AIR CONDITIONER FOR PRODUCING WATER OUT OF AMBIENT AIR

Technical field

[0001 ] The invention is directed to the field of air treatment, more particularly air conditioning, e.g. conditioning the temperature and humidity of air. The invention is also directed to the field of production of water, for instance drinking water.

Background art

[0002] Prior art patent document published JPH 06307731 A1 discloses an air conditioning system comprising an air compressor, a vortex tube with an inlet fluidly connected to an outlet of the air compressor, a warm air outlet and a cold air outlet, an air blower, a heat exchanger fluidly connected to an outlet of the air blower and one of the cold and warm air outlets of the vortex tube so that the warm or cold air of the vortex tube conditions the air of the air blower. The heat exchanger forms a central passage fluidly connected to the outlet of the air blower and an outer passage fluidly connected to the warm or cold air outlet of the vortex tube. Thermoelectric elements are provided in the heat exchanger for boosting the heat exchanger. The system of that teaching is specifically designed for conditioning air.

[0003] Prior art patent document published SK 7970 Y1 discloses an apparatus for producing drinking water using a vortex tube. It comprises an air suction pipe with a filter, a heat exchanger located in the pipe, and a fan air blower at the exit of said pipe. It comprises also an air compressor fluidly connected to a tank of compressed air, and a vortex tube fed with the compressed air. The latter is separated in the vortex tube into a flow of warm air at one outlet and a flow of cold air at another outlet. The outlet of cold air is fluidly connected to the heat exchanger in the pipe. In operation, the flow of compressed air is separated into a flow of cold air by the vortex tube and cools the heat exchanger. The ambient air aspirated by the fan blower into the suction pipe contacts the heat exchanger so that its humidity is condensed on said exchanger. A drip tray is provided below the heat exchanger so as to collect the condensed water. The latter can be disinfected by a UV lamp before being stored in a tank. This teaching is interesting in that it allows to produce water, for instance drinking water, with an air conditioning device free of refrigerant. Its water production productivity is however limited by the fan blower located at the exit of the suction pipe. It is driven by a larger wind turbine and is therefore directly dependent on the wind conditions. Also, the heat exchanger of the serpentine type causes important load losses prejudicing a proper functioning of the vortex tube.

[0004] Prior art patent document published US 2011/0214434 A1 discloses an air dryer for compressed air, e.g. industrial compressed air for driving pneumatic tools and various pneumatic actuators. The air dryer comprises a cyclone chamber using the coanda effect for separating the water vapour contained in the air circulating in that chamber. It comprises also a vortex tube fed by the air exiting the cyclone chamber. The cold flow of air exiting the vortex tube is fed into a serpentine tube in the cyclone chamber for increasing the humidity separation. This air dryer in interesting in that it provides a higher level of humidity separation by a rather simple construction, i.e. producing cold air without refrigerant. It is however specifically conceived for compressed air, i.e. between 6 and 10 bar, with a limited flow rate. Also, similarly to the previous teaching, the heat exchanger of the serpentine type is disadvantageous when fluidly connected to a vortex tube because such a tube requires a very limited, if any, backpressure for a proper functioning.

Summary of invention

Technical Problem

[0005] The invention has for technical problem to provide an efficient air conditioner of a simple and compact construction, more particularly an air conditioner working without refrigerant and still providing a satisfying air conditioning capacity, e.g. for heating or cooling purposes and/or for extracting water from ambient air.

Technical solution

[0006] The invention is directed to an air conditioning system comprising: an air compressor; a vortex tube with an inlet fluidly connected to an outlet of the air compressor, a warm air outlet and a cold air outlet; an air blower; a heat exchanger fluidly connected to an outlet of the air blower and to one of the warm air outlet and the cold air outlet of the vortex tube, so that the warm or cold air of the vortex tube conditions the air of the air blower; wherein the heat exchanger comprises an outer tubular wall and an inner tubular wall inside the outer tubular wall and concentric with said wall so as to form an inner passage and an outer passage, one of said passages being fluidly connected to the outlet of the air blower and the other one of said passages being fluidly connected to one of the warm air outlet and the cold air outlet of the vortex tube.

[0007] According to a preferred embodiment, the outer passage is annular, more preferably continuous annularly over a complete turn. The cross-section of the passage can be circular or oval.

[0008] According to a preferred embodiment, the heat exchanger comprises a condensation water collecting gutter in the one of the inner or outer passages that is fluidly connected to the cold air outlet of the vortex tube, and a condensation water collecting conduit fluidly connected to said condensation water collecting gutter, so as to be configured for producing water out of ambient air.

