TECHNICAL FIELD

The presently disclosed subject matter relates to the field of liquid pumping technology and, more particularly, but not exclusively, to airlift pumps.

BACKGROUND

Agricultural fields or remote communities, located where no regular power supply is available, must rely on manual labor, generators, or photovoltaic panels, to power water-well pumping equipment. This type of equipment can be expensive to purchase and maintain, and often requires application of significant power to pump liquids from deep underground reservoirs. Moreover, when installed in a well head, electrical pumps often require a secondary, backup hand-pump for events of electrical power outages, or in case of malfunction. On the other hand, hand pumps are limited to manual labor and mostly cannot operate autonomously using solar or electrical power.

An airlift, or specifically a “Geyser” type pump, can be used for pumping with no moving parts, driven by a compressed air source, though it requires a large air flow as input, supplied by mechanical blowers. A typical airlift pump consists of an open- ended vertical riser tube, partially submerged in a liquid reservoir/well, and utilizes compressed air (or another gas) injected near the bottom end of the vertical riser tube. Once the compressed air (or other gas) is injected into the liquid, the average density of the air-liquid mixture in the riser tube becomes less than the density of the surrounding liquid. The resulting buoyant force causes a pumping action in the riser tube and the air-liquid mixture is discharged at the top of the riser tube. This solution is less efficient and reliable than using a mechanical liquid/water pump and is more often used when the pumped fluid contains a large amount of solids.

A recent device known as “impact pump”, has no moving parts, and can be inserted into a well, and powered by a surface water-pump. The impact pump is a “range extender” that uses the Joukowski effect to enable most surface pumps to access deep water without sliding seals or electronics below ground surface. However, this type of pumps can draw water from a maximal depth of 7 meters. In cases where groundwater is located beyond suction depth (e.g., deeper than 7 meters), submersible pumps may be required, which push water up to ground surface from underground reservoirs. This typically involves situating motors and serviceable parts below the waterline, often in confined conditions. The efficiency of such solution is limited by small rotor and impeller diameters, and failures are common, due to dry running (causing motor burnouts), and damage caused by silt and grit. Maintenance of such systems typically involves removing the pump from the well, which is often arduous and difficult, particularly where hard pipes are used.

Electric surface pumps can also be used to pump liquids from underground reservoirs, but they still suffer from the same drawbacks described hereinabove.

Other solutions may utilize simple suction and lift hand pumps, but these types of pumps are prone to malfunctions, and cannot pump from underground reservoirs that are deeper than 7 meters, and they are of course limited to manual operation only.

GENERAL DESCRIPTION

There is a need in the art for an improved pumping system and technique allowing simple and efficient lifting / raising of liquid quantities, such as water, from various types of bodies-of-liquids, such as deep underground liquid reservoirs (e.g., well liquids) and/or streams, and from surface liquid reservoirs and/or streams as well. The present disclosure provides a pumping system that can be easily installed for direct contact with a body-of-liquid of deep underground liquid reservoirs/well, for repeated lifting of liquid quantities from increased depths (e.g., deeper than 7 meters), by (e.g., above-ground) application of gas-fluid pressure e.g., pressurized gaseous material such as air. It is noted that the embodiments disclosed herein can be used for pumping from liquid reservoirs or streams located above ground surface and under the ground surface.

The pumping system hereof is configured to receive and accumulate gas-fluid (e.g., air) pressure in a pressure storage unit thereof, which can be located either at least partially under the ground surface or above ground surface, and to communicate the gas-fluid pressure accumulated in the pressure storage unit to a pumping unit thereof, which bottom portion is immersed in the body-of-liquid to be pumped from. An immersed-end portion of the pumping unit, having a bottom opening, is immersed in the body-of-liquid, and an upper-end portion thereof, having a liquid outlet, is located above the liquid level of the body-of-liquid, preferably above the ground surface, to discharge the liquid quantities thereby pumped. The pumping unit is configured to define surge pressure conditions communicated thereto from the pressure storage unit that can lift a certain quantity of liquid from the body-of-liquid along the pumping unit, and discharge it therefrom via the liquid outlet in its upper-end portion.

Optionally, but in some embodiments preferably, the gas-fluid pressure supplied to the pumping system comprises pressurized gas (e.g., ambient air), provided thereto by an external source. In possible embodiments the gas-fluid pressure is supplied to the pumping system is in a form of pressurized gas pulses received from an acoustic wave source, such as a thermoacoustic heat engine/compressor (or any type of blower or compressor), for temporally accumulating pressurized gas conditions thereinside. It is however noted that any other type of gas-fluid pressure and/or acoustic wave source can be similarly used to operate the pumping system disclosed herein.

