Moving bed particle heat exchanger

Abstract

A particle heat exchanger includes: a housing comprising: an inlet located at the top of the housing; and an outlet located below the inlet, the housing being configured to enclose a heat transfer particle flow flowing downward from the inlet to the outlet within the housing; at least one heat transfer tube enclosed within the housing and in contact with the heat transfer particle flow therethere, each heat transfer tube extending substantially parallel to an axis extending between the inlet and the outlet of the housing; and at least one partition located between the inlet and the outlet of the housing, the at least one heat transfer tube extending through each partition, each partition including at least one opening configured to form at least one flow contraction in the heat transfer particle flow between the inlet and the outlet of the housing.

Description

[0001] Related citations

[0002] This application claims priority to Australian Provisional Patent Application No. 2019903064, filed on August 22, 2019, the contents of which are to be understood as incorporated herein by reference. Technical Field

[0003] This invention generally relates to a moving bed particle heat exchanger configured to transfer heat between a moving bed of heat transfer particles and a heat transfer medium. The invention is particularly suitable for transferring heat from solar-heated particles (heated by solar energy from a solar receiver) to a heat transfer medium, and will be described in conjunction with this exemplary application. However, it should be understood that the moving bed particle heat exchanger can be used in a variety of other heat exchange applications involving heat transfer between particles and another heat transfer medium, which may be a heat source or a radiator. Background Technology

[0004] The following discussion of the background of the invention is intended to facilitate understanding of the invention. However, it should be understood that this discussion is not an endorsement or acknowledgment that any material mentioned was disclosed, known, or was part of the general public knowledge at the priority date of this application.

[0005] Particle heat exchangers (PHX), typically comprising fluid (liquid / gas / multiphase media) / solid fluidized beds, have been developed for a variety of applications, including the petrochemical, mineral, food processing, paper, and power industries. Particle heat exchangers facilitate heat transfer between a flow of solid particles (typically a flow of fine particles fluidized in some way) and a flow of fluid (typically a liquid, gas, or multiphase heat transfer fluid). Using a flow of solid particles as the heat transfer medium offers advantages associated with the thermal and chemical stability of the heat transfer particles at elevated temperatures and their fluid-like behavior.

[0006] Particle-based heat transfer systems have recently been investigated as alternatives to molten salts for heat transfer media and thermal energy storage (TES) media in next-generation solar / thermal (CSP / T) systems. A significant advantage of particle-based heat transfer systems over molten salts is their ability to operate over a wide temperature range. Particles can achieve high temperatures (>700°C and in some cases even >1000°C) without decomposition or corrosion and can operate at “low” temperatures (<0°C) without phase change. In such systems (e.g., as...), Figure 1 As shown, fine particles are used to collect heat from a central receiver in a solar / thermal system, and then the collected heat is transferred to a heat transfer fluid via a particle heat exchanger. These advantages allow the heat transfer system to be designed to be more efficient than molten salt forms, and lead to the design of directly heated particle receivers, providing cost-effective TES options.

[0007] For this technology to be feasible, particle heat exchangers (PHXs) must be designed to efficiently transfer heat from hot fine particles to a heat transfer medium or vice versa. Many particle heat exchangers for this application have been previously studied and tested, including heat transfer from particles to a heat transfer fluid in a tube or parallel plate, and heat transfer through fluidized particle flow to a heat transfer fluid in a tube. Examples of these existing PHX designs include:

[0008] The moving bed tube PHX with a horizontal tube array studied in T. Baumann, S. Zunft, Energy Procedia (2015) 748-757. This design involves a cross-flow arrangement where hot, fine particles are gravity-fed from an upper supply point through vertically arranged pipes (above the horizontally oriented tube array). The particle flow impinges on the top of the tubes, thus creating a conical stagnation zone at the top of the horizontal tubes and a void zone below the horizontal tubes, significantly reducing the effective heat transfer area of ​​the tubes. Furthermore, the limitation of pipe size necessitates multiple manifolds / bends to connect the horizontal tube array for large-scale systems.

[0009] The gravity-fed counter-flow plate PHX, studied in K. Albrecht, C. Ho, Proc. ASME 11th Int. Conf. on Energy Sustainability (2017) ES2017-3377, comprises a plate heat exchanger configured in a counter-flow arrangement. Hot particles move downwards from the top section to the bottom section under gravity through spacing between parallel, diffusion-bonded microchannel plates containing the heat transfer fluid flow. Due to size limitations in manufacturing the microchannel plates, multiple manifolds must be used to connect them. To achieve a reasonable particle-side heat transfer coefficient, the spacing between the parallel microchannel plates is typically <3 mm. This can pose practical challenges in maintaining the narrow spacing as the microchannel plates thermally expand at elevated temperatures.

[0010] The hot sand fluidized bed PHX (referred to as "SandTES") studied in International Patent Publication WO2017210713A1 comprises a horizontal tube bundle carrying a heat transfer fluid immersed in a hot sand bed fluidized by hot air injected from the bottom, transferring heat from the hot sand to the heat transfer fluid in the horizontal tubes. Fresh hot sand can be added to the PHX by controlling an air cushion above the fluidized bed, allowing the fluidized bed to be transported horizontally through the PHX in the opposite direction to the flow of the heat transfer fluid. Due to mixing, the fluidized sand bed can achieve a high particle-side heat transfer coefficient. However, the horizontal coverage area (footprint) of this type of PHX needs to be large to accommodate the large horizontal flow of the fluidized bed. Therefore, this form of PHX is generally limited to ground-based installations. For solar / thermal (CSP / T) systems, this location will require an additional particle conveying system between the hot particle storage tank PHX and the cold particle storage tank, compared to the two previous gravity-fed PHX designs.

[0011] Therefore, it is desirable to provide a new or alternative particle heat exchanger (PHX) construction that addresses one or more of the shortcomings of previous PHX designs. Summary of the Invention

[0012] The present invention relates to a staged moving bed particle heat exchanger comprising one or more heat transfer tubes aligned with a generally vertically oriented axis.

[0013] This invention provides a particle heat exchanger, the particle heat exchanger comprising:

[0014] Housing, the housing comprising:

[0015] An entrance, located at the top of the housing; and

[0016] The exit is located below the inlet.

[0017] The housing is configured to surround a heat transfer particle flow that flows downward from the inlet to the outlet within the housing;

[0018] At least one heat transfer tube, the at least one heat transfer tube comprising a heat transfer medium, each heat transfer tube being surrounded within the housing and in contact with the heat transfer particle flow therein, each heat transfer tube extending substantially parallel to an axis extending between the inlet and the outlet of the housing; and

[0019] At least one partition is located between the inlet and the outlet of the housing, and at least one heat transfer tube extends through each partition. Each partition includes at least one opening, which is configured to form at least one flow contraction in the heat transfer particle flow between the inlet and the outlet of the housing.

