JPH0875220A - Inlet temperature control method of cold water for refrigerator in water heat accumulating system - Google Patents

Abstract

PURPOSE: To contrive the energy saving of a system by a method wherein the performance coefficient of a refrigerating machine is improved and the cooling capacity of the same is increased utilizing the cooling capacity of cooling water, which is increased by the reduction of an outside air wet-bulb temperature, while the operation times of related auxiliary machines are shortened in accordance with the operation time of the refrigerating machine, shortened by the increase of the cooling capacity of the same. CONSTITUTION: In a water heat accumulating system, in which the sending pipe 9 of cold water system 5 for a refrigerating machine is connected to the low temperature side 1a of a heat accumulating tank 1 while returning pipes 13, connected to the low temperature side 1a and the high temperature side 1b of the heat accumulating tank 1, are joined in a mixing three-way valve 11 and, thereafter, the joined returning pipe is connected to the cold water inlet port 7b of the cold water system 5 for the refrigerating machine, the set temperature of the mixing three-way valve 11, detecting and controlling the cooling water inlet temperature of a cooling water system 23, is changed automatically to a set value of temperature higher than said set temperature when the detecting value has become lower than the set temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an efficient operation technique of heat source equipment in a water heat storage system which is one of the heat source systems for buildings and district heating and cooling.

[0002]

2. Description of the Related Art A water heat storage system is provided with a refrigerator for circulating cold water to a heat storage tank. When the refrigerator is a water-cooled type, a cooling tower is connected to the condenser by a cooling water pipe. That is, the heat absorbed from the heat storage tank is exhausted to the outside air from the cooling tower via the condenser of the refrigerator (hereinafter, the water pipe on the heat absorption side passing through the heat storage tank is referred to as “heat storage system”). "The water pipe on the exhaust heat side that passes through the cooling tower is called the" cooling water system. "

Further, in the water heat storage system, the cold water inlet of the heat storage system is connected to the low temperature water side and the high temperature water side of the heat storage tank via the mixing three-way valve, and the mixing three-way valve allows the low temperature side,
By appropriately controlling the mixed water amount ratio on the high temperature side, the cold water inlet temperature is controlled to be constant, and stable and highly efficient operation of the refrigerator is realized.

On the other hand, also in the cooling water system of the refrigerator, the cooling water inlet is connected to the piping from the cooling tower through the mixing three-way valve and the direct piping from the cooling water outlet not passing through the cooling tower, and this mixing three-way system. The valve appropriately controls the mixed water amount ratio from the cooling water outlet side and the cooling tower passing side so that the cooling water inlet temperature does not fall below the limit temperature of the refrigerator (for example, below 25 ° C).

[0005]

Conventionally, each device of the heat storage system and the cooling water system related to the refrigerator of the water heat storage system is
The rated capacity is set up to the upper limit of summer conditions when the load increases. The temperature condition value in summer, which is a standard for calculating the rated capacity, is, for example, cooling water inlet temperature; 32 ° c, cold water inlet temperature; 10 ° c, cold water outlet temperature; 5 ° c. However, the cooling water circulating in the condenser of the refrigerator is cooled by the cooling tower installed outside after exiting the cooling water outlet and returned to the cooling water inlet again, so that the season and humidity (that is, outside air humidity) The cooling capacity of the cooling tower increases or decreases depending on the sphere temperature, and the cooling water inlet temperature fluctuates greatly. Therefore, in the intermediate period, particularly in winter, the cooling water inlet temperature is significantly lower than the rated condition value (32 ° c in the above example). On the other hand, however, the cold water inlet temperature is generally kept constant throughout the year. Therefore, the cooling capacity of the cooling water system, which increases due to the decrease in the outside air wet-bulb temperature in the middle and winter seasons, has not been fully utilized at present.
The present invention has been made in view of the above situation, and by utilizing the cooling capacity of a cooling water system that increases due to a decrease in outside air wet bulb temperature, the refrigerating function is increased, and as a result, the coefficient of performance of the refrigerator is improved. At the same time, by providing a method for controlling the cold water inlet temperature of a refrigerator in a water heat storage system that can reduce the operating time of the refrigerator and related accessories (for example, a cooling water pump, a cold water pump, etc.), it is possible to save energy in the system. To aim.

[0006]

According to the method for controlling the cold water inlet temperature of a refrigerator in a water heat storage system according to the present invention for achieving the above object, a forward pipe of a refrigerator cold water system is connected to a low temperature side of a heat storage tank. After the return pipes connected to the low temperature side and high temperature side of the heat storage tank are integrated by the mixing three-way valve, they are connected to the cold water inlet of the refrigerator cold water system, while the forward pipe of the refrigerator cooling water system is the cooling tower. In the cooling water inlet temperature control method of the refrigerator in the water heat storage system in which this cooling tower is connected to the cooling water inlet of the refrigerator cooling water system by the return pipe, the cooling water inlet temperature of the cooling water system is detected, The set temperature of the mixing three-way valve for controlling the cold water inlet temperature is automatically changed according to the change of the detected value.

