HIGH-EFFICIENCY HEAT EXCHANGER AND HIGH-EFFICIENCY HEAT EXCHANGE METHOD

TECHNICAL FIELD

The present invention relates to heat exchange technology having no limitations in application fields. In particular, the present invention is useful not only for heat exchange of gases or liquids of corrosive substances, such as acids and alkalis, but also for temperature control of high-purity water, high-purity silicon compounds used in manufacturing semiconductors, etc. Thus, the present invention is effective in solving the problems with corrosion of devices, etc. and contamination of high-purity substances, which may occur during the heat exchange, and in realizing an improvement of a heat exchange rate.

In other words, the present invention can provide a heat exchanger and a heat exchange method, which ensure high efficiency in general technical fields where temperature adjustment, such as cooling and heating, of substances are needed, while suppressing corrosion of devices and contamination caused by impurities.

It is to be noted that, in this Description, not only an exothermic source, but also an endothermic source are called a “heat source” in some cases. The term “fluid” used in this Description involves a substance that causes a phase change (e.g., a phase change from liquid to gas) with heating or heat absorption.

BACKGROUND ART

A heat exchanger is a device in which two objects having different temperatures are directly or indirectly contacted with each other to heat or cool one of the objects through heat transfer. The heat exchanger is used in cooling steps, heating steps, and refrigeration for industrial purposes in various fields including a boiler, a steam generator, food production, production of chemicals, cold storage, and so on.

Usually, the heat exchanger has a structure depending on characteristics of a substance to be subjected to heat exchange (i.e., a heat exchange target substance). For example, in a heat exchanger for chemicals where heat exchange is performed with respect to highly-corrosive chemicals such as hydrofluoric acid, nitric acid, and sulfuric acid, highly-corrosive fluids such as strong acids and alkalis need to be heated and cooled by employing a heat exchanger having resistance to the chemicals. In that case, heat exchange is typically performed by indirect heating in which a contact portion made of a resin material that is less affected by acids or alkalis is immersed in a heat medium.

FIG. 1 is a schematic view illustrating typical indirect heat exchange. While a heat exchange target fluid (e.g., acid, alkali, or water) is conveyed through a resin-made pipe 1 from an inlet 2 to an outlet 3, heat exchange is performed between the fluid and a heat medium 4, of which temperature is adjusted by a heat source 5, through the resin-made pipe 1. Such a method can improve a heat exchange rate by increasing a surface area of the resin-made pipe 1 contacting with the heat medium 4, e.g., by increasing a length of the pipe 1 immersed in the heat medium 4. However, the cost of an apparatus, including a device for adjusting a fluid temperature in the heat source, containers, etc., may be expensive in some cases. FIG. 2 illustrates a typical example of direct heating in which heat exchange is performed directly with respect to a heat source without intervention of a heat medium. Direct heat exchange is performed by holding a heat source 5 in contact with a pipe 1 made of a material that has high resistance to the heat exchange target fluid and that has good temperature characteristics.

In any type of heat exchange, the following points are required; apparatus components, including the conveying pipe, are not corroded by the heat exchange target fluid or the heat exchange medium, the heat exchange fluid is not contaminated during a heat exchange step, and the heat exchange is performed at high efficiency.

In consideration of those requirements, the conveying pipe is coated with a resin or a ceramic to protect the conveying pipe to be not affected, e.g., corroded, by the heat exchange target fluid or the heat exchange medium.

For example, there is proposed a heat transfer pipe for heat exchange (Patent Document 1), which is disposed in an atmosphere of high-temperature gas and which performs heat exchange between a fluid to be heated, which flows through the heat transfer pipe, and the high-temperature gas, wherein the heat transfer pipe through which the fluid to be heated flows has a three-layer structure in which the pipe is made of a heat-resistant alloy and an outer surface of the heat-resistant heat pipe is covered with a cover member made of a ceramic-alloy composite material with a thermal expansion buffer interposed therebetween, and the ceramic-alloy composite material forming the cover member contains Al and AlN on condition that AlN is 1 wt % or more and 90 wt % or less, and a total rate of (Al+AlN+AlON) is 50 wt % or more and 100 wt % or less.

It is known that a fluorine-based resin has good corrosion resistance and heat resistance to various chemicals. However, when the conveying pipe is made of only the fluorine-based resin, the following drawbacks are caused because the fluorine-based resin is a poor heat conductor in itself. Heat exchange efficiency is low, a longer time is taken to reach a predetermined temperature, and accuracy in temperature control at the predetermined temperature is poor. Aiming to overcome those drawbacks, many proposals have been made in relation to, e.g., the technique of coating the fluorine-based resin over the surface of a metal having good thermal conductivity. For example, a constituent member of equipment using gas is proposed in which at least two layers of coating films, containing a fluorine-based resin, are coated over a substrate (Patent Document 2). The constituent member of equipment using gas is employed in, e.g., a heat exchanger having those coating films in which contents of the fluorine-based resin are gradually increased and contents of inorganic filler are gradually reduced from the lowermost layer film, coated over the substrate, to the uppermost layer film.

Furthermore, there are provided an aluminum alloy member having good corrosion resistance, and a plate-fin type heat exchanger or a plate type heat exchanger in which a heat transfer portion employing a corrosive fluid as a medium is formed using the aluminum alloy member (Patent Document 3). An underlying film made of organic phosphoric acid is coated over a surface of the aluminum alloy member used in the plate-fin type heat exchanger or the plate type heat exchanger including the heat transfer portion in which the corrosive fluid is used as the medium, and a coating film made of a fluorine-based resin paint having an average film thickness of 1 to 100 μm after drying is coated over the underlying film, whereby durability in adhesion of the coating films is improved and high corrosion resistance to a corrosive fluid, e.g., seawater, is obtained.

As described above, a method of coating a resin over a metal having good thermal conductivity is generally proposed. However, because two types of materials have different coefficients of thermal expansion, the coating layers are less adaptable for expansion and contraction, and they may peel off in some cases. This brings about the problem of causing corrosion of metal portions and contamination by metals, etc. Moreover, in the above-described method, the target fluid permeates through pin holes in a resin coating portion, and the above-mentioned problem is similarly unavoidable.

Carbon having good thermal conductivity and corrosion resistance is employed in some cases. For example, there is proposed a block type heat exchanger using a method that is able to heat or cool a large amount of an aqueous solution of hydrogen chloride, containing chlorine, by the heat exchanger without altering a heat transfer surface (Patent Document 4). The heat transfer surface of the heat exchanger is made of carbon impregnated with a fluorine-based resin, and the heat exchanger is constituted by a block made of the carbon impregnated with the fluorine-based resin and arranged within a housing, the block including a flow passage for the aqueous solution of hydrogen chloride through which the aqueous solution of hydrogen chloride flows, and a flow passage for a heat medium through which the heat medium flows.

A heat exchanger made of stainless steel can be used for a heat exchange target substance that is adaptable for a liquid contact portion made of metal. However, a thermal conductivity of stainless steel is relatively low among metals, and a heat source having a large capacity needs to be used to obtain a certain level of heat exchange performance. This brings about the problem that the apparatus body is enlarged and power consumption is increased.

