US20080277092A1

US20080277092A1 - Water cooling system and heat transfer system

Info

Publication number: US20080277092A1
Application number: US12/151,767
Authority: US
Inventors: Frederick P. Layman; Maximilian A. Biberger
Original assignee: SDC Materials Inc
Current assignee: SDC Materials Inc
Priority date: 2005-04-19
Filing date: 2008-05-08
Publication date: 2008-11-13
Also published as: US20120285548A1; WO2008140745A1; EP2153157A4; JP2014240077A; JP5792776B2; EP2152442A1; US7905942B1; US8945219B1; JP2014061518A; US8051724B1; WO2008140786A1; US8007718B1; US20130316896A1; US8142619B2; WO2008140823A1; US20150367331A1; JP5275342B2; JP2016027943A; US9180423B2; JP2014000571A

Abstract

A heat exchanger comprising: a gas transport conduit providing a channel through which a fluid mixture can flow; an outer conduit disposed around the gas transport conduit, the outer conduit having a first cap covering a first end and a second cap covering a second end, the gas transport conduit passing through the outer conduit; and a conductive tube passing through the outer conduit, providing a channel through which a circulating fluid can flow through the outer conduit, wherein a static fluid chamber is formed between the conductive tube and the gas transport conduit, the static fluid chamber configured to house a static fluid, wherein the gas transport conduit is configured to conduct heat from the fluid mixture in the gas transport conduit to the static fluid and the conductive tube is configured to conduct heat from the static fluid to the circulating fluid.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to co-pending U.S. patent application Ser. No. 11/110,341, filed on Apr. 19, 2005, entitled, “HIGH THROUGHPUT DISCOVERY OF MATERIALS THROUGH VAPOR PHASE SYNTHESIS” and to co-pending U.S. Provisional Application Ser. No. 60/928,946, filed May 11, 2007, entitled “MATERIAL PRODUCTION SYSTEM AND METHOD,” both of which are hereby incorporated by reference as if set forth herein.

FIELD OF THE INVENTION

The present invention relates generally to methods of and systems for cooling gas transport conduits configured to conduct hot gasses or gaseous mixtures.

BACKGROUND OF THE INVENTION

In a gas phase particle production reactor, basic product species are formed within extremely short time spans following ejection of hot, reactive matter from an energy delivery zone. Although particle species are formed rapidly, cooling of the gas-particle product must be carefully controlled to achieve desired particle characteristics without contamination. In many cases, this carefully controlled cooling occurs within a gas transport system configured to deliver the gas-particle product to collection points within the system.
Since hot gas-particle product contains and emits a large quantity of heat, gas transport systems adapted to conduct gas-particle product from gas phase particle production reactors must be designed to efficiently absorb and dissipate high heat loads. Because heat transfer between two systems occurs in proportion to the temperature differential between the two systems, efficient absorption of heat from the gas-particle product depends on maintaining the gas transport system at a significantly lower temperature than the gas-particle product, while efficient dissipation of heat from the gas transport system depends on maintaining an environment of still lower temperature in contact with the gas transport system. The independent requirements of absorption and dissipation are at odds. Gas transport systems are typically incapable of absorbing large quantities of heat without increasing their temperature. In most cases, the two requirements are balanced by actively cooling the gas transport system, which provides a controlled, low temperature environment into which the gas transport system can dissipate heat.
Within the prior art, the most common active cooling strategies for gas transport systems involve forced fluid cooling. A variety of forced fluid cooling systems, including forced-gas cooling systems and liquid cooling systems, are employed in prior art gas transport coolers.
Forced-gas cooling systems typically include one or more fans, configured to force gas through one or more heat exchange structures thermally coupled with the gas transport system. Heat moves from the gas-particle product into the gas transport system and then into the heat exchange structures. Typically, the heat exchange structures include heat rejecters or heat sinks configured to present a large surface area interface to the gas within a heat exchange region. As gas moves through the heat exchange region and across the large surface area of the heat rejecter or heat sink, it convectively cools the heat rejecter or heat sink. Although such systems are simple and relatively inexpensive to operate, they are less efficient than liquid cooling systems because the heat capacity of gas is generally less than that of liquid, gas cools through mostly convective means and gas cannot be cooled as readily as can liquid. Thus, forced-gas cooling systems are ill suited to cool high heat load gas-particle mixtures.
Liquid cooling systems typically include liquid circulation system configured to deliver fluid through one or more heat exchange structures thermally coupled with the gas transport system. As in forced-gas systems, the heat exchange structures are typically configured to present a large surface area for interaction with the liquid within a heat exchange region. Heat is absorbed into the gas-transport system and conducted into the heat exchange structures. As liquid moves across the heat exchange surface, heat dissipates from the heat exchange structures through conductive and convective means into the liquid and heated liquid flows away from the heat exchange region. Typically, heat is removed from the heated liquid via some further cooling or refrigeration mechanism.
For efficient cooling, the entire volume of the heat exchange region must be constantly supplied with fresh, cool liquid. Systems having high volume heat exchange regions require higher volumes of cool liquid to operate efficiently, resulting in high operating costs. While low volume heat exchange regions are known, fabrication methods are difficult, expensive and result in high set-up costs. Further, many low volume systems are very sensitive to contamination, and thus require sometimes expensive precautions, such as filters, and regular maintenance to run smoothly.
Current methods for cooling gas transport systems rely either on forced-gas cooling, which lacks sufficient efficiency to handle high heat load systems, or liquid cooling systems, which are expensive to build and maintain.

