EP2742307B1

EP2742307B1 - Self cleaning heat exchanger device

Info

Publication number: EP2742307B1
Application number: EP11743055.3A
Authority: EP
Inventors: Christian SCHEUMANN
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2011-08-08
Filing date: 2011-08-08
Publication date: 2019-05-29
Anticipated expiration: 2031-08-08
Also published as: EP2742307A1; CN103797327B; CN103797327A; WO2013020579A1

Description

The present invention relates to a self cleaning heat exchanger device.
Refrigeration circuits circulating a refrigerant and comprising in the direction of the flow of the refrigerant a compressor, a heat rejecting heat exchanger, an expansion device and an evaporator are known for a long time, and they are used e.g. in refrigeration systems which are used for cooling refrigerated sales furnitures or in air conditioning systems.
The heat exchanger of such a refrigeration circuit is usually arranged outside a building in order to provide an effective heat exchange with the environment. As a result the heat exchanger gets polluted easily by dust, leaves and/or other items from the environment which obstruct or even block the air flow through the heat exchanger thereby deteriorating the efficiency of the heat exchanger. This increases the energy consumption and may even result in the breakdown of the refrigeration circuit. It is therefore necessary to periodically clean the heat exchanger in order to restore its full cooling capacity.
US 5,186,240 A discloses a coil cleaning assembly for automated cleaning of dirt and debris from within banks of heat exchanger coils. The cleaning assembly is mounted above, below and between banks of such coils to enable focused jets of high velocity spray to impinge upon the surfaces of the coils and, thus, dislodge particles. An alternative embodiment for the cleaning spray assembly includes a rotating arm system with spray ports mounted on a spray supply tube and a longitudinal track arrangement upon which a plurality of wand-type spray bars are mounted for reciprocating travel. US 2007/0125520 A1 discloses a refrigeration circuit according to the preamble of claim 1.
It would be beneficial to provide a self cleaning heat exchanger device which is easier to manufacture and to maintain and which allows a reliable cleaning of the whole surface of the heat exchanger. It furthermore would be beneficial to provide a method for automatically cleaning a heat exchanger device which is easy to implement at low costs and which allows to reliably clean the whole surface of the heat exchanger.
A self cleaning heat exchanger device according to exemplary embodiments of the invention is described in claim 1.
A method of cleaning a heat exchanger device according to exemplary embodiments of the invention is described in claim 14.
Exemplary embodiments of the invention will be described in detail below with reference to the enclosed figures, wherein:

Figure 1 shows a schematic side view of a self cleaning heat exchanger device according to a first embodiment of the invention;
Figure 2 shows a schematic top view of the heat exchanger device according to the first embodiment;
Figure 3 shows a schematic side view of a heat exchanger device according to a second embodiment of the invention; and
Figure 4 shows a schematic top view of the heat exchanger device according to the second embodiment.