[0020] The inventors have discovered that in a bounded particle flow domain with a constant cross-sectional area, the heat transfer particle flow becomes fully developed hydrodynamically and thermally once the particles travel further away from the inlet. It has been found that increasing the flow velocity does not alter the flow and heat transfer characteristics, and more specifically, does not change the mixing characteristics of the particle flow. The lack of mixing limits effective heat transfer from the particles to the heat transfer surface, where heat transfer occurs primarily from those particles very close to the heat transfer surface. Particles farther from the heat transfer surface transfer heat to the heat transfer tube (and any heat transfer medium therein) through the particle bulk located between the particle and the heat transfer surface.

[0021] Through modeling, the inventors surprisingly discovered that mixing in a solid particle flow can be generated by including at least one constriction in the solid particle flow. This constriction causes particles in the flow that are radially dispersed from the heat transfer surface to flow toward and through the constriction, thus remixing the particles in the flow as they flow toward and through the constriction. The constriction also generates turbulence in the flow without creating voids at the heat transfer boundary between the wall and the heat transfer particles. Heat transfer can be optimized by further introducing spaced-apart constrictions along the flow path of the solid particle flow, thereby creating particle flow "stages." These particle flow stages are generated by the constrictions within the separator. This forces the particle flow to remix at each flow stage. This also results in the renewal of the heat inlet region at the beginning of each stage. The separator also functions as a flow distributor (flow distribution plate) that divides the heat transfer particle flow into a series of short particle beds.

[0022] The axial (usually vertical) orientation of the heat transfer tubes within the shell, between their top inlet and bottom outlet, also ensures that the particle flow can completely surround each heat transfer tube within the shell. Unlike horizontally oriented tubes, there are no stagnation or void regions around the tubes because the heat transfer particles flow uniformly downwards and around the length of each heat transfer tube.

[0023] The particle heat exchanger of this invention thus solves three important problems of the previous PHX design:

[0024] • Make full use of the heat transfer tube surface for heat transfer (compared to using a horizontal tube array).

[0025] • Enhanced particle-side heat transfer by enabling continuous renewal of the heat inlet region and / or remixing of particles at each stage.

[0026] • Simpler and scalable granular heat exchangers with heat exchanger tube arrays (vertically oriented) for large-scale solar / thermal system (CSP / T) applications reduce the need for manifolds or bends.

[0027] It should be understood that, in the preferred embodiment, the heat transfer particles are heated by solar energy from a solar receiver. However, the invention is not limited to this application, and the heat transfer particles can be heated by alternative heating sources, such as electric heating.

[0028] The shell of a particle heat exchanger is typically designed as a housing for heat transfer tubes and a flow of heat transfer particles surrounding and flowing downward along these tubes. In many embodiments, the shell is configured to guide the flow of heat transfer particles vertically downward from the inlet to the outlet. In these embodiments, the heat transfer particles are contained within cavities or internal spaces defined / confined between the walls of the shell, wherein the shell is designed to guide the flow of heat transfer particles downward from the inlet to the lower outlet in stages defined by each of the partitions. It should be understood that the shell can have any desired shape and configuration. In some embodiments, the shell has a polygonal cross-section, preferably a regular polygon, such as a rectangle or square. In other embodiments, the shell is cylindrical.

[0029] The heat transfer tubes are typically oriented vertically within the shell. In this sense, the axis between the inlet and outlet preferably defines a vertical axis. This typically requires that the heat transfer tubes and the axis be aligned vertically relative to the ground on which the granular heat exchanger is located. "Upper" and "lower" should also be understood as relating to the axis, where "upper" or "above" means axially located above or above a given feature relative to the axis extending between the inlet and outlet of the shell, and "lower" or "downward" means axially located below or below that feature.

[0030] The heat transfer particle flow typically flows from the inlet of the casing towards the outlet. The outlet is located below the inlet of the casing, so the heat transfer particle flow is generally oriented downwards relative to the inlet of the casing. In many embodiments, this flow direction allows the heat transfer particle flow to be driven by gravity.

[0031] The size of the flow contraction opening in each separator is designed to remix the particles as they flow toward and pass through the contraction. The specific size and configuration of this opening are typically designed to suit a particular solid particle supply (with different sizes and properties), heat exchange application, and heat exchanger configuration. Generally, the at least one opening in the separator is configured to cause the heat exchange particle flow to contract by at least 20% of the cross-sectional flow area within the housing, preferably between 20% and 80%. In some embodiments, the flow contraction may be at least 60% of the cross-sectional flow area within the housing, preferably at least 70%.

[0032] The flow contraction opening can have various configurations. In many embodiments, the flow contraction opening includes an orifice located near, preferably around, the intersection of each of the heat transfer tubes with each partition. The opening can include an annular opening, preferably a circular annular opening, surrounding the intersection of each of the heat transfer tubes with each partition. The size of the opening provides an annular gap through which heat transfer particles can flow. The size of this annular gap can be customized or trimmed to provide a specific flow volume through each stage and throughout the particle heat exchanger. The size of the annular gap can also be varied to modify the characteristics of the heat inlet region renewal at the beginning of each stage. Each opening may also include at least one arm extending from the partition to the heat transfer tube, the at least one arm being configured to position the heat transfer tube within each opening. These arms form tube support elements in the partition for positioning and holding the heat transfer tube in place within the housing. The arms can be configured to accommodate the thermal expansion of the heat transfer tube. The arms may include any flanges, ribs, or other protrusions extending radially from the partition to position and preferably engage with the outer surface of the heat transfer tube located in the flow contraction opening. However, it should be understood that in alternative embodiments, each heat transfer tube may include one or more arms, flanges or ribs extending into the flow contraction opening to perform the same function as the arms extending from the separator.

[0033] The heat transfer tube may include any suitable heat transfer medium or arrangement capable of transferring heat from the heat transfer particles. In some embodiments, the heat transfer medium includes a fluid, preferably a heat transfer fluid. In some embodiments, the heat transfer medium includes heat transfer particles or a multiphase arrangement. In some embodiments, the heat transfer medium may include endothermic chemical processes, etc. In some embodiments, the heat transfer medium includes a solid medium involving or not involving a heat transfer medium flow, such as a heating element, or a reaction involving a solid catalyst and reactant / product gases.

[0034] In an exemplary embodiment, the heat transfer medium comprises a heat transfer fluid flowing through at least one heat transfer tube. Each heat transfer tube is enclosed in a housing and extends substantially parallel to an axis extending between the inlet and outlet of the housing. In these embodiments, the invention provides a particle heat exchanger comprising:

[0035] Housing, the housing comprising:

[0036] An entrance, located at the top of the housing; and

[0037] The exit is located below the inlet.

