JPS582994Y2 - You can't get enough of this. - Google Patents

Description

[Detailed description of the invention] In a conventional heat exchanger for an instantaneous water heater, both heat absorption tubes and heat absorption plates are made of steel pipes and copper plates.

This is because copper is superior in various necessary performances as a heat exchanger for an instantaneous water heater, such as thermal efficiency, after-boiling, flammability limit, and heating speed.

On the other hand, there are some disadvantages as follows.

(1) Condensed water produced during combustion corrodes the surface plating layer on the gas side and subsequently the copper, producing toxic lead sulfate and copper sulfate.

These corrosion products are extremely toxic and may fall or scatter and be released outside the water heater, and may adhere to food, tableware, etc., and may be absorbed by the human body.

(2) A large amount of corrosion products generated on the surface of the heat absorbing plate over time fills the narrow gap between the heat absorbing plates, increasing the passage resistance of the combustion gas, and may even cause a dangerous incomplete combustion state.

(3) When the water heater is stopped, the hot water that stagnates in the heat exchanger dissolves two parts of the copper in the heat absorption tube, and each time the water heater starts to be used, toxic copper ion-containing water (so-called blue water) is generated. If used for consumption, it will be absorbed by the human body.

(4) Copper raw material prices are unstable and fluctuate widely.

In order to solve these drawbacks, the following materials have been considered in place of copper, but they have not been put into practical use because they have even bigger problems.

(1) Aluminum As a general-purpose metal, it has the second highest thermal conductivity after copper, and is low cost.

However, it lacks high-temperature durability and has a low melting point of 660°C, so if it is slightly overheated, it will melt immediately and become useless.

It also has poor corrosion resistance and lacks durability as there is no complete corrosion protection method.

(2) Stainless steel It is corrosion resistant and durable, and its price is relatively low and stable.

However, because the thermal conductivity is very poor (copper's 1.2"24
) With a shape similar to a copper heat exchanger, the necessary performance such as heat exchange rate and after-boiling is significantly inferior, and it is very impractical.

For this reason, various other wire types, such as a heat exchanger in which stainless steel tubes are wound into a coil, have been devised, but they are still inferior in performance, cause frequent drainage, and are almost never put into practical use.

The present invention is to provide a practical heat exchanger for an instant water heater by using stainless steel without using copper and improving the shape of the heat absorption plate.The details are as follows with reference to the attached drawings. .

The stainless steel material is SUS 304 or NAR- for the heat absorption tube.
192 (Japan Stainless Steel product name) is used.

The following two groups of heat absorbing plates are used.

(1) SUS410, 5US405. Martensitic and ferritic stainless steels such as TP409.

Items in this group are not completely corrosion resistant, so the surface is coated with a heat resistant paint.

(2) NAR192, 5US430, 5US304°S
Medium chromium ferritic and austenitic stainless steels such as US 316.

This group has complete corrosion resistance.

However, austenitic stainless steel has somewhat poor thermal conductivity, so performance requirements are stricter.

The basic structure, in which a large number of heat absorption plates are lined up and inserted through a heat absorption pipe, is the same as that of a conventional heat exchanger for instantaneous water heaters, but the shape of the heat absorption plates and the structure of the heat absorption section, which is made up of a group of heat absorption plates, are different. .

Several heat absorbing tubes 1 made of stainless steel thin-walled tubes having the same diameter are arranged in the lower stage at intervals slightly larger than the tube diameters.

In the middle of this lower heat absorption tube 1 made of stainless steel thin-walled tube and above with a gap slightly larger than the pipe diameter, there is a heat absorption tube 2 made of stainless steel thin-walled tube having the same diameter as the aforementioned heat absorption tube 1 made of stainless steel thin-walled tube.
are arranged in a staggered manner.

A large number of heat absorbing plates 3 made of thin stainless steel plates having the shape shown below are attached in parallel to the upper and lower two-stage heat absorbing tubes 1.degree.2 made of thin stainless steel tubes with several wear gaps in the direction orthogonal to the tube axis.

Combustion gas rise prevention portions 6 whose upper portions are inclined inward are formed on both left and right shoulder portions 5 of the three groups of heat absorption plates made of thin stainless steel plates.

A stainless steel U-shaped tube 7 is connected to the ends of the stainless steel thin-walled heat absorption tubes 1 protruding from both front and rear ends of the three groups of stainless steel thin plate heat absorption plates so that all the stainless steel thin-walled tubes 1 communicate in series. It is what it is.

Next, to explain the details of the heat absorption plate made of thin stainless steel plate, the lower side of the heat absorption tube insertion hole 8 bored in the lower stage is formed into a circular arc piece 9 concentric with the heat absorption tube insertion hole 8.

