the pipes 72A, 72B have been angularly disposed in a certain range already from the factory and fixedly mounted to the transverse connecting pipe 72C to reach the same purpose.

In the following, it will be described how a preferred cleaning sequence is carried out, but it should be understood that also other combinations of cleaning steps can be used without therefore departing from the inventive concept and that other cleaning media than the ones described here, other flow rates, pressures and temperatures can be used. Figure 8 shows how the shelves 4 in a refrigerator display case 1 have been removed and the cooling battery 2, in this described example, is mounted in the back wall of the refrigerator display case 1 between an inside wall 5 and an outside wall 6. When cleaning the cooling battery 2 is either the inside wall 5 or the outside wall 6 removed from an area over the cooling battery, which wall to remove depends on how the refrigerator display case 1 is placed, in this case the inside wall 5 is disassembled. After having removed the shelves 4 and the front plate 5 in the refrigerator display case 1, the distributing device is disposed transversely to the extension of the side surfaces of the fins of the exposed cooling battery 2, see Figures 3 and 8. An outlet side of the distributing device comprises a number of metering openings, adapted to the spacing of the fins, wherein at least one metering opening is disposed between two successive fins of the cooling battery 2. Normally, the fins 20 have a spacing of 2 - 20 mm. The distributing device 720 is preferably placed adjacent to the side of the cooling battery that constitutes an outlet side for the cooling air when the refrigerator/freezer is in operation. The reason for this is that dirt is accumulated on the inlet side for the cooling air, which means that dirt is removed more easily if the cleaning medium is applied counter-currently, as seen relative to the flow direction of the cooling air.

Figure 3 is a schematic representation of what it would look like seen straight from the front when the nozzle 7 is placed on top of an exposed cooling battery 2 (the walls are not drawn). The nozzle 7 is made in different sizes according to what has been described in the foregoing to be adaptable to the type of cooling battery 2 which is to be cleaned. The nozzle 7, in its turn, is connected via a connector 71 to a machine, for example Steam Pressure from TECNOVAP Scandinavia AB, which preferably on its handle 8 has a digital (alternatively manual) display device for setting different functions.

Accordingly, during cleaning, the nozzle 7 is placed on top of the cooling battery 2. It is conceivable that that the nozzle 7 is placed such that the distributing device 720 bears against the fins 20, alternatively that the distributing device 720 is placed a small distance above the fins, but it is most preferred that the distributing device is disposed 0.5 - 1 cm above the fins 2. Preferably, the nozzle 7 has a size adapted to the exposed portion of the cooling battery 2 such that when the nozzle 7 is placed over the cooling battery 2, the edge portions 74, 75, 76, 77 of the nozzle close in around the uppermost portion of the cooling battery 2, so that the nozzle 7 is held in place without any additional means. An alternative embodiment of the nozzle 7 could be a telescopic solution, where the nozzle 7 can be extended to the desired length in the longitudinal direction, which enables the same nozzle 7 to be used for a number of cooling batteries of different lengths. Thereupon, the desired cleaning cycle is selected via a display device on the machine and the cleaning can start. In a preferred cleaning cycle, the cleaning starts with the distributing device 720 applying a detergent D in the form of foam or spray between the fins, via the metering openings 73, 73'. The detergent preferably dissolves grease and has a pH value in the range of 4 - 9, since aluminium is sensitive to pH values outside this range. The skilled person will appreciate that if the cooling battery is made of another material than aluminium, the pH value can then be adapted to that material. The detergent is then left to act for a short time to dissolve dirt and grease. The duration will of course be determined by the degree of contamination and type of dirt and must be adapted thereto, but it is advantageous if the time consumption can be kept down. This step where detergent is applied and left to act on the cooling battery 2 has a maximum duration of 20 minutes, more preferably no more than 10 minutes, and most preferably the step has a maximum duration of 2 minutes. Examples of possible detergents are provided by the company Kylma ( www.kylma.se) under the product ranges CoolSafe ® refrigerator display case cleaner and EnviroCoil® evaporator cleaner.

As a second step, see Figure 4, dry, superheated steam from the metering openings 73, 73' in the distributing device 720 is forced down between the fins 20 and cleans and dissolves the dirt even more. Preferably, the steam is deionized and has a maximum temperature of 180 °C and a pressure in the range of 2 - 20 bars, more preferably in the range of 8 - 12 bars. The advantages of using dry steam are many, such as that the cleaning process leaves very small amounts of water. The cover of the nozzle 7 assists in forcing/directing the steam downward through the battery. This effect arises due to the fact than the nozzle forms like a cap on top of the battery and the steam thus has to flow downward through the battery to then be passed out through the lower end of the battery. The steam will also quickly and easily fill up the space between the fins 20 and reaches all nooks and corners, and does not damage the thin fins 20 like a high pressure cleaner might do. The high temperature of the steam does not only produce a visible result, but also ensures that the surfaces are disinfected and cleaned deeply.

