Dry cooler

Abstract

A dry cooler, comprising at least one basic structure (2), forming at least one region (3) for heat exchange between air and a fluid to be cooled. The heat exchange region (3) has at least one air intake (4) and at least one air outlet (5), both communicating with the external environment. There are means (6) for generating at least one air flow (6a) along at least one path extending from the intake (4) to the outlet (5), and a heat exchange stage (7) which is arranged along the air path and has at least one heat exchange duct (7a), inside which the fluid to be cooled circulates, and an adiabatic air cooling stage (8) arranged upstream of the heat exchange stage (7) and configured to cool the air intended to pass through the heat exchange stage (7); downstream of the heat exchange stage (7), along the direction of advancement of the air flow (6a) along its path, there are at least one additional heat exchange stage (7) and at least one additional adiabatic cooling stage (8), the additional adiabatic cooling stage (8) being arranged upstream of the additional heat exchange stage (7) along the direction of advancement of the air flow (6a) along its path.

Description

[0001] DRY COOLER

[0002] The present invention relates to a dry cooler.

[0003] Air cooling apparatuses, also known as dry coolers, are known which make it possible to cool a process fluid by means of an air flow.

[0004] In general, dry coolers typically comprise a heat exchange stage, typically constituted by a finned pack heat exchanger, inside which the fluid to be cooled circulates, and means for generating an air flow which is forced through the heat exchange stage.

[0005] Dry coolers are commonly used both in the civil and in the industrial sector, since they allow significant energy savings with respect to other types of cooling apparatus, such as chillers with refrigerant circuit.

[0006] The effectiveness of dry coolers is linked to the geographical area of installation and varies according to the seasons and climate conditions, since heat exchange occurs with ambient air in most cases.

[0007] In order to meet cooling requirements even when environmental conditions are unfavorable due to high temperatures, dry coolers can be provided with an adiabatic cooling stage, which allows to exploit the evaporation of water in order to lower the temperature of the air flow that reaches the heat exchange stage.

[0008] In this case, before being sent to the heat exchange stage, the ambient air is passed through the adiabatic cooling stage, where it encounters water which, by evaporating, absorbs heat from the air, thus reducing the temperature of the air and increasing its humidity content to a final value which depends on the efficiency of the adiabatic cooling stage itself.

[0009] According to the background art, the adiabatic cooling stage of dry coolers can be constituted, for example, by water nebulizers, which spray water in the opposite direction to the air flow, reaching a water saturation in the air of 60-80%.

[0010] Alternatively, the adiabatic cooling stage of dry coolers is provided by using a humid material, typically constituted by humidified panels, also called “pads,” which are kept wet and allow to increase the relative humidity of the air that passes through them, reaching water saturation levels in the air of between 70 and 90%.

[0011] It is also known to provide the adiabatic cooling stage of dry coolers by means of hybrid systems that combine humidified panels and nebulizers that spray water against the air flow or directly onto the finned pack exchanger that provides the heat exchange stage.

[0012] In this case, saturation levels very close to 100% can usually be achieved, thus allowing the air to be cooled to temperatures close to the wet bulb temperature, but special treatment of the finned pack heat exchanger is required to prevent degradation and corrosion thereof.

[0013] The efficiency of the adiabatic cooling performed by the adiabatic stage of dry coolers depends on various factors, including environmental factors such as the dry bulb temperature and the relative humidity of the outside air.

[0014] In particular, the adiabatic stage of dry coolers has better performance in hot, dry climates and may be less effective in humid climates, as the already humid air has a limited capacity to absorb additional moisture.

[0015] Moreover, it requires a constant supply of water to keep the material humid, and this may not be ideal in areas with water scarcity.

[0016] Typically, these apparatuses operate in dry mode for most of the year, and the adiabatic cooling stage only operates when it is very hot.

[0017] Last but not least, the adiabatic cooling stage of dry coolers is generally unable to achieve high cooling rates and bring the air temperature to values at least close to those of the wet bulb temperature, unless hybrid systems are used, which, however, have the drawback of being very expensive, as well as requiring protection of the finned pack heat exchanger, as mentioned above.

