WO2022079522A1

WO2022079522A1 - Flow generator and method for gas sampling in quiescent volumes

Info

Publication number: WO2022079522A1
Application number: PCT/IB2021/058592
Authority: WO
Inventors: Deanna A. LACOSTE; William L. Roberts
Original assignee: King Abdullah University Of Science And Technology
Priority date: 2020-10-14
Filing date: 2021-09-21
Publication date: 2022-04-21

Abstract

A gas flow generator (200, 500) for generating a gas flow in a quiescent volume includes an inlet module (202) configured to receive a gas (216); a measuring module (204) configured to measure a parameter associated with the gas (216); a heating module (204) configured to heat the gas (216); an outlet module (208) configured to discharge the gas (216) outside the gas flow generator (200, 500); and an orientation control module (210) configured to attach the outlet module (208) to a tank that holds the gas (216). The orientation control module (210) is further configured to maintain the inlet module (202) below the outlet module (208) relative to a gravity direction G.

Description

FLOW GENERATOR AND METHOD FOR GAS SAMPLING IN QUIESCENT VOLUMES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/091 ,485, filed on October 14, 2020, entitled “FLOW GENERATOR FOR GAS

SAMPLING IN QUIESCENT VOLUMES,” and U.S. Provisional Patent Application No. 63/115,324, filed on November 18, 2020, entitled “FLOW GENERATOR AND METHOD FOR GAS SAMPLING IN QUIESCENT VOLUMES,” the disclosures of which are incorporated herein by reference in their entirety.

BACKGROUND

TECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to a system and method for generating a gas flow in a given enclosure, and more particularly, to a gas flow generator to be used in an enclosed motionless gas for promoting accurate gas sampling within a static/quiescent volume.

DISCUSSION OF THE BACKGROUND

[0003] In a large variety of industrial systems, it is common to have quiescent volumes (in the range of a liter to several cubic meters) filled or partially filled, with gases. For example, such quiescent volumes can be found in various tanks associated with vehicles, such as planes, boats, helicopters, cars, trucks, or trains. Also, these volumes can be found in the petrochemical, pharmaceutical, or chemical plants. Partially filled tanks, acoustic dampers, relaxation cells, cooling, drying and warming chambers are typical examples used by these industries that inherently have one or more quiescent volumes.

[0004] In some of these enclosures, the local gas composition or other properties of the gas may evolve in time. For example, as shown in Figure 1 , a fluid tank 100 may have a housing 102 configured to store a mixture 104, which contains a liquid 106 and solid components 108. The mixture 104 may be supplied to the housing through an inlet 110. After some time, the solid components 108 sediment to the bottom of the tank, while the liquid 106 is positioned mainly above the solid components. A liquid outlet 112 is used to collect the separated liquid 106 from the tank. This separation process is encountered in many industrial settings. A bottom outlet 114 may be used to evacuate the solid components 108 when the tank needs to be cleaned out.

[0005] However, during the separation process, it is possible that one or more gases 120 are formed within the tank and these gases accumulate at the upper part of the tank. In one embodiment, the one or more gases may be undesired or dangerous, and for this reason, their presence and/or concentrations need to be monitored. This is traditionally achieved with a sensor 130 placed at the top of the tank. However, because during the separation process there is a reduced movement of the gas 120 or the mixture 104, the readings of the sensor 130 may be inaccurate as the gas 120 can be stratified based on one or more of its characteristics (for example, its temperature) due to the lack of movement.

[0006] In another embodiment, if any gas property of the entire volume of gas in the tank has to be measured by the local probe or sensor 130 at a faster rate than the diffusion or natural convection time scale of the gas, the measurement system needs to be coupled to a flow generator to achieve the desired movement of the gas. Indeed, as the gas 120 is at rest in the housing 102, a flow generator is necessary to displace the gas to insure a correct sampling, at the sensor, of the gas to be analyzed. In addition, for quiescent enclosures, disruptive measurement techniques such as those modifying the gas composition, must also rely on the presence of the flow generators.

