JP2005180778A - Water heating appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve thermal efficiency by averaging surface temperatures of a main heat exchanger and suppressing generation of a local drain. <P>SOLUTION: A temperature of the main heat exchanger 8 of a water heater 1 becomes low as on a water inflow side when a flow rate distribution of combustion exhaust gas is even, and surface temperatures of respective parts of the main heat exchanger 8 become even by controlling the flow rate distribution by a drain evaporator 9 so that the combustion exhaust gas flows in more as on the water inflow side. As a result, heat exchange quantity on the water inflow side can be increased without generating the drain in the main heat exchanger 8. Therefore, heat can be exchanged at a maximum by the main heat exchanger 8, tiny sensible heat which can not be recovered by the main heat exchanger 8 is recovered by an auxiliary heat exchanger 10, and the thermal efficiency of the water heater 1 as a whole can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a hot water apparatus such as a water heater provided with a heat exchanger that heats water through combustion heat of a burner.
In the following description, the term “combustion exhaust” does not mean only the combustion gas after passing through the heat exchanger, but also includes the high-temperature combustion gas generated by the burner combustion before the heat exchange. To use.

  In general, a water heater, which is an example of a hot water device, includes a heat exchanger to which a water supply pipe and a hot water discharge pipe are connected, and a burner for heating the heat exchanger, and passes through the heat exchanger with the combustion heat of the burner. It is configured to heat water and supply hot water from a tapping pipe.

  Usually, in such a water heater, a fin tube type heat exchanger is used, and in the heat exchanger, the temperature of the combustion exhaust gas flowing between the fins is not uniform, and the temperature on the water inlet side of the heat exchanger becomes lower and the drain is likely to be generated. . Therefore, heat exchange is limited so that the temperature of the combustion exhaust flowing between the fins on the water inlet side does not fall below the dew point (approximately 50 to 60 ° C.). For this reason, on the outlet side of the heat exchanger, even though heat can be exchanged more without generating drainage, high-temperature exhaust is discharged as it is.

Therefore, a water heater is also known in which another heat exchanger is provided in the exhaust passage downstream of the heat exchanger to improve the thermal efficiency.
For example, in the water heater shown in Patent Document 1, the combustion exhaust passage of the burner includes a main heat exchanger, a sub heat exchanger, and a drain evaporator, and collects sensible heat in the combustion exhaust heat in the main heat exchanger, Drain is generated in the auxiliary heat exchanger to recover latent heat and sensible heat that could not be recovered in the main heat exchanger, and the drain generated in the auxiliary heat exchanger is evaporated in the drain evaporator using the combustion exhaust heat. I am doing so.
According to this water heater, since the same amount of heat as the latent heat recovered by the auxiliary heat exchanger is used for the evaporation of the drain, the latent heat is not recovered as a result, but compared with a normal water heater. However, a high recovery rate can be obtained for sensible heat.
Further, in this water heater, in order to prevent drain from being generated in the main heat exchanger, the fin pitch of the main heat exchanger is adjusted to be wide on the water inlet side, or the fin thickness is reduced toward the water inlet side. The surface temperature of each part of the main heat exchanger is averaged.
JP 2002-39623 A

However, if the fin pitch or fin thickness of the main heat exchanger is adjusted, the heat exchanger of the standard water heater cannot be used as it is, and it must be created as a dedicated heat exchanger. Therefore, productivity is reduced.
In addition, because heat exchange on the water inlet side of the main heat exchanger is restricted, the high-temperature exhaust heat from the burner is not effectively used for water heating, even if the heat from the exhaust that has passed through the main heat exchanger is sub-heat exchanged. Even if it was going to be recovered by the heat exchanger, there was a limit to the heat recovery rate in the auxiliary heat exchanger, and it could not be said that sufficient heat recovery was possible as a total. In other words, since the main heat exchanger does not exchange heat to the maximum extent, no matter how much the secondary heat exchanger recovers, high thermal efficiency cannot be obtained in the end.
Further, the averaging of the surface temperature of the heat exchanger has a problem that it is difficult to make it uniform by adjusting the fins.
The hot water apparatus of the present invention has an object to solve the above problems, average the surface temperature of the main heat exchanger, suppress the generation of local drainage, and improve the thermal efficiency.

