JP2006349234A - Heat exchanger for gas water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce dew condensation due to local low temperature shortening a service life of a heat exchanger, and to provide high heat efficiency and miniaturization. <P>SOLUTION: By providing a bent part 18 or a drawn part 19 in a portion surrounded by a plurality of fin pipes 14 wherein a fin 17 locally becomes a low temperature, a heat transfer distance between the fin pipes 14 is extended in combination, and a heat transfer area is increased. Thereby, cooling is prevented, dew condensation is reduced, and compatibility can be provided between service life elongation, high efficiency maintenance, and miniaturization. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fin shape of a heat exchanger of a gas water heater.

  FIG. 4 shows the configuration of a water heater as a conventional technique. A burner 2 is attached in the housing 1 of the gas water heater. A combustion chamber 3 is provided at the upper part of the burner 2, a heat exchanger 4 is further provided at the upper part thereof, and an exhaust passage 5 is further provided at the upper part thereof. Further, a fuel control valve 6 for adjusting the flow rate of the fuel gas is attached upstream of the burner 2, and a fuel stop valve 7 for stopping the fuel gas is attached further upstream. In addition, an air supply fan 8 for sending air necessary for combustion, a flame detector 9 and a spark plug 10 are attached to the burner 2. These fuel control valve 6, fuel shut-off valve 7, air supply fan 8, flame detection device 9, and spark plug 10 are each electrically connected to the control device 11. Further, as a structure of the water passage, a water amount sensor 13 is connected downstream of the water inlet 12, one is connected to the fin pipe 14 of the heat exchanger, and the other is a shortcut to the heat exchanger. Thus, the bypass pipe 15 is connected to the heat exchanger outlet pipe 16.

  Next, the fin part structure of the heat exchanger of a prior art example is shown to Fig.5 (a) (b) (c). FIG. 5A is a top view showing the fin shape, FIG. 5B is a front view showing the fin shape, and FIG. 5C is a perspective view showing the fin structure of the heat exchanger.

  In the figure, a plurality of fin pipes 14 through which water flows (a total of five A to E in the figure) are arranged in the heat exchanger 4 so as to reciprocate several times while traversing the upper part of the combustion chamber 3. A large number of thin fins 17 are joined. The shape is joined to the fins 17 so that the fin pipes 14 (A to E) penetrate therethrough.

  Here, heat exchange will be described with reference to FIG. When the water amount sensor 13 detects the flow of water, the control device 11 rotates the air supply fan 8 when starting the combustion operation. As a result, air enters the housing and is sucked into the air supply fan 8 and discharged into the burner 2. On the other hand, the fuel is opened by the control device 11 with the fuel shut-off valve 7 and the fuel control valve 6 mixed with a part of the air in the burner 2 and ejected from the burner 2 into the combustion chamber 3. At the same time, the control device 11 sparks the spark plug 10 so that the fuel / air mixture is ignited and burned in the combustion chamber 3. The combusted high-temperature exhaust gas touches the fins 17 and the fin pipes 14 of the heat exchanger 4 to absorb heat, exchanges heat with water flowing through the fin pipes 14, drops in temperature, and is discharged through the exhaust passage 5. Next, the movement of the temperature of the heat exchanger fin will be described with reference to FIG.

The water passing through the fin pipe 14 first flows from B to E in order from the fin pipe A in FIG. 5B, and while flowing, it absorbs heat from the plurality of fins 17 and gradually rises in temperature. Meanwhile, the exhaust gas flowing between the fins takes heat away and lowers the temperature. Further, the temperature distribution of the fin 17 is such that the lower end exposed to the high-temperature exhaust gas has the highest temperature, and the portion of the fin pipe 14 surrounded by A to B or B to C to D or D or E The temperature on the downstream side in the exhaust direction (fin upper end) becomes lower (see, for example, Patent Document 1).
JP-A-8-121868

However, in the flat fin shape of the conventional heat exchanger, the portion surrounded by a plurality of fin pipes is short in the heat transfer distance of each pipe and the temperature tends to decrease, so this portion is included in the exhaust gas. As a result, water vapor is condensed, and nitric acid and the like are generated from the nitrogen oxides and the condensed water in the exhaust gas, which damages the heat exchanger and shortens the service life.

  In addition, in order to avoid the problem, it is necessary to take measures such as providing holes in the fins where the temperature is low, and the fin opening reduces the heat transfer area, reducing the thermal efficiency performance or improving the reduced thermal efficiency. Therefore, it is necessary to increase the number of fins or to increase the area of each fin, and as a result, there is a problem that hinders downsizing of the heat exchanger.