Microorganisms such as bacteria, viruses, mites are eliminated efficiently. Another advantage of steam is that an efficient distribution can be achieved also in cases where the cooling battery is disposed in the bottom of a refrigerator/freezer display case, since the steam is not affected by gravity but fills up all nooks and corners in the cooling battery. Also the fact that the inside and outside wall of the refrigerator/freezer display case surrounds the cooling battery and forms a duct/conduit/passage in interaction with the side surfaces of the fins will contribute in this case.

Steam is applied until it has filled the spaces between the fins 20, preferably from the top portion to a lower level Nl adjacent to a portion opposite to the portion that the distributing device 720 is applied to, see Figure 4, and until the surface temperature on the fins 20 at the lower level Nl has reached a minimum temperature of 85 °C in order to ensure that all bacteria are killed. Preferably, the lower level Nl is at the lower edge of the fins, since the lower portion is the one with the highest degree of contamination with respect to both particles and bacteria, which is a natural consequence of a conventional way of setting up the air flow in a refrigerator/freezer display case. The step where steam is applied has a maximum duration of 20 minutes, more preferably no more than 10 minutes, and most preferably a maximum duration of 2 minutes, and the degree of superheating and the flow rate are adapted such that that the time can be kept down. When the nozzle 7 has been placed on top of the cooling battery 2 and forces the steam downward between the fins 20, the inside wall 5 and outside wall 6 of the refrigerator, see figure 8, serve as a kind of confinement, so that the steam does not just leak out to the sides, but really passes through all fins 20. Although there is a certain distance between the cooling battery 2 and the inside wall and the outside wall 6, and even though it is not completely sealed at the top where the distributing device 720 is disposed on the cooling battery 2, the space is confined enough to cause the major part of the steam to be forced to take the intended path through the fins 20.

The steam is followed by a rinsing step, see Figure 4, where preferably also the water is deionized, and preferably has a temperature in the range of 70 - 120 ° and a pressure in the range of 2 - 20 bars, more preferably no more than 10 bars, suitably in the range of 6 - 10 bars. The water is sprayed downward through the fins 20 to rinse away dirt, detergents, etc. The metering openings 73, 73' are preferably disposed such that they produce a uniformly distributed spray/shower of water across the side surfaces of the fins 20. Since the distributing device 720 produces a plurality of small water jets and the flow rate of each water jet is small, the fins are not damaged, in spite of the fact that a relatively high pressure is used. In some cases, the rinsing step can be omitted, since the steam condenses and provides a certain rinsing action on the fins. If steam with a lower degree of superheating is used, a larger quantity of condensed water and a greater rinsing action are obtained. Owing to this cleaning method, the fluid consumption is very small, a maximum consumption of water is 20 litres, more preferably a maximum consumption of 10 liters, and even more preferred is a maximum consumption of 1 liter of fluid, per cleaning sequence. A cleaning sequence then includes the three steps applying detergent, steam washing and rinsing. Then it is to be understood that one or several of the steps can be omitted, alternatively can be switched in order according to needs and desires. The quantity of water consumed in a cleaning sequence is to some extent also influenced by the size of the cooling battery 2 and the amount of dirt, and the above-mentioned consumption of fluid refers to a cooling battery of standard design as regards the ratio between length:depth:height, wherein the length amounts to a maximum of 1 m.

Additional advantages of the small quantities of steam and fluid in the cleaning method according to the invention is that the refrigerant in the pipe coil 21 has no time to be heated as much during a cleaning sequence. Since all pressurized systems today comprise safety valves that are triggered if, among other reasons, the refrigerant gets too hot, the triggering of the safety valves can be avoided by means of the cleaning method according to the invention. In the current methods of cleaning energy exchangers, air compressors, aerosols etc. are used, which means that bacteria and fungi are spread into the air, for example in a store. These methods require that the premises/store are/is closed, and sometimes also that the person performing the cleaning works in full protective suit to protect himself/herself. By means of the method according to the invention, energy exchangers can be cleaned without having to evacuate the premises where the energy exchanger is located, and the people working with the cleaning do not have to wear protective suits either, since the steam has a temperature which ensures that bacteria etc. are killed.

