JPH0996443A - Heat-exchanger for hot water supplying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-exchanger for hot water supplying apparatus, which can prevent the reduction of a temperature right after the resumption of a hot water supplying after the usage of the hot water supplying is shut off, from generating. SOLUTION: A heat absorbing pipe of a heat-exchanger consists of a plurality of paths 12-22 being connected by fins 15, and combining pipes 24-32 which connect between respective paths. To the fourth combining pipe 30, a by-pass pipe 17 which is branched from a water supplying pipe is joined. The heat absorbing quantity for the upstream side part from the fourth combining pipe 30 of the heat absorbing pipe, is selected from a range from 30% to 65% of the heat absorbing quantity of the overall heat absorbing pipe. The ratio of the flow rate of the by-pass pipe 17 to the total flow rate is set at 0.50. The internal diameters of the first path 12-the fourth path 18 are set smaller than the internal diameters of the fifth path 20 and the sixth path 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger for a water heater that heats supplied water into hot water and supplies the water to a bathtub, a hot water faucet, or the like.

[0002]

2. Description of the Related Art Conventionally, a plurality of fins are arranged side by side in a heat absorbing portion so that water supplied to a water heater can efficiently receive heat in a heat absorbing portion heated by combustion exhaust of a burner. There is known a heat exchanger having a structure in which a heat-absorbing tube for instantaneously heating supplied water is bent in a zigzag manner so as to cross each heat-absorbing portion many times while penetrating each fin. A plurality of parts of the heat absorption tube that crosses the heat absorption part will be referred to as "passes"
Call. In this heat exchanger, while hot water is being used, the water in the water supply pipe is heated and rises in temperature each time it passes through each path, and the hottest (= set hot water temperature) is reached at the outlet of the most downstream path communicating with the hot water supply pipe. Take a bath.

[0003]

By the way, when the use of the hot water supply in the heat exchanger is interrupted, the movement of the water in the heat absorption tube is stopped at that time. However, since the fins are generally made of a material having a high thermal conductivity such as a copper plate, the heat near the outlet of the most downstream path (exit of the heat absorbing portion) is
Since it is transmitted to other parts via each fin, the water temperature in the heat absorbing part is gradually made uniform. Therefore, as shown in FIG. 1, for example, the water temperature at the outlet of the most downstream path indicated by reference numeral 6 when the use of hot water supply is interrupted is approximately 25 ° C., which is the water temperature during steady tapping (when hot water is being used). The temperature is lower than about 40 ° C. (Note that reference numeral 1 indicates the most upstream path communicating with the water supply pipe,
Reference numerals 2 to 5 indicate respective paths provided between the paths 1 and 6).

Therefore, when hot water supply is resumed in this state, even if heating of the heat absorbing portion is promptly restarted, the hot water outlet temperature is kept until the temperature distribution where the water temperature at the outlet of the most downstream path becomes the highest temperature is formed. However, there is a problem that the set hot water temperature is not reached and the user such as a shower is uncomfortable.

Therefore, a bypass pipe for bypassing the heat absorption pipe and a flow control valve for controlling the bypass flow ratio are provided in this bypass pipe, and a part of the feed water is caused to flow through the bypass pipe to keep the water temperature in the heat absorption portion high. At the same time, a heat exchanger having a structure that prevents a decrease in hot water temperature when tapping hot water again was proposed.

However, since the flow control valve is expensive, it can only be used in high-end models. Therefore, a method has been proposed in which the bypass flow ratio is controlled to be constant without providing the flow control valve in the bypass pipe.

Also in this method, the average water temperature in the heat absorbing portion during the hot water supply interruption is shown in FIG. 1 by flowing a part of the water supply to the bypass pipe side at a predetermined flow rate ratio, as shown in FIG. It can be maintained at a higher temperature (30 ° C). But,
Actually, after the hot water supply is interrupted, the water from the bypass pipe is mixed with the hot water from the endothermic pipe at the same ratio as in the steady hot water immediately after the hot water is again discharged, and the hot water temperature after mixing is the same as that when there is no bypass pipe. Therefore, the hot water temperature immediately after the re-hot water was 25 ° C. as in the above case, and there was no effect of preventing the decrease in the hot water temperature immediately after the hot water was re-poured.