[0007]

With the decrease in the outside air wet bulb temperature, the inlet temperature of the cooling water cooled by the cooling tower becomes low, and the decrease in the condensation temperature increases the cooling capacity of the refrigerator.
The set temperature of the mixing three-way valve for controlling the cold water inlet temperature is automatically changed according to the change of the cooling water inlet temperature. At this time, the refrigerator cools the chilled water to a constant outlet temperature by the cooling capacity increased due to the decrease of the cooling water inlet temperature, so that the coefficient of performance is improved and the capacity per unit time is increased, and the operating time is shortened. At the same time, the operating time of auxiliary equipment, such as a chilled water primary pump and a chilled water pump, is shortened at the same time, and the electric power is saved accordingly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a cold water inlet temperature control method for a refrigerator in a water heat storage system according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a water heat storage system for carrying out the cold water inlet temperature control method according to the present invention. A low temperature side 1a and a high temperature side 1b are formed in the heat storage tank 1, and a temperature distribution is formed in the heat storage tank to store water.
A secondary cooling water pipe (not shown) is connected to the heat storage tank 1, for example, and cold water is taken out by supplying cold water to an air conditioner or the like.

A cold water system 5 of a refrigerator 3 is connected to the heat storage tank 1. The cold water system 5 includes a cold water outflow pipe 9 that connects a cold water outlet 7a provided in the cooler 7 of the refrigerator 3 and the low temperature side 1a of the heat storage tank 1, and pipes from the low temperature side 1a and the high temperature side 1b to the cold water system side. The cold water return pipe 13 which is once connected to the mixing three-way valve 11 and is connected to the cold water inlet 7b of the cooler 7. The cold water return pipe 13 is provided with a cold water primary pump 15, and the cold water primary pump 15 circulates the water from the heat storage tank 1 to the cooler 7 of the refrigerator 3.

A controller 17 is connected to the mixing three-way valve 11 on the cold water system side, and the controller 17 is the cold water inlet 7b.
Based on the temperature detected by the temperature detector 19 provided in the vicinity, the mixing three-way valve 11 is controlled so that the cold water inlet temperature matches the set temperature. That is, when the cold water inlet temperature is lower than the set value, the water amount from the high temperature side 1b is increased to raise the cold water inlet temperature, and when the cold water inlet temperature is higher than the set value, the water amount from the low temperature side 1a is increased. Control is performed to increase the cold water inlet temperature to lower it.

On the other hand, a cooling water system 23 is connected to the condenser 21 of the refrigerator 3. The cooling water system 23 includes a cooling water outflow pipe 27 that connects the cooling water outlet 21 a of the condenser 21 and the cooling tower 25, and a pipe from the cooling water outlet 21 a and the cooling tower 25 to the mixing three-way valve 29 on the cooling water system side. Once connected to condenser 21
And a cooling water return pipe 31 connected to the cooling water inlet 21b. A cooling water pump 33 is provided in the cooling water outflow pipe 27, and the cooling water pump 33 transfers the cooling water to the condenser 21 and the cooling tower 2.
Circulate between 5 and 5.

A controller 35 is connected to the mixing three-way valve 29 on the cooling water system side, and the controller 35 sets the cooling water inlet temperature based on the temperature detected by a temperature detector 37 provided near the cooling water inlet 21b. The mixing three-way valve 29 is controlled to match the temperature. That is, when the cooling water inlet temperature is low, the amount of water from the cooling water outlet 21a is increased to raise the cooling water inlet temperature, while when the cooling water inlet temperature is high, the amount of water from the cooling tower 25 is increased. Then, control is performed to lower the cooling water temperature.

In this embodiment, the controller 35 for controlling the mixing three-way valve 29 on the cooling water system side and the controller 17 for controlling the mixing three-way valve 11 on the cooling water system side are electrically connected by the signal wiring 39. The cooling water inlet temperature detected value is sent from the controller 35 for controlling the cooling water inlet temperature to the controller 17 for controlling the cooling water inlet temperature. The controller 17 can perform setting change control of the cold water inlet temperature (for example, changing the cold water inlet temperature 10 ° c to 10.5 ° c) based on the detected cooling water inlet temperature. As a method of transmitting the detected value of the cooling water inlet temperature, in addition to the present embodiment, the controller 35 for controlling the cooling water inlet temperature transmits it to the controller 17 for controlling the cooling water inlet temperature via a central monitoring device or the like. , Transmission from the cooling water inlet temperature detector 37 to the controller 17 for controlling the cooling water inlet temperature, transmission from the controller 35 for controlling the cooling water inlet temperature to the controller 17 for controlling the cooling water inlet temperature via a central monitoring device or the like. Etc. are possible.

At this time, the chilled water inlet temperature is controlled so that the chilled water outlet temperature (5 ° c in the above example) is constant.
It works. By the PI operation, unlike the case of only the proportional operation, the feedback control for simultaneously performing the P operation (the proportional operation that outputs a signal proportional to the deviation) and the I operation (the integral operation that outputs the signal for removing the residual deviation) is performed. This makes it possible to keep the cold water outlet temperature constant.

