Portable mute invisible power generation device
By combining a diesel combustion unit, a ring rotor power generation unit, and a condensation latent heat recovery unit, the problems of traditional power generation equipment being heavy, noisy, and flammable and explosive are solved, achieving efficient and silent power generation and simulated infrared targets, thus improving the stability and concealment of individual soldier power supply.
Patent Information
- Application Number
- CN202510964759.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-10-28
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing diesel generators are heavy, noisy, difficult to miniaturize, and unsafe. Gasoline generators are flammable and explosive, making them unsuitable for individual soldiers to carry. Traditional power generation equipment is difficult to provide stable power support on the battlefield.
The system employs a diesel combustion unit, a ring rotor power generation unit, and a condensation latent heat recovery unit, combined with simulation components, to achieve silent power generation through high-pressure steam generation and condensed water vapor. The simulation components are used to simulate infrared false targets, and non-electronic components are designed to control the arm's movement.
It achieves efficient and silent power generation, high thermal energy utilization, high power generation efficiency, good equipment concealment, and can work reliably in harsh environments, providing stable power support.
Smart Images

Figure CN120845145A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power generation equipment, specifically a portable, silent, and stealthy power generation device. Background Technology
[0002] In informationized and networked warfare, support from data links, communication links, command links, and intelligence links is crucial. Combat units or individual soldiers need to carry a large amount of informationized equipment for reconnaissance, communication, command, positioning, and data processing during missions, consuming significant amounts of electrical energy. Continuously charging these electronic devices in field environments presents a challenge. According to US military data, special operations units require each soldier to carry nearly 50 lithium batteries, with the batteries alone weighing over 10 kilograms. Therefore, developing efficient and lightweight mobile power sources or generators to provide sufficient power for combat units or individual soldiers will significantly improve troop mobility and combat capabilities. Traditional fuel-powered generators, fueled by diesel, gasoline, or kerosene, are currently the main power generation equipment for militaries worldwide. They typically use a four-stroke fuel engine to drive an electric rotor to generate electricity. Diesel generators are the most common, offering advantages such as high power output, readily available fuel, and high safety, but also significant disadvantages. Diesel generators have complex internal mechanical structures, are prone to failure, and are difficult to miniaturize. Currently, the smallest diesel generator has an electrical power of 3 kilowatts and weighs over 50 kilograms, which is completely unsuitable for the needs of squads or individual soldiers. In addition, diesel generators vibrate strongly and are noisy, which is very detrimental to battlefield concealment. Gasoline generators can be miniaturized, reducing the weight to less than 10 kilograms, but gasoline is flammable and explosive, not a safe fuel, and the exhaust gas temperature of gasoline generators can reach 300°C, making them easy targets for enemy infrared-guided weapons, which does not meet the needs of battlefield operations.
[0003] Therefore, we need to develop a portable, silent, and stealthy power generation device. Summary of the Invention
[0004] The purpose of this invention is to provide a portable, silent, and stealthy power generation device to solve the problems mentioned in the background art.
[0005] Portable, silent, stealthy power generation device, including power generation components and simulation components; The power generation components include: The diesel combustion unit atomizes large diesel droplets into small diesel gas clouds, which are then fully mixed with combustion air to improve combustion efficiency. The high-pressure steam generation unit utilizes self-circulating steam generation technology to form a water-steam circulation system that requires no power unit. The annular rotor power generation unit generates electricity by expanding high-pressure steam. The latent heat recovery unit for condensation produces drinking water and links to infrared simulation components by condensing water vapor. A simulation component, wherein high-temperature distilled water is injected into the simulation component to simulate an infrared false target.
[0006] Furthermore: the output end of the fuel supply unit is connected to the input end of the diesel combustion unit, a high-pressure steam generating unit is provided outside the diesel combustion space of the diesel combustion unit, the input end of the high-pressure steam generating unit is connected to a water bottle, and the output end is connected to a ring rotor power generation unit, a condensation latent heat recovery unit is provided above the diesel combustion unit, a combustion-supporting fan is provided above the condensation latent heat recovery unit, and the power supply unit of the combustion-supporting fan includes a battery pack.
