Patent Description:
More specifically, the invention is intended for generating potable water using ambient air.

In <CIT>, a water extraction device (<NUM>) for extracting water from ambient air (<NUM>), with a adsorption element for adsorbing water from an inlet air flow (<NUM>) obtained from the ambient air (<NUM>) and for delivering water to a moist air flow (<NUM>) guided through the water extraction device (<NUM>) is presented.

<CIT> discloses a water making device that collects the moisture contained in the atmosphere and condenses it into high purity water. In one embodiment of this prior art document, moist air entering the water making/water cooling system flows across an air filter, then a precooler heat exchanger and then a water extraction heat exchanger, where the air stream is cooled further and water is extracted. The water that leaves water extraction heat exchanger is collected in a water collection device and passes from there through a primary water filter into a water storage tank. The air stream then passes across a reheat heat exchanger and exhausted to the outside. A water circulation pump extracts water from the water storage tank and circulates the water stream through an evaporator of a vapor compression refrigeration system, where the water stream is chilled, then through the water extraction heat exchanger and precooler, where the incoming air stream is chilled by removing heat to the water stream. The water stream is then circulated through the reheat heat exchanger, where the water stream is again cooled by removing heat to the cool dry air exiting the water extraction heat exchanger. The cooled water stream is circulated through the water filter to a three way valve, that directs water flow either to a dispenser or back to the water storage tank.

Devices are already known for generating potable water, such as, for example, water purification plants or desalination plants.

Such known installations have the drawback that, for this purpose, impure liquid water is required.

Atmospheric water generators are also known, which require energy and humid ambient air to generate saline and/or potable water.

This has the advantage that such generators can be used on locations where there is little or no impure liquid water present.

Passive systems are known which do not require electrical or mechanical external energy.

A disadvantage is that they require a large space and surface area, making them unsuitable for large-scale water production.

Active systems are also known, which are able to generate a cooling capacity using electrical or mechanical energy to cool ambient air to below the dew point.

Such systems use a cooling circuit comprising a coolant or refrigerant, such as, for example, fluorocarbons.

The efficiency of such a cooling circuit decreases sharply when the difference between the ambient temperature and the cooling temperature increases.

In environments with high ambient temperatures and low humidity and hence a low dew point, the efficiency of such systems is therefore relatively low.

In addition, the liquid coolants used are often harmful to the environment.

The present invention aims to provide a solution to at least one of the aforementioned and other drawbacks.

The present invention has as object a device for extracting water from humid ambient air according to the first claim, and has as object a method for extracting water from humid ambient air according to the ninth claim.

Alternatively formulated, the device comprises a conduit in which successively is incorporated : a compressor having an inlet for humid ambient air, a primary portion of a first condenser, an expander and secondary portion of a second condenser, wherein a secondary portion of the first condenser is configured to direct humid ambient air through it as coolant, wherein a primary portion of the second condenser is configured to direct humid, ambient air to be dried through it.

In this device water will be generated at two locations, namely in a first stage and in a second stage. The air drawn in and compressed by the compressor will be cooled in the first condenser by the ambient air, whereby water will be separated off. This is possible because, together with the pressure, also the temperature of the ambient air increases due to the compression. The compressed ambient air will therefore have a higher temperature compared to the non-compressed ambient air. This non-compressed ambient air can subsequently be used as coolant to cool the compressed ambient air. The cooling will continue until the dew point such that water is extracted from the compressed ambient air in a first stage. The compressed ambient air is thereby dried into dried compressed air.

It should therefore be further understood that preferably no phase change occurs during the compression of the humid ambient air.

In a next step, the dried compressed air is expanded into dry expanded air. Due to the expansion, the temperature will decrease again, that is, the temperature of the expanded air will be lower than the dried compressed air.

After expansion, this dried and expanded air is then used as cooling air or coolant in the second condenser, separating off water from the again humid ambient air flowing through this second condenser.

An advantage is that no liquid, harmful coolant is required, but that ambient air is used for cooling. The device is therefore safer for man and environment.