[0038] The housing is configured to surround a heat transfer particle flow that flows downward from the inlet to the outlet within the housing;

[0039] At least one heat transfer tube through which a heat transfer medium can flow, each heat transfer tube being enclosed within the housing and in contact with the heat transfer particle flow therein, each heat transfer tube extending substantially parallel to an axis extending between the inlet and the outlet of the housing; and

[0040] At least one partition is located between the inlet and the outlet of the housing, and at least one heat transfer tube extends through each partition. Each partition includes at least one opening configured to form at least one flow constriction in the heat transfer particle flow between the inlet and the outlet of the housing.

[0041] The flow of the heat transfer fluid within the heat transfer tubes can be in any suitable direction relative to the heat transfer particle flow. In some embodiments, the flow is in a parallel flow direction relative to the heat transfer particle flow. In other embodiments, the flow of the heat transfer fluid is in a counter-flow direction opposite to the heat transfer particle flow. Mixing of parallel and counter-flow is also possible in particle heat exchangers that include multiple heat transfer tubes.

[0042] The particle heat exchanger of the present invention may include a heat transfer tube. However, embodiments of the heat exchanger of the present invention preferably include at least two heat transfer tubes, and more preferably multiple heat transfer tubes, which are laterally spaced within the housing. Using multiple heat transfer tubes and / or multiple modular housings connected in parallel, including multiple heat transfer tubes, increases the heat exchange capacity of the device. Here, the heat transfer tubes are preferably arranged in a vertical tube array within the housing or each housing.

[0043] In many embodiments, each heat transfer tube comprises a substantially linear cylindrical tube. Each heat transfer tube is constructed of a thermally conductive material. Specific construction materials are typically selected to suit the operating temperature range of the heat exchanger and the desired chemical compatibility between the heat transfer particles and the heat transfer fluid. Examples of suitable materials include metals, ceramics, carbides such as stainless steel, nickel-based alloys, alumina, silicon carbide, and graphite. Specific examples include stainless steel (316, Sandvik 253MA) and nickel-based alloys (Haynes 230, Haynes 207, Inconel 617, Inconel 625, Inconel 800H, Inconel 740H). However, it should be understood that other construction materials may be used depending on the specific application, and the invention is not limited to the materials described above.

[0044] The particle heat exchanger of the present invention can be configured to include any number of particle bed stages or phases. Therefore, the particle heat exchanger may include only one separator, but preferably includes two or more separators spaced apart between the inlet and outlet of the housing along the length of each heat transfer tube. Depending on the available size of the heat exchanger and the specific heat transfer application, any number of separators may be used between the inlet and outlet of the housing, such as three, four, six, ten, etc. Each separator preferably includes a planar element radially oriented relative to the axis extending between the inlet and outlet to divide the housing into at least two separate solid particle flow chambers. This planar element typically comprises a plate or plate.

[0045] The shell of a particle heat exchanger can take various forms. In some embodiments, the shell comprises a container with an internal space that surrounds all the heat transfer tubes within that internal space. In these embodiments, the shell surrounds multiple heat transfer tubes. Here, the heat transfer particle flow is within a common space (flow volume). In other embodiments, the shell comprises multiple spaced-apart solid flow conduits, each having an inlet and an outlet, and each containing a heat transfer tube extending therein. In these embodiments, the shell comprises multiple separate outer shells, each surrounding a subset of all the number of heat transfer tubes. In some embodiments, each spaced-apart solid flow conduit contains a single heat transfer tube. Here, the shell may comprise multiple spaced-apart containers, each containing a heat transfer tube. Each spaced-apart container preferably comprises an elongated tube extending coaxially around each heat transfer tube.

[0046] In other embodiments, the housing includes a mounting body having a plurality of spaced-apart shafts through which heat transfer tubes extend, each shaft having a diameter larger than the outer diameter of the heat transfer tubes extending therethrough. The mounting body preferably comprises a block. The housing typically includes at least two stacked mounting bodies, with each spacer located between adjacent stacked mounting bodies. In this way, the spacers can be inserted between the mounting bodies and function as described above.

[0047] Mixing of the particle flow (particularly at or near flow contractions) can be enhanced by including at least one fluidizing gas device located at or near the contraction, preferably supplied with gas using spacers for the channel. The fluidizing gas device is preferably configured to generate locally fluidized particle bubbles at the contraction. This enhances local mixing at and near each contraction.

[0048] In some embodiments, mixing of the particle flow can be enhanced by including at least one helical insert extending around at least one heat transfer tube. Similarly, including at least one radial element (e.g., rib, flange, fin, etc.) extending radially from the surface of at least one heat transfer tube into the housing can enhance mixing of the heat transfer particle flow. In some embodiments, the fins include longitudinal fins extending along at least a portion of the length of the heat transfer tube. In some embodiments, the radial element (e.g., rib or fin) extends circumferentially around the heat transfer tube. The radial element is preferably longitudinally spaced from the spacer at a position prior to the spacer along the length of the heat transfer tube relative to the direction of the heat transfer particle flow. Adding a radial element extending from the heat transfer tube prior to the flow contraction formed by the spacer can enhance particle mixing, which can result in complete renewal of the heat inlet region in subsequent stages.

[0049] Fins can be attached to heat transfer tubes or multiple heat transfer tubes in any suitable manner. For example, if the heat transfer tubes are metal, each fin can be welded to the heat transfer tube. Fins can be used as an additional device to increase the residence time of particles and also generate axial and rotational particle flow patterns to enhance mixing and increase the heat transfer area.

[0050] A variety of different heat transfer particles can be used in the heat exchanger of the present invention. Typically, the heat transfer particles usually comprise solid particles, and in some cases, are solid particles. The heat transfer particles can comprise any suitable endothermic fine particulate material, thus containing a large number of particles / microparticles. In some embodiments, the heat transfer particles comprise ceramics, preferably alumina-based ceramics. In embodiments, the heat transfer particles comprise a ceramic support comprising 75% Al₂O₃, 11% SiO₂, 9% Fe₂O₃, and 3% TiO. However, many other materials can be used. For example, the heat transfer particles can comprise various types of sand, including silica-based granular microparticles and / or calcium carbonate granular microparticles. However, it should be understood that granular or microparticle solid materials can be used.

[0051] The size of the heat transfer particles depends on the specific application. However, in many cases, the average particle size of the heat transfer particles is from 100 μm to 800 μm, and in some cases from 200 μm to 500 μm. In a particular embodiment, the heat transfer particles will preferably have an average particle size of about 300 μm.

[0052] It should be understood that heat transfer fluids can include any heat transfer liquid or gas suitable for a specific heat transfer application and conditions. In this respect, heat transfer fluids are selected to suit a specific heat transfer temperature range, pressure, and application. For example, supercritical carbon dioxide can be used as a heat transfer fluid for solar energy utilization (solar / thermal systems). In thermoelectric or process waste heat applications, steam, nitrogen, carbon dioxide, air, or other process gases can be used as heat transfer fluids. In other applications, heat transfer fluids can include molten salts. It should be understood that the heat transfer fluid side can also be used for causing another particle to flow, any phase change (such as boiling), chemical reactions including solid catalysts and gases, or heating elements that require heat transfer from / to heat transfer particles.

