JP4728050B2 - Hot water equipment - Google Patents

Description

  The present invention relates to a hot water apparatus such as a water heater provided with two heat exchangers for recovering sensible heat and latent heat from combustion exhaust of a burner and heating water flow.

For example, in a water heater, a main heat exchanger mainly for the purpose of sensible heat recovery is provided upstream of the combustion exhaust passage of the burner, and a sub heat exchanger mainly for the purpose of latent heat recovery is provided on the downstream side. Some are intended to provide high thermal efficiency. The auxiliary heat exchanger is configured such that fins serving as heat absorbing portions are orthogonally arranged at predetermined intervals along the heat transfer tube on the outer periphery of the heat transfer tube through which water passes. In addition, a drain receiving portion that receives drain generated in the auxiliary heat exchanger is provided between the main heat exchanger and the auxiliary heat exchanger, and the generated acidic drain is neutralized and discharged to the outside. (For example, refer to Patent Document 1).
On the other hand, in the heat exchanger, as a double tube structure consisting of an inner tube and an outer tube, a heat transfer facilitator that spirally partitions the inner flow path of the outer tube is provided between the inner tube and the outer tube. A double-pipe heat exchanger is also known (see Patent Document 2).

JP 2004-198065 A JP 2001-201275 A

In the auxiliary heat exchanger, if the combustion exhaust gas is passed through the heat transfer tube in an intersecting manner, the combustion exhaust gas is blocked by the heat transfer tube and does not flow down to the downstream side of the heat transfer tube, resulting in poor heat absorption efficiency. It is desirable to pass the combustion exhaust gas uniformly around the heat transfer tube as a double tube structure as described above.
However, since the drain generated on the surface of the heat transfer tubes and fins stays on the surface of the fins and the inner flow path and inhibits heat exchange with the combustion exhaust, sufficient heat absorption efficiency is achieved even if the combustion exhaust flows along the heat transfer tubes. The improvement was not reached.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hot water device that maintains the advantages of a double tube structure and that can suitably improve the endothermic efficiency without drain retention.

In order to achieve the above-mentioned object, the invention described in claim 1 is characterized in that the fin of the heat transfer tube of the sub heat exchanger is a spiral ridge formed directly on the heat transfer tube, and the fin is included in the sub heat exchanger. A guide tube covering the periphery of the heat transfer tube is provided, a combustion exhaust passage is formed between the guide tube and the heat transfer tube, and the combustion exhaust is passed along the heat transfer tube in the combustion exhaust passage. The heat exchanger is provided with a downward gradient that decreases toward the passage direction of the combustion exhaust gas in the combustion exhaust passage.

According to the first aspect of the present invention, it is possible to improve the heat absorption efficiency by allowing the combustion exhaust gas to pass through the heat transfer tube evenly. In addition, since the drain is quickly discharged by the inclination of the auxiliary heat exchanger, the retained drain does not interfere with the heat absorption, and a suitable heat absorption efficiency can be obtained.
In particular , by using a spiral fin, the heat transfer distance becomes longer and the heat absorption efficiency is improved. Further, the exhaust resistance is reduced by guiding the combustion exhaust in a spiral shape.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a water heater that is an example of a hot water device. The water heater 1 includes a combustion chamber 3 having an air supply fan 4 on the lower side and an exhaust port 5 on the upper side in the appliance body 2. The burner 6 is formed inside the combustion chamber 3 to burn the mixed gas of the fuel gas and the primary air from the air supply fan 4, and the sensible heat in the combustion exhaust from the burner 6 is mainly recovered. A fin tube type main heat exchanger 7 and a fin tube type sub heat exchanger 8 that mainly recovers latent heat are provided internally. Here, the water supply pipe 9 led into the appliance is connected to the water inlet 12 of the auxiliary heat exchanger 8, the auxiliary heat exchanger 8 is arranged upstream of the main heat exchanger 7, and the water discharged from the auxiliary heat exchanger 8 is discharged. The part 13 is connected to the water inlet side of the main heat exchanger 7, and the hot water discharge pipe 10 is connected to the water outlet side of the main heat exchanger 7.

Here, as shown in FIGS. 2 and 3, the auxiliary heat exchanger 8 includes a plurality of (here, four) heat transfer tubes 11 disposed in parallel between the water inlet 12 and the water outlet 13. 11.., A plate-like fin 14 standing in a spiral shape on the outer periphery of each heat transfer tube 11, and a horizontally long guide tube 15 covering all the heat transfer tubes 11 together with the fins 14. In the guide tube 15, partition walls 16, 16... Are partitioned between the heat transfer tubes 11, 11, and the outer peripheral end of the fin 14 is not in contact with the guide tube 15 and the partition wall 16. ing.
Therefore, combustion exhaust passages 17, 17,... For winding the heat transfer tubes 11 in a spiral shape are formed independently in the guide tube 15, respectively. Reference numeral 18 denotes a ridge projecting along the axial direction on the lower surface side of each heat transfer tube 11 in the guide tube 15. The projecting ridge 18 extends below the heat transfer tube 11 in the axial direction outside the fins 14. A communicating groove 19 is formed.

