JPS629183A - Honeycomb heat exchanger - Google Patents

Abstract

PURPOSE:To reinforce the honeycomb heat exchanger and prevent mixing of fluids surely when cracking occurs by a method wherein a ceramics honeycomb, passing low-temperature fluid, is connected to the outer periphery of the ceramics honeycomb, passing high-temperature fluid, through a ceramics cylindrical body. CONSTITUTION:The honeycomb heat exchanger 1 is made by a method wherein the slurry of powder, consisting of sintered body of silicon carbide having high strength to high temperature and high heat conductivity, is added with binder and is formed into the configuration of honeycomb by extrusion molding. The sectional shape of the honeycomb molded body, thus molded, is circle or fan shape. A block 10 for passing the high-temperature fluid is provided with circular section and the block 20 for passing the low-temperature fluid is provided with segmental section while a ceramics cylindrical body 19, consisting of the sintered body of silicon carbide same as the material of honeycomb forms, is interposed between the blocks 10, 20 to obtain an integral assembled body 2 and install it in a casing 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat exchanger, and more particularly to a honeycomb heat exchanger formed by combining highly thermally conductive ceramic honeycombs.

(Prior Art) Recently, as shown in FIG. 5, a honeycomb heat exchanger that exchanges heat between fluids having a large temperature difference has been developed.
The integrally molded honeycomb molded body 50 is attached to a cylindrical partition wall 51.5.
2, a honeycomb heat exchanger was developed, which is divided into a central part and an outer peripheral part, with a high-temperature fluid passage 53 and a low-temperature fluid passage 54, respectively, and heat exchange is performed through the high-temperature fluid and the low-temperature fluid so that they flow in opposite directions. has been done. Heat is transmitted radially through the honeycomb partition walls 55, 56, and the large electrothermal area allows efficient heat exchange between the fluids even in a stationary state.

(Problems to be Solved by the Invention) However, this newly developed honeycomb heat exchanger generates thermal strain accompanied by tensile stress acting in the circumferential and longitudinal directions during use. Cracks could occur in the longitudinal direction and mixing between the fluids could occur.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems of the conventional technology. The molded bodies are integrated into blocks to be passed through and are combined integrally by a connecting means, and the stress is released by segmentation, and the thermal strain generated in each molded body is also shared by the connecting means to prevent the generation of tensile stress. The purpose is to improve durability. In addition, by interposing a high-temperature, high-strength, and high-thermal-conductivity ceramic cylindrical body between the block that passes high-temperature fluid and the block that passes low-temperature fluid, the honeycomb heat exchanger is reinforced, and cracks are prevented in the unlikely event that cracks occur. It is also possible to reliably prevent mixing between fluids.

(Means for Solving the Problems) The means for achieving the above object is to aggregate a plurality of independent highly thermally conductive ceramic honeycombs into a block through which high temperature fluid passes and a block through which low temperature fluid passes, and to combine the plurality of independent ceramic honeycombs with a connecting means. This is a honeycomb heat exchanger constructed by integrally combining.

(Function) Highly thermally conductive ceramic honeycombs provide a wide heat transfer area with a large number of honeycomb-formed partition walls, and the heat transferred and received by these high thermally conductive ceramic partition walls arranged vertically and horizontally is transferred from the high-temperature block with high efficiency. transferred to the cold block.

Furthermore, the structure formed by combining a plurality of ceramic honeycombs significantly reduces the restraining force against thermal deformation and thermal distortion, and suppresses the generation of especially large tensile stress that causes cracks, compared to the structure formed by integral molding. Connection means such as tightening bands, shrink-fit rings, or shrink-fit sleeves are used to combine and bind a plurality of individually molded ceramic honeycombs as a heat exchanger, and also to restrain the thermal expansion of individual ceramic honeycombs and to Generates compressive stress that is advantageous to prevent cracks from forming.

(Example) Hereinafter, an example of the honeycomb heat exchanger of the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2(b), the honeycomb heat exchanger 1 of this embodiment is made of a powder made essentially of silicon carbide sintered body having high temperature, high strength and high thermal conductivity, and a binder. It is created by extrusion molding a slurry to which is added into a honeycomb shape, and firing the honeycomb shape. Figure 2 (
In the embodiments shown in a) and (b), there are two types of honeycomb molded bodies produced in this way: one with a circular cross section and one with a fan-shaped cross section. A block with a circular cross section is used as a block 10 for passing high-temperature fluid, a fan-shaped block is used as a block 20 for passing low-temperature fluid, and further these blocks 10° 20...
- A ceramic cylindrical body 19 made of a silicon carbide sintered body, which is the same material as these honeycomb molded bodies, is interposed between them, and these are installed in the casing 3 as an integrated assembly 2.