The first embodiment of a self cleaning heat exchanger device 2a shown in Figure 1 comprises a heat exchanger 4, which extends basically horizontally and which is arranged on two supports 3 in a predetermined distance from the ground in order to allow air to flow vertically through the heat exchanger 4.
The air preferably flows upwards from the bottom to the top through the heat exchanger 4 so that the heat exchanger 4 comprises an air inlet side 5a at its bottom facing the ground and an opposing (upper) air outlet side 5b. The air enters the heat exchanger 4 at the air inlet side 5a and exits the heat exchanger 4 at the air outlet side 5b. At least one air temperature sensor 38, which is configured for sensing the temperature of the air entering the heat exchanger 4, is arranged at the air inlet side 5a of the heat exchanger 4.
The heat exchanger 4 further comprises a refrigerant inlet line 32 and a refrigerant outlet line 34 for flowing refrigerant into and out of the heat exchanger 4. A refrigerant temperature sensor 36 is arranged at the refrigerant outlet line 34 and configured for sensing the temperature of the refrigerant leaving the heat exchanger 4 through the refrigerant outlet line 34.
The refrigerant to be cooled by the heat exchanger 4 enters the heat exchanger 4 via the refrigerant inlet line 32 and flows through cooling coils or fins, which are not shown in Figure 1, of the heat exchanger 4 in order to transfer heat from the refrigerant to the air passing by the cooling coils or fins, respectively. The cooled refrigerant leaves the heat exchanger 4 via the refrigerant outlet line 34. The cooling operation of the heat exchanger 4 and the details of the coils or fins are known to the skilled person and are therefore not described in detail.
In order to enhance the flow of air through the heat exchanger 4 fans 6a, 6b, 6c are arranged above the heat exchanger 4 facing its air outlet side 5b. The fans 6a, 6b, 6c are configured to suck air from the air inlet side 5a to the air outlet side 5b through the heat exchanger 4. They can be activated and deactivated individually. The enhanced airflow passing the cooling coils or fins of the heat exchanger 4 improves its cooling capacity.
The exemplary embodiment of the heat exchanger device 2a shown in Figure 1 comprises three fans 6a, 6b, 6c, which are respectively associated to corresponding portions 4a, 4b, 4c of the heat exchanger 4 in a way that each of the fans 6a, 6b, 6c sucks air (only) through the respectively associated portion 4a, 4b, 4c of the heat exchanger 4.
The heat exchanger 4 may comprise internal valves, which are not shown in the Figures and which allow to selectively allow and block the flow of refrigerant through each of the portions 4a, 4b, 4c of the heat exchanger 4. In this case each of the portions 4a, 4b, 4c of the heat exchanger 4 may be deactivated individually by blocking the flow of refrigerant through the respective portion 4a, 4b, 4c.
In order to allow for an automatic cleaning of the heat exchanger 4 at least one cleaning fluid dispensing member 89 is arranged between the air outlet side 5b of the heat exchanger 4 and the fans 6a, 6b, 6c. In the embodiment shown in Figure 1 the cleaning fluid dispensing member 89 is formed as a pipe which extends horizontally basically parallel to the air outlet side 5b of the heat exchanger 4.
The cleaning fluid dispensing member 89 comprises a plurality of fluid dispensing openings 10 which are configured for dispensing cleaning fluid from the cleaning fluid dispensing member 89 to the air outlet side 5b of the heat exchanger 4.
The fluid dispensing member 89 is rotatable/pivotable around its longitudinal axis extending basically parallel to the air outlet side 5b of the heat exchanger 4 in order to allow to distribute the cleaning fluid over the whole surface of the air outlet side 5b of the heat exchanger 4.
When cleaning fluid is dispensed from the cleaning fluid dispensing member 89 to the air outlet side 5b of heat exchanger 4, it is beneficial when no airflow is present in the portion 4a, 4b, 4c of the heat exchanger 4 to be cleaned, since an upwardly oriented airflow through the heat exchanger 4 may prevent the cleaning fluid from flowing down through the heat exchanger 4.
On the other hand it is desirable not to deactivate the heat exchanger 4 completely for cleaning, as the operation of the refrigeration circuit would have to be stopped in this case, as well.
The cleaning fluid dispensing member 89 therefore is configured to allow to dispense the cleaning fluid selectively to one or more of the portions 4a, 4b, 4c of the heat exchanger 4. In this case, only the selected portion(s) 4a, 4b, 4c of the heat exchanger 4 and the corresponding fan(s) 6a, 6b, 6c has/have to be deactivated while the other portion(s) 4a, 4b, 4c of the heat exchanger 4 and the corresponding fan(s) 6a, 6b, 6c may continue to operate and the refrigeration circuit does not need to be stopped.
Figure 2 shows a schematic top view of the heat exchanger 4 having three portions 4a, 4b, 4c and a cleaning device comprising a plurality of cleaning fluid dispensing members 81 - 89 allowing to clean each of the portions 4a, 4b, 4c of the heat exchanger 4 individually. In the top view shown in Figure 2 the fans 6a, 6b, 6c, which are arranged on top of the cleaning fluid dispensing members 81 - 89, have been removed in order to give an unobstructed view onto the heat exchanger 4 and the cleaning device formed by the cleaning fluid dispensing members 81 - 89.
The cleaning fluid dispensing members 81 - 89 extend basically horizontally and parallel to each other over the air outlet side 5b of the heat exchanger 4 and respectively comprise a plurality of fluid dispensing openings 10 which are configured for dispensing cleaning fluid to the air outlet side 5b of the heat exchanger 4.
The cleaning fluid dispensing members 81 - 89 form three groups, wherein the fluid dispensing members 81 - 89 of each group are provided with fluid dispensing openings 10 for respectively dispensing cleaning fluid to (only) one of the portions 4a, 4b, 4c of the heat exchanger 4.
In particular, the cleaning fluid dispensing members 81, 82, 83 of the first group comprise fluid dispensing openings 10 which are located (only) over the first portion 4a of the heat exchanger 4, the cleaning fluid dispensing members 84, 85, 86 of the second group comprise fluid dispensing openings 10 which are located (only) over the second portion 4b of the heat exchanger 4, and the cleaning fluid dispensing members 87, 88, 89 of the third group comprise fluid dispensing openings 10 which are located (only) over the third portion 4c of the heat exchanger 4.
The cleaning fluid dispensing members 81 - 89 can be supplied with cleaning fluid by means of a cleaning fluid intake line 11 and a cleaning fluid pump 12 arranged in the cleaning fluid intake line 11. The cleaning fluid intake line 11 branches into a first fluid conduit 13a, a second fluid conduit 13b and a third fluid conduit 13c, and each of the fluid conduits 13a, 13b, 13c is provided with a corresponding fluid supply valve 14a, 14b, 14c. After the fluid supply valves 14a, 14b, 14c, each of the fluid conduits 13a, 13b, 13c connects to a respective manifold 15a, 15b, 15c, where the fluid conduits 13a, 13b, 13c branch into the cleaning fluid dispensing members of a respective one of the three groups of cleaning fluid dispensing members 81-83, 84-86 and 87-89. In particular, the first fluid conduit 13a branches into the cleaning fluid dispensing members 81-83 of the first group of cleaning fluid dispensing members at the first manifold 15a, the second fluid conduit 13b branches into the cleaning fluid dispensing members 84-86 of the second group of cleaning fluid dispensing members at the second manifold 15b, and the third fluid conduit 13c branches into the cleaning fluid dispensing members 87-89 of the third group of cleaning fluid dispensing members at the third manifold 15c.