[0007] Furthermore: the oil supply unit includes an oil tank and an oil pump, with the input end of the oil pump connected to the oil tank. The diesel combustion unit includes an igniter and an atomizing nozzle. The output end of the oil pump is connected to the input end of the atomizing nozzle. The atomized oil droplets output from the output end of the atomizing nozzle come into contact with the igniter. The atomized oil droplets burn in the combustion chamber after being ignited by the igniter. The high-pressure steam generating unit includes a metal tube spirally surrounding the outside of the combustion chamber; the input end of the metal tube is connected to the output end of the water pump in the water bottle, and the input end of the metal tube is connected to the water bottle and the annular rotor power generation unit respectively through a multi-port pipe; the annular track is slidably connected to the magnetic rotor by ball bearings. The annular rotor power generation unit includes a self-excited coil, which is wrapped around the outside of the annular track, and a magnetic rotor is arranged on the inside of the annular track; the metal tube input end is connected to the annular rotor power generation unit by connecting to the inside of the annular track. The latent heat recovery unit is arranged in a coil spring shape between the combustion fan and the air inlet of the diesel combustion unit.
[0008] Furthermore: the simulation component includes a dummy body, with water inlets and outlets respectively provided on the two simulated legs of the dummy body; an automatic water stop valve is provided on the inner side of the connection between the dummy body and the movable arm; one end of the automatic water stop valve is connected to a lead wire; the movable arm is L-shaped in its normal state, and a power compartment is provided on the outer side of the movable arm. Furthermore, the interior of the power chamber is a vacuum and is filled with a liquid that will vaporize at temperatures above 45°C.
[0009] Furthermore: the vaporized liquid is diethyl ether.
[0010] Furthermore: the automatic water stop valve includes a lower chamber, a movable plate is slidably connected inside the lower chamber, an upper chamber can be fitted and inserted into the upper end of the movable plate, a lead wire is connected to one end of the movable plate, waterproof gaskets are connected to the outer walls on both sides of the lower chamber and the upper chamber, and a water outlet is opened on the inner side of the upper chamber.
[0011] Furthermore: the water bottle includes a storage chamber located on the outside of the water bottle, the upper end of the storage chamber is provided with a movable door that is easy to open and close, a connector is provided on one side of the storage chamber where it communicates with the water bottle, a hollow first water guide tube is slidably connected to the inner side of the connector, one end of the first water guide tube is connected to a funnel-shaped liquid-receiving funnel, the upper end of the liquid-receiving funnel is connected to a water-collecting net for collecting water, and an anti-detachment component is fixedly connected to the outer wall of the other end of the first water guide tube.
[0012] Furthermore: the water collection network includes a mesh condensate net, and multiple sets of the condensate nets are connected by filter suction pipes. The upper end of the filter suction pipe is connected to a second water guide pipe, and one end of the second water guide pipe is connected to a drain interface. The rectangular ends of the water collection network that are not connected to the liquid receiving funnel are all provided with thin ropes.
[0013] Furthermore: the filter water suction pipe includes a mesh fabric arranged in the innermost and outermost layers, with a filter membrane disposed between the two layers of mesh fabric.
