JPS63243665A - Cold-heat accumulating method utilizing ice - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is mainly aimed at smoothing the cooling load in the summer by storing cold heat generated by surplus nighttime electricity and releasing it for use during peak hours during the day. It is in.

[Prior art] As a conventional means for achieving the purpose of the Book of Proverbs, a refrigerator is used to cool the water filled in the aquarium, and when necessary, this cold water is circulated and used to cool the inside of the building. Air cooling is being done.

At this time, the water temperature increases as cold energy is used, so the cooling effect gradually decreases, and once a certain water temperature is reached, the effect is lost.

In practice, this temperature range is said to be 3 to 5 degrees Celsius, so when using the sensible heat of water in this way, the cold storage heat capacity fc (hereinafter referred to as cold storage capacity) is the maximum per liter of water stored in the tank. That's only about 3-5 Kcal.

In order to greatly increase the cold storage capacity, instead of using the sensible heat of water as described above, water undergoes a phase change between it and ice at 0°C, and during its solidification and melting, it is reduced to approximately 80 cal/l/h. kg
A cold storage method using latent heat that takes advantage of the fact that latent heat of H2O goes in and out is also widely used.

According to this method, even if 172 of the stored water is used as latent heat, a cold storage capacity of 40 Kcal/L is possible, which is about 10 times the 3 to 5 Kcal/L volume of the sensible heat utilization type. The cold storage that rises and is that much smaller
l! (hereinafter referred to as a cold storage tank), which has great value as an accessory equipment for air conditioning.

However, in this method, in order to solidify water into ice at 0°C, it is common to cool the water indirectly through the heat transfer surface of the heat exchanger, and in this case, the water phase side of the heat transfer surface is Since the heat transfer resistance increases due to the adhesion of ice, the temperature on the low temperature side of the heat transfer surface must be kept at -10 to -15℃ or lower in practice, and power consumption for cold storage is large. There was a drawback.

[Problems to be solved by the invention] When making ice by indirectly cooling water using a heat exchanger, freezing phenomenon on the heat transfer surface is unavoidable, and the heat transfer resistance is reduced by the ice layer. increases with increasing thickness. Therefore, in order to increase the VI heat rate of the heat storage tank and reduce power consumption, it is necessary to provide an extremely large heat transfer area.
This naturally accompanies an increase in setup costs.

The present invention aims to eliminate the drawbacks of conventional indirect cooling using a heat exchanger for cooling and freezing of water, by evaporating the water itself under reduced pressure and using its intense latent heat to self-cool the liquid and keep it below freezing. This produces ice.

Therefore, the conventionally used heat exchanger is no longer necessary, making it possible to significantly reduce equipment costs.

In addition, it is no longer necessary to provide a temperature difference of 10 to 20 degrees Celsius when heat is transferred through a heat transfer surface. This can help reduce Y4 costs.

However, in order to generate ice by self-cooling through water evaporation, the boiling point of water must be lowered to 0° C. or lower, and the system must be maintained at a reduced pressure of about 4 mnHg.

If all the water vapor obtained under these conditions were to be released into the atmosphere using a vacuum pump, it would require an extremely large-capacity vacuum pump and a large amount of power depending on the scale, and it would be impractical.

One possible means of condensing such steam under reduced pressure and drastically reducing the load on the vacuum pump is to cool the heat transfer surface of the heat exchanger to liquefy and condense the steam. However, in this case, the moisture must be condensed on the heat transfer surface at a temperature of at least 4 mHg or less and below 0°C, which may lead to freezing of the condensed water.

Therefore, in the direct cooling method under reduced pressure, by eliminating the cooling heat transfer surface in the heat storage tank, it is possible to avoid freezing on the surface, but when the generated water vapor condenses and liquefies, the heat transfer surface Troubles caused by ice formation on the pipes, such as reduced heat transfer capacity and blockage, are unavoidable.

[Means for Solving the Problems] The present invention utilizes the physicochemical properties of an aqueous solution containing a water-soluble and nonvolatile substance such as lithium bromide (LiBr).

The freezing point of an aqueous solution like the one mentioned above decreases depending on the concentration of the dissolved substance (solute), which is known as the freezing point depression phenomenon. /L, which is 1.86°C/ [: mol/L].

The boiling point of the above aqueous solution under constant pressure also increases depending on the concentration of solute (Cmol/L), which is known as boiling point elevation, and similarly, when the concentration is low, the degree of increase is 1'4. Regardless, it is proportional only to the concentration, and it is 0 near 0℃.
．． 25℃/Cmol/l.

