KR20030004024A - Heat exchanger - Google Patents

Abstract

PURPOSE: A heat exchanger is provided to suppress generation of drain and improve heat exchange efficiency. CONSTITUTION: Heat absorbing pipes(5,6,7) are arranged in at least three rows in vertical direction. A heat absorbing accelerating device is placed on a fin(4) under a boundary between the heat absorbing pipes in the second row and the heat absorbing pipes in the third row under the heat absorbing pipe in the first row placed on the top of combustion exhaust to increase heat exchange efficiency. Heat absorbing area of the fin and arrangement of the heat absorbing pipes are set so that ratio of heat exchange efficiency of the parts on the boundary and under the boundary is 97:3-92:8 on maximum combustion of a burner.

Description

Heat exchanger {HEAT EXCHANGER}

The present invention relates to a heat exchanger installed in a hot water heater or the like.

Conventionally, a heat exchanger of this kind installed in a hot water heater has a plurality of fins provided in a combustion exhaust flow path of a burner and a plurality of heat absorbing tubes arranged through the fins, and conducts heat exchange by conducting heated water to the heat absorbing tube. Thus, water is generated.

In general, the endothermic tube has a plurality of first endothermic tube groups arranged in a left and right direction intersecting the combustion exhaust stream, and a left and right direction intersecting the combustion exhaust stream above the first endothermic tube group (downstream of the combustion exhaust stream). A plurality of second heat absorbing tube groups are formed, and the heated water is conducted from the start end of the first heat absorbing tube group toward the end of the second heat absorbing tube group. Further, in order to obtain high heat exchange efficiency, the fin shape is expanded and a third endothermic tube group arranged in a plurality of left and right directions intersecting the combustion exhaust stream is formed above the second endothermic tube group (downstream of the combustion exhaust). Doing. In addition, the start end of the third endothermic tube group is connected to the end of the second endothermic tube group. Therefore, the heat absorbing area is increased, thereby improving heat exchange efficiency.

However, if the heat exchanger forming the third endothermic tube group is constituted, the endothermic area with respect to the combustion amount becomes excessive when the combustion amount of the burner is reduced, so that the exhaust temperature is dew point around the third endothermic tube group. Will be lower. Therefore, water vapor of the combustion exhaust is drained and adhered to the surface of each heat absorbing tube of the third heat absorbing tube group or to a fin near the heat absorbing tube, whereby corrosion occurs in the heat absorbing tube and the fin, thereby reducing the service life.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat exchanger having a simple structure that can suppress drain generation and attain high heat exchange efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically a part of hot water heater which employ | adopted the heat exchanger which concerns on one Embodiment of this invention.

2 is an explanatory diagram showing a main configuration of a heat exchanger according to the present embodiment.

3 is an explanatory perspective view showing the shape of an offset pin;

4 is an explanatory diagram showing a main configuration of a heat exchanger according to another embodiment;

5 is an explanatory diagram showing a main configuration of a heat exchanger according to another embodiment;

6 is a graph showing a drain generating region of a heat exchanger;

7 is an explanatory diagram showing a main configuration of a heat exchanger according to a comparative example;

Explanation of symbols on the main parts of the drawings

A, B, B '-Heat Exchanger 2-Burner

3-combustion exhaust flow path

5,6,7-endothermic tube

16-1st heat absorption pipe group (each heat absorption pipe of the 1st row)

17-2nd heat absorption pipe group (each heat absorption pipe of the second row)

18-third endothermic tube group (each endothermic tube of the third row)

19-first offset pin (endothermic means)

21-2nd offset pin (other offset pin)

26-Slit (endothermic means)

The present invention for achieving the above object is provided with a plurality of fins provided in the combustion exhaust flow path of the burner, and a plurality of endothermic pipes respectively arranged in a vertical direction along the left and right direction and through the combustion exhaust flow to cross the combustion exhaust flow. And a heat exchanger for conducting the heated water from the start end of the endothermic tube located on the upstream side of the combustion exhaust to the end of the endothermic tube located on the downstream side, wherein the endothermic tubes are arranged in at least three rows in the vertical direction. Downstream of each of the heat absorbing tubes of the second row and the heat absorbing tubes of the third row located on the downstream side of each of the heat absorbing tubes located on the upstream side of the combustion exhaust. And an endothermic accelerator for increasing heat exchange efficiency in the fin on the side.

