JP3777255B2 - Heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called bypass mixing type heat exchange apparatus that takes out hot water at a desired temperature by mixing cold water into high-temperature water boiled in a heat exchanger.
[0002]
[Prior art]
There is a bypass mixing type heat exchange device having a structure as shown in FIG. 4 that prevents high-temperature water from flowing out of a tap hot water tap when the hot water is discharged immediately after the hot water is stopped. A gas burner (11) is accommodated in the combustion box (12) connected to the discharge port of the air supply fan (10), and a can of the heat exchanger (2) is located above the combustion box (12). The body (21) is connected. A heat exchanging portion (20) comprising a group of heat absorbing fins (22) and (22) and a heat absorbing pipe (23a) penetrating through the can body (21) is provided.
[0003]
A water supply pipe (23b) and a tapping pipe (23c) extending separately on the upstream side and the downstream side of the heat absorption pipe (23a) are connected by a bypass pipe (26), and the tapping pipe (23c) and the bypass pipe The junction (G) of (26) is provided with a flow rate ratio setting device (41) for setting the mixing ratio of hot water from the heat exchanger (2) and cold water from the bypass pipe (26).
Further, an exhaust collecting cylinder (31) having an exhaust port (32) is connected to the upper portion of the heat exchanger (2).
[0004]
In this case, when the hot water tap (51) is opened, it is based on the temperature set by a hot water temperature setter (not shown), the amount of hot water measured by the flow rate counter (53), the incoming water temperature detected by the water temperature sensor (52), etc. Thus, the required combustion amount of the gas burner (11) is calculated, and the gas burner (11) is feedforward controlled. Then, the water flowing through the heat absorption pipe (23a) of the heat exchange section (20) is heated by the gas burner (11), and the hot water boiled by this is bypassed in the flow rate ratio setting unit (41) part. The cold water from (26) is mixed, whereby hot water adjusted to the set temperature is supplied to the hot water tap (51) side.
[0005]
In this case, even if hot water stays in the heat exchanger (2) due to the so-called post-boiling phenomenon, cold water from the bypass pipe (26) is mixed with the hot water during the subsequent re-bathing operation. There is no inconvenience that the hot water flows out from the tap (51).
[0006]
[Problems to be solved by the invention]
However, in the above conventional heat exchange device, heat is released from the peripheral wall of the can (21) of the heat exchanger (2) and heat loss occurs, so that the heat exchange efficiency cannot be sufficiently increased.
Therefore, in order to improve the heat exchange efficiency of the heat exchange device, as shown in FIG. 5, the water supply pipe (23b) on the upstream side of the heat absorption pipe (23a) is connected to the can (21) of the heat exchanger (2). The water stored in the outer peripheral wall of the can body (21) is absorbed by the water in the water supply pipe (23b), but the can body (21) is the water supply pipe (23b) Therefore, the combustion exhaust coming into contact with the inner surface of the wound portion (34) of the can body (21) around which the water supply pipe (23b) is wound is cooled to condense, and the condensed water is added to the condensed water. There is a concern that the can (21) is corroded by the acidic component contained.
[0007]
The present invention has been made in view of the above points, and even if heat exchange efficiency is improved by winding the water pipe on the can body (21) of the heat exchanger (2), the water pipe is wound. An object of the present invention is to prevent the occurrence of condensation on the inner surface of the wound portion (34) of the can body (21) .
[0008]
[Means for Solving the Problems]
Technical means for solving the above problems are:
`` The heat exchanger (20) provided in the can (21) of the heat exchanger (2) heated by the gas burner (11),
An auxiliary heat absorption pipe (61) connected to the downstream end of the heat absorption pipe (23a) constituting the heat exchange section (20) and wound around the outer periphery of the body of the can body (21);
A bypass pipe (26) connecting the downstream flow path of the auxiliary heat absorption pipe (61) and the upstream flow path of the heat absorption pipe (23a);
The flow rate for adjusting the mixing ratio of hot water and cold water from both pipes (61), (26) at the junction (G) of the downstream flow path of the auxiliary heat absorption pipe (61) and the bypass pipe (26) Ratio setting device (41),
A temperature sensor (63) for determining the temperature of the wound part (34) of the can (21) around which the auxiliary heat absorption pipe (61) is wound;
The flow rate ratio setter so that the mixing ratio required to make the temperature of the wound portion (34) of the can body (21) higher than the dew point of the combustion exhaust in the can body (21) can be set. Means for controlling (41) ,
The temperature sensor (63) is provided in the vicinity of the discharge portion of the heat absorption pipe (23a) ,
That is, the temperature of the wound portion (34) is regarded as a temperature slightly higher than the temperature detected by the temperature sensor (63) .
[0009]
According to the above technical means, the auxiliary heat absorption pipe (61) connected to the downstream end of the heat absorption pipe (23a) constituting the heat exchange section (20) of the heat exchanger (2) is connected to the heat exchanger (2). Since it is wound around the body portion of the can body (21), the heat exchange efficiency is improved as compared with that of FIG.
