JP2024075055A - Heat exchanger - Google Patents

Abstract

To provide a heat exchanger for enabling easy maintenance.SOLUTION: A heat exchanger EX includes a tank 1 and a box body 2. The tank has an inflow pipe 17A and an outflow pipe 17B through which primary heat medium W can be put in and out. It also has a lid part 15 via which the box body can be put in and out, and is sealed while storing the plurality of box bodies. Into the box bodies each having no easy-to-bend structure on an outer wall 22, secondary heat medium 5 flows.SELECTED DRAWING: Figure 2

Description

The present invention relates to a heat exchanger.

Conventionally, there have been heat exchangers that use groundwater as a heat source, as described in Patent Document 1. The groundwater pumped up for heat exchange can contain silt (mud) and sand. Furthermore, groundwater can contain impurities such as iron and manganese, and the oxides of these impurities turn into a strong deposit called scale (Non-Patent Document 1). Scale is not very easy to remove. If scale adheres to delicate structures such as heat exchange fins, in the worst case scenario, the only option is to discard the entire heat exchange unit.

Patent No. 7082769

Information from Ube City, JapanWater Purification Forum -Science and Technology- URL: http://water-solutions.jp/commentary/heavy-metals/chromium_manganese_iron/

The objective of this invention is to improve maintainability.

In consideration of these problems, the present invention has solved the problems by providing a heat exchange device that includes a tank and a box body, the tank has an inlet pipe and an outlet pipe, and allows the primary heat medium to be introduced and removed, has a lid that allows the box body to be inserted and removed, is sealed, contains multiple boxes inside, the box body does not have a structure that is easily bent on the outer wall, and allows a secondary heat medium to flow inside.

In one embodiment, the flexible structure is a fin, and the heat exchange device is also disclosed in which the fin is not provided on the outer wall.

In one embodiment, the heat exchange device is disclosed in which the material of the box is a corrosion-resistant material that is at least acid-resistant.

In one embodiment, the heat exchange device is disclosed in which the primary heat medium is a liquid or gas containing contaminants and impurities.

The heat exchange device of the present invention is easy to maintain.

FIG. 1 is an explanatory diagram of an installation using a heat exchanger according to an embodiment of the present invention. Fig. 2 is an explanatory diagram of the heat exchange device. Fig. 2(A) is an explanatory diagram of the tank. Fig. 2(B) is an explanatory diagram of the box body. Fig. 2(C) is an explanatory diagram of the bottom of the tank and the box body. Fig. 3 is an explanatory diagram of a box installed in a tank. Fig. 3(A) is a perspective view showing the state of the box installed in the tank (for the sake of explanation, the box is not shown). Fig. 3(B) is a see-through view of the box. Fig. 3(C) is a cross-sectional view taken along line A-A in Fig. 3(B). FIG. 4 is an explanatory diagram of a modified example in which the boxes are connected in parallel. FIG. 5 shows a modified example of the connecting pipe. 6A and 6B are explanatory diagrams of modified examples. Fig. 6A shows a first modified example of the lid portion 15. Fig. 6B shows a second modified example of the lid portion 15.

The first embodiment of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts with the same function, and duplicate descriptions in each drawing will be omitted as appropriate.

(Example)
FIG. 1 is an explanatory diagram of equipment using a heat exchanger EX according to an embodiment. The primary heat medium W uses groundwater as a hot/cold heat source 9, and is used as a hot heat source in winter and as a cold heat source in summer. Groundwater contains fine particles such as sand and silt as impurities. Groundwater also contains metals and ions such as silica, manganese, iron, and chromium as impurities.

(Primary heat transfer medium)
The heat exchanger EX of the embodiment is effective for a hot or cold heat source containing a large amount of contaminants or impurities. For example, the hot or cold heat source 9 may be a well, seawater, or treated sewage water containing a large amount of contaminants or impurities. The hot or cold heat source 9 of the embodiment is a well, and pumped groundwater is used as the primary heat medium W.
As described later, the heat exchanger EX of the embodiment is not easily affected by contamination by impurities and is easy to clean, so that the primary heat medium W can be made of sewage, industrial wastewater, or even wastewater used to clean an artificial dialysis machine as the hot or cold heat source 9.
It may also be a gas, such as steam or heated air.

(Inlet pipe)
The inlet pipe 17A is a pipe for sending the primary heat medium W from the well (hot/cold heat source 9) to the tank 1. The primary heat medium W, which is groundwater, is pumped up from the well (hot/cold heat source 9) by a pump P and sent to the tank 1 through the inlet pipe 17A.