[0053] The granular heat exchanger of the present invention is particularly used as a heat exchanger in a solar / thermal system, preferably a heat exchanger in thermal communication with the solar receiver of the solar / thermal system. However, it should be understood that other applications are also possible. For example, the granular heat exchanger of the present invention can be used in the following non-limiting applications:

[0054] • Solar energy utilization at elevated temperatures above 700°C involves the use of fine particles as heat transfer fluids and thermal energy storage media. In the proposed PHX design, heat can be efficiently transferred from the thermal particles to the heat transfer fluid in the power block or processing loop to meet demand.

[0055] • This invention can be applied to a variety of applications that require particles as a thermal storage medium. Due to the chemical and thermal stability of the particles, this invention can be used in processes ranging from low temperatures (such as steam generation systems) to very high temperatures (such as chemical reaction systems).

[0056] • The full benefits of this invention can be obtained from any thermal process, regardless of the state or type of the heat transfer fluid, based on the consideration that this invention provides enhanced heat transfer on the particle side and that particle-side heat transfer primarily controls the overall heat transfer rate of the particle heat exchanger. Attached Figure Description

[0057] The invention will now be described with reference to the accompanying drawings, which illustrate specific preferred embodiments of the invention, wherein:

[0058] Figure 1 A schematic diagram of a solar / thermal system is illustrated, showing the position of a particle heat exchanger according to an embodiment of the present invention when it is positioned in thermal communication with the solar receiver of the system.

[0059] Figure 2 A schematic diagram of a multi-stage tubular particle heat exchanger with a vertical tube array configuration and multiple flow distribution plates is shown, illustrating (A) a front cross-sectional view and (B) a top view of the flow distribution plates.

[0060] Figure 3 A schematic diagram of a fluidized multistage tubular particle heat exchanger with a vertical tube array configuration and multiple flow distribution plates is shown, illustrating (A) a front cross-sectional view and (B) a top view of the flow distribution plates.

[0061] Figure 4 A schematic diagram of an annular flow tube particle heat exchanger with stacked ceramic blocks and tube support plates is shown, illustrating (A) a front cross-sectional view and (B) a top view of the ceramic blocks with tube support plates.

[0062] Figure 5 A schematic diagram of a multi-stage tubular particle heat exchanger with a vertical tube array configuration and multiple flow distribution plates including additional radial fins is shown, illustrating (A) a front cross-sectional view; and (B) an enlarged cross-sectional view showing the flow interruption function of the radial fins in a particle flow.

[0063] Figure 6 A schematic diagram of the parameters used for two-dimensional heat transfer modeling is provided.

[0064] Figures 7 to 10 The results of two-dimensional heat transfer modeling are provided, in the form of: for different distances between the particles and the wall (heat transfer surface) of the heat transfer tube (… d s ) and for different heat transfer tube lengths ( L hx ), heat transfer coefficient from body to wall ( h p With the particle bed velocity ( u p A curve that changes with the changes.

[0065] Figure 11 A schematic diagram of the parameters used for two-dimensional heat transfer modeling of a staged moving bed is provided.

[0066] Figure 12 The results of a two-dimensional heat transfer modeling of a staged moving bed are provided, in the form of: bulk-to-wall heat transfer coefficient ( h p With the particle bed velocity ( u p A curve that changes with the changes.

[0067] Figure 13A A schematic diagram of a cold flow test bench for verifying particle flow through a staged particle heat exchanger according to an embodiment of the present invention is provided.

[0068] Figure 13B Examples are provided from Figure 13A A series of photographs showing the flow progression during a test run of the cold flow test bench.

[0069] Figure 14 A schematic diagram of a heat flow test bench for verifying the particle flow and heat transfer characteristics of a staged particle heat exchanger according to an embodiment of the present invention is provided.

[0070] Figure 15 Experimental results and heat transfer modeling are provided, in the form of: for single and staged particle heat exchangers, as particle bed velocity ( u p The heat transfer coefficient from the body to the wall () h p The curve of the function ). Detailed Implementation

[0071] This invention provides an alternative particle heat exchanger device configured to transfer heat from a stream of solid particles to a heat transfer medium flowing through a heat transfer tube. The particle heat exchanger is designed for use in solar / thermal systems to transfer heat from heat transfer particles heated by solar energy from a solar receiver to a heat transfer medium, such as a heat transfer fluid. However, it should be understood that the particle heat exchanger of this invention can be used in a variety of other heat transfer applications requiring solid particle heat transfer.

[0072] Figure 1 A schematic diagram of a solar / thermal system 100 is shown, illustrating the position of a particle heat exchanger 200 according to an embodiment of the invention, positioned in thermal communication with the system's solar receiver and thermal storage system 120. Figure 1 As shown, the solar / thermal system 100 includes four integrated areas:

[0073] 1. A solar field 110 consisting of an array of heliostats 112, which are effectively shaped reflective surfaces that reflect and concentrate solar energy toward a solar receiver 122 (see below). Each heliostat 112 is individually controlled to track the movement of the sun during the day and guide (reflect) solar energy to the solar receiver 122.

[0074] 2. A receiver and heat storage system 120, comprising a solar receiver 122 for receiving directional solar energy from a heliostat 112 and transferring that energy to a heat transfer medium (in this case, heat transfer particles). Heated heat transfer particles are supplied by gravity to a heat particle storage chamber (heat silo) 124, ready to be supplied by gravity to a heat exchanger 125 located below the heat silo 124. The heat exchanger 125 is configured to transfer heat from the heated heat transfer particles to the heat transfer medium. For the present invention, this heat exchanger is configured according to an embodiment of the particle heat exchanger 200 of the present invention. Details of the particle heat exchanger 200 of the present invention will be explained in more detail below. Cold heat transfer particles (those with a lower heat content (i.e., temperature) than the supplied heated heat transfer particles) exit the heat exchanger 125 and are supplied by gravity to a cold particle storage silo (cold particle silo) 126, where the particles are stacked until they are recycled back to the solar receiver 122 for heating. This recycling is performed using a particle lift 128 in the illustrated system. It is noteworthy that in the illustrated embodiment, the hot silo 124, heat exchanger 125, and cold particle storage silo 126 are vertically connected in series, and the heat transfer particles move gradually through these units by gravity. However, it should be understood that the configuration of the storage units (hot silo 124 and cold particle storage silo 126) and heat exchanger 125 will depend on the storage unit size. For example, in other embodiments, several heat exchangers 125 may be arranged in parallel and connected to the silo, particularly if the storage volume is sufficiently large.

[0075] 3. An electric power block 130, which includes a thermoelectric conversion system 132, which in the illustrated system includes a power turbine 133 that drives a generator 134, but may include any suitable power generation system. The power turbine 133 uses a heated heat transfer medium to drive the movement of the turbine.