The hot water device according to claim 1 of the present invention for solving the above problems is
A burner that burns fuel in the combustion chamber;
A main heat exchanger that recovers sensible heat from the combustion exhaust of the burner and heats water in the main heat transfer tube;
It is provided in a water passage upstream from the main heat exchanger, and recovers latent heat and sensible heat that could not be recovered by the main heat exchanger from the combustion exhaust gas that has passed through the main heat exchanger. An auxiliary heat exchanger for heating the water flow;
In a hot water apparatus comprising an evaporating dish that receives and evaporates drain generated in the auxiliary heat exchanger,
The gist is to average the surface temperature of each part of the main heat exchanger by controlling the flow distribution of the combustion exhaust gas of the burner flowing to the main heat exchanger by the evaporating dish.

The hot water device according to claim 2 for solving the above-mentioned problems is
A burner that burns fuel in the combustion chamber;
A main heat exchanger that recovers sensible heat from the combustion exhaust of the burner and heats water in the main heat transfer tube;
It is provided in a water passage upstream from the main heat exchanger, and recovers latent heat and sensible heat that could not be recovered by the main heat exchanger from the combustion exhaust gas that has passed through the main heat exchanger. In a hot water device equipped with a sub heat exchanger for heating water flow,
The heat transfer tube of the main heat exchanger has a double tube structure consisting of an inner tube and an outer tube, the water sent from the sub heat exchanger is introduced into the inner tube, and the water that has passed through the inner tube is transferred to the The gist is to average the surface temperature of each part of the main heat exchanger by feeding the outer pipe to the outer pipe and flowing water in the direction opposite to the flow direction of the water in the inner pipe.

The hot water device according to claim 1 of the present invention having the above-described configuration heats the water flowing to the heat transfer pipe of the main heat exchanger by the combustion exhaust of the burner, and turns into the auxiliary heat exchanger by the combustion exhaust that has passed through the main heat exchanger. Heat the flowing water. In the auxiliary heat exchanger, heat is exchanged until drain is generated, and this drain is received by the evaporating dish and heated by the combustion exhaust gas to evaporate.
This evaporating dish controls the flow distribution of the burner combustion exhaust gas flowing into the main heat exchanger to make the surface temperature of each part of the main heat exchanger uniform.
In other words, when the flow distribution of combustion exhaust is uniform, the main heat exchanger becomes cooler at the inlet side, but the main heat exchanger controls the flow distribution with an evaporating dish so that more combustion exhaust flows into the inlet side. Make the surface temperature of each part of the exchanger uniform.
As a result, the amount of heat exchange on the incoming water side can be increased without generating drain in the main heat exchanger. Therefore, heat can be exchanged to the maximum with the main heat exchanger, and the sensible heat that could not be recovered with the main heat exchanger is recovered with the auxiliary heat exchanger, improving the overall thermal efficiency of the hot water equipment. be able to.
Further, since the flow rate distribution is controlled using the evaporating dish, it is not necessary to provide a special distribution plate or the like. In addition, it is not necessary to modify the fins of the main heat exchanger, and productivity is not lowered and costs are not increased.

The hot water apparatus according to claim 2 of the present invention having the above-described configuration heats water flowing to the heat transfer pipe of the main heat exchanger by the combustion exhaust of the burner, and turns it into a sub heat exchanger by the combustion exhaust that has passed through the main heat exchanger. Heat the flowing water.
In the main heat exchanger, the heat transfer tube has a double tube structure, and the supplied water first flows to the inner tube and then is sent to the outer tube. In this case, since the water flowing in the outer pipe is in the direction opposite to the direction of water flowing in the inner pipe, the upstream side in the outer pipe is in contact with the downstream side in the inner pipe.
The combustion exhaust of the burner first exchanges heat with the water in the outer pipe, and the amount of heat obtained downstream increases, but the water in the outer pipe also exchanges heat with the water in the inner pipe at the same time. Since water is colder upstream, the water in the outer tube has a uniform temperature in the flow direction.
As a result, the surface temperature of each part of the main heat exchanger is averaged, and heat exchange can be performed using the entire main heat exchanger until just before drainage is generated. Therefore, heat can be exchanged to the maximum with the main heat exchanger, and the sensible heat that could not be recovered with the main heat exchanger is recovered with the auxiliary heat exchanger, improving the overall thermal efficiency of the hot water equipment. be able to. Moreover, since the combustion exhaust gas sent to the auxiliary heat exchanger has a uniform temperature distribution, heat recovery in the auxiliary heat exchanger can also be performed effectively.
Furthermore, since the outer pipe is located downstream from the inner pipe, the water flowing in the outer pipe is hotter than the water flowing in the inner pipe, so the surface temperature of the main heat exchanger becomes higher and the generation of drainage is increased. Can be suppressed.

