Patent Application
20250065024
The present disclosure relates generally to dialysis therapy, and in particular to a technique of producing dialysis fluid for use in dialysis therapy.
In the treatment of individuals suffering from acute or chronic renal insufficiency, dialysis therapy may be needed.
One category of dialysis therapy is extracorporeal (EC) blood therapy, in which blood from a patient is pumped through an EC blood circuit back to the patient. A blood filtration unit, commonly known as a dialyzer, is arranged in the EC blood circuit to interface the blood by a semi-permeable membrane. There are various types of EC blood therapy, including hemodialysis (HD), hemofiltration (HF), and hemodiafiltration (HDF). In HD, a treatment fluid (“dialysis fluid”) is pumped through the dialyzer. Water and substances are exchanged between the treatment fluid and the blood through the semi-permeable membrane, primarily driven by a diffusive gradient across the semi-permeable membrane. In HF, treatment fluid is not pumped through the dialyzer. Instead, a treatment fluid (“replacement fluid”) is infused into the blood in the EC blood circuit during therapy, upstream and/or downstream of the dialyzer, and fluid and substances are transported from the blood through the semi-permeable membrane, primarily by convection. In HDF, a dialysis fluid is pumped through the dialyzer, similar to HD, and a replacement fluid is infused into the blood in the EC blood circuit, similar to HF.
Another category of dialysis therapy is peritoneal dialysis (PD). In PD therapy, a treatment fluid (“dialysis fluid”) is infused into the individual's peritoneal cavity. This cavity is lined by a peritoneal membrane (“peritoneum”) which is highly vascularized. Substances are removed from the patient's blood mainly by diffusion across the peritoneum into the dialysis fluid. Excess fluid (water) is removed by osmosis induced by the dialysis fluid being hypertonic. Used or spent dialysis fluid is drained from the patient, removing waste, toxins and excess water from the patient. This cycle may be repeated, for example multiple times. There are various types of PD therapies, including continuous ambulatory PD (CAPD), automated PD (APD), tidal PD (TPD), and continuous flow PD (CFPD). CAPD is a manual dialysis treatment, in which the flow of treatment fluid into and out of the patient is driven by gravity. APD is performed by a dialysis machine, commonly known as a cycler, which is fluidly connected to the peritoneal cavity and operated to automatically transfer treatment fluid to and from the peritoneal cavity in accordance with a predefined schedule, for example during the night while the patient is sleeping.
Conventionally, treatment fluid for PD is delivered in pre-filled bags to the point-of-care, for example an intensive care unit or the home of the patient. EC blood therapy may also use pre-filled bags of treatment fluid, for example in an intensive care unit, for treatment of acute kidney failure. Treatment fluid for treatment of chronic kidney failure by EC blood therapy is typically produced by the dialysis machine itself, by mixing one or more concentrates with purified water. Recently, dialysis machines that produce treatment fluid for PD therapy have also been proposed.
Local production of treatment fluid at the point-of-care is attractive since it reduces the cost and environmental impact of transporting large amounts of ready-made treatment fluid and the burden of storing and handling pre-filled bags. However, production of treatment fluid requires access to purified water. Typically, a water purification unit is connected to a tap water source, and a fluid generation unit is operated to mix one or more concentrates with the purified water to generate the treatment fluid. Large amounts of tap water may be consumed. In PD therapy, about 15 liters of treatment fluid may be consumed daily. In EC blood therapy, more than 100 liters of treatment fluid may be consumed during a single treatment session.
To improve the patient's quality of life, and also to reduce the cost of treatment, dialysis may be performed locally in the home of the patient (“home dialysis”). As noted, local production of treatment fluid requires access to tap water, and preferably also to a drain for disposal of spent treatment fluid. Installation in the home of the patient may thus involve plumbing work to install tubing between a sanitary area and the room where treatment is performed, for example a bedroom. The plumbing work adds to the cost of treatment, and extended tubing increases the risk of leaks and consequential water damage.
Another obstacle to home dialysis is the need to purify the tap water. A water purification unit has to be installed in the patient's home, as a separate machine or included in the dialysis machine. The water purification unit is configured to process the tap water to ensure that the treatment fluid complies with quality standards, for example in terms of the content of various ions, molecules and larger particles as well as microorganisms. For example, the water purification unit may be configured to perform reverse osmosis, which increases the cost of the dialysis system as a whole.