SUMMARY OF THE INVENTION

According to the present invention, a cooling system for a conduit is presented. In an exemplary aspect, a cooling system according to the present invention is used to cool a conduit that transports gas mixtures. The cooling system is primarily intended to dissipate heat absorbed by the conduit from the gas particle product it transports. In an exemplary system, hot gas-particle product is emitted from gas phase particle production reactors, such as flame reactors, plasma reactors, hot wall reactors and laser reactors. The conduit conducts and conditions the gas-vapor mixtures ejected from the reactor, absorbing heat from the mixtures through multiple means. The cooling system functions to dissipate heat absorbed within the conduit and prevent overheating of the conduit.
The present invention describes a cooling system for cooling selected portions of a gas transport conduit within a conduit system. Preferably, the cooling system comprises at least one cooling element configured to cool a portion of the gas transport conduit, comprising a section of outer conduit having a first end and a second end. The cooling element is preferably fitted around the portion of the gas transport conduit to form a toroidal channel between the inner surface of the outer conduit and the outer surface of the gas transport conduit. The toroidal channel formed between the outer conduit and the gas transport conduit has a first opening at the first end of the conduit and a second opening at the second end of the conduit. A highly heat conductive tube structure is placed within the outer conduit to form the toroidal channel. Furthermore, the highly heat conductive tube structure preferably does not seal the channel to fluid flow at any point therein, so that fluid may move freely within the toroidal channel with the highly heat conductive tube structure in place. However, in an alternative embodiment, the cooling system incorporates partitions within the toroidal channel, which seal the toroidal channel to fluid flow except through the highly heat conductive tube structure. In this aspect, the toroidal channel is divided into several chambers, each of which can have a different fluid therein, with the highly conductive tube structure passing through each of the several chambers.
With the highly heat conductive tube structure installed in the toroidal channel, a first cap coupled with the first opening and a second cap coupled with the second opening of the toroidal channel provide a seal between the gas transport conduit and the conduit. The toroidal channel is filled with a static fluid, preferably a liquid, surrounding and thermally contacting the highly heat conductive tube structure. At least one of the caps is configured with a port to allow fluid delivery therethrough into the highly heat conductive tube structure. A fluid reservoir system is coupled with the one or more ports and thereby with the highly heat conductive tube structure. Although in the preferred embodiment the caps and the outer conduit are modularly formed and sealed to one another, the caps and the outer conduit can be integrally formed in alternative embodiments.
Thus, each embodiment of the present invention includes two fluid systems, separated from one another: a circulating system (referred to as “fluid” or “circulating fluid”) and a static system (referred to as “static fluid). The fluids chosen for use within each system have preferred characteristics, which differ depending on the specifics of each embodiment.
As the conduit system conducts hot gas, it absorbs heat from the gas. Because the gas cools as it travels through the conduit system, some portions of the conduit system absorb more heat than others. An exemplary portion of a gas transport conduit within the conduit system is equipped with a cooling system as described in the preceding paragraph.
The cooling system of the present invention operates by removing heat from the gas transport conduit via fluid flow. As heat is absorbed into the gas transport conduit from the gas within the conduit, the cooling system works to remove heat from the conduit through the external surfaces of the conduit. Heat moves from the conduit system into the static fluid, heating the static fluid. The static fluid, being in thermal contact with the highly heat conductive tube structure, conducts heat into the highly heat conductive tube structure. Fluid flows from the fluid reservoir system into the highly heat conductive tube structure, absorbing heat from the conduit system through the highly heat conductive tube structure and the static fluid. The fluid flows from the highly heat conductive tube structure back into the fluid reservoir system, or into a different fluid reservoir. As one skilled in the art will recognize, in a closed loop system (where the fluid returns to the same reservoir system), in order to maintain cooling efficiency, the fluid is preferably cooled via external means, such as refrigeration, before being resupplied to the highly heat conductive tube structure
Functionally, each cooling cell within cooling system includes several components: a heat exchange region, and a fluid flow control and supply system. Functioning together, these components allow a cell to provide effective cooling to a specific region of a conduit system. A cooling system having a plurality of such cells working in concert provides selective, extensible and configurable cooling to a conduit system. The present invention includes a desired structure and function for each component of a cell within the system.
There are several heat exchange regions in the present invention. In an assembled system, the highly heat conductive tube structure sits within the toroidal channel defined between the gas transport conduit and the outer conduit and filled with the static fluid. Preferably, the highly heat conductive structure is wound in a spiral in the toroidal chamber along the conduit. The region of interface between the conduit and the static fluid within the toroidal channel forms a first heat exchange region: heat flows from the gas transport conduit into the static fluid. The surface of the interface between the static fluid and the highly heat conductive tube structure within the toroidal channel forms a second heat exchange region: heat is conducted from the static fluid into the highly heat conductive tube structure. The inner surface of the highly heat conductive tube structure forms a third heat exchange region: heat flows from the highly heat conductive tube structure into the circulating fluid.