Therefore, an object of the present invention is to provide a bypass pipe for bypassing a part of an endothermic pipe for heating water supply without providing a flow control valve for controlling a bypass flow ratio, It is to provide a heat exchanger of a water heater capable of preventing a decrease in hot water temperature immediately after re-hot water is discharged.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides an endothermic pipe which has a starting end connected to a water supply pipe and an end connected to a hot water supply pipe and is formed so as to form one water passage as a whole. A heat exchanger of a hot water supply device provided with a bypass pipe that directly connects a water supply pipe and a specific portion of a heat absorption pipe. The specific location is located upstream of the end of the heat absorbing tube, and the amount of heat absorbed from the starting end of the heat absorbing tube to the specific location is 30% or more of the amount of heat absorbed by the entire heat absorbing tube. It has been selected.

In one aspect of the present invention, the specific location is selected so that the heat absorption amount from the starting end to the specific location is 30% or more and 60% or less of the heat absorption amount of the entire endothermic tube.

In another aspect, the amount of heat absorption from the starting end to a specific location is selected to be 60% to 60% of the amount of heat absorption of the entire heat absorption tube.

In another aspect, the heat absorption tube is formed so that the inner diameter on the upstream side of the specific location is smaller than that on the downstream side.

In another aspect, the inner diameter of the bypass pipe is selected so that the amount of water flowing in the bypass pipe is equal to or less than the amount of water flowing in a portion upstream of the specific portion of the heat absorbing pipe.

Further, in another aspect, a second bypass pipe is provided which directly connects the water supply pipe and a portion of the heat absorption pipe upstream of the specific portion.

According to the present invention, as the specific portion to which the bypass pipe is connected, it is upstream of the end of the heat absorbing pipe,
Moreover, the average water temperature of the endothermic pipe can be increased while hot water supply is interrupted by selecting a position where the amount of heat absorbed on the upstream side of the specific location is 30% or more of the amount of heat absorbed by the whole endothermic pipe. In addition, since it is possible to prevent the feed water from being directly mixed into the hot water discharged from the endothermic pipe, the hot water temperature immediately after re-hot water can be raised. From this point of view,
The above-mentioned specification is made at a position corresponding to an endothermic amount of at least 30% to 60% of the endothermic amount of the whole endothermic pipe, or a position corresponding to an endothermic amount of 60% to 60% of the total endothermic amount. The location is selected.

Further, according to one aspect of the present invention, the heat absorbing pipe is formed so that the inner diameter on the upstream side of the specific portion is smaller than that on the downstream side, so that the flow velocity of the water supply at the upstream portion is prevented from decreasing. Therefore, it is possible to prevent a reduction in the heat transfer rate from the heat absorbing tube to the water supply. Therefore, it becomes easy to prevent local boiling in the heat absorbing tube.

According to another aspect, since the flow rate of the bypass pipe is equal to or less than the flow rate of the upstream side of the specific location of the heat absorption tube, the upstream of the specific location is similar to the above. It is possible to prevent a decrease in the flow velocity of the water supply at the side portion, and prevent a decrease in the heat transfer rate from the heat absorbing tube to the water supply. for that reason,
It becomes easy to prevent local boiling in the heat absorption tube.

Further, according to another aspect, since the second bypass pipe which directly connects the water supply pipe and the upstream side of the specific location of the heat absorption pipe is provided, the water supply is performed by the second bypass pipe. It is possible to further raise the hot water temperature at the part of the heat absorption tube bypassed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a block diagram showing the overall structure of a water heater to which one embodiment of the present invention is applied.

The water heater has a heat exchanger 7 which is heated by combustion and exhaust from a burner (not shown), and a heat absorbing pipe 13 which pipes water from a water supply source (not shown) into the heat exchanger 7.
The water supply pipe 1 for supplying the water (see FIG. 4) and the water flow sensor 3 for detecting the water flow in the water supply pipe 1 are provided. The water heater also supplies hot water from a drum cooling unit 5 for cooling a burner (not shown) and the like, a heat exchanger 7 (heat absorbing tube 13) to a bathtub, a hot water tap (not shown), and the like. A hot water supply pipe 9 is also provided.

In the above structure, when it is determined by the detection signal from the water flow sensor 3 that there is water flow of a predetermined flow rate or more, a controller (not shown) which controls each part of the water heater.
Performs burner (not shown) combustion control so that hot water at a hot water temperature set value set by a temperature setting unit (not shown) can be obtained from the heat exchanger 7.

FIG. 4 shows the detailed structure of the heat exchanger 7 of FIG.

