JP6413394B2 - Fluid heater - Google Patents

Description

  The present invention relates to a fluid heater that heats a fluid using a resistance heating element.

  Technology that heats fluids such as process fluids and cleaning liquids to a predetermined temperature is not limited to industrial applications such as chemical plants and food factories, but leads to hand dryers installed in commercial facilities and hot water cleaning toilet seats in general households. Widely applied in various fields. In the heating of such a fluid, a method of exchanging heat between a low-temperature side fluid that is a fluid to be heated and a high-temperature side fluid such as steam or a heat medium is often used. When it cannot be used, a heating method using a resistance heating element capable of heating the heated fluid to a desired temperature relatively quickly may be employed.

  For example, in Patent Document 1, a high melting point metal that becomes a resistance heating element is applied to one side of a ceramic sheet by a printing method, and this is wound so that the resistance heating element is on the outer peripheral surface of a ceramic pipe material. A ceramic heater is disclosed that is integrated by bonding and firing after being applied. Patent Document 2 discloses a fluid heating element formed by providing a resistance heating element on the other surface of a flat ceramic substrate whose one surface is a liquid contact surface, and further covering an insulating layer thereon. A ceramic heater is disclosed.

JP 2005-183371 A JP 2002-151236 A

  Due to the recent increase in interest in environmental conservation and power saving, a fluid heater using a resistance heating element is required to have a low power consumption and can efficiently heat a fluid. However, in the structure shown in Patent Document 1 described above, since the material of the sheet covering the resistance heating element is the same as the material of the pipe member around which the sheet is wound, it is generated in the resistance heating element sandwiched between them. Heat could not be efficiently transferred to the fluid flowing inside the pipe-shaped member. Further, in the structure shown in Patent Document 2, cracks are likely to occur at the bonding interface due to a slight difference in thermal expansion coefficient between the ceramic substrate and the insulating layer while the temperature change is repeated, and the reliability may be impaired. In addition, both fluid heaters take time and effort.

  The present invention has been made in view of the problems of the conventional fluid heater, and an object thereof is to provide a fluid heater that has high thermal efficiency, is excellent in reliability, and can be easily manufactured.

  In order to achieve the above object, a fluid heater provided by the present invention includes a lid portion that has a plurality of parallel flow paths inside and seals the plurality of flow paths at one end in the extending direction thereof. A fluid heater having a flow path unit and a heating element accommodated in each of the plurality of flow paths, each of the heating elements accommodated in each of the plurality of flow paths being the lid It is characterized in that at least one reciprocation is made in each flow path from the section.

  ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional fluid heater, the fluid heater which has high thermal efficiency, is excellent in reliability, and can be produced simply can be provided.

It is a longitudinal cross-sectional view which shows one specific example of the fluid heater of this invention. It is a perspective view which shows one specific example of the comb-shaped member by which the heat generating body which the fluid heater of this invention has is wound. It is a perspective view which shows the plate-shaped member which comprises the comb-tooth shaped member of FIG. It is a perspective view which shows the four comb-tooth shaped members produced in the Example with the cover part to which they are attached.

  First, embodiments of the present invention will be listed and described. A fluid heater according to an embodiment of the present invention includes a flow path unit including a plurality of parallel flow paths therein and a lid that seals the plurality of flow paths at one end in the extending direction thereof, A fluid heater having a heating element housed in each of the plurality of flow paths, each of the heating elements housed in each of the plurality of flow paths from the lid portion to the inside of each flow path Is at least one round trip. With this configuration, it is possible to provide a fluid heater that has higher thermal efficiency than the conventional fluid heater, is excellent in reliability, and can be easily manufactured. Further, the manufacture of the flow path unit is facilitated, and maintenance such as replacement of the heating element and cleaning of the inner wall surface of the flow path is facilitated.

  In the fluid heater according to the embodiment of the present invention described above, the flow path unit further includes a plurality of long support members that respectively support the heating elements in the plurality of flow paths. It is preferable that one end of each of the scale support members is engaged with the lid. Thereby, it can prevent that a heat generating body deform | transforms during use, and it can prevent that a heat generating body contacts the wall surface of a flow path and becomes a superheated state locally.