[0018] In addition to dry coolers, other known ventilated heat exchangers that exploit adiabatic cooling are constituted by cooling towers. In cooling towers, the fluid to be cooled exchanges heat with the ambient air, in which the relative humidity is increased up to saturation, so that the actual air temperature is therefore equal to the wet bulb temperature.

[0019] Cooling towers allow the fluid to be cooled extremely quickly, just above the wet bulb temperature of the air, but have many disadvantages.

[0020] Firstly, cooling towers consume a lot of water, since during operation they require constant water replenishment to compensate for the water that evaporates to saturate the air.

[0021] Secondly, cooling towers have high maintenance costs. In fact, they require constant maintenance with chemical agents, since they constitute an ideal environment for the formation of limescale and algae accumulations.

[0022] Another problem associated with cooling towers is that if not properly treated they become the ideal habitat for the proliferation of Legionella, which is a risk to human health.

[0023] The aim of the present invention is to provide a dry cooler that is capable of improving the background art in one or more of the above aspects.

[0024] Within this aim, an object of the invention is to provide a dry cooler capable of offering improved cooling capacity with respect to the background art for the same exchange surface area, air flow rate and overall dimensions.

[0025] Another object of the invention is to provide a dry cooler that has a smaller footprint than similar background art apparatuses with the same cooling capacity.

[0026] A further object of the present invention is to provide a dry cooler capable of exhibiting reduced electrical consumption compared to the background art.

[0027] Another object of the invention is to provide a dry cooler that has reduced water consumption with respect to the background art constituted by cooling towers. Another object of the invention is to provide a dry cooler that is constructively simple to provide.

[0028] Moreover, an object of the present invention is to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

[0029] Not least object of the invention is to provide a dry cooler which is highly reliable and has a competitive production cost.

[0030] This aim, as well as these and other objects that will become more apparent hereinafter, are achieved by a dry cooler according to claim 1, optionally provided with one or more of the characteristics of the dependent claims.

[0031] Further characteristics and advantages of the invention will become more apparent from the description of some preferred but not exclusive embodiments of the dry cooler according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

[0032] Figure 1 is a top plan view of the dry cooler according to the invention;

[0033] Figure 2 is a front elevation view of the dry cooler according to the invention;

[0034] Figure 3 is a sectional view, taken along the plane III-III of Figure 2;

[0035] Figure 4 is a sectional view, taken along the plane IV-IV of Figure 1;

[0036] Figure 5 is a sectional view, taken along the plane V-V of Figure 1;

[0037] Figure 6 is an enlarged-scale view of a detail of Figure 5;

[0038] Figure 7 is a lateral elevation view of the dry cooler according to the invention;

[0039] Figure 8 is a lateral elevation view of the dry cooler according to the invention from the opposite side with respect to Figure 7;

[0040] Figures 9 to 18 are schematic sectional views of different embodiments of the dry cooler according to the invention;

[0041] Figure 19 is a schematic sectional view of the dry cooler according to the invention, showing a possible embodiment of the adiabatic cooling stages;

[0042] Figure 20 is an enlarged-scale view of a detail of Figure 19;

[0043] Figure 21 is a chart that plots, by way of example, a possible temperature behavior of the air and the fluid to be cooled in the dry cooler according to the invention;

[0044] Figure 22 is an enlarged-scale view of a detail of a possible embodiment of the apparatus according to the invention.

[0045] With reference to the figures, the dry cooler according to the invention, generally designated by the reference numeral 1, comprises at least one basic structure 2, which forms at least one region 3 for heat exchange between the air and a fluid to be cooled.

[0046] For example, the fluid to be cooled is constituted by a heat exchange fluid coming from a thermal user device that needs to be cooled and with which it has exchanged heat, heating up.

[0047] In particular, the heat exchange region 3 has at least one air intake 4 and at least one air outlet 5, both of which communicate with the external environment.

[0048] The dry cooler moreover comprises means 6 for generating at least one air flow 6a along at least one path extending from the intake 4 towards the outlet 5.

[0049] Along the path of the air flow 6a there is a heat exchange stage 7, which has at least one heat exchange duct 7a, which is externally skimmed by the air flow 6a and inside which the fluid to be cooled flows.