For cleaning a selected portion 4a, 4b, 4c of the heat exchanger 4 the corresponding fan 6a, 6b, 6c is deactivated, the cleaning fluid pump 12 is activated and the fluid supply valve 14a, 14b, 14c corresponding to the selected portion 4a, 4b, 4c of the heat exchanger 4 is opened.
For example, if the first portion 4a of the heat exchanger 4 is to be cleaned, the fan 6a is deactivated, the cleaning fluid pump 12 is activated and the fluid supply valve 14a is opened. As a result, cleaning fluid from the cleaning fluid intake line 11 is supplied by the cleaning fluid pump 12 through the open fluid supply valve 14a to the first group of cleaning fluid conduits 81 - 83 having fluid dispensing openings 10 which are located (only) above the selected portion 4a of the heat exchanger 4.
The additional fluid supply valves 14b, 14c corresponding to portions 4b, 4c of the heat exchanger 4, which are not selected for cleaning, are closed so that no cleaning fluid is supplied to the fluid conduits 84 - 89 having fluid dispensing openings 10 which are located over the not selected portions 4b, 4c of the heat exchanger 4.
The cleaning operation has been described exemplarily for the first portion 4a of the heat exchanger 4 but of course it can be realized similarly for the second and third portions 4b, 4c of the heat exchanger 4.
As a result, each portion 4a, 4b, 4c of the heat exchanger 4 may be cleaned individually and only one fan associated to a single portion of the heat exchanger 4 has to be deactivated for cleaning, while the additional fans may continue to operate. It is therefore not necessary to stop the operation of the heat exchanger 4 and the refrigeration circuit completely.
In order to distribute the cleaning fluid over the whole surface of the respective portion 4a, 4b, 4c of the heat exchanger 4 to be cleaned, the cleaning fluid dispensing members 81 - 89 may be rotated/pivoted around their longitudinal axis by means of a drive unit 18. The drive unit 18 may be driven by an (electric) motor 20 or alternatively by the cleaning fluid flowing through the cleaning fluid dispensing members 81 - 89.
Preferably, the cleaning fluid dispensing members 81 - 89 are not rotated over a full circle of 360 degrees but only over an angle of less then 180 degrees so that the cleaning fluid dispensed by the cleaning fluid dispensing members 81 - 89 is always supplied to the air outlet side 5b of the heat exchanger 4 and not dispensed in the direction of the fans 6a, 6b, 6c arranged above the cleaning fluid dispensing members 81 - 89.
The drive unit 18 may be configured to rotate/pivot all of the cleaning fluid dispensing members 81 - 89 together, i.e. to rotate even cleaning fluid dispensing members 81 - 89 which are actually dispensing no fluid since the corresponding fluid supply valve 14a, 14b, 14c is closed. Such a drive unit 18 driving all fluid dispensing members 81 - 89 together is easy to implement.
Alternatively the drive unit 18 may drive only the group of activated fluid dispensing members 81 - 89, e.g. those fluid dispensing members 81 - 89 which are actually dispensing cleaning fluid to the heat exchanger 4. It is also possible that a separate drive unit 18 is associated to each group of fluid dispensing members 81 - 89.
The drive unit(s) 18 may be further configured to rotate the fluid dispensing members 81 - 89 parallel to each other or alternatively in a counter rotating manner in order to provide an optimized cleaning of the heat exchanger 4.
The self cleaning heat exchanger device 2a according to the first embodiment further comprises a control unit 30 which is configured to control the fans 6a, 6b, 6c, the valves 14a, 14b, 14c, the cleaning fluid pump 12 and the drive unit 18 in order to allow a proper cleaning of the heat exchanger 4.
The fluid conduits 13a, 13b, 13c fluidly connecting the outlet of the cleaning fluid pump 12 to the fluid supply valves 14a, 14b, 14c are fluidly connected to a drain conduit 17 comprising a drain valve 16 allowing to drain all the cleaning fluid from the cleaning fluid intake line 11 and/or the cleaning fluid dispensing members 81 - 89. The fluid conduits 13a, 13b, 13c and the cleaning fluid dispensing members 81 - 89 may be drained e.g. for maintenance or in order to avoid freezing of the cleaning fluid within the cleaning fluid dispensing members 81 - 89 when ambient temperatures drops below the freezing point of the cleaning fluid.
In the first embodiment of a self cleaning heat exchanger device 2a shown in Figures 1 and 2 even the cleaning fluid dispensing members 81 - 86 which have no fluid dispensing openings 10 located above the third portion 4c of the heat exchanger 4 extend over the whole width of the heat exchanger 4, i.e. over all three portions 4a, 4b, 4c. This allows to support the cleaning fluid dispensing members 81 - 89 easily and symmetrically at both lateral ends of the heat exchanger 4.
In the embodiment shown in Figure 2 all cleaning fluid dispensing members 81 - 89 have the same weight and a similar configuration as they differ only in the positions of the fluid dispensing openings 10. Therefore, the cleaning fluid dispensing members 81 - 89 can be manufactured and mounted easily and at low costs.
In an alternative embodiment, which is not shown in the figures, the cleaning fluid dispensing members 81 - 86, which have no fluid dispensing openings 10 over the third portion 4c of the heat exchanger 4 extend only as long as it is necessary for covering the respective associated portion 4a, 4b of the heat exchanger 4. Thus, the cleaning fluid dispensing members 81 - 86 associated to the first and second portions 4a, 4b of the heat exchanger 4 may be shorter in order to save the material for the distal end portion that does not comprise any fluid dispensing openings 10. In such an embodiment, however, additional supports located at the end of the respective portion 4a, 4b of the heat exchanger 4 are necessary.
Figure 3 shows a schematic side view of a self cleaning heat exchanger device 2b according to a second embodiment of the invention.
The features of the self cleaning heat exchanger device 2b according to the second embodiment which are identical to the features of the self cleaning heat exchanger device 2a according to the first embodiment shown in Figures 1 and 2 are denoted with the same reference signs and will not be discussed in detail again.
The self cleaning heat exchanger device 2b according to the second embodiment comprises a heat exchanger 4 extending basically horizontally and being supported by two supports 3 similar to the heat exchanger 4 of the first embodiment. Three fans 6a, 6b, 6c which are configured for sucking air through associated portions 4a, 4b, 4c of heat exchanger 4 and which can be activated and deactivated individually are arranged above the heat exchanger 4, as well.
In the space between the upper air outlet side 5b of the heat exchanger 4 and the fans 6a, 6b, 6c at least one cleaning fluid dispensing member 93 extends substantially parallel to the upper air outlet side 5b of the heat exchanger 4.
As in the first embodiment the cleaning fluid dispensing member 93 comprises a plurality of fluid dispensing openings 10 for dispensing cleaning fluid from the cleaning fluid dispensing member 93 to the air outlet side 5b of the heat exchanger 4 facing the fans 6a, 6b, 6c and the cleaning fluid dispensing member 93.
Differently from the first embodiment, the self cleaning heat exchanger device 2b according to the second embodiment does not comprise different groups of cleaning fluid dispensing members 81 - 89 which are respectively associated to one of the portions 4a, 4b, 4c of the heat exchanger 4 and comprise fluid dispensing openings 10 at different positions located along the axial expansion of the cleaning fluid dispensing members 81 - 89.
Instead, switchable inlet valves 23a, 23b, 23c and one-way valves 26a, 26b are arranged along the axial direction of the cleaning fluid dispensing member 93 allowing to selectively dispense fluid from the cleaning fluid dispensing member 93 to each of the portions 4a, 4b, 4c of the heat exchanger 4.
