JPH02192539A - Low temperature cold water making device - Google Patents

Abstract

PURPOSE:To enable a cold water to be cooled down to about 0 deg.C by a method wherein a freezer or a heat pump is controlled to have a brine temperature at an outlet of a cooler of a specified temperature and a cold water supplying pump controls a flow rate of cold water in such a way as a cold water temperature at an outlet port of a heat exchanger keeps about 0 deg.C. CONSTITUTION:A brine temperature at an outlet of a cooler is detected by a tempera ture sensor 12', an instruction is applied from a brine inlet port temperature controller 12 in order to keep this cooler outlet brine temperature constant, a capacity controller 16 is made movable to control a capacity of a compressor 18 for a freezer 1. In turn, a cold water outlet temperature of a heat exchanger is detected by a temperature sensor 13', an instruction is applied from a cold water outlet controller 13 so as to enable a variable speed controller device 6 to be moved and then a flow rate of cold water is increased. Even if a maximum number of revolution is set, in case that a cold water inlet temperature detected by the cold water inlet temperature sensor 14' indicates a tendency to decrease, an instruction is applied from a cold water inlet controller 14, cold water at a high temperature side of a cold water heat accumulator tank 7 is mixed by a motor and then a cold water inlet temperature is kept at a predetermined temperature.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a chilled water production device, and particularly to a cooling device for air conditioning,
This invention relates to an efficient chilled water production device tK used for cooling industrial processes, etc.

[Conventional technology]

When producing chilled water using a refrigerator or a heat pump, the lower limit of the chilled water temperature has conventionally been 5° C. due to concerns about damage to heat transfer tubes due to freezing of the water. In the field of air conditioning, 5 to 7
℃ cold water is sent to the air conditioner and exchanges heat with cold air, approximately 10 to 1
A cycle of rising to 2°C and returning is common. Also, even when using a heat storage device, the effective temperature difference for heat storage is 10℃-5℃
or in the range of 5°C to 7°C of 12°C to 5°C.

On the other hand, in the industrial field, the temperature of the liquid to be cooled varies depending on the process, but the temperature range called mild prine is most commonly used. Mild prine is an ethylene glycol aqueous solution, a propylene glycol aqueous solution, a calcium chloride aqueous solution, or the like. These antifreezes are approximately 5℃
It is used in the range of -50°C.

[Problems that the invention helps solve]

In the field of air conditioning, it is desired to save energy and reduce equipment costs by increasing the temperature difference of circulating water used for air conditioning, reducing the amount of circulating water, and reducing the diameter of transport pipes. Furthermore, there is a limit to the size of heat storage tanks installed in the basements of buildings in cities, so if we could increase the heat storage capacity by keeping the size the same, we would be able to use late-night electricity at cheaper electricity rates. It is desired that such heat storage devices become widespread.

Furthermore, in industrial applications, it has been clear that antifreeze, which has poor heat transfer, high liquid viscosity, and corrosive properties, can be replaced with water as much as possible to save energy and make maintenance management easier.

However, in the prior art, increasing the degree of cooling of the cold water causes the problem of damage to the heat transfer tubes due to freezing, and the temperature of the cold water cannot be lowered sufficiently.

SUMMARY OF THE INVENTION In view of the above-mentioned needs, an object of the present invention is to provide a cold water production device that can cool the cold water to a temperature close to 0° C. without worrying about freezing and damage.

[11! Means for Solving the Problems] The present invention provides equipment for a pline circulation system that includes a refrigerator or a heat pump, a heat exchanger between pline and cold water, pline piping that connects the two, a pline circulation pump, a pline tank, etc. In a cold water production and cold water heat storage device consisting of a cold water circulation system consisting of a cold water pipe connected to a heat exchanger, a cold water supply pump, a cold water heat storage tank, etc., the cold water temperature at the outlet of the heat exchanger is kept close to the freezing point, i.e. In order to maintain the temperature near 0°C, the refrigerator or heat pump is equipped with a means to control the pline temperature at the outlet of the cooler to a constant temperature, and the cold water supply pump is equipped with a means to maintain the chilled water temperature at the outlet of the heat exchanger near 0°C. This is a chilled water production device comprising means for controlling the flow rate of chilled water.