On the other hand, according to the above technical means, the auxiliary heat absorption pipe (61) connected to the downstream end of the heat absorption pipe (23a) constituting the heat exchange section (20) has a high temperature flowing out from the heat exchange section (20). Since water flows, the wall surface of the wound part (34) of the can body (21) in which the auxiliary heat absorption pipe (61) through which this high-temperature water flows is wound and in contact is kept at a high temperature above the dew point temperature. Compared to the case of FIG. 5 in which the water supply pipe (23c) through which the cold water flows is wound around the can body (21), a state in which the inner surface of the wound portion (34) is less likely to condense is ensured.
[0010]
Next, when the temperature of the wound part (34) determined by the temperature sensor (63) (which is considered to be slightly higher than the temperature detected by the temperature sensor (63) ) is lower than the dew point of the combustion exhaust, The flow rate ratio setting device (41) operates so as to decrease the water flow rate in the heat absorption pipe (23a) constituting the section (20) and increase the water flow rate in the bypass pipe (26). Thereby, the wound part (34) of the can (21) is always kept at a temperature higher than the dew point of the combustion exhaust.
[0011]
【The invention's effect】
As described above, the wound portion (34) of the can body (21) is always kept above the dew point of the combustion exhaust, so that the auxiliary heat absorption pipe (61) is connected to the can body (21) of the heat exchanger (2). The heat exchange efficiency can be improved without causing condensation of the combustion exhaust gas .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the form of the Example of this invention is demonstrated with the example of illustration.
As shown in FIG. 1, in the combustion box (12) connected to the discharge port of the air supply fan (10), all of the air supplied from the air supply fan (10) is used as primary combustion air. The used primary combustion type gas burner (11) is accommodated. A can body (21) of a heat exchanger (2) is connected to the upper side of the combustion box (12) on the downstream side of the exhaust flow, and an endothermic fin ( A heat exchanging section (20) comprising a group (22) and (22) and a heat absorption pipe (23a) penetrating the group is provided.
[0014]
The bypass pipe (26) branches off from the middle of the water supply pipe (23b) on the upstream side of the heat absorption pipe (23a) constituting the heat exchange section (20), and the bypass pipe (26) The downstream end is connected to an auxiliary heat absorption pipe (61) continuous to the water flow downstream side of the heat absorption pipe (23a) constituting the heat exchange section (20). The auxiliary heat absorption pipe (61) is wound around the body of the can (21) of the heat exchanger (2), and at the junction (G) of the bypass pipe (26), auxiliary heat absorption pipe (61) A flow rate ratio setting device (41) for adjusting the mixing ratio of hot water from the pipe (61) and cold water from the bypass pipe (26) is provided. The flow rate ratio setting device (41) can adjust the mixing ratio even if it is disposed in the bypass pipe (26) or the flow path branching portion (28) which is the upstream end of the bypass pipe (26). Can do.
[0015]
Near the water inlet (24) of the upstream water supply pipe (23b), a flow rate counter (53) for measuring the amount of water flowing into the water supply pipe (23b) and an incoming water temperature sensor (52) for detecting the incoming water temperature And a temperature sensor (63) is attached to a portion where the heat absorption pipe (23a) and the auxiliary heat absorption pipe (61) constituting the heat exchange section (20) are connected. (63) makes it possible to determine the temperature of the wound portion (34) of the can (21) ( in a high temperature state of about 4 deg, which is slightly higher than the temperature detected by the temperature sensor (63)). Furthermore, a hot water tap (51) is connected to the outlet (25) on the downstream side of the flow rate ratio setting device (41). Further, on the downstream side of the flow rate ratio setting device (41), a tapping temperature sensor for feedback control that detects the temperature of the mixed water of cold water from the bypass pipe (26) and hot water from the auxiliary heat absorption pipe (61) (Fig. Shimese not) is set vignetting.
[0016]
The flow rate counter (53), the incoming water temperature sensor (52) and the like are electrically connected to the control device (71).
In the heat exchange device according to the present embodiment, the hot water temperature set by the hot water temperature setting device (73), the flow rate (outflow amount) measured by the flow rate counter (53), and the incoming water temperature sensor (52) are detected. The feedforward control for burning the gas burner (11) with the combustion amount calculated based on the incoming water temperature is performed, and the feedback control based on the temperature detected by the tapping temperature sensor is also performed. Can be taken out from the hot spring tap (51).
[0017]
Next, the dew condensation prevention control of the wound portion (34) of the can body (21) will be described with reference to the flowchart of FIG.
When the flow counter (53) detects water flow by opening the tap tap (51), the air supply fan (10) rotates and the gas burner (11) starts to burn, and the gas burner ( The combustion amount of 11) is adjusted and the hot water operation starts.