The pressure storage unit comprises in some embodiments an intermediate container/tank and an inverted-cup structure (also referred to herein as pressure chamber) fixedly mounted inside the intermediate container/tank. In some embodiments, the pumping system utilizes an auxiliary working liquid (e.g., water or any other liquid) contained inside the intermediate container/tank, for storing fluid pressure/potential energy thereinside expressed by variable liquid levels of the auxiliary working liquid inside the intermediate container/tank.

The inverted-cup structure is immersed in the auxiliary working liquid contained in the intermediate container/tank, and at least partially filled with the auxiliary working liquid. The gas-fluid pressure (e.g., acoustic pulses/waves) supplied to the pumping system is introduced into an upper portion of the inverted-cup structure, thereby downwardly pushing quantities of the auxiliary working liquid contained inside the inverted-cup structure out of it (e.g., or pulling them upwardly thereinto), via its opening. This way, as gas-fluid pressure is supplied to the pumping system, portions of the auxiliary working liquid are expelled out of the inverted-cup structure into the intermediate container/tank, thereby increasing the level of the auxiliary working liquid inside the intermediate container/tank and accumulating pressurized gas in the upper portion of the inverted-cup structure.

The pumping unit comprises an internal liquid passage extending upwardly a certain length from the bottom opening of the pumping unit, a discharge tube (e.g., siphon) configured with the liquid outlet in an upper portion thereof and at least partially accommodating by a bottom potion thereof a portion of the internal liquid passage, a gas-liquid (e.g. , cylindrical) vessel configured to receive via an upper portion thereof pressurized gas from the pressure storage unit and to transfer surges of the pressurized gas via a bottom portion thereof into the bottom end portion of the discharge tube, for pushing quantities of the liquid along the discharge tube towards the liquid outlet. For example, the surges of the pressurized gas affect in possible embodiments liquid pumping buoyance forces inside the discharge tube for propelling the liquid thereinside towards the liquid outlet.

In some embodiments the pumping unit comprises a liquid pushing (e.g., sphere) member disposed inside the discharge tube and configured to move therealong in response to the pressure surges from the gas-liquid vessel, and propel quantities of the liquid along and out of the discharge tube. The discharge tube extends all the way up to place the liquid outlet of the pumping unit out of the body-of-liquid (e.g., above ground surface). The liquid pushing member is configured to rest above a top opening of the internal liquid passage immersed in liquid of the body-of-liquid, and to push liquid quantities thereof along the discharge tube responsive to the pressure surges from the gas-liquid vessel for discharge through the liquid outlet.

The pressurized gas directed to the upper portion of the gas-liquid vessel propagates towards a bottom portion thereof against a quantity of liquid contained inside the pumping unit, as the pressure accumulated inside the inverted cup structure increases, wherefrom it is released upwardly into the discharge tube as a surge / burst of pressurized gas to push quantities of liquid along the discharge towards and out of the liquid outlet. In embodiments utilizing a liquid pushing member inside the discharge tube, the surge/burst of pressurized gas push upwardly the liquid pushing member along the discharge tube with a portion of the liquid contained inside the discharge tube towards and out of the liquid outlet.

After the portion of liquid is discharged via the liquid outlet of the pumping unit, the liquid level inside the pumping unit levels with the liquid level of the body-of- liquid, and the pumping system recycles and returns to its initial state. If a liquid pushing member is used inside the discharge tube, after the portion of liquid is discharged via the liquid outlet of the pumping unit the liquid pushing member falls downwardly along the discharge tube and arrests over the top opening of the internal liquid passage immersed in a quantity of the liquid leveled inside the discharge tube. As such, the pumping system hereof (with or without the liquid pushing member) is configured for iterative/periodic pumping of liquid quantities from the body-of-liquid in which its bottom portion is submerged.

The pressure storage unit can be located at, below, or above, ground surface, while the pumping unit may be installed in an underground / subsurface liquid reservoir. In possible embodiments the gas-fluid pressure is provided to the pressure storage unit in form of acoustic pulses e.g., generated by a thermoacoustic compressor powered by a heat source, such as the sun, but any other possible gas-fluid pressure sources can be similarly used. It is understood that embodiments of the pumping system hereof may be useful for pumping liquid out of liquid reservoirs/streams via narrow access passages e.g., well water, aquifer water, subsea well, and suchlike.

In some embodiments, the gas-liquid vessel of the pumping unit is a type of peripheral (e.g., cylindrical) vessel, and its discharge tube can be a type of siphon having a bottom portion passing inside the peripheral vessel. A top portion of the peripheral vessel is similarly fluidly coupled to the pressure storage unit for receiving the pressurized gas therefrom. In possible embodiments the internal liquid passage can be formed inside the peripheral vessel by a central conduit projecting upwardly from a base of the peripheral vessel into the bottom portion of the discharge tube/siphon. The central conduit this way allows passage of liquid between the liquid reservoir, the peripheral vessel, and the discharge tube/siphon of the pumping unit.