(tank)
The tank 1 is a main component of the heat exchanger EX of the embodiment. The tank 1 is connected to an inlet pipe 17A, and the inside of the tank 1 is filled with a primary heat medium W sent through a pump P.
A large number of boxes 2 are stored in the tank 1. The inside of the boxes 2 is filled with a secondary heat medium 5. The boxes 2 serve as a heat exchanger that exchanges heat of the primary heat medium W in contact with the outer wall 22 of the boxes 2 with the secondary heat medium 5 inside the boxes 2.
A more detailed description of the tank 1 will be given later.

(Box)
The box body 2 in the embodiment has an external shape of a rectangular parallelepiped, but the shape is arbitrary. Since multiple box bodies 2 are stored in the tank 1, it is preferable that the shape is easy to store. The multiple box bodies 2 may be different sizes from each other. The number of box bodies 2 stored in the tank 1 may be two or more, but it is preferable to have a larger number of box bodies 2 because the heat exchange efficiency increases as the number increases. The box bodies 2 in the embodiment are connected in series by a connecting pipe 21, and the secondary heat medium 5 inside is gradually cooled or heated as it is transported to the adjacent box body 2.
The connection of the boxes 2 by the connecting pipes 21 may be in parallel, as appropriate.
The box 2 will be described in more detail later.

(Box material)
The material of the box 2 is preferably a corrosion-resistant material such as stainless steel that is at least acid-resistant.
The box body 2 is a main component that performs heat exchange and is provided in the heat exchange device EX, and therefore needs to be washed periodically in order to maintain the heat exchange efficiency.
The reason why the material of the box body 2 is required to be corrosion-resistant is that chemicals may be used to clean the box body 2 and remove scale and other deposits.
The tank 1 does not have to be made of a corrosion-resistant material because the heat exchange efficiency is hardly reduced even if scale or other deposits adhere to the inside, but it is preferable that the tank be made of a corrosion-resistant material because chemicals may be used with the box body 2 still inside.

(Hot and cold energy utilization equipment)
The secondary heat medium 5 is transported to the hot and cold heat utilization equipment 4 installed in the room, and the thermal energy stored in the secondary heat medium 5 is used and returned to the tank 1 via the return pipe 5B. The hot and cold heat utilization equipment 4 may be of any type. For example, the hot and cold heat utilization equipment 4 may be a huge structure such as a snow melting device that melts snow accumulated in a parking lot.

(Secondary heat transfer medium)
The secondary heat medium 5 is selected from a medium suitable for carrying heat, such as antifreeze. The secondary heat medium may also be a gas. For example, the air that is the secondary heat medium 5 cooled in the tank 1 is introduced directly into the room and used for cooling. The hot and cold heat utilization equipment 4 is no longer necessary, which reduces costs.

The secondary heat medium 5, which is cooled or heated while passing through the inside of the box 2, is sent to the outside of the box 2 through the delivery pipe 5A and then exits the tank 1. The secondary heat medium 5 is then sent to a hot/cold heat utilization device 4 such as an air conditioner, and is used for indoor heating/cooling and loses its thermal energy. It then passes through the return pipe 5B and returns to the box 2 inside the tank 1.

(Scale buildup)
2A and 2B are explanatory diagrams of the heat exchange device EX. Fig. 2A is an explanatory diagram of the tank 1. Fig. 2B is an explanatory diagram of the box body 2.
The tank 1 of the embodiment contains a plurality of boxes 2 inside. The plurality of boxes 2 are connected to each other by connecting pipes 21 (not shown), and the secondary heat medium 5 that has completed heat exchange in an air conditioner or the like is sent to the boxes 2 through the return pipe 5B. The primary heat medium W sent from the inlet pipe 17A into the tank 1 is heat exchanged with the secondary heat medium 5 inside the boxes 2 while flowing around the boxes 2. The primary heat medium W that has completed heat exchange is discharged from the tank 1 through the outlet pipe 17B and returned to the hot/cold heat source 9 (well).

It is inevitable that the primary heat medium W will contain foreign matter and impurities. In particular, when the primary heat medium W contains many foreign matter and impurities, scale, also known as limescale, will adhere tightly to the outer wall 22 of the box body 2, which is the heat exchanger. For example, calcium contained in groundwater flowing through a calcareous stratum is placed in a high-pressure environment together with carbon dioxide and dissolves in the form of calcium bicarbonate. When the groundwater emerges from underground to above ground, the pressure decreases, and carbon dioxide is released from the groundwater. The dissolved calcium bicarbonate then releases carbon dioxide and precipitates as calcium carbonate, which is less soluble in water. In particular, the heat exchanger is prone to precipitation of dissolved compounds due to the temperature difference between the heat exchanger and the groundwater, and these compounds adhere firmly to the heat exchanger as magnesium silicate or calcium silicate.