[0014] Compared with the prior art, the beneficial effects of the present invention are: Firstly, the special combustion chamber structure ensures complete combustion of diesel fuel, achieving a diesel thermal energy utilization rate of over 99%. Secondly, the coaxial diffraction heat exchange structure can convert the thermal energy of diesel combustion into the kinetic energy of water vapor as much as possible, with a thermal conversion efficiency of over 96% and an exhaust gas temperature of less than 60°C. Thirdly, there is a permeable steam generator, where the heat energy generated by diesel combustion is used to evaporate and heat the water in the spiral pipe, producing high-temperature and high-pressure steam at 250°C, which drives the annular expander to do work. Fourth is the annular expander, which uses steam kinetic energy to drive the rotor in the annular track. It has low energy loss and a working efficiency of up to 90%, far exceeding that of traditional 4-stroke engines. Fifth, carbon fiber self-excited coils. Special carbon fiber coils have an excitation effect and can generate a magnetic-like relationship with the rotor of hot graphite material, thereby generating a power generation effect by the coil cutting the magnetic field. Sixth, simulation components can control the movements of the simulated human hand without relying on electronic components, which can increase the attraction to the environment. At the same time, the non-electronic components can improve the reliability of the equipment in harsh environments. Seventh, the water bottle is designed to collect water in extreme environments using simple tools, including collecting water from the air and from conditions such as mud and puddles, to make it drinkable or near-drinkable. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 Two schematic diagrams illustrating the structure of this invention; Figure 3 This is a schematic diagram illustrating the principle of the present invention; Figure 4 This is a schematic diagram of the simulated component structure of the present invention; Figure 5 This is a schematic diagram of the simulated component of the present invention when its arm is extended; Figure 6 It is a schematic diagram of the structure of the present invention; Figure 7 This is a two-dimensional structural schematic diagram of the present invention; Figure 8 This is a schematic diagram of the water bottle's water-collecting function structure according to the present invention; Figure 9 for Figure 8 A schematic diagram of the structure of region A; Figure 10 This is a schematic diagram of the cross-sectional structure of the filter water suction pipe of the present invention; Figure 11 This is a cross-sectional view of the rotor power generation structure of the present invention; Figure 12 For the present invention Figure 11 A schematic diagram of the structure of region B.
[0016] In the picture: 1. Fuel supply unit; 2. Simulation component; 3. Water bottle; 4. Diesel combustion unit; 5. High-pressure steam generation unit; 6. Ring rotor power generation unit; 7. Battery pack; 8. Combustion fan; 9. Condensation latent heat recovery unit; 201. Dummy body; 202. Water inlet; 203. Drain outlet; 204. Movable arm; 205. Automatic water stop valve; 206. Lead wire; 207. Power compartment; 2051. Lower compartment; 2052. Movable plate; 2053. Upper compartment; 2054. Waterproof pad; 2055. Water outlet; 301. Storage chamber; 302. Connector; 303. First water guide pipe; 304. Anti-detachment component; 305. Liquid receiving funnel; 306. Water collection net; 3061, Condensation mesh; 3062, Filter suction pipe; 3063, Second water guide pipe; 3064, Drainage interface; 3065, Fine rope; 30621, Woven net; 30622, Filter membrane; 61, Magnetic rotor; 62, Circular track; 63, Ball bearing. Detailed Implementation
[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example
[0018] like Figure 1-3 As shown, a portable, silent, stealthy power generation device includes a power generation component and a simulation component; The power generation components include: The diesel combustion unit 4 atomizes large diesel droplets into small diesel gas clouds, which are then fully mixed with combustion air to improve combustion efficiency. High-pressure steam generation unit 5 utilizes self-circulating steam generation technology to form a water-steam circulation system that requires no power unit; The annular rotor power generation unit 6 generates electricity by expanding high-pressure steam. The condensation latent heat recovery unit 9 prepares drinking water and links infrared simulation components by condensing water vapor; Simulation component 2, wherein high-temperature distilled water is injected into the simulation component to simulate an infrared false target.
[0019] Furthermore: the output end of the fuel supply unit 1 is connected to the input end of the diesel combustion unit 4, a high-pressure steam generating unit 5 is provided outside the diesel combustion space of the diesel combustion unit 4, the input end of the high-pressure steam generating unit 5 is connected to a water bottle 3, and the output end is connected to a ring rotor power generation unit 6, a condensation latent heat recovery unit 9 is provided above the diesel combustion unit 5, a combustion-supporting fan 8 is provided above the condensation latent heat recovery unit 9, and the power supply unit of the combustion-supporting fan 8 includes a battery pack.
