JPH0145005Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a terminal pressure control device for a water-type air conditioner, in particular, a device for controlling the terminal pressure of the cold and hot water inlet side of the air conditioner to the optimum pressure according to fluctuations in the circulation flow rate of the cold and hot water. The present invention relates to an improved terminal pressure control device.

[Background Art] Conventionally, water-type air conditioners that use cold or hot water are well known, and these water-type air conditioners exchange heat with indoor air using cold or hot water (hereinafter referred to as cold and hot water) supplied from the outside. We are conducting optimal air conditioning system.

To supply cold and hot water to such a water-type air conditioner, a predetermined amount of cold and hot water is stored in a heat storage tank in advance, and a circulation system for supplying cold and hot water is used to distribute the cold and hot water between the heat storage tank and the air conditioner. This is done by cycling between

For this reason, in conventional cold/hot water supply circulation systems, the cold/hot water in the heat storage tank is pumped out using a discharge pump, and the cold/hot water thus pumped out is circulated to the heat storage tank via an air conditioner. ing. Furthermore, a return water pressure control section is provided at the end of the cold and hot water circulation path, and the circulating cold and hot water is controlled so that it always flows back from the circulation path to the heat storage tank at a constant return water pressure P _O.

By the way, in order to perform good air conditioning using the cold and hot water supplied in this way, it is necessary to change the terminal pressure P _A of the cold and hot water inlet side of the air conditioner to the pressure loss on the downstream side, that is, It is necessary to set the required minimum terminal pressure P L, which is the sum of the pressure loss P L and the return water pressure P _O , at or above the required minimum terminal pressure P _L.

Here, the required minimum end pressure P _L increases as the circulation flow rate Q of cold and hot water increases, and in order to cope with such fluctuations in the required minimum end pressure P _L , in the conventional cold and hot water supply circulation system. adopts a constant discharge pressure control method or a constant terminal pressure control method.

The constant discharge pressure control method is to control the discharge pressure P _B of the discharge pump to be constant at all times, and the discharge pressure P _B is determined by the difference between the required minimum terminal pressure P _L at the rated flow rate and the pressure loss in the water channel. is set to the value added. In this way, according to this constant discharge pressure control method, the terminal pressure P _A is always controlled to be equal to or higher than the required minimum terminal pressure P _L regardless of fluctuations in the flow rate Q, and good air conditioning can be achieved by the air conditioner. It's on.

However, this constant discharge pressure control method
Although the required minimum pressure P _L of P _A decreases with the flow rate Q, the discharge pressure is always controlled to be constant, so the terminal pressure P _A gradually increases as the flow rate decreases. As a result, according to this constant discharge pressure control method, the required minimum pressure decreases as the flow rate decreases.
There was a drawback that the pressure difference between P _L and the terminal pressure P _A became large, and the energy waste generated when operating the discharge pump became extremely large.

Further, the terminal pressure constant control method controls the discharge pressure P _B of the discharge pump, and controls the terminal pressure _PA of the air conditioner to always be equal to the required minimum pressure _PL at the time of the rated flow rate. As a result, regardless of fluctuations in the flow rate Q, the end pressure P _A is always the minimum required end pressure.
Good air conditioning is performed by the air conditioner by controlling the air conditioner to a level higher than P _L.

However, even with this constant end pressure control method, the end pressure is always set to a constant value regardless of the drop in the required minimum pressure P _L due to a decrease in the flow rate _. This results in an excessive pressure that greatly exceeds the required minimum terminal pressure P _L , resulting in an extremely large waste of energy when operating the discharge pump.

[Purpose of the invention] The present invention was devised in view of these conventional problems, and its purpose is to reduce the terminal pressure to the minimum necessary pressure according to the flow rate of cold and hot water supplied to the air conditioner. An object of the present invention is to provide a terminal pressure control device for a water-type air conditioner that can drive a discharge pump with minimum energy by controlling it.