Although, as described above, many proposals trying to use various materials in heat exchangers have been made with intent to obtain high corrosion resistance and to increase the heat exchange efficiency, there is still a demand for development of heat exchange technology that is adaptable particularly for a highly-corrosive substance to be subjected to heat exchange, and that ensures high efficiency of heat exchange.

LIST OF PRIOR-ART DOCUMENTS
Patent Documents

Patent Document 1: Japanese Patent No. 3674401

Patent Document 2: Japanese Patent Laid-Open Publication No. 2004-283699

Patent Document 3: Japanese Patent Laid-Open Publication No. 2008-156748

Patent Document 4: Japanese Patent Laid-Open Publication No. 2006-289799

Patent Document 5: Japanese Patent Laid-Open Publication No. H9-280786

SUMMARY OF THE INVENTION
Problems to be Solved by the Invention

In consideration of the above-described prior art, the present invention provides a heat exchanger that has high heat exchange performance and high corrosion resistance with respect to a heat exchange target fluid.

A prior-art heat exchanger generally employs a method of performing heat exchange by contacting a member, which is held in contact with a heat exchange target fluid during the heat exchange of the fluid, with a heat medium such as a heat source or a coolant. A material of the contact member is selected depending on characteristics the fluid. However, the selected material of the contact member does not always have good thermal conductivity. In some cases, the disadvantage of the member having low thermal conductivity has to be compensated for by employing, e.g., many electric heaters as heat sources, or an electric heater having a large capacity. This often results in a decrease of energy efficiency in the heat exchange and an increase of the apparatus size.

The present invention is featured in that heat exchange can be performed at high efficiency even when the material of the contact portion is selected with attention focused only to characteristics of the heat exchange target fluid. In addition, according to the present invention, a compact product can be obtained at a relatively low cost without increasing the apparatus size. An object of the present invention is to provide a high-efficiency heat exchanger that can be applied to a wide range of fields regardless of the type of heat exchange target fluid. Another object of the present invention is to provide a heat exchanger in which corrosion of components caused by the heat exchange target fluid is avoided, and the fluid having been subjected to the heat exchange is not contaminated. Still another object of the present invention is to provide a heat exchanger which has superior heat conduction characteristics in heating or cooling highly-corrosive aqueous solutions and gases, e.g., hydrofluoric acid and hydrogen chloride, and alkaline aqueous solutions, e.g., sodium hydroxide. Still another object of the present invention is to provide a heat exchange technique that enables heat exchange to be performed at high efficiency while high purity of the heat exchange target fluid is maintained.

Means for Solving the Problems

The present invention is constituted by the following technical matters.

[1] A heat exchanger comprising a heat source, a heat transfer structure contacting with a heat exchange target fluid, and a heat transfer member that transfers heat from the heat source to the heat transfer structure, thus performing heat-transfer type heat exchange through a contact surface of the heat transfer structure with the heat exchange target fluid, wherein the heat transfer structure includes a body having an inlet, an outlet, and a flow passage for the heat exchange target fluid, and many heat conductors mounted to the body, an inner wall surface of the flow passage for the heat exchange target fluid, the inner wall surface defining a contact surface with the heat exchange target fluid, is made of a material stable against the heat exchange target fluid, the heat conductors are made of a material having a higher thermal conductivity than a material of the body, and the heat conductors are mounted near the flow passage for the heat exchange target fluid at positions where the heat conductors are not contacted with the heat exchange target fluid.

[2] The heat exchanger according to [1], wherein the many heat conductors involve a plurality of heat conductors arranged in opposing relation on both sides of the flow passage for the heat exchange target fluid.

[3] The heat exchanger according to [1] or [2], wherein the heat transfer member comprises two heat transfer members sandwiching the body, and one or more of the heat conductors extend from each of the two heat transfer members. Here, the mode of extension of the heat conductors includes not only the case where the heat transfer member and the heat conductors are formed integrally with each other, but also the case where the heat conductors are mounted as separate components to the heat transfer member.

[4] The heat exchanger according to any one of [1] to [3], wherein the heat conductor has a pin-like configuration.

[5] The heat exchanger according to [4], wherein at least part of the many heat conductors is formed integrally with the heat transfer member having a plate-like shape.

[6] The heat exchanger according to [4] or [5], wherein at least part of the many heat conductors has an outer surface of a zigzag configuration. Preferably, more than the half of the many heat conductors has the outer surface of the zigzag configuration.

[7] The heat exchanger according to [6], wherein the zigzag configuration is formed such that a surface area of the outer surface is 1.5 to 3 times a surface area of the outer surface including no protrusions of the zigzag configuration.

[8] The heat exchanger according to Claim [6] or [7], wherein the heat conductor having the outer surface of the zigzag configuration is a screw.

[9] The heat exchanger according to [8], wherein the heat conductor having the outer surface of the zigzag configuration is a flat-head screw.

[10] The heat exchanger according to any one of [1] to [9], wherein the flow passage for the heat exchange target fluid has a plurality of bent portions.

[11] The heat exchanger according to [10], wherein the flow passage for the heat exchange target fluid has a returning bent portion for turning an extending direction of the flow passage to be returned toward an inlet side.

[12] The heat exchanger according to any one of [1] to [11], wherein at least part of the heat conductors arranged on a side nearer to the inlet is made of a material having a higher thermal conductivity than a material of the heat conductors arranged on a side farther away from the inlet. Here, the side nearer to the inlet implies, for example, a region spanning ½, ⅓ or ¼ of an overall length of the flow passage from the inlet. The side farther away from the inlet implies a region similarly spanning from the outlet.

[13] The heat exchanger according to any one of [1] to [12], wherein the heat conductors are arranged in a larger number and at a higher density on a side nearer to the inlet than on a side farther away from the inlet.

[14] The heat exchanger according to [12] or [13], wherein the outlet is a discharge port in communication with outside.

[15] A heat exchanger wherein the heat exchanger according to any one of [1] to [13] is stacked plural.

[16] The heat exchanger according to any one of [1] to [15], wherein the inner wall surface of the flow passage for the heat exchange target fluid is made of resin.

[17] The heat exchanger according to any one of [1] to [15], wherein the inner wall surface of the flow passage for the heat exchange target fluid is made of metal or carbon.

[18] The heat exchanger according to any one of [1] to [17], wherein the many heat conductors involve heat conductors made of copper and heat conductors made of aluminum.

[19] The heat exchanger according to any one of [1] to [18], wherein the heat source is an exothermic source.

[20] The heat exchanger according to any one of [1] to [18], wherein the heat source is an endothermic source.

[21] A heat exchange method wherein heat-transfer type heat exchange is performed with respect to a fluid by employing the heat exchanger according to any one of [1] to [20].

[22] A heat exchange method of performing heat-transfer type heat exchange with respect to a fluid by employing the heat exchanger according to [12], wherein the method comprises the steps of the heat conductors, which are made of a material having a relatively higher thermal conductivity than those on a side farther away from the inlet, on a side nearer to the inlet, and arranging the heat conductors, which are made of a material having a relatively lower thermal conductivity than those on a side nearer to the inlet, on a side farther away from the inlet, thereby variations in temperature distribution occurred between an upstream side and a downstream side of the flow passage for the heat exchange target fluid are suppressed.

