JP2527643B2 - A method of controlling the amount of water change in a water heat source air conditioning system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a variable water amount control method in a water heat source air conditioning facility using cold / hot water as a heat source for cooling / heating.

[Conventional technology]

Fig. 1 shows a conventional typical water heat source air conditioning system. 1
Is a heat storage tank, and cold water is stored in the heat storage tank 1 during cooling.
Hot water is stored during heating. This cold / hot water is produced by a heat source device. Taking the case of cold water as an example, the hot water in the high temperature tank 2 is sent to the refrigerator 3 by the primary side pump 4, and the cold water obtained is returned to the low temperature tank 5. Done by At that time, a constant amount of cold water is supplied to the refrigerator 3 (the pump water amount is constant), and the outlet water temperature is controlled by the temperature sensor 6.
The capacity of the refrigerator 3 is controlled so that the detected value becomes a set value.

On the secondary side, cold / hot water in the heat storage tank 1 is circulated through the heat exchanger 7 of the air conditioner arranged in the building by the secondary side pump 8. These heat exchangers 7 are water-side heat exchangers when the air conditioner is a heat pump unit, and air-to-water heat exchangers when the air conditioner is a fan coil unit. Taking the cooling operation as an example, the cold water in the low temperature tank 5 is pumped up through the forward pipe 9, passes through each heat exchanger 7, and then is returned to the high temperature tank 2 by the return pipe 10. At that time, in order to perform air conditioning at a required room temperature in each air conditioner, the temperature of the retan air returning to the air conditioner is detected by the temperature sensor 12, and the water flow rate to the heat exchanger 7 is adjusted so that the detected temperature becomes a set value. Is being controlled. This flow rate is controlled by adjusting the opening of the two-way valve 13 attached to the water supply pipe to each heat exchanger 7, and the bypass pipe 14 bypassing the heat exchanger 7 via the three-way valve 15. Is generally installed and the three-way valve 15 is operated.

Even in the case of heating, there is no difference in that the flow rate of hot water to each heat exchanger is controlled so that the temperature of the ethane air becomes a predetermined temperature.

[Problems to be solved by the invention]

As described above, it is a direct and simple method to control the amount of water passing to each heat exchanger 7 so that the temperature of the retan air becomes a predetermined temperature, but it is a time when the air conditioning load is low, such as in the middle period. Alternatively, when the air conditioning load is small depending on the usage condition of the building, the heat consumption for air conditioning decreases, so the heat exchanger 7
The water temperature difference between the inlet and the outlet of is small. As a result, the refrigerator is operated at a partial load because the water temperature to be cooled is low to cool it to the set water temperature. Therefore, there was a problem that the coefficient of performance (COP) of the refrigerator decreased and the amount of electricity per unit of heat produced increased.

It is possible to control the two-way valve 13 so that the temperature difference between the inlet and the outlet of the heat exchanger 7 becomes large (for example, when the load is low, the amount of water to the heat exchanger 7 is reduced). valve
13 becomes throttle resistance, and pump power is consumed unnecessarily. Further, when the three-way valve 15 is operated, the total amount of water passing through the bypass pipe 14 and the heat exchanger 7 is constant, so that it is not possible to expect a reduction in the pumping power, and it is not possible to expect the use of the high temperature difference of the heat source water. .

The present invention aims to solve such a problem.

[Means for solving problems]

The present invention relates to a water heat source air conditioning system in which a heat source water in a heat storage tank is circulated through a heat exchanger of an air conditioner arranged in a building by a pump, and a two-way valve is provided in a water supply pipe line to each heat exchanger. In addition to installing an inlet water temperature sensor that detects the inlet water temperature to each heat exchanger and an outlet water temperature sensor that detects the outlet water temperature, install the inlet water temperature and outlet water temperature of each heat exchanger from the detected values of both temperature sensors. The temperature difference is calculated, the opening of each of the two-way valves is individually controlled so that the calculated value becomes a predetermined set temperature difference, and water is sent by the pump based on the opening information of each two-way valve. The present invention provides a method for controlling the amount of water change in a water heat source air conditioning system, which is characterized in that the amount of water supplied to the entire power system is calculated and the rotation speed of the pump is controlled so as to achieve this amount of water supplied.

[Detailed Description of the Invention]

The contents and effects of the present invention will be specifically described below with reference to the drawings.