U.S. Pat. No. 10,632,242 discloses a dialysis machine that is designed to operate in areas where resources such as energy and clean water are scarce. The dialysis machine comprises a condenser-based water generator which is powered by a solar panel to extract water from ambient air. After passing an ultrafilter, the extracted water may be mixed with concentrates to form a dialysis fluid or be used for generating saline to be infused into the patient's blood. The dialysis fluid is added as a supplement to regenerated dialysis fluid, which is produced from spent dialysis fluid by use of a sorbent device. The amount of extracted water is sufficient to produce a supplement to regenerated dialysis fluid. However, when operated indoors, the available volume of air is limited and the proposed dialysis machine is generally unable to extract water at the quantities needed to generate the PD fluid that is required for daily PD treatment of a patient. Further, extracting significant quantities of water from air in an indoor environment may lower the humidity to an extent that is uncomfortable or even unhealthy for the patient.
It is an objective to at least partly overcome one or more limitations of the prior art.
One objective is to provide a technique that facilitates treatment by dialysis therapy in an indoor environment, for example in the home of a patient.
A further objective is to provide cost-efficient system for providing treatment fluid for dialysis therapy.
One or more of these objectives, as well as further objectives that may appear from the description below, are at least partly achieved by a system for providing treatment fluid for dialysis therapy, and related methods, embodiments thereof being defined by the dependent claims.
A first aspect is a system for providing treatment fluid for dialysis therapy. The system comprises: a fluid generation unit configured to generate the treatment fluid by mixing water with one or more substances; a dehumidifier unit configured to receive a first stream of air, process the first stream of air for extraction of liquid water, and provide the liquid water for the fluid generation unit; and a humidifier unit configured to receive a second stream of air, process the second stream of air to generate a third stream of air with increased humidity compared to the second stream of air, wherein the humidifier unit is arranged to include at least part of the third stream of air in the first stream of air.
The system of the first aspect combines a dehumidifier unit with a humidifier unit that is configured to generate a humid air stream by use of tap water. The humidifier unit is thereby capable of increasing the available amount of water to be extracted by the dehumidifier unit from a given air volume. This makes the system suitable for use in an indoor environment where the available air volume may be limited. The provision of the humidifier unit also enables an acceptable air humidity to be maintained in such an indoor environment even if the dehumidifier unit should be operated to extract large quantities of water from the air. Even if tap water is required for the operation of the humidifier unit, the total amount of tap water required by the system to generate a given volume of treatment fluid may be reduced if the dehumidifier unit is operated to extract water in excess of the water that is added into the humid air stream by the humidifier unit. By configuring the system to require a reduced amount of tap water, the need for a fixed installation of tubing is mitigated since the tap water may, for example, without difficulty be manually transferred from a fixed outlet of tap water to a tank of the system.
The system opens up several possibilities to facilitate installation. In some embodiments, the humidifier unit and the dehumidifier unit are physically separated from each other, allowing them to be independently arranged within the indoor environment. For example, the humidifier unit may be located close to a fixed outlet of tap water, and the dehumidifier unit may be located close to the fluid generation unit. The transport of water from the humidifier unit to the dehumidifier unit is performed by the humid air stream that is generated by the humidifier unit. The humid air stream may be conducted in a tubing from the humidifier unit to the dehumidifier unit. Such tubing is simple to install and, since it conducts gas (air) rather than liquid water, does not significantly increase the risk of water damage. In an alternative, no tubing is used for the air transport, and the humidifier and dehumidifiers units are thus fully decoupled from each other. Instead, the humid air stream is released by the humidifier unit into its immediate surroundings, and the incoming air stream to be dehumidified is received by the dehumidifier unit from its immediate surroundings. Over time, as the system is operated, at least part of the humid air that is emitted by the humidifier unit will be transported to the dehumidifier unit, for example by natural and/or forced convection within the indoor environment. The absence of tubing between the humidifier and dehumidifier units will increase the freedom to select a convenient placement of the respective unit. In some embodiments, the humidifier and dehumidifier units are instead combined into a unitary structure and are thus co-located. The transport of the humid air stream from the humidifier unit to the dehumidifier unit may be performed in any suitable way internally of the unitary structure. The unitary combination results in a single unit which may be made compact and suitable for installation in a confined space such as a home. Further, system control may be facilitated in a system with a unitary combination of humidifier and dehumidifier units compared to a system with physically separated humidifier and dehumidifier units. In some embodiments, the dehumidifier unit comprises a desiccant which is arranged to adsorb and/or absorb water in the incoming air stream. The desiccant may be in liquid or solid form. The use of a desiccant for dehumidification enables water to be extracted in a power-efficient way. Further, compared to condenser-based dehumidification, water may be efficiently extracted from air that holds smaller amounts of moisture. In some embodiments, by proper choice of desiccant, the dehumidification unit performs an inherent purification of the extracted water. The purification is achieved by ensuring that the desiccant has a high selectivity for water and thus preferentially adsorbs and/or absorbs water molecules compared to other molecules, as well as ions and particles, present in the incoming gas stream. Such a dehumidification unit has the potential of replacing or supplementing a water treatment unit that may be required for conventional generation of treatment fluid. For example, water treatment by reverse osmosis may be obviated, resulting in cost savings.
