JP2014040955A - Hot water storage type water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a heat exchange loss in a low supply water temperature.SOLUTION: A hot water storage type water heater includes: a hot water supply outer heat exchanger 3 for heating secondary side flowing water by hot water stored in a hot water storage tank 2 and circulated to the primary side and supplying the heated water; a primary side outgoing pipe 5 for connecting an upper part of the hot water storage tank 2 to a primary side inlet 3a of the hot water supply outer heat exchanger 3; a primary side return pipe 6 for connecting a primary side outlet 3b of the hot water supply outer heat exchanger 3 to the hot water storage tank 2; a primary side pump 7 for circulating hot water in the hot water storage tank 2 to the primary side of the hot water supply outer heat exchanger 3; a water supply pipe 8 connected to a secondary side inlet 3c of the hot water supply outer heat exchanger 3; and a hot water supply pipe 9 connected to a secondary side outlet 3d of the hot water supply outer heat exchanger 3. The hot water supply outer heat exchanger 3 adopts a counter-flow system in which an approximate counter-flow is constituted by a primary side flow direction and a secondary side flow direction and an auxiliary heat exchanger 11 for performing heat exchange between water allowed to flow into the hot water supply outer heat exchanger 3 and primary side hot water allowed to flow out from the hot water supply outer heat exchanger 3 is also installed in addition to the hot water supply outer heat exchanger 3.

Description

  The present invention relates to a hot water storage type hot water heater that circulates hot water in a hot water storage tank to a primary side of a hot water supply external heat exchanger and heats flowing water flowing on a secondary side to supply hot water.

  Conventionally, in a hot water storage type water heater having an external heat exchanger of this type, as in Patent Document 1, a hot water storage tank for storing hot water, a heating means for heating the hot water in the hot water storage tank, and a primary side A hot water supply external heat exchanger that heats and supplies hot water flowing from the hot water in the hot water storage tank circulating through the hot water tank, and a primary side connecting the upper part of the hot water storage tank and the primary inlet of the hot water supply external heat exchanger A side return pipe, a primary return pipe connecting the primary outlet of the hot water supply external heat exchanger and the hot water storage tank, and a hot water in the hot water storage tank provided outside the hot water supply provided in the middle of the primary return pipe. A primary side pump that circulates to the primary side of the heat exchanger, a water supply pipe connected to the secondary side inlet of the hot water supply external heat exchanger, and a hot water supply pipe connected to the secondary side outlet of the hot water supply external heat exchanger There was something with.

JP 2012-107843 A

  However, in such a conventional one, a plate-type heat exchanger is used as an outside hot water supply heat exchanger, and a counter flow system in which the flow direction on the primary side and the flow direction on the secondary side are substantially counter flow is used. However, in the case of a counter-flow heat exchanger that exchanges heat between water, the primary flow rate increases and the primary outlet temperature rises when the feed water temperature is low compared to when the feed water temperature is high. As a result, a heat exchange loss occurs in which the temperature difference between the feed water temperature and the primary outlet temperature increases.

  In addition, in a hot water storage water heater such as a hot water heater that circulates the hot water in the hot water storage tank to the primary side of the hot water external heat exchanger and heats the flowing water flowing on the secondary side to supply hot water, the hot water in the hot water storage tank Since it becomes a heat source for heating the hot water on the secondary side, it is necessary to avoid an increase in hot water having heat that cannot contribute to the heat exchange that occurs due to an increase in the outlet temperature of the primary side.

  Therefore, in order to reduce the heat exchange loss even at a low water supply temperature, it can be solved by increasing the heat capacity of the hot water supply external heat exchanger, but this increases the size of the heat supply external heat exchanger and makes the entire equipment large. There was a problem that it became expensive.