Excess water/condensed water flows downward through the cooling battery 2 and then follows the existing arrangement for the normal condensed water in the refrigerator display case 1 , which is usually arranged to pass to some kind of sewer/floor drain. The small amount of water used in the cleaning facilitates cleaning of cooling batteries 2 while the store is open, whereas otherwise there is a risk that water spills out on the floor. An alternative that is particularly advantageous when cleaning large cooling batteries 2, where the steam has to be forced a longer distance to reach all the way to the lower part of the cooling battery 2, can be to connect a wet vacuum cleaner 9 to the side of the cooling battery that is opposite to the side to which the distributing device 720 is applied. Thereby, the wet vacuum cleaner 9, on the one hand, produces suction from the opposite side, which makes it easier to get the steam to pass through all the way along the fins 20, and, on the other hand, the wet vacuum cleaner 9 directly collects the fluid used during the cleaning.

Yet another advantage of the cleaning method according to the invention is that a cleaning sequence according to the preferred embodiment, with the three cleaning steps detergent, steam and rinse, occupies a short time, of a maximum duration of 20 minutes, more preferably the cleaning sequence has a maximum duration of 10 minutes, and most preferably a maximum duration of 5 minutes. Thanks to the short duration of a cleaning cycle comprising all three steps, many refrigerator/freezer display cases can be cleaned in a short time. It should also be mentioned that the cleaning of the cooling batteries 2 takes place in situ and also can be done in day time when the stores are open, since there is no need for moving the refrigerator/freezer display cases. Also the small quantity of water used and the short cleaning time contribute to the fact that it is possible to perform the cleaning during the opening hours of a store. To further improve the situation for the store when the cleaning takes place during opening hours, it is possible to hang a curtain or the like in front of the open part of the refrigerator/freezer display case to prevent steam/condensation from spreading outside the actual refrigerator/freezer display case. It is also possible to place ice in a wet vacuum cleaner 9, if such a machine is used, wherein the ice causes the steam to condense inside the wet vacuum cleaner and it does pass directly through the machine and out into the room.

The problem with clogged, dirty cooling batteries results in a reduction of the effectiveness of refrigerator/freezer display cases, since the efficiency gradually declines at the same time as the compressor has to work more. This means than stores with many refrigerator/freezer display cases have enormous electricity costs, and they can, owing to the invention, reduce their energy consumption by 10 - 40 % of the share used for refrigeration/freezing. From a general point of view, it can be said that the share of refrigeration/freezing constitutes about 50 % of the total energy consumption in a grocery store. Considerable savings can be made for each meter of cooling battery and, accordingly, there are great cost savings to be made by regularly cleaning the cooling batteries in a refrigerator/freezer. According to the inventive concept, it is also possible that a distributing device 720 is fixedly mounted above a cooling battery for periodic cleaning, for example by being fastened by means of clips. In that case, it is advantageous to use a distributing device 720 without any cover, to not unnecessarily restrict the passage of the cooling air through the cooling battery and further through the conduits for distributing the cooled air of the refrigerator/freezer display case. In this case, the distributing device 720 is fixedly mounted above the cooling battery 2, in accordance with the principle of mounting it adjacent to the fins that has been described above, and connected to a machine, for example Steam Pressure as described previously. The cleaning of the cooling battery 2 can then be performed periodically to prevent the cooling battery from being clogged by dirt and grease, which causes the efficiency to gradually decline.

An alternative embodiment of a cleaning device according to the invention is depicted in Figs. 12-14. In order to facilitate the understanding, elements having the same or substantially the same function as those described previously are indicated with the same reference symbols. Common characterizing features and advantages that have already been described will not be repeated. Furthermore, it is appreciated that the alternative embodiments described in connection with Figs. 12-14 and the common characterizing features described previously may be the subject of dependent claims.

In Figs. 12-14, it is depicted how an energy exchanger can be provided with a cleaning device according to the invention during manufacture. From now on, the energy exchanger will be described as a cooling battery 2 for a refrigerator/freezer display case, but the skilled person will appreciate that the invention is applicable to all forms of energy exchangers. Furthermore, it is appreciated that the appearance of the cooling battery 2 during manufacture is described in connection with the figures, but that the outside and inside wall of the refrigerator/freezer display case and the side surfaces of the outermost fins serve as boundaries and form a drum/conduit/passage when the cooling battery 2 is disposed in a refrigerator/freezer display case, so that the cleaning media can be distributed more uniformly between the fins in the cooling battery 2 in accordance with the previous description.