In some embodiments, the dehumidifier unit comprises a desiccant, which is arranged to adsorb and/or absorb moisture from the first stream of air and which is processed by the dehumidification unit to extract the liquid water from the desiccant.
In some embodiments, the desiccant is configured to have a high selectivity towards water.
In some embodiments, the liquid water that is extracted from the first stream of air has conductivity of less than 10 μS/cm, and preferably less than 5 μS/cm or 1 μS/cm.
In some embodiments, the system further comprises a control arrangement, which is configured to jointly operate the humidifier unit and dehumidifier unit to achieve a set point that defines air humidity within a space that comprises the humidifier unit and the dehumidifier unit.
In some embodiments, the control arrangement is further configured to operate the dehumidifier unit to achieve a set point that defines an amount of liquid water extracted per unit time.
In some embodiments, the control arrangement is further configured to deactivate the humidifier unit and dehumidifier unit when an accumulated amount of liquid water exceeds a threshold value.
In some embodiments, the system further comprises at least one humidity sensor, which is arranged to generate a measurement signal representing the air humidity within the space.
In some embodiments, the control arrangement is configured to perform a step-response test by causing a step-change in operating performance of at least one of the humidifier unit or the dehumidifier unit, monitor the measurement signal, and determine control parameter values for the control arrangement based on the measured air humidity within the space as a function of time subsequent to the step-change.
In some embodiments, the at least one humidity sensor is arranged to measure the air humidity in at least one of the first and second streams of air.
In some embodiments, the system further comprises a connection sensor, which is configured to sense a fluid connection state between the humidifier unit and the dehumidifier unit, and the control arrangement is operable to modify its operation in correspondence with the fluid connection state sensed by the connection sensor.
In some embodiments, the system further comprises at least one fluid connecting device between the humidifier unit and the dehumidifier unit, and the humidifier unit is configured to emit at least part of the third stream of air into the at least one fluid connecting device and the dehumidifier unit is configured to receive the first stream of air from the at least one fluid connecting device.
In some embodiments, the humidifier unit and the dehumidifier unit are combined into a unitary structure.
In some embodiments, the dehumidifier unit is configured to output a fourth stream of air which is generated when the first stream of air is processed for extraction of the liquid water, and the system further defines a fluid channel, which is configured to re-direct at least part of the fourth stream of air to an air inlet of the humidifier unit, to include said at least part of the fourth stream of air in the first stream of air.
In some embodiments, the fluid channel is arranged to redirect the fourth stream of air to the air inlet of the humidifier unit, so that the fourth stream of air forms the first stream of air.
In some embodiments, the system comprises a flow controller which is operable to set how much of the fourth stream of air that is re-directed to the air inlet of the humidifier unit.
In some embodiments, the system is switchable, by operation of the flow controller, between a first operating mode and a second operating mode, wherein the system, in first operating mode, is configured to admit surrounding air into the second stream of air and provide at least part of a fourth stream of air into the surrounding air, and wherein the system, in the second operating mode, is configured to direct the fourth stream of air to the air inlet of the humidifier unit, so that the fourth stream of air forms the first stream of air.
In some embodiments, the system, in the first operating mode, is configured to provide all of the fourth stream of air into the surrounding air.
In some embodiments, the system comprises an inlet line, which is connected to the air inlet of the humidifier unit, and an outlet line, which is connected to an outlet of the dehumidifier unit to receive the fourth stream of air from the dehumidifier unit, wherein the fluid channel is fluidly connected at a first junction on the outlet line and at a second junction on said the inlet line, and wherein the flow controller is arranged to control an air flow rate through the fluid channel from the outlet line to the inlet line.