[0007] There are several methods to generate a gas flow within a closed enclosure. Typical examples are those involving mechanical devices such as fans or pumps. Other devices use a high voltage that is applied between specifically designed electrodes to generate an ionic wind. However, for the cases where the weight of the measuring system is sensitive for the entire systems, or when mechanical noise, moving parts, or high voltages are not acceptable, the existing solutions may not work.

[0008] Thus, there is a need for an alternative flow generator, that has nomoving part, produces a low noise, has a low weight, and is inexpensive. In addition, such a new flow generator is desired to be compatible with transportation systems that experience frequent changes in orientation with respect to gravity, such as planes, helicopters, boats, cars, trucks, etc. BRIEF SUMMARY OF THE INVENTION

[0009] According to an embodiment, there is a gas flow generator for generating a gas flow in a quiescent volume. The gas flow generator includes an inlet module configured to receive a gas, a measuring module configured to measure a parameter associated with the gas, a heating module configured to heat the gas, an outlet module configured to discharge the gas outside the gas flow generator, and an orientation control module configured to attach the outlet module to a tank that holds the gas. The orientation control module is further configured to maintain the inlet module below the outlet module relative to a gravity direction G.

[0010] According to another embodiment, there is a gas flow generator system for generating a gas flow. The gas flow generator system includes a tank having a housing configured to hold a gas, a gas flow generator located inside the housing and configured to generate the gas flow and measure a parameter associated with the gas, and an orientation control module configured to attach the gas flow generator to the housing. The orientation control module is configured to hold the gas flow generator in a same orientation relative to a gravity direction G when the tank changes an orientation relative to the gravity direction G.

[0011 ] According to yet another embodiment, there is a method for generating a gas flow with a gas flow generator, and the method includes attaching the gas flow generator to an interior wall of a tank, wherein the tank holds a static gas, turning on the gas flow generator by generating heat inside the gas flow generator, generating a steady-state gas flow through the gas flow generator, adjusting a speed of the gas flow, measuring a parameter of the gas that flows through the gas flow generator, and turning off the heat generated inside the gas flow generator to stop the flow of the gas.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a schematic diagram of a tank that separates solid components from a liquid, which also generates a gas;

[0014] Figures 2A to 2C show various implementations of a novel gas flow generator that has no moving parts;

[0015] Figure 3 shows an orientation control device that ensures that the gas flow generator maintains a same alignment with the gravity;

[0016] Figure 4 illustrates the distribution of the center of mass for various modules of the gas flow generator;

[0017] Figure 5 shows another implementation of a novel gas flow generator without moving parts; and

[0018] Figure 6 is a flow chart of a method for using a gas flow generator in a tank having a quiescent volume.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a flow generator that has five functional regions. However, the embodiments to be discussed next are not limited to a flow generator having five functional regions, but may be applied to flow actuators that have more or less regions.

[0020] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0021] According to an embodiment, a novel flow generator for gas sampling has no moving parts. The flow generator has an inlet module, a measuring module, a heating module, an exhaust module, and an orientation (e.g., tilt) control module. Although the modules are described next in this order, one skilled in the art would understand that the order of some of the modules may be reversed or modified and/or some of the modules may be omitted. Figure 2A shows a flow generator 200 that includes the inlet module 202, the measuring module 204, the heating module 206, the exhaust module 208, and the orientation control module 210. The orientation control module 210 is shown in this figure being directly attached to a wall 212 of an enclosure 214, which holds a gas 216. The enclosure 214 may be the tank of a vehicle or of a plant.

[0022] The inlet module 202 of the flow generator can be implemented as a tube or a nozzle. In one application, it is possible to add a fluidic diode valve (e.g., a Tesla valve) 202-1 , for promoting the gas flow in the downstream direction D only. This is preferred because all the gas 216 that enters the inlet module 202 should move along the downstream direction D so that the measuring module can measure its parameter(s). Depending on the application, additional parts can be added to the inlet module. For example, in the case of flammability tests in the flow generator, a flame arrester 202-2 could be used in addition to the fluidic diode valve 202-1 . Note that these additional elements are only schematically illustrated in Figure 2A. A more practical implementation of these additional elements is illustrated in later figures. Another possible additional element to be added for dusty or multi-phase environments is one or more filters 202-3, to ensure that the dust is not entering the measuring module.