The discharge tube/siphon extends in some embodiments out of the liquid reservoir to a certain predefined height to which the liquid (e.g., water) is to be raised.

In some embodiments, the discharge tube/siphon and the peripheral vessel define a fluid flow path therebetween including an outer circumferential chamber formed around a bottom portion the discharge tube/siphon within the peripheral vessel, and an inner circumferential chamber formed around the internal liquid passage (e.g., the central conduit) within the discharge tube/siphon.

In some embodiments the gas-liquid vessel defines a fluid flow path having a J- shaped bottom portion turning upwardly into the bottom portion of the discharge tube/siphon. This way, when the pressurized gas from the pressure storage unit reaches the upward turn of the J-shaped fluid path and the required surge pressure conditions are reached, a surge of pressurized gas is released upwardly into the discharge tube/siphon to propel a quantity of the liquid inside the discharge tube towards and our of the liquid outlet. Similarly, if a liquid pushing member is provided inside the discharge tube, the surge of pressurized gas is released upwardly via the J-shaped fluid path towards the liquid pushing member, to thereby propel it upwardly thereinside. The upward movement of the liquid pushing member elevates a quantity of the liquid inside the discharge tube/siphon towards and out of the liquid outlet of the discharge tube/siphon.

In one aspect there is provided a pump system comprising a pressure storage unit configured for receiving input pressure for build-up and storage of pressurized gaseous material thereinside, and a pumping unit at least partially submerged in a body- of-liquid and configured for receiving the pressurized gaseous material from the pressure storage unit. The pumping unit comprises an internal liquid passage extending upwardly a certain length from a bottom opening thereof, a discharge tube (e.g., forming a siphon) at least partially accommodating by a bottom end potion thereof a portion of the internal liquid passage, a gas-liquid vessel in fluid communication with the discharge conduit and configured to receive via an upper portion thereof pressurized gaseous material from the pressure storage unit, to thereby lift a certain amount of liquid towards a liquid outlet of the discharge tube.

Optionally, but in some embodiment preferably, the pump system comprises a liquid pushing member disposed inside the discharge tube and configured to move therealong in response to surges of the pressurized gaseous material from the gas-liquid vessel. The pressure storage unit can be located at or above ground surface.

In possible embodiments the pressure storage unit is at least partially filled with an auxiliary working liquid. The pressure storage unit comprises in some applications an intermediate liquid tank and a pressure chamber thereinside at least partially filled with the auxiliary working liquid. The pressure chamber can be fluidly coupled to an external gas-fluid pressure source for receiving the input pressure for the build-up of the pressurized gaseous material thereinside.

The pressure chamber is fluidly coupled in some embodiments to the pumping unit for relaying the pressurized gaseous material thereto. An opening of the pressure chamber can be suspended over a base surface of the intermediate liquid tank so as to allow flow of the auxiliary working liquid therebetween. The pressure storage unit is configured possible applications to cause difference between auxiliary working liquid levels in the intermediate liquid tank and the pressure chamber during receipt of the input pressure.

The gas-liquid vessel can be configured to define a peripheral outer camber about a portion of the discharge tube. The peripheral outer chamber is fluidly coupled in possible embodiments to the pressure chamber for receiving the pressurized gaseous material therefrom. The pump system can be configured to define an internal peripheral chamber between the discharge tube and the internal liquid passage for enabling passage of liquid between the body-of-liquid and the gas-liquid vessel. In some embodiments the gas-liquid vessel is configured to form a J-shaped passage extending into the discharge tube.

In a variant, the discharge tube comprises a stopper element configured to stop movement of the liquid pushing member thereinside.

The pump can comprise a thermoacoustic resonator configured to supply the input pressure. The thermoacoustic resonator is operated in some embodiments by solar radiation. The thermoacoustic resonator may comprise a coned resonator tube. Optionally, inner walls of a resonator tube of the thermoacoustic resonator are coated with one or more reflective materials. The thermoacoustic resonator comprises in some embodiments a solid porous structure and an ambient heat exchanger.

In another aspect there is provided a method of pumping liquid from a body-of- liquid. The method comprises transferring input pressure to a pressure storage unit to thereby accumulate pressurized gas thereinside, communicating the pressurized gas to a gas-fluid vessel at least partially submerged in the body-of-liquid, introducing surges of the pressurized gas from the gas-fluid vessel into a discharge tube for thereby propelling quantities of the liquid of the body-of-liquid contained inside the discharge tube therealong. The method comprises in some embodiments propelling a liquid pushing member disposed along the discharge tube in response to the surges of the pressurized gas.

The method can comprise placing the pressure storage unit at or above ground surface. In some embodiments the method comprises manipulating an auxiliary working liquid inside the pressure storage unit responsive to the input pressure. The method can comprise moving quantities of the auxiliary working liquid between an intermediate liquid tank and a pressure chamber of the pressure storage unit responsive to the input pressure for accumulating the pressurized gas inside the pressure chamber.