  In addition, as a countermeasure against the above issues, in order to reduce the amount of water flowing to the heat exchanger and raise the temperature of the heat exchanger itself to prevent condensation, a bypass is provided upstream of the heat exchanger, and a part of the water amount is exchanged with heat. There is also a method of performing a shortcut without passing through a vessel, but in that case, since the bypass water channel is separately provided, there is a problem that water tends to boil due to an increase in the number of parts and a high temperature of the heat exchanger.

  Therefore, the present invention aims to reduce the size of the heat exchanger and improve the thermal efficiency of preventing condensation by processing the fin shape.

  In order to solve the above problems, a heat exchanger of a gas water heater according to the present invention includes a plurality of fins arranged in parallel and a fin pipe arranged perpendicularly to the fins and penetrating the fins, Bend in the direction of the fins, bend in the oblique direction of the fins, or apply a drawing process to the part of the fins surrounded by the fin pipes, and transfer between the fin pipes through the fins. The heat path is lengthened.

  According to the above invention, by adding bending or drawing to the fin portion surrounded by the fin pipe, it is possible to ensure a long heat transfer distance between the fin pipes and to reduce condensation by reducing the low temperature portion. be able to.

  The heat exchanger of the gas water heater of the present invention can take a long heat transfer distance by adding bending or drawing processing between fin fin pipes, resulting in simultaneous reduction of endothermic interaction with multiple fin pipes. It becomes possible to do. Thereby, compared with the conventional flat fin, when compared with the same fin pipe interval and the same heat exchanger size, it is possible to improve the thermal efficiency and extend the life.

  A first invention includes a plurality of fins arranged in parallel and a fin pipe arranged so as to be perpendicular to the fins and penetrating the fins, bend the fins in a vertical direction, and connect the fin pipes through the fins. The heat transfer path is made longer, and the fin part between the fin pipes is bent to secure the heat transfer distance, and the heat is absorbed from the plurality of fin pipes to reduce the temperature. Therefore, it is possible to prevent excessive condensation and suppress the dew condensation phenomenon, and to increase the heat transfer area.

  A second invention includes a plurality of fins arranged in parallel and a fin pipe arranged so as to be perpendicular to the fins and penetrating the fins, bend the fins in an oblique direction, and connect the fin pipes through the fins. The heat transfer path is made longer.

A third invention includes a plurality of fins arranged in parallel and a fin pipe arranged so as to be perpendicular to the fins and penetrating the fins. The heat transfer path between the fin pipes is made longer.

  In the second invention, as a means for ensuring a long heat transfer path between the fin pipes, a bending process is applied in an oblique direction of the fins, and in the third invention, a drawing process is performed on a portion surrounded by the fin pipes of the fins. The heat transfer path between the fin pipes is ensured for a long time, and in the same way as in the first invention, the heat is mutually absorbed from the plurality of fin pipes to prevent the temperature from being excessively lowered and the dew condensation phenomenon is suppressed. In addition, since the heat transfer area is increased, the effect of improving the thermal efficiency can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the present embodiment.

(Embodiment 1)
About the main body structure of a water heater, and the mechanism of combustion, since it is the same as the example as described in the above-mentioned background art section, explanation is omitted.

  1 (a), (b), and (c) are views showing a fin portion structure of a heat exchanger according to Embodiment 1 of the present invention, FIG. 1 (a) is a top view showing a fin shape, and FIG. FIG. 1B is a front view showing the fin shape, and FIG. 1C is a perspective view showing the fin structure of the heat exchanger.

  In the figure, a plurality of orthogonal fin pipes 14 pass through the fins 17, and a bending process which is a characteristic configuration in the present embodiment is performed on a portion surrounded by the fin pipes 14 to form a bent portion 18. Has been. This bending process may be a corrugated plate bent not only once but also multiple times. According to this shape, if the distance between the fin pipes 14 is the same, the heat transfer distance between the fin pipes 14 can ensure a longer heat transfer distance than the flat fins. By securing this heat transfer distance long, it becomes possible to absorb more heat from the exhaust gas flowing therethrough, and as a result, the temperature of the fins 17 is raised and the dew condensation phenomenon is suppressed. At the same time, the amount of heat transferred to the fin pipe 14 is increased, leading to an increase in thermal efficiency.