FIG. 2 shows an example of the air conditioning equipment according to the present invention. On the primary side, the primary side pump 4 sends a constant amount of water to the refrigerator 3 and the capacity of the refrigerator 3 is controlled so that the outlet water temperature of the refrigerator 3 becomes a set value, as in the conventional case of FIG. 1. Is. In the present invention, since the COP of the refrigerator 3 is controlled to be improved, only the refrigerator is shown as the heat source side device, but in reality, there is a heating device such as a boiler so that the heating operation can be performed. In the cooling operation, the cold water in the low temperature tank 5 is circulated through the heat exchangers 7 of the air conditioners arranged in the building, and the heated water is returned to the high temperature tank 2 as in the conventional case of FIG. is there. At that time, a variable water capacity pump 17 is used as the cold water pumping pump installed in the outward pipe 9.
In the illustrated example, the rotation speed control is performed by the inverter 18.

The heat exchanger 7 of the air conditioner is a water side heat exchanger when the air conditioner is a heat pump unit, and an air-to-water heat exchanger when the air conditioner is a fan coil unit. And the return pipe 10 are connected in parallel. That is, the cold water in the low temperature tank 5 enters each heat exchanger 7 as it is, and the water leaving each heat exchanger 7 directly returns to the high temperature tank 2 without passing through the other heat exchangers 7.

In each air conditioner, the temperature of the retinal air is detected by the temperature sensor 12 as in the case of FIG. 1. However, in FIG. 1, the two-way valve is controlled so that the retane air temperature becomes the set temperature. On the other hand, in Fig. 2, the air flow rate of the air conditioner is controlled. That is, the air supply fan should be set so that the detected value of the temperature sensor 12 becomes constant.
The rotation speed of 19 is controlled by the inverter 20.

Even in the equipment shown in FIG. 2, a two-way valve is provided in the inlet pipe to each heat exchanger 7.
Although 13 is provided, the control of the two-way valve 13 is different from that of FIG. 1 so that the water temperature difference between the outlet and the inlet of the heat exchanger 7 is controlled to a predetermined value. That is, the outlet temperature sensor 21 is provided in the outlet pipe of each heat exchanger 7, and each heat exchanger 7
An inlet temperature sensor 22 for detecting the incoming water temperature is installed, and the two-way valve 13 is controlled so that the detection values of both sensors 21 and 22 have a predetermined magnitude. The inlet temperature sensor 22 is used to detect the cold water temperature common to the heat exchangers 7 in order to detect the cold water temperature in the pump 17 of the forward pipe 9.
It is provided on the discharge side of.

Reference numeral 23 indicates a control computer, and each two-way valve 13
The total amount of water required by the pump 17 for the entire system is calculated from the opening of the pump, and the control opening is commanded to each two-way valve 13, and the rotation speed command is required for the inverter 18 of the pump 17.

 The control operation will be described below.

The control of the present invention is performed by the control routine of the two-way valve 13 and the pump 17
The control routine on the pump side is calculated by the control routine of the two-way valve, and the opening degree of the controlled two-way valve is monitored and processed by interruption performed at predetermined time intervals. The control procedure is shown in FIG.

In the two-way valve control routine, the inlet temperature sensor 22
Then, the temperature difference between the water at the inlet and outlet of each heat exchanger 7 is calculated from the measured value of the outlet temperature sensor 21, and the calculated value is compared with the set temperature difference (a large possible value).
Using the deviation value obtained by comparing this measured value with the set value, PI
The control amount by D (proportional, integral, and derivative) operation is calculated, the opening of each two-way valve is determined, and the opening is adjusted. By repeating this routine, the water temperature difference between the inlet and outlet of each heat exchanger 7 is maintained in a high range close to the set value (the amount of water passing through the heat exchanger 7 varies).

From the average value of the opening of each two-way valve and the average value of the rate of change of the opening, the following fuzzy (FUZZY) theory is used to reduce the pressure loss in the pipeline due to the throttle of the two-way valve. Using the calculated membership function, control to open the opening of the two-way valve as much as possible and control the rotation speed of the pump.

In fuzzy control, the information obtained from the control input, in this example, the relationship between the two-way valve opening e ₁ and the two-way valve opening change rate e ₂ and the control output (manipulated variable) u is as follows. As mentioned above.