[23] A heat exchange method of performing heat-transfer type heat exchange with respect to a fluid by employing the heat exchanger according to [13], wherein the method comprises the steps of the heat conductors, which are made of a material having a relatively higher thermal conductivity than those on a side farther away from the inlet, on a side nearer to the inlet, and arranging the heat conductors, which are made of a material having a relatively lower thermal conductivity than those on a side nearer to the inlet, on a side farther away from the inlet, thereby variations in temperature distribution occurred between an upstream side and a downstream side of the flow passage for the heat exchange target fluid are suppressed.

[24] A heat exchange method of performing heat-transfer type heat exchange with respect to a corrosive fluid by employing the heat exchanger according to [16].

From another aspect, the present invention is constituted by the following technical matters.

(1) A heat exchanger comprising a flow passage through which a heat exchange target fluid flows, and a heat transfer structure that is contacted with the heat exchange target fluid flowing through the flow passage, thus performing heat-transfer type heat exchange through a contact surface of the heat transfer structure with the heat exchange target fluid, wherein:

(a) a surface of the heat transfer structure, the surface defining the contact surface with the heat exchange target fluid, is made of a material stable against the heat exchange target fluid,

(b) heat conductors are mounted to the heat transfer structure, and are made of a material having a higher thermal conductivity than a material of the heat transfer structure, and

(c) the heat conductors are mounted near the contact surface of the heat transfer structure with the heat exchange target fluid at positions where the heat conductors are not contacted with the heat exchange target fluid,

whereby heat conduction efficiency is increased at the contact surface of the heat transfer structure with the heat exchange target fluid.

(2) The heat exchanger according to (1), wherein the heat conductor has a pin-like configuration. Here, the pin-like configuration involves, for example, not only a circular columnar shape and a polygonal pillar shape, but also the case where an outer surface of the heat conductor has a zigzag configuration.

(3) The heat exchanger according to (1) or (2), wherein the heat conductor has a surface of a zigzag configuration.

(4) The heat exchanger according to any one of (1) to (3), wherein the contact surface of the heat transfer structure with the heat exchange target fluid has a zigzag configuration.

(5) The heat exchanger according to any one of (1) to (4), wherein the flow passage for the heat exchange target fluid has a returning configuration to make the heat exchange target fluid turbulent and to increase efficiency of heat transfer.

(6) The heat exchanger according to any one of (1) to (5), wherein the flow passage is constituted such that a diameter and/or an overall length of the flow passage is changeable.

(7) The heat exchanger according to any one of (1) to (6), wherein the heat exchange target fluid is gas or a liquid.

(8) The heat exchanger according to any one of (1) to (7), wherein a material of the heat transfer structure is resin or metal.

(9) The heat exchanger according to any one of (1) to (8), wherein the heat conductor is made of metal having a higher thermal conductivity than a material of the heat transfer structure.

(10) A heat exchange method of contacting a heat transfer structure with a heat exchange target fluid, thus performing heat-transfer type heat exchange through a contact surface of the heat transfer structure with the heat exchange target fluid, wherein:

(a) a surface of the heat transfer structure, the surface defining the contact surface with the heat exchange target fluid, is made of a material stable against the heat exchange target fluid,

(b) heat conductors are mounted to the heat transfer structure, and are made of a material having a higher thermal conductivity than a material of the heat transfer structure, and

whereby heat conduction efficiency is increased at the contact surface of the heat transfer structure with the heat exchange target fluid.

(11) The heat exchange method according to (10), wherein the heat conductor has a pin-like configuration.

(12) The heat exchange method according to (10) or (11), wherein the heat conductor has a surface of a zigzag configuration.

(13) The heat exchange method according to any one of (10) to (12), wherein the contact surface of the heat transfer structure with the heat exchange target fluid has a zigzag configuration.

(14) The heat exchange method according to any one of (10) to (13), wherein the flow passage for the heat exchange target fluid has a returning configuration to make the heat exchange target fluid turbulent and to increase efficiency of heat transfer.

(15) The heat exchange method according to any one of (10) to (14), wherein the flow passage is constituted such that a diameter and/or an overall length of the flow passage is changeable.

(16) The heat exchange method according to any one of (10) to (15), wherein the heat exchange target fluid is gas or a liquid.

(17) The heat exchange method according to any one of (10) to (16), wherein a material of the heat transfer structure is resin or metal.

(18) The heat exchange method according to any one of (10) to (17), wherein the heat conductor is made of metal having a higher thermal conductivity than a material of the heat transfer structure.

Advantageous Effects of the Invention

The following advantageous effects are obtained with the present invention.

Because acids and alkalis vigorously react with metals, the metals cannot be used in a portion contacting with the acids and the alkalis. For that reason, heat exchangers using resins in contact portions have been used so far. However, because thermal conductivities of resins are low, thermal efficiency is poor, and an apparatus structure is increased in size and complicacy. According to the present invention, a heat exchanger having high heat exchange efficiency and a compact structure can be provided. Furthermore, since reaction between the heat exchanger and the heat exchange target fluid, such as acid and alkali, is avoided, temperatures of high-purity acid, alkali, etc. can be adjusted without contamination by a trace ingredient. Moreover, the present invention can be applied to other substances, such as high-purity water, than the acids and the alkalis regardless of whether the substances are in a liquid or gaseous state.

By utilizing fluid dynamics and thermodynamics and by employing the direct heating method, the present invention can further provide a heat exchange technique, which ensures savings in electric power and space, and high heat exchange efficiency even when the portion contacting with the heat exchange target fluid is entirely made of resin.

In addition, heat exchange performance of 80% or more is realized with a configuration to directly perform the heat exchange on condition that the portion contacting with the heat exchange target fluid is metal-free. Thus, it can be said that the present invention provides a heat exchanger having prominent performance in comparison with the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating heat exchange by typical indirect heating according to prior art.

FIG. 2 is a schematic view illustrating heat exchange by typical direct heating according to prior art.

FIG. 3 is a schematic sectional view illustrating one example of a heat transfer-type heat exchanger using a plurality of independent heat conductors.

FIG. 4 is a schematic sectional view illustrating one example of a heat transfer-type heat exchanger in which a plurality of heat conductors is integrated with a heat transfer plate.

FIG. 5 is a schematic sectional view illustrating one example of a heat transfer-type heat exchanger using a heat conductor that has a zigzag surface configuration.

FIG. 6 is a schematic sectional view illustrating one example of a heat transfer-type heat exchanger in which a flow passage for a heat exchange target fluid has a zigzag shape.

FIG. 7 illustrates a sectional structure of a heat exchanger according to Embodiment 1 of the present invention; specifically, FIG. 7-1 illustrates a section taken along a vertical plane (vertical direction), and FIG. 7-2 illustrates a section taken along a horizontal plane (horizontal direction).

FIG. 8 illustrates layout of an apparatus used for testing heat exchange performance.

FIG. 9 illustrates a temperature distribution confirmed by thermography, and represents that temperature rises in darker regions where the heat conductors are mounted, in comparison with the ambient temperature.

FIG. 10 illustrates a relationship between measured values of an outlet gas temperature and a setting temperature, the relationship being obtained from test results.

FIG. 11 comparatively illustrates heat exchange performance obtained with heat exchange through resin and heat exchange through a metal surface according to the present invention.

FIG. 12 is a schematic sectional view to explain a zigzag configuration of the flow passage for the heat exchange target fluid; specifically, FIG. 12(a) is a sectional view to explain the case of doubling a surface area, and FIG. 12(b) is a sectional view to explain adjustment of a pitch depth.