In some embodiments, the humidifier unit is configured to emit the third stream of air into surrounding air, and the dehumidifier unit is configured to receive the first stream of air from the surrounding air.
In some embodiments, the humidifier unit is physically separated from the dehumidifier unit.
In some embodiments, the humidifier unit is configured to receive tap water and process the tap water to generate the third stream of air from the second stream of air and the tap water.
In some embodiments, the humidifier unit is connected to receive the tap water from a tank, wherein the system is configured to estimate a time point of depletion of the tank, based on a signal from a level sensor of the tank or based on measured air humidity within a space that comprises the humidifier unit and the dehumidifier unit, and output, in advance of said time point, a user instruction to add tap water to the tank.
In some embodiments, the system is configured to estimate the time point of depletion by use of a calculation model, which is configured to predict the extraction of the liquid water as a function of air humidity, and by further use of data indicative of consumption of the treatment fluid by an operating therapy system, which is connected to receive the treatment fluid from the system.
In some embodiments, the system further comprises a storage unit, which is arranged to receive and accumulate the liquid water from the dehumidifier unit or the treatment fluid from the fluid generation unit.
A second aspect is a method of providing treatment fluid for use in dialysis therapy. The method comprises: processing a first stream of air for extraction of liquid water; generating the treatment fluid by mixing at least part of the liquid water with one or more substances; processing a second stream of air to generate a third stream of air with increased humidity compared to the second stream of air; and including at least part of the third stream of air in the first stream of air.
A third aspect is a computer-implemented method of operating the system of the first aspect or any of its embodiments. The method comprises: receiving at least one measurement signal representing the air humidity within a space that comprises the humidifier unit and the dehumidifier unit, and jointly operating the humidifier unit and dehumidifier unit to achieve a predefined air humidity within the space as indicated by the at least one measurement signal.
The embodiments of the first aspect may be adapted as embodiments of the second or third aspect.
A fourth aspect is a computer-readable medium comprising program instructions, which when executed by a processor causes the processor to perform the method of the second or third aspect, or any embodiment thereof. The computer-readable medium may be a non-transitory medium or a propagating signal.
Still other objectives, aspects, embodiments and technical effects, as well as features and advantages may appear from the following detailed description, from the attached claims as well as from the drawings.
Embodiments will now be described in more detail with reference to the accompanying and schematic drawings.
Embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments are shown. Indeed, the subject of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure may satisfy applicable legal requirements.
Also, it will be understood that, where possible, any of the advantages, features, functions, devices, and/or operational aspects of any of the embodiments described and/or contemplated herein may be included in any of the other embodiments described and/or contemplated herein, and/or vice versa. In addition, where possible, any terms expressed in the singular form herein are meant to also include the plural form and/or vice versa, unless explicitly stated otherwise. As used herein, “at least one” shall mean “one or more” and these phrases are intended to be interchangeable. Accordingly, the terms “a” and/or “an” shall mean “at least one” or “one or more”, even though the phrase “one or more” or “at least one” is also used herein. As used herein, except where the context requires otherwise owing to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, that is, to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments.
As used herein, the terms “multiple”, “plural” and “plurality” are intended to imply provision of two or more elements, whereas the term a “set” of elements is intended to imply a provision of one or more elements. The term “and/or” includes any and all combinations of one or more of the associated listed elements.
It will furthermore be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing the scope of the present disclosure.
Well-known functions or constructions may not be described in detail for brevity and/or clarity. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
As used herein, “dialysis therapy” refers to any therapy that replaces or supplements the renal function of a patient by use of treatment fluid. Dialysis therapy includes, without limitation, extracorporeal blood therapy and peritoneal dialysis therapy.
As used herein, “treatment fluid” refers to any fluid that is consumed as a result of dialysis therapy. Treatment fluid includes, without limitation, dialysis fluid, replacement fluid and substitution fluid.
As used herein, “ambient air” or “open air” refers to air located within a confined space, such as an apartment, a room, or the like but outside of the system described herein. When referring to an air stream being received from the surroundings, the air stream is taken from ambient air. Similarly, when referring to an air stream being emitted into the surroundings, the air stream is included in ambient air.
Like reference signs refer to like elements throughout.
