JPS6232385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an absorption type water chiller/heater, and particularly to a control device suitable for controlling the temperature of cold water or hot water.

Generally, the temperature of cold water or hot water in an absorption type water cooler/heater is controlled by turning on/off the heating source so as to maintain the temperature of the cold water or hot water at a predetermined set value. Specifically speaking, the method for controlling the chilled water temperature is to start heating the heating source when the chilled water outlet temperature reaches a predetermined temperature to turn on the heating source, and to start heating when the temperature reaches the point at which the heating source is turned off. stop. Thereafter, by repeating this on-off operation, the cold water temperature is controlled between the on-temperature and the off-temperature of the heating source. The control policy for hot water temperature is also similar to this.

However, since an absorption type water chiller/heater contains a large amount of refrigerant in solution, it has the characteristic that the temperature of cold water or hot water does not change immediately even when the heating source is turned on or off. Therefore, if the cold water or hot water setting value remains constant as in conventional on/off control, there is a risk that it will not be able to follow the sudden change in the load. There is. For this reason, the cold water or hot water temperature deviates from the set value and the amount of overshoot increases, resulting in not only poor temperature control accuracy but also excess energy corresponding to overshoot.

The present invention has been made based on the above-mentioned matters, and aims not only to precisely control the temperature of cold water or hot water in response to sudden changes in load, but also to prevent excess energy consumption. It is something.

The feature of the present invention is that in an absorption type water cooler/heater that controls the temperature of cold water or hot water to a set value by on/off controlling the heating source of the absorption type water cooler/heater, the cold water or hot water when the heating source is turned off is The setting value for turning on the heating source is corrected according to the rate of temperature change or the rate of load change, and the setting value for turning off the heating source is corrected according to the rate of temperature change of cold or hot water or the rate of load change when the heating source is turned on. It is equipped with a control section that controls the

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a system diagram of an absorption type water chiller/heater equipped with an example of the control device of the present invention. The cold/hot water machine F includes a generator 2 that heats a dilute solution using a heating medium heated by a heating source 1 to generate refrigerant vapor (steam), and a generator 2 that generates refrigerant vapor (steam) by the generator 2 and sends the refrigerant vapor generated by the generator 2 into a cooling water pipe 3. A condenser 4 is cooled and liquefied by the cooling water passing through the condenser 4, and the liquefied refrigerant liquid is evaporated in the condenser 4, and the latent heat of vaporization at that time is taken away from the water flowing in the cold water pipe 5 to generate cold water (cold power). Evaporator 6
A dilute solution is generated by absorbing the refrigerant vapor evaporated in the evaporator 6 into the concentrated solution introduced from the generator 2 while being cooled by the cooling water flowing through the refrigerant circulation pump 7 and the cooling water pipe 3 of the evaporator 6. absorber 8 and absorber 8
A solution pump 9 pumps the dilute solution produced in the generator 2, a high temperature concentrated solution returned from the generator 2 to the absorber 8, and a low temperature dilute solution supplied from the absorber 8 to the generator Heat exchanger 1 that transfers heat between
It is composed of 0. 11 and 12 are cold water pipes 5
13 is a fan coil unit that serves as a load for the water chiller/heater F; 14
In order to control the cold water temperature to a predetermined temperature based on the detection signals from the temperature detectors 11 and 12,
This is a control device that controls the heating source 1.

FIGS. 2 and 3 are time charts illustrating a control method of an example of the control device of the present invention. Of these, FIG. 2 shows a method of correcting the set value according to the rate of change in cold water temperature or the rate of change in load when the heating source 1 is turned off. To determine the rate of change in temperature or load, the heating source off temperature T _pF
Between _F and the on-temperature T _pN , the rate of change detection temperature T _ME
decide. From the chilled water temperatures T ₀ and T ₁ at two times separated by an appropriate time interval Δt when the chilled water temperature passes this temperature T _ME , the rate of change dT of the chilled water temperature can be calculated using the following approximate formula. can.

dT=T ₀ −T ₁ /Δt ...(1) Also, the load Q ₀ at two times with an appropriate time interval Δt when the chilled water temperature passes through T _ME
From and Q ₁ , the load change rate dQ can be calculated by the following approximate formula:
can be found. The time interval Δt is determined depending on equipment conditions and operating conditions.

dQ=Q ₀ −Q ₁ /Δt (2) Here, when using the load change rate, it is convenient to calculate the load from the temperature difference between the inlet temperature and outlet temperature of the cold water and the flow rate of the cold water. Chilled water flow rate can be detected by using a flow meter. Therefore, the load can also be seen as the output of the chilled/hot water unit. The temperature T _ON at which the heating source is turned on is corrected by using the rate of change dT of the chilled water temperature and the rate of change dQ of the load obtained from equations (1) and (2) as shown in the following equation. The subsequent on-temperature T _ON ' of the heating source can be determined.