  In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the hot water apparatus of the present invention will be described below.

  As shown in FIG. 1, the water heater 1 as Embodiment 1 of the present invention is provided with a combustion chamber 3 in an instrument body 2 and an air supply fan 5 connected to a DC motor 4 is attached below the combustion chamber 3. The instrument body 2 is formed with an air supply port 6 for taking outside air as combustion air.

  In the combustion chamber 3, in order from the bottom, a burner 7 that burns a mixed gas of fuel gas and primary air from the air supply fan 5, and a fin tube type that recovers most of the sensible heat of the combustion exhaust from the burner 7. Main heat exchanger 8, drain evaporator 9 that receives and evaporates the drain, and auxiliary heat exchanger that recovers sensible heat that could not be recovered by the main heat exchanger 8 and latent heat that is generated and recovered by drainage. 10 are provided. In the upper part of the combustion chamber 3, an exhaust port 11 for discharging the combustion exhaust after heat exchange by the main heat exchanger 8 and the sub heat exchanger 10 to the outside of the body is formed.

The water pipe provided in the appliance main body 2 includes, in order from the upstream, a water supply pipe 12 to which cold water is supplied, a winding pipe 13 for winding the combustion chamber 3 on the outside, and a sub heat transfer pipe 14 provided as a sub heat exchanger 10. The main heat exchanger 8 is provided with a main heat transfer pipe 15 and a hot water discharge pipe 16 for hot water. Of these water pipes, the auxiliary heat transfer pipe 14 is a pipe (for example, stainless steel pipe) excellent in corrosion resistance, and the other pipes are made of copper.
On the other hand, the main heat transfer tube 15 is provided with a large number of copper main fins 17 that absorb combustion heat at an equal pitch. For this reason, the main heat exchanger 8 has a lower temperature on the incoming water side and a higher temperature on the outgoing water side.
Further, the positional relationship between the main heat exchanger 8 and the sub heat exchanger 10 is such that the water inlet side of the sub heat exchanger 10 is above the water outlet side of the main heat exchanger 8, that is, the high temperature part side of the main heat exchanger 8. Arrange as follows.

As shown in FIGS. 1, 2, and 3, the drain evaporator 9 has long and thin drain receptacles 18 having a U-shaped cross section arranged in three rows in the horizontal direction, and the left and right ends thereof are respectively A cross-section that covers the drain receiving portion 19 that is integrally coupled and the upper portion of the exhaust gap 20 between the drain receiver 18 and the drain receiver 18 to prevent the drain from dropping to the main heat exchanger 8 and the burner 7 below. It consists of a reverse U-shaped drain cover 21. 2 is a cross-sectional view taken along one-dot chain line AA in FIG. Further, the drain receiver 18 is not formed so that the left and right longitudinal sides are parallel to each other, but is formed so that the lateral width thereof becomes narrower as it goes from the left end portion to the right end portion. Therefore, the exhaust gap 20 between the drain receiver 18 and the drain receiver 18 becomes wider from the left end to the right end.
The drain evaporator 9 is provided in a size that covers the entire upper surface of the main heat exchanger 8, and a wider exhaust gap 20 is provided on the main heat exchanger 8 on the water inlet side, that is, the side facing the low temperature side. It arrange | positions so that the narrower exhaust gap 20 may come in the water discharge side of the exchanger 8, ie, a high temperature side.