The highly heat conductive tube structure is preferably formed from bent highly heat conductive material. Preferred materials include metals, such as copper, and highly heat conductive thermoplastics. As mentioned above, the highly heat conductive tube structure permits fluid flow there-through. The present invention contemplates a variety of structures to permit fluid flow. In various embodiments, the highly heat conductive tube structure comprises porous structures and/or channel structures defining fluid flow paths. Preferably, the structures present a high surface area for heat exchange, relative to the volume of the highly heat conductive tube structure.
Preferably, the highly heat conductive tube structure is spirally wound to form a toroidal shape encircling the gas transport conduit within the toroidal channel, much like the shape of a coiled spring. The present invention contemplates a variety of configurations of the highly heat conductive tube structure within the toroidal channel, including coiled, folded and layered configurations. The highly heat conductive tube structure can be formed independently from the conduit, or formed around the conduit. Regardless of the method of formation, the highly heat conductive tube structure is configured to fit within the toroidal channel.
In an exemplary embodiment, copper tubing coiled around the gas transport conduit forms the highly heat conductive tube structure. The copper tubing is preferably coiled coarsely, and may but need not physically contact the gas transport conduit. Placement of the outer conduit to surround the highly heat conductive tube structure forms a toroidal channel containing the highly heat conductive tube structure. The toroidal channel is sealed and filled with a static fluid. The filling may be accomplished following the sealing of one end of the outer conduit and prior to the sealing of the other end. Alternatively, the filling may be accomplished through a valve system positioned in either or both ends of the heat exchanger.
The fluid flow control system has several functions. The rate of heat dissipation within a fluid cooling system depends on many factors, several of which relate to the rate and type of fluid flow within the system. An effective fluid flow control system includes means to channel the fluid to the desired portions of the heat exchange region. Also, because fluids expand under heating, and because heat dissipation within a fluid cooling system depends on heating of the fluid, the fluid control system must account for pressure changes within the fluid. Similarly, the toroidal chamber formed within the outer conduit and the two seals preferably includes a valve system configured to account for pressure changes within the fluid.
The present invention presents a fluid control system comprising several parts. The outer conduit provides a confining structure, which forms the toroidal chamber in which static fluid is positioned. Thus, the conduit determines the total fluid volume within the toroidal chamber, exclusive of the fluid path within the highly heat conductive tube structure. Furthermore, each of the caps sealing the ends of the outer conduit are preferably equipped with a plurality of ports. These ports determine the pattern in which fluid flows into the highly heat conductive tube structure and thus help determine, in concert with the flow structures within the highly heat conductive tube structure, the flow patterns through the highly heat conductive tube structure. Additionally, the cap structures preferably include one or more pressure relief valves, configured to release fluid from the system should a sudden rise in pressure occur. Furthermore, the fluid control system can include a pump configured to deliver fluid through the plurality of ports on one of the sealing caps.
The outer conduit is preferably configured along with the highly heat conductive tube structure to define a predetermined fluid volume within the toroidal region. The specific volume and flow rate of an embodiment depend on the heat loads for which that embodiment is designed. Roughly, higher volumes and flow rates will be required to handle higher heat loads. Conductivity and surface area are also considerations in determining required fluid volume.
Preferably, the outer conduit is formed from a durable, heat resistant material. The material forming the outer conduit need not be thermally conductive. In fact, in order to minimize heat dissipation through the outer conduit, at least the outer surface preferably comprises an insulating material. This configuration separates the heat dissipation and structural functions of the cooling system. Alternatively, the outer surface can be heat conductive to promote additional heat loss through radiation.
The caps couple with and seal the ends of the outer conduit. In the various embodiments the caps can be bonded, threaded, and/or bolted on to the outer conduit. The present invention contemplates any coupling that creates a seal between the cap and the outer conduit. Preferably, the caps comprise material similar to that in the outer conduit. Additionally, the seal between the conduit system and the caps can be formed in a variety of ways: the caps can be bonded, pressure fitted, or held in place by o-ring type seals. The preferred method of sealing the caps provides for expansion and contraction of the caps as the heat exchanger is heated and cooled.
Furthermore, the caps each preferably include a plurality of ports. As mentioned, one of the ports provides a pressure relief system for the fluid system, preferably at each end of the outer conduit. The other ports provide fluid delivery into the highly heat conductive tube structure in a specified configuration. The configuration of the ports and the configuration of the fluid channels within the highly heat conductive tube structure complement one another to form desired flow paths through the system. The configuration of the paths and the rate of fluid delivery thereto partially determine the rate of heat dissipation from the gas transport conduit to the fluid.
The fluid control system can further include a fluid pump and fluid supply system, which can reasonably be integrated into a single device, but can also be provided modularly. The fluid pump determines the rate of fluid delivery to the plurality of ports and thus the rate of fluid flow through the highly heat conductive tube structure. Higher fluid flow rates allow the system to dissipate greater amounts of heat. Accordingly the fluid flow rates are preferably varied as heat dissipation requirements vary.
Preferably, since the heat production within a gas production system incorporating a cooling system of the present invention is not necessarily static, the cooling system of the present invention can vary its fluid flow rates to accommodate varying requirements for heat dissipation. In one aspect of the present invention, a control system controls the pump and fluid supply system according to the observed temperature difference between fluid flowing into the heat exchange region and fluid flowing from the heat exchange region. If the temperature difference is beyond desired limits, the rate of flow is increased, so long as the maximum flow rate has not been exceeded.