  In the fluid heater according to the above-described embodiment of the present invention, the heating element has a linear shape, and is wound spirally around the elongated support member in each of the plurality of flow paths. In particular, the long support member is preferably formed of a comb-like member. Thereby, it becomes possible to accommodate the heating element at a higher density in the flow path. In the fluid heater according to the above-described embodiment of the present invention, it is preferable that the heating element is covered with an electrical insulating material. Thereby, it is possible to prevent the heating element from being short-circuited and to protect the heating element from the fluid to be heated.

  Next, a specific example of the fluid heater of the present invention will be described with reference to FIG. The fluid heater 1 according to an embodiment of the present invention shown in FIG. 1 has two flow paths extending in parallel to each other and seals the plurality of flow paths at one end in the extending direction. And a linear heating element 20 accommodated in each of the two flow paths. More specifically, the substantially rectangular parallelepiped channel unit 10 includes a channel block 10a having an outward path 11a and a return path 11b extending in parallel to each other, and a seal block for the forward path 11a and the return path 11b. It consists of the 1st cover part 10b and the 2nd cover part 10c which were each provided in the both ends of the extending direction. Here, the term “parallel” includes not only parallel in a strict sense but also a case where the axes of the respective channels are oriented in substantially the same direction. For example, the case where the angle formed by the axes of two flow paths is less than 30 degrees is referred to as parallel.

  The first lid 10b is provided with a supply port 13 and a discharge port 14 for the fluid to be heated, and the supply port 13 and the discharge port 14 communicate with the forward path 11a and the return path 11b, respectively. On the other hand, the second lid portion 10c is formed with a communication path 11c that allows the forward path 11a and the return path 11b to communicate with each other. Thus, the forward path 11a and the return path 11b extending in parallel with each other form a serial flow path 11 together with the communication path 11c. In each of the forward path 11a and the return path 11b, the forward path heating element 20a and the return path heating element 20b respectively pass through the flow path unit 10 from the same end in the extending direction of the forward path 11a and the return path 11b. One round trip. One end portion of the forward heating element 20a and one end portion of the backward heating element 20b are connected to each other to form one series circuit as a whole. Further, the other end of the forward path heating element 20a and the other end of the return path heating element 20b both extend through the wall surface of the flow path unit 10 and are connected to a power source (not shown). Yes. The forward heating element 20a and the backward heating element 20b may reciprocate two or more times in the flow path. As described above, the heating elements respectively accommodated in the plurality of flow paths are reciprocated at least once from the same end portion of the flow path unit 10, thereby passing through the wall surface of the flow path of the flow path unit 10 among the heating elements. Since the connection part and the terminal part described above can be integrated into one end part of the flow path unit 10, processing becomes easy.

  With the above-described configuration, the fluid to be heated introduced into the flow path unit 10 via the supply port 13 first flows from one end portion of the flow path unit 10 to the other end portion through the forward path 11a, Heat is generated by a forward heating element 20 a housed in the forward path 11. The fluid to be heated that has reached the other end of the flow path unit 10 has its flow direction changed by 180 ° in the communication path 11c, and then passes through the return path 11b from the other end of the flow path unit 10 to the one end. In the meantime, it is heated by the return path heating element 20b housed in the return path 11b. In this way, the fluid to be heated that has returned in one reciprocation in the flow path unit 10 is discharged from the discharge port 14.

  The forward heating element 20a and the backward heating element 20b that reciprocate once in the flow path are supported by a long support member 15 in each flow path. As a result, the forward heating element 20a and the return heating element 20b cannot be freely deformed in each flow path, so that the heating element 20 comes into contact with the flow path wall surface under the influence of the flow of the fluid to be heated, for example. , It is possible to prevent local overheating. One end of the long support member 15 is engaged with the first lid portion 10b, so that the heating element 20 can be easily attached to the flow path block 10a together with the first lid portion 10b and the support member 15. It becomes possible to attach and detach. In addition, it is preferable to engage with the 1st cover part 10b in the state which gave the play so that the elongate support member 15 may move to some extent freely. Thereby, it can avoid that stress concentrates on the said engaging part and it breaks.

  When the linear heating element 20 is supported by the long support member 15 as described above, as shown in FIG. 1, the long support member 15 is wound in a spiral shape, and the direction of the spiral axis flows. It is preferable to accommodate in the flow path so as to substantially match the road direction. At that time, it is preferable that the adjacent windings of the heating element 20 are spirally wound at a pitch that does not contact each other. As a result, the heating element 20 can be accommodated in the flow path with a high density, and almost all the surface of the heating element 20 can be brought into contact with the fluid to be heated, so that extremely high thermal efficiency can be achieved. . Furthermore, the local abnormal overheating which may arise when adjacent windings contact | connect can be prevented.

