JPH0827039B2 - Ice heat storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an ice heat storage device used for air conditioning and the like.

(Prior Art) Since an air conditioning system having ice heat storage can use inexpensive late-night power in order to reduce power demand for cooling concentrated in the daytime, and contract power can be reduced by halving the heat source equipment capacity. It is expected to be applied to building air conditioning systems and relatively large capacity air conditioning systems such as district heating and cooling systems.

This ice heat storage device is roughly classified into an indirect heat exchange system and a direct heat exchange system in the ice production method.

The indirect heat exchange method is a method that uses a heat transfer tube for ice making (copper tube, polyethylene tube, etc.), and a low-temperature refrigerant (CFC, etc.) or antifreeze liquid (commonly known as brine) is flown inside or outside the heat transfer tube. Ice on the opposite wall of
This is a method of landing on ice.

This method of forming ice on the outer and inner wall surfaces of the heat transfer tube causes ice to accumulate as the thickness of the ice generated on the wall gradually increases.
Since the thermal conductivity of ice itself is very small, the amount of heat transferred from the water to be cooled to the cooling medium (CFC, brine) becomes smaller according to the thickness of the ice, and the growth rate of ice becomes slower.
In order to increase the growth rate of this ice, it is necessary to lower the temperature of the cooling medium, but if the temperature of the cooling medium is lowered, there is a drawback that the coefficient of performance of the refrigerator decreases.

In addition, in the method of arranging the heat transfer tube in the water tank and immersing it in water, the ice filling rate (commonly called IPF: ICE Packing Factor) is
It is better that the pitch of the heat transfer tubes is smaller, but in this case, a large number of heat transfer tubes are arranged in the water tank, and the volume occupied by ice is reduced. On the contrary, if the pitch of the heat transfer tube is increased and the thickness of the ice accreting on the surface of the heat transfer tube is increased, as described above,
Not only does the coefficient of performance of the refrigerator decrease, but when the ice water is thawed and cold water is taken out, the degree of decrease in the thickness of ice in the heat transfer tube group and in the circumferential direction of one heat transfer tube becomes uneven, and cold water The take-out temperature may cause hatching. In the worst case, the ice that has adhered to adjacent heat transfer tubes during ice making / thawing may come into contact with each other (commonly known as bridging), giving extra force to the heat transfer tubes and damaging the heat transfer tubes. is there.
Therefore, it is difficult to raise the ice filling rate (IPF) as a whole, and the heat storage efficiency is not necessarily much better than that of the heat storage water tank (cold water heat storage).

In addition, in this indirect heat exchange system, the ice making section and the ice are stored instead of immersing the heat transfer pipe for ice making in consideration of the decrease in the filling rate of ice and the decrease in the coefficient of performance of the refrigerator. An ice heat storage system, which is commonly called a harvest type with a separate tank, has been devised. This type of ice heat storage system has an ice making part installed on the top, and ice of a constant thickness (thickness that does not decrease the coefficient of performance of the refrigerator) is deposited on the surface of the heat transfer tube for ice making. After that, the surface of the heat transfer tube is warmed with a high-temperature refrigerant gas (compressor discharge gas) and the ice made is stored in the lower storage tank.

However, in this method, there is a two-step process of cooling (ice making) -heating (ice falling) of the heat transfer tube in the upper ice making part, and the control becomes complicated, and in addition, the thaw of the lower ice storage tank It is difficult to do it uniformly. Moreover, the size of the ice making unit is not so different from that of the conventional ice heat storage tank, resulting in a large system as a whole.

In addition, as a kind of indirect heat exchange method, heat is exchanged (cooled) through a heat transfer tube for ice making, but in this case, a liquid in which an antifreeze liquid such as ethylene glycol is mixed with water is used as a liquid to be cooled, There is one that uses a continuous flow of supercooled water that utilizes the phenomenon that if water is flowed at a certain flow velocity, it does not freeze even at 0 ° C or lower.