Once scale has hardened, it is difficult to remove. For example, scale that has stuck to aluminum heat exchange fins is difficult to remove even by scrubbing with a metal brush. Furthermore, scrubbing the heat exchange fins too hard with a metal brush can cause the fins to bend. The gaps between the heat exchange fins are small, so it is difficult to remove scale that has become stuck between the fins.
As a result, when the scale accumulates too thickly on the heat exchange fins, the heat exchanger must be scrapped.

(Outer wall of the box)
The outer wall 22 of the box body 2 does not have any easily bent structures such as fins, and is configured to make it easy to remove scale. The outer wall 22 does not have any easily bent members such as heat exchange fins, and it is even possible to use a metal brush or a metal spatula.
Furthermore, although aluminum that constitutes the heat exchange fins and the heat exchange body has good thermal conductivity, it is extremely vulnerable to acids, and commercially available acidic scale removers cannot be used.

(Structures that bend easily)
The box body 2 does not prevent a flexible structure that can be easily removed from being attached to the box body 2, because by removing the flexible structure, the box body 2 is free of the flexible structure.
The degree of bendability refers to the degree to which the material is bent by typical cleaning methods used to remove stubborn deposits such as scale.

The box body 2 of the embodiment is made of a corrosion-resistant material and is not corroded by the scale remover. Furthermore, the box body 2 is preferably made of a metal alloy that has good thermal conductivity and is corrosion-resistant. More preferably, the box body 2 is made of a metal alloy that is at least acid-resistant and corrosion-resistant and is not corroded by acidic chemicals such as scale removers. Furthermore, the box body 2 preferably has a hardness that allows the use of a metal brush or a metal spatula. By physical means, the box body 2 of the embodiment is made of a metal alloy that is harder than aluminum, and the outer wall 22 does not have a structure that is easily bent, so that the scale can be removed in a short time by using a physical removal means such as a metal brush.
The box body 2 of the embodiment is thus a component of the heat exchanger EX that places emphasis on ease of maintenance and durability, and is something that has never been seen before.

The hot and cold heat source 9 can be groundwater drawn from a well, or warm treated sewage water immediately after purification, river water, seawater, or other hot and cold heat sources containing foreign matter and impurities. Since the exterior wall 22 of the box body 2 is extremely easy to clean, the heat exchanger EX of the embodiment can use a variety of hot and cold heat sources 9.
Furthermore, even if the groundwater is of a level suitable for drinking, if it is used as the primary heat medium W for a long period of time, scale will accumulate on the heat exchange fins and the water will become unusable. However, the box body 2 of the embodiment can be washed and will not become unusable.

(Internal structure of the tank)
The tank 1 has a lid 15 that opens the top of the tank 1 so that the box bodies 2 can be easily removed. A plurality of box bodies 2 are stored inside the tank 1.
2(C) is an explanatory diagram of the bottom 11 of the tank 1 and the box body 2. A plurality of grooves 111 are provided in the bottom 11 of the tank 1. The grooves 111 have a width that is just suitable for fitting with the box body 2, and the box body 2 is attached to the bottom 11 with a specified gap between them. The box body 2 is fixed simply by fitting into the grooves 111, making it easy to remove and attach.

The box body 2, which has become covered with scale and has reduced heat exchange efficiency, is removed from the tank 1. Then, the scale is removed from the outer wall 22 of the box body 2 using a scale remover or physical means. The tank 1 can easily accommodate the box body 2 again.

The tank 1 does not have any special components inside other than the box body 2. Once the box body 2 is removed, the tank 1 is extremely easy to clean.

(Lid)
The tank 1 and the lid 15 are made of plates including a heat insulating material so that the heat of the primary heat medium W contained in the tank 1 does not escape from the tank 1. The lid 15 is placed on the tank 1 via a sealing material (not shown). The joint between the lid 15 and the tank 1 has an airtight structure that prevents outside air from entering between the lid 15 and the tank 1.