FIG. 13 is a schematic sectional view illustrating layout variations of the heat conductors. Specifically, FIG. 13(a) illustrates a layout example in which two heat conductors sandwiching a flow passage for the heat exchange target fluid therebetween are disposed to extend from above. FIG. 13(b) illustrates a layout example in which two heat conductors sandwiching the flow passage for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 13(c) illustrates a layout example in which four heat conductors sandwiching the flow passage for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 13(d) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 13(a) have zigzag configurations. FIG. 13(e) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 13(b) have zigzag configurations. FIG. 13(f) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 13(c) have zigzag configurations.

FIG. 14 illustrates structural examples in which the heat transfer plate and the plural heat conductors in FIG. 13 are formed integrally with each other. Specifically, FIG. 14(a) illustrates a layout example in which two heat conductors sandwiching the flow passage for the heat exchange target fluid therebetween are disposed to extend from above. FIG. 14(b) illustrates a layout example in which two heat conductors sandwiching the flow passage for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 14(c) illustrates a layout example in which four heat conductors sandwiching the flow passage for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 14(d) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 14(a) have zigzag configurations. FIG. 14(e) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 14(b) have zigzag configurations. FIG. 14(f) illustrates a structural example in which outer surfaces of the heat conductors in the layout example of the heat conductors in FIG. 14(c) have zigzag configurations.

FIG. 15 is an illustration to explain a temperature distribution when heat conductors made of different materials are arranged; specifically, FIG. 15(a) depicts a plan view and a temperature distribution image when heat conductors of the same type are arranged, and FIG. 15(b) depicts a plan view and a temperature distribution image when heat conductors made of different materials are mounted.

FIG. 16 is a plan view of a heat exchanger in which heat conductors are arranged at different densities between the upstream side and the downstream side.

FIG. 17 illustrates a sectional structure of a heat exchanger equipped with a shower head according to the present invention; specifically, FIG. 17(a) illustrates a section taken along a horizontal plane (horizontal direction), and FIG. 17(b) illustrates a section taken along a vertical plane (vertical direction).

FIG. 18 is a side view of a multi-stage heat exchanger that is constituted by stacking the heat exchangers each illustrated in FIG. 7.

FIG. 19 illustrates a configuration of a temperature-controlled supply apparatus according to Embodiment 2 of the present invention.

MODE FOR CARRYING OUT THE INVENTION

The present invention relates to a heat exchanger and a heat exchange method, the heat exchanger comprising a flow passage through which a heat exchange target fluid flows, and a heat transfer structure that is contacted with the heat exchange target fluid flowing through the flow passage, thus performing heat-transfer type heat exchange through a contact surface of the heat transfer structure with the heat exchange target fluid, wherein:

(1) a surface of the heat transfer structure, the surface defining the contact surface with the heat exchange target fluid, is made of a material stable against the heat exchange target fluid,

(2) the heat transfer structure includes heat conductors that are mounted to the heat transfer structure, and that are made of a material having a higher thermal conductivity than a material of the heat transfer structure, and

(3) the heat conductors are mounted near the contact surface of the heat transfer structure with the heat exchange target fluid at positions where the heat conductors are not contacted with the heat exchange target fluid,

whereby heat conduction efficiency is increased at the contact surface of the heat transfer structure with the heat exchange target fluid.

In the present invention, the heat conductors made of a material having a higher thermal conductivity than that of the heat transfer structure (particularly, its portion contacting with the heat exchange target fluid) are mounted in the heat transfer structure, which is made of a substance (material) neither affecting nor affected by the heat exchange target fluid, at positions where the heat conductors are not contacted with the fluid. The heat exchange target fluid can be efficiently heated or cooled by heating or cooling the heat transfer structure and transferring heat from a heat source to the heat exchange target fluid.

In general, liquids and gases having various characteristics are employed as the heat exchange target fluids that are heated or cooled by heat exchangers. For example, aqueous solutions of acids or alkalis are used in chemical reactions, etching processes, and so on. However, because acids and alkalis vigorously react with metals, the metals cannot be used in a portion contacting with the acids and the alkalis in many cases. Resins are used in some products of heat exchangers that are used for heat exchange of those reactive heat exchange target fluids. However, because thermal conductivities of resins are low, heat exchange efficiency is poor, necessary electric power is increased, and shapes and structures of the heat exchangers are increased in size and complicacy in many cases.

The heat exchanger according to the present invention employs the direct heating method and undergoes no limitations on materials of a surface of the heat transfer structure, the surface defining the contact surface with the heat exchange target fluid, insofar as the material is stable against the heat exchange target fluid. For example, a heat exchanger ensuring savings in electric power and space and having good thermal efficiency of 80% or more can be provided regardless of that the portion contacting with the heat exchange target fluid is entirely made of resin.

[Heat Exchange Target Fluid]

The heat exchange target fluid used in the present invention is not limited to particular one. Examples of the heat exchange target fluid are solutions or gases of corrosive acids such as hydrochloric acid, sulfuric acid, nitric acid, chromic acid, phosphoric acid, hydrofluoric acid, acetic acid, perchloric acid, hydrobromic acid, silicon fluoride acid, and boric acid, alkalis such as ammonia, potassium hydroxide, and sodium hydroxide, and metal salts such as silicon chloride, as well as high-purity water. Those heat exchange target fluids are used as materials to progress reactions with other substances, or chemicals, e.g., an etchant, employed in reaction steps, and they are used for intended purposes under control to proper temperatures by heat exchangers. The heat exchanger according to the present invention can perform heating, cooling, or temperature control of those heat exchange target fluids at high efficiency in a state free from contamination caused by trace impurities.

[Heat Transfer Structure]

The heat transfer structure used in the present invention has a surface defining the contact surface with the heat exchange target fluid, and heat conductors. The contact surface of the heat transfer structure with the heat exchange target fluid is made of a material stable against the heat exchange target fluid. In other words, the material of the contact surface is selected such that the surface of the heat transfer structure and the heat exchange target fluid will not react with each other in a temperature range where the heat exchange is performed, or that ingredients of the heat transfer structure will not elute from the surface in such a temperature range. Reactivity (corrosiveness) of the heat exchange target fluid is different depending on the material of the surface of the heat transfer structure, a contact temperature, etc. Furthermore, an allowable range of purity after the heat exchange is different depending on the use and properties of the heat exchange target fluid. Therefore, the material of the heat transfer structure cannot be specified indiscriminately. In metal halides and etchants used in manufacturing semiconductor devices, for example, because high-purity substances are employed, a reduction of purity attributable to the heat exchange process is not allowed. On the other hand, in heat exchangers for turbines, a change in purity of the heat exchange target fluid attributable to the heat exchange process is insignificant in many cases.

The substance (material) of a member forming the surface of the heat transfer structure, which is contacted with the heat exchange target fluid, is optionally selected from metals such as iron, carbon steel, stainless steel, aluminum, and titanium, synthetic resins such as a fluorine-based resin and polyester, and ceramics. When highly-corrosive acids are subjected to heat exchange, the fluorine-based resin is preferably used. Examples of the fluorine-based resin are polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylfluoride (PVF), fluorinated polypropylene (FLPP), and polyvinylidene fluoride (PVDF).