  Therefore, in order to solve the above-described problems, the present invention provides a hot water storage tank for storing hot water, heating means for heating the hot water in the hot water storage tank, and hot water in the hot water storage tank circulating in the primary side as a heat source as a secondary source. A hot water external heat exchanger that heats and supplies hot water to the hot water, a primary forward pipe that connects the upper part of the hot water storage tank and the primary inlet of the hot water external heat exchanger, and a primary side of the hot water external heat exchanger A primary return pipe connecting the outlet and the hot water storage tank; and provided in the middle of either the primary side forward pipe or the primary side return pipe, hot water in the hot water storage tank A primary side pump that circulates to the primary side, a water supply pipe connected to a secondary side inlet of the hot water supply external heat exchanger, and a hot water supply pipe connected to a secondary side outlet of the hot water supply external heat exchanger, The hot water supply external heat exchanger has a flow direction on the primary side and a secondary side. A counter-flow system in which the flow direction is a substantially counter-current flow, in addition to the hot water supply external heat exchanger, water flowing into the hot water supply external heat exchanger and primary hot water flowing out of the hot water supply external heat exchanger An auxiliary heat exchanger for heat exchange was provided.

  Further, the auxiliary heat exchanger is configured by contacting the water supply pipe and the primary return pipe so that heat can be transferred.

  Moreover, the said hot water supply external heat exchanger shall be comprised with the plate type heat exchanger.

  According to the present invention, during hot water supply, the auxiliary heat exchanger exchanges heat between the water flowing into the hot water external heat exchanger and the primary hot water flowing out of the hot water external heat exchanger. Heat that cannot contribute to heat exchange as the temperature of water flowing into the secondary side rises, reducing heat exchange loss in the hot water external heat exchanger, and lowering the temperature of the primary hot water returning to the hot water storage tank It is possible to suppress the generation amount of hot water having water.

  In addition, since the auxiliary heat exchanger has a configuration in which the water supply pipe and the primary return pipe are brought into contact with each other so that heat can be transferred, the above-described effects can be achieved with a simple, compact, and inexpensive auxiliary heat exchanger.

Schematic configuration diagram of one embodiment of the present invention

Next, a hot water storage type water heater according to an embodiment of the present invention will be described with reference to the drawings.
1 is a tank unit having a hot water storage tank 2 for storing hot water, 3 is a hot water external heat exchanger composed of a plate heat exchanger for heating the hot water in the hot water tank 2 as a heat source, and 4 is a hot water tank 2. The primary side circulation circuit 4 circulates the hot water inside the hot water supply outside heat exchanger 3 to the primary side, and the primary side circulation circuit 4 connects the one side inlet 3 a of the hot water supply outside heat exchanger 3 and the upper part of the hot water storage tank 2. The primary side return pipe 5 is composed of a primary side return pipe 6 that connects the primary side outlet 3b of the hot water supply external heat exchanger 3 and the lower part of the hot water storage tank 2, and the upper part of the hot water storage tank 2 is in the middle of the primary side return pipe 6. A primary pump 7 is provided for circulating the hot water taken out from the primary side of the hot water supply external heat exchanger 3.

  8 is a water supply pipe connected to the secondary side inlet 3 c of the hot water supply external heat exchanger 3, and 9 is a hot water supply pipe connecting the secondary side outlet 3 d of the hot water supply external heat exchanger 3 and the hot water tap 10. Here, the water supply pipe 8 is directly connected from the city water to the hot water supply external heat exchanger 3 without going through the pressure reducing valve.

  Here, the hot water supply external heat exchanger 3 is disposed in the tank unit 1 in a posture in which a counter flow type plate heat exchanger in which the flow direction on the primary side and the flow direction on the secondary side are substantially opposite flows is set up. The primary side inlet 3a and the secondary side outlet 3d are arranged at the bottom of the end plate on one side, and the primary side outlet 3b and the secondary side inlet 3c are arranged on the top of the end plate on the same surface. It is what.

  Reference numeral 11 denotes an auxiliary heat exchanger for exchanging heat between the water flowing into the hot water supply external heat exchanger 3 and the primary hot water flowing out of the hot water supply external heat exchanger 3. The primary side upstream of the water supply pipe 8 and the primary pump 7. The return pipe 6 is configured to contact the return pipe 6 over a predetermined length so that the flow direction of the feed water flowing through the feed pipe 8 and the flow direction of the primary hot water flowing through the primary return pipe 6 are opposed to each other. It is what you are doing.

  12 is a heat pump unit as a heating means for heating the hot water in the hot water storage tank 2, 13 is a heating circuit for circulating the hot water in the hot water storage tank 2 to the heat pump unit 12, and this heating circuit 13 is an inlet of the heat pump unit 12. And a heating return pipe 15 connecting the outlet side of the heat pump unit 12 and the upper part of the hot water storage tank 2, and the hot water storage tank is located in the middle of the heating forward pipe 14. 2 A heating circulation pump 17 for circulating hot water taken out from the lower part to the water side of the refrigerant water heat exchanger 16 of the heat pump unit 12 is provided.