The heat exchanger 7 is bent in a meandering shape as a whole a plurality of times so as to traverse the heat absorbing portion 11 and the heat absorbing portion 11 for receiving the combustion exhaust gas of the burner, and the hot water is supplied from the water supply pipe 1 through the hot water. One endothermic tube 13 is provided. The heat exchanger 7 connects a plurality of fins 15 arranged in parallel in the heat absorbing portion 11 in order to enhance the heat transfer property of the entire heat absorbing tube 13, a downstream end of the water supply tube 1 and a portion of the heat absorbing tube 13 near the downstream side. Also provided is a bypass pipe 17 configured to allow a part of the water, which is about to flow into the heat absorption pipe 13 from the most upstream side, to flow in from a portion of the heat absorption pipe 13 near the downstream side.

The endothermic tube 13 is configured so that a plurality of parts (paths) crossing the endothermic portion 11 in a substantially parallel manner and one pipe (that is, the endothermic tube 13) are formed as a whole by connecting each path. It is composed of a plurality of coupling pipes that are curved in a substantially U shape.

In the present embodiment, the heat absorption tube 13 is provided with six paths and five coupling tubes as shown in the figure. Therefore, in the following description, regarding each of the above-mentioned paths, the most upstream path communicating with the water supply pipe 1 is the first path 12, and the most downstream path communicating with the hot water supply pipe 9 is the sixth (final) path 22. ,
Each of the paths between the first path 12 and the sixth path 22 is arranged from the upstream side to the downstream side in order of the second path 14, the third path 16,
These are called the fourth pass 18 and the fifth pass 20. On the other hand, regarding each coupling pipe, a coupling pipe that connects the first pass 12 and the second pass 14 is a first coupling pipe 24, and a fifth pass 20 and a sixth pass 22.
The connecting pipes for connecting the fifth connecting pipe 32 and the first connecting pipe 24
And the fifth coupling pipe 32, the second coupling pipe 26, the third coupling pipe 28, and the fourth coupling pipe 32 in order from the upstream side to the downstream side.
It is referred to as a coupling tube 30.

In this embodiment, as shown in FIG.
The coupling pipe 30 is a confluence part of the bypass pipe 17.
Then, the first path 12 to the fourth path on the upstream side of the confluence portion.
The inner diameters of the paths 18 are set to the fifth path 20 and the sixth path 20 in order to prevent a decrease in the flow rate of the feed water in each of these paths and a decrease in the heat transfer rate of the heat transferred from each path to the feed water due to the decrease in the flow rate.
The diameter is set smaller than the inner diameter of the path 22.

As shown in FIGS. 5 and 6, each fin 15 is penetrated by all of the first pass 12 to the sixth pass 22, whereby the first pass 12 to the sixth pass 22 are respectively passed. Are thermally coupled to each other via the fins 15 of the.
That is, when the burner (not shown) is combustion-controlled by the controller (not shown) and the heat from the burner is given to each fin 15, the first pass 12 to the sixth pass 22 pass from each fin 15 to each other. It takes away the heat transferred and heats the water passing through each path. On the other hand, from the water supply source to the water supply pipe 1
When the combustion of the burner is stopped due to the stop of water flow to the water, heat from the hottest hot water in the sixth pass 22 and heat from the relatively hot water in the fifth pass 20 and the fourth pass 18 respectively The coldest water in the first pass 12 through the fins 15 of the
The water is transferred to the relatively low temperature water in the path 14 and the third path 16. As a result, the temperature in the heat exchanger 7 gradually becomes uniform.

In the present embodiment, the bypass flow rate of the hot water supply is adjusted so that the highest average water temperature can be obtained in the heat absorbing section 11 immediately after the hot water is again used after the hot water supply is interrupted, and the hot water can be discharged at the high average water temperature. A bypass pipe 17 having a ratio set to 0.5 is adopted, and the water supply pipe 1 and the fourth coupling pipe 30 are directly connected via the bypass pipe 17. Therefore, only 0.5 of the remaining feed water flows into the first pass having the lowest temperature, which causes the average water temperature in the heat absorbing portion 11 to rise to some extent.

Here, if the bypass flow ratio of the bypass pipe 17 is 0.5, the flow velocity of the feed water in the first pass 12 to the fourth pass 18 upstream of the fourth coupling pipe 30 does not decrease so much, and The heat transfer rate from each pass to the water supply does not decrease. Therefore, the temperature in the first pass 12 to the fourth pass 18 does not rise, and local boiling does not occur, which causes a problem that noise is increased. Therefore, in order to prevent local boiling, it is desirable that the bypass flow rate ratio is not too large.

Next, by setting the merging position of the bypass pipe 17 having the above-mentioned structure to the fourth connecting pipe 30, the reason why the hot water with the highest average water temperature can be obtained immediately after the re-hot water after the interruption of the hot water supply use is obtained. This will be described with reference to FIG.