[0023] The measuring module 204 is shown in Figure 2A being located downstream and adjacent to the inlet module 202. However, the measuring module 204 may be placed after the heating module 206, or may be even combined with the exhaust module 208 or the inlet module 202. The measuring module 204 defines a volume in the flow generator 200, which is set aside for the installation of one or more measurement elements, e.g., sensors or probes 205, depending on the application. The flow of gases 216 is forced to pass through this volume and thus, the one or more measurement elements 205 samples the gas. The measuring module may be shaped as a tube, a truncated cone, or a part of a sphere, and the sensor or sensors are placed within a bore or channel of the measuring module for being able to directly contact the gas flow.

[0024] The heating module 206 may include any means for heating an interior chamber of the module. A heating system such as an electric heater (ohmic heating) 207 may be used to increase the temperature of the gas in the range between 10 and 300 °C. In this module, the gas 216 expands and the local density decreases. It is noted that the density of the gas is inverse proportional with the temperature of the gas. Due to the buoyancy effect, the pocket of light gas that is inside the heating module 206 is convected downstream along direction D, in opposite direction to the gravity vector G. This convection process, which is originated due to the heating of the gas in the heating module, is responsible for the generation of a gas flow in the flow generator 200, irrespective of the status of the gas outside the flow generator. [0025] In other words, even if the gas 216 outside the flow generator 200 is static, i.e. , not moving at all as there is no internal source inside the tank 214 that makes the gas to move, the flow generator 200 forces a movement of the gas inside it by heating the gas in the heating module. One skilled in the art would understand that this “engine” for the gas flow can be placed anywhere along the flow generator. To obtain a gas flow that advances along the downstream direction D and not along the gravity G, it is necessary to keep a correct orientation of the entire flow generator 200 relative to the gravity, no matter how the tank 214 moves. This means that a longitudinal axis X of the flow generator, that is directed from the input to the output modules, needs to be aligned opposite to the gravity G at all times, even when the tank 214 in which the flow generator is placed is changing its orientation to the gravity. For this reason, the orientation control module 210 is added to the system to ensure the correct opposite alignment of the longitudinal axis X or downstream flow D relative to the gravity G.

[0026] The heat addition to the gas 216 is responsible for the flow generation and it is adjustable depending on the gas conditions and sampling requirements, e.g., to generate a faster flow, a larger density difference is required meaning a larger increase in temperature change is required. The change in the amount of heat that is supplied to the gas may be controlled with a controller 230, which may be a processor, mobile device, computer, i.e., any device having computing power. The controller 230 may be part of the flow generator 200. For example, in a case of air transportation for which the ground and cruise conditions are very different in terms of pressure and temperature, for keeping a constant flow in the probing area, the gas heating must be adjusted.

[0027] The controller 230 may be configured with software instructions to calculate the amount of heat necessary to obtain a certain speed for the gas flow. This calculation relies on the type of gas, the pressure in the tank, the temperature and/or pressure in the flow generator, the resistance of the heater, etc. Thus, in one embodiment, the controller 230 may be connected to additional sensors 232, located either in the heating module 206, and/or in other modules, for determining the temperature and/or pressure of the passing gas. Based on these software instructions and the collected readings, the controller 230 is then able to adjust the power supplied by a power source 234 to the heating element 207 of the heating module 206. The power supply 234 may be either part of the flow generator 200, or part of the tank 214. If the power supply 234 is part of the flow generator 200, the power supply may include a battery, a fuel cell, a solar cell, etc. If the power supply is part of the tank 214, it may be any kind of power supply.