Another advantage is that the performance or efficiency of such a device is comparable to known devices, even when the ambient temperature is high, but that the proposed solution is much cheaper and thus economically much more interesting.

Yet another advantage consists in that such a device is very simple and cheap to produce. Moreover, the cost per generated amount of water is also lower.

This is, on the one hand, because there is no need for a liquid harmful coolant, which entails strict safety requirements, but on the other hand also because the device does not comprise a closed cycle.

According to an embodiment, an inlet conduit is connected to an inlet of the primary portion of the second condenser, wherein a primary portion of a first heat exchanger is incorporated, wherein an outlet of the primary portion of the second condenser is connected to the inlet of a secondary portion of the first heat exchanger via a first conduit, wherein an outlet of the secondary portion of the second condenser is connected to the inlet of the secondary portion of the first heat exchanger via a second conduit.

According to an embodiment, a secondary portion of a second heat exchanger is incorporated into said second conduit, wherein the primary portion of this second heat exchanger is incorporated in said inlet conduit, between the primary portion of the first heat exchanger and the primary portion of the second condenser.

According to an embodiment, the expander is provided with a generator for generating energy, which generator is coupled to a drive of the compressor for supplying it with energy.

In order to better demonstrate the features of the invention, some preferred embodiments of a device and method according to the invention for extracting water from humid ambient air are described below, by way of example without any limiting character, with reference to the accompanying drawings, in which :.

The device shown schematically in <FIG> for generating water according to the invention comprises a conduit <NUM> in which the following elements are successively incorporated:.

Said compressor <NUM> is in this case, but not necessarily, an oil-free compressor <NUM>. This has the advantage that no oil can end up in the air and the condensate separated therefrom.

The secondary portion <NUM> of the first condenser <NUM> is configured to direct humid ambient air there through as coolant.

To this end, in this case, but not necessarily for the invention, a fan, such as a first fan <NUM>, is provided.

Furthermore, the first condenser <NUM> is provided with a drain <NUM> for condensate formed in the primary portion in the first stage, to extract water from the humid ambient air.

The primary portion <NUM> of the second condenser <NUM> is configured to direct humid ambient air to be dried through it.

This means that the expanded, dried air will serve as cooling air in this second condenser <NUM>.

In order to be able to direct the humid ambient air to be dried through the primary portion <NUM> of the second condenser <NUM>, a second fan, in this case fan <NUM>, is provided. This second fan <NUM> is also not necessary for the invention.

Thus, both the first fan <NUM> and the second fan <NUM> may be replaced, for example, by a blower or any other type of machine, configured to cause a flow. The first <NUM> and second <NUM> fan may also comprise the same machine and effect the flow in the first condenser <NUM> and the second condenser <NUM> via a set of flow guides.

The second condenser <NUM> is, just like the first condenser <NUM>, provided with a drain <NUM> for condensate formed in the primary portion <NUM> in a second stage for extracting water from humid ambient air.

In this case, but not necessarily, an inlet conduit <NUM> is connected to the inlet <NUM> of the primary portion <NUM> of the second condenser <NUM> in which a primary portion <NUM> of a first heat exchanger <NUM> is incorporated.

The outlet <NUM> of the primary portion <NUM> of the second condenser <NUM> is connected to the inlet <NUM> of the secondary portion <NUM> of the heat exchanger <NUM> via a first conduit <NUM>.

The outlet <NUM> of the secondary portion <NUM> of the second condenser <NUM> is also connected to the inlet <NUM> of the secondary portion <NUM> of the heat exchanger <NUM> via a second conduit <NUM>.

The operation of the device <NUM> is as follows.

The compressor <NUM> will draw in and compress humid ambient air, causing it to heat up.

This warm, humid, compressed air then passes through the primary portion <NUM> of the first condenser <NUM>, where it is cooled by ambient air, using the first fan <NUM>, to its dew point.

Condensate, i.e. water, will be formed here, which is removed from the device <NUM> via the outlet <NUM>. This is a first point or stage at which water is produced or generated.

The dried air is then expanded via the expander or the expansion valve <NUM> and further cooled by this expansion.