The method using a mixture of water and an antifreeze liquid in the liquid to be cooled is such that the liquid to be cooled is cooled through a heat transfer tube for ice making, and the freezing temperature (lower than 0 ° C.) or lower is applied to the liquid to be cooled. Freeze the water inside to form a shear bed (solid-liquid two-phase flow),
It is a system that can be transported as it is. Since this system mixes antifreeze and water, the viscosity and thermal conductivity are poor, and not only the heat exchange performance is low, but when the water in the liquid to be cooled is frozen, the antifreeze liquid in the liquid to be cooled will The higher the concentration, the lower the freezing temperature of water. Therefore, in order to freeze this water, the temperature of the cooling liquid to be cooled must be lowered more and more, and there is a problem that the coefficient of performance of the refrigerator further decreases. Further, to directly convey this sheared liquid to be cooled to the air conditioner, not only the pump power becomes very large, but also because the temperature of this liquid to be cooled is low, condensation occurs on the air side of the air conditioner, It shortens the life of the air conditioner.

The method of exchanging heat of the supercooled water (about -4 ° C) is a method of supercooling the water temperature to 0 ° C or less in the process of continuous flow of water, and when returning the continuous flow of the supercooled water to the heat storage water tank. This is a system in which a collision plate is installed to eliminate kinetic energy, part of the supercooled water is deposited as ice particles, and stored in a heat storage water tank. With this method, it can be stored in a sheared ice water storage tank, and the coefficient of performance of the refrigerator is high because it does not make ice on the surface of the heat transfer tubes. The ice filling rate is also high because the water tank contains only ice particles and water. However, since it is necessary to flow water without stagnation in the process of creating a continuous flow of this supercooled water, only a straight pipe can be used. Among these straight pipes, the part that makes the water flow uniform from the inlet, cooling by the cooling liquid It is necessary to increase the length of the straight pipe, and this supercooler itself becomes large in size, and the installation space becomes a problem. In addition, it is difficult to control the temperature of the supercooled water itself as the flow rate of the supercooled water increases, and in reality, it is difficult to use a refrigerant as the cooling liquid.
The coefficient of performance of the refrigerator is not so good because supercooled water is produced through the brine because a frozen layer may be generated in the pipe due to the non-uniformity of evaporation heat transfer.

On the other hand, the direct heat exchange method is a method in which a refrigerant gas is directly blown into water. This direct heat exchange method blows the low-temperature refrigerant after it leaves the expansion valve in the refrigerator into the water from the bottom and sides of the water tank, so the temperature of the cooling liquid (refrigerant) is higher than that of the indirect heat exchange method. Therefore, the coefficient of performance of the refrigerator is good. In addition, since the heat exchange is performed by direct contact between the refrigerant and water in the water tank, the heat exchange performance is good, and there is nothing that occupies the volume of the heat transfer tubes etc. in the water tank.
F) is also good. Since the portion of the refrigerator corresponding to the evaporator directly serves as the ice heat storage tank, the system can be simplified.

However, if water enters the refrigerant gas (usually CFC),
Refrigerant and water react to generate corrosive chlorine gas,
Since it is not possible to mix the lubricating oil for the compressor contained in the refrigerant into the water tank, it is necessary to separate the refrigerant and the lubricating oil. Conversely, the water contained in the refrigerant gas that evaporates in the water tank cannot be mixed in the compressor. It is also necessary to remove the water content in the refrigerant gas, since this will cause adverse effects. Moreover, since the ice heat storage tank which is also this evaporator becomes a high-pressure container, it is not suitable for upsizing.

(Problems to be Solved by the Invention) Although methods for manufacturing ice heat storage are roughly classified into a direct heat exchange system and an indirect heat exchange system, they have individual drawbacks as described below. In other words, the method of making and icing ice on the surface of the heat transfer tube has drawbacks such as a low coefficient of performance of the refrigerator, a low ice filling rate, poor deicing performance, and damage to the heat transfer tube.

The system that combines the ice making unit and the ice storage tank has a complicated structure, and has the drawback of increasing the overall size.

The method of mixing water and antifreeze with the liquid to be cooled has drawbacks such as a low coefficient of performance of the refrigerator, an increase in transport power, and an adverse effect on the air conditioner.