[0018]
Next, the temperature of the wound portion (34) of the can body (21) (which is assumed to be 4 ° C. higher than the temperature detected by the temperature sensor (63) in the present embodiment) is emitted from the gas burner (11). In step (ST1), it is determined whether or not it is equal to the reference temperature set slightly higher than the dew point (in this embodiment, set to 60 ° C.). If it is equal to the reference temperature, this state is maintained. To do. On the other hand, if the temperature of the coiled part (34) (detected temperature of the temperature sensor (63) + 4 ° C) is not equal to the reference temperature, the temperature of the coiled part (34) is the above reference temperature in step (ST2). If the temperature is higher than the reference temperature, the flow rate ratio setting device (41) is controlled in step (ST3), so that the heat absorption pipe (23a) side constituting the heat exchange section (20) is controlled. While increasing the water flow rate, decrease the water flow rate of the bypass pipe (26). As a result, the temperature of the wound portion (34) of the can (21) is lowered to the reference temperature. This prevents the temperature in the endothermic tube (23a) from becoming excessively high and boiling.
[0019]
Now, when the temperature of the wound part (34) becomes lower than the reference temperature due to a sudden drop in the temperature of the tap water flowing into the heat exchanger (2), the wound part ( There is concern that condensation will form on the inner surface of 34). Then, the control operation shifts from step (ST2) to step (ST4), and the flow rate ratio setting device (41) operates so as to reduce the amount of water passing through the heat absorption pipe (23a) constituting the heat exchange section (20). To do.
[0020]
By controlling in this way, the temperature of the wound portion (34) of the can body (21) is always kept at or above the dew point of the combustion exhaust, and there is no fear that condensation will occur at that portion.
[Others]
1. In the above embodiment, the heat exchange device of the type in which the heat exchanging portion (20) of the heat exchanger (2) is disposed above the gas burner (11) has been exemplarily described, but the heat exchange device of FIG. Needless to say, the present invention can also be applied to a structure in which the heat exchanger (2) is positioned below the gas burner (11), that is, the heat exchange apparatus of the type shown in FIG.
[0023]
2. In the above implementation, all of the supply air supplied by the air supply fan (10) is illustrated heat exchange apparatus in which all primary combustion of the gas burner to be used (11) is incorporated as primary air for combustion Needless to say, the present invention can be applied to a heat exchange apparatus incorporating a Bunsen burner.
[0024]
In the Bunsen burner type heat exchange device, a large amount of secondary combustion air flows along the inner surface of the can body (21), thereby making it difficult for the combustion exhaust to come into contact with the inner surface and lowering the dew point temperature. Although the condensation on the inner surface of the can body (21) can be prevented, this technique cannot be applied to a heat exchange apparatus in which an all-primary air type gas burner (11) as shown in FIG. 5 is incorporated. On the other hand, in the present invention, since the dew condensation is prevented by judging the temperature of the wound part (34) in the can body (21), it is a combustion apparatus incorporating a gas burner of all primary combustion type. It can be applied regardless of whether it is a Bunsen burner type heat exchange device.
[Brief description of the drawings]
1 is a schematic diagram of a heat exchange device according to an embodiment of the present invention. FIG. 2 is a flowchart for controlling the heat exchange device of FIG. 1. FIG. 3 is a heat exchange device showing another embodiment of the present invention. Fig. 4 is an explanatory diagram of a conventional example. Fig. 5 is an explanatory diagram of an improvement plan of the conventional example.
(2) ... Heat exchanger
(10) ... Air supply fan
(11) ・ ・ ・ Gas burner
(20) ・ ・ ・ Heat exchange part
(21) ・ ・ ・ Can body
(23a) ・ ・ ・ Endothermic tube
(26) ... Bypass pipe
(41) ... Flow ratio setting device
(61) ... Auxiliary heat sink
(63) ... Temperature sensor

Claims (1)

A heat exchanger (20) provided in the can (21) of the heat exchanger (2) heated by the gas burner (11);
An auxiliary heat absorption pipe (61) connected to the downstream end of the heat absorption pipe (23a) constituting the heat exchange section (20) and wound around the outer periphery of the body of the can body (21);
A bypass pipe (26) connecting the downstream flow path of the auxiliary heat absorption pipe (61) and the upstream flow path of the heat absorption pipe (23a);
The flow rate for adjusting the mixing ratio of hot water and cold water from both pipes (61), (26) at the junction (G) of the downstream flow path of the auxiliary heat absorption pipe (61) and the bypass pipe (26) Ratio setting device (41),
A temperature sensor (63) for determining the temperature of the wound part (34) of the can (21) around which the auxiliary heat absorption pipe (61) is wound;
The flow rate ratio setter so that the mixing ratio required to make the temperature of the wound portion (34) of the can body (21) higher than the dew point of the combustion exhaust in the can body (21) can be set. Means for controlling (41) ,
The temperature sensor (63) is provided in the vicinity of the discharge portion of the heat absorption pipe (23a) ,
The heat exchange device , wherein the temperature of the wound portion (34) is regarded as a temperature slightly higher than the temperature detected by the temperature sensor (63) .

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