In the present invention, since the endothermic tubes are arranged in at least three rows in the vertical direction, a relatively large endothermic area can be obtained, and high heat exchange efficiency can be obtained.

According to the present invention, first, at the boundary position between each heat absorbing tube of the second row and the heat absorbing tube of the third row located on the downstream side of each heat absorbing tube of the first row located on the most upstream side of the combustion exhaust. The endothermic promoting means is formed to increase the heat exchange efficiency of the fins downstream of this boundary position. Therefore, an extreme drop in the surface temperature of the downstream fins and the heat absorbing tubes can be suppressed, and the surface temperatures of the downstream fins and the heat absorbing tubes can be kept in a relatively high state, thereby preventing the occurrence of drains. have.

In the heat exchanger of the present invention, the heat absorbing area of each of the fins and the heat absorbing pipes are set such that the distribution ratio of the heat exchange efficiency on the upstream side and the downstream side of the boundary position is 97: 3 to 92: 8 at the maximum combustion of the burner. It is preferable that the arrangement of.

As a result of various experiments, the inventors have found that, in a state where a relatively high heat exchange efficiency is obtained throughout the heat exchanger, a heat exchange efficiency in which no drain occurs on the downstream side of the boundary position is required to be 3% to 8% of the total. . Based on this, by setting the heat absorbing area of the fin and the arrangement of the heat absorbing tubes, it is possible to prevent the occurrence of drain and to configure a heat exchanger having high heat exchange efficiency.

Moreover, as one Embodiment of the said endothermic promoting means in this invention, the said endothermic promoting means is comprised by the slit which divides the said fin into the upstream and downstream of a combustion exhaust in the said boundary position. Usually, the position with the highest endothermic rate for this kind of fin is the bottom edge of the fin where the combustion exhaust contacts. This is because the fins of this kind have a property that the thermal conductivity increases at the end edge portion in contact with the combustion exhaust and the temperature thereof is higher than that of the other portions. By forming the slit in the boundary position, an end edge in contact with the combustion exhaust at this boundary position can be formed downstream of the boundary position. Therefore, the heat exchange efficiency on the downstream side is improved, and the surface temperature of the downstream fin and each heat absorbing tube can be increased, so that drainage can be easily prevented in configuration.

In another embodiment of the endothermic accelerator according to the present invention, a pair of parallel notches are formed on a part of the fin at the boundary position, and a plate-shaped portion between both notches is placed in the front and rear directions of the fin. And a plurality of offset pins which are raised to raise the combustion exhaust against the end edge of the notch.

By forming this offset pin, the end edge which a combustion exhaust encounters at the said boundary position is formed in the said notch and the lower edge of each offset pin. Therefore, the heat exchange efficiency on the downstream side can be improved. In addition, by forming a plurality of offset fins, the heat of the combustion exhaust gas can be returned to the upper side of each heat absorbing tube by heat conduction and can be absorbed uniformly. Therefore, the surface temperature of the downstream fin and each heat absorption tube can be raised, and generation | occurrence | production of a drain can be prevented.

In the present invention, a pair of fins located on the downstream side of the combustion exhaust with the endothermic promoting means as a part of the fin at an upper position of each endothermic tube corresponding to the endothermic tube adjacent to the left and right. It is preferable that a plurality of different offset pins are formed, each having a parallel notch of and having raised plate-shaped portions between both notches in the front and rear directions of the pins. According to this other offset fin, the heat of the combustion exhaust which flows between the heat absorbing tubes adjacent to right and left can be returned to the upper side of each heat absorbing tube by heat conduction, and a combustion exhaust heat can be efficiently transmitted to a fin and an endothermic tube efficiently. . Therefore, even if the heat absorbing area of the fin is relatively small, sufficient heat exchange can be performed, and thus the fin can be compactly constructed.

Embodiment of the Invention

EMBODIMENT OF THE INVENTION Embodiment of this invention is described in detail based on drawing.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed a part of hot water heater which employ | adopted the heat exchanger which concerns on this embodiment, FIG. 2 is explanatory drawing which showed the principal structure of the heat exchanger which concerns on this embodiment, and FIG. 3 shows the shape of the offset fin. 4 and 5 are explanatory diagrams showing the main parts of the heat exchanger according to another embodiment, FIG. 6 is a graph showing the drain generating region of the heat exchanger, and FIG. 7 is a main part of the heat exchanger listed as a comparative example. It is explanatory drawing which showed the structure.