The principle of operation of a self cleaning heat exchanger device 2b according to the second embodiment is described in more detail with reference to the top view shown in Figure 4.
The cleaning device according to the second exemplary embodiment comprises three cleaning fluid dispensing members 91, 92, 93 extending basically parallel to each other over the whole width of the heat exchanger 4, i.e. over all three portions 4a, 4b, 4c of the heat exchanger 4.
As in the top view of the first embodiment shown in Figure 2 the fans 6a, 6b, 6c have been removed in order to give an unobstructed view onto the heat exchanger 4 and the cleaning device formed by cleaning fluid dispensing members 91, 92, 93.
In operation cleaning fluid from the cleaning fluid intake line 11 is supplied by means of a cleaning fluid pump 12 to each of the cleaning fluid dispensing members 91, 92, 93 over a manifold 15 where the cleaning fluid intake line 11 branches into the three cleaning fluid dispensing members 91, 92, 93.
Each of the cleaning fluid dispensing members 91, 92, 93 comprises a plurality of fluid dispensing openings 10 for respectively dispensing cleaning fluid to each portion 4a, 4b, 4c of the heat exchanger 4 which is located below the cleaning fluid dispensing members 91,92,93.
In the exemplary embodiment shown in Figure 4 the cleaning fluid is supplied to the dispensing members 91, 92, 93 from the right side of the heat exchanger 4 and each of the cleaning fluid dispensing members 91, 92, 93 respectively comprises three fluid dispensing openings 10 over each of the three portions 4a, 4b, 4c of the heat exchanger 4.
Each of the cleaning fluid dispensing members 91, 92, 93 comprises a first section 91a, 92a, 93a arranged over the first portion 4a of the heat exchanger 4, a second section 91b, 92b, 93b arranged over a second portion 4b of the heat exchanger 4 and a third section 91c, 92c, 93c arranged over the third portion 4c of the heat exchanger 4.
First inlet valves 21a, 22a, 23a are respectively arranged in each of the cleaning fluid dispensing members 91, 92, 93 at the right (inlet) side of the first sections 91a, 92a, 93a of the fluid dispensing members 91, 92, 93 in order to allow fluid supplied by the cleaning fluid pump 12 to enter into the first sections 91a, 92a, 93a of the respective cleaning fluid dispensing member 91, 92, 93 if the respective first inlet valves 21a, 22a, 23a are open and to block the flow of fluid into said first sections 91a, 92a, 93a by closing the first inlet valves 21a, 22a, 23a.
The self cleaning heat exchanger device 2b according to the second embodiment further comprises bypass lines 41, 42, 43 respectively connected to one of the cleaning fluid dispensing members 91, 92, 93 upstream of the first inlet valves 21a, 22a, 23a.
Thus, if the first inlet valves 21a, 22a, 23a are closed, fluid supplied by the cleaning fluid pump 12 may bypass the closed first inlet valves 21a, 22a, 23a and the first sections 91a, 92a, 93a of the cleaning fluid dispensing members 91, 92, 93 and enter into the second sections 91b, 92b, 93b and/or third sections 91c, 92c, 93c of the cleaning fluid dispensing members 91, 92, 93 via the bypass lines 41, 42, 43, respectively.
Second inlet valves 21b, 22b, 23b and third inlet valves 21c, 22c, 23c are arranged at the (right-side) inlet side of the second sections 91b, 92b, 93b and, respectively, third sections 91c, 92c, 93c in order to selectively allow or disallow fluid supplied by the cleaning fluid pump 12 via the respective bypass line 41, 42, 43 to flow into the second sections 91b, 92b, 93b and third sections 91c, 92c, 93c in order to be dispensed over the second and/or third portion 4a, 4b, 4c of the heat exchanger 4, respectively.
One-way valves 24a, 25a, 26a, 24b, 25b, 26b are arranged at the (left-side) outlet sides of the first sections 91a, 92a, 93a and second sections 91b, 92b, 93b of the cleaning fluid dispensing members 91, 92, 93 in order to disallow fluid to flow from the bypass lines 41, 42, 43 into the respective first sections 91a, 92a, 93a and second sections 91b, 92b, 93b of the cleaning fluid dispensing members 91, 92, 93 when the respective inlet valves 21a, 22a, 23a, 21b, 22b, 23b are closed.
By selectively opening the first inlet valves 21a, 22a, 23a, the second inlet valves 21b, 22b, 23b and/or the third inlet valves 21c, 22c, 23c fluid from the cleaning fluid intake line 11 may be directed selectively to the first sections 91a, 92a, 93a, the second sections 91b, 92b, 93b and/or the third sections 91c, 92c, 93c of the cleaning fluid dispensing members 91, 92, 93 in order to respectively clean the associated portions 4a, 4b, 4c of the heat exchanger 4.
Thus, as in the first embodiment shown in Figures 1 and 2, each portion of the heat exchanger 4 may be cleaned independently of the other portions and there is no need to deactivate the heat exchanger 4 completely for cleaning. As a result, the refrigeration circuit comprising a heat exchanger device 2b according to the second embodiment may continue to operate even while a cleaning operation is performed.
As in the first embodiment of the self cleaning heat exchanger device 2a of the first embodiment the cleaning fluid dispensing members 91, 92, 93 of the self cleaning heat exchanger device 2b according to the second embodiment may be rotated/pivoted around their respective longitudinal axis by means of at least one drive unit 18 in order to distribute the cleaning fluid over the whole area of the respective portion 4a, 4b, 4c of the heat exchanger 4.
Again, the cleaning fluid dispensing members 91, 92, 93 are preferably not rotated over a full circle of 360 degrees but only over an angle of less then 180 degrees so that the cleaning fluid dispensed by the cleaning fluid dispensing members 91, 92, 93 is always supplied to the air outlet side 5b of the heat exchanger 4 and not dispensed in the direction of the fans 6a, 6b, 6c arranged above the cleaning fluid dispensing members 91, 92, 93.
In the embodiments shown in the figures the heat exchanger 4 is arranged substantially horizontally and the cleaning fluid dispensing members 8, 9 are arranged on top of the heat exchanger 4.
The skilled person, however, will understand that it is also possible to arrange the heat exchanger 4 substantially vertically and to configure the fans 6a, 6b, 6c to suck the air in a horizontal direction through the heat exchanger 4. In this case the cleaning fluid dispensing members 81 - 89, 91 - 93 may be arranged in parallel to a vertical oriented air outlet side 5b of the heat exchanger 4 facing the fans 6a, 6b, 6c in order to dispense the cleaning fluid to said air outlet side 5b of the heat exchanger 4. Air ducts formed within the heat exchanger 4, which are provided in order to allow air to flow through the heat exchanger 4, may be inclined with respect to the horizontal in order to allow the cleaning fluid dispensed by the cleaning fluid dispensing members 8, 9 to flow through and out of the heat exchanger 4.
The heat exchangers 4 according to the exemplary embodiments described before with reference to the figures are divided in three portions 4a, 4b, 4c with corresponding fans 6a, 6b, 6c which may be activated and deactivated separately. Of course, any other number of portions 4a, 4b, 4c and fans 6a, 6b, 6c, which appears to be convenient for the actual configuration, may be realized. Dividing the heat exchanger 4 in a large number of portions 4a, 4b, 4c reduces the loss of the heat-exchanger's 4 capacity when one of the fans 6a, 6b, 6c is deactivated for cleaning the corresponding portion 4a, 4b, 4c of the heat exchanger 4, but it increases the complexity of the cleaning device formed by the fluid dispensing members 81-89, 91-93 as additional pipes and/or valves will be necessary.