The present disclosure relates to a technique of generating treatment fluid for a dialysis system. The technique is applicable to both peritoneal dialysis (PD) therapy or extracorporeal (EC) blood therapy. For context only, fluid generation in relation to PD therapy and EC blood therapy will be briefly discussed with reference to
In the example of
The partitioning into an FPS 20 and a therapy system 10 is arbitrary and made only for explanatory purposes.
In some embodiments, TF for use in EC blood therapy on patients with chronic kidney disease (CKG) is generated by mixing a single concentrate with water at a dilution ratio of 10-50 by volume. In a non-limiting example, the single concentrate comprises lactate, sodium, potassium, calcium, magnesium, glucose and chloride. Such a concentrate is, for example, commercially available for the PureFlow SL system from NxStage. Alternatively, TF may be generated by mixing two concentrates with water. For example, a base concentrate and an acid concentrate may be mixed with water at a dilution ratio of 10-50. Such concentrates are commercially available and well-known in the art. In a non-limiting example, the base concentrate comprises a buffer, for example bicarbonate, and the acid concentrate comprises sodium, potassium, calcium, magnesium, glucose, acetate and chloride. In some acid concentrates, acetate is replaced or supplemented by another acid, for example citric acid. In some embodiments, TF for CRRT treatment of patients with acute kidney injury (AKI) is generated by mixing at least one concentrate with water. In a non-limiting example, such a dialysis/replacement fluid comprises bicarbonate, sodium, potassium, calcium, magnesium, phosphate, glucose, acetate and chloride. In one example, a base concentrate and an electrolyte concentrate may be mixed with water to form the dialysis/replacement fluid. For example, the base concentrate may be an alkaline hydrogen carbonate solution, and the electrolyte concentrate may be an acidic glucose-based electrolyte solution.
TF for use in PD therapy may be generated by mixing at least one concentrate with water. Example compositions of concentrates to be mixed with water are disclosed in US2018/0021501 and WO2017/193069, which are incorporated herein by reference. In one example, the one or more concentrates comprises ions and/or salts, such as lactate, acetate, citrate, bicarbonate, KCl, MgCL2, CaCl2, NaCl, and an osmotic agent. In any of the embodiments described herein, the osmotic agent may be, or include, glucose (or polyglucose), L-carnitine, glycerol, icodextrin, or any other suitable agent. For example, icodextrin is a glucose polymer preparation commonly used as osmotic agent in PD fluids. Alternative osmotic agents may be fructose, sorbitol, mannitol and xylitol. It is noted that glucose is also sometimes named as dextrose in the PD field. The term glucose is herewith intended to comprise dextrose.
In some embodiments, the water extraction unit 210 is instead configured to extract EW by use of a desiccant. In these embodiments, box 220A represents the desiccant. The desiccant is a hygroscopic substance which is arranged to interact with DIA. During this interaction, the desiccant adsorbs and/or adsorbs water molecules that are present in DIA. The water extraction unit 220 is configured to process the desiccant 220A to release the water molecules, for example by one or more of heating, moisture vapor pressure change, or UV irradiation. The released water molecules are then collected to form EW. This type of water extraction is effective also when the incoming air has a low relative humidity, such as down to 20%, or even lower. Generally, the quality of EW obtained by this technique is dependent on the desiccant, in particular its selectivity towards water.
The DHU 22 in
Table 1 below shows the required air flow rate, for a given Hdi, to extract 11.1 ml/min of EW, resulting in 16 liters per 24 hours, which corresponds the typical daily consumption in PD therapy. Table 1 also shows the resulting Hdo. As seen in Table 1, the required air flow may become high if Hdi is low and/or if Hdo is to be relatively high. Thus, in certain situations, the DHU 22 may be unable to achieve the target value(s). These situations are mitigated by the provision of the HU 21 and by joint control of the HU 21 and the DHU 22. For example, the HU 21 may be operated to increase Hdi by increasing Hho.