[0020] Furthermore: the oil supply unit 1 includes an oil tank and an oil pump, and the input end of the oil pump is connected to the oil tank. The diesel combustion unit 4 includes an igniter and an atomizing nozzle. The output end of the oil pump is connected to the input end of the atomizing nozzle. The atomized oil droplets output from the output end of the atomizing nozzle come into contact with the igniter. The atomized oil droplets burn in the combustion chamber after being ignited by the igniter. The high-pressure steam generating unit 5 includes a metal pipe spirally surrounding the outside of the combustion chamber; the input end of the metal pipe is connected to the output end of the water pump in the water bottle, and the input end of the metal pipe is connected to the water bottle 3 and the annular rotor power generation unit 6 respectively through a multi-port pipe. The annular rotor power generation unit 6 includes a self-excited coil, which is wrapped around the outside of the annular track, and a magnetic rotor is arranged on the inside of the annular track; the metal tube input end is connected to the annular rotor power generation unit by connecting to the inside of the annular track; the annular track 62 is slidably connected to the magnetic rotor 61 by ball bearings 63. The latent heat recovery unit 9 is arranged in a coil spring shape between the combustion fan 8 and the air inlet of the diesel combustion unit 4.
[0021] Through the connection method of the above structure, we can see that the diesel combustion unit 4 expels the oil into a mist through the atomizing nozzle. The air blown in by the combustion fan 8 makes the oil and air come into full contact, resulting in more complete combustion. The heat released by the combustion turns the liquid flowing in the metal tube of the high-pressure steam unit 5 into steam. The steam then enters the annular guide rail of the annular rotor discharge unit 6, driving the rotor to rotate and cut the magnetic field lines, thereby generating an electric current. The actual measured temperature of the high-pressure steam is about 250°C, while the rotor speed can reach 5000 rpm.
[0022] Meanwhile, the 250°C high-pressure water vapor expands and does work, becoming 100°C low-pressure water vapor, which enters the annular latent heat regenerator. The combustion air in the combustion unit cools it down, which not only increases the temperature of the combustion air and the diesel combustion efficiency, but also reduces the 100°C low-pressure water vapor to 60°C distilled water, which can be used for drinking or making infrared decoys. Example
[0023] Building upon the above, the designers went a step further: As described above, we connect the condensate outlet of the power generation equipment through a hose, and then connect distilled water at around 60°C to the simulation component through the hose. The purpose is to induce enemy infrared detection by using the infrared signal emitted by the warm water inside the dummy. However, we considered that if the dummy remains motionless, the enemy might be able to see through the disguise. In reality, combat environments are harsh and complex. Therefore, we hope to design a system that can achieve human-like movement of the dummy after it is injected with warm water, relying solely on a simple structure and without electronic components.
[0024] like Figure 4-7As shown: The simulation component includes a dummy body 201, two simulated legs of the dummy body 201 respectively equipped with water inlets 202 and drain outlets 203, an automatic water stop valve 205 is provided on the inner side of the connection between the dummy body 201 and the movable arm 204, one end of the automatic water stop valve 205 is connected to a lead wire 206, the movable arm 204 is normally L-shaped, and a power chamber 207 is provided on the outer side of the movable arm 204. The interior of the power chamber 207 is in a vacuum state and filled with a temperature above 45°. The liquid that will vaporize at a certain temperature can be selected, including easily vaporized liquids such as ether. The automatic stop valve 205 includes a lower chamber 2051, a movable plate 2052 that is slidably connected inside the lower chamber 2051, an upper chamber 2053 that can be fitted into the upper end of the movable plate 2052, a lead wire 206 connected to one end of the movable plate 2052, waterproof gaskets 2054 connected to the outer walls on both sides of the lower chamber 2051 and the upper chamber 2053, and a water outlet 2055 opened on the inner side of the upper chamber 2053.
[0025] The working principle and effects of the above structure are explained in detail as follows: First, the power chamber 207 must be a vacuum and filled with a vaporizable liquid. As warm water is introduced, the liquid temperature rises and it continuously vaporizes, filling the power chamber 207 and pushing the movable arm 204 to extend. Similarly, as the temperature decreases, the movable arm 204 will continuously contract. When the power chamber 207 is fully extended, it will also drive the lead wire 206 to pull the movable plate 2052 to close, thereby preventing the heat from the dummy body 201 from supplementing the movable arm 204. When the temperature inside the movable arm 204 drops to a certain level, the movable arm 204 contracts and at the same time opens the automatic water stop valve 205, thus achieving temperature interaction. Subsequently, the temperature inside the movable arm 204 rises again and repeats the above phenomenon, so that the movable arm 204 can achieve simulated movement for a certain period of time, thus making it more deceptive. Example
[0026] Because this design was developed for wartime use, it has higher requirements for its use in various extreme environments. Therefore, the designers proposed a solution for quickly replenishing the water needed for power generation or drinking after water resources are scarce and the water in the bottle is depleted. This led to the design of the following structure: like Figure 8-10The automatic water stop valve 205 includes a lower chamber 2051, a movable plate 2052 slidably connected inside the lower chamber 2051, an upper chamber 2053 that can be fitted into the upper end of the movable plate 2052, a lead wire 206 connected to one end of the movable plate 2052, waterproof gaskets 2054 connected to the outer walls on both sides of the lower chamber 2051 and the upper chamber 2053, and a water outlet 2055 opened on the inner side of the upper chamber 2053.