  The water supply pipe 12 is provided with a water-side control unit 22 including a water flow sensor and a water governor, and the gas pipe 23 to the burner 7 is provided with a main electromagnetic valve 24 and a gas proportional valve 25. Further, the water flow sensor in the water side control unit 22, the main electromagnetic valve 24, the gas proportional valve 25, the DC motor 4 and the like are electrically connected to a burner controller 26 that controls the combustion of the water heater 1.

In the water heater 1 configured as above, water (broken arrow in the figure) flows through the water supply pipe 12 by opening a hot water tap (not shown), and the burner controller 26 is detected by a detection signal from a water flow sensor in the water side control unit 22. Performs the control operation, and the air supply fan 5 starts to rotate by driving the DC motor 4. When the predetermined pre-purge is completed, the main electromagnetic valve 24 and the gas proportional valve 25 of the burner 7 are opened, fuel gas (solid arrow in the figure) is supplied to the burner 7, and the burner 7 is ignited by an igniter (not shown).
When the ignition operation is finished, proportional control is started. If there is a difference between the hot water temperature detected by the main hot water temperature thermistor (not shown) and the set temperature, the burner controller 26 determines that and sends a signal to the gas proportional valve 25. The gas temperature is continuously changed to keep the outlet temperature of the main heat exchanger 8 constant. Further, a signal is sent from the burner controller 26 to the DC motor 4 of the air supply fan 5 according to the change in the gas amount by the gas proportional valve 25, and the rotation speed of the air supply fan 5 is also changed. Are maintained in a predetermined relationship.

In such combustion control, along with the operation of the air supply fan 5, outside air is sucked into the device main body 2 from the air supply port 6 provided in the device main body 2 and introduced into the burner 7 to be used as combustion air for combustion. Is done. In the vicinity of the flame opening of the burner 7, the air-fuel mixture burns to form a flame, and the combustion is completed (complete combustion) while reaching the upstream vicinity of the main heat exchanger 8.
The high-temperature combustion exhaust from the burner 7 exchanges heat with the water flowing through the main fins 17 of the main heat exchanger 8 and flowing through the main heat transfer tubes 15 by the air supply fan 5, whereby the combustion exhaust having a lowered temperature is generated. The drain evaporator 9 is heated and further exchanged with water flowing through the auxiliary heat transfer pipe 14 of the auxiliary heat exchanger 10 and then discharged from the exhaust port 11 to the outside of the appliance. In the drain evaporator 9, the combustion exhaust gas flows between the exhaust gap 20 and the drain cover 21.
At this time, the main heat exchanger 8 recovers only sensible heat without generating drain, while the sub heat exchanger 10 generates drain and sensible heat that cannot be recovered by the main heat exchanger 8. In addition to recovering latent heat.

  The generated drain is received by a drain evaporator 9 provided immediately below the auxiliary heat exchanger 10. The drain that has fallen on the drain cover 21 also travels along the drain cover 21 and falls on the drain receiver 18, and is heated and evaporated by the combustion exhaust. At this time, the same amount of heat as the recovered latent heat is released into the combustion exhaust, but the auxiliary heat exchanger 10 can recover as much sensible heat as possible from the combustion exhaust without limiting the generation of drain. It becomes. The drain cover 21 also serves as a guide for once guiding the combustion exhaust to the drain on the drain receiver 18.