If e ₁ is P ₁ ,, e ₂ is P ₂ then u ₁ is P ₀ …… (1) If e ₁ is N ₁ , e ₂ is N ₂ then u ₂ is N ₀ …… (2) However, P is input Label that represents the fuzzy set of N (positive and large) N is the label that represents the fuzzy set of the input (Negative and large) Since there are two preconditions, Max operation, Mi
Although n calculations and the like are possible, in this example, synthesis by arithmetic mean is adopted. That is, W ₁ = {P ₁ (e ₁ ) + P ₂ (e ₂ )} / 2 (3) W ₂ = {N ₁ (e ₁ ) + N ₂ (e ₂ )} / 2 (4) Since the inference is performed based on the two rules as in the expressions (1) and (2), the comprehensive inference result is obtained as follows.

The output result of each two-way valve is u _i0 = (W ₁ · u ₁ + W ₂ · u ₂ ) / (W ₁ + W ₂ ) ... (5) , i is the No. of each two-way valve, and the total inference result (that is, the frequency output result of the inverter 18) is However, a _i is the value of P ₁ at the precondition of the two-way valve opening.

The two-way valve opening e ₁ and the two-way valve opening change rate e ₂ which are fuzzy sets are defined as a membership function, which is shown in FIG. In the figure, N (negative) is a negative label in the direction of squeezing the valve, and P (positve) is a positive label in the direction of opening the valve. The middle of the two labels
It is Z ₀ , and shows a proper label. In the control of this example, the valve opening is 80% and is defined as Z ₀ . The method of this fuzzy inference is illustrated in FIG.

In this way, the frequency output of the inverter 18 of the pump 17 is inferred by calculation from the opening information (average value of opening and opening change) of each two-way valve, and the rotation speed of the pump 17 is controlled based on this. At the same time, the opening degree of each two-way valve is adjusted to be opened as much as possible, and even when the heat load of each air conditioner changes individually, The water temperature difference is maintained at a high set value, while the pump speed is controlled to an appropriate value according to the increase / decrease in the throttling resistance of each two-way valve.

As a result, in the refrigerator 3, the temperature difference between the inlet water temperature and the outlet water temperature is maintained at a high value, and the coefficient of performance is improved, and
Since the conveyance power of the secondary side pump 17 is also reduced, high energy saving operation can be realized. Especially in a system where a large temperature difference can be used (for example, an ice heat storage system), the coefficient of performance of the refrigerator can be greatly improved, and power can be recovered more than the reduction of pumping power.

[Brief description of drawings]

FIG. 1 is an equipment layout system diagram showing a control example of a conventional water heat source air conditioning equipment, FIG. 2 is an equipment layout system diagram showing a control example of a water heat source air conditioning equipment according to the present invention, and FIG. 3 is a fuzzy logic according to the present invention. FIG. 4 is a diagram showing a variable water flow control flow, FIG. 4 is a diagram showing a membership relationship of a fuzzy set, and FIG. 5 is a diagram showing a fuzzy inference method. 1 ... Heat storage tank, 2 ... High temperature tank, 3 ... Refrigerator, 4 ... Primary side pump, 5 ... Low temperature tank, 6 ... Temperature sensor, 7 ... Air conditioner (secondary side) heat exchange Reactor, 9 ... Forward, 10 ... Return, 12 ... Retan Air temperature sensor, 13 ... Two-way valve, 17 ... Variable water pump, 18 ... Inverter attached to pump 17, 19 ... … Air conditioner air supply fan, 20 …… Inverter attached to fan 20, 21 …… Heat exchanger outlet temperature sensor, 22 …… Heat exchanger inlet temperature sensor, 23 …… Control computer.

Claims (1)

(57) [Claims] 1. A water heat source air conditioning system in which heat source water in a heat storage tank is circulated through a heat exchanger of an air conditioner arranged in a building by a pump, and two sides are provided in a water supply pipe line to each heat exchanger. In addition to installing a valve, an inlet water temperature sensor that detects the inlet water temperature to each heat exchanger and an outlet water temperature sensor that detects the outlet water temperature should be provided, and the inlet water temperature and outlet water temperature of each heat exchanger should be determined from the detected values of both temperature sensors. The temperature difference of the two-way valve is individually controlled so that the calculated value becomes a predetermined set temperature difference, and the water is pumped by the pump from the information of the opening degree of each two-way valve. A variable water flow rate control method for a water heat source air conditioning system, characterized in that the water flow rate of the entire system to be obtained is calculated and the pump speed is controlled so as to achieve this water flow rate.