  18 is a compressor that compresses the refrigerant, 19 is an expansion valve that decompresses and expands the pressure of the refrigerant, 20 is an evaporator that evaporates the liquid refrigerant, 21 is a blower that blows outside air as a heat source to the evaporator 20, and 22 is refrigerant water An incoming water temperature sensor 23 detects the temperature of hot water from the hot water storage tank 2 flowing into the water side of the heat exchanger 16, and 23 is the temperature of hot water boiled up by the heat pump unit 12 flowing out from the water side of the refrigerant water heat exchanger 16. The boiling temperature sensor 24 detects the outside air temperature, and the outside air temperature sensor 24 detects the outside air temperature. The heat pump unit 12 compresses the refrigerant absorbed by the evaporator 20 by the compressor 18 and supplies water via the refrigerant water heat exchanger 16. It is intended to be heated.

  Reference numeral 25 denotes a heating branch pipe branched from the middle of the heating return pipe 15 and connected to the primary return pipe 6, and 26 is provided at a branch point of the heating return pipe 15 and the heating branch pipe 25 to receive hot water from the heat pump unit 12. This is a heating switching valve that switches between returning to the upper part of the hot water storage tank 2 or returning to the lower part of the hot water storage tank 2 via the heating branch pipe 25 and the primary return pipe 6.

  Reference numeral 27 denotes a supplementary water pipe branched from the hot water supply pipe 9 and connected between the primary pump 7 of the primary return pipe 6 and the connection point of the heating branch pipe 25, and 28 is provided in the middle of the supplementary water pipe 27 to control the supply water pressure. A pressure reducing valve 29 for reducing the pressure is an overpressure relief valve that is connected to the primary side outgoing pipe 5 and releases the overpressure in the hot water storage tank 2.

  30 is a water supply temperature sensor that is provided in the middle of the water supply pipe 8 and detects the temperature of the water supply, 31 is a hot water supply temperature sensor that is provided in the middle of the hot water supply pipe 9 and detects the temperature of the hot water supply, and 32 is a water supply temperature sensor provided in the middle of the hot water supply pipe 9. The hot water supply flow sensor 33 detects the temperature of hot water as a heat source that is provided in the primary side forward pipe 5 and flows into the hot water external heat exchanger 3, and 34 is in the middle of the primary return pipe 6. A primary outlet temperature sensor 35 that detects the temperature of the primary hot water flowing out of the hot water supply external heat exchanger 3 is provided, and a plurality of hot water storage temperature sensors 35 are provided on the upper and lower sides of the hot water storage tank 2 to detect the hot water storage temperature.

  Reference numeral 36 denotes a remote controller including an operation switch for setting a desired hot water supply set temperature and a display unit for displaying the hot water set temperature.

  37 is a water temperature sensor 22, a boiling temperature sensor 23, an outside air temperature sensor 24, a water temperature sensor 30, a hot water temperature sensor 31, a hot water flow sensor 32, a primary inlet temperature sensor 33, a primary outlet temperature sensor 34, and a hot water temperature sensor 35. The detection value is input, and the operation of the primary side pump 7, heat pump unit 12, heating circulation pump 17, compressor 18, expansion valve 19, blower 21, heating switching valve 26 is controlled, and connected to the remote control 36 so as to be communicable. Control means. The control means 37 stores a program for controlling the operation of the water heater in advance, and has a calculation, comparison, storage function, and clock function.

<Boiling operation>
At the start time of a predetermined time zone (midnight time zone) when the power unit price is cheap, the control unit 37 drives the heat pump unit 12 and the heating circulation pump 17 to start boiling the hot water amount corresponding to the hot water supply load amount so far. The hot water taken out from the lower part of the hot water storage tank 2 is started and heated to the set temperature.