A self cleaning heat exchanger device according to the described embodiments is easy to manufacture and to maintain. It furthermore allows to reliably clean the entire surface of the heat exchanger. A method for automatically cleaning a heat exchanger device according to the described embodiments is easy to implement at low costs and allows to reliably clean the surface of the heat exchanger completely.
A self cleaning heat exchanger device according to the described embodiments in particular does not comprise any parts which need to be exactly adjusted and may block in case of an insufficient adjustment or spoilage. It further allows to clean the air outlet side of the heat-exchanger completely as it does not comprise any "blind spots" which are not covered by the cleaning device.
A self cleaning heat exchanger device according to the described embodiments will result in less high-pressure failures in particular during the summer, when the full capacity of the heat exchanger is needed and there is a lot of dust in the air spoiling the surface of the heat exchanger. The costs for maintenance are reduced and an increased energy consumption, which is caused when the temperature of the refrigerant leaving the heat exchanger is high due to a reduced cooling capacity, is avoided.
In one embodiment the heat-exchanger is a liquefier/condenser. A liquefier/condenser is used in subcritical refrigerant circuits in which the refrigerant is condensed from the gas phase to the liquid phase.
According to a further embodiment of the invention, the heat-exchanger is an air-cooled liquefier. An air-cooled liquefier is easy and cheap to implement.
According to a further embodiment of the invention, the cleaning fluid comprises water. Water provides a convenient cleaning fluid, which is available at low costs. As the described embodiments of the invention are based on a cleaning system but not on a spray-system no pretreatment of the water is necessary. The cleaning fluid may comprise additional cleaning additives in order to enhance the cleaning capabilities of the cleaning fluid.
According to a further embodiment of the invention a self cleaning heat exchanger device comprises at least two cleaning fluid dispensing members. A plurality of cleaning fluid dispensing members allows to reliably clean the complete outer surface of the heat exchanger. A plurality of cleaning fluid dispensing members further allows to selectively clean only a portion of the heat exchanger by activating only one or a selected group of the plurality of cleaning fluid dispensing members.
In another embodiment of a self cleaning heat exchanger device the cleaning fluid dispensing member(s) is/are formed in a tube-shape. Tube-shaped cleaning fluid dispensing members may be arranged conveniently over the surface of the heat exchanger. They are also easy to produce at low costs as they can be manufactured from ordinary pipes.
According to a further embodiment a self cleaning heat exchanger device comprises at least two heat exchangers or heat exchanger portions. A self cleaning heat exchanger device comprising at least two heat exchangers or heat exchanger portions allows to deactivate only one or a selected group of the fans associated to said at least two heat exchangers or heat exchanger portions for cleaning while the additional fan(s) continue(s) to operate. Thus, the heat exchanger is still active and there is no need to stop the operation of the refrigeration circuit when the heat exchanger is cleaned.
According to a further embodiment of the invention a self cleaning heat exchanger device comprises a least two fans, each of the fans being associated to one of the heat exchangers or heat exchanger portions and configured to suck air (only) through the associated heat exchanger or heat exchanger portion. The fans may be configured to be activated and deactivated individually.
Such a configuration allows to stop only the fan(s) associated to the heat exchanger(s) or heat exchanger portion(s) to be cleaned. The fan(s) associated to the heat exchanger(s) or heat exchanger portion(s) which are actually not cleaned may continue to operated allowing to continue to run the refrigeration circuit even during cleaning.
According to a further embodiment of the invention the number of fans is equal to the number of heat-exchangers or heat exchanger portions. This allows a single fan to be associated to each of the heat-exchangers or heat exchanger portions. Thus, only the fan associated to the heat-exchanger or the heat exchanger portion to be cleaned needs to be deactivated while all additional fans may continue to operate supplying fresh are to the active heat-exchanger(s) or heat exchanger portion(s).
According to a further embodiment of the invention at least two cleaning fluid dispensing members are provided per heat exchanger or heat exchanger portion, said cleaning fluid dispensing members being configured for cleaning the associated heat exchanger or heat exchanger portion, respectively. This allows to clean the exchangers or heat exchanger portions separately with the additional heat exchangers or heat exchanger portions continuing to operate during the cleaning operation.
In an embodiment of a heat exchanger device the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion have cleaning fluid dispensing openings which are arranged (only) over the respective heat exchanger or over the respective heat exchanger portion. This allows to dispense fluid from each of the cleaning fluid dispensing members (only) to an associated respective heat exchanger or heat exchanger portion. Thus, each of the heat exchangers or heat exchanger portions may be cleaned separately by activating (only) the associated cleaning fluid dispensing member.
In an embodiment of a heat exchanger device at least one of the cleaning fluid dispensing members is provided for one respective heat exchanger or heat exchanger portion. This allows an easy operation and control of the cleaning fluid dispensing members in order to supply cleaning fluid to only one of the heat exchangers or heat exchanger portions.
In an embodiment of a heat exchanger device all the cleaning fluid dispensing members extend substantially parallel to each other. This allows an easy assembly of the cleaning fluid dispensing members.
In an embodiment of a heat exchanger device at least the cleaning fluid dispensing members provided for one respective heat exchanger or heat exchanger portion, particularly all the cleaning fluid dispensing members, are configured to rotate in parallel or synchronously to each other. Alternatively at least two adjacent cleaning fluid dispensing members provided for one respective heat exchanger or heat exchanger portion may be configured to rotate anti-parallel to each other or in a counter-rotating manner. Rotating at least one of the cleaning fluid dispensing members allows to dispense the fluid over the whole surface of the associated heat exchanger or heat exchanger portion.
In an embodiment of a heat exchanger device at least one of the cleaning fluid dispensing members extends over all the heat exchangers or heat exchanger portions. In an embodiment of a heat exchanger device all cleaning fluid dispensing members extend over all the heat exchangers or heat exchanger portions. The cleaning fluid dispensing members may extend over all the heat exchangers or heat exchanger portion transversally over the broader side of the air outlet side. This allows to easily mount and support the cleaning fluid dispensing members over the heat exchanger.
In an embodiment the heat exchanger device comprises a joint cleaning fluid pump and a joint cleaning fluid intake line for supplying the cleaning fluid to the cleaning fluid dispensing members to be activated. A cleaning fluid pump, which may be a high-pressure pump, allows to pressurize the cleaning fluid supplied to the cleaning fluid dispensing members to an increased pressure in order to enhance the cleaning capability of the cleaning fluid supplied to the surface of the heat exchanger to be cleaned.