Further, the end of the guide pipe 15 on the side of the water discharge portion 13 becomes an inlet 20 that is not connected to the water discharge portion 13 and opens upward in the combustion chamber 3, and the end of the water intake portion 12 side opens on the upper surface. The outlet 21 is connected to the exhaust port 5. Therefore, all the combustion exhaust gas that has passed through the main heat exchanger 7 enters the guide pipe 15 from the inlet 20, passes through each combustion exhaust passage 17, and is then discharged from the exhaust port 5 through the outlet 21. Become.
And the sub heat exchanger 8 whole is installed in the inclination state so that the inflow part 12 may become lower than the outflow part 13, ie, it may become a downward slope toward the passage direction of combustion exhaust.
Each guide groove 19 of the guide tube 15 is opened downward at the bottom of the water inlet 12, and a receiving tray 22 is provided below the receiving portion 12. The receiving tray 22 has a neutralizer 23. It is connected to the drain discharge pipe 24 provided.

  On the other hand, a main electromagnetic valve 25 and a gas proportional valve 26 are provided in the gas pipe to the burner 6, and a water amount sensor 27 is provided in the water supply pipe 9 and electrically connected to the controller 28. The controller 28 is also electrically connected to a motor for driving the air supply fan 4 and a temperature sensor 29 provided in the hot water discharge pipe 10.

  In the water heater 1 configured as described above, when a hot water tap (not shown) connected downstream of the hot water pipe 10 is opened and water is passed through the appliance, the controller 28 obtains a detection signal from the water amount sensor 27. The main electromagnetic valve 25 and the gas proportional valve 26 are opened to supply gas to the burner 6, and an igniter (not shown) is operated to perform ignition control of the burner 6. After ignition of the burner 6, the controller 28 opens the gas proportional valve 26 according to the difference between the hot water temperature detected by the temperature sensor 29 and the set temperature set by a remote controller (not shown) connected to the controller 28. Is controlled to continuously change the gas amount so that the tapping temperature matches the set temperature. Further, the ratio of the gas amount to the air amount is controlled by changing the rotational speed of the air supply fan 4 in accordance with the change in the gas amount.

  In addition, combustion of the burner 6 causes the combustion exhaust gas to first pass through the main heat exchanger 7, and after sensible heat is recovered by heat exchange with the heat transfer tubes to be passed, The auxiliary heat exchanger 8 enters the guide tube 15 from the inlet 20 of the guide tube 15, passes through the combustion exhaust passages 17, and is discharged from the outlet 21 to the exhaust port 5. Therefore, in the auxiliary heat exchanger 8, sensible heat that has not been recovered by the main heat exchanger 7 is recovered by heat exchange with each heat transfer tube 11 that flows from the water inlet 12 toward the water outlet 13. In particular, due to the spiral combustion exhaust passage 17, the combustion exhaust mainly circulates around the heat transfer tubes 11 and the fins 14 as shown by dotted arrows in FIG. . Furthermore, since the combustion exhaust gas passes between the outer periphery of the fin 14 and the guide tube 15, the combustion exhaust gas can be evenly contacted over the entire fin 14.

  In the auxiliary heat exchanger 8, since the drain is generated when the temperature of the combustion exhaust gas becomes the dew point or lower, the latent heat can also be recovered. The generated drain is collected in the guide groove 19 along the surface of the fin 14, and further flows toward the water inlet 12 side due to the downward gradient of the auxiliary heat exchanger 8, and falls on the receiving tray 22, and is neutralized by the neutralizer 23. Is neutralized and discharged to the sewer outside the appliance. In particular, here, since the wind pressure of the air supply fan 4 is applied to the passage of the combustion exhaust gas, drainage from the guide tube 15 can be performed quickly.

Thus, according to the hot water heater 1 of the said form, the guide pipe 15 which covers the circumference | surroundings of the heat exchanger tube 11 with the fin 14 is provided in the auxiliary heat exchanger 8, and it burns between the guide tube 15 and the heat exchanger tube 11 An exhaust passage 17 is formed to allow combustion exhaust to pass along the heat transfer pipe 11 in the combustion exhaust passage 17, while lowering the auxiliary heat exchanger 8 toward the passage of combustion exhaust in the combustion exhaust passage 17. By providing the downward gradient, it is possible to improve the heat absorption efficiency by allowing the combustion exhaust gas to pass through the heat transfer tube 11 uniformly. In addition, since the drain is quickly discharged by the inclination of the auxiliary heat exchanger 8, the retained drain does not interfere with the heat absorption, and a suitable heat absorption efficiency can be obtained.
In particular, since the fins 14 of the heat transfer tubes 11 of the auxiliary heat exchanger 8 are continuously formed in a spiral shape, the heat transfer distance is increased and the heat absorption efficiency is further improved. Further, the exhaust resistance is reduced by guiding the combustion exhaust in a spiral shape.