In the heat exchanger according to the present invention, the heat transfer structure includes the heat conductors made of a material having a higher thermal conductivity than that of the heat transfer structure (particularly, its portion contacting with the heat exchange target fluid). The heat conductors are mounted near the contact surface of the heat transfer structure with the heat exchange target fluid (i.e., near a flow passage for the heat exchange target fluid) at the positions where the heat conductors are not contacted with the heat exchange target fluid.

One exemplary configuration of the heat transfer structure will be described below with reference to FIG. 3. A heat exchanger 101 illustrated in FIG. 3 includes a heat transfer structure 6 having a body 61, heat conductors 62, a heater plate 51 serving as a heat source, heat transfer plates 52a and 52b, and a flow passage 7 for the heat exchange target fluid. Heat from the heater plate 51 is diffused into the heat transfer structure 6 (including the body 61 and the heat conductors 62) through the heat transfer plates 52a and 52b. The body 61 and the heat conductors 62 are heated by the diffused heat and, at the same time, the heat exchange target fluid passing through the flow passage 7 is also heated by the diffused heat through a contact surface 63. Dotted-line arrows in FIG. 3 represent transfer of heat from the body 61. Because the material of the heat conductors 62 has a higher thermal conductivity than that of the body 61, temperatures of the heat conductors 62 rise more quickly than that of the body 61, and the heat exchange with respect to the heat exchange target fluid can be performed efficiently. The heat conductors 62 are embedded in the body 61 in a state contacting with the heat transfer plate 52a or the heater plate 51. To increase efficiency of the heat exchange, the heat conductors 62 and the flow passage 7 are preferably positioned as close as possible. An inner wall surface of the flow passage 7 is preferably a flat or curved surface having no irregularities from the viewpoint of maintenance, but it preferably has a zigzag configuration from the viewpoint of increasing heat exchange performance.

As illustrated in FIG. 3, the heat conductors 62 each having a columnar shape can be mounted by individually inserting the heat conductors 62 into holes formed in the body 61. Alternatively, as illustrated in FIG. 4, the heat transfer plate 52 and the plural heat conductors 62 may be formed integrally with each other, and the heat conductors 62 may be mounted by collectively inserting the heat conductors 62 into holes formed in the body 61. The positions and the number of the mounted heat conductors 62 are determined in consideration of heat exchange efficiency, etc. By increasing surface areas of the heat conductors 62, heat can be uniformly and efficiently diffused from the heat conductors 62. The surface area of each heat conductor 62 is preferably increased by forming the heat conductor 62 such that its outer surface has a zigzag configuration as illustrated in FIG. 5. Stated in another way, an outer surface of the heat conductor 62 is preferably formed to have a configuration that annular mountains are continuously arranged in the lengthwise direction of the heat conductor 62 (i.e., a configuration that mountains and valleys are alternately arranged in a continuous way). The “configuration that annular mountains are continuously arranged” involves the case where the mountains and the valleys are spirally formed like thread ridges and grooves. More preferably, the zigzag configuration is formed such that a surface area of the outer surface of the heat conductor 62 is, e.g., 1.5 to 3 times a surface area of a column having the same diameter as the heat conductor 62, but not including the mountains (protrusions). When the body 61 is made of resin, the heat conductor 62 having the zigzag configuration can be mounted in place by a method of mounting the heat conductor 62 in a state where the resin is still soft before hardening, and then hardening the resin, or a method of forming a hole in the hardened resin by, e.g., a drill, and then screwing the heat conductor having the zigzag configuration into the hole. When the body 61 is made of metal, the heat conductor 62 is mounted by forming a hole with drilling in most cases.

FIG. 13 is a schematic sectional view illustrating layout variations of the heat conductors 62.

FIG. 13(
a) illustrates a layout example in which two heat conductors 62 sandwiching the flow passage 7 for the heat exchange target fluid therebetween are disposed to extend from above. FIG. 13(b) illustrates a layout example in which two heat conductors 62 sandwiching the flow passage 7 for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 13(c) illustrates a layout example in which four heat conductors 62 sandwiching the flow passage 7 for the heat exchange target fluid therebetween are disposed to extend from above and below. FIG. 13(d) illustrates a structural example in which outer surfaces of the heat conductors 62 in the layout example of the heat conductors 62 in FIG. 13(a) have zigzag configurations. FIG. 13(e) illustrates a structural example in which outer surfaces of the heat conductors 62 in the layout example of the heat conductors 62 in FIG. 13(b) have zigzag configurations. FIG. 13(f) illustrates a structural example in which outer surfaces of the heat conductors 62 in the layout example of the heat conductors 62 in FIG. 13(c) have zigzag configurations. In any of the configurations illustrated in FIGS. 13(a) to 13(f), the plural heat conductors 62 are arranged in opposing relation on both sides of the flow passage 7 for the heat exchange target fluid.

In any of the configurations illustrated in FIGS. 13(a) to 13(f), a heat exchanger includes heater plates 51a and 51b, heat transfer plates 52a and 52b, a body 61, and the flow passage 7 for the heat exchange target fluid. Because the above-mentioned components are similar to those in the heat exchanger 101 in FIGS. 3 and 5 except for including two heater plates, descriptions of those components are omitted here. It is to be noted that, in FIGS. 13(a) to 13(d), the lower heater plate 51b may be dispensed with.

FIG. 14 illustrates structural examples in which the heat transfer plate 52 and the plural heat conductors 62 in FIG. 13 are formed integrally with each other. In any of the configurations illustrated in FIGS. 14(a) to 14(f), the plural heat conductors 62 are arranged in opposing relation on both sides of the flow passage 7 for the heat exchange target fluid. Because the configuration illustrated in FIG. 14 is similar to that illustrated in FIGS. 4 and 13 except that the heat transfer plate 52 and the plural heat conductors 62 are formed integrally with each other, detailed description of the configuration illustrated in FIG. 14 is omitted here.

FIG. 15 is an illustration to explain a temperature distribution when heat conductors made of different materials are arranged. Specifically, FIG. 15(a) depicts a plan view and a temperature distribution image when the heat conductors 62 of the same type are arranged, and FIG. 15(b) depicts a plan view and a temperature distribution image when the heat conductors 62 made of different materials are mounted.

In any of heat exchangers 104 illustrated in FIGS. 15(a) and 15(b), a number 135 of mount holes into which the heat conductors 62 are inserted are formed in the heat transfer plate 52 and the body 61 (not illustrated) substantially at equal intervals. The heat conductors 62 are each detachably mounted into the mount holes of the heat transfer plate 52 and the body 61. For example, each heat conductor 62 may be formed in the shape of a screw having a flat head, and may be mounted to the mount hole by screwing the heat conductor 62. A large number of heat conductors 62 may be constituted as a combination of heat conductors 62 made of different materials. By combining the heat conductors 62 made of different materials, it is possible to eliminate variations in the temperature distribution, which occur between the upstream side and the downstream side of the flow passage 7. In addition, a manufacturing cost can be reduced by arranging the heat conductors 62 made of an expensive material only at necessary places, and arranging the heat conductors 62 made of an inexpensive material at other places.