The width of the arcuate pieces 9 is regulated to 6rrrrn or less, and a cutout recess 10 is formed between adjacent arcuate pieces 90 to cut deeply into the upper heat absorption tube insertion hole 8 to about the arcuate width.

The width of this wide circular arc piece 9 is regulated to approximately twice the width of the aforementioned circular arc piece 9, and both left and right shoulder portions are formed into ladder-shaped diagonal lines.

A bent obstructing piece 11 with several body widths is attached to this beveled edge.

The reference numeral 12 in the figure is a fitting circumferential flange.

The heat exchanger of the present invention is installed at the top of the combustion cylinder, which is also made of stainless steel.

The combustion tube consists of an outer case 13 made of thin stainless steel plate, and a stainless steel wound tube 4 whose case wall is cut into a wave shape along the inside of this outer case 13. The heat absorption tube 1 made of thin stainless steel tube of the exchanger is connected to the exchanger.

Since the instantaneous water heater heat exchanger of the present invention is constructed as described above, it exhibits the following features.

1 This product is a heat exchanger in which water is heated to hot water while passing through a number of endothermic tubes in a meandering manner, and since it is made entirely of stainless steel, it has better corrosion resistance (i.e. Excellent corrosion resistance against drain or high temperature corrosion resistance)
Therefore, it is durable with less thinning and deterioration.

In durability tests, it was 4 to 5 times better than copper under the same conditions.

Due to its excellent durability, there are very few corrosion products.

This prevents the scattering of toxic substances, and since there is no need to close the gaps between the tags or the heat absorbing plates, it becomes an excellent product that is unlikely to cause incomplete combustion even if it is worn out.

Since it is made entirely of stainless steel, it has low thermal conductivity, lowers fin efficiency, and the overall temperature of the heat absorbing plate is higher than that of copper.

For this reason, condensate is difficult to form on the heat absorbing plate, and condensate generated in the heat absorbing tube evaporates while traveling through the heat absorbing plate and does not drip onto the burner.

This means that when attempting to increase efficiency, the exhaust gas temperature decreases, resulting in a large amount of condensate, which eventually begins to fall onto the burner, which becomes the limit of efficiency, but this limit can be raised.

2 The heat absorbing tubes are arranged in a staggered manner, but the interval between the lower heat absorbing tubes is larger than the pipe diameter, and the upper heat absorbing tube is placed between them, so that the heat absorbing tubes in the upper stage are also directly above the heat absorbing tubes. This means that the combustion gas is directly exposed to the heat absorption tube, and the heating is improved accordingly.The escape of this combustion gas is also done extremely smoothly because the gap between the upper and lower end of the heat absorption tube is set wider than the pipe diameter, and the heating of the entire heat absorption tube is achieved. It will be done well.

3 Combustion gas rise prevention parts are formed on both left and right shoulders of the heat absorption part, which is formed by arranging a large number of heat absorption plates at intervals of several cylinders, so the rising combustion gas is guided to the center by these rise prevention parts. This means that the combustion gas, which has poor flow on both sides, is brought together in the center and raised intensively, allowing the combustion gas to hit the heat absorption tubes without waste.The heat absorption tubes are arranged in a staggered manner, and since there are fewer of them in the upper stage, they are moved further inside. Inducing the combustion gas toward the heat absorption tube improves the heating of the heat absorption tube.

In addition, by canting both left and right shoulders, the heat storage area is reduced, similar to the arcuate pieces formed on the upper and lower edges, and this heat heats the heat absorption tube, so no heat is wasted, resulting in excellent thermal efficiency.

4. The heat absorption tubes arranged in a staggered manner are connected in series by U-shaped tubes, and the heat absorption plates are also fitted, so the overall assembly is easy.

5 This product is an all-stainless steel heat exchanger, and since stainless steel has poorer thermal conductivity than copper, consideration must be given to the shape of the heat absorbing plate.

In order to deal with the problems of high temperature durability and after-boiling (a phenomenon in which hot water stagnant in the heat absorption tube heated by the heat retained by the heat absorption plate after dissipation flows out for the first time when used after a while), the temperature is 900℃~ ioo.

The lower edge of the heat absorbing plate that first comes into contact with the combustion gas at ℃ is always 4
The temperature must be kept below 50°C.

However, the heat absorption area at the lower edge has the greatest effect on efficiency.

Therefore, the width from the heat absorption tube to the lower edge, which is set to maximize the heat absorption area in the temperature range of 450°C, is 3 to 6 inches wide. Therefore, the heat absorption plate of the present invention has the lower edge concentric with the heat absorption tube insertion hole. It was formed into a circular arc piece, and its width was limited to 6 cylinders or less.

