JP2007132539A - Hot water storage type water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constitution capable of preventing the disadvantageous stirring of hot water in a tank by hot water outputted from a heat exchanger, in a hot water storage type water heater wherein a heat exchanger is connected with a fuel cell, and the hot water heated up by the heat exchanger is circulated into a hot water storage tank in addition to storing hot water heated by a heat pump unit in the hot water storage tank. <P>SOLUTION: In this hot water storage type water heater which comprises an electrically-operated heat pump unit 12 preparing the hot water of a high temperature by heating the water led out of a lower portion in a hot water storage tank 10 and circulating the same to the upper portion of the hot water storage tank, and in which the water led out from the lower portion of the hot water storage tank is further heated by the heat exchanger 33 connected with a fuel cell unit by the exhaust heat of the fuel cell 31, the hot water heated by the heat exchanger 33 is circulated to an intermediate portion Pc in the height direction between the upper portion and the lower portion of the hot water storage tank 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot water storage type hot water supply apparatus that operates a heat pump with electric power and heats water supply until it reaches a target heat storage amount commanded by a control device and stores it in a hot water storage tank, and in particular, a house where a fuel cell is disposed. The present invention relates to an improvement for efficiently using exhaust heat generated by the fuel cell.

  Nowadays, fuel cells have already begun to be used as power generators for home use because of their high power generation efficiency and ease of downsizing compared to other power generators. In general, a fuel cell uses city gas or the like as fuel, and generates electricity by chemically reacting hydrogen in the fuel and oxygen in the air. Such fuel cells generate heat during power generation and when hydrogen is extracted from the fuel. Therefore, it is necessary to provide some kind of exhaust heat means to the fuel cell in order to avoid a reduction in the efficiency of the device.

Therefore, as recognized in the following Patent Document 1 or the like, in order to make reasonable use of this requirement in reverse, a heat exchanger is connected to the fuel cell as an exhaust heat means, and the hot water boiled up by this is stored. There is a technology that attempts to reduce the operating power of the heat pump unit by circulating from the top of the hot water storage tank of the hot water supply system into the hot water storage tank.
JP 2005-76934 A

  However, as can be seen in this conventional example, in the system in which the hot water output from the heat exchanger is unconditionally recirculated to the top of the hot water storage tank, various problems are often caused for the reasons described below.

  Generally, the temperature in the hot water storage tank is high due to the difference in specific gravity between hot water and water, and the temperature of the hot water in the upper part of the tank is high and the temperature of the hot water in the lower part is low. In other words, it is not necessary that the entire hot water storage tank is hot water in order to output hot water at a temperature desired by the user, and only the upper part needs to be sufficiently high. It is enough to do. For this reason, the hot water heated by the heat pump is poured from the upper part of the tank into the tank in order to suppress the stirring of the hot water in the tank as much as possible.

  However, the temperature of hot water heated by the exhaust heat of the fuel cell through the heat exchanger and circulating to the hot water storage tank is generally much lower than the temperature of the hot water stored in the hot water storage tank. Therefore, similar to the hot water from the heat pump unit, when the hot water output from the heat exchanger is circulated or poured from the top of the tank, there is a problem that the hot water in the tank is greatly stirred, and the hot water temperature in the upper part of the hot water storage tank is unsatisfactory. The heat pump unit may be unnecessarily operated even in the daytime.

  In other words, in order to reduce the electricity usage fee, the heat pump unit is usually designed to operate in the midnight power hours when the heat usage fee is low and to avoid operating the heat pump unit during the day. Despite this, this view was sometimes dismissed.

  In addition, regarding the operation of the heat pump unit itself, the conventional apparatus does not consider the heating amount of hot water in the hot water storage tank due to the exhaust heat of the fuel cell with respect to the required heating amount and the required heating time, but simply the amount of hot water per day. Since the heating was performed only based on the amount used, the hot water in the hot water storage tank was often heated more than necessary.

  The present invention has been made for the purpose of solving such disadvantages of the conventional example, and firstly provides a configuration for preventing the above-described inadvertent stirring of the hot water in the tank by the hot water of the heat exchanger output. Therefore, it is desirable to further suppress useless operation of the heat pump.

In order to achieve the above object, the present invention
The water drawn from the lower part of the hot water storage tank is heated to form hot hot water and circulated to the upper part of the hot water storage tank, and the water derived from the lower part of the hot water storage tank by the exhaust heat of the fuel cell is used as the fuel cell unit. In a hot water storage hot water supply system heated by a combined heat exchanger;
Circulating the hot water heated by the heat exchanger to the middle part in the height direction between the upper and lower parts of the hot water storage tank;
We propose a hot water storage type hot water supply device characterized by

  Furthermore, as a desirable lower aspect of the present invention, after satisfying the above configuration, an average temperature rise value per day and a temperature rise value standard deviation of hot water in a hot water storage tank due to exhaust heat generated from the fuel cell in the daytime, Based on the average daily hot water usage and the standard deviation of hot water usage, the hot water storage type has a control device that calculates the necessary minimum heating amount required for the heat pump unit and controls the operation of the heat pump unit to satisfy the calculated value A water heater is also proposed.