[0028] After the gas 216 has expanded through the heating module 206, the gas exits the flow generator 200 through the exhaust module 208. In one embodiment, the exhaust module 208 can be implemented as a straight tube. Alternatively, the exhaust module 208 can have a specific shape to accelerate the gas flow. Depending on the application, the exhaust module 208 can also be equipped with a flame arrester 208-1 and/or filters 208-2. In any case, the pressure drop along the exhaust module 208 should always be smaller than the pressure drop along the inlet module 202. This condition is necessary to avoid a backward movement of the gas flow, i.e., along the gravity G instead of the downstream direction D. A pressure drop is defined in this application as being a pressure difference between the output and input of a given module, where the gas enters at the input and leaves at the output. A desired pressure drop is achieved by choosing the inner sizes of the flow generator.

[0029] While Figure 2A shows the inlet module 202, the measuring module

204, the heating module 206, and the outlet module 208 distributed in this order, Figure 2B shows the heating module 206 being placed adjacent to the inlet module 202 and the measuring module 204 being sandwiched between the heating module 206 and the outlet module 208. In another embodiment as illustrated in Figure 2C, the inlet module, the outlet module or both are formed as part of the heating module and the measuring module.

[0030] The orientation control module 210, as previously discussed, is added to the flow generator 200 to ensure that the downstream direction D and the longitudinal axis X are oriented opposite to the gravity G, even if the tank/enclosure that holds the flow generator rotates relative to the gravity G. Thus, this module insures that the gas flow is always directed along a direction opposite to the gravity, with the inlet module 202 being located below the exhaust module 208. In one embodiment, the orientation control module 210 can be a ball joint mechanism having a ball 300 that is free to move within a socket 310, as shown in Figure 3. The ball 300 is attached with an arm 302 to a wall of the tank/enclosure while the socket 310 is attached with a corresponding arm 312 to the flow generator. However, any other mechanical system may be used as the orientation control module 210 as long as the system allows the autonomous vertical positioning of modules 202 to 208 with relative to the gravity.

[0031] In another embodiment, an additional layer of protection is added to ensure that the outlet module is maintained vertically above the inlet module. In this embodiment, as illustrated in Figure 4, the centers of mass CMi to CIVU for each of the inlet, measuring, heating, and output modules are located on the axis of symmetry SA of these modules. In this or another embodiment, it is possible that the combined center of mass CM of these four modules is located closer to the inlet module 202 then to the outlet module 208, to ensure the correct positioning of the flow generator relative to the vertical direction, regardless of the tilt of the host enclosure (i.e., tank 214).

[0032] The flow generator discussed above can be used in any transportation device or in stationary systems. It can generate a flow of gases under any pressure in the range of 100 mbar to several bars. For example, the flow generator can be used with an aircraft having potentially flammable spaces, for monitoring the flammability of the gas. It can also be installed in shipment containers, used for transportation by boat or truck, of potentially hazardous chemicals. Depending on the application, the global size of the flow generator can vary from 1 cubic centimeter to 5 x 10³ cubic centimeters. Figure 2A shows a schematic of the flow generator 200 installed in a quiescent enclosure 214, without a measurement system, e.g., sensor 205, installed therein. Any measurement system and any control strategy can be used with the flow generator 200.

[0033] A specific implementation 500 of the flow generator 200, which is utilized for gas flammability measurements inside a fuel tank, is illustrated in Figure 5. The inlet module 202 is implemented in this embodiment as a stainless-steel tube 502 having a 2 cm inner diameter d1 and 4 cm outer diameter d2. The tube 502 is equipped with a flame arrester (e.g., including a stack of perforated plates) 504 at the upstream end. Note that the downstream direction D in this figure is opposite to the gravity G. A fluidic diode valve (e.g., having a truncated elongated ovoid profile) 506 is fixed by three pillars 508 at the entrance of the tube 502. The fluidic diode valve 506 acts on a gas flow as a diode acts on an electrical current, i.e. , allows the gas flow in only one direction. In this case, the fluidic diode valve 506 allows the gas flow 510 to move only downstream, along direction D.