This regulation was set as a result of many experiments, and since the heat absorption plate is originally intended to conduct the added heat to the water in the heat absorption tube, the wider the width of the arc piece, the better. This may be the case, but stainless steel plates do not conduct heat as well as copper plates, so if the width of the arc piece is too wide, the heat received at the outer periphery will not be transferred to the heat absorption tube, causing the periphery to turn red and become overheated. This results in a melting defect.

This is not directly related to the diameter of the heat dissipation tube, but is determined by the thermal conductivity of the stainless steel plate, so even if the type of stainless steel material is different, the thermal conductivity itself does not differ that much, and experimental results show that it is less than 61rrrn. If so, the red heat phenomenon described above would not occur.

This also applies to the lower edge of the heat-absorbing tube located above the middle of the lower-stage heat-absorbing tube, so this condition is satisfied by forming deep notch recesses between the arcuate pieces.

The temperature of the gas passing through the upper edge of the heat absorption plate is 160~2
Since the temperature is as low as 00°C, there is no risk of overheating, so it is formed into a wide arc piece to absorb as much heat as possible, and its width is regulated to about twice that of the lower edge arc piece to ensure a large heat transfer area. I forced him to do so.

However, a shallow notch recess is formed in the middle of the wide arc piece in order to have a negative effect on after-boiling rather than improving efficiency in a portion that is more than twice as far away from the outer periphery of the heat absorption tube.

If the width of this wide arc piece is made larger than 12 cylinders, it will have an adverse effect on after-boiling and at the same time, a large amount of condensate will adhere to the tip.

After-boiling is thought to occur when approximately ÷ of the total amount of heat stored in the heat absorption plates is transferred to the water stagnant in the heat absorption tubes.

The effectiveness of the heat absorbing plate is indicated by the fin efficiency, and the wider the arc width, the worse the fin efficiency becomes.

Furthermore, both corners of the heat absorbing plate, which do not have much effect on efficiency, are canted to produce good results against after-boiling even in S.

In addition, since we attached a blockage piece of several body widths bent at right angles to the cut beveled edge part, when heat absorbing plates are placed side by side, this blockage piece closes both shoulders of the heat absorption part, which prevents the above-mentioned combustion. The formation of the gas rise prevention portion is extremely easy to manufacture.

Thanks to the many features mentioned above, we have created an all-stainless steel instant water heater heat exchanger that has performance that is almost as good as that of steel instant water heater heat exchangers, and which solves the drawbacks of copper. You can get it.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the proposed product, and FIG. 2 is a front sectional view. 1.2... Stainless steel thin-walled heat absorption tube, 3...
... Heat absorption plate made of thin stainless steel plate, 5 ... Both left and right shoulders, 6 ... Rise prevention part, 7 ... U-shaped stainless steel tube, 8 ... ... Endothermic tube insertion hole, 9.
......Circular piece, 10...Notch recess, 11.
...Occlusion piece.

Claims (1)

[Scope of utility model registration request] Several heat-absorbing tubes made of thin-walled stainless steel tubes with the same diameter were placed in the lower tier at intervals slightly larger than the pipe diameters, and in the middle of the heat-absorbing tubes made of thin-walled stainless steel tubes in the lower tier, a gap slightly larger than the tube diameter was placed. Heat absorption tubes made of thin stainless steel tubes having the same diameter as the heat absorption tubes made of thin stainless steel tubes are arranged above in a staggered manner, and heat absorption plates made of thin stainless steel plates are arranged perpendicularly to the tube axis on the heat absorption tubes made of thin stainless steel tubes in two stages, upper and lower. A large number of sheets are attached in parallel with several gaps in the direction, and combustion gas rise prevention parts are formed on both the left and right shoulders of this thin stainless steel heat absorption plate group with the upper part inclined inward, and the heat absorption plate made of thin stainless steel plate is A stainless steel U-shaped tube is connected to the ends of the thin stainless steel heat absorption tubes that protrude from both front and rear ends of the group so that all the stainless steel thin wall heat absorption tubes communicate in series, and the bottom of the stainless steel thin heat absorption plate is The lower side of the drilled heat absorption tube insertion hole is formed into a circular arc piece concentric with the heat absorption tube insertion hole, and the width of this arc piece is restricted to 6 or less, and the upper heat absorption tube is inserted between adjacent circular arc pieces. A notched recess is formed that cuts deeply into the middle of the arc up to the hole, and the upper side of the upper heat absorption tube insertion hole is formed into a wide circular arc piece with a shallow notched recess formed in the middle, and the width of this wide circular arc piece is is restricted to approximately twice the width of the arcuate piece, both left and right shoulders are formed into a ladder-shaped oblique edge, and a block width of a few squares is attached to the oblique edge, which is bent at right angles. Heat exchanger for water heater.