(Embodiment 2)
FIGS. 2A, 2B, and 2C are views showing the fin portion structure of the heat exchanger according to Embodiment 2 of the present invention. FIG. 2A is a top view showing the fin shape, and FIG. FIG. 2B is a front view showing the fin shape, and FIG. 2C is a perspective view showing the fin structure of the heat exchanger.

  In the figure, a plurality of orthogonal fin pipes 14 pass through the fins 17, and the portions surrounded by the fin pipes 14 are bent in an oblique direction which is a characteristic configuration in the present embodiment. A bent portion 18 is formed. This oblique bending process may be performed not only once but also in a corrugated shape bent a plurality of times. According to this shape, as in the first embodiment, if the distance between the fin pipes 14 is the same, the heat transfer distance between the fin pipes 14 can ensure a longer heat transfer distance than the flat fins. . The structure that ensures the long heat transfer distance by bending in the oblique direction can absorb more heat from the exhaust gas as compared with the first embodiment, resulting in an increase in the temperature of the fins 17. Therefore, the dew condensation phenomenon can be suppressed, and at the same time, the amount of heat transferred to the fin pipe 14 is increased, leading to an increase in thermal efficiency.

  As described above, in the first and second embodiments, by bending the portion surrounded by the plurality of fin pipes 14, the heat transfer distance between the fin pipes is increased, and the plurality of pipes are mutually connected. It is possible to prevent the temperature from being excessively lowered due to heat absorption, and to improve the thermal efficiency by increasing the heat absorption area.

(Embodiment 3)
FIGS. 3A, 3B, and 3C are views showing the fin portion structure of the heat exchanger according to Embodiment 3 of the present invention. FIG. 3A is a top view showing the fin shape, and FIG. FIG. 3B is a front view showing the fin shape, and FIG. 3C is a perspective view showing the fin structure of the heat exchanger.

  In the figure, a plurality of orthogonal fin pipes 14 pass through the fin 17, and a drawing process which is a characteristic configuration in the present embodiment is performed on a portion surrounded by the fin pipe, and the drawing unit 19 is a fin. It is formed around the pipe. According to this shape, as in the first embodiment, if the distance between the fin pipes 14 is the same, the heat transfer distance between the fin pipes 14 can ensure a longer heat transfer distance than the flat fins. . The structure that secures the heat transfer distance by this drawing process is not limited in the processing position, and can be processed at any place, so that it is possible to obtain a more effective fin shape. It is possible to increase the heat transfer distance between them, suppress the influence of heat absorption from the low-temperature pipe, prevent heat from being mutually absorbed from the plurality of pipes, and prevent the temperature from being excessively lowered, and increase the heat absorption area to improve the thermal efficiency.

  In addition, the bent fins help to disperse stress due to thermal expansion and contraction, and not only chemical degradation due to the formation of condensed water and nitric acid, but also dissipate thermal stress and reduce mechanical breakdown. This makes it possible to extend the service life. Furthermore, if the direction of bending is adjusted to the exhaust direction, the flow of exhaust can be rectified, and there are effects of reducing exhaust resistance, reducing noise, and improving combustion performance.

  The heat exchanger of the present invention can be applied to oil and gas hot water heaters in general because the temperature of the fin pipe and fins in contact with the combustion gas is increased and the occurrence of condensation can be reduced.

(A) (b) (c) The figure which shows the fin part structure of the heat exchanger in Embodiment 1 of this invention (A) (b) (c) The figure which shows the fin part structure of the heat exchanger in Embodiment 2 of this invention (A) (b) (c) The figure which shows the fin part structure of the heat exchanger in Embodiment 3 of this invention Configuration of a conventional water heater (A) (b) (c) The figure which shows the fin part structure of the conventional heat exchanger

Explanation of symbols

14 Fin pipe 17 Fin 18 Fin bending part 19 Fin drawing part

Claims (3)

A plurality of fins arranged in parallel and a fin pipe arranged perpendicularly to the fins and penetrating through the fins, and bending the fins in the vertical direction to lengthen the heat transfer path between the fin pipes through the fins. A gas water heater heat exchanger characterized by A plurality of fins arranged in parallel and a fin pipe arranged perpendicularly to the fins and penetrating the fins, and bending the fins in an oblique direction to lengthen the heat transfer path between the fin pipes through the fins. A gas water heater heat exchanger characterized by A plurality of fins arranged in parallel and a fin pipe arranged so as to be perpendicular to and through the fins, between the fin pipes through the fins by drawing a portion surrounded by the fin pipes of the fins A heat exchanger for a gas water heater characterized by a longer heat transfer path.