Fig. 3 is an explanatory diagram of the box body 2 installed in the tank 1. Fig. 3(A) is a perspective view showing the state of the box body 2 installed in the tank 1 (for the sake of explanation, the box body 2 is not shown). Fig. 3(B) is a see-through view of the box body 2. Fig. 3(C) is a cross-sectional view taken along line A-A in Fig. 3(B).
The boxes 2 are arranged alternately at intervals so that a flow path through which the primary heat medium W flows is formed between the boxes 2 .
On the other hand, the secondary heat medium 5 supplied to the inside of the box 2 passes through an internal flow path 51 as shown in Fig. 3(B) and Fig. 3(C) to perform efficient heat exchange. Adjacent boxes 2 are connected to each other by a connecting pipe 21. The internal flow path 51 and the connecting pipe 21 allow the secondary heat medium 5 to flow a long distance and receive heat from the primary heat medium W during that time.

[Modification]
(Connecting pipe)
In the embodiment, the connecting pipes 21 are attached so that the internal flow paths 51 of the boxes 2 are connected in series, but they may be attached so as to connect them in parallel.
4 is an explanatory diagram of a modified example in which boxes 2 are connected in parallel. The secondary heat medium 5, whose heat has been used in the hot and cold heat utilization equipment 4, is sent to the tank 1 through a return pipe 5B. Unlike the embodiment, in this modified example, the return pipe 5B and the delivery pipe 5A, which delivers the secondary heat medium 5 that has completed heat exchange, are both guided inside the tank 1. The boxes 2 are connected in parallel by a connecting pipe 21.
The reason why the delivery pipe 5A is turned is so that the return pipe 5B and the delivery pipe 5A are taken out from the same side of the tank 1. If the return pipe 5B and the delivery pipe 5A are on the same side of the tank 1, the piping becomes easier.

(Inlet pipe)
In the heat exchange device EX of the embodiment, one inlet pipe 17A is attached to the tank 1. In a modified example, the primary heat medium W may be supplied to the tank 1 from a plurality of inlet pipes 17A.
To allow for a variety of uses, the tank 1 may have holes on the outer wall 22 to which multiple inlet pipes 17A and outlet pipes 17B can be attached. Any unused holes (not shown) are blocked with insulating plugs. Similarly, multiple delivery pipes 5A and return pipes 5B through which the secondary heat medium 5 passes may also be attached, and corresponding holes are opened in the tank 1 and blocked with plugs.

(Use of seawater)
In the present invention, seawater can be used as the primary heat medium W. After the heat exchange device EX is used for a period of time, the outer wall 22 of the box body 2 becomes covered with marine organisms such as barnacles and shellfish. Since the outer wall 22 does not have any easily bendable structures such as fins that would prevent cleaning, the marine organisms can be easily removed with a metal spatula, a jet of water, or the like.

(Connecting pipe)
5 shows a modified example of the connecting pipe 21. The connecting pipe 21 has a spiral groove on its inner wall. The secondary heat medium 5 exits the connecting pipe 21 into the internal space of the box body 2 while swirling in a spiral shape. The inside of the box body 2 does not have a complicated flow path as in the embodiment. The secondary heat medium 5 exiting the connecting pipe 21 has the effect of stirring the internal space of the box body 2 even without swirling in a spiral shape. Furthermore, the secondary heat medium 5 becomes a water current swirling in a spiral shape, which further stirs the secondary heat medium 5 inside the box body 2.
This action promotes heat exchange between the primary heat medium W and the secondary heat medium 5.
Forming a complex flow path inside the box 2 as in the embodiment is costly, but by taking measures such as those in the modified example, the internal structure of the box 2 can be simplified, thereby reducing costs.

(Spacing between boxes)
The modified example of the spacing between the boxes 2 is an example in which the spacing between the boxes 2 can be changed according to the viscosity of the primary heat medium W.
As mentioned above, the primary heat medium W may be not only a liquid such as groundwater, but also a gas such as steam. Gas has low viscosity (is not sticky), so it can flow even if the spaces between the boxes 2 are close. This allows many boxes 2 to be installed in the same size tank 1, improving the heat exchange efficiency.
On the other hand, liquids, especially liquids such as wastewater that contain a lot of impurities, are highly viscous and difficult to flow. When using a highly viscous liquid that is expected to clog between the boxes 2, this can be addressed by widening the gap between the boxes 2.