[0009] The air-conditioning system can be a hybrid system that extracts water from ambient air and produces a flow of warm air and/or a flow of cold air.

[0010] According to a preferred embodiment, the inner passage is fluidly connected to the outlet of the air blower and the outer passage is fluidly connected to one of the warm air outlet and the cold air outlet of the vortex tube.

[0011 ] According to a preferred embodiment, the condensation water collecting gutter is on an inner side of the inner tubular wall, configured for naturally collecting the condensation water dripping by gravity along said inner side.

[0012] According to a preferred embodiment, the inner passage is fluidly connected to the cold air outlet of the vortex tube and the outer passage is fluidly connected to the outlet of the air blower.

[0013] According to a preferred embodiment, the condensation water collecting gutter is on an outer side of the inner tubular wall, configured for naturally collecting the condensation water dripping by gravity along said outer side. [0014] According to a preferred embodiment, the cold air outlet of the vortex tube is aligned with the inner passage and/or the outlet of the air blower is aligned with the outer passage.

[0015] According to a preferred embodiment, the vortex tube and the air blower are concentric.

[0016] According to a preferred embodiment, the heat exchanger is fluidly connected the cold air outlet of the vortex tube so as to cool the air of the air blower, and the heat exchanger is configured such that the outer and inner tubular walls are oriented with a vertical main component when the system is in an operative position. Alternatively, other orientations can be considered.

[0017] According to a preferred embodiment, the heat exchanger comprises a condensation water collecting conduit at a bottom position of the outer and inner tubular walls when the system is in an operative position.

[0018] According to a preferred embodiment, the heat exchanger further comprises a gutter on an inner side of the inner tubular wall, configured for naturally collecting the condensation water dripping by gravity along said inner side, said gutter being fluidly connected to the condensation water collecting conduit.

[0019] According to a preferred embodiment, the system further comprises a reservoir fluidly connected to the condensation water collecting conduit for collecting the condensed water.

[0020] According to a preferred embodiment, the system further comprises a UV disinfection unit configured to be in contact with the condensed water in the reservoir. Other and/or additional bacteriological treatment units can be provided for treating the condensed water.

[0021 ] According to a preferred embodiment, a nominal mass flow rate of the air blower is at least 5 times, preferably 7 times, more preferably 10 times, greater than a nominal mass flow rate of the air compressor.

[0022] According to a preferred embodiment, said system is configured for producing water out of ambient air.

[0023] According to a preferred embodiment, the air blower is an air amplifier fluidly connected to the outlet of the air compressor and configured for blowing air based on the coanda effect. [0024] According to a preferred embodiment, the air amplifier comprises a main conduit, a side annular inlet chamber for the compressed air with an annular passage to the main conduit, said conduit having an annular convex guiding surface directly downstream of the annular passage for achieving a coanda effect.

[0025] According to a preferred embodiment, the heat exchanger further comprises at least one fin in the outer passage and/or in the inner passage, configured for increasing heat exchange.

[0026] According to a preferred embodiment, the at least one fin is spirally shaped so as to force the air flow in the outer and/or inner passage to swirl.

[0027] According to a preferred embodiment, the air-conditioning system further comprises an air cooler fluidly connected upstream to the air compressor.

[0028] According to a preferred embodiment, the air cooler comprises a Peltier thermoelectric cooler with, when supplied with electric energy, a cold surface and a warm surface.

[0029] According to a preferred embodiment, the air-conditioning further comprises an air fan configured for cooling the warm surface of the Peltier thermoelectric cooler.

[0030] According to a preferred embodiment, the air cooler comprises a housing with an outlet of the warm surface cooling air that is fluidly connected with the warm air outlet of the of the vortex tube.

[0031 ] According to a preferred embodiment, the outer passage and/or the inner passage comprises one or more cool or heat packs configured for maintaining a low or high temperature.

[0032] According to a preferred embodiment, the one or more cool or heat packs are arranged on the inner tubular wall.

[0033] According to a preferred embodiment, the one or more cool or heat packs comprise a Phase Change Material PCM.

[0034] According to a preferred embodiment, the PCM is eutectic.

[0035] According to a preferred embodiment, the system further comprises an air filter upstream of the air blower.