The fluid supply system preferably provides cool fluid to the fluid pump. This fluid can be fresh, i.e., fluid which has not been used in the system before, or this fluid can be recirculated. If recirculated fluid is used, the fluid supply system preferably cools the recirculated fluid before resupplying it to the pump. The fluid supply system can incorporate a pressure relief valve. Several types of fluids are contemplated by the present invention. Preferred fluids have high thermal conductivity.
Within the several embodiments of the present invention, the preferred characteristics of the fluid and the static fluid can vary. Specifically preferred characteristics can differ both between the fluid and the static fluid within a given embodiment and within a given fluid between multiple embodiments. Important characteristics of the fluid include density, heat capacity, viscosity, and conductivity. In one aspect of the present invention, a static fluid and a circulating fluid both having a low thermal mass are chosen to allow rapid changes in the temperature of the heat exchanger. In other aspects of the present invention, circulating fluid and static fluid having high heat capacities are chosen to allow removal of large quantities of heat.
As a gas phase particle production system operates, hot gas product emitted from a reactor flows through a gas transport conduit within a conduit system. As the gas flows through the conduit it cools, dissipating heat into the gas transport conduit. Because heat dissipation is proportional to temperature differential, presuming a uniform rate of conduit heating, less heat is dissipated into the gas transport conduit as the gas becomes cooler, i.e., portions of the conduit further from the point at which hot gas is introduced into the conduit absorb less heat from the gas. Because of these differences, a cooling system according to the present invention preferably incorporates a variety of subsystems. The operation of one such subsystem is discussed below.
As hot gas flows through a gas transport conduit, heat dissipates into the conduit. Within the present invention, a highly heat conductive tube structure is coupled with the conduit and placed within a toroidal structure formed between the gas transport conduit and an outer conduit. The gas transport conduit and the highly heat conductive tube structure are in thermal contact through a static fluid within the toroidal chamber, which allows heat to dissipate from the gas transport conduit into the highly heat conductive tube structure. As heat flows from the gas transport conduit into the static fluid, fluid flows through the highly heat conductive tube structure, which is in contact with the static fluid. As fluid flows, heat is dissipated from the highly heat conductive tube structure into the fluid, thereby heating the fluid. Thus, heat dissipated from the gas transport conduit is physically removed via dissipation into a flowing fluid.
In one aspect of the present invention, a heat exchanger is provided. The heat exchanger comprises a gas transport conduit that provides a channel through which a fluid mixture can flow. An outer conduit is disposed around the gas transport conduit. The outer conduit has a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end. The gas transport conduit passes through the first cap, into the outer conduit, and through the second cap. A conductive tube passes through the outer conduit, thereby providing a channel through which a circulating fluid can flow into and out of the outer conduit. A static fluid chamber is formed between the conductive tube and the gas transport conduit. The static fluid chamber is configured to house a static fluid. The gas transport conduit is configured to conduct heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber and the conductive tube is configured to conduct heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.
In another aspect of the present invention, a cooling system is provided. The cooling system comprises a fluid supply system having an inlet and an outlet. The fluid supply system is configured to receive a heated circulating fluid through the inlet, cool the heated circulating fluid, and supply the cooled circulating fluid through the outlet. The cooling system also comprises a gas transport conduit that provides a channel through which a fluid mixture can flow and an outer conduit disposed around the gas transport conduit. The outer conduit has a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end. The gas transport conduit passes through the first cap, into the outer conduit, and through the second cap. A conductive tube has a tube inlet fluidly coupled to the outlet of the fluid supply system and a tube outlet fluidly coupled to the inlet of the fluid supply system. The conductive tube passes through the outer conduit, thereby providing a channel through which the circulating fluid can flow from the fluid supply system into the outer conduit via the tube inlet and out of the outer conduit to the fluid supply system via the tube outlet. A static fluid chamber is formed between the conductive tube and the gas transport conduit. The static fluid chamber is configured to house a static fluid. The gas transport conduit is configured to conduct heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber and the conductive tube is configured to conduct heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.
In yet another aspect of the present invention, a method of cooling a fluid mixture is provided. The method comprises providing an outer conduit and a conductive tube. The outer conduit is disposed around a gas transport conduit and has a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end. The gas transport conduit passes through the first cap into the outer conduit and through the second cap. The conductive tube passes through the outer conduit. A static fluid chamber is formed between the conductive tube and the gas transport conduit. The static fluid chamber houses a static fluid. The fluid mixture flows through the gas transport conduit into and out of the outer conduit. A circulating fluid flows through the conductive tube into and out of the outer conduit. The gas transport conduit conducts heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber. The conductive tube conducts heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a systematic view of one embodiment of a cooling system integrated into a particle processing system in accordance with the principles of the present invention.