  As shown in FIG. 1, only the forward side or the reverse side of the heating element 20 may be spirally wound on the long support member 15, but it is preferable that both the forward side and the multiple side are spirally wound. . Thereby, the heat generating body 20 can be accommodated at a higher density in the flow path. When both the forward side and the multiple side are spirally wound, it is preferable that the forward side and the reverse side are coaxially wound so that the spiral winding directions are opposite to each other. For example, when the forward side is clockwise, the backward side is preferably left-handed. By reversing the spiral winding direction in this way, it is possible to cancel the magnetic field generated from each coil, and to suppress the adverse magnetic effect of the heater on the periphery.

  As described above, when the linear heating element 20 is spirally wound and accommodated in the flow path, a comb-like member is used to ensure that adjacent windings do not adhere to each other. Is preferred. For example, the comb-like member 30 of one specific example shown in FIG. 2 has a three-dimensional structure in which four rectangular pieces having substantially the same shape having comb teeth have a radial cross section with the comb-tooth side facing outward. By winding the linear heating element 20 along the comb teeth, it can be spirally wound at a desired pitch. And the extending direction of a spiral axis can be made to correspond with the extending direction of a flow path by inserting the comb-tooth shaped member 30 in a flow path in the state in which the heat generating body 20 was wound.

  The comb-tooth shaped member 30 in FIG. 2 can be produced by combining two substantially identical rectangular plate-like members 31 having comb teeth on both sides as shown in FIG. 3, for example. That is, two rectangular plate-like members having the same shape are prepared, comb teeth are provided on both side surfaces extending in the longitudinal direction, and a notch is formed from one end portion in the longitudinal direction to the central portion in the longitudinal direction. The comb-like member 30 can be formed by fitting the notches into each other. The material of the comb-like member 30 is preferably the same as the material of the flow path unit 10.

  When the heating element 20 in the linear form is spirally wound on both the forward side and the multiple side as described above and reciprocated once in the flow path, the adjacent tooth portions 32 of the comb-like member 30 shown in FIG. It is preferable that the outward heating element is spirally wound around the back side of the gap 33 between them, and the return heating element is spirally wound outside the gap 33. At that time, the outward heating element and the returning heating element are separated from each tooth portion 32 of the comb-like member 30 so that the outward heating element and the returning heating element do not contact each other, for example, FIG. It is preferable to fit a spacer 34 such as an annular member. Moreover, it is preferable that the front-end | tip part of each tooth | gear part 32 of the comb-tooth shaped member 30 protrudes outside rather than the outermost periphery part of the spiral of a return side heat generating body. Thereby, it can prevent that the heat generating body 20 contacts the wall surface of the flow-path unit 10, and becomes a superheated state locally.

  The flow path unit having the flow paths as described above is provided with, for example, a solid cylinder or prism block having a plurality of flow paths penetrating in the axial direction, and at least an opening for a supply port and a discharge port. It can be manufactured by sealing both ends with a disc-shaped or rectangular plate-shaped lid provided on one side. The communication path described above may be provided in the lid portion, or may be formed by partially cutting off the end of the flow path provided in the solid cylinder or prism block. When forming the flow path, the processing roughness of the inner wall surface may be made rough to make the fluid flowing inside easily turbulent, or a baffle plate may be provided to lengthen the flow path. As a result, the thermal efficiency can be further increased.

  The flow path of the flow path unit is preferably structured such that the fluid to be heated enters from the lower side and exits from the upper side. Specifically, as shown in FIG. 1, when the outgoing path 11a is installed horizontally so as to be positioned below the return path 11b, the supply port 13 is at the bottom of the forward path 11a, and the discharge port 14 is located on the return path 11b. Preferably it is at the top. This allows the fluid to be filled from the bottom to the top during start-up when the fluid to be heated is introduced into the empty channel, and if the fluid to be heated is a liquid, an air pocket is generated in the channel. Can be filled without any trouble. As a result, since all the heating elements can be immersed in the fluid to be heated, extremely high thermal efficiency can be realized.