Reverting to
By the gaseous transportation, the DHU 22 is able to increase its EW production even if the available volume of air is limited, for example when the DHU 22 is located indoors and only operates on indoor air. In the following, the confined space where the HU 21 and DHU 22 are located is generally referred to as “premises” and may be in the home of a patient or in a clinic. The water vapor content of ordinary indoor air is typically 4-15 g per m3 of air for temperatures of 20-25° C. and relative humidity (RH) of 30-70%. Even if the DHU 22 is located in a premises with a high turnover of air, for example through a ventilation system, it may be difficult to provide the required air volume for EW production if the size of the premises is limited. For example, an apartment of 80 m2 would require a turnover frequency of about 12 per day to provide a total air volume of 2400 m3. Table 2 below shows the required air volume to extract 16 kg of liquid water for a given air humidity (RH start) at the start of the extraction process. Table 2 also shows the final air humidity (RH end) after the extraction process. As seen in Table 2, the humidity of the indoor air may become undesirably low in order to meet the required air volume, even if the turnover frequency is as high as 12 per day. It is also likely that RH end is even lower, if possible, near the DHU 22. A dry indoor climate may be perceived as unpleasant or even cause or worsen respiratory ailments, as well as cause a sore throat, irritated eyes, dehydration, dry skin, etc. Generally, it may be desirable for the relative humidity in a premises to be in the range of 30-70% or 40-60% for health and comfort.
It may also be noted that EC blood therapy generally requires much larger amounts of dialysis fluid. The required air volume to be processed by the DHU 22 for extraction of EW is correspondingly larger.
The HU 21 and the DHU 22 may be arranged in various configurations to perform the gaseous transportation of tap water. Examples of such configurations are described further below. Typically, all configurations are operable to maintain an acceptable humidity in the premises of the HU 21 and the DHU 22.
Additional technical advantages may also be attained by proper design of the DHU 22. If the DHU 22 is configured to extract EW from a desiccant, it is possible to achieve an inherent purification of EW by use of a desiccant that has a high selectivity towards water. The high selectively implies that the desiccant is tailored to adsorb and/or absorb water molecules rather than other molecules that may be present in DIA. The inherent purification by the DHU 22 may reduce, or even eliminate, the need to process the extracted water by conventional water purification to ensure that TF fulfils regulatory requirements or standards, for example, water for dialysis according to ISO 23500-3. Conventional water purification typically involves Reverse Osmosis (RO), which is quite costly.
In some embodiments, the water extraction unit 220 is configured to produce EW that has conductivity of less than 10 μS/cm, and preferably less than 5 μS/cm or 1 μS/cm. As understood from the foregoing, this may be achieved by using a desiccant with a high selectivity of water.
In some embodiments, the desiccant is an ionic or covalent porous solid, including but not limited to metal-organic and organic porous framework materials, zeolites, organic ionic solids, inorganic ionic solids, organic molecular solids, or inorganic molecular solids, or any combination thereof. The desiccant may be used in a pure, single-phase form, as a composition of different active chemical materials, and/or in combination with performance enhancing additives modulating its properties. Performance enhancing additives may include materials with a high thermal conductivity and molar water absorptivity. The active chemical compound may be used in the form of a powders, extrudates, molded bodies, pressed pellets, pure or composite films, or sintered bodies. In some embodiments, the water capture material comprises an active chemical compound, such as a metal-organic framework (MOF). MOFs are porous materials that have repeating secondary building units (SBUs) connected to organic ligands. In some variations, the SBUs may include one or more metals or metal-containing complexes. In other variations, the organic ligands have acid and/or amine functional group(s). In certain variations, the organic ligands have carboxylic acid groups. Any MOF capable of adsorbing and desorbing water may be employed in the systems provided herein. In some embodiments, MOF-303 is used as desiccant, MOF-303 has a structure of Al(OH)(HPDC), where HPDC stands for 1H-pyrazole-3,5-dicarboxylate. Other conceivable MOFs for use as desiccant include, for example, MOF-801, MOF-841 and MIL-160. A combination of MOFs may also be used as desiccant. Further examples and implementation details are found in the articles “Metal-Organic Frameworks for Water Harvesting from Air”, by Kalmutzki et al., published in Adv. Mater. 2018, 30, 1704304, and “Practical water production from desert air”, by Fathieh et al., published in Sci. Adv. 2018, Vol. 8, Issue 6, which are incorporated herein by reference.
The non-connected embodiment relies on water vapor transport between the HU 21 and the DHU 22, meaning that humid air produced at the HU 21 is transported to the DHU 22 by convection (natural and/or forced) and/or by mixing. This “wireless water transport” between the HU 21 and the DHU 22 through the premises may be more or less effective depending on the transport bandwidth (or, conversely, the flow resistance) between the HU 21 and the DHU 22. The transport bandwidth is dependent on, for example, the distance between the HU 21 and the DHU 22, the ventilation characteristics of the premises, and the presence of obstacles or obstructions such as doors and furniture.