In FIG. 15(a), all the heat conductors 62 are formed of aluminum pins. In FIG. 15(b), the heat conductors 62 until the fifth column counting from left are formed of aluminum pins, and the heat conductors 62 after the sixth column counting from left are formed of copper pins. Stated in another way, a number 135 of aluminum pins are mounted as the heat conductors 62 in FIG. 15(a), while a number 45 of copper pins are mounted as the heat conductors 62 on the upstream side and aluminum pins are mounted on the downstream side in FIG. 15(b).

On the right side of FIGS. 15(a) and 15(b), temperature distribution images are depicted. In FIG. 15(a), temperature is relatively low in a left half and is relatively high in a right half. On the other hand, in FIG. 15(b), variations in the temperature distribution are eliminated considerably. Thus, variations in the temperature distribution between the upstream side and the downstream side can be reduced by arranging the heat conductors 62 made of a material having a high thermal conductivity on the upstream side, and the heat conductors 62 made of a material having a relatively low thermal conductivity on the downstream side. With a reduction of the variations in the temperature distribution, distortions of the body, the heat transfer plates, etc. can be suppressed, and shortening of the heater lifetime can be prevented. Furthermore, in the case of treating a fluid that causes thermal denaturation when a temperature difference (ΔT) between temperature of the fluid passing through an inlet and temperature of the fluid passing through an outlet increases, it has been needed so far to heat the fluid to such an extent that an output is reduced not to excessively increase ΔT. In contrast, high-efficiency heat exchange can be performed with the heat exchanger according to the present invention in which the variations in the temperature distribution are reduced.

FIG. 16 is a plan view of a heat exchanger 104 in which heat conductors 62 are arranged at different densities between the upstream side and the downstream side. In the heat exchanger 104 of FIG. 16, all the heat conductors 62 are formed of aluminum pins. The other configurations of the heat transfer plate 52, the body 61, etc. are similar to those in the heat exchanger 104 of FIG. 15. In FIG. 16, nine heat conductors 62 are arranged in the up-and-down direction until the fifth column counting from left, and four or five heat conductors 62 are arranged in the up-and-down direction in the sixth to fifteenth columns counting from left. Thus, the variations in the temperature distribution between the upstream side and the downstream side can also be reduced by arranging the heat conductors 62 at a higher density on the upstream side, and the heat conductors 62 at a lower density on the downstream side. In the heat exchanger 104 of FIG. 16, the heat conductors 62 made of materials having different thermal conductivities may be arranged on the upstream side and the downstream side such that the variations in the temperature distribution between the upstream side and the downstream side are adjusted more finely.

FIG. 17 illustrates a sectional structure of a heat exchanger 105 equipped with a shower head. Specifically, FIG. 17(a) illustrates a section taken along a horizontal plane (horizontal direction), and FIG. 17(b) illustrates a section taken along a vertical plane (vertical direction). The heat exchanger 105 equipped with the shower head has a body 61 including a heater plate 51, a heat transfer plate 52, many heat conductors 62, and a flow passage 7 for the heat exchange target fluid. Many discharge ports 75 communicating with the flow passage 7 are formed in the body 61. The heat exchanger 105 equipped with the shower head further includes two inlets 83a and 83b. A heat exchange target fluid 73 having entered the flow passage 7 through the inlets is discharged from the discharge ports 75 after being heated. Thus, in the heat exchanger 105 equipped with the shower head, the discharge ports 75 communicating with the outside serve as outlets.

The many heat conductors 62 are constituted by copper-made pin-like members arranged on the upstream side nearer to the inlets 83a and 83b, and aluminum-made pin-like members arranged on the downstream side, as in the configuration of FIG. 15(b), such that variations in temperature distribution over the entire length of the flow passage 7 is minimized. Stated in another way, the copper-made pin-like members are mainly arranged in regions closer to both the right and left sides of the body 61, and the aluminum-made pin-like members are mainly arranged in a central region of the body 61. Furthermore, many bent portions 71 are formed in the flow passage 7 such that the heat exchange target fluid strikes against a flow passage wall in the bent portions 71 to generate turbulent streams, thereby eliminating unevenness in heating. Accordingly, the fluids substantially at the same temperature are discharged from the many discharge ports 75. While the heat exchanger 105 equipped with the shower head is mainly used to provide a gas shower for discharging gas, a liquid may be discharged in some cases.

The heat exchanger 105 equipped with the shower head may be constituted in multiple stages by arranging one or a plurality of heat exchangers equipped with no shower heads in an upper stage, and by connecting two inlets of the heat exchanger 105 equipped with the shower head to an outlet of the heat exchanger in the upper stage through a branching pipe (see FIG. 18 described later).

FIG. 6 is a schematic sectional view illustrating principal parts of a cylindrical heat exchanger 102 embodying the present invention. A heat transfer structure 6 including a heat conductor 62 and a body 61 is disposed on an inner surface of a cylindrical heat source 5. The heat conductor 62 has a zigzag-shaped surface that is positioned on the side facing a flow passage, and a flat surface that is held in contact with the heat source 5. The body 61 covers a surface of the heat conductor 62 to define the flow passage 7, and it is contacted with the heat exchange target fluid. Here, the body 61 is preferably provided as a thin film that is formed on the surface of the heat conductor 62. A surface of the body 61 contacting with the heat exchange target fluid is preferably formed in a zigzag shape similar to that of the heat conductor 62. The heat exchange efficiency at the body surface is improved by forming the body surface in a zigzag shape so as to increase a contact surface area.

FIG. 12 is a schematic sectional view to explain a zigzag configuration of the flow passage for the heat exchange target fluid. Specifically, FIG. 12(a) is a sectional view to explain the case of doubling a surface area, and FIG. 12(b) is a sectional view to explain adjustment of a pitch depth.

FIG. 12(
a) illustrates an example in which an inner surface of the heat transfer structure 6 contacting with the heat exchange target fluid 73 has such a zigzag configuration that regular triangles with one side being 2 mm are continuously arranged along its cross-section. In other words, the inner surface of the heat transfer structure 6 has a configuration that annular mountains are continuously arranged in the lengthwise direction of the heat transfer structure 6. With the zigzag configuration described above, the surface area of the inner surface of the heat transfer structure 6 is increased twice that of a flat inner surface of the heat transfer structure not having the zigzag configuration. As a result, the heat exchange efficiency can be doubled. The zigzag configuration of the heat transfer structure 6 is not limited to that illustrated in FIG. 12, and the present invention disclosed here involves the case of forming the zigzag configuration such that the surface area of the inner surface of the heat transfer structure 6 is increased 1.5 to 3 times, for example.

While the heat exchange efficiency is increased as the surface area of the inner surface of the heat transfer structure 6 increases, it is not always preferable to increase the surface area as far as possible depending on properties of the heat exchange target fluid, such as a flow rate and viscosity. The left side of FIG. 12(b) illustrates a state where gaps 74 are generated between the inner surface of the heat transfer structure 6 and the fluid 73. In that state, because non-contact portions are generated between the inner surface of the heat transfer structure 6 and the fluid 73, the heat exchange efficiency is reduced. Thus, when generation of the non-contact portions due to the presence of the gaps 74 is estimated, it is needed to make adjustment not to generate the non-contact portions by increasing the pitch (groove size) of the zigzag configuration. The cylindrical heat exchanger 102 may be constituted in a detachable manner, and the plural cylindrical heat exchangers 102 having different pitches may be prepared.