[0036] According to a preferred embodiment, the inner tubular wall is corrugated along the outer tubular wall so as to increase the heat transfer between the inner and outer passages. [0037] The invention is also directed to a process for conditioning air, comprising the following actions: separating with a vortex tube a flow of compressed air into a warm gas flow and a cold gas flow; producing a flow of air through a heat exchanger; feeding the heat exchanger with one of the warm gas flow and a cold gas flow, in order to condition the flow of air; wherein the heat exchanger comprises a inner passage extending along a principal direction and an outer passage extending along said direction around the inner passage, one of said passages being fed with the flow of air and the other one of said passages being fed with the warm gas flow and a cold gas flow.

[0038] Advantageously, the process is carried out with a system according to the invention. The above features relating to the system apply to the above process.

Advantages of the invention

[0039] The invention is particularly interesting in that it provides an air conditioning system with a heat exchanger that allows a better functioning of the vortex tube, i.e. a much reduced counter pressure, compared with conventional air conditioning systems. The construction of the heat exchanger is particularly interesting for it provides easily a large chamber for the warm or cold gas flow from the vortex tube, allowing a better heat exchange and permitting to place cold or warm packs configured to increase the thermal inertia of the warm or cold source. The use of an air amplifier as air blower is also particularly interesting for it makes use of the air compressor that is readily present for the vortex tube. The inner passage is particularly adapted for the air flow from the air blower, for instance the air blower, because it causes nearly no pressure loss, if any.

Brief description of the drawings

[0040] Figure 1 is a schematic cross-sectional view of an air conditioning system according to a first embodiment of the invention.

[0041 ] Figure 2 is a schematic cross-sectional view of an air conditioning system according to a second embodiment of the invention.

Description of an embodiment

[0042] Figure 1 illustrates a first embodiment of the invention. It shows in schematic cross-sectional view an air conditioning system 2. The system 2 comprises as central component a heat exchanger 4. The latter comprises essentially an outer wall 6 and an inner wall 8 located inside the volume delimited by the outer wall 6. Each of the outer and inner walls 6 and 8 shows a closed cross-sectional profile, said profile being preferably circular, being understood that other profiles, like an oval, can be considered. Both wall outer and inner walls 6 and 8 extend along a longitudinal axis that is for instance vertical in the illustration of figure 1. The inner tubular wall 6 is preferably concentric with the outer tubular wall. In any case, both outer and inner walls 6 and 8 delimit an inner passage 10 and an outer passage 12 that is annular and surrounds the inner passage 10. The heat exchanger 4 comprises also end walls 13 for longitudinally delimiting the outer passage 12.

[0043] The system 2 comprises also a vortex tube 14, also known as the Ranque- Hilsch vortex tube. It is a mechanical device that separates a compressed gas into hot and cold gas flows. It comprises a body with an inlet 14.1 a hot or warm gas outlet 14.2 and a cold gas outlet 14.3. The body delimits a swirl chamber 14.4 in fluid connection with the inlet 14.1 and the outlets 14.2 and 14.3. In operation, pressurised gas is injected via the inlet 14.1 tangentially into the swirl chamber 14.4 and accelerated to a high rate of rotation. Due to the conical nozzle 14.5 at the end of the tube, only the outer shell of the compressed gas is allowed to escape at that end to the outlet 14.2. The remainder of the gas is forced to return in an inner vortex of reduced diameter within the outer vortex to the outlet 14.3. Such a vortex tube is well known as such to the skilled person and is also commercially available from various suppliers. It does not therefore need to be further detailed.

[0044] As this is apparent in figure 1 , the vortex tube 14 is fed at its inlet 14.1 with compressed air. The cold air outlet 14.3 is fluidly connected, e.g. via a pipe or conduit 16, to an inlet 12.1 of the outer passage 12. The warm or hot air outlet 14.2 outputs to the ambient atmosphere.

[0045] The system 2 comprises also an air blower 18, for instance an air amplifier 18 using the coanda effect for moving air, i.e. generating a flow of air to be conditioned in the heat exchanger 4. To that end, the air amplifier 18 has an outlet fluidly connected to an inlet 10.1 of the inner passage 10. In the present case, the air amplifier is directly connected to the inlet 10.1 of the inner passage 10, being however understood that it can be distant from said passage and fluidly connected with a pipe or any kind of conduit. The air amplifier 18 comprises a main body part 18.1 forming a generally circular wall forming a main conduit through which the air can pass, and a ring body part 18.2 mounted on the main body part 18.1. A filter 18.3 can be provided at the entry of the main conduit. The body parts 18.1 and 18.2 form a gas inlet 18.4 opening out to an annular chamber 18.5 which is in fluid connection with the an annular passage 18.6 to the main conduit. The main conduit has an annular convex guiding surface 18.7 directly downstream of the annular passage for achieving the coanda effect.