[Configuration of the invention] In order to achieve the above object, the device of the invention has the following features:
A discharge pump that pumps out cold and hot water from the heat storage tank at a predetermined discharge pressure and circulates it between the heat storage tank and the air conditioner, and a return water pressure control unit that controls the pressure of the circulating cold and hot water to the heat storage tank to be constant. , in a cold/hot water supply circulation system of a water type air conditioner that supplies cold/hot water to an air conditioner, a flow rate sensor that detects the flow rate of the circulating cold/hot water, and a pressure drop in the air conditioner determined from the detected flow rate and the return water pressure. an arithmetic circuit that calculates a required minimum end pressure on the cold and hot water inflow side of the air conditioner based on the added value, and calculates and outputs the discharge pressure of the discharge pump based on the required minimum end pressure and the pressure loss in the water channel determined from the detected flow rate; , a discharge pressure control circuit that controls the discharge pressure of the discharge pump based on the calculated value output from the calculation circuit; It is characterized by controlling the terminal pressure to the minimum necessary.

With the above configuration, according to the present invention, the discharge pump can always be driven with the optimum required minimum power, and as a result, it is possible to reduce energy consumption.

[Example] Next, a preferred example of the present invention will be described based on the drawings.

FIG. 1 shows a preferred embodiment of the device according to the present invention, and the device of the embodiment uses a cold and hot water supply circulation system to supply cold and hot water 12 stored in a heat storage tank 10 to a plurality of cold and hot water supply circulation systems. It is supplied to the air conditioner 14.

In an embodiment, the cold/hot water supply circulation system includes a discharge pump 16 provided at its upstream end.
and a return water pressure control section 18 provided on the downstream end side thereof.
and, including. Then, the cold and hot water 12 in the heat storage tank 10 is pumped up by the discharge pump 16, and the cold and hot water 12 is supplied at a predetermined discharge pressure P _B to the upstream piping 20 connected to each air conditioner 14.

The cold and hot water 12 thus supplied to each air conditioner 14 flows back toward the heat storage tank 10 via the downstream piping 22. At this time, the return water pressure P _O of the cold and hot water 12 directed toward the heat storage tank 10 is always controlled to a constant pressure by the return water pressure control section 18 provided at the downstream end side of the pipe 22.

In the embodiment, the discharge pump 16 is formed by connecting in parallel two constant speed pumps 24 and 26 and an inverter pump 28 whose flow rate can be adjusted. Therefore _, by adjusting the flow rate of the inverter pump 28, the discharge pressure P _B can be arbitrarily controlled.
The pressure is detected by a discharge pressure sensor 30 provided near the discharge port 6. The cold and hot water 12 thus discharged flows through the upstream piping 20 and is distributed and supplied to each air conditioner 14 .

Each air conditioner 14 to which cold and hot water 12 is distributed and supplied in this way is installed in an arbitrary air-conditioned zone, and the flow rate of cold and hot water 12 flowing through each of these air conditioners 14 is set on the downstream side thereof. It is controlled by the flow control valve 32 according to the heat load of the corresponding air-conditioned zone.

Each air conditioner 14 is supplied with cold and hot water 1.
2 and the well-known air, and perform optimal air conditioning for each air-conditioned zone.

The cold and hot water 12 used for heat exchange in each air conditioner 14 in this way joins on the downstream side, flows through the pipe 22, and is returned to the heat storage tank 10 via the return water pressure control unit 18. Ru.

In the embodiment, the return water pressure control unit 18 includes a return water pressure sensor 34 provided at the end side of the pipe 22 to detect the return water pressure P _O , and a pair of return water pressure sensors 34 located downstream of the sensor 34 to control the return water pressure P _O. and a return water pressure control valve 36. The control unit 38 controls the return water pressure control valve 36 so that the return water pressure P _O detected by the return water pressure sensor 34 is always a constant pressure. As a result, the cold and hot water 12 flowing through the pipe 22 is always returned to the heat storage tank 10 with a constant return water pressure _PO .

As described above, according to the device of the embodiment, cold and hot water whose flow rate is controlled according to the required heat load is circulated and supplied to each air conditioner 14 provided in each air-conditioned area. As a result, each air conditioner 14 performs air conditioning for each area to be air conditioned.