Figure 12 shows a perspective view of a conventional cooling battery 2 comprising fins 20 disposed in parallel, a pipe coil 21 for the refrigerant, and an extra hole 200 in each fin 20. However, in the figure, only the hole 200 in the outermost fin 20A, at the extreme right of the figure, is visible. All fins 20 comprise at least one hole 200, said holes 200 being aligned with each other so as to be capable of receiving a distributing device 720 according to the invention. It is also possible that the fins 20 comprise two holes 200 next to each other, preferably in a horizontal direction, which is seen Figure 13, for receiving a distributing device 720 in the form of a continuous pipe coil in the form of a U. The skilled person will also appreciate that the fins 20 may comprise additional holes 200 if the cooling battery 2 is deeper and a distributing device 720 comprising a longer continuous pipe coil needs to be used. Preferably, the holes 200 are disposed as close as possible to the upper edge 20B of the fins to make it easier for the cleaning media to reach all nooks and corners of the fins 20. Figure 14 shows a perspective view of a cooling battery 2 according to the invention, said cooling battery comprising a distributing device 720. In this embodiment, the distributing device 720 comprises an elongated, longitudinal pipe 72, preferably fixedly arranged in said hole 200 in a manner known to the skilled person. One end of the distributing device comprises a connector 71 and the other end is closed, so that the cleaning media fill the pipe 72, and through metering openings 73, 73' it applies a uniform distribution and a uniform flow of the fluids through the cooling battery 2, in accordance with the previous description. The design and function of the distributing device 720 is described previously in the present application and have the same function here, with the difference that the distributing device 720 is disposed at the upper end of the cooling battery 2, preferably above the pipe coil 21 for the refrigerant. An advantage of arranging the cooling battery 2 with a distributing device 720 therein during manufacture is that a periodic cleaning of the cooling batteries 2 of refrigerator/freezer display cases can be carried out without first having to remove, for example, an outside/inside wall. Preferably, the distributing device 720 in the cooling battery 2 is connected to a machine suitable for the purpose, for example Steam Pressure described previously, and when it is time for cleaning the machine is started, and the desired functions are available. A possible variant is that a suitable machine is connected only during the actual cleaning session, and then via a connector 71, preferably a quick connector disposed at one end of the distributing device 720, see Figure 14.

Another variant of arranging a distributing device 720 in the cooling battery 2 during manufacture is to leave out one or several horizontal sections of the pipe coil 21 for the refrigerant, and to use these holes in the fins 20 for the distributing device 720. It is also appreciated that it is possible to provide the fins with extra holes in which a distributing device 720 according to the invention can be disposed in a retrofitting operation.

Alternatively one or several pipe coils for refrigerant in the cooling battery can be removed to thus provide space for mounting a distributing device therein. According to the inventive concept, it is also possible that a distributing device 720 is fixedly mounted above a cooling battery 2 during manufacture.

In the case when a distributing device 720 is arranged in a cooling battery 2 during manufacture and/or by retrofitting, it is advantageous to use a distributing device 720 without any cover, to not unnecessarily restrict the passage of the cooling air through the cooling battery and further through the conduits for distributing the cooled air of the refrigerator/freezer display case. If the advantages that can be offered by a cover are still desired, i.e. that it contributes to forcing/directing the steam downward through the fins, there is the possibility of placing a loose cap, screen, or something else confining the space, such as a piece of sheet metal, on top of the cooling battery 2, so that the major part of the steam is forced to take the intended path through the fins 20. It is of course also possible to fit some kind of cap/cover, during the manufacture, disposed on the cooling battery 2, or adjacent to the cooling battery 2 by means of hinges, so that it can easily be folded down during the cleaning session. It is of course appreciated that it is also possible that the cleaning process is carried out without any cap/cover, but that the pressure of the steam has to be raised to enable it to be forced down through the fins. It is also appreciated that it is possible to arrange one or several distributing devices 720 in a cooling battery. For example, in a very high battery, there can be two or more levels of distributing devices 720. In that case one can optionally choose to operate one or several of the distributing devices 720. Since the flow through the battery passes from the bottom upwards, more dirt is accumulated at the lower end, and with this embodiment one can then choose to clean the lower end more frequently than other parts/the whole battery.

The invention is not limited to what has been described above, but can be varied within the scope of the following claims. For instance, it is appreciated that detergents, steam, etc. can expelled from the nozzle 7 through passages, said passages being an integrated part of the top portion 70 of the actual nozzle. A conceivable embodiment comprises a flat distribution box, for the purpose of minimizing the quantity of cleaning medium therein, wherein a lower plate comprises said distributing openings. In spite of the fact that the described example deals with a cooling battery, the skilled person will also understand that the cleaning method is suitable for all forms of heat exchangers. It is also appreciated that the cleaning of a heat exchanger can be done from any side of the heat exchanger, entirely depending on how the heat exchanger is placed in its application, and where it is most easily accessible to the nozzle.