These properties are found in all water-soluble inorganic and organic substances. In the present invention, solute selection conditions include solubility in water and flammability.

In addition to non-volatility under usage conditions, viscosity of the solution, invasiveness to equipment materials, etc., are important factors.

LiBr is one such selection example, and in the present invention, an antifreeze aqueous solution prepared by r4sing such a substance is referred to as a working fluid.

The present invention maintains a coexistence system of water and ice at approximately 4 mnHg during cold storage.
The resulting water vapor is boiled under the same pressure as the concentration of 1. The basic idea is to promote the formation of ice in the cold storage tank by absorbing it into the working fluid that has been cooled down.

In addition, the temperature of the working fluid in that state is 0℃ due to the rise in boiling point.
However, even if the temperature of the liquid in contact with the heat transfer surface is slightly o℃
The solution to this problem is to prevent the formation of ice from the liquid and the resulting ice formation on the heat transfer surface due to the drop in the freezing point, even if the temperature drops below this level.

Furthermore, the absorption heat of water vapor generated during absorption at such low temperatures is removed by evaporation of the refrigerant through the heat transfer surface, and this is used as a heating source by increasing the pressure and temperature by the compressor, and is diluted by water absorption. This is an i-J Yuru heat pump type absorption liquid that concentrates the working liquid. The reduction and regeneration method is considered an important means of energy conservation.

[For production] The operation of the present invention will be explained with reference to the drawings.

FIG. 1 is a flow sheet showing the operation of the present invention.

Reference numeral 1 denotes a cold storage tank, in which approximately 60 to 80% of the volume of water is present.

During cold storage, the inside of 1 is connected to a steam duct 2. Water vapor absorber 3
It is connected to a vacuum pump 6 via piping through the condensing side 4, and the pressure is reduced to about 4 an+Hg. The water boils under reduced pressure and is maintained at 0°C due to the latent heat of vaporization caused by the steam.

After that, the water continues to boil, but the latent heat of vaporization is offset by the heat of ice formation, and ice continues to form while the water temperature is maintained at 0°C, until 40 to 70% of the water inside 1 is occupied by ice. It comes to.

The main body of 3 is a heat exchanger, and 4 is provided with a heat transfer surface on the high temperature side. On the heat transfer surface, a concentrated liquid of the working liquid clears from the upper part and flows down while covering the heat transfer surface. The equilibrium water vapor pressure exhibited by the liquid is lower than the above-mentioned water vapor pressure of 1, and the difference serves as a driving force, and the water vapor is absorbed into the condensing liquid, gradually diluting the absorption liquid.

The heat of absorption generated in this case is removed by cooling by evaporation of the refrigerant on the cooling side 5 of 3, thereby making it possible to obtain the required water vapor absorption and therefore ice formation rate.

The generated diluted working liquid is transferred to a heat exchanger 8 by a diluted liquid pump 7.
The evaporated refrigerant vapor used for cooling is then sent to the heating side 11 of the condenser 9 after being pressurized and heated by the refrigerant compressor 13, where the heat of condensation is used for condensation. Becomes a heat source.

The refrigerant liquid condensed at 11 is returned to 5 through the expansion valve 14 and evaporated to remove the absorbed heat.

In this way, 5.13.11.14 are connected by piping to form a heat pump.

Provides an extremely powerful energy saving effect for cooling and heating the entire system.

9 has the same structure as 3, and lO is the 'aaIi part of the working fluid that has the heat transfer surface on the low temperature side.

Similar to 4, the diluted working fluid sent from 4 to 7 is heated from above and flows down while covering the surface.

10 is also connected via piping to a vacuum pump 17 via a water condenser 152 and a recovered water receiver 16.

Since No. 15 normally uses cooling water obtained from a cooling tower etc., the temperature of the condensed water vapor is around 35 to 40 degrees Celsius in the summer, and therefore the pressure of No. 10 is around 42°C.
Maintain ~55 mHga degrees.

The temperature of the working liquid flowing down 1O is determined by the t8 quality and 1a degree, but the liquid temperature gradually increases with concentration.

The liquid that has reached a predetermined degree of condensation in this way is pumped to the concentrate pump 12. It passes through the liquid-liquid heat exchanger 8 and returns to 4 again for circulation.

In this case, it is natural that the condensation temperature in step 11 is set higher than the liquid temperature corresponding to the degree of concentration to be achieved in step 10 to ensure the necessary amount of heat transfer.

The water collected in 16 is sent to water pump 1 as needed.
8 returns it to 1.