In an embodiment of the heat exchanger device the cleaning fluid intake line branches into individual cleaning fluid lines leading to respective cleaning fluid dispensing members. In an embodiment each of the individual cleaning fluid lines connects to the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion. This allows to supply cleaning fluid individually to each of the cleaning fluid dispensing members and in particular to selectively supply cleaning fluid to the cleaning fluid dispensing members associated to a selected heat exchanger or heat exchanger portion in order to clean (only) the selected heat exchanger or heat exchanger portion.
According to a further embodiment of the invention, the cleaning fluid dispensing members are configured to be activated and deactivated individually, in particular by means of at least one valve, in particular a solenoid valve. This allows to individually activate each of the cleaning fluid dispensing members and in particular to selectively activate (only) the cleaning fluid dispensing member(s) associated to a selected heat exchanger or heat exchanger portion in order to clean (only) the selected heat exchanger or heat exchanger portion, respectively.
According to a further embodiment of the invention, the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion are configured to be activated and deactivated together, in particular by means of at least one valve, especially a solenoid valve provided in the cleaning fluid line to which the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion connect. This reduces the number of necessary valves and ensures that all dispensing members associated to a selected heat exchanger or heat exchanger portion are activated together in order to ensure a complete cleaning of the selected heat exchanger or heat exchanger portion.
According to a further embodiment of the invention, each cleaning fluid dispensing member comprises at least two sections each of the sections comprising fluid dispensing openings over only one of the heat exchangers or a portion of a heat exchanger. The self cleaning heat exchanger device further comprises valves arranged in the cleaning fluid dispensing members. The valves allow to activate and deactivate each section of the cleaning fluid dispensing members individually in order to dispense fluid only to the associated portion of the heat exchanger. This allows to individually clean portions of the heat exchanger even with a small number of cleaning fluid dispensing members.
According to a further embodiment of the invention, at least one of the fluid dispensing openings of a cleaning fluid dispensing member is formed as a nozzle. A nozzle allows to dispense the fluid effectively from the cleaning fluid dispensing member for efficiently cleaning the heat exchanger. In particular, the nozzle may be designed to concentrate the cleaning fluid in a strong stream or jet for removing even sticky dirt from the surface of the heat exchanger.
According to a further embodiment of the invention, at least one cleaning fluid dispensing member comprises a plurality of fluid dispensing openings. A plurality of fluid dispensing openings allows to dispense the cleaning fluid from a single cleaning fluid dispensing member to a large area of the surface of the heat exchanger.
According to an embodiment of the invention a self cleaning heat exchanger device comprises at least one drive unit which is configured for rotating the cleaning fluid dispensing member(s), in particular to rotate together the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion. Rotating the cleaning fluid dispensing members by means of a drive unit allows to reliably dispense the cleaning fluid over the whole surface of the heat exchanger covered by the respective cleaning fluid dispensing member(s).
The drive unit may comprise an (electric) motor for rotating the cleaning fluid dispensing member(s). Driving the drive unit by means of a motor allows to rotate the cleaning fluid dispensing members independently of the pressure provided by the fluid and does not reduce the fluid's pressure for driving the fluid dispensing members. The whole pressure of the fluid is available for cleaning the surface of the heat exchanger. The motor may be an electric motor.
Alternatively the drive unit may rotate the cleaning fluid dispensing member(s) by means of the pressure of the cleaning fluid flowing through the cleaning fluid dispensing members) in order to save the costs for providing a motor. A cleaning device without a motor also does not need an electrical power supply.
According to a further embodiment of the invention, the self cleaning heat exchanger device comprises at least one drain for draining the cleaning fluid from the cleaning fluid dispensing members in order to empty the cleaning fluid dispensing members for maintenance or at low temperatures in order to prevent the cleaning fluid from freezing inside the leaning fluid dispensing members at low ambient temperatures.
According to a further embodiment of the invention, the self cleaning heat exchanger device comprises a control unit which is configured to switch the fans, the valves, the pump and the motor. The control unit may ensure a coordinated operation of the the fans, the valves, the pump and the motor.
According to a further embodiment of the invention, the self cleaning heat exchanger device comprises at least one temperature sensor. The embodiment may in particular comprise an air temperature sensor located at the air inlet side of the heat exchanger, which is configured for sensing the temperature of air flowing into the heat exchanger, and/or a refrigerant temperature sensor located at the refrigerant outlet line, which is configured for sensing the temperature of the refrigerant flowing out of the heat exchanger. The control unit may trigger the cleaning of at least on of the heat exchangers or heat exchanger portions based on the measured temperature(s) and in particular on the difference between the temperatures respectively measured by the air temperature sensor and the refrigerant temperature sensor.
According to a further embodiment of the invention, the control unit is configured to individually switch off the fans, to switch on the pump and to individually switch the valves and the motor to operate the cleaning fluid dispensing members provided per heat exchanger or heat exchanger portion, in case a measured temperature at the heat exchanger deviates from an expected temperature by more than a tolerable level. This allows an effective cleaning of spoiled portions of the heat exchanger when the performance of the heat exchanger is derogated more than a tolerable level.
According to a further embodiment of the invention, the control unit is configured to count the number of cleaning circles and to issue a service message when a predetermined number of of cleaning circles is reached in order to cause a service person to visit the site and check and maintain the cleaning system.
According to a further embodiment of the invention, the method of cleaning a heat exchanger comprising at least two heat exchangers or heat exchanger portions and associated fans which are configured for sucking air through the respectively associated heat exchanger portion further comprises the steps of deactivating the fan associated to a heat exchanger or heat exchanger portion and dispensing and distributing the fluid onto said heat exchanger or heat-exchanger portion. Deactivating the fan of the heat exchanger or heat exchanger portion to be cleaned allows an effective cleaning of the respective heat exchanger or heat exchanger portion as it avoids that the cleaning fluid provided by the cleaning fluid dispensing member is sucked by the fan and prevented from flowing through the heat exchanger.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalence my be substitute for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention is not limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the pendent claims.