[0027] The water bottle includes a storage chamber 301 located on the outside of the water bottle. The upper end of the storage chamber 301 has a movable door for easy opening and closing. A connector 302 is located on one side of the storage chamber 301 where it communicates with the water bottle 3. A hollow first water guide tube 303 is slidably connected to the inner side of the connector 302. One end of the first water guide tube 303 is connected to a funnel-shaped liquid-receiving funnel 305. The upper end of the liquid-receiving funnel 305 is connected to a water-collecting net 306, which includes a mesh condensate net 30. 61. Multiple sets of condensate nets 3061 are connected by filter suction pipes 3062. The upper end of the filter suction pipe 3062 is connected to a second water guide pipe 3063. One end of the second water guide pipe 3063 is connected to a drain interface 3064. The rectangular ends of the water collection net 306 that are not connected to the liquid receiving funnel 305 are all provided with thin ropes 3065. The filter suction pipe 3062 includes a woven net 30621 set in the innermost and outermost layers. A filter membrane 30622 is set between the two layers of woven net 30621.
[0028] Under normal conditions, the water collection net 306 is placed in the storage chamber 301. When the water bottle is empty, it provides replenishment for both non-drinking water and equipment water. The use of the water collection net 306 can be selected based on the site environment. One method of using the water collection net 306 involves removing it from the storage chamber 301, unfolding it, and tying it to a tree branch at a suitable distance using a thin rope 3065, thus suspending it in the air. Especially at night and in the morning when fog is heavy, the condensate net 3061 can intercept the fog, causing it to adhere to the net and, under gravity, enter the liquid-receiving funnel 305. 05 Entering step 3, the water collection net 3061 is made of nylon. If the air is dry, some undrinkable water may be found. The water collection net 306 can be completely immersed in dirty water. The dirty water will gradually seep into the interior of the filter suction pipe 3062 and accumulate. Then, simply remove the water collection net 306, invert it, and let the water flow through the internal pipe of the filter suction pipe 3062 and through the second water guide pipe 3063. After the valve of the drain interface 3064 is opened, clean water can be discharged. The other end of the first water guide pipe 303 is fixedly connected to the outer wall with an anti-detachment component 304.
[0029] It should be noted that the material of the mesh 30621 is nylon and other polymer materials, while the filter membrane 30622 can be a microporous filter element. This filtration method is a wartime emergency method. The water collection mesh 306 needs to be replaced and cleaned frequently. The filtered water quality may not meet the standards for drinking water to a certain extent, but it can fully meet wartime needs.
[0030] It should be noted that, from the appendix Figure 1-2 As shown, the upper part of the generator housing is located above the diesel combustion unit, and a ventilation grid is also located above the combustion fan.
[0031] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection defined by the claims submitted herein.
Claims
1. A portable, silent, and stealthy power generation device, characterized in that: Includes power generation components and simulation components; The power generation components include: The diesel combustion unit atomizes large diesel droplets into small diesel gas clouds, which are then fully mixed with combustion air to improve combustion efficiency. The high-pressure steam generation unit utilizes self-circulating steam generation technology to form a water-steam circulation system that requires no power unit. The annular rotor power generation unit generates electricity by expanding high-pressure steam. The latent heat recovery unit for condensation produces drinking water and links to infrared simulation components by condensing water vapor. A simulation component, wherein high-temperature distilled water is injected into the simulation component to simulate an infrared false target.