In the drain evaporator 9, the exhaust gap 20 on the water inlet side of the main heat exchanger 8 is wide and the exhaust gap 20 on the water outlet side is narrow, so that a lot of combustion exhaust flows toward the water inlet side. The surface temperature of the main heat exchanger 8 is made uniform. That is, the drain evaporator 9 controls the flow distribution of the combustion exhaust of the burner 7 to the main heat exchanger 8 to make the surface temperature of each part of the main heat exchanger 8 uniform.
That is, when the flow distribution of the combustion exhaust gas is uniform, the main heat exchanger 8 has a lower temperature at the water inlet side, but the flow distribution is controlled by the drain evaporator 9 so that more combustion exhaust gas flows into the water inlet side. Thus, the surface temperature of each part of the main heat exchanger 8 is made uniform.
As a result, the amount of heat exchange on the incoming water side can be increased without generating drain in the main heat exchanger 8. Therefore, by effectively using the main heat exchanger 8 as a whole, the maximum heat exchange can be performed here, and a small amount of sensible heat that could not be recovered by the main heat exchanger 8 is recovered by the auxiliary heat exchanger 10. Thus, the thermal efficiency of the water heater 1 as a whole can be improved.
Further, since the flow rate distribution is controlled using the drain evaporator 9, it is not necessary to provide a special distribution plate or the like. Further, it is not necessary to modify the main fins 17 of the main heat exchanger 8 and the productivity is not lowered and the cost is not increased.

  Furthermore, since the combustion exhaust flows through between the exhaust gap 20 and the drain cover 21, the drain in the drain receiver 18 is heated in direct contact with the combustion exhaust, so that it is evaporated more efficiently.

Although the first embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
For example, in the first embodiment, the flow rate distribution of the combustion exhaust gas is controlled by adjusting the area of the exhaust passage by changing the opening width of the exhaust gap 20 of the drain evaporator 9, but the present invention is not limited to this. As shown in FIG. 5, the exhaust gap is formed by a large number of round holes 27, and the size of the round holes 27 is changed (FIG. 4) or the density distribution of the round holes 27 is changed (FIG. 5). The flow rate distribution of the exhaust may be controlled. That is, the surface temperature of each part of the main heat exchanger 8 may be made uniform by increasing the exhaust passage area toward the water inlet side of the main heat exchanger 8.

Next, the water heater of Example 2 is demonstrated using FIG.6, FIG.7, FIG.8. In addition, a different part from Example 1 is demonstrated, about the overlapping part, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
In the water heater 201 of the second embodiment, the main heat transfer tube 215 of the main heat exchanger 208 has a double tube structure including an inner tube 229 and an outer tube 230. Then, the water sent from the auxiliary heat exchanger 210 is introduced into the inner pipe 229, the water that has passed through the inner pipe 229 is sent to the outer pipe 230, and the outer pipe 230 is opposite to the water flow direction in the inner pipe 229. Run water in the direction. The main heat transfer tube 215 is provided with a large number of copper main fins 217 that absorb combustion heat at an equal pitch.
In the drain evaporator 209, as shown in FIGS. 6, 7, and 8, the drain receiving part 219 is formed by using a drain receiver 218 in which the left and right longitudinal sides are formed in parallel. Accordingly, the exhaust gap 220 becomes equal in the upper region of the main heat exchanger 208, and the flow of the combustion exhaust does not bias. 7 is a cross-sectional view taken along one-dot chain line BB in FIG.