[0076] 4. Power grid connection 140. This power grid connection 140 is connected to an external power grid at this geographical location to transmit the generated electricity from generator 134 to the external power grid.

[0077] The various components of the solar / thermal system 100 can have various configurations depending on the application, power requirements, and the technology used in the solar / thermal system 100. For example, the solar receiver 122 can have a variety of different configurations to heat the heat transfer particles therein. This invention relates to the receiver and the heat exchanger 125 component of the heat storage system 120, the embodiments of which are combined with… Figures 2 to 4 Examples and descriptions.

[0078] Figure 2 A first embodiment of the particle heat exchanger 200 according to the present invention is illustrated. Figure 2A front cross-sectional view of particle heat exchanger 200 is provided. Figure 2 (A) and top section ( Figure 2 (B) As shown in the figure, the particle heat exchanger 200 includes a particle flow space 210 that surrounds a vertical tube array 220 forming a plurality of spaced-apart heat transfer tubes (or pipes) 222. The heat transfer tubes 222 comprise elongated tubes with a desired wall thickness, constructed of a thermally conductive material, preferably a metal such as stainless steel or a nickel-based alloy. The heat transfer tubes 222 are parallel to... Figure 2 The axis XX shown extends vertically. The heat transfer tube 222 includes an inner cavity through which the heat transfer fluid 205 flows. In the illustrated embodiment, the heat transfer fluid 205 (also referred to as the working fluid) moves upward through the heat transfer tube 222, although not illustrated, the heat transfer tube 222 is connected to a header and a footer. Surrounding the heat transfer tube 222 is an array of particle flow spaces 210 containing heat transfer particles. Although not shown, the particle flow space 210 is defined by a housing comprising a container with an internal space that encloses all the heat transfer tubes 222 within the internal space. The heat transfer particles flow from the upper inlet 230 to the lower outlet 232. The heat transfer fluid 205 in the heat transfer tube 222 flows in a counter-current direction opposite to the flow of the heat transfer particles 207. Similarly, although not illustrated, it should be understood that the actual particle heat exchanger 200 is housed within a sealed housing, wherein the inlet and outlet of the heat transfer particle 207 and heat transfer fluid 205 sections are connected to a suitably designed fluid and particle supply manifold and outlet manifold that will guide the flow in the desired direction.

[0079] Therefore, the particle heat exchanger 200 includes a countercurrent arrangement of two heat transfer fluids: a heat transfer fluid 205 inside the heat transfer tube 222 and a moving bed 236 of heat transfer particles 207 that surround and fall along the outer surface of the heat transfer tube 222 under the action of gravity.

[0080] The heat transfer particles 207 comprise any suitable particles having a suitable specific heat capacity for the desired heating (in the receiver) and heat transfer application. The heat transfer particles 207 are typically solid particles or microparticles with an average particle size between 100 μm and 800 μm. In an exemplary embodiment, the microparticles have an average particle size of about 300 μm. The inventors selected ceramic heat transfer particles 207 (such as alumina-based ceramic particles) for testing purposes, which comprise a ceramic support containing 75% Al₂O₃, 11% SiO₂, 9% Fe₂O₃, and 3% TiO. However, it should be understood again that a wide variety of particles / microparticles, such as sand, silica-based granular particles, and / or calcium carbonate granular particles, can be used equivalently. The invention is not limited to specific heat transfer particles.

[0081] As previously stated, the heat transfer fluid 205 may include any heat transfer liquid, gas, solid, or mixture thereof suitable for a particular heat transfer application and conditions. In thermoelectric or process waste heat applications, steam, nitrogen, carbon dioxide, air, or other process gases may be used as the heat transfer fluid. In other applications, the heat transfer fluid 205 may include molten salt.

[0082] Use vertically aligned tubes (i.e., with) Figure 2 The vertical axis alignment of the tubes (XX aligned with the vertical axis) allows for variations in tube and shell lengths without the need for bends in the tubes, thus reducing the need for manifolds / bends and avoiding stagnation and void areas (as discussed previously) that occur when using horizontal tubes. This maximizes the use of the entire outer surface of each heat transfer tube for heat transfer. The number of tubes can also be optimized by using longer tubes in conjunction with higher quality flux designs, which will make the design of larger-scale systems more practical and feasible.

[0083] While not wishing to be confined to any particular theory, the inventors have discovered that when each heat transfer tube 222 is sufficiently long, typically greater than 1 m, the particle-side heat transfer coefficient through the tube wall from the heat transfer particle flow to the heat transfer fluid approaches a constant value, even as the velocity of the heat transfer particle flow increases. The inventors believe this is due to the rapid reduction in the length of the heat inlet region, which allows the heat transfer particle flow to become thermally fully developed. Without mixing, the particle-side heat transfer coefficient can only be improved by narrowing the radial width of the heat transfer particle flow relative to the wall (heat transfer surface) of the heat transfer tube 222, thereby ensuring effective heat transfer from all particles in the flow. This solution presents practical challenges because the thermal expansion of the heat transfer tube 222 can cause flow channeling / blockage in such a narrow particle flow.

[0084] The heat transfer particle flow is divided into multiple stages to prevent the flow from fully developing thermally. For example... Figure 2 As shown, multiple flow distribution plates 250 (serving as dividing elements) are included at intervals along the length of the vertical tube array 220. Each flow distribution plate 250 is designed to divide the particle heat exchanger 200 into a series of short particle beds. Figure 2S1, S2, S3, S4, and S5 in the diagram are used to redistribute gravity-driven moving particles. Each flow distribution plate 250 includes a series of flow contraction openings 260, which include annular gaps located in the flow distribution plate 250 at the intersection of the flow distribution plate 250 and each heat transfer tube 222. These flow contraction openings 260 include annular gaps extending annularly around each heat transfer tube 222. This gap creates flow contraction in the particle flow, causing particles to move toward and through the configuration. This creates a new heat inlet region at each configuration and forces the particles to remix at the end of each stage before entering the next stage, thereby improving the particle-side heat transfer coefficient. Each flow contraction opening 260 includes tube support fingers 265 ( Figure 2 (A) The tube-supporting fingers 265 extend from the flow distribution plate 250 across the flow contraction opening 260 to engage the surface of each heat transfer tube 222, thereby holding the tube array in place within the particle heat exchanger 200, which is a position aligned with the axis XX (i.e., vertically). The fingers 265 include tabs extending from the flow distribution plate 250 to engage the heat transfer tubes 222. However, it should be understood that rods, flanges, ribs, or similar protrusions extending from the flow distribution plate 250 or from the heat transfer tubes 222 can also be used. The fingers 265 are also configured to allow axial thermal expansion of the heat transfer tubes 222 upon heating and also maintain a consistent particle flow path between the heat transfer tubes 222.

[0085] Therefore, this invention provides an alternative method for narrowing the width of the particle flow by providing mixing of the heat-transferring particle flow at different points along the flow path. This invention addresses the inherent heat transfer barrier limitations associated with long and fast-moving bed particles, providing a design pathway toward more cost-effective commercial-scale PHX.