T _ON =T _ON −K ₁ ·dT−K ₂ ·dQ (3) Here, K ₁ and K ₂ are coefficients that determine the degree of correction regarding each rate of change. This value is determined depending on equipment conditions and operating conditions. However, T _ON ′
is limited to the following ranges:

T _ME T _ON 'T _ON ...(4) If the temperature T _ON at which the heating source is turned on is corrected according to equation (3), if the rate of change dT of the chilled water temperature or the rate of change dQ of the load is large, that is, the chilled water temperature If the load suddenly increases and the load increases, the heating source will be turned on earlier than usual by t _R as shown in FIG.

Therefore, an upward overshoot in the cold water temperature that is expected to occur when the cold water temperature suddenly rises and the load increases can be suppressed. Therefore, it is preferable to use the fan coil unit 13 or the like because it can compensate for the poor start-up characteristics of the absorption type water chiller/heater and accurately control the chilled water temperature to a set value.

Next, FIG. 3 shows a method of correcting the set value according to the rate of change dT of the cold water temperature or the rate of change dQ of the load when the heating source 1 is turned on. Similarly to Figure 2, the rate of change in chilled water temperature or load dT, dQ
In order to find the change rate detection temperature T _ME ' between T _OFF and T _ON . The cold water temperature is this temperature T _M
When passing _E ', find the rate of change in temperature dT and the rate of change in load dQ. From this, the temperature T _OFF at which the heating source is turned off is corrected as shown in the following equation, and the corrected heating source off temperature T _OFF ' is determined.

T _OFF ′=T _OFF −K ₃ ·dT−K ₄ ·dQ (5) Here, K ₃ and K ₄ are coefficients that determine the degree of correction regarding each rate of change. This value is determined depending on equipment conditions and operating conditions. However, T _OF
F ' is limited to the following range:

T _ME ′＞T _OFF ／＞T _OFF ...(6) If the temperature T _OFF at which the heating source is turned off is corrected according to equation (5), if the rate of change in chilled water temperature dT or the rate of change in load dQ is large, That is, if the cold water temperature suddenly drops and the load decreases, the heating source will be turned off earlier than usual by ts, as shown in FIG. Therefore, it is possible to suppress the downward overshoot of the cold water temperature that is expected to occur when the cold water temperature suddenly drops and the load decreases. Therefore, by effectively utilizing the refrigeration output generated from the heat stored inside the absorption water chiller/heater, the chilled water temperature can be precisely controlled to the set value, saving heating sources. This will save energy.

In the embodiment of the present invention described above, each rate of change is determined by the state quantity when the chilled water temperature reaches the change rate detection temperature T _ME or T _ME , but the average rate of change within a certain period of time is You may also ask for Also, (3)
The equation for determining the corrected temperature shown in equation (5) is not limited to this, and for example, only one of the rate of change dT of the cold water temperature or the rate of change dQ of the load may be used. In this embodiment, the case where the outlet temperature of cold water is controlled to a set value has been explained.
The same applies to the case where the cold water inlet temperature is controlled to a set value. In either case, it is preferable to use the rate of change in the inlet temperature of the chilled water as the rate of change in the chilled water temperature because it is easier to deal with increases and decreases in the load. Furthermore, although the present embodiment has been described for the case where cold water is produced, similar control can be performed when hot water is produced by a heat pump.

As detailed above, according to the present invention, the setting value for turning on and off the heating source can be corrected according to the rate of change in cold water or hot water temperature or the rate of change in load, so even if the load changes suddenly, the temperature of cold water or hot water It is possible not only to accurately control the set value, but also to suppress excess energy consumption.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an absorption chiller equipped with an embodiment of the control device of the present invention, and Figs. 2 and 3 illustrate changes in chilled water temperature settings during on/off control in the control device of the present invention. It is a characteristic diagram. 1...Heating source, 2...Generator, 3...Cooling water pipe, 4...
Condenser, 5... Cold water pipe, 6... Evaporator, 7... Refrigerant circulation pump, 8... Absorber, 11... Chilled water outlet temperature detector, 12... Chilled water inlet temperature detector, 13... Fan coil unit, 14 …Control device.

Claims (1)

[Scope of Claims] 1. A control device for an absorption type water cooler/heater having a control unit that controls the temperature of cold water or hot water (cold/hot water) to a set value by on/off controlling a heating source of the absorption type water cooler/heater, comprising: The unit is configured to detect a first rate of change in temperature of the cold/hot water or a first rate of load change when the heating source is turned off, with the temperature of the cold/hot water set between a heating source OFF temperature and a heating source ON temperature. correct the set value of the on-temperature so as to turn on the heating source earlier in proportion to the magnitude of the first temperature change rate or the first load change rate; A second temperature change rate or a second load change rate of the cold/hot water during the on-time is determined when the cold/hot water temperature passes a second change rate detection temperature set between the on-temperature and the off-temperature. and correcting the set value of the OFF temperature so as to turn off the heating source early in proportion to the magnitude of the second temperature change rate or the second load change rate, and correcting the set value of the ON temperature. and a control device for an absorption type water chiller/heater, characterized in that the on/off control is performed based on the set value of the off temperature.