The method comprises in some embodiments coupling the pressure storage unit to a thermoacoustic resonator configured to supply the input pressure. BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings. Features shown in the drawings are meant to be illustrative of only some embodiments of the invention, unless otherwise implicitly indicated. In the drawings like reference numerals are used to indicate corresponding parts, and in which:

Fig. 1 is a schematic illustration of an exemplary setup of a pump system driven by a thermoacoustic compressor/engine, in accordance with the presently disclosed subject matter;

Fig. 2A is a schematic illustration of a general layout of a thermoacoustic prime mover, in accordance with the presently disclosed subject matter;

Fig. 2B is a schematic illustration of an exemplary thermoacoustic prime mover coupled with an oscillating water column in two variations, in accordance with the presently disclosed subject matter;

Fig. 2C is a schematic illustration of an exemplary direct liquid/water pumping configuration comprising an oscillating water column, in accordance with the presently disclosed subject matter;

Fig. 2D is a schematic illustration of an exemplary thermoacoustic heat driven compressor having a coned resonator, in accordance with the presently disclosed subject matter;

Fig. 3A is a schematic illustration of an exemplary pump system comprising an intermediate water tank and a pressure chamber, in accordance with the presently disclosed subject matter;

Fig. 3B is a schematic illustration of another example for a submerged pumping unit illustrated in Fig. 3A;

Fig. 4 schematically illustrates pumping units implemented without a liquid pushing member according to some possible embodiments;

Figs. 5A to 5C are schematic illustrations of an exemplary pump cycle of the pump system, in accordance with the presently disclosed subject matter; and Figs 6A and 6B are graphic illustrations of efficiency simulation results obtained for the pump system of possible embodiments.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the presently disclosed subject matter. However, it will be understood by those skilled in the art that the presently disclosed subject matter may be practiced without these specific details. In other instances, well- known methods, procedures, and components have not been described in detail so as not to obscure the presently disclosed subject matter.

In the figures and descriptions set forth, identical reference numerals indicate those components that are common to different embodiments or configurations. Further, it will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity.

As used herein, the phrase "for example," "such as", "for instance" and variants thereof describe non-limiting embodiments of the presently disclosed subject matter. Reference in the specification to "one case", "some cases", "other cases" or variants thereof means that a particular feature, structure or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the presently disclosed subject matter. Thus, the appearance of the phrase "one case", "some cases", "other cases" or variants thereof does not necessarily refer to the same embodiment(s).

It is appreciated that, unless specifically stated otherwise, certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the presently disclosed subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

According to certain embodiments of the presently disclosed subject matter, there is provided a liquid/water pump, also referred to herein as a low pressure airlift (LPAL) pump, having a pumping unit (e.g., having a cylindrical body) that can be inserted into a body-of-liquid (e.g., water reservoir, such as a water well), and a secondary chamber (also referred to herein as intermediate container/tank e.g., an intermediate water tank, as further described hereinbelow) of a pressure storage unit, that in some cases can be installed above the ground surface. The pump system can be configured to pump water (or other liquid/fluid types) from deep body-of-liquids e.g., at depths greater than 7 meters. By way of non-limiting example, this can be achieved by providing a supply of gas-fluid pressure (e.g., compressed air) to the pump system, wherein the pumping depth thereof is not limited by the gas-fluid pressure levels supplied thereto.

Bearing this in mind, attention is drawn to Fig. 1, a schematic illustration of an exemplary field setup of a pump system 100 driven, in this non-limiting example, by a thermoacoustic compressor/engine 110, in accordance with the presently disclosed subject matter.

The pump system 100 (also referred to herein as “pump”) can be configured to operate e.g., on solar or other thermal energy source, while utilizing a thermoacoustic conversion cycle. The pump system 100 includes a thermoacoustic prime mover 10m that may be configured to enable at least two optional pumping methods as further described hereinbelow with reference to Fig. 2C and to Figs. 3 to 5. The pump system 100 can utilize a heat-driven thermoacoustic engine 110. In the thermoacoustic engine 110, solar (e.g., optically concentrated lOi) radiation lOh is absorbed as heat and converted into acoustic oscillations (i.e., air pressure waves) by means of a porous medium lOp located inside a close resonator tube 10. When fitted with an outlet check (one-way) valve lOv, such a resonator 10 draws air from the external environment e.g., at the heated prime mover 10m portion of the resonator 10 (e.g., via an inlet check valve and/or one or more apertures - not shown), and propagates air pressure waves therealong, which exit through the outlet check valve lOv when the pressure conditions threreat is positive.