  At this time, the control means 37 keeps the heating switching valve 26 on the side of the heating branch pipe 25 while the boiling temperature detected by the boiling temperature sensor 23 is lower than a predetermined temperature lower than the boiling setting temperature, and the temperature is low. When hot water is prevented from flowing in from the upper part of the hot water storage tank 2 to lower the hot water storage temperature and the boiling temperature reaches a predetermined temperature lower than the boiling temperature, the heating switching valve 26 is set to the upper side of the hot water tank 2. The hot water that has been boiled so as to communicate with each other is returned to the upper part of the hot water storage tank 2, and hot water at the boiling set temperature is stored in a stacked manner from the upper part of the hot water storage tank 2.

  When the lowermost hot water storage temperature sensor 35 detects a predetermined boiling end determination temperature, the control unit 37 stops driving the heat pump unit 12 and the heating circulation pump 17 and ends the boiling operation.

  At this time, the hot water stored in the hot water storage tank 2 expands as the temperature of the hot water in the hot water storage tank 2 rises. When the pressure in the hot water storage tank 2 exceeds the set pressure of the overpressure relief valve 29, the overpressure relief valve 29 opens. When the expanded water is drained and the pressure in the hot water storage tank 2 becomes equal to or lower than the set pressure of the overpressure relief valve 29, the overpressure relief valve 29 is closed and the drainage is stopped to keep the hot water tank 2 at an appropriate pressure. Yes.

  Then, the hot water stored in the hot water storage tank 2 contracts due to the natural heat dissipation of the hot water in the hot water storage tank 2 over time and the temperature drop of the hot water in the hot water storage tank 2 due to the hot water supply described later, and the pressure in the hot water storage tank 2 is reduced. When the pressure becomes lower than the set pressure of 28, the city water flows into the hot water storage tank 2 from the supplementary water pipe 26 via the pressure reducing valve 28, and when the pressure in the hot water storage tank 2 becomes equal to or higher than the set pressure of the pressure reducing valve 28, The inflow of water stops and the hot water storage tank 2 is kept in a full water state at an appropriate pressure.

<Hot water supply operation>
Next, the hot water supply operation will be described. When the hot water tap 10 is opened, the city water that has passed through the auxiliary heat exchanger 11 flows from the water supply pipe 8 into the secondary side of the hot water supply external heat exchanger 3 to exchange heat outside the hot water supply. Hot water that has passed through the secondary side of the vessel 3 flows out from the hot water supply pipe 9 toward the hot water tap 10. At this time, when the hot water supply flow sensor 32 detects a predetermined minimum working water amount or more, the control means 37 detects the water supply temperature detected by the water supply temperature sensor 30, the hot water supply set temperature set by the remote controller 36, and the hot water supply flow sensor. The hot water supply required heat amount is calculated from the hot water supply flow rate detected in 32, and the primary side pump 7 is started to drive at a rotational speed corresponding to the hot water storage temperature detected by the hot water storage temperature sensor 35 and the calculated hot water supply required heat amount. .

  Then, the number of revolutions of the primary pump 7 is feedback controlled so that the hot water temperature detected by the hot water temperature sensor 31 matches the hot water set temperature set by the remote controller 36 to supply hot water at the hot water set temperature.

  At this time, in the auxiliary heat exchanger 11, the city water flowing from the water supply pipe 8 and the hot water whose temperature has decreased after heat exchange in the hot water outside heat exchanger 3 returning from the primary return pipe 6 to the hot water storage tank 2 are exchanged. Then, the temperature of the city water flowing into the hot water supply external heat exchanger 3 is raised, and at the same time, the temperature of the primary hot water returning to the hot water storage tank 2 is lowered.

  Therefore, since the temperature of the city water flowing into the secondary side of the hot water supply external heat exchanger 3 is higher than that of the conventional one, the rotational speed of the primary pump 7 is suppressed to be low, and the heat in the hot water supply external heat exchanger 3 The exchange loss is reduced, the temperature of the hot water on the primary side returning to the hot water storage tank 2 is also lowered, the amount of hot water having heat that cannot contribute to the heat exchange can be suppressed, and the heat in the hot water storage tank 2 is effectively used. Can be used.

  Here, the auxiliary heat exchanger 11 contacts the water supply pipe 8 made of the copper pipe in the tank unit 1 and the primary return pipe 6 made of the copper pipe so as to be able to transfer heat over a predetermined length so as not to be separated. Since it is the structure which only restrained with the band, the auxiliary | assistant heat exchanger 11 can be provided almost without changing the occupation space in the tank unit 1 with the hot water storage type water heater of the structure without the conventional auxiliary heat exchanger 11, Simple, compact and inexpensive.