Next, the present invention will be explained in detail.

In the present invention, in an apparatus for producing chilled water by producing a pline at a temperature of 0° C. or lower using a refrigerator or a heat pump, passing this pline into a tube of a heat exchanger, and passing cold water through the outside of the tube, , to control the cold water outlet temperature to maintain it at a temperature close to 0°C without freezing.

Therefore, the chiller or heat pump sets the prine temperature based on a predetermined heat exchange amount, a predetermined cold water inlet temperature, and a cold water flow rate so that the cold water outlet temperature is close to 0°C without freezing. Control is performed to maintain the temperature. - At the same time as the above control, the cold water side is also controlled so that the cold water outlet temperature approaches Oc.

The above-mentioned control on the chilled water side means that a chilled water pump with a variable speed control device is installed on the chilled water inlet side, detects the chilled water outlet temperature, and adjusts the output of the temperature controller so that the chilled water outlet temperature is close to 0°C. This is applied to a variable speed control device to change the chilled water flow rate of the chilled water pump.

Here, the fact that the cold water temperature at the heat exchanger outlet is close to 0°C means that a part of the heat exchanger is in a so-called supercooled state below 0°C, so the amount of heat exchanged due to the decrease in the cold water inlet temperature is Decrease is the condition most likely to cause freezing.

Therefore, in the present invention, when the cold water inlet temperature decreases, first, the cold water pump variable speed device is activated to increase the cold water flow rate, thereby controlling the heat exchanger to be kept constant.

Then, this variable speed device reaches the maximum rotation speed, and
If the cold water inlet temperature shows a tendency to decrease, the cold water inlet temperature is controlled to be maintained at a predetermined temperature by mixing the supplied cold water with cold water of a higher temperature from the cold water heat storage tank.

Another control method is to constantly detect the chilled water inlet temperature, and when the chilled water inlet temperature drops below a predetermined value, the cooling heat amount of the brine cooled by the refrigerator or heat pump is reduced, reducing the load on the chilled water side. This is a method of matching and controlling.

Specifically, the capacity control mechanism of a refrigerator or heat pump is usually controlled by the brine temperature (heat exchanger population), and when the cold water inlet temperature decreases, the deviation between the predetermined cold water inlet temperature and the actual inlet temperature is minutes to the brine temperature controller;
Control is performed to increase the brine temperature, that is, to reduce the amount of heat for cooling the brine by the refrigerator or heat pump, thereby reducing the amount of heat exchanged with cold water.

〔Example〕

The present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

Embodiment 1 FIG. 1 shows 70 of a cold water production apparatus showing an embodiment of the present invention.
- Schematic diagram.

In the Mi diagram, 1 is a cold SI machine or a heat pump, 2 is a heat exchanger between brine and cold water, and 7 is a cold water heat storage tank.

In the refrigerator or heat pump, 17 is a cooler,
1B represents a compressor, brine is cooled in a cooler 17, heat exchanged with cold water in a heat exchanger 2, stored in a brine tank 4, and pumped into a prine pump 3.
Otherwise, a cycle is taken to circulate to the cooler 17. On the other hand, cold water is sent from the high temperature side a of the cold water heat storage tank 7 to the heat exchanger 2 by the cold water primary bong 5, where it is cooled by brine and returned to the low temperature side of the cold water heat storage tank 7. The cold water in the low temperature side of the cold water heat storage tank 7 is transferred to the cold water secondary bong 8.
．． 10: The cold water, which is sent to the air conditioning load 9.11 and whose temperature has increased, is circulated to the high temperature side a of the cold water heat storage tank 7.

By the way, in such a circulation system, in normal operation, the temperature detector 12' detects the brine temperature at the outlet of the cooler, and the brine inlet temperature controller 12 instructs the brine inlet temperature controller 12 to maintain this temperature constant. 16 is moved to control the capacity of the compressor 18 of the refrigerator 1. on the other hand,
Detecting the cold water outlet temperature of the heat exchanger with a temperature detector 13',
In order to maintain this temperature near 0° C., the cold water outlet controller 13 commands the variable speed control device f16 to adjust the flow rate of the cold water of the primary cold water pump 5.