[Material of Heat Conductor and Distance Between Heat Conductor and Heat Exchange Target Fluid]

The heat conductor 62 is made of a material having a higher thermal conductivity than that of the body 61. However, the expression “a higher thermal conductivity” implies a relative value in terms of comparison between conductivities of both the materials, and it does not imply a specific absolute value. The thermal conductivity is usually given as about 0.2 W/m·k for plastic, about 0.25 for a fluorine-based resin, about 47 for carbon steel, about 15 for stainless steel, 237 for aluminum, 386 for pure copper, and about 1 for PYREX (registered trademark) glass, for example. From the above-mentioned materials, proper ones may be selected in consideration of relative thermal conductivities. Because the fluorine-based resin has a minimum value, the heat exchange efficiency is increased regardless of which one of those materials is selected as the heat conductor, when the body 61 is made of the fluorine-based resin. When the material of the heat transfer structure 6 (body 61) is metal, specifically when the body is made of stainless steel, a metal having higher thermal conductivity than the material of the heat transfer structure 6 (body 61), e.g., carbon steel, aluminum, or pure copper, can be selected as the material of the heat conductor. It is here to be noted that the substance (material) of the heat conductor preferably has a thermal conductivity as high as possible.

There is known, e.g., a heat exchanger in which the contact surface 63 of the heat transfer structure 6 with the heat exchange target fluid is coated with the fluorine-based resin, and the body 61 is made of stainless steel. For example, in the case of a plate made of stainless steel having a thickness of 8 mm with or without a corrosion-resistant coating of the fluorine-based resin, a total heat transfer coefficient is measured as 1070 W/m²·k for the plate made of only the stainless steel, and 291 for the plate with the corrosion coating of 500 μm. This result shows that an amount of transferred heat is reduced to ⅓ in the latter plate. It is also reported that the heat transfer coefficient is 845 when the plate is coated with the corrosion coating of 50 μm.

Accordingly, the distance between the heat conductor and the heat exchange target fluid is preferably as short as possible.

Embodiment 1 of Heat Exchanger

The structure of a heat exchanger according to Embodiment 1 of the present invention will be described in detail below. A heat exchanger 103 illustrated in FIG. 7 has a parallelepiped shape with dimensions of 150 mm×195 mm×34 mm (height). The heat exchange target fluid is subjected to heat exchange during a process of entering the heat exchanger 103 through an inlet connector (inlet) 81 and passing through the flow passage 7 for the heat exchange target fluid, which includes many bent points (bent portions) 71 and 72, until flowing out from an outlet connector (outlet) 82. The flow passage 7 is provided by forming a groove-like space in a body 61 in the form of a block made of a fluorine-based resin. A number 172 of heat conductors 62 are mounted on both sides of the flow passage 7 at intervals of 600 μm. The heat conductors 62 are each formed of a cross-recessed flat head machine screw (i.e., a screw having a flat head) with a diameter of 3 mm and a length of 18 mm, and they are screwed into holes, which are formed in the body 61 of the heat transfer structure 6, through a heat transfer plate 52a. Because those screws have flat upper surfaces, an upper surface of the heat transfer plate 52a can be made flush. A barrel portion of each screw where threads are formed preferably has a columnar shape that extends in the same diameter without tapering. By employing a standard screw as the heat conductor 62, the manufacturing cost of the heat exchanger can be reduced significantly. The present invention disclosed here involves the case of employing, e.g., a screw (copper) of M3×20 m with a pitch of 0.5 mm or a screw (aluminum) of M4×12 mm with a pitch of 0.7 mm in accordance with JIS standards.

A heat source (not illustrated) is disposed in contact with at least a region of the heat transfer plate 52a where the heat conductors 62 are disposed. The heat source is preferably disposed in contact with respective surfaces of both the heat transfer plates 52a and 52b. The heat source is constituted, for example, as a stainless plate using, as an exothermic source, a nichrome wire with a heater capacity of 1600 W, or a mica plate using, as an exothermic source, a nickel alloy with a heater capacity of 4000 W. An exposed surface of the heat source is preferably covered with a heat insulating material. More preferably, an outermost layer of the heat exchanger 103 is entirely covered with a heat insulating material.

The heat transfer plate 52b is physically coupled to the heat transfer plate 52a, and heat from the heat source is transferred to the heat conductors 62 and the body 61 through the heat transfer plates 52a and 52b. The structural example of FIG. 7 employs a hollow parallelepiped structure in which the heat transfer plate 52a forms an upper surface, the heat transfer plate 52b forms a lower surface, and a frame couples both the heat transfer plates to each other. The heat transfer plates 52a and 52b (and the frame) may be made of the same material as that of the heat conductors 62, or of a material having a higher thermal conductivity than that of the heat conductors 62.

Because the heat conductors 62 and the flow passage 7 (i.e., the heat exchange target fluid) are positioned close to each other through a spacing of 600 μm therebetween, good thermal transfer is obtained. The flow passage 7 through which the heat exchange target fluid passes has dimensions of 6 mm width, 20 mm depth, and 1795 mm length, and includes many bent points (bent portions) midway. In order to increase the number of bent portions, it is preferable to provide not only bent portions which turn the extending direction of the flow passage by 180 degrees, but also a bent portion that turns the extending direction of the flow passage to be returned. More specifically, in the structural example of FIG. 7, a returning bent portion 72 for turning the extending direction of the flow passage by 90 degrees to be returned toward the inlet side (i.e., toward the side denoted by “IN”) is disposed to constitute two flow passage systems A and B with intent to easily increase the number of bent portions. The number of flow passage systems is not limited to two as in the case of FIG. 7, and may be three or more. The heat exchange target fluid flowing through the flow passage strikes against a flow passage wall at the bent points (bent portions) to generate turbulent streams, thereby increasing the efficiency of heat exchange performed at the flow passage wall (contact surface). Preferably, a plurality of heat conductors is disposed between two flow passages 7 arranged parallel to each other. Here, the expression “two parallel flow passages” implies two flow passages that are arranged in such a positional relationship as denoted by 7 and 7 in FIG. 7. Speaking from another viewpoint, the flow passage 7 is preferably disposed to extend in a meander shape through gaps between the heat conductors 62 that are arranged substantially at equal intervals.

The heat exchange efficiency can be increased by coupling the plural heat exchangers 103, each illustrated in FIG. 7, according to the present invention through connectors 81 and 82. The positions and the number of layers of the mounted heat conductors 62 can be determined on the basis of practical studies on the heat exchange efficiency. In a region where the temperature of the heat exchange target fluid is lower than the specified value, holes for mounting of the heat conductors 62 may be newly formed in a corresponding region of the body 61 such that the heat conductors 62 can be additionally mounted in the relevant region.

FIG. 18 is a side view of a multi-stage heat exchanger that is constituted by stacking the heat exchangers 103 each illustrated in FIG. 7. A multi-stage configuration can be obtained by connecting the inlet connector 81 of the heat exchanger 103 in an upper stage and the outlet connector 82 of the heat exchanger 103 in a lower stage through pipes 83a to 83c. While an example of FIG. 18 illustrates a four-stage configuration, the multi-stage configuration is not limited to the illustrated example, and the number of stages may be set to two or more optional numeral. When the heat exchanger is of the multi-stage configuration as illustrated, the flow passage 7 is heated by not only the heat source positioned on the upper side, but also by the heat source positioned on the lower side in the heat exchangers except for that in the lowermost layer. In other words, in the example of FIG. 18, the heat transfer plate 52b is heated by the heat source (heater plate) positioned on the lower side as well. When constituting the multi-stage configuration, a surface at which two stages are stacked is not covered with a heat insulating material such that the heat source positioned in the lower stage and the heat transfer plate positioned in the upper stage are directly contacted with each other.

