This invention relates to devices that condition fluid flow within a conduit. More specifically, the invention pertains to a fluid flow conditioning apparatus having self-adjusting cojoined tab members that reduce flow losses within a conduit.
As dependency on fossil fuels decreases, share of renewable energy sources—such as solar and wind—for power generation is growing. However, weather changes can cause fluctuations in renewable energy generation, strongly affecting reliability and availability of the renewable energy source. Thus, effective and efficient energy storage systems are key to optimal utilization of renewable energy sources.
To counter intermittency and expand capacity of renewable solar energy resource for power generation, energy storage systems with easy grid integration are necessary. Thus, the need for long-term energy storage systems is increasing. Large energy storage systems help to stabilize the power grid by compensating for the energy generation fluctuations in real-time. Latent Heat Based Thermal Energy Storage (LHTES) systems can offset energy fluctuations experienced by the power grid. For this reason, there is an avid interest among researchers for inventing way to decrease material usage, increase energy density, and reduce cost with respect to LHTES system.
Research shows that LHTES systems suffer from two major drawbacks. Firstly, non-uniform and slow charging rate of the energy storage capsules leads to higher heat losses. Secondly, increase in the pressure drop introduced in the flow conduit in the upstream section of the system contributes to the lowering and slowing down of the heat transfer from the heated airflow to the energy storage material within a tank. One of the key reasons for the decrease in the energy efficiency of the system is presence of fluid flow irregularities found in the upstream lengths of the tank due to a bend in the flow channel.
Currently known flow-conditioning devices, such as the one disclosed in US Pat. Pub. No. 2014/0338771, produce significant pressure drops when positioned in the flow channel, causing the fluid flow profile to resemble that of laminar flow. This fluid flow profile has high velocity heads in the center, thus making the flow profile uneven. Furthermore, these prior art devices develop a more parabolic and a less dispersed velocity profile—and, as a result, they exhibit decreased rate of heat transfer and charging of the system.
Controlling the flow of the heat transfer fluid through a heat exchanger with least possible expenditure of energy, while reducing maintenance requirements and extending life of the system is essential. Failing to control flow characteristics for the heat exchanger application leads to slow and uneven charging, reduced energy storage, damage caused due to corrosion and decrease in total system life. For efficient and productive operation, heat exchangers applications require stable upstream flow profiles in the fluid conduits before the heat transfer fluid enters the heat exchanger. Irregular and uneven flows at reduced pressures often result in decreased overall energy efficiency of the system and, thus, affect the rate and uniformity of the charging of the thermal energy storage.
Presence of inline elbows, which are commonly used to reduce straight pipe runs, due to space restrictions, result in generation of swirl and distortion in the velocity profile of the fluid flow within a pipeline. Flow distortion create pressure changes in the system, reducing the net positive thermal energy gain. If not corrected, these flow distortions result in excess noise and system erosion, which lead to reduced life of heat exchanging tubes. An inline elbow flow conditioner can be installed upstream from the heat exchanger to ensure an optimal flow profile, for heat exchanger's its efficient operation. Flow profile distortions such as swirl, asymmetry, and non-flatness can be isolated in the pipeline to give rise to more repeatable, symmetrical and relatively flat flow profiles with minimal losses in pressure.
Generation of more benign operating environments by providing conditioned flow streams entering at the inlet of the heat exchanger in an equally distributed pattern and uniformity enables in increasing the system life, reducing maintenance cost, noise, and risks to corrosion. Heat exchangers are adversely affected by flow disturbances occurring upstream of the flow conduit. Many flow conditioning applications are not designed with straight-run piping, for example, because of the imposed space constraints.
Therefore, what is needed is a novel flow conditioning apparatus configured to enhance and improve heat transfer characteristics for the system designed for high temperature heat exchanger applications, such as LHTES systems.