Here, the pressure loss Pl in the air conditioner 14 is
Then, in order to perform good air conditioning in each air conditioner 14, as mentioned above, the end pressure P _A on the cold/hot water inlet side of the air conditioner 14 is set to the necessary minimum end pressure P A expressed by the following equation. It is necessary to control the pressure to over _L.

P _L = Pl + P _OHere , the pressure loss Pl in the air conditioner 14 is the flow rate Q of the hot and cold water 12
and therefore the required minimum end pressure
P _L also changes according to the flow rate Q of the cold and hot water 12.

FIG. 2 shows the relationship between the flow rate Q of the circulating cold and hot water 12 and the pressure loss Pl ₁ in the air conditioner 14, that is, the loss Pl that occurs when the cold and hot water 12 passes through the coil section provided in the air conditioner 14. is shown, and the air conditioner 14
The loss Pl within is calculated based on the flow rate Q according to the following formula.

Pl=cQ ^m Here, c and m are constants each determined by the coil section in the air conditioner 14, and in the embodiment, they are approximated by the previous equation m=2 and expressed based on the following equation.

Pl=cQ ² Therefore, if the return water pressure P _O is P _O = b, then the flow rate Q
The required minimum terminal pressure P _L of the air conditioner 14 corresponding to
It is expressed by the following formula.

P _L = Pl + P _O = cQ ² + b...(1) In this example, the pressure loss Pl in the air conditioner shown in FIG. If the air conditioners installed above have the same flow rate Q, the total added pressure loss is:
be the same.

This means that the pressure loss inside the air conditioner is
In the case of multiple (n) air conditioners, Pl becomes Pl ₁ = _o 〓 ⁱ⁼¹ CiQi ² = C ¹ Q ₁ ² + C ₂ Q ₂ ² +... +CnQn ² , where C ₁ ~ C _o is a constant, and in this example, it is the same since all the air conditioners are the same, and Q ₁ to _{Q o} are the flow rates in the air conditioner.

Therefore, Pl ₁ = C _1o 〓 ⁱ⁼¹ Qi ² …(1).

On the other hand, in the case of one large air conditioner, Pl ₂ = CQ ² (2).

This is because a large air conditioner is considered to be a simple combination of multiple (n) air conditioners, so Equation (1)
and (2), Pl ₁ = Pl ₂ .

From the above, it is understood that the pressure loss Pl within the air conditioner is the same depending on the open/closed state of the flow rate control valve 32 of each air conditioner and even when the flow rate is the same.

The characteristic feature of the present invention is that the terminal pressure P _A on the cold/hot water inflow side of the air conditioner 14 is always controlled to the required minimum terminal pressure P _L according to the fluctuation of the circulation flow rate Q of the air conditioner 14, and the discharge pump 16 The objective is to make it possible to drive with minimum energy.

For this reason, the apparatus of the present invention is provided with a flow rate sensor 40 that detects the flow rate of the circulating cold and hot water 12, and in the embodiment, this flow rate sensor 40 is
detects the flow rate of the circulating cold/hot water 12 flowing within the downstream piping 22 and supplies the detection signal to the arithmetic circuit 44 via the converter 42 .

The calculation circuit 44 of the present invention calculates the pressure loss Pl generated in the air conditioner 14 based on the circulating flow rate Q detected in this way, and calculates the pressure loss Pl and the predetermined return water pressure P _O as described above. Add based on the first equation to find the required minimum terminal pressure P _L. and,
In order to control the end pressure P _A on the cold and hot water inlet side of the air conditioner 14 to the required minimum end pressure P _L obtained as described above, the pressure drop Pm generated in the water channel is determined from the detected flow rate Q, and The pressure drop Pm and the required minimum terminal pressure P _L are added to calculate and output the discharge pressure P _B of the discharge pump 16.

FIG. 3 shows a specific configuration of the arithmetic circuit 44 used in the device of this embodiment, and FIG.
6 shows the relationship between the discharge pressure P _B and the flow rate Q.