A single thermoacoustic compressor/engine 10, when drawing ambient air from the surrounding environment, can only supply pressure as high as its oscillation amplitudes, which is typically too low for most practical uses. Nevertheless, low- pressure airlift (LPAL) pump systems of embodiments hereof are configured to store potential energy in a pressure storage unit 11, and use the low gas-fluid pressure supplied by a thermoacoustic compressor/engine 10 to pump liquid to elevated locations e.g., higher than the equivalent hydrostatic pressure . Exemplary methods described herein aim to improve the efficiency of such thermoacoustic-engine-based compressors, when connected to the (e.g., low-pressure airlift) pump system 100 of embodiments hereof. A first exemplary method hereof employs a long-coned resonator tube 10 e.g., close in length to the acoustic wavelength thereby generated. The cone-shaped resonator tube 10 concentrates the acoustic energy and thus increases the amplitude of the acoustic waves propagating thereinside. A second exemplary method hereof employs an oscillating water (or other liquid) column in a thermoacoustic engine 110, which reduces the working frequency, and thereby improves the outlet check valve lOv response.

In the non-limiting example of Fig. 1, the thermoacoustic compressor/engine 10 employed is at least partially under the ground surface, and configured to drive the whole pumping system 100, as further described hereinbelow. It is however noted that the same thermoacoustic compressor/engine 10 can be similarly mounted above the ground surface.

Referring to Fig. 2A, there is provided a schematic illustration of a general layout of a thermoacoustic prime mover 200 (also referred to herein as “prime mover”), in accordance with the presently disclosed subject matter. The prime mover 200 is typically confined in a hollow duct 210 of solid material. In some cases, where solar radiation is utilized, the inner walls of the duct 210 can be coated with one or more reflective materials while a transparent wall 220 may act as the end surface thereof. The duct 210 can further comprise a solid porous structure 230 (also referred to herein as “stack”), and/or an ambient heat exchanger 240.

In order to reduce the working temperature of thermoacoustic engine 110, a mass exchange technique can be added to the stack 230, as illustrated in Fig. 2B, thereby allowing constant contact between a condensed vapor (or an oscillating phasechanging vapor) and the stack 230. In this non-limiting example, an oscillating liquid column 250 is coupled to the prime mover 200, more particularly, but not exclusively, to the stack 230 and/or ambient heat exchanger 240 portion thereof. Fig. 2B illustrates two optional oscillating liquid column 250 configurations that can be utilized in accordance with the presently disclosed subject matter.

Particularly, in some embodiments the oscillating liquid column 250 is partitioned to define an inner column 255 and peripheral column 256 portions, having different cross-sectional areas and being in fluid communication, such that the acoustic pressure waves propagating thereinside due to the heat Q absorbed by the prime mover 200 affect respective different liquid levels 255e,256e in the respective columns 255,256 oscillating thereinside to alternatingly output gas-fluid pressure. Alternatively, in possible embodiments the U-shaped liquid column 257 has respective prime movers 200 coupled to each of its arms 258,259 for thereby absorbing heat Q and oscillating the liquid levels 258e,259e in its arms to alternatingly output the gas-fluid pressure. Gas/air is introduced into the oscillating liquid column 250 via an inlet check valve 251, and the gas-fluid pressure is outputted therefrom via an outlet check valve 252.

The various available forms of thermoacoustic power generation essentially convert the incoming heat flux Q into mechanical energy in the form of pressure oscillations/waves in the working gas/air inside a resonator. The thermoacoustic prime mover 200, with proper acoustic coupling, can be utilized to drive a liquid/water pump system 100 in at least two optional configurations, as further described hereinbelow.

First exemplary configuration(direct umping)

Referring to Fig. 2C, there is provided a schematic illustration of an exemplary direct liquid/water pumping configuration comprising an oscillating liquid/water column 250, optionally coupled to a thermoacoustic engine 200 or 250, in accordance with the presently disclosed subject matter.

As seen, a U-shaped oscillating water column 250 can be coupled to an acoustic energy source (e.g., thermoacoustic engine 200 or 250). The U section can be connected to a secondary water duct 260, which in turn can be connected to a pumping line 270 through a T-junction 280. The pumping line 270 comprises one or more check valves 290 located therealong. As the liquid/water levels 261e,262e in the respective arms 261,262 of the column 255 oscillates, some of the energy is transferred into the secondary liquid/water duct 260, wherein the oscillations of the liquid/water column 255 are eventually converted into one directional flow, enabled by the check valves 290, inside pumping line 270.

Particularly, in this non-limiting example, an "in" check valve 290 is used to draw liquid/water from the lower arm of the T-junction 280 when falling (suction) pressure conditions are present in the T-junction 280, and an "out" check valve 290 is used to draw liquid/water into the upper arm of the T-junction 280 when rising (propelling) pressure conditions are present thereon in the T-junction 280.