This expanded air has a lower temperature than the ambient air and is directed through the secondary portion <NUM> of the second condenser <NUM> to cool humid ambient air to below the dew point.

This humid ambient air is directed through the primary portion <NUM> of this second condenser <NUM>, wherein it first passes through the primary portion <NUM> of the heat exchanger <NUM>. To this end, use will be made here of the second fan <NUM>.

When cooling the humid ambient air in the second condenser <NUM>, condensate will be formed in a second point or stage, which is removed from the device <NUM> via the outlet <NUM>. This is a second point at which water is produced or generated.

Both the expanded air, which emerges from the secondary portion <NUM> of the second condenser <NUM>, and the dried air, which emerges from the primary portion <NUM> of the second condenser <NUM>, have a temperature around the dew point of the ambient air.

Both gases are directed via the first conduit <NUM> and second conduit <NUM> to the secondary portion <NUM> of the heat exchanger <NUM>.

Hereby, a first cooling of the humid ambient air will already take place before the cooling to the dew point takes place in the second condenser <NUM>.

The air which is used for cooling in the first condenser <NUM> and in the heat exchanger <NUM> is afterwards simply vented into the atmosphere.

In <FIG> an alternative arrangement is shown.

Hereby, the expander <NUM> is provided with a generator <NUM> for generating energy.

The generator <NUM> will be driven by the expander <NUM> during the expansion process such as to recover energy from the expansion process.

The generator <NUM> is coupled to a drive <NUM> of the compressor <NUM> in order to supply it, whether or not partially, with energy. The remaining energy demand of the generator can then be met, for example, via solar panels. Furthermore, the generator may also provide energy for the first <NUM> and/or the second <NUM> ventilator.

In this way, the energy, which is generated during the expansion process, is optimally recovered.

Of course, it cannot be excluded that the generator <NUM> supplies the generated energy to an electricity grid.

Furthermore, in <FIG> a second heat exchanger <NUM> is also provided.

The secondary portion <NUM> of this second heat exchanger <NUM> is incorporated into said second conduit <NUM>, wherein the primary portion <NUM> of this second heat exchanger <NUM> is incorporated into said inlet conduit <NUM>, between the primary portion <NUM> of the first heat exchanger <NUM> and the primary portion <NUM> of the second condenser <NUM>.

In this way, the humid ambient air, which is directed to the second condenser <NUM> via the inlet conduit <NUM>, will undergo an additional cooling in the second heat exchanger <NUM> after a first cooling in the first heat exchanger <NUM>.

The expanded gas entering the second conduit <NUM> from the secondary portion <NUM> of the second condenser <NUM>, will first provide for a cooling in the second heat exchanger <NUM> and subsequently in the first heat exchanger <NUM>.

Of course, it is also possible that more than two of such heat exchangers <NUM>, <NUM> are provided.

The operation of this device <NUM> is further analogous to the device <NUM> shown in <FIG>.

The features of the invention are further illustrated using process parameters of the method as illustrated in <FIG>.

<FIG> illustrates the temperature <NUM> and the relative humidity <NUM> of humid ambient air over three consecutive twenty-four hours <NUM>, <NUM>, <NUM> in a humid environment. The horizontal axis <NUM> illustrates <NUM> hours over the consecutive twenty-four hours, starting at midnight <NUM>. In the <FIG> and <FIG>, the same horizontal axis is plotted against other operating parameters illustrating the method.

At the point in time <NUM> the temperature <NUM> starts to decrease to a minimum <NUM>, which is maintained for a certain period of time. Thereafter, the temperature increases <NUM> up to a maximum <NUM> in order then to decrease <NUM> again.

As illustrated in <FIG>, the temperature follows certain repeated cycles of increase and decrease, wherein it should be further understood that every twenty-four hours in itself is unique. Furthermore, this pattern is dependent of a geographical location and climatologic period.

Furthermore, <FIG> illustrates a relative humidity <NUM> of the ambient air in a similar manner as the temperature <NUM>. Here, too, a repetitive pattern can be recognized which is also dependent on a geographical location and climatological period.