The central honeycomb molded body 10, which constitutes a block through which high-temperature fluid passes, has a cylindrical outer peripheral wall 11 and a plurality of integrally molded parts inside the outer peripheral wall 11 in a lattice shape so as to be orthogonal to each other in the horizontal and vertical directions. Partition walls 12..., 13
...and a large number of passage spaces 14 that penetrate in the longitudinal direction and are formed between these partition walls and between the partition wall and the outer peripheral wall.
It is composed of... The central ceramic honeycomb 1o has a ceramic cylindrical body 19 having high strength and excellent thermal conductivity made of a silicon carbide 1iJ sintered body, which is the same material as the ceramic honeycomb, on its outer periphery.

The outer peripheral ceramic honeycomb 20 constituting the block through which the low-temperature fluid passes has an inner diameter equal to the outer diameter of the ceramic cylindrical body 19, and an outer diameter that is equal to the outer diameter of the central ceramic honeycomb 1, for example.
It has a fan-shaped cross section obtained by equally dividing a ring with a size equivalent to twice 0 into four, and an outer circumferential wall 21 that follows the contour of this sector, and a grid-like cross section inside the outer circumferential wall. A large number of partition walls 22 . The through passage space 24...

The length is shorter than the central ceramic honeycomb 1o.

The coupling means 3o configured integrally with the ceramic honeycomb includes a band 31 made of a steel band bent into a substantially C shape, and a reinforced flange 32 bent outward at right angles at both ends of the band 31. .33 and fasteners 34 such as bolts and nuts, and the band 31
The length is determined to be slightly shorter than the length of the cylindrical outer periphery formed by the four outer peripheral ceramic honeycombs 20, taking into account the interference.

The assembly 2 has a ceramic honeycomb 20 on the outer periphery and a central ceramic honeycomb 10 assembled at both ends in a protruding state. It is fixedly supported within the cylindrical casing 3 via the cylindrical casing 3. The casing 3 forms a low temperature fluid C supply path 5a and its discharge path 5b between it and the assembly 2, and also has a high temperature fluid introduction short pipe 3a and a discharge path having approximately the same diameter as the central ceramic honeycomb 10. Short pipes 3c for use are provided on the front end wall 3b and the rear end wall 3d, respectively, protruding coaxially with the central ceramic honeycomb 10, and the assembly 2 is further connected to the peripheral wall 3.
At e, it is supported in a buffered state by a support 18 made of a heat insulating material. Further, the casing 3 has a short outlet pipe 3f for heating and discharging the low temperature fluid and a short inlet pipe 3g for the low temperature fluid protruding from the front and rear ends of the first circumferential wall 3e, respectively.

The high-temperature fluid H and the low-temperature fluid C form counterflows, respectively.
The former is from the introduction short pipe 3a to the central ceramic honeycomb 1o.
The latter is introduced into the outer peripheral ceramic honeycomb 20 from the inlet short pipe 3g via the supply path 5a, and is introduced into the honeycomb partition walls 12..., 13..., 22..., 23 with high thermal conductivity.
. . . Heat is transferred and received efficiently through the ceramic cylindrical body 19 with good adhesion. The central ceramic honeycomb 10 through which the high-temperature fluid H passes is separated from the outer ceramic honeycomb and has limited thermal expansion to generate compressive stress, and receives heat transfer to the outer ceramic honeycomb 2 whose temperature increases.
Since 0 is also a four-divided body, the tensile stress caused by thermal expansion is released and is small. Rather, the thermal expansion is restrained by the connecting means 30 that binds the outer ceramic honeycomb 20 of the four-divided body, and compressive stress is reduced. The occurrence of cracks is effectively prevented. Even if a crack were to occur partially, the high-temperature, high-strength ceramic cylindrical body 19 would completely prevent fluids from mixing. Although silicon carbide sintered bodies are used for the ceramic honeycomb block 10.20 and the ceramic cylinder 19, other ceramics can also be used as a heat exchanger due to their high strength at high temperatures, high thermal conductivity, and heat resistance. Of course, any applicable material such as silicon nitride can be used. Table 1 below lists and compares the various properties of silicon carbide (SiC) and silicon nitride (S 13N4) that can be used in the present invention with other ceramics (ZrO2.A1□03) and metals.