The problem stated above is now resolved by a novel and non-obvious fluid flow conditioning apparatus. In an embodiment, the fluid flow conditioning apparatus includes a first tabular member having a first leading edge, a first trailing edge, a first outer surface, and a first inner surface and a second tabular member having a second leading edge, a second trailing edge, a second outer surface, and a second inner surface. The leading edges of the first and the second tabular members are cojoined. When the conjoint tabular members are placed into a fluid flow, an angle between the first tabular member and the second tabular member is configured to decrease in response to increasing a Reynold's number of the fluid flow. Likewise, the distance between the first trailing edge of the first tabular member and the second trailing edge of the second tabular member is also configured to decrease as the Reynold's number of the fluid flow increases. In this manner, the cojoined tubular members are configured to adjust the shape of their collectively assembly based on the characteristics of the fluid flow—specifically, the static and dynamic pressure.
In an embodiment, the first and the second tabular members can be made of an elastomeric material, for example a hyperplastic material. The elastomeric material is configured to undergo an elastic deformation in response to a dynamic pressure of the first fluid flow being exerted onto the outer surfaces of the cojoined tabular members. In this manner, the elastic deformation of the elastomeric material reduces a drag coefficient of the cojoined tabular members. Furthermore, flexible tabular members can be configured to exhibit flapping in response to changes in dynamic pressure of the fluid flow. This flapping behavior of the tabular members generates vortices in the downstream fluid flow, thereby increasing intermixing thereof.
In an embodiment, the first tabular member and the second tabular member can be cojoined via a hinge. The hinge can biased, such that the pressure exerted onto the outer surfaces of the tabular members by fluid flow partially closes the hinge against the biasing force. The biasing force is configured at least partially open the hinge in response to a reduction in the pressure exerted onto the tabular members by the fluid flow. Furthermore, a biasing element—such as a spring—may be disposed at the hinge or between the cojoined tabular members. The biasing element biases the hinge toward an open configuration. In this embodiment, the pressure exerted onto the tabular members by the fluid flow at least partially closes the hinge against a biasing force of the biasing element. Furthermore, when tabular members are cojoined via a hinge, the tabular members may be flexible or rigid. In the case the tabular members are rigid, the will generate tip vortices in a downstream fluid flow, thereby increasing intermixing thereof.
The cojoined tabular members described above can be affixed to an insertion plate-type flow conditioner. In an embodiment, fibrous structures can disposed within apertures of the insertion plate-type flow conditioner, such that the fibrous structures will facilitate creation of eddies within a downstream fluid flow.
For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:
In the following detailed description of the preferred embodiment, reference is made to the accompanying drawings, which form a part hereof, and within which specific embodiments are shown by way of illustration by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.
Definition Of Parameters
Horizontal and vertical flatness efficiency parameters have been defined to quantify the flatness of the flow profile, which is the difference between the fully developed and distorted flow profile for a flow conditioning system. Parameters σh and σv represent deviation in the effective flow profile of conduit 18. In the Table 1 below, σh and σv were measured at a distance three times the length of the diameter of conduit 18 from the bend, with the fully developed flow profile.
Here, Uhref, Uvref and Uh, Uv are the fully developed axial velocities and effective velocities in vertical and horizontal plane respectively with the flow conditioning device.
Variables σhi(z)′ and σhi(z)″ represent values of flatness efficiency calculated for the same system configuration with and without flow conditioner 12, wherein the distance z is evaluated as z=0 (placed immediately after the disturbance causing element, here elbow). Therefore, these parameters measure the relative efficiency of the flow-conditioning device with respect to the system without flow conditioner as the distance z from the piping element varies. Here, z equals to the length that is 3 diameters from the bend. Therefore, higher is the efficiency parameter for the conditioner, greater is its flow conditioning performance relative to the system without flow conditioning.
Next, variable Ptr is used to represent the relative pressure drop. Pt0 (Eq. 2) is an area weighted average pressure at the inlet (Pt01) and at three diameters from the bend (Pt2), Refer
Relative Total Pressure Drop for the section defines how much total pressure energy is lost with respect the total inlet pressure energy.