Reference Numerals

2a: first embodiment of the heat exchanger device
2b: second embodiment of the heat exchanger device
3: support
4: heat exchanger
4a, 4b, 4c: first, second, third portion of the heat exchangers
5a: air inlet side of the heat exchanger
5b: air outlet side of the heat exchanger
6a, 6b, 6c: first, second, third fans
10: fluid dispensing opening
11: cleaning fluid intake line
12: fluid pump
13a, 13b, 13c: first, second, third fluid conduits
14a, 14b, 14c: first, second, third fluid supply valves
15a, 15b, 15c: first, second, third manifolds
15: manifold
16: drain valve
17: drain conduit
18: drive unit
20: motor
21a, 22a, 23a: inlet valves (first portion)
21b, 22b, 23b: inlet valves (second portion)
21c, 22c, 23c: inlet valves (third portion)
24a, 25a, 26a: one-way valves (first portion)
24b, 25b, 26b: one-way valves (second portion)
30: control unit
32: refrigerant inlet line
34: refrigerant outlet line
36: refrigerant temperature sensor
38: air temperature sensor
41, 42, 43: bypass lines
81 - 89: cleaning fluid dispensing members (first embodiment)
91, 92, 93: cleaning fluid dispensing members (second embodiment)
91a, 92a, 93a,: first sections of the fluid dispensing members
91b, 92b, 93b,: second sections of the fluid dispensing members
91c, 92c, 93c,: third sections of the fluid dispensing members

Claims

Refrigeration circuit circulating a refrigerant and comprising in the direction of the flow of the refrigerant a compressor, a heat rejecting heat exchanger device (2a; 2b), an expansion device and an evaporator, wherein the heat rejecting heat exchanger device (2a; 2b) is a
self cleaning heat exchanger device (2a; 2b) comprising:
at least two heat exchangers (4) or at least one heat exchanger (4) comprising at least two heat exchanger portions (4a, 4b, 4c), each heat exchanger (4) having an air inlet side (5a) and an air outlet side (5b);

at least one fan (6a, 6b, 6c); and

at least one cleaning fluid dispensing member (81-89; 91-93), in particular at least two cleaning fluid dispensing members (81-89; 91-93);

characterized in that

the at least one fan (6a, 6b, 6c) is arranged adjacent the air outlet side (5b) of the heat exchanger (4) and configured for sucking air through the at least one heat exchanger (4) with the at least one cleaning fluid dispensing member (81-89; 91-93) being arranged between the air outlet side (5b) of the at least one heat exchanger (4) and the at least one fan (6a, 6b, 6c); and

the at least one cleaning fluid dispensing member (81-89; 91-93)
comprises fluid dispensing openings (10) for dispensing a cleaning fluid onto the at least one heat exchanger (4), in particular onto the air outlet side (5b) of the at least one heat exchanger (4);

extends along and is rotatable around an axis that extends substantially parallel to the air outlet side (5b) of the at least one heat exchanger (4) in order to distribute the cleaning fluid over the at least one heat exchanger (4), in particular over the air outlet side (5b) of the at least one heat exchanger (4);