[0050] Moreover, upstream of the heat exchange stage 7, in the direction of advancement of the air flow 6a along its path, there is an adiabatic air cooling stage 8, which is configured to cool the air that is intended to pass through the heat exchange stage 7.

[0051] One of the particularity of the invention resides in that it comprises, again along the path of the air flow 6a in the heat exchange region 3, from the intake 4 to the outlet 5, and downstream of the heat exchange stage 7, along the direction of the air flow 6a, at least one additional heat exchange stage 7 and at least one additional adiabatic cooling stage 8, with the additional adiabatic cooling stage 8 arranged upstream of the additional heat exchange stage 8, again in the direction of advancement of the air flow 6a along its path within the heat exchange region 3.

[0052] Advantageously, with this structure, the dry cooler according to the invention has, along the path of the air flow 6a within the heat exchange region, in contrast to the background art, a plurality of heat exchange stages

[0053] 7, upstream of each of which, along the direction of advancement of the air flow 6a along its path, there is at least one respective adiabatic cooling stage

[0054] 8.

[0055] In practice, the dry cooler according to the invention is conveniently provided with at least one alternation of adiabatic cooling stages 8 and heat exchange stages 7, which can be crossed in succession by the air flow 6a along its path from the intake 4 toward the outlet 5 of the heat exchange region 3.

[0056] Advantageously, the heat exchange ducts 7a of the heat exchange stages 7 are connected in series to each other and conveniently are connected to a single cooling circuit in a heat exchange relationship with the thermal load to be cooled.

[0057] However, there is nothing to prevent them from being connected in parallel with each other and, in this case, being connected to cooling circuits that are independent of each other.

[0058] Conveniently, the heat exchange stages 7 and the adiabatic cooling stages 8 can extend along respective planes, which can be substantially parallel to each other, as in the examples of Figures 9-16, or inclined with respect to each other, as in the examples of Figures 17 and 18.

[0059] The heat exchange stages 7 and the adiabatic cooling stages 8 may be arranged, with their planes of arrangement, substantially at right angles to the path of the air flow 6a or may also be arranged inclined, with their planes of arrangement, with respect to the path of the air flow 6a.

[0060] Going into greater detail, according to one possible embodiment, such as for example the one shown in Figures 1 and 2, the basic structure 2 of the dry cooler may have a longitudinal extension.

[0061] In this case, the intake 4 and the outlet 5 can be conveniently positioned on sides of the basic structure 2 that are arranged along directions which are substantially perpendicular to the longitudinal extension of the basic structure 2.

[0062] The basic structure 2 may also be composed of multiple modular bodies 2a, conveniently having a substantially box-like shape, which can be assembled in various configurations, so as to make the dry cooler according to the invention more easily transportable and versatile.

[0063] For example, the modular bodies 2a can be assembled mutually side by side so as to form the longitudinal extension of the basic structure 2.

[0064] Advantageously, each modular body 2a of the basic structure 2 can form internally at least one respective portion of the heat exchange region 3 and can moreover conveniently have at least one corresponding intake 4 and at least one corresponding outlet 5, preferably arranged on mutually different sides of the same modular body.

[0065] It is also possible to provide, for each of the modular bodies 2a that make up the basic structure 2, respective means 6 for generating at least one respective air flow 6a, but it is also possible to provide that the generator means 6 may be associated only with one or some of the modular bodies 2a.

[0066] According to possible embodiments of the dry cooler according to the invention, the generator means 6 may also be capable of generating at least two distinct air flows 6a which pass through respective heat exchange regions 3 along respective paths.

[0067] In this case, along the path of each of the air flows 6a generated by the generator means 6, a respective alternation of adiabatic cooling stages 8 and heat exchange stages 7 is conveniently interposed.

[0068] In particular it is possible for example to provide, as in the embodiment shown by way of example in Figure 3, that at least two air intakes 4 are formed in the basic structure 2 and are positioned, for example, on mutually opposite sides of the basic structure 2 and are formed along a direction which is transverse to the longitudinal extension of the basic structure 2.

[0069] In this example, the air intakes 4 can each be crossed by respective air flows 6a, which are generated by the generator means 6 and are conveyed along respective paths, through a respective alternation of adiabatic cooling stages 8 and heat exchange stages 7, until they both flow out at a common outlet 5, located on one side of the basic structure 2, which is arranged along a direction which is perpendicular both to said transverse direction along which the intakes 4 are located and with respect to the longitudinal extension of the basic structure 2.