In FIG. 7, the broken line (straight line) 19 shows the bypass flow rate of the hot water supply, and the solid line (curve) 21 shows the average water temperature in each (6) passes when hot water supply is interrupted. From the figure, in order to obtain an average water temperature of 30 ° C. or higher, the bypass flow rate ratio is set to about 0.7, and the joining position is indicated by reference numeral 25 so that at least 30% of the amount of heat absorbed by the entire endothermic tube 13 can be obtained. Near the exit of the second pass 14, or the bypass flow ratio is about 0.3 and the confluence position is the final pass 2.
You can see that it is better to move closer to 2.

Further, in order to set the average water temperature to about 32 ° C. (maximum value) indicated by reference numeral 23, the bypass flow rate ratio is set so as to obtain at least 60% to 60% of the amount of heat absorbed by the entire heat absorbing tube 13. It is understood that it is sufficient to set 0.5 and the merging position near the exit of the fourth pass 20. This is (1) below
It is also supported by the formula. In the following, description will be given using this equation (1). (THmax-TC) / 2 (TSmax-TC) (1) However, TC: feed water temperature value, TSmax: maximum set hot water temperature value, TH
max: temperature value of the heat absorbing tube 13 immediately before the water in the bypass tube 17 merges with the hot water in the heat absorbing tube 13, and TS (set hot water temperature value)
= Tsmax is a temperature value at which boiling does not occur.

Here, TSmax = 75 ° C. and THmax = 90 ° C.
If TC = 5 ° C. due to the winter season, then substituting these values into equation (1) gives (90−
5) / 2 (75-5) = 0.607 is obtained. Also,
Both TSmax and THmax are the same as the above values, and T
If C = 20 ° C, these values should be calculated as in (1) above.
By substituting into the formula, (90-20) / 2 (75-
20) = 0.636 is obtained. From this calculation result, the bypass pipe is connected so that the ratio of the heat absorption amount of the heat absorption pipe on the upstream side of the confluence position of the bypass pipe to the heat absorption amount of the entire heat absorption pipe is about 60% to about 60%. It is understood that the coupling tube should be selected. That is, in the heat exchanger having six passes as in the present embodiment, the confluence position of the bypass pipes 17 is the fourth coupling pipe 30 located at the outlet of the fourth pass 20, and the description of FIG. To match.

According to the above construction, the merging portion of the bypass pipe 17 is set to the fourth coupling pipe 30 capable of obtaining an endothermic amount of about 60 to 60.55 minutes with respect to the total endothermic amount of the endothermic pipe 13. Therefore, the average water temperature in the heat absorbing part 11 during the hot water supply interruption is higher than 25 ° C. shown in FIG. 1 and 30 ° C. shown in FIG.
It becomes 2 degreeC (refer FIG. 8). This value is a temperature close to 30 ° C. in FIG. However, in the above configuration, as in the heat exchanger described in FIG. 2, the hot water from the heat absorbing portion and the water from the bypass pipe are not mixed at the outlet of the heat absorbing portion, and the confluent portion of the bypass pipe is at or near the final path. Since there is no risk that water will mix into hot water such as the heat exchanger set in the part, immediately after re-hot water,
Pour hot water at 32 ° C, which is the average water temperature in the heat absorbing part. Therefore, it is possible to prevent a decrease in the hot water discharge temperature immediately after re-hot water discharge after interruption of hot water supply use.

In the present embodiment, the highest average water temperature (32 ° C.) is obtained immediately after the hot water is re-extracted, and the high water temperature is maintained at the high average water temperature. Although the pipe 30 is used, the average water temperature and the tap water temperature should be 30 ° C. even if the merging portion is near the outlet of the second pass 14 (the second coupling pipe 26) where an endothermic amount of at least about 30% can be obtained. (See FIG. 7). Considering that there is no risk that the water supply mixes with the hot water, and that the undershoot can be reduced by increasing the chances that the water supply absorbs heat, the confluence portion is defined as the heat absorbing portion 11.
It is desirable to set it on the upstream side of the vicinity of the exit of the fourth pass 20 so that the distance to the exit can be increased.

FIG. 9 shows a heat exchanger to which another embodiment of the present invention is applied.

The difference between the present embodiment and the above-mentioned one embodiment is that the heat exchanger according to the present embodiment further increases the average water temperature in the heat absorbing portion by the above-mentioned bypass pipe (hereinafter,
In addition to the first bypass pipe 17), the water supply pipe 1 and the second
The second bypass pipe 19 is also provided so as to directly connect to the second coupling pipe 26 at the exit of the path 14. In this second bypass pipe 19, the bypass flow ratio of the feed water is 0.
It uses 3 items.

