JPH0289946A - Heat storage type heat pump system - Google Patents

Abstract

PURPOSE:To enable cooling and heating to be stably controlled by changing over operation modes, which are objects of control, depending upon the magnitude of a heat load, while compensating the operation of a heat pump whose ability is hardly exhibited in the start of operation, with the function of a heat storage tank. CONSTITUTION:In a first operation mode, the heat-exchanging of brine is carried out with a heat storage tank 2 alone, and cooling and heating are effected to a heat load 4 through water. In a second operation mode, the heat-exchanging of the brine is carried out with both of the heat storage tank 2 and a heat pump 1 operated in the output less than 100%, and the cooling and heating are effected to the heat load 4 through the water. In a third operation mode, the heat-exchanging of the brine is carried out with both of the heat storage tank 2 and the heat pump 1 operated in the output of 100%, and the cooling and heating are effected to the heat load 4 through the water. At the start of operation, a control means 6 once operates in the third operation mode and, in the case where the heat load 4 is lower than the ability of the heat pump 1, the control means 6 changes over the operation in the third operation mode to that in the first operation mode and then changes over the operation in the first operation mode to those in the second and third operation modes when the temperature of the brine at the outlet of the heat storage tank 2 indicates an increase in the heat load 4. On the other hand, in the case where the heat load is great after starting the operation, the control means 6 controls to change over the operation in the third operation mode to those in the second and first operation modes to the extent wherein the difference between the temperatures of water at the inlet and outlet ports 4a of a heat exchanger for the heat load becomes smaller.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a first heat medium circulation path that connects a heat pump, a heat storage tank, and a heat load heat exchanger in series, and
The regenerative heat pump system has a second heat medium circulation path that circulates between the heat exchanger for heat load and the heat load, and more specifically, the heat pump system uses heat stored in a heat storage tank by nighttime electricity for use in daytime air conditioning. The present invention relates to a heat storage heat pump system that can supply heat to a load and reduce the running cost of the heat pump system.

[Conventional technology]

In the above-mentioned regenerative heat pump system,
While operating only the heat storage tank, if the heat load becomes large, it is necessary to switch the operation mode such as operating the heat pump at the same time, but conventionally, the state of the heat load is determined from the temperature difference at the entrance and exit of the heat storage tank and the flow rate. The driving method was decided based on this assumption.

[Problem to be solved by the invention]

However, since the heat load is evaluated using a calorimeter-type measuring instrument, with the temperature difference at the inlet and outlet of the heat storage tank and the flow rate being controlled, it was undeniable that there was room for improvement in terms of cost.

An object of the present invention is to provide a simple measuring device for measuring a controlled object, while still being able to perform rational operation control.

[Means to solve the problem]

A characteristic configuration according to the present invention includes a first operation mode in which only the heat storage tank and the first heat medium exchange heat, and the heat load is cooled/heated via the second heat medium; 1
a second operation mode in which the first heat medium is heat exchanged with the heat pump operated at an output of less than 00% and the heat load is cooled and heated via the second heat medium; and the heat storage tank. setting a third operation mode in which the first heat medium is exchanged with the heat pump operated at 100% output to perform cooling/heating on the heat load via the second heat medium;
When starting the operation, first operate in the third operation mode,
When the heat load is smaller than the beat pump capacity, the operation is switched to the first operation mode, and when the first heat medium temperature at the outlet of the heat storage tank indicates an increase in the heat load, the operation is switched to the first operation mode. Switch to 2 operation mode and 3rd operation mode,
If the heat load is large after the start of operation, the control means controls switching between the second operation mode and the first operation mode as the second heat medium temperature difference at the inlet and outlet of the heat load heat exchanger becomes smaller. In other words, ■ The third operation mode is used at the start of operation, and ■ Depending on the magnitude of the heat load, if the load is small, the temperature of the first heat medium at the outlet of the heat storage tank is controlled. and when the load is large, the temperature of the second heat medium at the inlet and outlet of the heat exchanger for heat load is to be controlled, and the effects are as follows.

[For production]

■ At the start of operation, the third operation mode (thermal storage tank and
% capacity heat pump) at full capacity operation.
Let's explore the compatibility with the heat load. Alternatively, try finding the heat load in the second operation mode.

◎ Then, for example, as shown in the circuit of FIG. 1, a change appears depending on the smoothness of the thermal load (4). In other words, the first
As shown in the figure, the heat storage tank (
A bypass path (10) is provided to bypass the first heat medium circulation path (3).
) is provided at the connection point with the heat pump (12), and if the first heat medium temperature (measured by the temperature sensor (13) in the figure) at the heat pump population is outside the set temperature, only the heat pump (1) The three-way valve (12) is switched to the bypass passage (10) flow side so as to operate the valve.