Examples of different installations are shown in
In a first installation example, the HU 21 is placed in the bathroom 41 in fluid connection with a permanent water supply at the sink 21. As long as the door 44 between the bathroom 41 and the bedroom 45 is open, moisture generated by the HU 21 will over time propagate to the DHU 22, for example driven by forced convection. The forced convection may be caused by the pumping device 213 in the HU 21, the pumping device 223 in the DHU 22, or by a separate fan, a ventilation system, etc. In a second installation example, the HU 21 is placed in the down-left corner of the bedroom 45 to be out of the way. The HU 21 may receive tap water from a tank 30, as shown, or through a tubing connected to the water supply in the bathroom 41. When using a tank 30, it may be advantageous for the DHU 22 to be configured to extract more water from the surrounding air than is added by the HU 21. This will reduce the need for tap water and thereby reduce the need for the user to carry tap water from the bathroom 41 to the bedroom 42. In a third installation example, the HU 21 is located close to the DHU 22. Like in the second installation example, the HU 21 may receive tap water from a tank 30, as shown, or through a tubing connected to the water supply in the bathroom 41.
In some embodiments, the non-connected embodiment as shown in
The sensor data may be transmitted to the control device 25 by wire or wirelessly. Likewise, the set point data SP1, SP2 may be transmitted by wire or wirelessly to the HU 21 and the DHU 22. The control device 25 may be a separate device, as shown, or may be included one of the local control units 219, 229. Thus, generally, the functionality of the local control units 219, 229 and the control device 25 may be performed by a control arrangement that may be centralized or distributed in any way.
In step 308, the control arrangement performs a step-response test. The step-response test is performed for the purpose of configuring the control arrangement in relation to the premises. For example, the step-response test may serve to improve the ability of the control arrangement to maintain a suitable humidity within the premises and/or to ensure that sufficient amount of water vapor is received by the DHU 22. Step 308 may be automatically performed whenever the HU 21 and/or DHU 22 is started, or at a predefined time interval, or when an error condition is detected by the control arrangement, for example based on measured humidity. For example, step 308 may be performed when the measured humidity changes in a way that is not expected. Alternatively or additionally, step 308 may be performed on command by the user, for example by the user pressing a dedicated button on the HU 21 or the DHU 22. Alternatively or additionally, the step 308 may be automatically performed to verify input data entered by the user, for example regarding the type or size of the premises.
In the step-response test, the control arrangement causes a step-change in the operating performance of the HU 21, for example in terms of the production rate of water vapor by the HU 21, and/or in the performance of the DHU 22, for example in terms of the consumption rate of water vapor by the DHU 22. In a non-limiting example, the HU 21 may be operated to increase/decrease the flow rate of HOA, and/or to increase/decrease the humidity of HOA. In another non-limiting example, the DHU 22 may be operated to increase/decrease the extraction rate of EW. Generally, the step-change may be generated by changing the operating point of the HU 21 and/or the DHU 22, or by starting/stopping the HU 21 and/or DHU 22. After the step-change, the control arrangement monitors sensor data representative of the humidity in the premises over time. For example, the sensor data may represent one or more of Hdi, Hhi, Ha (
In step 310, the user may input further control data to the control arrangement, including a set point (target value) for the EW production rate by the DHU 22, and optionally a total amount of EW (“total EW amount”) to be extracted by the DHU 22 for a given operating period. Alternatively, the control data may be retrieved by the control arrangement from a memory unit in the dialysis system, for example in the therapy system 10, the FGU 24, the HU 21 or the DHU 22. In step 311, the control arrangement operates the HU 21 by use of the control parameter values from step 309, to achieve the humidity set point (entered in step 307). In step 312, the control arrangement operates the DHU 22 by use of the control parameter values from step 309, to achieve the humidity set point and/or to achieve the set point for the EW production rate (entered in step 310). It may be noted that HU 21 and DHU 22 may be jointly operated towards plural humidity set points, given by different humidity sensors. It is also conceivable that HU 21 and DHU 22 are separately operated towards different humidity set points, given by different humidity sensors. It should also be understood that, for a time period after start-up of the HU 12 and the DHU 22, humidity will be unevenly distributed between the HU 21 and the DHU 22 until a steady-state condition is reached.