[0086] Figure 3 A second embodiment of the particle heat exchanger 200A according to the present invention is illustrated. Figure 3 A front cross-sectional view of the 200A particle heat exchanger is provided. Figure 3 (A) and top section ( Figure 3 (B)). The particle heat exchanger 200A has features designed for... Figure 2 The particle heat exchanger 200 shown has a substantially the same configuration as described above. Similar features are thus provided with respect to... Figure 2The same reference numerals are used for the particle heat exchanger 200 shown. In this embodiment, the flow distribution plate 250 includes a fluidizing gas device 267 configured to create a localized particle fluidization zone in the region of the flow contraction. Thus, the flow distribution plate 250 (separator) serves as a channel for supplying the fluidizing gas. The localized particle fluidization zone further enhances the particle-side heat transfer coefficient. The fluidizing gas device 267 typically includes a gas injection point, such as a nozzle located at the top of the flow distribution plate 250, which has a fluid connection to a fluidizing gas inlet 269 on one side of each flow distribution plate 250. This use of the fluidizing gas device 267 creates bubbling (or bubble) fluidization in the particle bed at the bottom of selected or all stages or grades in the particle heat exchanger 200A. Bubbling fluidization allows the particles to mix before entering the next stage to enhance particle-side heat transfer.

[0087] Figure 4 A third embodiment of the particle heat exchanger 200B according to the present invention is illustrated. Figure 4 A front cross-sectional view of particle heat exchanger 200B is provided. Figure 4 (A) and top section ( Figure 4 (B)). Particle heat exchanger 200B has features designed for Figure 2 The particle heat exchanger 200 shown has a substantially the same configuration as described above. Similar features are thus provided with respect to... Figure 2 The same reference numerals are used for the particle heat exchanger 200 shown. In this embodiment, the free space surrounding the shell of the heat transfer tube 222 has been replaced by a plurality of spaced-apart containers 270, each container 270 surrounding the heat transfer tube 222 therein. In the illustration, each spaced-apart container 270 is formed by a cylindrical shaft 271 or aperture coaxially surrounding each heat transfer tube 222. However, it should be understood that this can also be provided by a plurality of elongated tubes extending coaxially around each heat transfer tube 222.

[0088] As shown in the figure, each stage is formed by blocks 272 having multiple spaced-apart shafts 271. Heat transfer tubes 222 extend through each spaced-apart shaft 271. Each shaft 271 has a diameter larger than the outer diameter of the heat transfer tubes 222 extending through it, thus forming an annular gap between them. The entire heat exchanger comprises two or more stacked blocks 272, thereby allowing each flow distribution plate 250 to be located between adjacent stacked blocks 272.

[0089] Each block 272 preferably comprises a high-temperature ceramic block, with heat transfer tubes 222 concentrically located inside these shafts 271. Figure 4 This configuration forms an annular flow contraction opening 260, thereby allowing hot particles to flow through and transfer heat to the heat transfer fluid inside the heat transfer tube 222, while the aforementioned embodiment allows all the space between the heat transfer tubes 222 to be used as a particle flow channel.

[0090] Each flow distribution plate 250 includes flow contraction openings and tube support arms similar to those described above to enhance mixing at the end of each stage and ensure a consistent annular gap between the inner wall of shaft 271 and the outer wall of heat transfer tube 222. The annular flow contraction opening 260 between the plate orifice and the tube is designed to be smaller than the gap between the orifice and the tube of the ceramic block. This ensures that the particle-side heat transfer coefficient can be improved by utilizing continuous new heat inlet regions and remixing of particles 207.

[0091] The particle-side heat transfer coefficient can be improved in each of the above embodiments by using one or more of the following additional features:

[0092] • Narrower flow contraction opening 260 (annular gap);

[0093] • A spiral insert inside the annular gap in the shaft of block 272 (third embodiment only);

[0094] • Adding (welding) longitudinal fins to the tube increases particle travel residence time and heat transfer area, and also creates axial and rotating particle flow patterns to enhance mixing.

[0095] Figure 5 Examples Figure 2 and Figure 4 Variations of the particle heat exchangers 200 and 200B shown. Particle heat exchanger 200C has a design for... Figure 2 The particle heat exchanger 200 shown has a substantially the same configuration as described above. Similar features are thus provided with respect to... Figure 2 The same reference numerals are used in the accompanying drawings for the particle heat exchanger 200C. In this particle heat exchanger 200C, radial fins (protrusions) 280 are included on each heat transfer tube 222, longitudinally spaced from the flow contraction and prior to the flow distribution plate (separator) 250, along the length of the heat transfer tube 222 relative to the flow direction of the heat transfer particles 207. These radial fins 280 extend circumferentially around each heat transfer tube 222. It has been found that the radial fins 280 at this location enhance the mixing of the particles 207, which can result in complete renewal of the heat inlet region in subsequent stages.

[0096] like Figure 5 As best shown in (B), the radial fins 280 interrupt the thermal boundary layer of the particles (in Figure 5In (B), the particles (284, which are colder than the bulk particles) near the wall 285 of the heat transfer tube develop and then mix with the hot particles in the bulk flow of particles 207 before flowing through the annular gap 287 of the flow distribution plate 250. In this case, at the start of the subsequent stage below, the particles 288 near the wall 285 of the heat transfer tube can be completely replaced by hot particles, resulting in complete renewal of the heat inlet region (complete mixing of particles 207). This has been found to further improve the particle-side heat transfer coefficient of the particle heat exchanger 200C.

[0097] Example

[0098] The following examples are based on Figure 2 The modeling and initial experimental work of the particle heat exchanger 200 shown is presented. This work initially involves the modeling and analysis of heat transfer of the moving particle bed relative to the heat transfer wall (see Examples 1 and 2). Experimental verification was then performed using experimental test benches (Examples 3 and 4).

[0099] Example 1: Heat Transfer Analysis - 2D Heat Transfer Model

[0100] Figure 6 A heat transfer model for a single-bed tube-in-bed PHX is presented for solving the two-dimensional steady-state energy conservation equations. This model is established to understand particle-side heat transfer and to provide guidance for conceptual design. Given the axisymmetry condition relative to the tube's central axis, the tube-in-bed PHX can be assumed to be a 2D axisymmetric problem rather than a 3D problem. In this model, the particles are assumed to act as a single continuous medium moving downwards along the outer surface of the tube (heat transfer wall) under gravity. Heat transfer between the moving particle bed and the heat transfer wall occurs through radial thermal conduction. It can consist of two thermal resistances: particle-wall contact thermal resistance (…). R nw ), wherein heat transfer occurs between the first layer of particles (considering the higher porosity region of spherical particles in contact with the wall) and the heat transfer medium; and thermal resistance is controlled by effective heat conduction within the bulk flow. R b In this example, the inlet particle and constant wall temperature are set to 800°C and 750°C, respectively, while taking into account a particle diameter of 350 μm.