(Gap between the lid and the box)
3A , the boxes 2 are staggered and spaced apart to provide flow paths for the primary heat medium W between the boxes 2. The long flow paths arranged in a zigzag pattern increase the contact time between the primary heat medium W and the boxes 2, contributing to improved heat exchange efficiency.
The top surface of the box body 2 in Fig. 2(A) is lower than the top surface of the tank 1, and when the lid 15 is placed on the box body 2, a gap is formed between the box body 2 and the lid 15. However, if such a gap is present, when the water level in the tank 1 rises, the primary heat medium W will not pass through the intended flow path and will overflow the top surface of the box body 2. Furthermore, there is less resistance when the primary heat medium W passes through the gap than when it passes through a zigzag flow path, and the flow of the primary heat medium W overflowing the top surface of the box body 2 becomes the main flow path. This reduces the heat exchange efficiency.

It is preferable that the top surface of the box body 2 be at approximately the same height as the top surface of the tank 1, and that the lid portion 15 abut against the top surface of the box body 2 to eliminate any gap between the lid portion 15 and the box body 2.

(Lid)
6A and 6B are explanatory diagrams of modified examples. Fig. 6A shows a first modified example of the lid part 15. The lower surface of the lid part 15 is provided with a thick part 151. When the lid part 15 is placed on the tank 1, the thick part 151 abuts against the upper surface of the box body 2, eliminating any gap that may occur between the lid part 15 and the box body 2.

Figure 6 (B) shows a second modified example of the lid 15. The underside of the lid 15 is provided with a number of groove-shaped fittings 152, which are designed to fit over the upper part of the box 2.

In addition, the lid 15 has a packing 153 attached around it, the lid 15 is placed over the tank 1, and is airtightly sealed by a crimping member (not shown) so that the packing 153 functions. From the viewpoint of heat exchange efficiency, it is desirable that the box 2 with its upper part swallowed into the fitting part 152 is completely submerged in the primary heat medium W, and the degree of sealing is set to such an extent that the primary heat medium W does not leak from between the lid 15 and the box 2 even when the pressurized primary heat medium W is fed from the inflow pipe 17A.
The effect is more remarkable when a gas such as steam is used as the primary heat medium W. If the lid 15 and the tank 1 are not completely sealed, the gas such as steam will leak out with force. The leakage of the primary heat medium W, which is the heat source, not only reduces the heat exchange efficiency but is also dangerous. In such a modified example, a packing 153 is required.

(Washing)
There are two types of cleaning: simple cleaning and full cleaning. Simple cleaning may be performed by periodically reversing the flow of the inlet pipe 17A and the outlet pipe 17B to clean the inside of the tank 1.
When using a primary heat medium W containing a large amount of impurities, the impurities tend to accumulate at the bottom 11 of the tank 1, so a new cleaning flow path may be provided on the bottom 11 side of the tank 1. As a modified example, a rotary jet nozzle for cleaning may be attached inside the tank 1, and the inside of the tank after the primary heat medium W has been removed may be cleaned.

In this cleaning, the box body 2 is removed from the tank 1, and the tank 1 and box body 2 are cleaned separately. If scale is present, water jet cleaning or cleaning using chemicals is performed. In particular, conventional heat exchangers, which have densely packed heat exchange fins, can bend the fins and become unusable when subjected to water jet cleaning or the like. However, the box body 2 of the embodiment has no parts that are easily deformed and can withstand strong cleaning. The box body 2 can also withstand cleaning methods that physically peel off the scale with a tool such as a spatula.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.
Furthermore, the above-described embodiments can be combined by utilizing each other's technologies, so long as there are no particular contradictions or problems in the purpose, configuration, or the like.

Reference Signs List 1 Tank 11 Bottom 111 Groove 15 Lid 151 Thick wall 152 Fitting 153 Gasket 17A Inlet pipe 17B Outlet pipe 2 Box 21 Connecting pipe 22 Outer wall 4 Hot/cold heat utilization device 5 Secondary heat medium 5A Delivery pipe 5B Return pipe 51 Internal flow path 9 Hot/cold heat source EX Heat exchange device P Pump W Primary heat medium

Claims (4)

Equipped with a tank and a box,
The tank is
It has an inlet pipe and an outlet pipe, and can take in and out the primary heat transfer medium.
The box has a lid that allows the box to be inserted and removed, and is sealed.
A plurality of the boxes are housed inside,
The box body is
There are no easily bent structures on the exterior walls,
A heat exchange device having a secondary heat medium flowing therethrough.
2. The heat exchange device according to claim 1, wherein the flexible structure is a fin, and the fin is not provided on an outer wall.
2. The heat exchanger according to claim 1, wherein the material of the box is at least an acid-resistant and corrosion-resistant material.
The heat exchange device according to claim 1, wherein the primary heat medium is a liquid or gas containing impurities.

Images