The method that uses a continuous flow of supercooled water has drawbacks such as lengthening of the supercooler and difficulty in controlling the temperature of the supercooled water.

The method in which the refrigerant liquid (gas) is directly blown into water has the drawbacks of generation of corrosive gas, necessity of separation of oil and water, and high pressure vessel.

However, as a whole, deicing is not practically performed well.

The present invention provides the above-mentioned drawbacks of the ice heat storage device, that is, a reduction in the coefficient of performance of the refrigerator, a low ice filling rate, a deicing performance, and an ice heat storage device that avoids the complexity and size of the system. The purpose is to provide.

[Structure of Invention]

(Means for Solving the Problems) The ice heat storage device of the present invention is provided with a reservoir at the bottom of the ice heat storage tank, and water having a specific weight of 1.5 times or more and a freezing point of minus 50 ° C. or less is provided in the reservoir. The insoluble Fluorinert solution is stored in the tank, and the Fluorinert solution is kept at a temperature of 0 ° C or lower by a refrigeration cycle. The ice heat storage tank and the storage section are connected by piping, and the water in the ice storage tank is stored in the Fluorinert solution. It is configured to spray ice to deposit ice.

(Operation) In the ice heat storage device of the present invention, the water in the ice heat storage tank is sprayed on the Fluorinert liquid in the storage portion through the pipe, and the water in the spray state is kept at a temperature of 0 ° C. or lower by the refrigeration cycle. By directly exchanging heat with the Fluorinert liquid and cooling it directly, the water becomes ice when the temperature becomes 0 ° C or less, rises to the upper part due to the influence of buoyancy due to the difference in specific gravity, and enters the water located above. When the water and the Fluorinert enter together, the water and the Fluorinert are completely separated, and the ice is collected on the upper surface of the water,
Fluorinert settles to the bottom, forming ice blocks in the ice storage tank.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of the ice heat storage device according to the present invention.
The bottom portion 2 of the ice heat storage tank 1 of this ice heat storage device is an inclined surface inclined downward from the lower end of the side wall portion 3 toward the center,
A storage tank 4 is provided integrally with the ice heat storage tank 1 at the center of the bottom portion 2. A straightening plate 5 is arranged in the storage tank 4 so as to extend in the vertical direction, and the interior of the storage tank 4 is divided into two chambers.
It is divided into a and 4b. The length of the straightening vane 5 is shorter than the height of the storage tank 4, and the communication portion 7 is formed between the lower end of the straightening vane 5 and the bottom portion 6 of the storage tank 4, and the communication portion 8 is formed above the straightening vane 5. The plate 5 forms a circulating flow through the chamber 4a and the chamber 4b of the storage tank 4.

A heat exchanger 9 is arranged in one chamber 4b of the storage tank 4, and the heat exchanger 9 is connected via a pipe 10 to a refrigerator 11 provided outside, and a Fluorinert housed in the storage tank 4 is provided. liquid
I'm trying to cool 12.

The Fluorinert liquid 12 is a colorless, transparent, odorless, and inert liquid, has a completely fluorinated structure, and is a bond of only carbon atoms C and fluorine atoms F. This Fluorinert liquid 12 has a boiling point and a freezing point (same as the pour point) depending on the number of bonds of carbon atoms C and fluorine atoms F, but the freezing point is -20.
Most are below ℃. And the specific weight is 0 ℃
In the vicinity, it is 1.7 to 1.8 kg / l, which is about twice that of ice. Further, the solubility of water in Fluorinert is as low as 7.2 ppm at a temperature of 10 ° C, and it can be considered that it is insoluble. Therefore, when water and Fluorinert are put together in the water tank, they are completely separated, and the Fluorinert settles on the bottom, and the water floats on it.

In the present invention, the Fluorinert liquid 12 having a specific weight of 1.7 to 1.8 times that of water and a freezing point of about −50 ° C. is selected.