[0101] refer to Figure 6 The model is based on the following energy equation:

[0102]

[0103] Where: ρ is the bulk density of the particle. c p It is the specific heat capacity of the particles. u p It is the particle bed velocity.T p It is the particle temperature. k eff It is the effective thermal conductivity of the particles. r and y These are the radial and axial coordinates, respectively. The left side of the above equation represents the net enthalpy of the particle flow in the control volume, while the right side represents the effective heat conduction in the radial direction of the control volume.

[0104] Body-to-wall heat transfer coefficient ( h p ):

[0105]

[0106] in, h nw It is the heat transfer coefficient from the wall to the particles, and h b It is the heat transfer coefficient generated by the heat conduction of the main flow.

[0107] The Zehner-Schlunder model (Zehner and Schlunder, 1970) was used to calculate the effective thermal conductivity within the bulk flow. In this example, a solid fraction of 0.6 was used for a packed bed with spherical particles.

[0108] The wall-to-particle heat transfer coefficient is calculated using the method proposed by Botterill and Denloye (1978). In this example, the effect of radiative heat transfer is not considered.

[0109] The results of the modeling are Figures 7 to 10 The diagram illustrates different distances between the particles and the wall (heat transfer surface) of the heat transfer tube. d s ) and for different heat transfer tube lengths ( L hx That is, the length of the heat transfer tube is 0.2 m. Figure 7 ), 0.5 m ( Figure 8 ), 1.0 m ( Figure 9 ) and 2.0 m ( Figure 10 ), heat transfer coefficient from body to wall ( h p How does the particle bed speed ( u p It changes with the changes in ). Comparison Figures 7 to 10 It can be seen that in shorter heat transfer tube lengths of 0.5 m or less ( L hx Under these conditions, the particle bed velocity ( u p The change in the bulk-to-wall heat transfer coefficient increased ( hp However, for heat transfer tube lengths of 1.0 m or greater, the particle bed velocity ( u p ) on changing the heat transfer coefficient from the bulk to the wall ( h p The effect of ) is much lower. As mentioned earlier, even when the velocity of the heat transfer particle flow increases, the particle-side heat transfer coefficient through the heat transfer tube wall from the heat transfer particle flow to the heat transfer fluid will remain close to a constant value.

[0110] In summary, the results show that for pipe lengths greater than 1 m ( L hx ), increase particle bed velocity ( u p This will not increase the body-to-wall heat transfer coefficient. h p ), because the particle flow becomes thermally developed. Furthermore, reducing the distance ( d s ) will increase h p This is because there are fewer particles in the channel (resistance is lower). However, from a practical point of view, maintaining a consistent gap as narrow as 2 mm can be challenging.

[0111] Example 2: Heat Transfer Analysis - Staged Moving Bed 2D Heat Transfer Model

[0112] Figure 11 A schematic diagram of a multi-stage moving bed particle heat exchanger connected in series is shown. In this example, PHX is divided into multiple stages ( N stage Furthermore, it is assumed that the particles are fully mixed at the outlet before proceeding to the next stage. In each stage, the heat transfer between the moving particle bed and the heat transfer wall is calculated by solving the two-dimensional steady-state energy equation using the method mentioned in Example 1.

[0113] Figure 12 The table shows the particle bed velocity for single-stage PHX, 4-stage PHX, and 10-stage PHX. u p The body-to-wall heat transfer coefficient (a function of) h p Comparison of total heat exchanger tube lengths in all three cases. L hx The value was set to 2 m. Results showed that as the particle bed velocity ( u p The increase in particle-side heat transfer coefficient, compared to a single-stage PHX, is due to the fact that a series of shorter PHXs can improve the particle-side heat transfer coefficient by remixing the particles at the outlet before entering the next segment or stage and also allows for the continuous generation of new heat inlet regions.

[0114] Example 3 - Experimental Work - Cold Flow Test Stand (Implementation Method 1)

[0115] Conduct experimental work to study the basis Figure 2 The particle flow behavior in the heat exchanger configuration shown. For example... Figure 13A , Figure 13B As shown, the test bench is constructed to study particle motion through a heat exchanger under room temperature conditions (i.e., without the use of heated particles). To visualize the flow, the test bench's housing and partitions are made of transparent polycarbonate, which is configured to surround the particle flow and the metal tube bundle.

[0116] The experimental setup utilizes particles (300 μm ceramic proppant containing 75% Al2O3, 11% SiO2, 9% Fe2O3, and 3% TiO) encapsulated in the shell and upper chamber for testing. The particles are released from the heat exchanger by opening a sliding door at the bottom of the test setup.

[0117] The result of one run Figure 13B Examples from (A) to (D) are provided. Figure 13B (A) through (D) show the top of the particle flow through the cold flow test bench from the full ( Figure 13B (A)) to 2 / 3 of the flow completed ( Figure 13B Progress was made in (D). Experimental results showed that there was no particle blockage or significant particle retention zone when the flow passed through the annular gap of the flow distribution plate. In addition, experimental results showed that the presence of the flow contraction zone using the partition plate did indeed cause the particle flow to remix at each flow stage as it flowed toward and through each flow contraction. Each stage did indeed act as a short particle bed, which was supplied to the subsequent stages below by gravity.

[0118] Example 4 - Thermal Particle Test Stand

[0119] according to Figure 2 The heat exchanger configuration shown is used to construct a hot particle test bench. For example... Figure 14 As shown, the apparatus includes a hot chamber incorporating electric heating elements, a single-shell tubular particle heat exchanger, a particle flow control valve, and a cold chamber (container). Dense particles are first heated to the desired temperature in the hot chamber, and the hot particles are released to the shell side of the heat exchanger by opening the particle flow control valve. Heat is extracted from the hot particles into cooling water in the tubes, and then the particles are released into the container. Temperature and mass flow rate will be measured throughout the experiment.

[0120] The experimental setup used particles (350 μm ceramic proppant containing 75% Al2O3, 11% SiO2, 9% Fe2O3 and 3% TiO) for testing.

[0121] Based on the mass flow rates and temperatures measured on both the particle and water sides of the particle heat exchanger, the bulk-to-wall heat transfer coefficient is calculated using the following equation ( h p )value:

[0122]

[0123] Among them, the overall heat transfer coefficient ( U hx The logarithmic mean temperature difference method for counter-current heat exchangers is used for calculation, and the water-side convective heat transfer coefficient ( h f The Gnielinski equation is used for calculation.

[0124] The hot particle test bench will be used to study the heat transfer coefficient from the particle bulk to the wall. h p The experimental results will be used to validate the models developed in Examples 1 and 2 and to confirm the enhanced particle-side heat transfer in the staged particle heat exchanger design.