[0034] The measuring module 204 may be formed within the same body 501 as the inlet module 202. In this embodiment, the body 501 of the flow generator 500 is made from steel and also serves as the body for all the other modules. In other words, the body 501 may be a same body for all the modules, meaning that the modules are integrally formed together. The size and shape of the parts of the body that correspond to the various modules may vary, as also shown in Figure 5.

[0035] The measuring module 204 may have its internal bore shaped as a truncated cone 503, to expand the inner diameter d1 of the entrance tube to another diameter d3, for example up to 3 cm. One or several flammability sensors 205 are installed inside the measuring module 204. A flammability sensor or detector is a sensor configured to detect and respond to the presence of a flame or fire. In one embodiment, the sensor only detects a concentration of a flammable material that is mixed with air. Any kind of flammability sensor may be used. In this embodiment, the flammability sensor 205 is an ionic probe, but other type of sensors may be used. It is noted that the power source 234 for the sensor and the controller 230 that receives the readings from the sensor are shown in this embodiment being located outside the tank 214 (the tank is only partially shown in the figure). One or more wires 235 may be used for connecting the power source 234 to the sensor 205 and to the heater element 520. Similar wires (not shown) may be used for connecting the controller 230 to the sensor 205 for receiving its readings. In one embodiment, the communication between the controller 230 and the sensor 205 may be implemented in a wireless manner. The controller 230 may also be configured to control the power source 234, i.e., to determine when to supply power to the sensor and to the heating element. As discussed above with regard to Figure 2A, the controller and the power source can be attached to the body of the flow generator 500, can be remotely located from the flow generator and from the tank, or can be distributed on the body and away from the body.

[0036] The heating module 206 in this embodiment is implemented as a resistance element 520 that is flush mounted within the inner surface 522 of the heating module 206. However, the resistance element 520 may be formed deeper within a wall of the heating module 206, or even inside the bore of the heating module 206, as illustrated with a dash line. In this embodiment, the inner surface 522 is parallel to the symmetry axis SA. The resistance element 520 is electrically connected to a DC power supply (e.g., power source 234) that is capable of delivering up to 60 W of electric power. Alternatively, the power supply may be alternate current AC. If a precise control of the gas 216’s temperature is desired inside the heating module 206, a thermocouple 524 may be installed in the heating module for measuring the gas’s temperature. The thermocouple 524 may be electrically connected to the power supply 234 and in communication with the controller 230.

[0037] The exhaust module 208 may include two parts, a first part that is shaped as a truncated cone 526, which reduces the inner section from a diameter of d4 of about 3 cm (which may be the same as diameter d3) to a diameter d5 of about 2.5 cm, followed by the second part, which is shaped as a straight tube 528 of 2.5- cm inner diameter. The straight tube 528 may be equipped with a flame arrester (e.g., a stack of perforated plates) 530, which may be identical to the flame arrester 504. The exhaust module 208 is also formed in the body 501 of the flow generator 500.

[0038] All these modules are attached to the orientation control module 210 by a filamentary rigid metallic structure 540 (a holder) formed in stainless-steel. In this embodiment, the overall dimensions of the body 501 of the flow generator 500 are those of a cylinder having an external diameter of about 4 cm and a length of about

11 cm. The cylinder has a bore that extends throughout the body and has various internal diameters d1 to d4, as discussed above. The dimensions of the body 501 are dictated by the hosted measurement system, which requires a minimal volume of 20 cm³ for an ignition kernel to develop at 200 mbar of ambient pressure. However, these dimensions would change depending on which type of sensor 205 is used, what gases need to be measured, what is the ambient pressure of these gases, etc. [0039] A method for operating the flow generator 200 or 500 is now discussed with regard to Figure 6. The method includes a step 600 of installing the flow generator 200 or 500 inside the tank 214. The orientation control module 210 is fixed on a wall of the tank in such a way that modules 202 to 208 are stabilized in a vertical direction, along the gravity G, with a downstream direction D being opposite to the gravity G, as illustrated in Figures 2 and 5. In step 602, the heating module 206 is powered on, for example, by an adjustable low voltage DC power supply (e.g.,