[0046] As this is apparent, the gas inlet 18.4 of the air amplifier 18 is fed with compressed air. In operation, compressed air fed through the inlet 18.4 and in the annular chamber 18.5 is throttled through the annular passage 18.6 so as to form a thin layer of accelerated air that adheres to the profile of the guiding surface 18.7 and that thereby turns of about 90°. The action of the high velocity of the supply air flowing along the profiles causes a pressure drop which induces a large flow of ambient air at the entry of the air amplifier. This induced flow is augmented and gains velocity by contact with the accelerated air.

[0047] As this is apparent, an air compressor 20 preferably driven by an electric motor supplies in compressed air the vortex tube 14 and the air amplifier 18. As illustrated, regulating valves 21 can be provided for varying the functional operation of each of the vortex tube 14 and the air amplifier 18. It is also conceivable to provide a specific air compressor for each of the vortex tube 14 and the air amplifier 18. The air compressor 20 can also be designed for being variable, i.e. with a variable output pressure and/or flow. The air compressor 20 and the regulating valves 21 can be controlled by a control unit 22. It is understood that the control unit 22 can be electrically connected to additional devices such as temperature and/or flow sensors at various places of the system, along the different air flows.

[0048] The inner wall 10 can comprise on its inner side, at a bottom position, a gutter 24 for collecting the condensed water flowing or dripping along said wall. A conduit 26 is provided for conveying the collected condensation water, via a pipe or any form of conduit 28, to a reservoir 30. The gutter 24 is circular and generally horizontal when the heat exchanger 4 is configured to be oriented vertically when in operation. It is however to be understood that other orientations are conceivable, in which case the gutter might need to be modified so as to be able to collect by gravity the condensed water on the inner side of the inner tubular wall 8. It might therefore take a different shape than a circular gutter as illustrated.

[0049] The heat exchanger 4 can comprise an exit pipe or conduit 32 at the outlet

10.2 of the inner passage 10 and/or an exit pipe or conduit 34 at the outlet

12.2 of the outer passage 12. For instance, the exit pipe or conduit 34 at the outlet 12.2 of the outer passage 12 can be provided with a regulating valve 36 for controlling the flow of cold air in the said passage.

[0050] The heat exchanger 4 can also be provided with one or more fins in the inner passage 10 and/or in the outer passage 12 for promoting heat exchange. For instance, a spiral-shaped fin 38 can be attached to the outer side of the inner wall 8 so as to extend in the outer passage 12 for guiding the flow of cold air and promoting heat exchange with the flow of air in the inner passage 10. This fin is preferable made of metal or at least of heat conductive material.

[0051 ] In operation, the air conditioning system of figure 1 functions as follows. The air compressor is in operation, i.e. its electric motor is supplied with electrical energy, so that it supplies the vortex tube 14 and the air amplifier 18 with compressed air. With reference to the above explanations, the flow of compressed air fed to the vortex tube 14 is separated into a warm or hot air flow to the outlet 14.2 and a cold air flow to the outlet 14.3. This flow of cold air enters the outer passage 12 and cools the inner wall 8 before exiting said passage via the outlet 12.2 and possibly the exit pipe or conduit 34. In parallel and with reference to the above explanations, the flow of compressed air fed to the air amplifier 18 generates a substantially more important flow of air towards the inner passage 10. This flow of air circulated along the inner passage 10, in contact with the inner side of the inner wall 8 which is cooled by the cold air flow of the vortex tube 14. The air circulating along and through the inner passage 10 is thereby cooled and possibly dehumidified, i.e. conditioned. The humidity contained in the air in the inner passage 10 can be condensed on the inner side of the inner wall 10 if the temperature of said wall is low enough, depending of course also of the temperature of the air and the concentration of water vapour in said air. The water condensed on the inner wall 8 will therefore flow and/or drip by gravity to the gutter 24 for being collected in a reservoir 30. The latter or any output conduit can be equipped with a disinfection unit, e.g. of the UV type, if the water is intended to be used, e.g. as drinkable water. Additional and/or alternative bacteriological water treatment units can also be used.

[0052] The above air conditioning system can therefore be used for producing cooled and dehumidified air, the condensed water being as such a by product. It can also be used primarily for collecting water, the flow of cooled air being then a by-product. In certain applications, both collected condensed water and the flow of cooled air also be main products of the system.