[0125] Figure 15 The measured and simulated bulk-to-wall heat transfer coefficients of the particles are shown for single-stage PHX and 10-stage PHX. h p The value is related to the particle bed velocity ( u p Comparison within the range of ). Total heat exchanger tube length in both cases ( L hx The value is 1 m. It can be seen that the heat transfer models developed in Examples 1 and 2 yielded... h p The values ​​are in excellent agreement with the measurements from both PHX models. In the case of a 10-stage PHX, the heat transfer model assumes partial mixing of particles near the contraction gaps in each stage. Experimental results also confirm that, compared to heat exchanger designs without multiple stages, [the following is likely a separate point and should be treated separately:] , Figure 2 The heat exchanger 200 shown is designed for enhanced particle-side heat transfer. This is based on a heat transfer model assuming complete mixing of particles near the contraction gap at each stage. Figure 15 The results shown indicate that particle-side heat transfer can be further enhanced due to the complete renewal of the heat inlet effect at each stage (i.e., complete mixing of particles).

[0126] Those skilled in the art will understand that, apart from those specifically described, the invention described herein is susceptible to variations and modifications. It should be understood that the invention includes all such variations and modifications falling within the spirit and scope of the invention.

[0127] When the terms “comprise,” “comprises,” “comprised,” or “comprising” are used in this specification (including the claims), they should be interpreted as specifying the presence of the stated feature, integer, step, or component, but do not exclude the presence of one or more other features, integers, steps, components, or combinations thereof.

Claims

1. A particle heat exchanger, the particle heat exchanger comprising: Housing, the housing comprising: An entrance, located at the top of the housing; and The exit is located below the inlet. The housing is configured to surround a heat transfer particle flow that flows downward from the inlet to the outlet within the housing; At least two heat transfer tubes, laterally spaced apart within the housing, each heat transfer tube comprising a heat transfer medium, each heat transfer tube being enclosed within the housing and in contact with the heat transfer particle flow within the housing, each heat transfer tube extending parallel to an axis extending between the inlet and outlet of the housing; and At least one partition is located between the inlet and the outlet of the housing, the at least two heat transfer tubes extend through each partition, each partition includes at least one opening located near and around the intersection of the heat transfer tubes and the partition, the at least one opening being configured to form at least one flow contraction in the heat transfer particle flow between the inlet and the outlet of the housing.

2. The particle heat exchanger according to claim 1, wherein, The housing is configured to guide the heat transfer particle flow vertically downward from the inlet to the outlet.

3. The particle heat exchanger according to claim 1, wherein, The axis between the inlet and the outlet defines a vertical axis, and each of the heat transfer tubes is vertically oriented within the housing.

4. The particle heat exchanger according to claim 1, wherein, The at least one opening in the separator causes the heat transfer particle flow to contract by at least 20% of the cross-sectional flow area within the housing.

5. The particle heat exchanger according to claim 1, wherein, The opening includes a hole located near and around the intersection of each of the heat transfer tubes and each separator.

6. The particle heat exchanger according to claim 1, wherein, The opening includes an annular opening surrounding the intersection between each of the heat transfer tubes and each separator.

7. The particle heat exchanger according to claim 1, wherein, Each opening includes at least one arm extending from the separator to the heat transfer tube, the at least one arm being configured to position the heat transfer tube within each opening.

8. The particle heat exchanger according to claim 1, wherein, The heat transfer medium includes a heat transfer fluid flowing through each heat transfer tube.

9. The particle heat exchanger according to claim 8, wherein, The flow of the heat transfer fluid is in at least one of the counter-current or parallel-current direction relative to the heat transfer particle flow.

10. The particle heat exchanger according to claim 1, wherein the particle heat exchanger comprises three or more heat transfer tubes spaced laterally within the housing.

11. The particle heat exchanger according to claim 1, wherein, The heat transfer tubes are arranged in a vertical tube array within the housing.

12. The particle heat exchanger according to claim 1, wherein, Each heat transfer tube consists of a linear cylindrical tube.

13. The particle heat exchanger according to claim 1, wherein, Each heat transfer tube is made of a thermally conductive material selected from metals, ceramics, and carbides.

14. The particle heat exchanger according to claim 1, wherein, The particle heat exchanger includes at least two spacers spaced apart between the inlet and the outlet of the housing along the length of each heat transfer tube.

15. The particle heat exchanger according to claim 1, wherein, The at least one separator includes a planar element that is radially oriented relative to the axis extending between the inlet and the outlet, so as to divide the housing into at least two separate solid particle flow chambers.

16. The particle heat exchanger according to claim 1, wherein, Each separator consists of a sheet or plate.

17. The particle heat exchanger according to claim 1, wherein, The housing includes a container with an internal space that surrounds all the heat transfer tubes within the internal space.

18. The particle heat exchanger according to claim 1, wherein, The housing includes a plurality of spaced-apart solid flow conduits, each having an inlet and an outlet, and each containing a heat transfer tube extending therefrom.

19. The particle heat exchanger according to claim 18, wherein, The housing comprises a plurality of spaced-apart containers, each of which encloses a heat transfer tube therein.

20. The particle heat exchanger according to claim 18, wherein, The housing includes a mounting body with a plurality of spaced-apart shafts, through which heat transfer tubes extend, each shaft having a diameter larger than the outer diameter of the heat transfer tubes extending therethrough.

21. The particle heat exchanger according to claim 20, wherein, The housing includes at least two stacked mounting bodies, with each spacer located between adjacent stacked mounting bodies.

22. The particle heat exchanger according to claim 1, further comprising at least one fluidizing gas device located at or near the at least one flow contraction.

23. The particle heat exchanger according to claim 22, wherein, The fluidizing gas device is configured to generate localized fluidizing particle bubbles near the at least one flow contraction.

24. The particle heat exchanger of claim 1, further comprising at least one helical insert extending around at least one heat transfer tube.

25. The particle heat exchanger of claim 1, further comprising at least one radial element extending radially from the surface of at least one heat transfer tube into the housing.

26. The particle heat exchanger according to claim 25, wherein, The radial element is longitudinally spaced from the separator at a position preceding the separator along the length of the heat transfer tube relative to the direction of the heat transfer particle flow.

27. The particle heat exchanger according to claim 1, wherein, The heat transfer particles include solid particles.

28. The particle heat exchanger according to claim 1, wherein, The heat transfer particles have an average particle size between 100 μm and 800 μm.

29. The particle heat exchanger according to claim 1, wherein, The heat transfer particles include ceramics.

30. The particle heat exchanger according to claim 1, wherein, Each heat transfer tube is made of a thermally conductive material selected from stainless steel, nickel-based alloys, alumina, silicon carbide, and graphite.

31. The particle heat exchanger according to claim 25, wherein, The radial element is a rib or a fin.

32. The particle heat exchanger according to claim 29, wherein, The ceramic is an alumina-based ceramic.

33. The particle heat exchanger according to any one of claims 1 to 32, wherein the particle heat exchanger comprises a heat exchanger in thermal communication with a solar receiver of a solar / thermal system.

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