As shown in FIG. 1, the heat exchanger A of this embodiment is formed in the combustion exhaust flow path 3 of this burner 2 located above burner 2 of the hot water heater 1. As shown in FIG. The heat exchanger A is composed of a plurality of fins 4 and endothermic tubes 5, 6, 7 which pass through the fins 4, and the water to be heated upstream of the endothermic tubes 5, 6, 7 An introduction pipe 8 for introducing (tap water) is connected, and a discharge pipe 9 for leading heated water (water supply) is connected to the downstream side of the absorption pipes 5, 6, 7. The inlet pipe 8 and the induction pipe 9 are connected by the bypass pipe 10, and the temperature of the hot water of the water intake pipe 9 in the mixing part 11 is adjustable. In addition, the burner 2 controls the combustion amount by the hot water supply operation control means 12. The hot water supply operation control means 12 controls the amount of combustion of the burner 2 based on detection results of a water quantity sensor, a tapping temperature sensor 13 and a water supply temperature sensor 14, which are not shown. In addition, the hot water supply control means 12 is provided with a heat exchange control means 15 (the details thereof will be described later), the burner based on the temperature of the water to be heated in the endothermic pipe (5, 6, 7) Combustion of (2) can be controlled.

As shown in FIG. 2, the heat exchanger A includes a plurality of heat absorbing pipes 5, 6, 7 passing through the fin 4. Each of the heat absorbing tubes 5, 6, and 7 penetrates the fin 4 by meandering a single conduit, and includes the first heat absorbing tube group 16 arranged in the left and right directions on the uppermost side of the combustion exhaust, and the first The second heat absorbing tube group 17 arranged in the left and right directions on the upper side of the heat absorbing tube group 16 and the third heat absorbing tube group 18 arranged in the left and right direction on the upper side of the second heat absorbing tube group 17 are It is arranged in three rows in the vertical direction. The water to be heated is introduced at the beginning of the first endothermic tube group 16 and drawn at the end of the third endothermic tube group 18 as indicated by the arrow in FIG. 2.

A plurality of first offset fins 19 are formed in the fin 4 between the second heat absorbing tube group 17 and the third heat absorbing tube group 18. As shown in Fig. 3, the first offset pin 19 has a pair of parallel notches formed on a part of the pin 4, and then the plate-shaped portion between the two notches is moved from one side to the other. It was formed by raising towards. And the combustion exhaust penetrates the front and back of the said 1st offset pin 19, as shown by the arrow in FIG. As shown in Fig. 2, an auxiliary offset pin 20 is formed at a lower position (upstream side of the combustion exhaust) of the first offset pin 19. As shown in Figs.

Both ends of the first offset pin 19 are formed to have a length located above each of the heat absorbing pipes 6 of the second heat absorbing pipe group 17, thereby constituting the heat absorbing promoting means of the present invention. have. That is, by forming the first offset fin 19, the endothermic region of the fin 4 is divided into the upstream endothermic region 4a and the downstream endothermic region 4b with the imaginary line w shown in FIG. do. As a result, an end edge at which combustion exhaust collides with the bottom edge of the downstream endothermic region 4b can improve heat exchange efficiency. In addition, since the heat of the combustion exhaust gas is returned to the upper side of the heat absorbing tube 6 of the second heat absorbing tube group 17 by the heat conduction by the first offset pin 19, uniform heat transfer is obtained. Heat exchange efficiency can be obtained.

Moreover, the 2nd offset fin 21 and the auxiliary offset fin 22 are formed between each heat absorption tube 7 of the 3rd heat absorption tube group 18. As shown in FIG. These offset fins 21 and 22 improve heat exchange efficiency by causing heat of combustion exhaust gas to return to the upper side of each heat absorbing tube 7 of the third heat absorbing tube group 18 by heat conduction.

Here, the heat exchanger A is provided with a temperature sensor 23 for detecting the temperature of the water to be heated near the inlet of the third heat absorbing tube group 18 as shown in FIG. Then, the third heat absorbing tube is controlled by the heat exchange control means 15 by controlling the combustion amount of the burner 2 corresponding to the flow rate of the water to be heated so that the detected temperature of the temperature sensor 23 is higher than the dew point of the combustion exhaust. Drain generation of each heat absorbing tube 7 of the group 18 and the fin 4 in the vicinity thereof can be reliably prevented.