As the value of the parameter Ptr approaches zero, the pressure drops across the measurement section decreases, which means that more total energy is available at the inlet of the energy storage tank.
Next, Table 1 provided below shows that by changing at least one of the angles between tabs 16, the fluid flow downstream from flow conditioner 12 can be further adjusted. In Table 1, σh and σv represent the horizontal and vertical flatness efficiency parameters, used to quantify flatness of the flow profile, which is the difference between the fully developed and distorted flow profiles.
The results in Table 1 illustrate that relative efficiency of the flow conditioning process of insertion type flow conditioner 12 has been found relatively low, as the performance of the flow conditioner 12 is dependent on the angle between tabs 16. In addition, reducing the angle of tab 16 in the region of higher velocities aids in development of flatter fluid flow profile. However, angles for other tabs 16 need to be adjusted simultaneously to optimize vortex shedding and achieve minimal pressure drops. This is impossible to achieve with prior art devices, such as those depicted in
Insertion Type Flow Conditioner Having Self-Adjusting Tabs
As the data explained above shows, although rigid, non-adjustable tabs 16 of an insertion plate-type flow conditioner 12 improve fluid flow profile, their performance can be further optimized by if the individual angles between cojoined tabs 16 could be adjusted independently of one another based on the local fluid flow properties, such as static and dynamic pressure. However, in prior art flow conditioners, tabs 16 are rigidly affixed to the plate 12 at non-adjustable angels.
This problem is now resolved by a novel and nonobvious invention, an embodiment of which is depicted in
As described above with respect to
As depicted in
If the characteristics of the upstream fluid flow change, angles 22 between each cojoined pair of tabs 20 will passively (without requiring any external input) readjust based on the instantaneous pressure the fluid flow exerts on each tab-pair 20 at that instance. Thus, if the velocity of the upstream fluid flow decreases, the static and dynamic pressure exerted onto tabs 20 by the fluid flow will also decrease—in which case, the tabs 20 will partially straighten, increasing angle 22 therebetween. Conversely, as the pressure of the upstream fluid flow increases, tabs 20 will bend more, decreasing angle 22 therebetween. These adjustments are achieved passively, based on the static and dynamic pressure of the fluid flow, without requiring any manual adjustment of tabs 20 or involvement of sensors and motors to actively control angles 22 therebetween. Furthermore, the trailing edges of tabs 20 can have a tapered—i.e., airfoil-like shape—to reduce the pressure drop as the fluid flow passes over the cojoined tabs 20.
In this manner, tabs 20 are configured to self-adjust in response to change in Reynold's number of the fluid around tabs 20. As the Reynold's number of the fluid flow increases, the dynamic pressure exerted by the fluid onto the surface areas of tabs 20 also increases, causing the tabs 20 to bend inwardly. As tabs 20 undergo elastic deformation angle 22 between them decreases. In this manner, each cojoined pair of tabs 20 achieves a configuration that offers minimal resistance to fluid flow, thereby decreasing the pressure drop through the flow-conditioning device 12. Furthermore, another advantage of flexible tabs 20 is that, when subjected to turbulent flow, they will “flap” in response to the dynamic pressure of the fluid flow, thus facilitating intermixing of the fluid downstream.
The properties of the material from which tabs 20 are made dictates the amount of elastic deformation that tabs 20 will undergo in response to the total pressure exerted by the fluid flow. The material will bend and tabs 20 will streamline themselves approaching a shape of an airfoil, thereby reducing the total resistance of cojoined tabs 20, and therefore, the drag forces that cojoined tabs 20 will experience from the fluid. Furthermore, elasticity of the material enables tabs 20 to exhibit flapping, which helps generate vortices to perform fluid intermixing.
In an embodiment depicted in
Yet another embodiment is depicted in
Additional Fluid Flow Conditioning Mechanisms
The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
This non-provisional patent application is a continuation of and claims priority to a U.S. Provisional Application No. 63/199,292 filed Dec. 18, 2020.
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Number | Date | Country | |
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63199292 | Dec 2020 | US |