12 V, 5A max). The heating module 206 may be powered manually, by the operator of the tank, or automatically, by the controller 230 that controls the flow generator 200 or 500. In one application, the power supply 234 is installed outside the tank 214, as illustrated in Figure 5. If, for example, multiple flow generators are used in different compartments, a single DC power supply may be used for all of them. [0040] In step 604, a gas flow through the flow generator achieves a steady state. The time necessary for achieving the steady state depends on the size of the flow generator, and the time can be from a few seconds to a few minutes. Depending on the measurements to be performed, a speed of the gas flow is adjusted in step 606, with the controller 230, to be a constant flow or a modulated flow. The constant flow generates the same volume flow per unit time per cross-section while the modulated flow generates a varying volume flow per unit time per cross-section. The constant flow is achieved by the controller 230 by controlling the power source to provide electrical energy to the heating element 520 to generate constant heating, while the modulated flow is achieved by the controller 230 by controlling the power source to provide electrical energy to the heating element 520 to generate a varying heating. In the case of an electric heater 520, this step can be achieved by modulating the electrical current provided by the power source 234 to the heater. The controller can be configured to apply any desired modulation to the electrical current supplied to the heating element. If the thermodynamic conditions inside the tank or flow generator or the gas composition inside the flow generator 200 or 500 evolves, the flow in the flow generator can be adjusted by controlling in step 606 the energy supplied to the heating module 206. [0041] The sensor 205 reads one or more parameters associated with the gas flowing through the bore of the flow generator, and provides that parameter to the controller 230. The controller 230 analyzes in step 608 the one or more parameters and generates a reading indicative of those parameters, which is then presented to the user of the flow generator or to a remote sensor. The parameter can be a concentration of a gas, a type of a gas, etc. In step 610, the controller 230 turns off the flow generator by turning off the electrical energy supplied to the heating module 206. After same time (depending on the size of the flow generator, between a few seconds and a few minutes), the flow completely stops and the gas 216 becomes quiescent again.

[0042] Currently, the most common way to generate gas flows for measurements of gas properties in quiescent environments is by using small fans or pumps. These electrical devices are relatively complex and heavy compared to a large variety of sensors. In addition, these devices have moving parts (e.g., propellers), that require regular maintenance, especially in corrosive, humid or dusty environments. In addition, for installation in potentially flammable environments, defective electrical motors can increase the ignition hazard, as they can produce electric sparks.

[0043] An alternative solution is to use ionic wind devices that are able to generate gas flows in any direction, without any moving parts. However, they require the use of high-voltage sources (typically several kilovolts). These high voltages are prone to generate electro-magnetic interferences, which are undesirable. [0044] The flow generator 200/500 discussed above is technically simpler that the traditional approaches, more safer, and more inexpensive. The flow generators discussed above are lighter, more robust, and easier to install in challenging environments for which moving parts or high-voltages are not acceptable. Although the volume flow rate is relatively small for the embodiment discussed with regard to Figure 5, it is appropriate for gas analysis that generally does require large-scale flows in the quiescent enclosure. Alternatively, the sizes of the flow generator 500 can be scaled up to increase the gas flow.

[0045] The disclosed embodiments provide a flow generator having no moving parts, it is safe for generating measurements inside flammable materials, and is configured for generating the gas flow no matter of the change in the orientation of the tank that holds the gas to be measured. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0046] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. [0047] This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

Claims

WHAT IS CLAIMED IS:

1 . A gas flow generator (200, 500) for generating a gas flow in a quiescent volume, the gas flow generator comprising: an inlet module (202) configured to receive a gas (216); a measuring module (204) configured to measure a parameter associated with the gas (216); a heating module (206) configured to heat the gas (216); an outlet module (208) configured to discharge the gas (216) outside the gas flow generator (200, 500); and an orientation control module (210) configured to attach the outlet module (208) to a tank that holds the gas (216), wherein the orientation control module (210) is further configured to maintain the inlet module (202) below the outlet module (208) relative to a gravity direction G.