According to the above configuration, in addition to the first bypass pipe 17, the second bypass pipe 19 that directly connects the water supply pipe 1 and the second coupling pipe 26 is also provided. The average water temperature in the exchanger 7 is 35 ° C., which is higher than 32 ° C. shown in FIG. 8 (see FIG. 10). In the present embodiment, as in the heat exchanger described in FIG. 2, the hot water from the heat absorbing tube and the water from the bypass tube are not mixed at the outlet of the heat absorbing section. The water will be discharged at the water temperature of 35 ° C. Therefore, also in the present embodiment, similarly to the one embodiment, it is possible to prevent a decrease in the hot water discharge temperature immediately after the re-hot water discharge after the use of hot water supply is interrupted.

11 to 13 show first to third modified examples according to other embodiments of the present invention.

Although the heat exchanger shown in each of the above figures is provided with four paths for convenience of illustration, it is theoretically different from the heat exchanger of another embodiment having six paths. There is no point.

First, in the heat exchanger of FIG. 11, the first pass 5
The first bypass pipe 57 that joins the first coupling pipe 55 that connects the first and second passes 53, and the second bypass pipe 6 that joins the second coupling pipe 61 that connects the second pass 53 and the third pass 59.
3, the third bypass pipe 69 that joins the third coupling pipe 67 that connects the third pass 59 and the fourth pass 65, and the fourth bypass pipe 71 that joins the outlet of the fourth pass 65 are piped.

Next, in the heat exchanger of FIG. 12, the first pass 7
The first bypass pipe 79 that joins the first coupling pipe 77 that connects the third pass 75 and the third bypass 81, and the second bypass pipe 8 that joins the second coupling pipe 83 that connects the second pass 75 and the third pass 81
5. A third bypass pipe 91 is joined to a third coupling pipe 89 that connects the third pass 81 and the fourth pass 87.

Further, in the heat exchanger of FIG. 13, the first pass 9
The first bypass pipe 99 and the first pass 9 that branch from the first coupling pipe 97 that connects the third path 101 and the third path 101 and join the second coupling pipe 103 that connects the second path 95 and the third path 101.
A second bypass pipe 107 that branches from the inlet of No. 3 and joins with the outlet of the fourth pass 105 is provided.

In each of these modified examples, a plurality of bypass pipes are provided in different manners, and in each case, the average water temperature in the heat absorbing portion is further raised to further improve the hot water dischargeability immediately after the re-hot water is discharged. It is also possible to prevent the generation of drain in the heat absorption tube.

Next, comparing the heat exchanger according to the embodiment of the present invention with the two types of heat exchangers according to the prior art,
The reason why the heat exchanger according to the embodiment of the present invention is superior to the two types of heat exchangers according to the related art will be described with reference to FIGS. 14 to 18. In the following description, for simplification, in each of the embodiments and the related art, a heat exchanger in which the number of passes of the heat absorbing tube is “4” will be described as an example.

First, the surface temperature Tw of the heat absorbing tube is obtained by the following equation (2) (see also FIG. 14).

[0048]

[Equation 1] The equation (2) is used to determine the wall temperature of the heat absorbing tube (= temperature higher than the dew point of the combustion gas) capable of preventing the generation of drain (water droplets) in the heat absorbing tube.
This equation (2) shows that the wall temperature of the endothermic tube rises when the amount of water passing through the endothermic tube decreases (that is, the bypass flow rate of the feed water is large), and the wall temperature of the endothermic tube rises when the hot water temperature is high. Is shown.

Here, the set hot water temperature value (TS) is set to a relatively high temperature of 75 ° C. where the bypass flow rate ratio cannot be increased, and the feed water temperature value (TC) is set to a relatively low temperature of 5 ° C. where the bypass flow rate ratio cannot be increased. , The maximum hot water temperature (THmax) in the heat absorption tube
90 ° C that does not cause local boiling in the endothermic tube
, Set each. These respective conditions are derived from the fact that the so-called temperature control type mainstream hot water heaters in recent years are the mainstream. Then, the bypass flow rate ratio α to the bypass pipe of the feed water is obtained using the following formula (3), and the hot water temperature in the heat absorbing pipe at the time of tapping at the set hot water temperature of 40 ° C is calculated using the formula (2). ,
The effects of the respective embodiments and the effects of the above-described conventional technique will be compared with reference to FIGS. α = 1-{(hot water temperature immediately after the bypass water supply and hot water in the heat absorption pipe join-feed water temperature) / (hot water temperature just before the bypass water supply and hot water in the heat absorption pipe join-feed water temperature)} ... (3) Here, in each heat exchanger shown in FIGS. 15 to 17, assuming that the heat absorption rates of all the paths are the same (that is, 25%), the bypassed water supply and the hot water in the heat absorption pipe are The temperature of the hot water immediately before the joining is set to 90 ° C, and the water temperature (supply water temperature) at the branch point A between the first pass and the bypass pipe is set to 5 ° C.