In such a water heater 201, high-temperature combustion exhaust from the burner 7 exchanges heat with water flowing through the main fins 217 of the main heat exchanger 208 and flowing through the main heat transfer pipe 215 by the air supply fan 5. Thus, the exhaust gas whose temperature has decreased is heated by the drain evaporator 209 and further exchanged heat with water flowing through the auxiliary heat transfer pipe 214 of the auxiliary heat exchanger 210 and then discharged from the exhaust port 11 to the outside of the appliance. In the drain evaporator 209, the combustion exhaust gas flows between the exhaust gap 220 and the drain cover 21.
At this time, the main heat exchanger 208 recovers only sensible heat without generating drain, while the sub heat exchanger 210 generates drain and sensible heat that could not be recovered by the main heat exchanger 208. In addition to recovering latent heat. The generated drain is received by a drain evaporator 209 provided immediately below the auxiliary heat exchanger 210, and is heated and evaporated by combustion exhaust gas.
In the main heat exchanger 208, the main heat transfer tube 215 has a double tube structure, and the supplied water first flows to the inner tube 229 and then is sent to the outer tube 230. In this case, since the water flowing through the outer tube 230 is in the opposite direction to the direction of water flowing through the inner tube 229, the upstream side of the outer tube 230 is in contact with the downstream side of the inner tube 229.
The combustion exhaust of the burner 7 first exchanges heat with the water in the outer tube 230, and the amount of heat obtained at the downstream side increases, but the water in the outer tube 230 also exchanges heat with the water in the inner tube 229 at the same time. Since the water in the inner pipe 229 is colder toward the upstream, the temperature in the flow direction of the water in the outer pipe 230 is uniform.
As a result, the surface temperature of each part of the main heat exchanger 208 is averaged, and heat exchange can be performed using the entire main heat exchanger 208 until just before drainage is generated. Therefore, the main heat exchanger 208 can exchange heat to the maximum extent, and the sensible heat that could not be recovered by the main heat exchanger 208 is recovered by the auxiliary heat exchanger 210, so that Thermal efficiency can be improved. Moreover, since the combustion exhaust gas sent to the auxiliary heat exchanger 210 has a uniform temperature distribution, heat recovery in the auxiliary heat exchanger 210 can also be performed effectively.
Furthermore, since the outer pipe 230 is located downstream of the inner pipe 229, the water flowing through the outer pipe 230 is hotter than the water flowing through the inner pipe 229, so the surface temperature of the main heat exchanger 208 is even higher. The generation of drain can be suppressed.
In this embodiment, the generated drain is evaporated, but the present invention is not limited to this. A neutralization device is provided, and after draining is neutralized, the liquid is discharged out of the apparatus as a liquid. It is good also as a simple structure.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
For example, in the present embodiment, an example is shown in which the present invention is applied to a forced combustion type water heater 1,201 provided with an air supply fan 5, but the present invention is not limited to this, and a natural combustion type that does not include an air supply fan. You may apply to a water heater.

  The present invention can be applied to a hot water device that heats water through the combustion heat of a burner and produces hot water.

1 is a schematic configuration diagram of a water heater as Example 1. FIG. It is sectional drawing of the drain evaporator as Example 1. FIG. 1 is a plan view of a drain evaporator as Example 1. FIG. It is a top view of the drain evaporator as another Example. It is a top view of the drain evaporator as another Example. It is a schematic block diagram of the water heater as Example 2. It is sectional drawing of the drain evaporator as Example 2. FIG. It is a top view of the drain evaporator as Example 2. FIG.

Explanation of symbols

1,201 Water heater 3 Combustion chamber 7 Burner 8, 208 Main heat exchanger 9, 209 Drain evaporator 10, 210 Sub heat exchanger 14, 214 Sub heat transfer tube 15, 215 Main heat transfer tube 229 Inside through 230 Outer tube

Claims (2)

A burner that burns fuel in the combustion chamber;
A main heat exchanger that recovers sensible heat from the combustion exhaust of the burner and heats water in the main heat transfer tube;
It is provided in a water passage upstream from the main heat exchanger, and recovers latent heat and sensible heat that could not be recovered by the main heat exchanger from the combustion exhaust gas that has passed through the main heat exchanger. An auxiliary heat exchanger for heating the water flow;
In a hot water apparatus comprising an evaporating dish that receives and evaporates drain generated in the auxiliary heat exchanger,
A hot water apparatus characterized by controlling the flow distribution of combustion exhaust gas of the burner flowing to the main heat exchanger by the evaporating dish and averaging the surface temperature of each part of the main heat exchanger. A burner that burns fuel in the combustion chamber;
A main heat exchanger that recovers sensible heat from the combustion exhaust of the burner and heats water in the main heat transfer tube;
It is provided in a water passage upstream from the main heat exchanger, and recovers latent heat and sensible heat that could not be recovered by the main heat exchanger from the combustion exhaust gas that has passed through the main heat exchanger. In a hot water device equipped with a sub heat exchanger for heating water flow,
The heat transfer tube of the main heat exchanger has a double tube structure consisting of an inner tube and an outer tube, the water sent from the sub heat exchanger is introduced into the inner tube, and the water that has passed through the inner tube is transferred to the A hot water apparatus characterized in that the surface temperature of each part of the main heat exchanger is averaged by feeding water to the outer pipe and flowing water in the outer pipe in a direction opposite to the flow direction of water in the inner pipe.

Images