2. The gas flow generator of Claim 1 , wherein the measuring module is above the inlet module with regard to the gravity direction, and the heating module is above the measuring module with regard to the gravity direction.

3. The gas flow generator of Claim 1 , wherein the heating module is above the inlet module with regard to the gravity direction, and the measuring module is above the heating module with regard to the gravity direction.

4. The gas flow generator of Claim 1 , wherein the inlet module includes a fluidic diode valve that prevents a backflow of the gas.

5. The gas flow generator of Claim 1 , wherein the measuring module includes a sensor that directly contacts the gas and is configured to measure the parameter.

6. The gas flow generator of Claim 1 , wherein the heating module includes a heating element for heating the gas.

7. The gas flow generator of Claim 1 , wherein an orientation of the inlet, measuring, heating and outlet modules make the gas to flow from the inlet module toward the outlet module, against the gravity.

8. A gas flow generator system (500, 214) for generating a gas flow (510), the gas flow generator system comprising: a tank (214) having a housing (212) configured to hold a gas (216); a gas flow generator (200, 500) located inside the housing (212) and configured to generate the gas flow (510) and measure a parameter associated with the gas (216); and an orientation control module (210) configured to attach the gas flow generator (200, 500) to the housing (212), wherein the orientation control module (210) is configured to hold the gas flow generator (200, 500) in a same orientation relative to a gravity direction G when the tank (214) changes an orientation relative to the gravity direction G.

9. The gas flow generator system of Claim 8, wherein the gas flow generator comprises: an inlet module (202) configured to receive the gas (216); a measuring module (204) configured to measure the parameter associated with the gas (216); a heating module (206) configured to heat the gas (216); and an outlet module (208) configured to discharge the gas (216) outside the gas flow generator (200, 500).

10. The gas flow generator system of Claim 9, wherein the measuring module is above the inlet module with regard to the gravity direction, and the heating module is above the measuring module with regard to the gravity direction.

1 1 . The gas flow generator system of Claim 9, wherein the heating module is above the inlet module with regard to the gravity direction, and the measuring module is above the heating module with regard to the gravity direction.

12. The gas flow generator system of Claim 9, wherein the inlet module includes a fluidic diode valve that prevents a backflow of the gas.

13. The gas flow generator system of Claim 9, wherein the measuring module includes a sensor that directly contacts the gas and is configured to measure the parameter.

14. The gas flow generator system of Claim 9, wherein the heating module includes a heating element for heating the gas.

15. The gas flow generator system of Claim 9, wherein an orientation of the inlet, measuring, heating and outlet modules makes the gas to flow from the inlet module toward the outlet module, against the gravity.

16. The gas flow generator system of Claim 9, further comprising: a power source configured to supply electrical power to the heating module; and a controller configured to control the electrical power supplied to the heating module to modulate a heat amount supplied to the gas.

17. The gas flow generator system of Claim 9, wherein a center of mass of the inlet, measuring, heating, and outlet modules is closer to the inlet module than to the outlet module.

18. The gas flow generator system of Claim 9, wherein center of masses of the inlet, measuring, heating, and outlet modules are located on an axis of symmetry of the gas flow generator.

19. A method for generating a gas flow with a gas flow generator (500), the method comprising: attaching (600) the gas flow generator (200, 500) to an interior wall of a tank (214), wherein the tank (214) holds a static gas (216); turning on (602) the gas flow generator (200, 500) by generating heat inside the gas flow generator (200, 500); generating (604) a steady-state gas flow through the gas flow generator (200, 500); adjusting (606) a speed of the gas flow; measuring (608) a parameter of the gas (216) that flows through the gas flow generator (200, 500); and turning off (610) the heat generated inside the gas flow generator to stop the flow of the gas.

20. The method of Claim 19, wherein the step of adjusting comprises: modulating a speed of the gas flow.