  In addition, the shape of the fin in the auxiliary heat exchanger is not limited to the plate shape of the above form, and as shown in FIG. 4, a spiral fin 30 is obtained by directly forming a protrusion on the heat transfer tube 11. May be. In addition, a slight gap is formed between the spiral fin and the guide tube in the above embodiment, but if the exhaust resistance does not increase due to the setting of the pitch of the spiral fin or the like, the outer periphery of the fin is guided. It can also be formed so as to contact the inner surface of the tube. Furthermore, the spiral is not limited to being formed continuously, but can be formed intermittently.

On the other hand, not limited to such a spiral shape, as shown in FIG. 5, a plurality of plate-shaped fins 31, 31... Orthogonal to the heat transfer tube 11 are arranged in parallel in the axial direction of the heat transfer tube 11. It does not matter even if it is a structure. However, in this case, it is necessary to allow passage of combustion exhaust gas and drain so that a gap is formed between the outer peripheral tip of the fin 31 and the inner surface of the guide tube 32. In this modified example, the guide tube 32 also has a bellows shape that matches the position of the fin 31 so that a gap can be formed. However, if the gap between the fins is large, a protrusion corresponding to the fin position may be provided intermittently.
In this way, if the protrusions (including the bellows shape) protruding to the outer peripheral side along the peripheral edge of the fin are provided at the position of each fin in the guide tube in a non-contact manner with the fin, the combustion exhaust is evenly distributed to the entire fin. In addition to being able to make contact, the combustion exhaust gas that passes through the outer periphery of the fin becomes a turbulent flow at the protruding portion, and the contact time with the fin and the heat transfer tube becomes longer, and further improvement in heat absorption efficiency can be expected. In this case as well, as shown in FIG. 6, the bellows-like fins 33 may be formed by the protrusions protruding directly on the heat transfer tube 11.

In addition, the configuration of the guide tube is not limited to the cylindrical shape that covers all the heat transfer tubes together as in the above-described form, and may be configured to be externally provided for each heat transfer tube. In this case, it is necessary to bring the guide tubes into contact with each other or to cover the outside of all the guide tubes with another cylinder so that the combustion exhaust gas is reliably guided to the respective guide tubes.
As for the inclination of the auxiliary heat exchanger, the larger the inclination angle, the faster the drain is discharged, but if the height difference between the inlet and outlet of the combustion exhaust becomes too large, the exhaust resistance will increase. In consideration of balance, it is desirable to set at about 5 to 15 °.

It is a schematic block diagram of a water heater. It is a cross-sectional view of a sub heat exchanger. It is explanatory drawing of the heat exchanger tube part in a subheat exchanger. It is explanatory drawing of the heat exchanger tube part which shows the example of a change of a fin. It is explanatory drawing of the heat exchanger tube part which shows the example of a change of a fin. It is explanatory drawing of the heat exchanger tube part which shows the example of a change of a fin.

Explanation of symbols

1 .... Hot water heater, 2 .... Main body, 3 .... Combustion chamber, 6 .... Burner, 7 .... Main heat exchanger, 8 .... Sub heat exchanger, 9 .... Water supply pipe, 10 .... Hot water pipe , 11 .. Heat transfer pipe, 12 .. Water inlet, 13 .. Water outlet, 14, 31, 33 .. Fin, 15, 32 .. Guide pipe, 17 .. Combustion exhaust passage, 19 .. Guide groove, 20 ..Inlet, 21 ... Exit, 28 ... Controller.

Claims (1)

The main heat exchanger that recovers sensible heat from the combustion exhaust of the burner and heats the water in the heat transfer tube with fins, and the latent heat is recovered from the combustion exhaust that has passed through the main heat exchanger. A hot water device comprising a sub-heat exchanger for heating water flow in a heat transfer tube having fins,
The fin of the heat transfer tube of the auxiliary heat exchanger is a spiral ridge formed directly on the heat transfer tube, and a guide tube that covers the periphery of the heat transfer tube together with the fin is provided in the auxiliary heat exchanger, and the guide A combustion exhaust passage is formed between the pipe and the heat transfer pipe so that the combustion exhaust is allowed to pass along the heat transfer pipe in the combustion exhaust passage, while the auxiliary heat exchanger has a combustion in the combustion exhaust passage. A hot water device characterized by being provided with a downward slope that becomes lower in the exhaust passage direction.

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