As is clear from FIG. 4, in order to control the end pressure P _A on the cold/hot water inflow side of the air conditioner 14 to the required minimum end pressure P _L , the discharge pressure P _B of the discharge pump 16 must be adjusted to the required minimum end pressure P _L is the pressure loss in the circulation channel.
It is necessary to set it to a value that includes Pm.

The pressure loss in this circulation waterway is expressed as Pm=aQ ⁿ , where a and n are given as predetermined constants depending on the circulation waterway system. In the embodiment, the pressure loss in the waterway system is approximated by n=2 and determined based on the following equation.

Pm=aQ ² Therefore, in this embodiment, the discharge pressure P _B required to control the end pressure P _A on the cold/hot water inflow side of the air conditioner 14 to the required minimum end pressure P _L is calculated and output based on the following formula. are doing.

P _B =aQ ² +cQ ² +b (2) In order to perform such calculation, the calculation circuit 44 of the embodiment converts the detected flow rate Q input from the converter 42 via the I/V converter 48 into the amplifier 50. , 52 and multipliers 54 and 59, respectively. Multiplier 5
0 outputs aQ based on the detected quantity Q thus supplied, and the other amplifiers 52 output CQ. Then, the multiplier 54 multiplies aQ output from the amplifier 50 and Q output from the I/V converter 48, and outputs aQ ² .

Furthermore, multiplier 59 multiplies cQ output from amplifier 52 and Q output from I/V converter 48, and outputs cQ ² . Adder 56 thus outputs aQ ² , cQ ² from multipliers 54 and 59
and the return water pressure b output from the variable resistor 58 are added based on the second equation to obtain the discharge P _B , and the calculated value P _B is supplied to the discharge pressure control circuit 46.

Then, the discharge pressure control circuit 46 controls the discharge pump 1 based on the value P _B calculated and output in this way.
Control the discharge pressure of 6. In the embodiment, the discharge pressure control circuit 46 compares the calculated value P _B output by the calculation circuit 44 with the discharge pressure detected by the discharge pressure sensor 30, and controls the inverter pump 28 by PID so that the two match. Control.

As described above, according to the device of the present invention, the flow rate sensor 40 detects the change in the flow rate of the circulating cold/hot water 12, and the terminal pressure P _A on the cold/hot water flow side of the air conditioner 14 is determined as the required minimum terminal pressure according to the detected flow rate Q. Since the discharge pressure P _B of the discharge pump 30 is controlled to be P _L , the discharge pump 16 can always be operated at the required minimum discharge pressure according to the circulation flow rate Q of the cold and hot water 12, thereby saving energy consumption. becomes possible.

In particular, according to the device of the present invention, the terminal pressure P _A on the cold/hot water inflow side of the air conditioner 14 is always feedback-controlled based on the flow rate Q detected by the flow sensor 40, so that the terminal pressure P _A can be controlled with high reliability. It becomes possible to control the

FIG. 5 shows the relationship between variable end pressure control performed using the device of the present invention, conventional constant discharge pressure control, and constant end pressure control.
00b is the end pressure due to the end pressure variable control of the present invention.
P _A and discharge pressure P _B are shown at 200a and 200a in the figure.
b indicates the terminal pressure P _A and discharge pressure P _B obtained by conventional constant terminal pressure control, and 300a and 300b in the figure indicate terminal pressure P _A and discharge pressure obtained by conventional constant discharge pressure control.
It shows P _B.

Here, according to the conventional terminal pressure constant control method, the terminal pressure P _A is controlled to be the required minimum terminal pressure P _L max at the rated flow rate, as shown by 200a. Therefore, the discharge pressure P _B is controlled as the sum of the end pressure P _L max and the pressure loss aQ ² in the waterway system along the curve indicated by 200b in the figure. On the other hand, according to the device according to the present invention, the terminal pressure P _A
The discharge pressure P _B of the pump 16 is controlled according to the change in the flow rate Q along the curve shown at 100a in the figure.
As shown by 100b in the figure, can be set lower than the discharge pressure 200b of the constant terminal pressure control method, and it is possible to operate the discharge pump while saving energy by this difference.