[0070] Other possible structures and arrangements of the elements of the dry cooler according to the invention are shown, again by way of example, in Figures 11, 12, 15, and 16.

[0071] The generator means 6 are conveniently provided with one or more fans 11.

[0072] For example, the fans 11 may be positioned in a row along the longitudinal extension of the basic structure 2.

[0073] Two or more rows of fans 11 may also optionally be provided.

[0074] Conveniently, the fans 11 are positioned at the air outlets 5, thus working by suction on the heat exchange region 3, but there is nothing to prevent them from being positioned at the intakes 4 and working so as to deliver towards the heat exchange region 3.

[0075] The diameter of the fans 11 may be defined so as to ensure the best performance in relation to the dimensions of the basic structure 2 as well as the lowest noise level. Preferably, for the provision of the generator means 6 and more particularly of the fans 11, the use of EC electronic fans or AC fans controlled by an inverter, internal or external to the fans themselves, is envisaged, so as to ensure maximum energy savings during the adjustment step with respect to alternative adjustment systems.

[0076] Conveniently, at each of the adiabatic cooling stages 8 there are means capable of creating at least one layer of water that can be crossed by the air flows 6a.

[0077] Preferably, the adiabatic cooling stages 8 comprise respective adiabatic panels 8a of a type known per se, suitably humidified, which provide the layer of water.

[0078] Advantageously, the adiabatic panels 8a used to provide the adiabatic cooling stages 8 may have a thickness substantially comprised between 50 mm and 300 mm, more preferably 150 mm, so as to ensure the best performance without exceeding the predetermined dimensions.

[0079] Conveniently, the adiabatic panels 8a can be humidified by means of water dispensing means 12, such as, for example, ramps of nozzles 12a (i.e., portions of duct along which multiple nozzles are mounted), perforated pipes or perforated trays, advantageously placed above the adiabatic panels themselves.

[0080] Conveniently, easily accessible housing compartments for the adiabatic panels 8a are formed in the basic structure 2 to allow rapid replacement of the panels themselves when necessary.

[0081] It should be noted that the adiabatic cooling stages 8 can also be provided solely by nozzle ramps capable of creating layers of nebulized water that can be crossed by the air flows 6a or by a combination of adiabatic panels 8a and nozzle ramps.

[0082] According to one possible embodiment, shown in Figures 19 and 20, it is also possible to provide that the adiabatic cooling stages 8 can each be provided by a plurality of nebulizing nozzles 14 which are configured to emit jets of nebulized water in the direction of the heat exchange stages 7 that are adjacent thereto.

[0083] Conveniently, as shown in Figure 22, water collection elements, such as for example trays or basins 9, are provided below the adiabatic cooling stages 8, so that the water that does not evaporate during the adiabatic cooling of the air carried out in the adiabatic cooling stages 8 can be collected by the basins 9 and conveyed, at least in part, into a recirculation system 10, thus ensuring minimal water consumption, or discharged.

[0084] Advantageously, the heat exchange stages 7 can be provided by finned pack heat exchange units.

[0085] In particular, the heat exchange units providing the heat exchange stages 7 extend substantially parallel to the longitudinal extension of the basic structure 2.

[0086] More particularly, at the longitudinal ends of the basic structure 2, the heat exchange units providing the heat exchange stages 7 are conveniently connected to respective intake / output manifolds 13, which allow to distribute and collect from the finned pack units the fluid to be cooled, which passes through the heat exchange stages 7.

[0087] Preferably, the heat exchange units of each heat exchange stage 7 are connected to each other so as to form a single cooling circuit.

[0088] It is also possible for the heat exchange units crossed by one of the air flows 6a generated by the generator means 6 to be connected to a different cooling circuit with respect to the heat exchange units crossed by another air flow 6a also generated by the generator means 6.

[0089] As an alternative to finned pack heat exchange units, other types of heat exchange units may optionally be used to provide the heat exchange stages 7, such as for example microchannels, finned tubes or any other technology that allows heat exchange between air and a fluid.