FIG. 2 is a perspective view of one embodiment of a cooling system in accordance with the principles of the present invention.

FIG. 3 is a cross-sectional view of one embodiment of a heat exchanger in accordance with the principles of the present invention.

FIG. 4 is a partial cross-sectional view of one embodiment of a heat exchanger in accordance with the principles of the present invention.

FIG. 5 is a flowchart illustrating one embodiment of a method of cooling a fluid mixture in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The description below concerns several embodiments of the invention. The discussion references the illustrated preferred embodiment. However, the scope of the present invention is not limited to either the illustrated embodiment, nor is it limited to those discussed. To the contrary, the scope should be interpreted as broadly as possible based on the language of the Claims section of this document.
In the following description, numerous details and alternatives are set forth for purpose of explanation. However, one of ordinary skill in the art will realize that the invention can be practiced without the use of these specific details. In other instances, well-known structures and devices are shown in block diagram form in order not to obscure the description of the invention with unnecessary detail.
This disclosure refers to both particles and powders. These two terms are equivalent, except for the caveat that a singular “powder” refers to a collection of particles. The present invention may apply to a wide variety of powders and particles. Powders that fall within the scope of the present invention may include, but are not limited to, any of the following: (a) nano-structured powders (nano-powders), having an average grain size less than 250 nanometers and an aspect ratio between one and one million; (b) submicron powders, having an average grain size less than 1 micron and an aspect ratio between one and one million; (c) ultra-fine powders, having an average grain size less than 100 microns and an aspect ratio between one and one million; and (d) fine powders, having an average grain size less than 500 microns and an aspect ratio between one and one million.
Referring now to FIG. 1, a particle processing system 100 is provided. The particle processing system 100 includes the gas-particle mixture production system 110 coupled with the sampling zone 150 and the vacuum system 160 through the conduit system 120.
The gas-particle mixture production system 110 preferably produces particles entrained within a gas stream and provides the output fluid mixture to the conduit system 120. It is contemplated that the fluid mixture can be produced in a variety of ways. Some embodiments of the present invention revolve around the use of a nano-powder production reactor. In general, vapor phase nano-powder production means are preferred. The embodiments of the present invention can use elements of nano-powder production systems similar to those disclosed in U.S. patent application Ser. No. 11/110,341, filed on Apr. 19, 2005 and entitled, “HIGH THROUGHPUT DISCOVERY OF MATERIALS THROUGH VAPOR PHASE SYNTHESIS”, which is currently published as U.S. Publication No. 2005-0233380-A. In such a nano-powder production system, working gas is supplied from a gas source to a plasma reactor. Within the plasma reactor, energy is delivered to the working gas, thereby creating a plasma. A variety of different means can be employed to deliver this energy, including, but not limited to, DC coupling, capacitive coupling, inductive coupling, and resonant coupling. One or more material dispensing devices introduce at least one material, preferably in powder form, into the plasma reactor. The combination within the plasma reactor of the plasma and the material(s) introduced by the material dispensing device(s) forms a highly reactive and energetic mixture, wherein the powder can be vaporized. This mixture of vaporized powder moves through the plasma reactor in the flow direction of the working gas.
Referring back to FIG. 1, the fluid mixture, preferably a gas-particle stream, flows through the conduit system 120, where it is conditioned and conducted to the sampling zone 150. Within the sampling zone 150 portions of the gas-particle stream are separated and the particles therein isolated for further analysis. It is contemplated that condensed particles can be separated from the gas-particle stream in a variety of ways, including, but not limited to, the use of one or more filters. The bulk of the gas-particle stream flows through the sampling zone and into the vacuum system 160. The vacuum system 160 functions to draw the gas-particle stream from the production system 110 through the conduit system 120, forcing it through the sampling zone 150.
The conduit system 120 includes the conduit 140 configured to conduct and condition the gas-particle stream from the production system 110 to the vacuum system 160. The conditioning performed in the illustrated embodiment consists primarily of the cooling and the maintenance of entrainment of the particles. The gas-particle stream is cooled and its particle entrainment maintained by introduction of conditioning fluid through the port 142. Furthermore, the gas-particle stream transfers heat to the body of the conduit 140, which the cooling systems 170 and 180 dissipate. The conditioning fluid reservoir 130 provides conditioning fluid to the port 142 through the supply line 135. The vacuum system 160 provides a suction force within the conduit 140, drawing conditioning fluid into the port 142 to cool the gas-particle stream and maintain entrainment of particles therein.
The cooling systems 170 and 180 include the heat exchangers 172 and 182 respectively, which are coupled via the fluid lines 176 and 186 to the fluid supply systems 174 and 184. As the gas-particle stream dissipates heat into the conduit 140, that heat is conducted into the heat exchangers 172 and 182. The fluid supply systems 174 and 184 pump fluid through the heat exchangers 172 and 182. The fluid heats as it absorbs heat from the heat exchangers 172 and 182, and exits the heat exchangers 172 and 182, whereupon it returns to the fluid supply systems 174 and 184. The fluid supply systems 174 and 184 preferably cool the fluid and again pump it to the heat exchangers 172 and 182.
Because the gas particle stream is hotter when it passes nearest the cooling system 170 than when it passes nearest the cooling system 180, in most cases the cooling system 170 is required to dissipate more heat than the cooling system 180. Higher rates of fluid flow through a fluid heat exchanger result in higher rates of heat dissipation from that heat exchanger. Therefore, in most circumstances, the rate of fluid flow provided thorough the heat exchanger 172 by the fluid supply system 174 will be higher than correlating flow rate within the cooling system 180.
In a preferred embodiment, the control system 190 is communicatively coupled with the production system 110 and both cooling systems 170 and 180, and can control both the general nature of the particle content produced, as well as the cooling of the conduit 140. Because differing production conditions can lead to different heat loads within the conduit, the control system 190 varies the flow rates within the cooling systems 170 and 180 according to the expected heat load given current production conditions. Furthermore, the control system 190 varies the flow rates based on the temperature of the fluid sensed on output by an optional temperature sensor 192 from each heat exchanger 172 and 182.
Referring now to FIG. 2, the cooling system 200 incorporates the fluid supply system 220, and the heat exchanger 230 formed around the gas transport conduit 210. The heat exchanger 230 comprises the caps 231 and 233, with the outer conduit 232 disposed there-between. The fluid supply system 220 pumps fluid from an outlet 225 and takes fluid into an inlet 224.
As illustrated, the cap 231 includes an inlet 237, and a pressure relief valve 235. The inlet 237 is in fluid communication with a tube structure (discussed below with respect to FIGS. 3-4) disposed inside of the outer conduit 232 and allows fluid to enter the heat exchanger 230. Furthermore, the cap 233 includes an outlet 236, which allows fluid to exit the heat exchanger 230. In alternative embodiments, the inlet and outlet are reversed.