When this is 88% of the total heat exchange efficiency at the maximum combustion amount of the burner 2, the heat exchange efficiency distribution of the upstream endothermic region 4a and the downstream endothermic region 4b shown in FIG. 2 is shown in Table 1. As described above, the heat exchange efficiency of the upstream endothermic region 4a is 84.6 to 81.5%, and the heat exchange efficiency of the downstream endothermic region 4b is 3.4 to 6.5%.

Water supply temperature (℃) Third endothermic pipe group inlet temperature (℃) Heat exchanger outlet temperature (℃) Heat exchange efficiency of upstream endothermic zone (%) Heat exchange efficiency (%) of downstream endothermic zone 5 55 57 84.6 3.4 20 55 57 83.2 4.8 30 55 57 81.5 6.5

In addition, when the kind of fuel gas of the burner 2 is 13A-1, the air ratio at the time of normal combustion is about 1.6, and the dew point of combustion exhaust at this time is about 51-53 degreeC. In consideration of such dispersion of the air ratio, the heat exchange efficiency of the upstream endothermic region 4a is 85 to 81% and the heat exchange efficiency of the downstream endothermic region 4b is 3 to 7% based on the data in Table 1. It is desirable to. In the present embodiment, the total heat absorbing area of the first offset fins 19 and the fins 4 is set such that the heat exchange efficiency of the upstream end absorbing region 4a and the downstream end absorbing region 4b is distributed. That is, the distribution ratio of the heat exchange efficiency of upstream and downstream is 97: 3-92: 8, and the heat absorption area of the said fin 4 and arrangement | positioning of each heat absorption pipe 7 are set based on this. As a result, a relatively high heat exchange efficiency of 88% of the total heat exchange efficiency at the maximum combustion amount of the burner 2 can be obtained, and drain generation can be prevented and a compact heat exchanger A can be formed.

Moreover, in the said heat exchanger A, instead of the temperature sensor 23 which detects the temperature of the to-be-heated water in the inlet vicinity of the 3rd heat absorption tube group 18, as shown in FIG. A temperature sensor 24 may be provided near the outlet of 18. In this case, the temperature sensor 24 detects the temperature of the heated water (water supply) heated via the heat exchanger (A). The heat exchange control means 15 calculates the temperature of the heated water at the inlet of the third endothermic tube group 18 based on the detected temperature of the temperature sensor 24, the hot water supply capacity, the heat exchange efficiency data, and the like. The combustion amount of the burner 2 corresponding to the flow rate of the water to be heated may be controlled so that the calculated temperature is higher than the dew point of the combustion exhaust. Specifically, the combustion amount of the burner 2 is controlled so that the temperature of the heated heated water (hot water) heated via the heat exchanger A is 57 ° C or higher (see Table 1). By this, drain generation of each heat absorbing tube 7 of the 3rd heat absorbing tube group 18 and the fin 4 in the vicinity can be reliably prevented.

Next, another embodiment of the present invention will be described.

In the heat exchanger B of this embodiment, as shown in FIG. 4, each heat absorbing tube 5, 6, 7 which penetrates the fin 25 is arrange | positioned similarly to FIG. 2, and is the uppermost side of a combustion exhaust. The first heat absorbing tube group 16 arranged in the left and right directions, the second heat absorbing tube group 17 arranged in the left and right directions above the first heat absorbing tube group 16, and the second heat absorbing tube group ( The third endothermic tube group 18 arranged in the left-right direction on the upper side of 17) is arranged in three rows in the vertical direction.

The slit 26 is formed in the fin 25 between the 2nd heat absorption tube group 17 and the 3rd heat absorption tube group 18, and this constitutes the heat absorption promoting means of this invention. That is, by forming this slit 26, the edge which a combustion exhaust contacts can be formed, and the heat exchange efficiency of the lower edge of the downstream endothermic area 25b can be improved. Moreover, in the downstream heat absorption area 25b divided by this slit 26, compared with the above-mentioned 1st offset fin 19 (refer FIG. 2), the upstream heat absorption area 25a and the downstream heat absorption area 25b. The heat transfer of the liver becomes small. Therefore, in order to obtain sufficient heat exchange efficiency, it is necessary to make the heat absorbing area of the downstream heat absorbing area 25b of the fin 25 relatively large. Here, when it is desired to make it more compact, for example, the offset fin 27 between each heat absorbing tube 7 of the 3rd heat absorbing tube group 18 like the heat exchanger B 'shown in FIG. And the auxiliary offset pin 28 can be made compact.