[0090] The operation of the dry cooler according to the invention is as follows. The ambient air is drawn in through the intake 4 by the generator means 6, which generate at least one air flow 6a in the heat exchange region 3.

[0091] The air flow 6a generated by the generator means 6 passes in sequence through a first adiabatic cooling stage 8, where it undergoes a first cooling, and a first heat exchange stage 7, where it exchanges heat with the fluid to be cooled, cooling the fluid to be cooled and consequently undergoing significant heating.

[0092] Subsequently, before reaching the outlet 5 and therefore the external environment, the air flow 6a is passed, in sequence, through at least one second adiabatic cooling stage 8, where it is cooled again, and at least one second heat exchange stage 7, where it exchanges heat again with the fluid to be cooled, further cooling the fluid to be cooled and undergoing, in turn, further significant heating.

[0093] If they are present, the air flow 6a may also optionally pass in succession through further adiabatic cooling stages 8 and further heat exchange stages 7 before returning to the external environment.

[0094] Figure 17 shows a possible behavior of the temperatures of the air and of the fluid to be cooled in the dry cooler according to the invention.

[0095] It should be noted that air motion may be in countercurrent with respect to the fluid to be cooled, but the apparatus may also be provided to operate in equicurrent, although in this case the efficiency in dry operation is lower.

[0096] In practice it has been found that the invention achieves the intended aim and objects, providing an apparatus capable of exhibiting a greater cooling capacity with respect to standard adiabatic systems with the same exchange surface, air flow rate, and overall dimensions, as well as a lower water and electricity consumption and a smaller overall size.

[0097] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

[0098] In particular, it should be noted that the dry cooler according to the invention, although it has been designed primarily for liquid cooling systems, may also be validly applied to condensers, i.e., devices inserted in refrigeration circuits where the refrigerant desuperheats, condenses, and subcools inside the tubes.

[0099] All the details may furthermore be replaced with other technically equivalent elements.

[0100] In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

[0101] The disclosures in Italian Patent Application No. 102024000018688 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

CLAIMS1. A dry cooler, comprising:- at least one basic structure (2), forming at least one region (3) for heat exchange between air and a fluid to be cooled, said heat exchange region (3) having at least one air intake (4) and at least one air outlet (5), both communicating with the external environment;- means (6) for generating at least one air flow (6a) along at least one path extending from said intake (4) to said outlet (5);- a heat exchange stage (7) arranged along said path and having at least one heat exchange duct (7a), inside which said fluid to be cooled circulates;- an adiabatic air cooling stage (8) arranged along said path, upstream of said heat exchange stage (7) along the direction of advancement of the air flow (6a) along said path, and configured to cool the air intended to pass through said heat exchange stage (7); characterized in that it comprises, along said air path, downstream of said heat exchange stage (7), along the direction of advancement of the air flow (6a) along said path, at least one additional heat exchange stage (7) and at least one additional adiabatic cooling stage (8), said additional adiabatic cooling stage (8) being arranged upstream of said additional heat exchange stage (7) along the direction of advancement of the air flow (6a) along said path.

2. The apparatus according to claim 1, characterized in that the heat exchange ducts (7a) of said heat exchange stages (7) are connected in series to each other.

3. The apparatus according to claim 1, characterized in that it comprises, along said air path, a plurality of heat exchange stages (7), upstream of each of said heat exchange stages (7), at least one respective adiabatic cooling stage (8) being arranged along the direction of advancement of the air flow (6a) along said path.

4. The apparatus according to claim 1, characterized in that it comprises at least one alternation of adiabatic cooling stages (8) and heat exchange stages (7), which can be crossed in succession by the air in its path from said intake (4) toward said outlet (5).

5. The apparatus according to claim 1, characterized in that said means (6) for generating at least one air flow are adapted to generate at least two distinct air flows (6a) that cross said at least one heat exchange region (3) along respective paths, a respective alternation of adiabatic cooling stages (8) and heat exchange stages (7) being interposed along the path of each of said air flows (6a).

6. The apparatus according to claim 1, characterized in that it comprises, at each of said adiabatic cooling stages (8), means for creating at least one layer of water that can be crossed by the air flow (6a).

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