The fluid supply system 220 pumps fluid from is outlet 225 through the fluid line 223 into the inlet 237. Fluid flows through the tube structure within the heat exchanger 230 from the inlet 237. Within the heat exchanger 230, the fluid is heated prior to flowing from the outlet 236. Fluid flowing out of the outlet 236 is channeled through the fluid line 222 into the inlet 224 of the fluid supply system. Because the fluid entering the inlet 224 is preferably hotter than the fluid pumped from the outlet 225, the fluid supply system 220 is preferably configured to cool the received fluid, such as by use of a refrigeration or other cooling system. Because fluid may expand rapidly when heated, the pressure relief valve 235 is provided to relieve pressure within the heat exchanger 230 by permitting outflow of fluid during periods when pressure exceeds a predetermined threshold value. The pressure relief valve can also be mounted through a wall of the outer conduit.
Referring now to FIG. 3, an exemplary heat exchanger 300 is provided. The heat exchanger 300 includes the outer conduit 340 sealed to the gas transport conduit 310 via the caps 320 and 330. The gas transport conduit 310 and the outer conduit 340 form there-between a toroidal chamber 360. Within the toroidal chamber 360, a conductive tube structure 350 is fluidly coupled to a fluid supply system, such as discussed above, thereby allowing fluid to flow from the fluid supply system into and out of the outer conduit 340 via the conductive tube structure 35, and back to the fluid supply system. The conductive tube structure 350 is preferably curved in order to form the toroidal shape of the chamber 360. Furthermore, a static fluid is placed within the space left within the toroidal chamber 360 by the conductive tube structure 350.
Fluid flows through the conductive tube structure 350 within the heat exchanger 300 from the inlet 325 to the outlet 335. As fluid flows through the conductive tube structure 350, it intimately contacts the conductive tube structure 350, which is intimately contacted by the static fluid within the toroidal chamber 360, which in turn is also in intimate contact with the gas transport conduit 310. During operation, hot gas flows through the gas transport conduit 310, thereby heating the gas transport conduit 310. Heat is dissipated from the gas transport conduit 310 through the static fluid within the toroidal chamber 360, into the heat conductive tube structure 350, and then into the fluid flowing there-within. As fluid flows from the inlet 325 to the outlet 335, heat is transferred from the heat conductive tube structure 350 into the fluid, thereby heating the fluid. As heated fluid flows from the outlet 335 back to the fluid supply system, heat is removed from the heat exchanger and thereby removed from the gas transport conduit 310, thereby maintaining it at an operating temperature.
Referring now to FIG. 4, a heat exchanger 400 is provided. The heat exchanger 400 includes the outer conduit 440 sealed to the gas transport conduit 410 via the caps 420 and 430. The gas transport conduit 410 and the outer conduit 440 form there-between a toroidal chamber 460. Within the toroidal chamber 460, a conductive tube structure 450 is fluidly coupled to a fluid supply system, such as discussed above, thereby allowing fluid to flow from the fluid supply system into and out of the outer conduit 440 via the conductive tube structure 450, and back to the fluid supply system. The conductive tube structure 450 is preferably wound spirally around the gas transport conduit 410, thereby forming the toroidal shape of the chamber 460. Furthermore, a static fluid is placed within the space left within the toroidal chamber 460 by the conductive tube structure 450.
Fluid flows through the conductive tube structure 450 within the heat exchanger 400 from the inlet 425 to the outlet 435. As fluid flows through the conductive tube structure 450, it intimately contacts the conductive tube structure 450, which is intimately contacted by the static fluid within the toroidal chamber 460, which in turn is also in intimate contact with the gas transport conduit 410. During operation, hot gas flows through the gas transport conduit 410, thereby heating the gas transport conduit 410. Heat is dissipated from the gas transport conduit 410 through the static fluid within the toroidal chamber 460, into the heat conductive tube structure 450, and then into the fluid flowing there-within. As fluid flows from the inlet 425 to the outlet 435, heat is transferred from the heat conductive tube structure 450 into the fluid, thereby heating the fluid. As heated fluid flows from the outlet 435 back to the fluid supply system, heat is removed from the heat exchanger and thereby removed from the gas transport conduit 410, thereby maintaining it at an operating temperature.
FIG. 5 is a flowchart illustrating one embodiment of a method 500 of cooling a fluid mixture in accordance with the principles of the present invention. As would be appreciated by those of ordinary skill in the art, the protocols, processes, and procedures described herein may be repeated continuously or as often as necessary to satisfy the needs described herein. Additionally, although the steps of method 500 are shown in a specific order, certain steps may occur simultaneously or in a different order than is illustrated. Accordingly, the method steps of the present invention should not be limited to any particular order unless either explicitly or implicitly stated in the claims.
At step 510, a cooling system is provided having a fluid supply system fluidly coupled to a heat exchanger. The heat exchanger comprises an outer conduit and a conductive tube. The outer conduit is disposed around a gas transport conduit and has a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end. The gas transport conduit passes through the first cap into the outer conduit and through the second cap out of the outer conduit. In this respect, the conductive tube passes through the outer conduit. It is contemplated that the conductive tube can pass through portions of the heat exchanger other than the first cap and the second cap in order to pass through the outer conduit. A static fluid chamber is formed between the conductive tube and the gas transport conduit, the static fluid chamber housing a static fluid.
At step 520, a mixture production system produces a fluid mixture. The mixture production system is fluidly coupled to the gas transport conduit. It is contemplated that the fluid mixture can be produced in a variety of ways. However, in a preferred embodiment, the mixture production system energizes a working gas, thereby forming a plasma stream, and applies the plasma stream to powder particles, thereby vaporizing the powder particles and forming the fluid mixture, which comprises vaporized particles.
At step 530, the fluid mixture flows through the gas transport conduit into and out of the outer conduit of the heat exchanger.
At step 540, a circulating fluid flows through the conductive tube into and out of the outer conduit of the heat exchanger. It is noted that this step can occur at the same time that the fluid mixture flows through the heat exchanger at step 530.
At step 550, the gas transport conduit conducts heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber.
At step 560, the conductive tube conducts heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.
At step 570, the heated circulating fluid flows out of the heat exchanger. In a preferred embodiment, the circulating fluid flows back to the fluid supply system, where it is preferably cooled before being recirculated back into the heat exchanger upon repetition of the process.
The present invention has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principles of construction and operation of the invention. As such, references herein to specific embodiments and details thereof are not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications can be made to the embodiments chosen for illustration without departing from the spirit and scope of the invention.