On the other hand, a water intake 13 is provided above the side wall 3 of the ice heat storage tank 1, and a partition plate 14 is arranged inside the ice heat storage tank 1 so as to surround the water intake 13. Also, storage tank 4
A nozzle 15 is arranged at a portion of the bottom portion 6 corresponding to the chamber 4a. The water intake 13 provided on the side wall portion 3 and the nozzle 15 provided on the bottom portion 6 are connected by a pipe 16. A filter 17, a water blowing pump 18, and a check valve 19 are arranged in this pipe 16 in this order from the water intake 13.

 It should be noted that reference numeral 20 in FIG. 1 is a generated ice block.

 Next, the operation will be described.

First, the Fluorinert liquid 12 is stored in the storage tank 4, and the ice heat storage tank 1 is filled with water 21 up to a predetermined liquid level. Since the Fluorinert liquid 12 in the storage tank 4 and the water 21 in the ice heat storage tank 1 are insoluble, both liquids are completely separated, and the interface 22 between the water 21 and the Fluorinert liquid 12 is always present.

Then, the refrigerator 11 is operated to keep the Fluorinert solution 5 stored in the storage tank 4 at 0 ° C. or lower by the heat exchanger 9.

Next, the water blowing pump 18 provided in the pipe 16 is operated to remove the water in the ice heat storage tank 1 from the water intake 13 provided in the side wall 3.
Water is taken from the filter, foreign matter contained in the water is collected by the filter 17, and then blown into the Fluorinert liquid 12 from the water blowing nozzle 15 through the check valve 10. The water 4 blown into the Fluorinert liquid 12 becomes sprayed water lumps (grains) 23 of water in the Fluorinert liquid 5, and is exchanged with the Fluorinert liquid 12 by the injection pressure and buoyancy, and while being cooled, the arrow A Ascend to the top as shown by, and water 21 and Fluorinert liquid
It goes up through the interface 22 with 12 and rises in the upper water. At this time, what becomes ice by cooling with the Fluorinert liquid 12 further rises in the water, rises to near the liquid surface (bottom surface of ice when ice already exists), and ice blocks (grains) are accumulated.

On the other hand, in the Fluorinert storage tank 4, the Fluorinert solution is
As the sprayed water mass or ice mass (grain) rises in 12
As shown in FIG. 2, the Fluorinert liquid 12 produces an ascending flow while being heated. However, the Fluorinert liquid 12 is provided with the Fluorinert liquid rectifying plate 13, so Fluorinate liquid 12
Rises, and a descending flow occurs in the portion of the refrigerator 11 where the heat exchanger 9 is arranged, and a circulating flow of the Fluorinert liquid 12 occurs. Due to the generation of this circulating flow, good heat exchange between the Fluorinert liquid 12 and the refrigerant flowing in the heat exchanger 9 is maintained, and the Fluorinert liquid 12 at 0 ° C. or less can be always obtained.

In addition, when the Fluorinert liquid 12 rises together with the upward flow of the spray water mass or the ice lump and jumps out from the Fluorinert storage tank 4, there is almost no convection of water in the upper ice heat storage tank 1, The associated Fluorinert liquid 12 descends and flows back along the bottom inclined plate 2 to be returned to the Fluorinert storage tank 4 again.

Then, in the Fluorinert solution 12 of the cooling medium, water is continuously precipitated as ice and stored as ice in the upper part of the water, so the filling rate of ice is high, the viscosity is low, and the Fluorinert solution with a small surface tension is used. Since 12 and the water mass exchange heat directly, the heat exchange rate between the Fluorinert liquid 12 and water is very good. Further, the heat exchange between the heat exchanger 9 of the refrigerator 11 and the Fluorinert liquid 12 has a good heat exchange rate because the Fluorinert liquid 12 has a circulating flow by blowing water from the bottom. Therefore, the coefficient of performance of the refrigerator 11 is also relatively high. Then, since water is blown into the Fluorinert liquid 12 to be cooled in the state of a water mass, the size of the generated ice is small, and the ice particles are stored as ice particles, so that the deicing performance is good.