Second exemplary configuration(coupling to an airlift pump) According to certain embodiments of the presently disclosed subject matter, the acoustic duct may gradually converge. As seen in Fig. 2D, a resonator portion 310 of the thermoacoustic duct 300 has a coned shape. Such configuration of the thermoacoustic duct 300 of embodiments hereof, enables pressure amplitude increase or, in cases where the duct 300 is coupled to the U-shaped oscillating water column 255 (Fig. 2C), a working frequency decrease.

Referring to Figs 2B and 2D, in some cases, along the cone-shaped resonator 310 e.g., at low amplitude point(s), one or more small bores that allow air to enter the system, with or without inlet check clave(s). Additionally, the resonator 310 further comprises a small opening containing a check valve 320 and a pipe 322, located at a suitable location thereon. The check valve 320 and the pipe 322 may serve as thermoacoustic engine 110 pressure output (llOu in Fig. 1). This output is connectable in some embodiments to an input pipe / conduit 410 of a (e.g., low-pressure airlift - LPAL) pump system 400, illustrated in Fig. 3A.

Referring to Fig. 3A and 3B, schematically illustrating an (e.g., LPAL) pump system 400 configured for pumping liquid from a liquid reservoir 500 (e.g., subsurface / underground cavity, a deep well or a sump) according to some embodiments of the present disclosure. As shown in Fig. 3A, the pump system 400 is provided with a pressure storage unit 450p which can be disposed at, below, or above ground surface, and being in fluid communication with a pumping unit 450, at least a portion of which can be submerged within a liquid reservoir 500 (e.g., a water well) intended to be pumped, such that it is at least partially filled with the liquid 500q.

The pressure storing unit 450p is configured to receive gas-fluid (e.g., ambient air or low-pressure gas) input pressure, and to enables build-up of temporal pressure conditions (i.e., compressed /pressurized gas) thereinside, and communicate the pressurized gas to the pumping unit 450. To this end, the pressure storage unit 450p may be in fluid communication with an external pressure source, such as the thermoacoustic engine (110 in Fig. 1, 200 in Fig. 2B, 250 in Fig. 2C) for receiving the gas-fluid pressure therefrom via an input pipe / conduit 410. The pressure storage unit 450p is further configured for applying / relaying the temporal gas-fluid pressure conditions to the pumping unit 450. The temporal gas-fluid pressure conditions in the pumping unit 450 can facilitate elevation of liquid 500q contained inside a discharge tube 460 the pumping unit 450, towards and out of a liquid outlet 480t of the discharge tube 460. In some embodiments a liquid pushing member 490 is provided inside the discharge tube (e.g., siphon) 460, which is configured to push a quantity the liquid 500q towards and out of the liquid outlet 480t of the discharge tube 460.

In some embodiments, the pressure storage unit 450p includes intermediate liquid tank 430 at least partially filled with an auxiliary working liquid 430q, and an inverted cup structure (also referred to as pressure chamber) 420 situated therewithin at least partially filled with the auxiliary working liquid 430q.

As shown in Fig. 3A, the pressure chamber 420 is situated within the intermediate liquid tank 430 such that an opening 420n of pressure chamber 420 is suspended over a bottom surface 430b of the intermediate liquid tank 430 for allowing flow of the auxiliary working liquid 430q therebetween. The pressure chamber 420 is fluidly coupled to the external pressure source (not shown) via the input pipe / conduit 410, for receiving the gas-fluid (e.g., air) pressure, to thereby build-up temporal gasfluid pressure conditions thereinside. This way, temporal potential energy is stored in the pressure storage unit 450p, expressed by change / difference of the levels of the auxiliary working liquid 430q, inside the pressure chamber 420 and the intermediate liquid tank 430.

In some embodiments, the gas-fluid pressure inlet 410 is coupled, by one end thereof to a top portion of the pressure chamber 420, and may be connected by its other end to the pressure output (322 in Figs. 2B and 2D) of the thermo acoustic engine 110. The pressure storage unit 450p is fluidly coupled to the pumping unit 450 by a gasfluid pressure output pipe / conduit 440 that is connected to the top portion of the pressure chamber 420. In some cases, the gas-fluid pressure output pipe 440 can have a bigger diameter than the diameter of the gas-fluid pressure inlet pipe 410.