Claims

1. A heat exchanger comprising:

a gas transport conduit providing a channel through which a fluid mixture can flow;

an outer conduit disposed around the gas transport conduit, the outer conduit having a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end, wherein the gas transport conduit passes through the first cap, into the outer conduit, and through the second cap; and

a conductive tube passing through the outer conduit, thereby providing a channel through which a circulating fluid can flow into and out of the outer conduit, wherein a static fluid chamber is formed between the conductive tube and the gas transport conduit, the static fluid chamber configured to house a static fluid,

wherein the gas transport conduit is configured to conduct heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber and the conductive tube is configured to conduct heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.

2. The heat exchanger of claim 1, wherein the conductive tube is wound in a spiral around the gas transport conduit.

3. The heat exchanger of claim 1, wherein the conductive tube passes through the first cap and the second cap.

4. The heat exchanger of claim 1, further comprising a pressure relief valve fluidly coupled to the static fluid chamber, wherein the pressure relief valve is configured to relieve pressure from within the outer conduit by permitting outflow of fluid when a pressure within the outer conduit exceeds a predetermined value.

5. A cooling system comprising:

a fluid supply system having an inlet and an outlet, wherein the fluid supply system is configured to receive a heated circulating fluid through the inlet, cool the heated circulating fluid, and supply the cooled circulating fluid through the outlet;

a conductive tube having a tube inlet fluidly coupled to the outlet of the fluid supply system and a tube outlet fluidly coupled to the inlet of the fluid supply system, wherein the conductive tube passes through the outer conduit, thereby providing a channel through which the circulating fluid can flow from the fluid supply system into the outer conduit via the tube inlet and out of the outer conduit to the fluid supply system via the tube outlet, and wherein a static fluid chamber is formed between the conductive tube and the gas transport conduit, the static fluid chamber configured to house a static fluid,

6. The system of claim 5, wherein the conductive tube is wound in a spiral around the gas transport conduit.

7. The system of claim 5, wherein the conductive tube passes through the first cap and the second cap.

8. The system of claim 5, further comprising a pressure relief valve fluidly coupled to the static fluid chamber, wherein the pressure relief valve is configured to relieve pressure from within the outer conduit by permitting outflow of fluid when a pressure within the outer conduit exceeds a predetermined value.

9. The system of claim 5, wherein a mixture production system is fluidly coupled to the gas transport conduit, the mixture production system configured to produce the fluid mixture and supply the fluid mixture to the gas transport conduit and through the outer conduit.

10. The system of claim 9, wherein the mixture production system is configured to:

energize a working gas to form a plasma stream; and

apply the plasma stream to a plurality of powder particles to vaporize the particles and form the fluid mixture, wherein the fluid mixture comprises the vaporized particles entrained within the plasma stream.

11. The system of claim 10, wherein a sampling system is fluidly coupled to the gas transport conduit and configured to receive the fluid mixture from the outer conduit and to separate condensed particles from the fluid mixture.

12. The system of claim 5, further comprising:

a temperature sensor thermally coupled to the gas transport conduit and configured to sense the temperature of the fluid mixture received from the outer conduit; and

a control system communicatively connected to the temperature sensor and to the fluid supply system, wherein the control system is configured to adjust the flow rate of the circulating fluid from the fluid supply system to the outer conduit based on the temperature of the fluid mixture sensed by the temperature sensor.