2. The portable, silent, and stealthy power generation device according to claim 1, characterized in that: It also includes an oil supply unit, the output of which is connected to the input of a diesel combustion unit. A high-pressure steam generating unit is located outside the diesel combustion space of the diesel combustion unit. The input of the high-pressure steam generating unit is connected to a water bottle, and its output is connected to a ring rotor generator unit. A latent heat recovery unit is located above the diesel combustion unit, and a combustion-supporting fan is located above the combustion-supporting fan. The power supply unit for the combustion-supporting fan includes a battery pack.
3. The portable, silent, stealthy power generation device according to claim 2, characterized in that: The oil supply unit includes an oil tank and an oil pump, with the input end of the oil pump connected to the oil tank. The diesel combustion unit includes an igniter and an atomizing nozzle. The output end of the oil pump is connected to the input end of the atomizing nozzle. The atomized oil droplets output from the output end of the atomizing nozzle come into contact with the igniter. The atomized oil droplets burn in the combustion chamber after being ignited by the igniter. The high-pressure steam generating unit includes a metal tube spirally surrounding the outside of the combustion chamber; the input end of the metal tube is connected to the output end of the water pump in the water bottle, and the input end of the metal tube is connected to the water bottle and the annular rotor power generation unit respectively through a multi-port pipe. The annular rotor power generation unit includes a self-excited coil, which is wrapped around the outside of an annular track, and a magnetic rotor is arranged on the inside of the annular track; the metal tube input end is connected to the annular rotor power generation unit by connecting to the inside of the annular track; the annular track is slidably connected to the magnetic rotor by ball bearings. The latent heat recovery unit is arranged in a coil spring shape between the combustion fan and the air inlet of the diesel combustion unit.
4. The portable, silent, stealthy power generation device according to claim 3, characterized in that: The simulation component includes a dummy body, two simulated legs of the dummy body respectively provided with water inlets and drain outlets, an automatic water stop valve provided on the inner side of the connection between the dummy body and the movable arm, one end of the automatic water stop valve is connected to a lead wire, the movable arm is L-shaped in normal state, and a power compartment is provided on the outer side of the movable arm.
5. The portable, silent, stealthy power generation device according to claim 4, characterized in that: The interior of the power compartment is a vacuum and is filled with a liquid that will vaporize at temperatures above 45°C.
6. The portable, silent, stealthy power generation device according to claim 5, characterized in that: The vaporized liquid is diethyl ether.
7. The portable, silent, stealthy power generation device according to claim 6, characterized in that: The automatic water stop valve includes a lower chamber, a movable plate that is slidably connected inside the lower chamber, an upper chamber that can be fitted and inserted into the upper end of the movable plate, a lead wire connected to one end of the movable plate, waterproof gaskets connected to the outer walls on both sides of the lower and upper chambers, and a water outlet opened on the inner side of the upper chamber.
8. The portable, silent, stealthy power generation device according to claim 2, characterized in that: The water bottle includes a storage chamber located on the outside of the water bottle. The upper end of the storage chamber is provided with a movable door that is easy to open and close. A connector is provided on one side of the storage chamber where it communicates with the water bottle. A hollow first water guide tube is slidably connected to the inner side of the connector. One end of the first water guide tube is connected to a funnel-shaped liquid-receiving funnel. The upper end of the liquid-receiving funnel is connected to a water-collecting net for collecting water. An anti-detachment component is fixedly connected to the outer wall of the other end of the first water guide tube.
9. The portable, silent, stealthy power generation device according to claim 8, characterized in that: The water collection network includes a mesh condensate net, and multiple sets of the condensate nets are connected by filter suction pipes. The upper end of the filter suction pipe is connected to a second water guide pipe, and one end of the second water guide pipe is connected to a drain interface. The rectangular ends of the water collection network that are not connected to the liquid receiving funnel are all provided with thin ropes.
10. The portable, silent, stealthy power generation device according to claim 9, characterized in that: The filter water suction pipe includes a mesh fabric arranged in the innermost and outermost layers, with a filter membrane disposed between the two layers of mesh fabric.