[0053] The concentric construction of the heat exchanger is particularly interesting in that the passage, for instance the outer one, for the cold air flow does not generate a substantial counter pressure, thereby allowing a proper functioning of the vortex tube. Also, this passage forms a buffer volume providing a certain thermic inertia. For instance, that volume can contain elements configured for increasing the thermic inertia, e.g. cool packs, like those comprising a Phase Change Material PCM. Such materials use their latent heat, i.e. the heat corresponding to a change the state of said material at constant temperature, for keeping a low temperature as along as the above energy has not be transferred. Such elements or packs are as such known to the skilled person and commercially available. They can advantageously be provided directly at the inner wall 8, i.e. thermally as close as possible to the inner passage 10 but also the outer one 12. In operation, it is indeed conceivable that the system is a portable one that can be run initially at a higher power level when supplied by a strong external source, e.g. the home or domestic electrical network, and later on at a reduced power level when running on batteries or an electrical network of a reduced available power, while still providing a proper air conditioning. These elements or packs can also comprise a eutectic material, i.e. a homogeneous mixture of substances that melts or solidifies at a single temperature that is lower than the melting point of either of the constituents. [0054] Various variations of the above configurations are conceivable, including the following ones, in any combination:

[0055] The inner and outer passages 10 and 12 can be reversed, i.e. the air flow produced by the air blower, for instance the air amplifier 18, could be fed to the outer annular passage 12 and the cold air flow of the vortex tube could be fed to the inner passage 10.

[0056] The above system is specially designed for cooling the air, in that the cold air flow of the vortex tube is fed to the heat exchanger. It is however clear that the fluid connection of the vortex tube can be reversed, i.e. the warm or hot air flow can be connected to the heat exchanger, meaning that the air moved by the air blower will be heated and not cooled anymore. Also both outlets of the vortex tube can be fluidly connected to the heat exchanger via a valve arrangement that allows switching between the cold air flow and the warm or hot air flow.

[0057] The inner wall 8 forming the barrier between the inner and outer passages 10 and 12 can be corrugated for increasing heat transfer. A corrugated profile of the wall will indeed generate turbulences in the air flow along said wall which are favourable for heat transfer.

[0058] Figure 2 illustrates a second embodiment of the invention. The reference numbers of the first embodiment are used for designating the same or corresponding elements, these numbers being however incremented by 100. It is referred to the description of these elements in relation with the first embodiment. Specific numbers comprised between 100 and 200 are used for designating specific elements.

[0059] The system 102 of the second embodiment differs from the one of the first embodiment essentially in that the connection of the inner 110 and outer passages 112 of the heat exchanger 104 to the air blower 118 and the vortex tube 114 are inverted, i.e. the inner passage 110 is fluidly connected to the outlet of the air blower 118 whereas the outer passage 112 is fluidly connected to the vortex tube 114, for instance the cold air outlet 114.3 of the vortex tube 114. As this is apparent in figure 2, the vortex tube 114 and the air blower 118 are concentric and more specifically, the air blower 1 18 surrounds the vortex tube 114. This arrangement is very compact and also reduces the heat losses in that the cold air production is directly fed to the inner passage 110 without pressure and/or heat losses.

[0060] The heat exchanger 104 can comprise an exit pipe or conduit 132 at the outlet 110.2 of the inner passage 110 and a regulating valve 136 can be provided in said exit pipe or conduit 132. Also an exit pipe or conduit (not represented) can be provided at the outlet 112.2 of the outer passage 112.

[0061 ] The system 102 of the second embodiment differs from the one of the first embodiment also in that an air cooler 142 is fluidly connected to the inlet of the air compressor 120. The latter increases the temperature of the air due to compression under adiabatic conditions and also due to internal losses tending to transfer heat to the compressed air. The air cooler 142 is for instance thermoelectric, i.e. based on the Peltier effect. The air cooler 142 comprises a housing 142.1 and at least one thermoelectric element 142.2 or thermoelectric cooler (TEC) located in the housing 142.1. Upon application of an electric voltage to the thermoelectric element 142.2, a difference in temperature will build up between the two main surfaces

142.2.1 and 142.2.2. More specifically, the surface 142.2.1 will become cold and the surface 142.2.2 will be come warm. The inlet air sucked by the air compressor 120 will flow in a first channel formed in the housing 142.1 , fluidly connected with the air compressor 120 via the outlet 142.3 and delimited by the cold surface 142.2.1 , so as to be cooled. An air fan 144 can be provided and arranged for circulating cooling air along the warm surface

142.2.2 of the thermoelectric element 142.2. That warmed cooling air can be guided via the outlet 142.4 and jointed to the warm air outlet 114.2 of the vortex tube towards a warm air outlet 146.

[0062] The above described air cooler can be applied to the first embodiment in figure 1 , in a very similar manner as to the second embodiment.