Moreover, since the Fluorinert storage tank 4 which is a cooling / ice precipitation portion is provided below the ice heat storage tank 1, and only the pump 18 for blowing in water, the check valve 19 and the pipe 16 for connecting them are installed. The system is simple and can be easily enlarged. In addition, since the Fluorinert liquid 12 has a high boiling point of 50 ° C. or higher and does not float on the water surface, the Fluorinert liquid 12 rarely decreases with use, and moreover, it does not remain on the bottom of the ice heat storage tank 1. Since there is the bottom inclined plate 2, the Fluorinert liquid returns to the storage tank 4, and since the Fluorinert liquid 12 does not contain Cl atoms, it does not destroy the ozone layer and has a high boiling point (50 ° C or higher).
The amount that diffuses into the atmosphere is small, and since it is inert, there is no adverse effect on the environment. The water tank is open to the atmosphere and a simple container is sufficient.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the refrigerator 11 is provided near the inside of the side wall of the Fluorinert storage tank 4.
Of the heat exchanger 9a, and a water injection nozzle 15 is installed at the center of the bottom of the Fluorinert storage tank 4. Even with this configuration, in the center, the sprayed water mass or ice mass (grains) that rises due to the blowing pressure and buoyancy of water causes an upward flow in the Fluorinert liquid 12, and the heat exchange of the refrigerator 11 arranged near the side wall. Since the vessel 9a produces a downward flow, a circulating flow of the Fluorinert liquid 12 is produced.

〔The invention's effect〕

As described above, according to the present invention, a storage part is provided at the bottom of the ice heat storage tank, and in this storage part, a Fluorinert liquid insoluble in water having a specific weight of 1.5 times or more and a freezing point of -50 ° C or less is added. It is stored and the temperature of this Fluorinert is kept at 0 ° C or lower by a refrigeration cycle. Also, the ice heat storage tank and the storage section are connected by piping, and the water in the ice storage tank is sprayed onto the Fluorinet solution in the storage section to form ice. Since it is deposited, it directly exchanges heat with the fluorinate liquid and the water mass, improves the heat exchange efficiency with the heat exchanger due to the circulating flow of the fluorinate liquid, increases the coefficient of performance of the refrigerator, and Since there is only water and ice in the storage tank, the filling rate of ice is high, and since the water mass (grains) is cooled by the Fluorinert liquid, the size of the ice that can be formed is small and the deicing performance is good, In addition, the system is simple and can be easily enlarged. A.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an ice heat storage device according to the present invention, FIG. 2 is a detailed diagram of a Fluorinert storage tank which is a cooling / ice depositing section,
FIG. 3 is a view showing another embodiment of the Fluorinert storage tank. 1 ... Ice heat storage tank, 2 ... Bottom part, 3 ... Side wall part, 4 ... Storage tank, 5 ... Rectifier plate, 9 ... Heat exchanger, 12 ... Fluorinert liquid, 13 ... Intake port, 15 ...... Nozzle, 16 ...... Piping, 20
...... Ice, 22 ...... interface.

Claims (4)

[Claims] 1. A storage unit is provided at the bottom of an ice heat storage tank, and the storage unit has a specific weight of 1.5 times that of water or more and a freezing point of -50.degree.
The following water-insoluble Fluorinert liquid is stored, and this Fluorinert liquid is kept at a temperature of 0 ° C or lower by a refrigeration cycle, and the ice heat storage tank and the storage unit are connected by pipes, and the water in the ice storage tank is stored in the storage unit. An ice heat storage device characterized by spraying the Fluorinert liquid of to deposit ice. 2. The ice heat storage device according to claim 1, wherein the reservoir is a liquid storage tank, a pipe is connected to the bottom of the liquid storage tank, and a check valve is provided in the pipe. 3. The ice heat storage device according to claim 2, further comprising a fluorinate liquid straightening plate for generating a circulating flow of the fluorinate liquid in the fluorinate liquid storage tank. 4. The ice heat storage device according to claim 2, wherein an inclined plate is provided at the bottom of the ice heat storage tank to collect the dispersed Fluorinert liquid in the liquid storage tank.