The pumping unit 450 includes a discharge tube (e.g., siphon) 460 extending upwardly from the (e.g., underground) liquid reservoir 500 a certain distance thereabove, and a gas-liquid vessel 470 fluidly coupled to the pressure storage unit 450p via the gas-fluid pressure output conduit 440 to receive the temporal gas-fluid pressure conditions evolving therein. As shown, a portion of the discharge tube 460 is accommodated within the gas-liquid vessel 470, such that a bottom opening 460i of the discharge tube 460 is suspended over a base surface 470b of the gas-liquid vessel 470. As seen, the gas-liquid vessel 470 and the discharge tube 460 can be configured to form an outer circumferential chamber SI therebetween for allowing the build-up of temporal gas-fluid pressure conditions thereinside. In some embodiments, the gas-liquid vessel 470 is configured to define an internal liquid passage/conduit 492 projecting from a liquid opening 470n formed in its base 470b a certain height into a bottom portion of the discharge tube 460, thereby forming an inner circumferential chamber S2 between the discharge tube 460and the internal liquid passage/conduit 492. The liquid internal passage/conduit 492 is configured to allow liquid to ingress and / or egress between the liquid reservoir 500 and the pumping unit 450.

In this non-limiting example, the gas-liquid vessel 470 and the discharge tube 460 coaxially mounted to form an annular bottom passage 450j therebetween, for passage of the gas-fluid pressure from the outer circumferential chamber SI to the inner circumferential chamber S2, so as to define a fluid flow path from the fluid-gas vessel 470 towards the liquid pushing member 490 disposed in some embodiments inside the discharge tube 460. In some embodiments, the discharge tube 460 may have a concentric configuration, as illustrated in Fig. 3A, or separated configuration as illustrated in Fig. 3B.

In its rest position, the liquid pushing member 490 is submerged in the liquid 500q of the liquid reservoir 500, some portion L of the liquid 500q is located above the liquid pushing member 490 in its rest (initial) position on an upper opening of the internal liquid passage/conduit 492. To this end, the liquid pushing member 490 can be made from a material (e.g. , metal or plastic) slightly denser than the density of the liquid 500q of the liquid reservoir 500. The liquid pushing member 490 is configured to enable passage of the liquid 500q thereabout between its external surface and inner surface of the discharge tube 460, such that the liquid 500q can freely flow between the pumping unit 450 and the liquid reservoir 500 via the internal liquid passage/conduit 492, when the liquid pushing member 490 is located over the upper opening of the liquid passage/conduit 492.

Thus, as the gas-fluid pressure conditions are evolving inside the gas-liquid vessel 470, portions of the liquid 500q are pushed downwardly from the outer circumferential chamber SI into the inner circumferential chamber S2, and via the internal liquid passage/conduit 492 into the liquid reservoir 500 e.g., when the liquid pushing member 490 rests over the upper opening of the internal liquid passage/conduit 492. The liquid pushing member 490 is configured for vertical movement (in an upward-downward direction) in response to the gas-fluid pressure received from the pressure storage unit 450p. The liquid pushing member 490 is configured to propel the liquid portion L covering it from above along the discharge tube 460 towards the outlet 460t of the discharge tube 460. In this non-limiting example, the liquid pushing member 490 is in the form of a solid ball, however, other possible shapes can be similarly contemplated.

The pumping unit 450 comprises in some embodiments a stopper element 494 projecting inwardly from a wall of the discharge tube 460. The stopper element 494 can be configured to stop further upward movement of the liquid pushing member 490 e.g., near the top-turn portion thereof when implemented with a siphon, while allowing liquid/water 500q to flow out of the pumping unit 450 via the liquid outlet 480t. When the liquid pushing member 490 arrives to the stopper element 494, its motion is stopped as a portion of the liquid thereby pushed is discharged via the liquid outlet 480t. The liquid pushing member 490 then falls downwardly towards the upper opening of the internal liquid passage/conduit 492, and sinks back in the liquid 500q as it returns to its initial position thereabove.

As shown in Fig. 3B, in possible embodiments the gas-liquid vessel (470 in Fig. 3A) can be implemented by a side tube 462 passing along a length of the liquid discharge tube 460, fluidly coupled by an upper portion thereof to the pressure storage unit 450p via the output pressure conduit 440 to receive the temporal gas-fluid pressure conditions therefrom. The side tube 462 can be configured with a J-shaped liquid passage extending into the discharge tube 460 at its J-shaped turn portion 462j. Accordingly, in this embodiment the liquid passage/conduit 492 is separated from the gas-liquid vessel (side tube) 462, and as seen, can be configured to extend alongside the upward turn of the J-shaped portion 462j inside the discharge tube 460.

Fig. 4 schematically illustrates embodiments of the pumping unit 450 shown in Figs. 3A and 3B, implemented without the liquid pushing member 490. In such embodiments the pumping units 450 are configured to propel quantities of the liquid 500q contained inside the discharge tube 460 upwardly along the discharge tube 460 towards and out of the liquid outlet 480t by the pressurized gas surges released thereinto. Accordingly, in the pumping units 450 shown in Fig. 4 discharge tube 460 is implemented without the stopper element 494.