In step 313, the HU 21 and the DHU 22 are stopped when an accumulated amount of EW exceeds a threshold value, which may be the total EW amount entered in step 310 or a predefined value. The accumulated EW amount may be determined in any suitable way, such as by flow measurement, volumetric metering, etc. for example by the flow controller 228 (
It is conceivable that at least one of the HU 21 and the DHU 22 comprises a positioning device, which is configured to generate position data indicative of the relative positioning of the HU 21 and the DHU 22. The relative positioning may supplement or replace the step-response test (step 308) and be used to estimate the transport bandwidth between the HU 21 and the DHU 22 and/or to determine the control parameters (step 309). In one example, the positioning device is configured to measure the distance between the HU 21 and the DHU 22, by any conceivable technique. If data is exchanged wirelessly between the HU 21 and the DHU 22, the distance may be estimated based on signal strength. In other examples, more advanced positioning is used, for example by connecting the HU 21 and the DHU 22 to an indoor positioning system. In a further alternative, the user may input the distance via the interface device, for use by the control arrangement.
Except for the FCD 21′, the example in
The provision of HOA2 may improve the ability of the control arrangement to control the relative humidity in ambient air within the premises. The control arrangement may control the outlet humidity Hdo of DOA and/or the outlet humidity of HOA2 to attain a target humidity in the premises, as given by Hdi from sensor 224 (
The example in
As shown in
The method 300 in
The system in
The example in
Compared to other variants, the closed recirculation system maximizes the humidity differences over the HU 21 and DHU 22 and thereby minimizes the air flow rate through them. This also enables downsizing of the system.
Another potential advantage of the closed recirculation system, which repeatedly humidifies and dehumidifies the same air, is that volatile contaminants initially present in the air will be removed early in the process if the water extraction unit 220 (
It may be noted that the closed recirculation system in
In some embodiments, the system is configured to be switched, manually or by the control arrangement, between operating modes corresponding to two or more of the configurations in
The flow controller 29A, 29B is operable to control the flow rate of RA through the FCD 21″, and thus the recirculation fraction. The flow controller 29A, 29B may include any number of valves of any type, one or more pumps, one or more flow restrictors, etc.
The system in
The flow controller 29A, 29B may be operated to set the recirculation fraction to any value from 0% (open mode without recirculation) to 100% (closed mode). In some embodiments, the recirculation fraction may be set to one or more predefined values between 0% and 100% to operate the system in the open mode with recirculation. Alternatively, the recirculation fraction may be changed continuously by the valve arrangement 29A, 29B between 0% and 100%, or in any other range. In some embodiments, the system is switched between the closed mode and one of the open modes, for example the open mode without recirculation. This corresponds to toggling the flow controller 29A; 29B between a recirculation fraction of 0% and a recirculation fraction of 100%.
The closed mode may be selected to minimize the required air flow rate and/or to avoid affecting the ambient air in the premises. On the other hand, the open modes enable air exchange with the environment and offer an opportunity of decreasing the tap water demand by extracting a fraction of the water from the environment instead of from vaporized tap water. Furthermore, the open modes enable control of the air humidity in the premises.
Another reason for switching between operating modes may be to reduce the noise of the system. The closed mode is likely to be more silent than the open modes and may thus be used during night, whereas an open mode may be used during the day, for example to also extract water from the environment.
Although not shown in
It is conceivable that the HU 21 and the DHU 22 are configured as modules that may be structurally combined to form a non-connected embodiment or a connected embodiment of any type. Such a modular system may comprise a connection sensor, which is configured to sense a fluid connection state between the HU 21 and the DHU 22. The control arrangement may be responsive to the fluid connection state indicated by the connection sensor and modify its operation accordingly. Depending on fluid connection state, the control arrangement may select different operating parameters and/or selectively include or exclude operation steps. Some non-limiting examples of the use of connection sensors are shown in
In a variant of the non-connected embodiment (
It is conceivable to connect the HU 21 to receive HIA from outdoor air and/or to connect the DHU 22 to provide DOA to outdoor air. This reduces the impact of the system on the humidity within the premises. It may also reduce the required capacity of the HU 21.
Reverting to the installation examples in
It should be understood that the control arrangement may operate on either relative humidity or absolute humidity. For example, by also measuring temperature, a measured relative humidity may be converted into an absolute humidity.
While the subject of the present disclosure has been described in connection with what is presently considered to be the most practical embodiments, it is to be understood that the subject of the present disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the appended claims.
Further, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2151585-3 | Dec 2021 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086926 | 12/20/2022 | WO |