Thus, in the heat exchanger according to the present invention, the length of the flow passage can be easily prolonged by employing the multi-stage configuration. Furthermore, the heat exchanger according to the present invention is adaptable for various flow rates ranging from a large to small rates by changing the diameter and the total length of the flow passage without modifying an internal structure to be matched with a flow rate of the heat exchange target fluid.

For example, when heat exchange is performed on condition of a flow rate of 10 L/min in terms of nitrogen gas, the heat exchange performance of 80% or more can be obtained even with the body size being reduced to ½. The case of performing the heat exchange on condition of a flow rate of 50 L/min or more is also adaptable by increasing the body size.

Embodiment 2 of Heat Exchanger

FIG. 19 illustrates a configuration of a temperature-controlled supply apparatus 110 according to Embodiment 2 of the present invention. The temperature-controlled supply apparatus 110 includes a cooling-type heat exchanger 106, a cooling device 111, and pipes 112a, 112b, 113a and 113b.

The cooling-type heat exchanger 106 includes a heat transfer structure 6, and cooler plates 54a and 54b. The heat transfer structure 6 may be the same one as that used in each of the heat exchangers 101 to 104. Flow passages through which a coolant circulates are formed to spread over the entire insides of the cooler plates 54a and 54b. For example, an antifreeze solution or a gaseous coolant is used as the coolant. The coolant cooled by the cooling device 111 is supplied to the cooling-type heat exchanger 106 through the pipe 112a, and absorbs heat while passing through the cooling-type heat exchanger 106. After passing through the pipe 112b, the coolant is returned to the cooling device 111 and then supplied again to the cooling-type heat exchanger 106 through the pipe 112a. A heat exchange target fluid 73 (e.g., pure water) is supplied to the cooling-type heat exchanger 106 through the pipe 113a, and is cooled while passing through the cooling-type heat exchanger 106. Thereafter, the coolant is discharged through the pipe 113b.

Practical examples of the present invention will be described below as Examples. It is to be noted that the following Examples merely represent practical examples, and that the present invention is not restricted by the following Examples.

Example 1

The fact that the present invention can improve the heat exchange efficiency was proved by employing a heat exchanger 12 having the same configuration as that of the heat exchanger 103 illustrated in FIG. 7.

A test was conducted using an apparatus arranged as illustrated in FIG. 8. Air 9 controlled in flow rate by a flow rate controller 10 was supplied to a bubbling device 11, thus causing water to be contained in the air 9. Then, the air 9 was passed through the heat exchanger 12. The heat exchanger 12 was provided with a temperature controller 13 for an electric heating panel, a device 14 for measuring an inner temperature of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and a device 15 for measuring an outlet gas temperature to monitor the heat exchange. Moreover, a temperature distribution in the surface of the body 61 was measured by thermography. FIG. 9 indicates the result measured by thermography. In FIG. 9, a darker region represents a region under higher temperature. It was confirmed that the region under higher temperature was coincident with the mounted region of the heat conductors 62. It was also confirmed that a temperature distribution over the entire heat exchanger was not polarized and was uniform.

Example 2

In Example 2, an outlet temperature was measured by conducting tests over respective wide ranges of setting temperature and flow rate, i.e., 40 to 160° C. and 10 to 50 L/min respectively, by employing the same apparatus as that used in Example 1. FIG. 10 depicts the measurement result. It was confirmed that the heat exchange efficiency was 80% or more over the wide ranges of setting temperature and flow rate. It was also confirmed that the heat exchanger according to the present invention was flexibly adaptable for the wide range of flow rate by employing the same configuration without modifications.

Example 3

In Example 3, the performance of the heat exchanger according to the present invention in which heat transfer with respect to the heat exchange target fluid was performed through resin was compared with the performance of the prior-art heat exchanger in which the heat transfer was performed through stainless steel, by employing the electric heating panel used in Example 1. In the present invention, humidified air was subjected to heat exchange as in Example 1. On the other hand, in the prior-art heat exchanger, dried nitrogen was subjected to heat exchange. FIG. 11 depicts the comparison result. “Metal 30L” represents the measurement result for the heat exchanger using stainless steel, and “Resin 30L” represents the measurement result for the heat exchanger according to the present invention. As seen from FIG. 11, the heat exchanger according to the present invention exhibits, even though the contact portion is made of resin, the performance comparable to that of the prior-art heat exchanger using stainless steel.

Additionally, the tests were conducted on mist of H₂O in the heat exchanger according to the present invention, whereas the tests were conducted on dried nitrogen in the prior-art heat exchanger. Because air containing water mist requires heat corresponding to latent heat of water, it is estimated that the heat exchanger according to the present invention has higher performance than the level depicted in FIG. 11.

INDUSTRIAL APPLICABILITY

The heat exchanger according to the present invention is superior in heat exchange performance, and it is able to prevent not only corrosion of the heat exchanger attributable to the heat exchange target fluid, but also contamination of the heat exchange target fluid caused by the corrosion. The heat exchanger according to the present invention is further able to efficiently execute heating, cooling, and temperature control of corrosive chemicals and high-purity substances through heat exchange without causing corrosion and reducing purility of the high-purity substances. The present invention is useful to heat and cool, e.g., chemicals used in a semiconductor manufacturing process where high-purity substances are treated. The heat exchanger and the heat exchange method according to the present invention can be applied to a wide range of fields as high-efficiency heat exchangers in heating and evaporating apparatuses, cooling and condensing apparatuses, etc., including chemical, pharmaceutical, food, textile, electric power, and nuclear power industries in which purity of products and corrosion resistance are required.

LIST OF REFERENCE SYMBOLS

- 1: resin pipe
- 2: inlet of heating target substance
- 3: outlet of heating target substance
- 4: heat medium
- 5: heat source
- 51: heater plate
- 52: heat transfer plate (heat transfer member)
- 53: heat insulating material
- 54: cooler plate
- 6: heat transfer structure
- 61: body
- 62: heat conductor
- 63: contact surface
- 7: flow passage for heat exchange target fluid
- 71: bent portion of flow passage for heat exchange target fluid
- 72: returning bent portion of flow passage for heat exchange target fluid
- 73: heat exchange target fluid
- 74: gap
- 75: discharge port
- 8: connector
- 81: inlet connector (inlet)
- 82: outlet connector (outlet)
- 83: pipe
- 9: air
- 10: flow rate controller
- 11: device for bubbling air into water
- 12: heat exchanger
- 13: device for controlling and measuring temperature of electric heating panel
- 14: device for measuring inner temperature
- 15: device for measuring outlet gas temperature
- 101 to 104: heat exchangers
- 105: heat exchanger equipped with shower head
- 106: cooling-type heat exchanger
- 110: temperature-controlled supply apparatus
- 111: cooling device
- 112 to 113: pipes

HIGH-EFFICIENCY HEAT EXCHANGER AND HIGH-EFFICIENCY HEAT EXCHANGE METHOD

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