First, in the conventional heat exchanger shown in FIG. 15, if the temperature of the hot water immediately after the bypassed feed water and the hot water in the heat absorption pipe are joined is 75 ° C., the bypass flow rate ratio α of the bypass pipe 135 is (3 ), Α = 1-{(75-5) / (9
0-5)} = 0.176. Next, the bypass pipe 13
Point F of hot water supply pipe 137 located on the downstream side of the confluence part of 5
If the hot water temperature at 40 ° C. is 40 ° C., the hot water temperature at the point E located on the upstream side of the confluence portion of the fourth pass 131 is E = {F (F−A) / (1 −α)} + A = {(40
-5) / (1-0.176)} + 5 = 47.5, 4
It is 7.5 ° C.

Further, the hot water temperature at the point D of the third coupling pipe 133 connecting the third pass 127 and the fourth pass 131 is D = E
-(EA) x 0.25 (= endothermic coefficient) = 47.5- (4
7.5-5) × 0.25 = 36.9, which is 36.9 ° C. Further, the hot water temperature at the point C of the second coupling pipe 129 connecting the second path 123 and the third path 127 is C = D- (E-
A) × 0.25 = 36.9− (47.5-5) × 0.2
5 = 26.3 and 26.3 ° C. Furthermore, the first pass 1
21 at the point B of the first coupling pipe 125 connecting the second path 123 to the second path 123, B = C− (EA) × 0.25 = 2
6.3- (47.5-5) × 0.25 = 15.7, which is 1
It is 5.7 ° C. In this way, the hot water temperatures at points B to E are obtained respectively.

Next, in the conventional heat exchanger shown in FIG. 16, the hot water temperature at the point F which is the outlet of the fourth pass 153 is set to 75 ° C.
Then, the hot water temperature at the point D of the second coupling pipe 149 located on the downstream side of the confluence portion of the bypass pipe 151 is D = F−
(F−A) × 0.50 = 75− (75−5) = 40,
40 ° C. Since the hot water temperature is the hot water temperature immediately after the bypass water supply and the hot water in the heat absorption pipe are joined, the bypass flow rate ratio α of the bypass pipe 151 is α = 1 − {(40
-5) / (90-5)} = 0.59.

If the hot water temperature at the point F is set to 40 ° C., the hot water temperature at the point E of the third connecting pipe 155 connecting the third pass 147 and the fourth pass 153 is E = F- (F-
A) × 0.25 = 40− (40−5) × 0.25 = 3
1.3 and 31.3 ° C. Further, the hot water temperature at the point D is D = E- (FA) × 0.25 = 31.3− (4
0-5) × 0.25 = 22.6, which is 22.6 ° C.
Further, the hot water temperature at the point C located on the downstream side of the second path 143 (= the hot water temperature immediately before the bypass water supply and the hot water in the heat absorption pipe are joined)
Is C = {(D−A) / (1−0.5) according to the equation (2).
9)} + 5 = {(22.6-5) / (1-0.59)}
It is + 5 = 48 and is 48 degreeC. Furthermore, the hot water temperature at the point B of the first coupling pipe 145 connecting the first path 141 and the second path 143 is B = C− (CA) × 0.5 = 48− (48
−5) × 0.5 = 26.5, which is 26.5 ° C. In this way, the hot water temperatures at points B to E are obtained respectively.

Next, in the heat exchanger of the embodiment of the present invention shown in FIG. 17, if the hot water temperature at the point G, which is the outlet of the fourth pass 173, is 75 ° C. Pass 17
Bypass flow rate ratio β of the second bypass pipe 177 that joins
Is β = 1 − {(75−5) / (90−) according to the equation (3).
5)} = 0.176.