  Various materials such as metal and resin can be used as the material of the flow path unit 10, and can be appropriately selected depending on the nature of the fluid to be heated, its operating temperature range, the installation environment of the flow path unit 10, and the like. In the case of a metal, for example, copper, aluminum, stainless steel or the like can be used. These metals are versatile and cost-effective, and can be easily manufactured by machining, brazing, welding, and other processing techniques, so depending on the location of the heater and the size and shape of the heater required It becomes possible to design relatively freely. In addition, metals have the advantage that they have a higher heat resistance temperature and superior mechanical strength than resins, and stainless steel is more excellent in environmental resistance.

  On the other hand, in the case of resin, for example, acrylic, fluororesin or the like can be used. These resins are general-purpose and have excellent cost performance, and can be easily produced by machining techniques such as machining and welding. In particular, since the melting point of resin is lower than that of metal, there is an advantage that shape processing such as welding can be easily performed at a relatively low temperature. In addition, the resin has the advantage of being lightweight and excellent in environmental resistance, and in particular, a fluororesin represented by Teflon has extremely high environmental resistance. For this reason, it can be suitably used for applications where there is a weight limit or for which the environmental load is particularly high.

  It is preferable to use a metal wire covered with an electrical insulating material for the linear heating element 20 accommodated in the flow path. As the material of the metal wire, stainless steel, nickel-chromium, an alloy containing chromium, or the like can be used. For example, vinyl, polyethylene, polyimide, silicone, fluororesin, or the like can be used as an electrical insulating material that covers the entire surface of the metal strand with substantially the same thickness. Specific materials can be appropriately selected depending on the type of fluid to be heated and the operating temperature range thereof. When heat resistance and environment resistance are required, it is desirable to use a fluororesin such as Teflon. In other cases, cost advantage can be obtained by using general-purpose vinyl, polyethylene, polyimide, or silicone.

  The flow path unit 10 may be provided with a temperature sensor. In this case, it is preferable to use a resistance temperature detector for the temperature sensor. The resistance temperature detector is formed by, for example, forming a platinum resistance element on the flat surface portion of the insulating ceramic substrate as a temperature measuring element portion by means such as vapor deposition, and adjusting the resistance value to a predetermined value, and then the electrode pad portion. It can be obtained by bonding the lead wires to each other by means such as bonding. The platinum resistor and the electrode pad are preferably covered with an insulating film. With this configuration, the temperature measuring element unit can be reduced in size, and the temperature responsiveness can be improved.

  The resistance temperature detector can be installed on the outer wall surface or inner wall surface of the flow path unit 10, or in the flow path (space) or on the surface of the insulating coating portion of the heating element. The specific installation location is appropriately selected in consideration of the part to be measured and matching with the control device. During installation, the lead wire of the resistance temperature detector is covered with a metal sheath or a resin pipe, passed through the insertion hole provided in the wall surface of the flow path unit 10, and then welded to maintain the sealing performance with the outside. The temperature in the flow path unit 10 can be measured as it is.

  When measuring the fluid temperature inside the flow path unit 10, in order to avoid mechanical damage due to pressure from the heated fluid, and depending on the type of heated fluid, the temperature of the resin pipe is measured in consideration of environmental resistance. It is preferable that the element portion is covered and the tip portion is filled with a resin substantially the same material as the resin pipe and sealed. Also, when measuring the temperature of the heating element, a temperature measuring element is brought into contact with the surface of the electrical insulating material covering the heating element, and then covered with a resin pipe as described above and sealed with the same means. It is preferable to do this.

  When the temperature sensor is installed on the inner and outer wall surfaces of the flow path unit 10, it can be fixed using an adhesive. As the adhesive, an adhesive mainly composed of an organic resin such as silicone or epoxy, or a combination of an inorganic material such as ceramic particles and a binder component can be used. In particular, the adhesive mainly composed of silicone resin has heat resistance that can withstand the temperature range required for fluid heating and elasticity, so it absorbs a slight difference in thermal expansion between the temperature measuring element and peripheral members. This is preferable.

  The fluid heater of the present invention has been described with reference to a specific example. However, the present invention is not limited to such a specific example, and can be implemented in various modes without departing from the gist of the present invention. . That is, the technical scope of the present invention extends to the claims and their equivalents. For example, in the above-described specific example, the flow paths provided in the flow path unit are communicated in series, but the plurality of flow paths may be communicated in parallel. Further, the number of flow paths provided in the flow path unit is not limited, and is appropriately determined depending on the flow rate of the fluid to be heated, the target temperature reached, the space where it can be installed, and the like. For example, in FIG. 4, four long support members 15 in which a linear heating element 20 is spirally wound are provided on a lid portion of a flow path unit having four flow paths. An example is shown.