Here, the test which confirms the generation conditions of a drain in the heat exchangers A and B of each above-mentioned embodiment is demonstrated with reference to FIG.

In this test, a heat exchanger C having the configuration shown in FIG. 7 for comparison was used in addition to the heat exchangers A and B. FIG. As shown in Fig. 7, the heat exchanger (C) is arranged in the heat absorbing tube (5, 6, 7) is the same as the heat exchanger (A, B), but the fin 29 is provided with the endothermic promoting means of the present invention. There is no corresponding configuration.

In Fig. 6, when the burner 2 is at the maximum combustion amount, the heat exchange efficiency is maximized because the quantity of the water to be heated in the endothermic pipes 5, 6 and 7 is the maximum and the tapping temperature (heat exchanger outlet water temperature) is minimum. When Solid lines a, b, and c represent drain generating regions (drain lines) of the heat exchanger A (FIG. 2), the heat exchanger B (FIG. 4), and the heat exchanger C (FIG. 7), respectively. . When the drain line is less than or equal to the drain line, a drain is generated in the third heat absorbing tube group 18. In addition, the dashed-dotted lines a ', b', and c 'represent control temperatures of tapping temperatures at which drains do not occur in the third endothermic tube group 18 of the heat exchangers A, B, and C. As can be clearly seen in FIG. 6, the heat exchangers A and B of the above-described embodiments can form the drain line at a lower position than the heat exchanger C of the comparative example. Therefore, according to the heat exchangers A and B of each embodiment, since the tapping temperature can be made relatively low, it is clear that drain generation is prevented and high heat exchange efficiency is obtained.

In addition, although each of the above-described embodiments has shown an example in which three rows of endothermic tubes 5, 6, and 7 are arranged in the vertical direction, they are located at the uppermost part (lowest part of the heat exchanger) even when arranged in three or more rows. It goes without saying that the generation of drain can be reliably prevented by controlling the temperature of the heat exchange group.

As described above, according to the present invention, a heat exchanger capable of suppressing generation of drain and attaining high heat exchange efficiency can be provided with a simple structure.

Claims (5)

A plurality of fins provided in the burner exhaust flow path of the burner, and a heat absorbing tube which is arranged in the left and right directions to cross the combustion exhaust flow through each pin and the vertical direction along the combustion exhaust flow, respectively, and located on the most upstream side of the combustion exhaust In the heat exchanger for conducting the water to be heated from the start end of the heat absorbing tube to the end of the heat absorbing tube located on the most downstream side, The heat absorbing tube is arranged arranged in at least three rows in the vertical direction, On the downstream side of this boundary position, a boundary between each endothermic tube of the second row and the endothermic tube of the third row located on the downstream side of each endothermic tube of the first row located on the upstream side of the combustion exhaust, And an endothermic accelerator for increasing heat exchange efficiency in the fin. The method according to claim 1, The endothermic area of the fin and the arrangement of the endothermic tubes are set so that the distribution ratio of the heat exchange efficiency on the upstream side and the downstream side of the boundary position is 97: 3 to 92: 8 at the maximum combustion of the burner. Heat exchanger made. The method according to claim 1, And the endothermic promoting means is constituted by a slit for dividing the fin into an upstream side and a downstream side of the combustion exhaust at the boundary position. The method according to claim 1, The endothermic facilitating means forms a pair of parallel notches at a portion of the fin at the boundary position, and raises a plate-like portion between both notches in the front and rear direction of the fin so as to strike the combustion exhaust against the end edge of the notch. A heat exchanger, characterized by comprising a plurality of offset fins. The method according to any one of claims 1 to 4, On the fin located downstream of the combustion exhaust with the endothermic promoting means as a boundary, a pair of parallel notches are formed on a part of the fin at an upper position of each endothermic tube corresponding to the left and right adjacent endothermic tubes. And a plurality of different offset fins in which plate portions between the notches are raised in the front and rear directions of the fins.