In addition, the conventional discharge pressure constant control method
300b in the figure so that the terminal pressure P _A is equal to the required minimum terminal pressure P _L max at the rated flow rate of water.
As shown, the discharge pressure P _B is controlled to a constant value P _B max. Therefore, according to this constant discharge pressure control method, even if the flow rate decreases and the pressure loss in the air conditioner 14 decreases, the discharge pressure P _B will always continue to be controlled to P _B max, so the terminal pressure P _A will be equal to the flow rate. As Q decreases, it increases along the curve 300a in the figure, and the pressure difference with the straight line 100a indicating the required minimum terminal pressure P _L increases.

On the other hand, the device according to the present invention controls its end pressure P _A along the necessary minimum end pressure P _L =cQ ² +b shown at 100a in the figure, so the pressure difference between these two curves 300a and 100a As a result, the energy required to operate the discharge pump 16 can be significantly reduced compared to the conventional _constant discharge pressure control method. becomes.

In this embodiment, the case where the end pressure P _A on the cold/hot water flow rate side of the air conditioner 14 is accurately controlled in accordance with the required minimum end pressure P _L has been described as an example.
The present invention is not limited to this, but it is sufficient to control the end pressure P _A to a value close to the required minimum end pressure P _L ,
For example, as shown by the dashed line in FIG. 4, the necessary minimum terminal pressure is approximated by a straight line, and the terminal pressure P _A on the cold and hot water inflow side of the air conditioner 14 is calculated along the approximate straight line
It is also possible to control

[Effects of the invention] As explained above, according to the invention, in order to always control the terminal pressure on the cold/hot water inflow side of the air conditioner to the optimal required minimum terminal pressure according to the flow rate, the cold/hot water is supplied to the air conditioner. The discharge pump that is driven for supply can always be operated with a minimum discharge pressure, and as a result, the energy required for operating the discharge pump can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a preferred embodiment of the terminal pressure control device for a water-type air conditioner according to the present invention, and FIG. 2 is a characteristic diagram of pressure loss in the air conditioner 14 of the device shown in FIG. 3 is a detailed block diagram of the arithmetic circuit of the device shown in FIG. 1, FIG. 4 is an explanatory diagram of the discharge pressure controlled by the device according to the present invention, and FIG. 5 is a diagram showing the device according to the present invention and the conventional one. It is a characteristic comparison diagram showing the relationship with the device. 10... Heat storage tank, 12... Cold/hot water, 14... Air conditioner, 16... Discharge pump, 18... Return water control unit, 40... Flow rate sensor, 44... Arithmetic circuit, 4
6...Discharge pressure control circuit.

Claims (1)

[Scope of claim for utility model registration] (1) A discharge pump that pumps out cold and hot water from the heat storage tank at a predetermined discharge pressure and circulates it between the heat storage tank and the air conditioner, and a system that maintains a constant pressure of the circulating cold and hot water to the heat storage tank. In a cold/hot water supply circulation system for a water-type air conditioner that supplies cold/hot water to the air conditioner, the system includes: a return water pressure control unit that controls the flow rate of the circulating cold/hot water; Calculate the required minimum end pressure on the cold/hot water inflow side of the air conditioner based on the added value of the pressure loss inside the air conditioner and the return water pressure, and discharge based on the required minimum end pressure and the pressure loss in the waterway determined from the detected flow rate. A calculation circuit that calculates and outputs the discharge pressure of the pump; and a discharge pressure control circuit that controls the discharge pressure of the discharge pump based on the calculation value output from the calculation circuit, and adjusts the end pressure of the cold and hot water inlet side of the air conditioner to the cold temperature. A terminal pressure control device for a water-type air conditioner, which is characterized by controlling the terminal pressure to the optimum required minimum terminal pressure according to fluctuations in the circulating flow rate of water. (2) A terminal pressure control device for a water-type air conditioner, wherein the device according to claim (1) is characterized in that the discharge pressure control circuit performs PID control of the discharge pump based on the output from the arithmetic circuit. .