  A solid rectangular solid block having a width of 50 mm, a height of 50 mm, and a length of 100 mm made of PTFE was prepared, and four through-holes with an inner diameter of 20 mm extending in the longitudinal direction were provided as first to fourth flow paths therein. . As the coated heating element accommodated in these four flow paths, a metal wire made of SUS304 soft wire having an outer diameter of 0.45 mm and a length of about 10 m was prepared by coating PTFE with a thickness of 0.5 mm. .

  The coated linear heating elements were sequentially spirally wound around four PTFE comb-like members 30 as shown in FIG. At that time, in each comb-like member 30, first, a right-handed spiral is wound around the inner side of the comb-like member 30, and then a PTFE annular spacer is fitted to each tooth portion, and the outer side of the comb-like member 30. Wound in a spiral with a left turn. As a result, the outward heating element and the return heating element could be wound coaxially. Moreover, the front-end | tip part of the tooth | gear part of the comb-tooth shaped member 30 was able to protrude from the outer side of the outermost periphery part of a return side heat generating body.

  As shown in FIG. 4, the four comb-like members 30 each wrapped with one coated linear heating element are connected by the one linear heating element. The block was attached to a rectangular first lid that seals one end in the longitudinal direction of the block. Then, the resistance thermometer is brought into contact with the covering portion on the linear heating element, and in this state, a part of the linear heating element in contact with the resistance thermometer is connected with the resistance thermometer by a pipe. The pipe was welded and sealed at the tip of the pipe to prevent liquid from entering the inside.

  The first lid portion was previously provided with grooves for communicating the first and second flow paths and the third and fourth flow paths. On the other hand, the second lid for sealing the other end of the block in the longitudinal direction has a groove for communicating the second and third flow paths, a lowermost portion of the first flow path, and a fourth flow path. Two openings were provided in advance so as to face the top of each of the two. PTFE pipes were attached to these two openings by welding to form a supply port and a discharge port, respectively. Further, the both ends of the one linear heating element and the resistance temperature detector cord are drawn out from the lead wire through hole provided in the second lid in advance, and connected to the power source and the control device, respectively. . These 1st cover parts and 2nd cover parts were each welded to the both ends of the longitudinal direction of the said block, respectively. Thus, a fluid heater was produced.

  The fluid heater thus manufactured is continuously supplied with water whose temperature is controlled at about 22 ° C. as a fluid to be heated at a flow rate of 1.0 L / min. About 2 kW of electric power was applied to the metal wire to raise the temperature of the water. When this state was continued for a long period of time and the temperature on the outlet side was periodically monitored, the outlet temperature was stably maintained at 47 ° C. As described above, the fluid heater has high thermal efficiency and excellent reliability, and can be easily manufactured.

DESCRIPTION OF SYMBOLS 1 Fluid heater 10 Flow path unit 10a Flow path block 10b 1st cover part 10c 2nd cover part 11 Flow path 11a Outbound path 11b Return path 11c Communication path 13 Supply port 14 Outlet 15 Support member 20 Heat generating body 20a Outbound path heating element 20b Heating element for return path 30 Comb-shaped member 31 Plate-shaped member 32 Tooth part 33 Gap 34 Spacer

Claims (4)

A flow path unit having a plurality of parallel flow paths inside and having a lid portion that seals the plurality of flow paths at one end in the extending direction thereof, and each of the plurality of flow paths was accommodated A fluid heater having a linear heating element, wherein the heating element is supported and accommodated by a long support member having a comb-like shape and a cross-shaped cross section in each of the plurality of flow paths, In each case, at least one reciprocation is made in each flow path from the lid portion, and the long support member is located on the back side of the gap between adjacent tooth portions of the comb-like support member. A fluid heater in which the forward side is wound and the return side of the heating element is wound outside the gap .   The fluid heater according to claim 1, wherein one end portion of the elongated support member is engaged with the lid portion.   The fluid heater according to claim 1, wherein the heating element is spirally wound around the long support member in each of the plurality of flow paths. The fluid heater according to any one of claims 1 to 3 , wherein the heating element is coated with an electrical insulating material.

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