13. The system of claim 5, further comprising:

a second fluid supply system having an inlet and an outlet, wherein the second fluid supply system is configured to receive a second heated circulating fluid through the inlet, cool the second heated circulating fluid, and supply the cooled second circulating fluid through the outlet;

a second gas transport conduit fluidly coupled to the gas transport conduit of the outer conduit, thereby providing a channel through which the fluid mixture can flow from the outer conduit;

a second outer conduit disposed around the second gas transport conduit, the second outer conduit having a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end, wherein the second gas transport conduit passes through the first cap, into the second outer conduit, and through the second cap; and

a second conductive tube having a tube inlet fluidly coupled to the outlet of the second fluid supply system and a tube outlet fluidly coupled to the inlet of the second fluid supply system, wherein the second conductive tube passes through the second outer conduit, thereby providing a channel through which the second circulating fluid can flow from the second fluid supply system into the second outer conduit via the tube inlet and out of the second outer conduit to the second fluid supply system via the tube outlet, and wherein a second static fluid chamber is formed between the second conductive tube and the second gas transport conduit, the second static fluid chamber configured to house a second static fluid,

wherein the second gas transport conduit is configured to conduct heat from the fluid mixture in the second gas transport conduit to the second static fluid in the second static fluid chamber and the second conductive tube is configured to conduct heat from the second static fluid in the second static fluid chamber to the second circulating fluid flowing through the second conductive tube.

14. The system of claim 13, further comprising:

a temperature sensor thermally coupled to the second gas transport conduit and configured to sense the temperature of the fluid mixture received from the second outer conduit; and

a control system communicatively connected to the temperature sensor, the fluid supply system and the second fluid supply system, wherein the control system is configured to adjust the flow rate of the circulating fluid from the fluid supply system to the outer conduit and the flow rate of the second circulating fluid from the second fluid supply system to the second outer conduit based on the temperature of the fluid mixture sensed by the temperature sensor.

15. A method of cooling a fluid mixture, the method comprising:

providing an outer conduit and a conductive tube, the outer conduit disposed around a gas transport conduit and having a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end, wherein the gas transport conduit passes through the first cap into the outer conduit and through the second cap, the conductive tube passing through the outer conduit, wherein a static fluid chamber is formed between the conductive tube and the gas transport conduit, the static fluid chamber housing a static fluid,

flowing the fluid mixture through the gas transport conduit into and out of the outer conduit;

flowing a circulating fluid through the conductive tube into and out of the outer conduit;

the gas transport conduit conducting heat from the fluid mixture in the gas transport conduit to the static fluid in the static fluid chamber; and

the conductive tube conducting heat from the static fluid in the static fluid chamber to the circulating fluid flowing through the conductive tube.

16. The method of claim 15, wherein the conductive tube is wound in a spiral around the gas transport conduit.

17. The method of claim 15, wherein the conductive tube passes through the first cap and the second cap.

18. The method of claim 15, wherein a fluid supply system comprises an inlet and an outlet and the method further comprises:

the fluid supply system receiving a heated circulating fluid through the inlet from the outer conduit;

the fluid supply system cooling the heated circulating fluid, thereby forming cooled circulating fluid; and

the fluid supply system supplying the cooled circulating fluid as the circulating fluid to the outer conduit through the outlet.

19. The method of claim 15, wherein a mixture production system is fluidly coupled to the gas transport conduit, the mixture production system configured to produce the fluid mixture and supply the fluid mixture to the gas transport conduit and through the outer conduit.

20. The method of claim 19, further comprising the steps of:

the mixture production system energizing a working gas to form a plasma stream;

the mixture production system applying the plasma stream to a plurality of powder particles, thereby vaporizing the particles and forming the fluid mixture, wherein the fluid mixture comprises the vaporized particles entrained within the plasma stream; and

the mixture production system supplying the fluid mixture to the gas transport conduit in the outer conduit.

21. The method of claim 20, wherein a sampling system is fluidly coupled to the gas transport conduit and configured to receive the fluid mixture from the outer conduit, and wherein the method further comprises the steps of:

the sampling system receiving the fluid mixture from the outer conduit, wherein the fluid mixture comprises condensed particles; and

the sampling system separating the condensed particles from the fluid mixture.

22. The method of claim 15, wherein a temperature sensor is thermally coupled to the gas transport conduit and a control system is communicatively connected to the temperature sensor and to the fluid supply system, and wherein the method further comprises the steps of:

the temperature sensor sensing the temperature of the fluid mixture from the outer conduit;

the control system receiving an indication from the temperature sensor of the sensed temperature; and

the control system adjusting the flow rate of the circulating fluid from the fluid supply system to the outer conduit based on the sensed temperature.

23. The method of claim 15, further comprising the steps of:

providing a second outer conduit and a second conductive tube, the second outer conduit disposed around a second gas transport conduit and having a first end, a second end opposite the first end, a first cap covering the first end, and a second cap covering the second end, the second gas transport conduit fluidly coupled downstream from the gas transport conduit, wherein the second gas transport conduit passes through the first cap into the second outer conduit and through the second cap, the second conductive tube passing through the second outer conduit, wherein a second static fluid chamber is formed between the second conductive tube and the second gas transport conduit, the second static fluid chamber housing a second static fluid,

the second gas transport conduit receiving the fluid mixture from the gas transport conduit of the outer conduit;

flowing the fluid mixture through the second gas transport conduit into and out of the second outer conduit;

flowing a second circulating fluid through the second conductive tube into and out of the second outer conduit; and

the second gas transport conduit conducting heat from the fluid mixture in the second gas transport conduit to the second static fluid in the second static fluid chamber; and the second conductive tube conducting heat from the second static fluid in the second static fluid chamber to the second circulating fluid flowing through the second conductive tube.