Referring now to Figs. 5A to 5C, schematically illustrating operational principles of the pump system 400 according to some embodiments of the present disclosure utilizing the liquid pushing member 490. Fig. 5A shows an initial / rest state of the pump system 400, in which the auxiliary working liquid 430q levels in the pressure chamber 420 and in the intermediate liquid tank 430 are substantially the same. As shown, the pumping unit 450 is at least partially submerged in the liquid 500q of the liquid reservoir 500, while the liquid pushing member 490 is situated over the upper opening of the liquid passage/conduit 492.

In Fig. 5B, pressure is being supplied to pressure chamber 420 for the storage of the temporal pressure conditions (pressurized gas) evolving thereinside. This causes change in the levels of the auxiliary working liquid 430q in the pressure chamber 420 and in the intermediate liquid tank 430 z.e., the level of the auxiliary working liquid 430q in the pressure chamber 420 is reduced and elevated in the intermediate liquid tank 430.

As the pressurized gas from the pressure chamber 420 is being supplied to the gas-liquid vessel 470 of the pumping unit 450 through the pressure output pipe 440, the liquid level in the circumferential outer chamber SI of the gas-liquid vessel 470 is pushed down via the bottom passage 450j into the circumferential inner chamber S2, to conform to the pressure conditions inside the pressure chamber 420 z.e., the same temporal pressure conditions are built-up in the pressure chamber 420, output pressure pipe 440, and the circumferential outer chamber SI.

As the liquid 500q is passed into the circumferential inner chamber S2, it passes downwardly under the liquid pushing member 490, so as to allow liquid to flow from the pumping unit 450 to the liquid reservoir 500 through the internal liquid passage/conduit 492. In possible embodiments, the liquid pushing member 490 is also configured to permit passage of the liquid 500q upwardly inside the discharge tube z.e., the discharge tube 460 is not sealed for liquid passage by the liquid pushing member 490.

As demonstrated in Fig. 4C, when the pressurized gas received via the pressure output pipe / conduit 440 reaches the bottom passage 450j (connecting between the circumferential chambers SI and S2), a surge of pressurized gas is released through the circumferential outer chamber S2 into the discharge tube 460. This results in release of the pressure conditions (the stored potential energy) in the pressure chamber 420, thereby leveling the working auxiliary working liquid 430q levels in the pressure chamber 420 and in the intermediate liquid tank 430. The surge of pressurized gas introduced into the discharge tube 460 propels the liquid pushing member 490 upwardly, thereby pushing the portion L of the liquid 500q thereabove towards the liquid outlet 460t. With reference to Fig. 3A, the efficiency and optimal working point of the pump system 400 is determined in some embodiments by: a) the ratio of the work required to displace the liquid 430q in the intermediate water tank 430, and the work required to lift the liquid quantity A/i (representing the amount of liquid L above the liquid pushing member 490, as shown in Figs. 5A to 5C) along the AH column (representing the lifting height in the discharge tube towards its outlet 480t); and b) the volume of compressed gas/air required to lift the liquid/water quantity L. Therefore, for each case of well depth and supplied pressurized gas level, there will be an optimal geometrical configuration of the components of the pumping unit 450 for pumping desired liquid/water quantity L.

Referring now to Figs. 6A and 6B, graphically illustrating performance chart for specific pump configurations, where the efficiency is defined as the ratio of energy required to raise the column of water, to the energy supplied to the intermediate water tank. In particular, Fig. 6A shows a graph of efficiency [%] as function of pumping height above water [m] level for a configuration with a fixed submerged depth of 0.8m and a supply pressure of 8000 Pa. Fig. 6B shows a graph of efficiency [%] as function of submerged depth [m] for a configuration with a fixed pumping height of 12m.

As seen, when the submersion depth of the pump is fixed, maximal efficiency will be achieved when pumping to the maximal height allowed by the specific pump configuration. When the pumping height is fixed, changing the submerged depth of the pump (and consequently the supply pressure), as it happens when liquid/water level within the well changes, pumping efficiency will increase to a plateau.

It is to be noted that utilizing the presently disclosed configuration is by no means limiting and the teachings herein can be performed utilizing any other compressed air supply techniques, such as but not limited to, a manual air pump, an electrical air pump, a wind energy harvester, a steam generator, etc., mutatis mutandis.

It should be understood that throughout this disclosure, where a process or method is shown or described, the steps of the method may be performed in any order or simultaneously, unless it is clear from the context that one step depends on another being performed first. It is also noted that terms such as main, secondary first, second,... etc. may be used to refer to specific elements disclosed herein without limiting, but rather to distinguish between the disclosed elements. Relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "up," "down," "top" and "bottom", as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.), and similar adjectives in relation to orientation of the described elements/components refer to the manner in which the illustrations are positioned on the paper, not as any limitation to the orientations in which these elements/components can be used in actual applications.

It is to be understood that the presently disclosed subject matter is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The presently disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present presently disclosed subject matter.