comprises at least two sections (91a-c, 92a-c, 93a-c) each of the sections (91a-c, 92a-c, 93a-c) comprising fluid dispensing openings (10) arranged over only one of the at least two heat exchangers (4) or over only one portion (4a, 4b, 4c) of the at least one heat exchanger (4), and valves (21a-c, 22a-c, 23a-c) which are configured for allowing individually activating and deactivating each section (91a-c, 92a-c, 93a-c) of each cleaning fluid dispensing member (91-93).
Refrigeration circuit of claim 1 , wherein at least one cleaning fluid dispensing member (81-89; 91-93) is formed in a tube-shape.
Refrigeration circuit of any of the preceding claims, comprising at least two fans (6a, 6b, 6c), wherein each of the fans (6a, 6b, 6c) is associated to one of the heat exchangers (4) or heat exchanger portions (4a, 4b, 4c) and configured to suck air through the associated heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), and wherein the fans (6a, 6b, 6c) are in particular configured to be activated and deactivated individually.
Refrigeration circuit of claim 3, wherein at least two cleaning fluid dispensing members (81-89; 91-93) are provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), said cleaning fluid dispensing members (81-89; 91-93) being configured for cleaning the associated heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), respectively, wherein the cleaning fluid dispensing members (81-89; 91-93) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c) in particular have cleaning fluid dispensing openings (10) arranged over the respective heat exchanger (4) or over the respective heat exchanger portion (4a, 4b, 4c).
Refrigeration circuit of claim 3 or 4, wherein at least the cleaning fluid dispensing members (81-89; 91-93) provided for one respective heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), particularly all the cleaning fluid dispensing members (81-89; 91-93), extend substantially parallel to each other.
Refrigeration circuit of any of claims 3 to 5, wherein at least the cleaning fluid dispensing members (81-89; 91-93) provided for one respective heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), particularly all the cleaning fluid dispensing members (81-89; 91-93), are configured to rotate in parallel or synchronously to each other, or wherein at least two adjacent cleaning fluid dispensing members (81-89; 91-93) provided for one respective heat exchanger (4) or heat exchanger portion (4a, 4b, 4c) are configured to rotate anti-parallel to each other or in a counter-rotating manner.
Refrigeration circuit of any of claims 3 to 6, wherein at least one of the cleaning fluid dispensing members (81-89; 91-93) extends over all the heat exchangers (4) or heat exchanger portions (4a, 4b, 4c).
Refrigeration circuit of any of the preceding claims, comprising a cleaning fluid pump (12) and a cleaning fluid intake line (11) for supplying cleaning fluid to the cleaning fluid dispensing members (81-89; 91-93), wherein the cleaning fluid intake line (11) in particular branches into individual cleaning fluid conduits (13a, 13b, 13c) respectively leading to corresponding cleaning fluid dispensing members (81-89; 91-93), and wherein each of the individual cleaning fluid conduits (13a, 13b, 13c) in particular connects to the cleaning fluid dispensing members (81-89) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c).
Refrigeration circuit of any of the preceding claims, wherein the cleaning fluid dispensing members (81-89) are configured to be activated and deactivated individually, in particular by means of at least one fluid supply valve (14a, 14b, 14c), especially a solenoid valve, or wherein the cleaning fluid dispensing members (81-89) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c) are configured to be activated and deactivated together, in particular by means of at least one fluid supply valve (14a, 14b, 14c), especially a solenoid valve provided in the cleaning fluid conduit (13a, 13b, 13c) to which the cleaning fluid dispensing members (81-89) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c) connect.
Refrigeration circuit of any of the preceding claims, wherein at least one of the fluid dispensing openings (10) of a cleaning fluid dispensing member (81-89; 91-93) is formed as a nozzle.
Refrigeration circuit of any of the preceding claims comprising at least one drive unit (18) which is configured for rotating the cleaning fluid dispensing members (81-89; 91-93), in particular to rotate together the cleaning fluid dispensing members (81-89; 91-93) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c).
Refrigeration circuit of any of the preceding claims, further comprising at least one drain conduit (17) which is configured for draining the cleaning fluid from the cleaning fluid dispensing members (81-89; 91-93).
Refrigeration circuit of any of the preceding claims, further comprising, a control unit (30) which is configured for switching the fans (6a, 6b, 6c), the valves (14a, 14b, 14c), the pump (12) and the drive unit (18), and at least one temperature sensor (36, 38) arranged at the heat exchanger (4), in particular an air temperature sensor located at the air inlet side of the heat exchanger and/or a refrigerant temperature sensor (36) located at the refrigerant outlet line (34), wherein the control unit (30) is configured to individually switch off the fans (6a, 6b, 6c), to switch on the pump (12) and to individually switch on the inlet fluid supply (14a, 14b, 14c) and the drive unit (18) to operate the cleaning fluid dispensing members (81-89; 91-93) provided per heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), in case a measured temperature at the heat exchanger (4) deviates from an expected temperature by more than a tolerable level.
Method of cleaning a heat exchanger device (2a; 2b) of a refrigeration circuit, the heat exchanger device (2a; 2b) comprising:
at least two heat exchangers (4) or at least one heat exchanger (4) comprising at least two heat exchanger portions (4a, 4b, 4c), each heat exchanger (4) having an air inlet side (5a) and an air outlet side (5b);at least one fan (6a, 6b, 6c) arranged adjacent the air outlet side (5b) of the heat exchanger (4) and configured for sucking air through the at least one heat exchanger (4); and at least one cleaning fluid dispensing member (81-89; 91-93), in particluar at least two cleaning fluid dispensing members (81-89; 91-93) being arranged between the air outlet side (5b) of the at least one heat exchanger (4) and the at least one fan (6a, 6b, 6c)wherein the at least one cleaning fluid dispensing member (81-89; 91-93)comprises fluid dispensing openings (10) for dispensing a cleaning fluid onto the at least one heat exchanger (4), in particular onto the air outlet side (5b) of the at least one heat exchanger (4);extends along and is rotatable around an axis that extends substantially parallel to the air outlet side (5b) of the at least one heat exchanger (4) in order to distribute the cleaning fluid over the at least one heat exchanger (4), in particular over the air outlet side (5b) of the at least one heat exchanger (4);comprises at least two sections (91a-c, 92a-c, 93a-c) each of the sections (91a-c, 92a-c, 93a-c) comprising fluid dispensing openings (10) arranged over only one of the at least two heat exchangers (4) or over only one portion (4a, 4b, 4c) of the at least one heat exchanger (4), and valves (21a-c, 22a-c, 23a-c) which are configured for allowing individually activating and deactivating each section (91a-c, 92a-c, 93a-c) of each cleaning fluid dispensing member (91-93), the method comprising the steps of
rotating at least one cleaning fluid dispensing member (81-89; 91-93) arranged between an air outlet side (5b) of the at least one heat exchanger (4) and the at least one fan (6a, 6b, 6c) and extending along an axis that extends substantially parallel to the air outlet side (5b) of the at least one heat exchanger (4), around said axis; and

dispensing and distributing the cleaning fluid from the at least one rotating cleaning fluid dispensing member (81-89; 91-93) onto one of the heat exchanger (4) or heat exchanger portions (4a, 4b, 4c), in particular over the air outlet side (5b) of the at least one heat exchanger (4), by opening the respectively associated valves (21a-c, 22a-c, 23a-c).
Method according to claim 14, wherein
the heat exchanger device (2a; 2b) comprises at least two fans (6a, 6b, 6c) associated with the heat exchangers (4) or heat exchanger portions (4a, 4b, 4c) and being configured for sucking air through the respectively associated heat exchanger (4) or heat exchanger portion (4a, 4b, 4c), and wherein
the method comprises deactivating the at least one fan (6a, 6b, 6c) associated with a heat exchanger (4) or heat exchanger portion (4a, 4b, 4c) and dispensing and distributing the fluid onto said heat exchanger (4) or heat-exchanger portion (4a, 4b, 4c).