The hot water temperature at the point D of the second coupling pipe 171 on the downstream side of the confluence of the first bypass pipe 167 is the fourth.
Since the hot water temperature at the point F on the downstream side of the confluence portion of the second bypass pipe 177 of the path 173 is 90 ° C., D = F−
(F−A) × 0.50 = 90− (90−5) × 0.50
= 47.5, which is 47.5 ° C. Further, the bypass flow rate ratio α of the first bypass pipe 167 is α = 1 based on the equation (3).
-{(47.5-5) / (90-5)} = 0.50.

If the hot water temperature at the point G is set to 40 ° C., the hot water temperature at the point F is F = {(G
-A) / (1-β)} + A = {(40-5) / (1-
0.176)} + 5 = 47.5, which is 47.5 ° C.
Further, the hot water temperature at the point E of the third coupling pipe 175 is E = F-
(F−A) × 0.25 = 47.5− (47.5−5) ×
It is 0.25 = 36.90 and is 36.90 degreeC. Also,
The hot water temperature at the point D is D = E- (FA) × 0.25 = 3
6.90- (47.5-5) x 0.25 = 26.30
And 26.30 ° C. Also, point C of the second pass 163
(A part upstream of the confluence part of the first bypass pipe 167)
The hot water temperature at C = {(DA) / (1-
α)} + A = {(26.3-5) / (1-0.50)}
It is + 5 = 47.60 and is 47.60 degreeC. Furthermore, the first
The hot water temperature at the point B of the coupling pipe 165 is B = C- (CA) ×
0.50 = 47.60- (47.60-5) x 0.50
= 26.3, which is 26.3 ° C. In this way, the hot water temperatures at points B to F are obtained respectively. Note that FIG.
In, the reference numeral 161 is the first pass, and the reference numeral 169 is the third pass.

Here, comparing the heat exchanger of the embodiment (FIG. 17) with the heat exchanger of FIG. 15, in the heat exchanger of the embodiment, a part of the first bypass pipe 167 and the second bypass pipe 177 are compared. Although the first pass 161 to the fourth pass 173 are bypassed, the bypass flow rate ratio is shown in FIG.
It can be set larger than that of the bypass pipe 135. Therefore, in FIG. 18 (each temperature value is plotted), as shown by the straight line 181 and the straight line 183, in the section from the third pass inlet to the fourth pass outlet, the hot water temperatures are almost equal to each other, In the section from the first pass inlet to the second pass outlet, the hot water temperature of the heat exchanger according to the embodiment is higher than that of the heat exchanger of FIG. Therefore, as a whole, the heat exchanger according to the embodiment can raise the average water temperature higher than that of the heat exchanger of FIG. 15, and in particular, due to the high average water temperature for several minutes (for example, It is possible to improve the hot water discharge property when the hot water is again discharged after the hot water supply is interrupted for 5 minutes, and the drain preventing effect can be further improved.

On the other hand, comparing the heat exchanger of the embodiment (FIG. 17) with the heat exchanger of FIG. 16, at least the bypass flow rate ratio of the first bypass pipe 167 is as follows.
1st bypass pipe 1 without being much smaller than that of 51
1st pass 1 by a part of 67 and the 2nd bypass pipe 177
The 61st to 4th paths 173 can be bypassed. Therefore, as shown by a straight line 181 and a straight line 185 in FIG. 18, in the section from the first pass inlet to the second pass outlet, the hot water temperatures are substantially the same in both sections, but the section from the third pass inlet to the fourth pass outlet Then, the hot water temperature of the heat exchanger according to the embodiment is higher than that of the heat exchanger of FIG. 16. Therefore, as a whole, the heat exchanger according to the embodiment can raise the average water temperature higher than that of the heat exchanger of FIG. 16 as in the case described above, and in particular, due to the high average water temperature. It is possible to improve the hot water discharge property when the hot water is again discharged after the hot water supply is interrupted for several minutes, and further improve the drain prevention effect.

It goes without saying that the contents described above relate to one embodiment of the present invention, and the present invention is not limited to the above contents.

[0060]

As described above, according to the present invention,
Even if a flow control valve that controls the bypass flow rate ratio is not installed in the bypass pipe that bypasses a part of the heat absorption pipe for heating the water supply, the hot water temperature is prevented from decreasing immediately after the hot water is re-used after the hot water supply is interrupted. It is possible to provide a heat exchanger of a hot water supply device that can be used.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a state of hot water temperature in each pass of a conventional heat exchanger.

FIG. 2 is an explanatory view showing a state of hot water temperature in each pass of the conventional heat exchanger.

FIG. 3 is a block diagram showing an overall configuration of a water heater according to an embodiment.

FIG. 4 is an explanatory diagram showing a detailed configuration of the heat exchanger of FIG.