Therefore, by capturing the switching of the three-way valve (12) like this,
The purpose is to judge the heat load, and after starting operation in the third operation mode or the second operation mode, the three-way valve (12)
is switched to the bypass path (10) side, the heat load (
4) was determined to be below the capacity of heat pump (1). Of course, a method may be adopted in which the operation is started in the third operation mode and the state of the heat load is determined based on the detection result of the temperature sensor for the heat load. There are various possibilities.

As shown in the θ 0 term, once the state of the heat load is known, the following control target is switched depending on its magnitude.

In other words, if the heat load is determined to be less than the heat pump capacity,
The operation mode is switched to the first operation mode to optimize the heat balance with the heat load and to make effective use of heat storage. Then, the operating state after switching to the first operating mode is controlled using the first heat medium temperature on the outlet side of the heat storage tank as a control target.

In this case, the temperature of the second heat medium at the inlet/outlet of the heat exchanger for heat load, which allows the state of the heat load to be known more directly, can be controlled, but since the heat load is small, the second heat medium temperature can be controlled.
The temperature of the heating medium fluctuates rapidly, which makes the control unstable. Instead, stable control is achieved by controlling the first heating medium, which follows thermal load fluctuations more gently than the second heating medium. I decided to do it.

In addition, when the heat load is large, the temperature fluctuation of the second heat medium is relatively gentle, so the heat load state of the second heat medium can be directly known compared to the first heat medium. The temperature difference between the inlet and outlet of the load heat exchanger was controlled.

〔Effect of the invention〕

Therefore, while simultaneous operation with a heat storage tank eliminates the shortcomings of heat pumps, which cannot produce sufficient capacity at startup because refrigerant accumulates on the low-pressure side at the start of operation, switching the control target depending on the size of the heat load makes it possible to Stable heating and cooling control can be performed.

〔Example〕

This regenerative heat pump system is a heat pump (1
), heat exchanger for heat load (4A) as heat load (4),
A brine circulation path (3) is provided as a first heat medium that connects the heat storage tank (2) in series, and a second brine circulation path that circulates between the heat load (4) and the heat load heat exchanger (4A) is provided. It is configured by providing a water circulation path (8) as a heat medium.

The heat pump (1) includes an expansion valve (1d) and an evaporator (1).
a), a compressor (1b), and a condenser (IC), and the brine is heated by the condenser (IC). The heat storage tank (2) is divided into four tanks (2a),
(2b), (2c), and (2d), with the first tank (2a) shown as a thermal heat storage tank and the other three tanks (2b) as shown in the figure.
).

(2c) and (2d) are configured as a cold heat storage tank to provide a cooling-oriented heat storage form that can be used for cooling buildings that require air conditioning even in winter.

The brine circulation path (3) is provided with a first bypass path (9) that bypasses the heat load heat exchanger (4A) and a second bypass path (10) that bypasses the heat storage tank (2). If only heat storage is performed at night, a method may be adopted in which brine is circulated through the first bypass path (9). Further, a first temperature sensor (7) for detecting the brine temperature (Ta) is installed on the outlet side of the heat storage tank (2) of the brine circulation path (3) and the heat load heat exchanger (4A) of the water circulation path (8). ) A second temperature sensor (11) that detects the water temperature ('ra) on the outlet side, and the heat load heat exchanger (4A
) A third temperature sensor (5) for detecting the water temperature ('ro') on the population side is provided, and these sensors (5), (7)
, (11), the brine temperature (T
A control means (6) with a built-in computer is provided to control the heat pump (1) and other electromagnetic valves, etc., with the inlet and outlet water temperature difference ΔT = To Too as control targets.

The second bypass path (10) and the brine circulation path (3)
A three-way valve (12) is provided at the intersection with the brine circulation path (3), and the brine can be circulated through the second bypass path (10). A sensor (13) is provided, and when this fourth temperature sensor (13) detects the set temperature (7° C.), the three-way valve (12) is switched to switch to operation of only the heat pump (1). Therefore, the three-way valve (1
2) is provided with a contact point for sensing whether the brine (13) is switched to a short-circuited state from the second bypass path (10).

Next, the mode of operation control during cooling will be explained. First, there are three types of operation modes. In the first operation mode, only the heat storage tank (2) is used to cool the brine, and the heat pump (1) is stopped.

In the second operation mode, the heat pump (1) is operated together with the heat storage tank (2) at 50% capacity to cool the brine. Here, 50% capacity refers to a capacity control mode in which the compressor is operated with the number of actually operating cylinders halved.

In the third operation mode, the heat pump (1) is operated together with the heat storage tank (2) at 100% capacity to cool the brine.

Therefore, the brine that has absorbed heat from the heat load (4) is stored in the heat storage tank (
2) and the condenser (IC) to increase the cooling capacity.