However, the sample numbers marked with an X are outside the scope of the present invention (-)
The mark is not measured because it is melted or close to melting.As can be understood from Table 1, A1 metal has excellent thermal conductivity, but low high temperature strength and heat resistance, and 5US304 has low thermal conductivity and high temperature strength. It has low heat resistance and cannot be used as a heat exchanger.

In contrast, most ceramics can be used, and silicon carbide sintered bodies (SiC) in particular have excellent thermal conductivity, high-temperature strength, and heat resistance. Zirconia (ZrO2) and A
Although 1□03 is disadvantageous in terms of high temperature strength, it is thought that it can be used if the operating temperature and structure of the heat exchanger are modified.

Regarding the ceramic cylinder 19, the ceramic honeycomb 1
It is preferable that the material is the same as 0.2o, that is, the material has the same coefficient of thermal expansion. They do not need to be made of the same material as long as their thermal expansion coefficients are similar. For example, the coefficient of thermal expansion of a silicon carbide sintered body is 3 to 4 x 10-6/'C, and the coefficient of thermal expansion of a ceramic cylinder that can be used for this is approximately 3 x
A silicon nitride sintered body of 10-'/'C can be used.

<Application example> The honeycomb heat exchanger 1 of the above embodiment is applied to a rapid heating system for a passenger car, etc., as shown in FIG. It is applied to rapidly heat heating air C as a low-temperature fluid that is supplied with combustion gas H as a high-temperature fluid from the air conditioner unit CB and circulated by the air conditioner unit AC.

The combustor CB introduces air sucked in from the air filter AF through the bypass line B under the control of the throttle valve Sv and the spiral valve BV when the starter motor of the engine E is started, and then under the control of the controller CU. The fuel supplied from the tank FT by the combustion pump FP is controlled, vaporized by the carburetor CA, ignited by the spark plug HP, and combusted to generate high-temperature gas.

The high-temperature combustion gas H is supplied to the honeycomb heat exchanger 1 and used as a heat source for heating, and is also used to heat the intake air when starting the engine E, which greatly improves the startability of the engine in the same way as an intake burner. Improve. Therefore,
Diesel cars have the problem of blue-white smoke peculiar to starting,
Odor problems are also eliminated.

As shown in FIG. 4, the rapid heating system incorporating the honeycomb heat exchanger 1 supplied with combustion gas at a high temperature T□ according to the present invention allows heating of light oil of 16 cc/min and air volume of 30 cc/min.
240m'/min at 0Q/min, room temperature 10℃
The amount of air is obtained at approximately 100 degrees Celsius (equivalent to the hot air temperature T2 after heat exchange) around 60 seconds after ignition, making it possible to thaw and defrost the windshield more quickly even at sub-zero temperatures. Ta.

(Effects of the Invention) As described above, according to the honeycomb heat exchanger of the present invention,
Since a plurality of independent highly thermally conductive ceramic honeycombs are aggregated into blocks that allow high-temperature fluid to pass through and blocks that allow low-temperature fluid to pass through, and are integrally combined using a connecting means, it is possible to reduce thermal expansion due to segmentation. Release the tensile stress.

Furthermore, by restraining thermal expansion by the bonding means, it is converted into compressive stress that the ceramic can withstand well, making it possible to effectively prevent the occurrence of cracks, thereby significantly improving durability. In addition, by interposing a high-strength, high-thermal-conductivity ceramic cylindrical body between the block that passes high-temperature fluid and the block that passes low-temperature fluid, it strengthens the honeycomb heat exchanger and improves heat transfer. Even if cracks occur, it is possible to reliably prevent mixing between fluids6.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the honeycomb heat exchanger of the present invention, FIG. 2(a) is a partially sectional perspective view of a ceramic honeycomb combination of the same embodiment, and FIG. 2(b) is a FIG. 3 is a system explanatory diagram showing an application example of a honeycomb heat exchanger, FIG. 4 is a graph showing the performance of the honeycomb heat exchanger of the present invention, and FIG. 5 is a diagram showing a conventional honeycomb heat exchanger. FIG. (Explanation of symbols) 1...Honeycomb heat exchanger of the present invention, 10.20...
Ceramic honeycomb, 19... Ceramic cylindrical body, 3
0...Coupling means. one or more one

Claims (1)

[Scope of Claims] 1. A honeycomb heat exchanger characterized in that a ceramic honeycomb through which a low-temperature fluid passes is integrally joined via a ceramic cylindrical body to the outer circumference of a ceramic honeycomb through which a high-temperature fluid flows. 2. A honeycomb heat exchanger in which the ceramic honeycomb is made of a silicon carbide sintered body. 3. A honeycomb heat exchanger in which the ceramic cylindrical body is made of a silicon carbide sintered body.