Then, even if the chilled water pump variable speed device 6 is operated to increase the chilled water flow rate and the rotation speed is set to the maximum, if the chilled water inlet temperature detected by the chilled water inlet temperature detector 14' shows a tendency to decrease, the chilled water In response to a command from the inlet controller 14, the cold water on the high temperature side a of the cold water heat storage tank 7 is mixed by the motor to maintain the cold water inlet temperature at a predetermined temperature.

Another control method is to constantly detect the chilled water inlet temperature with a temperature detector 15', and when the chilled water inlet temperature falls below a predetermined value, the deviation between the predetermined chilled water inlet temperature and the actual inlet temperature is detected. The cold water inlet temperature is read by the cascade stacker 15, and the capacity control device 16 is movably controlled to increase the pline temperature (heat exchanger inlet) by that amount, thereby reducing the heat exchange capacity with the cold water.

〔Effect of the invention〕

In the present invention, cold water close to 0° C. can be produced without freezing. Conventionally, in the air conditioning field, a chilled water circulation system sends cold water at 5°C, returns it at 10°C from an air conditioner, and cools it down to 5°C again in a refrigerator, but in this case, a temperature difference of 10-5°C and 5°C is used. Therefore, if water at 0°C can be obtained as in the present invention, a temperature difference of 10-0 = 10°C can be utilized.

As mentioned above, in the present invention, twice the temperature difference can be used compared to the conventional one, so from the following equation, the amount of circulating water can be halved, and the pump power (conveying power) and pipe diameter can be reduced. There is a certain effect.

Q = G x ΔTxrxh = (
1) On the other hand, the heat storage capacity can also be changed by replacing the equation 11 with Gt - the amount of water held in the heat storage tank, so that the temperature difference Δ that can be effectively used is
By doubling T, the heat storage capacity can also be doubled.

[Brief explanation of the drawing]

FIG. 1 is a schematic flow diagram of a cold water production apparatus showing an embodiment of the present invention. 1... Refrigerator or heat pump, 2... Heat exchanger,
3... Brine pump, 4... Brine tank, 5
...Cold water primary pump, 6.Variable speed control device, 7.
...Cold water heat storage tank, 8.10...Cold water secondary pump, 9.
11... Air conditioning load, 12', 13', 14', 15'
...Temperature detector, 12-...Brine inlet temperature controller, j5-...Cold water outlet controller, 14...
Chilled water inlet controller, 15--Cold water inlet temperature cascade integrator, 16--Capacity control device, 17--Cooler, 18--Compressor, a--High temperature side, b--Low temperature side

Claims (1)

[Scope of Claims] 1. Equipment of a pline circulation system consisting of a refrigerator or heat pump, a heat exchanger between pline and cold water, pline piping connecting the two, a pline circulation pump, a pline tank, etc., and a heat exchanger. In a cold water production and cold water heat storage system consisting of cold water piping connected to a heat exchanger, a cold water circulation system consisting of a cold water supply pump, a cold water heat storage tank, etc., the temperature of the cold water at the outlet of the heat exchanger is kept close to the freezing point, that is, close to 0°C. In order to maintain this temperature, the refrigerator or human pump is equipped with a means to control the pline temperature at the outlet of the cooler to a constant temperature, and the cold water supply pump is equipped with a means to control the flow rate of cold water so that the temperature of the cold water at the heat exchanger outlet is maintained near 0°C. A chilled water production device comprising means for controlling. 2. The chilled water production apparatus according to claim 1, further comprising means for mixing cold water of different temperatures in the cold water heat storage tank so that the temperature of the cold water inlet of the heat exchanger can be controlled to a constant temperature. 3. In the chilled water production apparatus according to claim 1, when the chilled water inlet temperature decreases, capacity control of the refrigerator or heat pump is switched from Pline's cooler outlet temperature control to chilled water inlet temperature control, so that the chilled water inlet temperature decreases. A chilled water production device comprising a control means for increasing the prine temperature by the same amount.