  When the hot water supply flow rate detected by the hot water supply flow rate sensor 32 decreases to less than the minimum working water amount, for example, when the hot water tap 10 is closed, the control unit 37 stops the operation of the primary pump 7 and ends the hot water supply.

<Waiting for hot water supply>
During the hot water supply standby after the hot water supply is stopped, the hot water flowing from the upper part of the hot water storage tank 2 remains in the vicinity of the primary side inlet 3a of the hot water external heat exchanger 3, and the secondary side near the secondary side outlet 3d remains. Although the hot water is heated, the primary side inlet 3a and the secondary side outlet 3d are located in the lower part of the hot water supply external heat exchanger 3, so that hot water near the primary side inlet 3a is not supplied from the hot water supply external heat exchanger 3. The heat is conducted to the hot water on the primary side and the secondary side having a low temperature on the upper side of the hot water, and the specific gravity difference between the hot water on the primary side and the secondary side having a low temperature on the upper side of the hot water supply heat exchanger 3 is also upward. The hot water in the vicinity of the primary side inlet 3a of the hot water supply external heat exchanger 3 quickly drops in temperature, and boiling occurs after the hot water on the secondary side of the hot water supply external heat exchanger 3 is overheated. Absent.

  In this way, since no secondary boiling occurs in the hot water on the secondary side in the hot water supply external heat exchanger 3 during standby for hot water supply, it is possible to prevent the occurrence of overshooting of the hot water temperature at the beginning of the next hot water supply. it can.

  In addition, since the auxiliary heat exchanger 11 has a simple configuration in which the pipes are simply brought into contact with each other so that heat can be transferred, in the state where the flow on both the water supply pipe 8 side and the primary return pipe 6 side is stopped. There is almost no heat exchange, and the hot water supply performance at the beginning of the next hot water supply is not affected.

  The present invention is not limited to the above-described embodiment, and can be modified without changing the gist of the invention. For example, the hot water supply external heat exchanger 3 is preferably a plate heat exchanger, The heat exchanger is not limited to the plate heat exchanger, and may be a counter flow type heat exchanger in which the flow direction on the primary side and the flow direction on the secondary side face each other.

  Further, the heating means is not limited to the heat pump unit 12 and, for example, exhaust heat by cogeneration, solar heat, or an electric heater may be used as the heating means.

2 Hot water storage tank 3 Hot water supply external heat exchanger 3a Primary side inlet 3b Primary side outlet 3c Secondary side inlet 3d Secondary side outlet 5 Primary side forward pipe 6 Primary side return pipe 7 Primary side pump 8 Water supply pipe 9 Hot water supply pipe 11 Auxiliary heat Exchanger 12 Heat pump unit (heating means)

Claims (3)

  Hot water storage tank for storing hot water, heating means for heating the hot water in the hot water storage tank, and hot water outside heat exchange for supplying hot water by heating the running water on the secondary side using the hot water in the hot water tank circulating in the primary side as a heat source A primary side forward pipe connecting the upper part of the hot water storage tank and the primary inlet of the hot water supply external heat exchanger, and a primary return pipe connecting the primary outlet of the hot water supply external heat exchanger and the hot water storage tank A primary-side pump provided in the middle of either the primary-side forward pipe or the primary-side return pipe to circulate hot water in the hot water storage tank to the primary side of the hot-water supply external heat exchanger, and the hot-water supply outside A hot water supply pipe connected to the secondary side inlet of the heat exchanger and a hot water supply pipe connected to the secondary side outlet of the hot water supply external heat exchanger, the hot water supply external heat exchanger is a flow direction on the primary side And the flow direction on the secondary side is a counter flow system in which the flow is almost counter flow. In addition to the hot water supply external heat exchanger, an auxiliary heat exchanger for exchanging heat between the water flowing into the hot water supply external heat exchanger and the primary hot water flowing out of the hot water supply external heat exchanger is provided. Hot water storage water heater.   The hot water storage type hot water heater according to claim 1, wherein the auxiliary heat exchanger is configured by bringing the water supply pipe and the primary return pipe into contact with each other so that heat can be transferred.   The hot water storage type hot water heater according to claim 2, wherein the hot water supply external heat exchanger is constituted by a plate heat exchanger.

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