The operation of controlling the cold water inlet temperature in the water heat storage system thus configured will be described. When the outside-air wet-bulb temperature is high, such as in the summer, the inlet temperature of the cooling water cooled by the cooling tower 25 is 32 ° c at the rated capacity condition value (outside-air wet-bulb temperature 27 ° c). Therefore, in this state, the cooling capacity of the refrigerator 3 becomes the rated value.

On the other hand, the inlet temperature of the cooling water cooled by the cooling tower 25 decreases as the outside-air wet-bulb temperature decreases in the middle period, especially in winter. In this state, the cooling capacity of the refrigerator 3 increases due to the decrease in the condensation temperature.
Therefore, the cooling water inlet temperature detected value is sent from the controller 35 for controlling the cooling water inlet temperature to the controller 17 for controlling the cold water inlet temperature, and the controller 17 automatically changes the setting value of the cold water inlet temperature. Depending on the characteristics of the refrigerator 3, the set temperature of the cold water inlet is increased as the detected value of the cooling water inlet is decreased, and the set temperature of the cold water inlet is decreased as the detected value of the cooling water inlet is increased.

At this time, the refrigerator 3 cools the chilled water to a constant outlet temperature (5 ° C. in the above example) by the cooling capacity increased by the decrease of the cooling water inlet temperature, so that the capacity per unit time is reduced. Will increase and the operating time will be shortened. In addition, the coefficient of performance of the refrigerator at this time is higher than that under the rated conditions. Further, since the operating time of the refrigerator 3 is shortened, the operating time of the auxiliary equipment, for example, the cold water primary pump 15, the cooling water pump 33, etc. is also shortened, and the electric power is saved accordingly.

As described above, according to the cooling water inlet temperature control method for the refrigerator in the water heat storage system described above, by detecting the cooling water temperature, the cold water inlet temperature is automatically changed and set by the signal, Since the surplus capacity of the refrigerator can be sufficiently drawn out, the coefficient of performance of the refrigerator can be improved and the operating time of the refrigerator and auxiliary equipment can be shortened, and power consumption can be reduced accordingly. It will be possible.

In the above embodiment, the case where the chilled water outlet temperature is kept constant at 5 ° C. has been described as an example. However, the control for raising the chilled water outlet temperature when the cooling load is small, such as in the intermediate period and the winter season, is used. It can also be performed in combination. By thus increasing the chilled water temperature level, the coefficient of performance of the refrigerator 3 is further improved, and as a result, the operating time of the refrigerator 3 can be further shortened and the power consumption can be reduced accordingly. Becomes

[0020]

As described in detail above, according to the method for controlling the cold water inlet temperature of the refrigerator in the water heat storage system according to the present invention, the cold water inlet temperature can be controlled especially in the middle period and winter when the cooling water capacity increases. Since the setting is changed to a high temperature so that the surplus capacity of the refrigerator can be sufficiently drawn out, the coefficient of performance of the refrigerator can be improved and the operating time of the refrigerator and auxiliary equipment can be shortened. As a result, it is possible to reduce the amount of electric power by that amount and achieve energy saving of the system.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a water heat storage system for implementing a cold water inlet temperature control method according to the present invention.

[Explanation of symbols]

 1 Heat Storage Tank 1a Low Temperature Side 1b High Temperature Side 3 Refrigerator 5 Cold Water System 7a Cold Water Outlet 7b Cold Water Inlet 9 Outgoing Pipe 11 Mixing Three-way Valve 13 Return Pipe 21b Cooling Water Inlet 23 Cooling Water System 25 Cooling Tower 27 Forwarding Pipe 31 Return Pipe

Claims (2)

[Claims] 1. The refrigerator after the forward pipe of the refrigerator cold water system is connected to the low temperature side of the heat storage tank, and the return pipes connected to the low temperature side and the high temperature side of the heat storage tank are integrated by a mixing three-way valve. In a water heat storage system in which the forward pipe of the refrigerator cooling water system is connected to the cooling tower while being connected to the cold water inlet of the cold water system, and the cooling tower is connected to the cooling water inlet of the refrigerator cooling water system by the return pipe In the cold water inlet temperature control method for a refrigerator, the cooling water inlet temperature of the cooling water system is detected, and the set temperature of the mixing three-way valve that controls the cold water inlet temperature is automatically changed according to the change in the detected value. A cold water inlet temperature control method for a refrigerator in a water heat storage system, comprising: 2. The cooling water outlet temperature is automatically changed to a set value higher than the set value at the time of cooling load reduction in the middle season, winter season, etc., and at the same time, the cooling water inlet temperature of the cooling water system is detected, A method for controlling a cold water inlet temperature of a refrigerator in a water heat storage system, wherein a preset temperature of the mixing three-way valve for controlling a cold water inlet temperature is automatically changed according to a change in the detected value.