Cooling control will be explained based on the above three operation modes and with reference to the flow chart in FIG. 2.

First, the start of operation is performed in the third operation mode.

After the start of operation, the three-way valve (12) is connected to the second bypass path (10
), if a signal (tank bypass) is received from the three-way valve (12) contact indicating that the brine has been switched to short-circuit and bypass, it is determined that the heat load is less than the heat pump capacity, and the first operation mode is activated. Switch to In this case, since the heat load (4) is small, temperature control is performed using the brine temperature (To) on the outlet side of the heat storage tank (2).

In this first operation mode, the brine temperature (TB) is 4°C.
If it is above, it is determined that the load has increased, and the mode is switched to the second operation mode, and if the brine temperature (TB) is less than 4°C, the brine temperature (TB) is checked sequentially for 3 hours,
If the temperature is 2° C. or higher, it switches to the second operation mode, and otherwise it maintains the first operation mode. Here, the brine temperature (TI,) is checked after 3 hours have elapsed because the capacity of the heat storage tank (2) is set to correspond to a maximum of 6 hours of continuous operation. Furthermore, even in the second operation mode, if the brine temperature (TB) becomes 7°C or higher, the third operation mode is activated.
Switch to operation mode (step ■).

On the other hand, if the three-way valve (12) had not been switched in the third operation mode, the heat load (4) would have been large, and the
After the heat load has stabilized after a few minutes have elapsed, if the temperature difference (ΔT) between the inlet and outlet of the heat exchanger for heat load (4A) is 4.5° C. or less, it is determined that the cooling is too much and the mode is switched to the second operation mode; 4. 5℃
If the temperature exceeds the temperature, the third operation mode is maintained. or,
The brine temperature ('
If ra) is 2.5℃ or higher, return to the third operation mode,
If the brine temperature (TB) does not reach 2.5°C,
If the inlet/outlet temperature difference (ΔT) is 5.5°C or more, it is assumed that the heat load is large and the mode is switched to the third operation mode, and if it does not reach 5.5°C, the second operation mode is maintained (step 2).

[Another example]

■ In the above example, only the case of cooling was described, but
When performing heating, operation is started in the third operation mode, and the magnitude of the heat load is determined based on the switching state of the three-way valve (12), and if the heat load (4) is small, the brine temperature (TB) is The operation mode is switched by
If ΔT is large, a configuration may be adopted in which the operation mode is switched based on the temperature difference between the inlet and outlet (ΔT).

■ Also, the operation mode switching operation etc. may be performed manually.

(2) The brine temperature (TB) and the like required for switching the operation mode can be arbitrarily selected and are not limited to those in the above embodiments.

- As the first and second heat carriers, various materials such as brine, factory hot water, well water, etc. can be used.

■ Inverter control may be used to control the capacity of the compressor.

■ The second operation mode may be used when starting the operation.

(2) Further, as the control mode, a combination of the first operation mode and the second operation mode, or the first operation mode and the third operation mode may be adopted.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the regenerative heat pump system according to the present invention, and FIG. 1 is an overall configuration diagram, and FIG. 2 is a flowchart diagram. (1)・・・Heat pump, (2)・・・・・・
Heat storage tank, (3)...First heat medium circulation path, (4
)... Heat load, (4a)... Heat exchanger for heat load.

Claims (1)

[Claims] A first heat medium circulation path (3) connecting a heat pump (1), a heat storage tank (2), and a heat load heat exchanger (4A) in series.
and a second heat medium circulation path (8) for circulating the heat load heat exchanger (4A) and the heat load (4), wherein only the heat storage tank (2) is provided. and the first heat medium to exchange heat, and the second heat medium
A first device that cools/heats the thermal load (4) via a heat medium.
In the operation mode, the first heat medium is exchanged between the heat storage tank (2) and the heat pump (1) operated at an output of less than 100%, and the heat load (
4), a second operation mode in which cooling/heating is applied to the heat storage tank (
2) and the heat pump (1) operated at 100% output.
) and a third operation mode in which the first heat medium is subjected to heat exchange and the heat load (4) is cooled/heated via the second heat medium. 3 operation mode or the second operation mode, and the heat load (4)
is smaller than the heat pump (1) capacity, the operation is switched to the first operation mode, and the heat storage tank (2)
The first heat medium temperature (T_B) at the outlet is equal to the heat load (
4), the switch will switch to the second and third operation modes, and if the heat load (4) is large after the start of operation, the heat exchanger for heat load (4A) will be switched to the inlet/outlet. A control means (6) that controls switching between the second operation mode and the first operation mode as the second heat medium temperature difference (Δt) becomes smaller.
) is a regenerative heat pump system.