FIG. 5 is an explanatory diagram showing a positional relationship between a fin and each path.

FIG. 6 is an explanatory diagram showing a positional relationship between a fin and each path.

FIG. 7 is an explanatory diagram showing a state of average water temperature and a bypass flow rate ratio in each pass.

FIG. 8 is an explanatory view showing a state of hot water temperature in each pass of the embodiment.

FIG. 9 is an explanatory diagram showing a detailed configuration of a heat exchanger of another embodiment.

FIG. 10 is an explanatory view showing a state of hot water temperature in each pass of another embodiment.

FIG. 11 is a diagram showing a heat exchanger of a first modified example of another embodiment.

FIG. 12 is a diagram showing a heat exchanger of a second modified example of another embodiment.

FIG. 13 is a diagram showing a heat exchanger of a third modified example of another embodiment.

FIG. 14 is an explanatory diagram related to an equation for obtaining the surface temperature of the heat absorbing tube.

FIG. 15 is a diagram showing a configuration of a conventional heat exchanger.

FIG. 16 is a diagram showing a configuration of a conventional heat exchanger.

FIG. 17 is a diagram showing the configuration of the heat exchanger of the embodiment.

FIG. 18 is a diagram comparing hot water temperatures in respective passes between the embodiment and the related art.

[Explanation of symbols]

 1 Water Supply Pipe 7 Heat Exchanger 9 Hot Water Supply Pipe 11 Endothermic Part 12 First Pass 13 Endothermic Pipe 14 Second Pass 15 Fin 16 Third Pass 17 Bypass Pipe 18 Fourth Pass 20 Fifth Pass 22 Sixth Pass 24 First Coupling Pipe 26 second coupling pipe 28 third coupling pipe 30 fourth coupling pipe 32 fifth coupling pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Mikio Ochi Inventor Mikio Ochi 43-1, Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Nihon Yupro Co., Ltd. (72) Inventor Yasuhisa Ohira 43-1, Uozakihama-cho, Higashinada-ku, Kobe No. Nihon Yupro Co., Ltd. (72) Inventor Kiyotaka Nakano 43-1 Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Prefecture Nihon Yupro Co., Ltd. (72) Inventor Toru Tsuruta 43-1, Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Prefecture Issue Nihon Yupro Co., Ltd. (72) Inventor Hiroki Maruyama 43-1, Uozakihama-cho, Higashinada-ku, Kobe-shi, Hyogo Prefecture Nihon Yupro Co., Ltd. (72) Inventor Takayuki Otani 43-1, Uozakihama-cho, Higashinada-ku, Hyogo Prefecture Issue Nihon Yupro Co., Ltd.

Claims (6)

[Claims] 1. A heat exchanger for a water heater, comprising a heat absorption pipe having a start end connected to a water supply pipe and an end end connected to a hot water discharge pipe and formed as one water passage as a whole, A bypass pipe that directly connects the water supply pipe and a specific portion of the heat absorbing pipe is provided, and the specific portion is a position on the upstream side of the end of the heat absorbing pipe, and from the start end of the heat absorbing pipe to the specific place. The heat exchanger of a water heater, wherein the specific portion is selected so that the amount of heat absorbed between them is 30% or more of the amount of heat absorbed by the entire heat absorption tube. 2. The heat exchanger of the water heater according to claim 1, wherein an endothermic amount from a starting end of the endothermic pipe to the specific portion is 30% or more and 60% or less of an endothermic amount of the entire endothermic pipe. As described above, the heat exchanger of the water heater, wherein the specific location is selected. 3. The heat exchanger of a water heater according to claim 1, wherein an endothermic amount from a start end of the endothermic pipe to the specific location is 60% or more and 60% or less of an endothermic amount of the entire endothermic pipe. The heat exchanger of the water heater, wherein the specific location is selected so that 4. The heat exchanger of a water heater according to any one of claims 1 to 3, wherein the heat absorption pipe has an inner diameter on the upstream side of the specific location smaller than that on the downstream side. And the heat exchanger of the water heater. 5. The heat exchanger of a water heater according to any one of claims 1 to 4, wherein the amount of flowing water in the bypass pipe is a amount of flowing water in a portion of the heat absorption pipe upstream of the specific portion. The heat exchanger of the water heater, wherein the inner diameter of the bypass pipe is selected so as to be equal to or less than. 6. The heat exchanger of a water heater according to any one of claims 1 to 5, wherein the water supply pipe and the second end of the heat absorption pipe are directly connected to each other at a position upstream of a specific position. A heat exchanger for a water heater, further comprising a bypass pipe.