  According to the present invention, the hot water heated by the heat exchanger is circulated to the middle part in the height direction between the upper part and the lower part of the hot water storage tank, so that the hot water stored in the hot water storage tank is recirculated. It is possible to suppress the stirring of hot water in the hot water storage tank due to the difference in temperature of the hot water tank, to prevent the temperature of the hot water in the hot water storage tank from being lowered, and ultimately to reduce unnecessary power consumption in the heat pump unit.

  In addition, according to a desirable sub-mode of the present invention, the operation of the heat pump unit can be controlled in consideration of the heated portion of the hot water storage tank due to the exhaust heat generated from the fuel cell in the daytime, so that it is mainly operated at midnight power. The heating amount (operating time) of the set heat pump unit can be minimized, and wasteful power consumption can be suppressed.

  FIG. 1 shows a configuration example of a hot water storage type hot water supply apparatus to which the present invention can be applied. The hot water storage tank 10 is usually made of metal having excellent corrosion resistance (for example, made of stainless steel), and a heat insulating material (not shown) is arranged on the outer peripheral portion, so that hot water for hot water supply can be kept warm for a long time. The shape is generally a vertically long shape, and receives water supply (generally tap water) Wf through a water supply pipe 11 from an inlet provided on the bottom surface.

  The water stored in the hot water storage tank 10 is extracted from the lower part of the hot water storage tank and sent to the power-operated heat pump unit 12 through the supply pipe 13, where it is heated by an existing mechanism, and then from the heat pump unit 12 It is circulated to the upper part of the hot water storage tank 10 via the heat pump output pipe 14 and stored in the hot water storage tank 10.

  Hot water stored in the hot water storage tank 10 and having a high temperature in the upper part is taken out from the upper part of the hot water storage tank 10 through the tank output pipe 16 and sent to the hot water supply mixing valve 17. Water supply Wf is also supplied to the hot water supply mixing valve 17 via the bypass pipe 18, so that the set temperature required by the user at that time is reached by the instruction of the control device 15 that can be configured including a microcomputer in recent years. The mixing ratio of the hot water supply mixing valve 17 is controlled to adjust the actual hot water supply temperature, and the temperature-controlled hot water is output via the hot water supply pipe 19 via the hot water outlet 20 of the faucet, shower, bath, etc. Supplied.

  Of course, various temperature information and actual flow rate information are required to adjust the valve opening of each path of the hot water mixing valve 17, so although not shown in this figure, the water supply pipe 11 is composed of a thermistor or the like. The supplied water temperature detecting means is provided, and the temperature information is output to the control device 15. Although not shown in the figure, the hot water supply pipe 19 is provided with a hot water temperature detecting means 21 which can be constituted by a thermistor or the like, and its temperature information is sent to the control device 15, and the hot water quantity detecting means 21 which can be constituted by a so-called flow counter. The flow rate information from is also sent to the control device 15.

  Further, generally, a plurality of (seven in this embodiment) water level thermistors are arranged on the outer wall surface of the hot water storage tank 11 at substantially equal intervals in the vertical direction (the height direction of the hot water storage tank 11). The temperature information at each water level of the water (hot water) filled in the hot water storage tank 11 is also output to the control device 15. Therefore, the control device 15 can detect, based on the temperature information from each water level thermistor, if the boundary position between the hot water heated up in the hot water storage tank 11 and the water before the hot water in the hot water storage tank 11 is heated up is also required. Among these water level thermistors, the water level thermistor 22a provided at the top is a water temperature (hot water temperature) in the vicinity of the top of the hot water storage tank 11, which is the temperature of the hot water output from the hot water storage tank 10 to the outside. It also has the function of a tank output hot water temperature detection sensor for detecting In addition, generally, a piping system for heating or the like is also connected, but these are omitted because they are not directly related to the present invention.

  In addition to the information on the hot water flow from each of the thermistors and flow rate counters described so far, the control device 15 is supplied from an outside air temperature thermistor (not shown) which is an outside air temperature detecting means provided in the heat pump unit 12 or the like. In addition, based on a signal from an operation switch provided on an operation panel (not shown) such as a remote controller unit (not shown) provided in the kitchen or bathroom, the heat pump unit 12 and The hot water mixing valve 17 is configured to be controlled.