<FIG> further illustrates the total water production <NUM> and the maximum system pressure <NUM> during the method of extracting water from the humid ambient air according to an embodiment of the invention. It should further be noted that the illustration of the water production <NUM> and the maximum system pressure <NUM> in <FIG> is related to the meteorological data illustrated in <FIG>. Notably, as already mentioned, the twenty-four hours illustrated on the horizontal axes in <FIG> corresponds to the twenty-four hours illustrated on the horizontal axes in <FIG>.

From the illustration in <FIG> it can be derived that there exists approximately a linear relationship between the water production <NUM> and the maximum system pressure <NUM> at comparable points in time.

In <FIG>, the water production is further split up according to the first condenser <NUM>, graph <NUM> and the second condenser <NUM>, graph <NUM>.

In <FIG>, a p,T-diagram is illustrated, which is representative for the method of extracting water from humid ambient air, as shown in the graphs of <FIG>. Here, different states per point in time during the first twenty-four hours <NUM> are displayed. The dashed line corresponds to six hours, the thick line to twelve hours and the normal line to eighteen hours. The designated numbers in <FIG> correspond to the locations with the same reference number in the device according to the invention of, for example, <FIG>. That is, the number <NUM> in <FIG> represents the condition in the second condenser <NUM> of <FIG>.

Finally, the method will be illustrated using equations expressing the working parameters.

The ambient conditions and in particular the absolute humidity can be expressed as function of the relative humidity RHamb, the ambient pressure pamb, and the ambient temperature Tamb : <MAT>.

The output temperature T<NUM> of the compressor <NUM> and hence the input of the first condenser <NUM> is: <MAT> where p<NUM> is the output pressure of the compressor <NUM> and κ is the compression modulus.

The dew point Tdew_2, this is the temperature at which condensation occurs, is then: <MAT> wherein RH<NUM> is the relative humidity after the compressor <NUM>.

The temperature T2_air of the air in the condenser <NUM> is: <MAT> where T2_air ≤ Tdew_2.

The relative humidity RH<NUM> and free water content free_water<NUM> in the compressed air are then: <MAT> <MAT>.

The amount of extracted water mwater_condenser from the compressed air in the condenser <NUM> is then: <MAT> with mair the total amount of air.

The required power P for the first condenser <NUM> is then: <MAT>.

The pressure p<NUM> at the expander <NUM>, this is the output of the first condenser <NUM>, is: <MAT> and the pressure p<NUM> and temperature T<NUM> at the output of the expander <NUM> are <MAT> <MAT>.

The temperature Tdew_4 in the second condenser <NUM>, which is the same as the dew point of the ambient air, is: <MAT> where T4_air ≥ T4 + ΔTcontribution_condenser4.

The relative humidity RH<NUM> and amount of free water content free_water<NUM> in the ambient air that is directed towards the second condenser <NUM> are then: <MAT> <MAT>.

The amount of extracted water mwater_condenser of the ambient air in the second condenser <NUM> is then: <MAT>.

The required power P for the second condenser <NUM> is then: <MAT>.

For a moderate maritime climate such as in Belgium, this gives the following values by way of illustration :.

The total water production in the first condenser <NUM> is then <NUM>-<NUM> litres per hour and the total water production in the second condenser <NUM> is then <NUM>-<NUM> litres per hour.

Claim 1:
Device for extracting water from humid ambient air, the device (<NUM>) comprising a conduit (<NUM>) in which successively is incorporated : a compressor (<NUM>) to compress the humid ambient air into compressed ambient air, a first condenser (<NUM>) to dry the compressed ambient air into dry compressed air, an expansion valve or expander (<NUM>) for expanding the dry compressed air into dry expanded air and a second condenser (<NUM>), the first condenser (<NUM>) being further configured to direct humid ambient air through it as coolant for extracting water from the compressed ambient air in a first stage via an outlet (<NUM>),
characterized in that the second condenser (<NUM>) is configured to direct the dry expanded air through it as coolant for extracting the water from the humid ambient air in a second stage by means of an outlet (<NUM>).