  The most basic function of the control device 15 is that when the hot water detection means 21 detects the flow of water (hot water) in the hot water supply pipe 19, it means that the user has started using hot water through the hot water outlet 20. Therefore, as already described, when this state is satisfied, according to the set temperature set by the user at that time, based on each temperature information described above, the opening area ratio control of the hot water supply mixing valve 17 is performed, The hot water having a temperature as close as possible to the set temperature is discharged from the tap 20.

  On the other hand, a fuel cell unit 31 to which, for example, gas Gs is supplied as fuel is also linked to the hot water storage type hot water supply apparatus, and the generated electric power Ew is an appropriate electric power output terminal as schematically indicated by an outlet symbol. Provided for the user through 32. The fuel cell unit 31 incorporates a heat exchanger 33 for exhausting (absorbing) heat generated by power generation. The heat exchanger 33 is connected with a lead-out pipe 34 from the lower part of the hot water storage tank 10. A relatively low temperature water (hot water) is supplied through the air.

  Hot water heated by the heat exchanger 33 is circulated into the hot water storage tank 10 via the heat exchanger output pipe 35, but the position of the recirculation is important. At the mid-abdominal position Pc in the height direction, the circulation is performed.

  By doing in this way, the hot water stored in the hot water storage tank 10 and the hot water that had been a problem when the hot water was recirculated to the upper part (top) of the hot water storage tank 10 as in the past. Stirring of hot water in the hot water storage tank 10 due to a temperature difference can be suppressed, and the temperature drop of the hot water connected to the hot water supply pipe 19 can be suppressed, so that control is stabilized and, in the end, useless operation of the heat pump can be suppressed. it can.

  In addition, the setting of the mid-abdominal part position Pc can be determined to a site that is considered to be optimal based on empirically standard use conditions in the state before leaving the factory.

  In addition to the excellent configuration of the present invention, the following configuration can be proposed. If it demonstrates, the electric power generation by the fuel cell unit 31 is also implemented in the daytime, so that the hot water temperature in the hot water storage tank 10 continues to be heated. Conventionally, the temperature rise due to this is not taken into account, and for that reason, wasteful power may be consumed for the operation of the heat pump unit 12 at midnight power.

  Therefore, in order to solve such a problem, the rise in the hot water temperature in the hot water storage tank 10 due to the exhaust heat of the fuel cell unit 31 is measured by the hot water temperature monitoring device 22 in the tank in the daytime, and this is transmitted to the control device 15. The average temperature rise value and the temperature rise standard deviation per day are calculated and stored. Further, the hot water supply amount per day is measured via the hot water detection means 21, and this is also transmitted to the control device 15 to calculate and store the average hot water use amount and hot water use standard deviation per day.

  In addition, if calculation is performed based on the average temperature rise value and temperature rise value standard deviation by the fuel cell unit 31, and the average hot water use amount and hot water use amount standard deviation monitored by the hot water amount monitoring device 9, The minimum required heating amount for boiling increase by the heat pump unit 12 necessary to satisfy the target heat storage amount in the hot water storage tank can be calculated without waste, and based on this, the operation of the heat pump to satisfy the calculated value If you control, you get reasonable results. For example, since the control device 15 can stop the heat pump unit 12 only by increasing the required minimum amount, the operation time of the heat pump 12 in the midnight time zone can be rationally reduced, and the power consumption can be kept low.

It is a schematic block diagram of one Embodiment of the hot water storage type hot water supply apparatus which concerns on this invention.

Explanation of symbols

10 Hot water storage tank
12 Heat pump unit
15 Control unit
17 Hot water mixing valve
20 Outlet
21 Hot water detection method
22 Tank temperature monitoring device
31 Fuel cell unit
33 Heat exchanger
Pc Hot water storage tank mid-abdomen position

Claims (2)

The water drawn from the lower part of the hot water storage tank is heated to form hot hot water and circulated to the upper part of the hot water storage tank, and the water derived from the lower part of the hot water storage tank by the exhaust heat of the fuel cell is used as the fuel cell unit. In a hot water storage hot water supply system heated by a combined heat exchanger;
Circulating the hot water heated by the heat exchanger to the middle part in the height direction between the upper part and the lower part of the hot water storage tank;
Hot water storage type hot water supply device characterized by The hot water storage type hot water supply device according to claim 1,
Based on the average daily temperature rise value and temperature rise standard deviation of hot water in the hot water storage tank due to exhaust heat generated from the fuel cell in the daytime, and average daily hot water use amount and hot water use standard deviation Having a control device that calculates the required minimum heating amount required for the heat pump unit and controls the operation of the heat pump unit so as to satisfy the calculated value;
Hot water storage type hot water supply device characterized by