FIG. 1 is an example of a flow sheet used in carrying out the present invention, but other than that, partial changes may be made as necessary.
Or, by making additions, there is a possibility that the action and effect of the one-store invention can be enhanced.

In Figure 1, structures 3 and 9 are each provided with a heat transfer surface for heat exchange inside the vessel, and the working liquid is allowed to flow down in a laminar manner on one side, and the heat generated by water absorption or the heat absorption necessary for concentration is absorbed. By immediately removing or supplying the liquid with a refrigerant on the other side through the heat transfer surface, the main aim is to keep the flowing liquid as constant as possible in each vessel between them.

On the other hand, Fig. 2 is an advantageous method when circulating a relatively large amount of working fluid, and there is no heat transfer surface for heat exchange inside the chambers 3 and 9, and this is used in a spray tower or a gas-liquid system. It is constructed with a packed tower etc. for more effective contact.

A heat exchanger for pre-cooling or heating the working fluid supplied to the top of each tower is provided separately from the tower.

According to this process, the interior of 3.9 is operated adiabatically, and the necessary latent heat inside 3.9 is generated by the negative or positive sensible heat held by the working fluid at each inlet.
It is something that will be covered.

In addition, instead of the indirect heat exchange method using external cooling water as shown in No. 15, a known method called a barometric condenser is used to bring the cooling water and steam into direct contact in a depressurized tank and reduce the temperature difference. It is also possible to operate with a minimum.

Next, the means for improving the first function will be described.

Ice gradually forms and accumulates inside 1, but the density of the ice is 0℃.
Since it is small compared to water at 0.915 g/ce, it floats on the water surface and eventually becomes covered with a layer of ice. Under such conditions, water evaporation from the surface is significantly reduced, so it is necessary to prevent this.

For example, Figure 3 shows the blade 22 that stirs the ice layer that forms on the surface.
This method uses continuous mechanical crushing.

In Figure 4, the water layer at the bottom of 1 is pumped out with a circulation pump 23,
This is a method in which a hot liquid is applied to the entire surface of the ice layer from the separating tube 24, and water stone is constantly formed on the surface of the ice.

Of course, it is also possible to use the methods shown in FIGS. 3 and 4 in combination to ensure an effective evaporation surface for water.

FIG. 5 shows a method for further expanding the effective evaporation area of water.

Inside the tank 1, a large number of hanging frame cores 26 are arranged vertically at regular intervals in the tank.

26 has a planar mesh framework structure, has a surface area that almost occupies the cross section of 1, and is made to have sufficient strength.

The water remaining inside 1 is pumped out from the bottom by a circulation pump 23, passed through 24, and sprayed uniformly onto the upper end surface of each 26 arranged side by side from a spray nozzle 25, and is distributed to the lower liquid surface while covering the bottom surface. flowing towards.

Under these conditions, the flowing liquid boils under reduced pressure and freezes at 0°C due to its latent heat of vaporization.

In this way, adhering water 27 is gradually formed on the surface of 26, and the amount of residual water 28 decreases accordingly.

The amount of 27 attached will gradually increase and the distance between adjacent water surfaces will narrow, so the surface area of 26, mutual spacing, initial amount of 28, etc. are calculated in advance so that the generated water vapor can always be discharged out of the system through the gap. , Also, so that the amount of generated water that ultimately accumulates becomes the maximum value: A! The above is a description of the cold heat storage cycle, but there is no essential difference from the conventional ice-burning heat method in terms of the cycle in which the cold heat stored in the interior of 1 is released in this way.

In FIG. 1, the cold water pump 19 remains in the lower layer of 1.
After pumping out the water at ℃ and leading it to the cold load 20 and giving it a predetermined amount of cold heat, the heated water is returned to the water return line 21 through the water return line 21.
Return to 19.20, melt the remaining ice, discharge 80 kcal/- of cold heat stored in the ice, and cycle again at 19.20.

In this way, while the ice remains inside 1, the temperature of the water in contact with it is maintained at 0°C.

[Effects of the Invention] As explained above with reference to the drawings, the present invention has many advantages over conventionally known methods of ice valley cooling for generating and accumulating ice.

The first advantage is that the heat transfer coefficient is inferior to that of the conventional method, which uses water evaporation to achieve self-cooling by providing a heat exchange surface for indirect cooling, and generates ice on the heat transfer surface. It becomes possible to set a large temperature difference between the bottom and the heat transfer surface to compensate for this. This also helps reduce the power consumption of 13.

The second advantage is that by selecting an appropriate working fluid, it is possible to prevent the water vapor from freezing inside 3, which not only improves operational stability but also reduces the heat transfer coefficient of the heat exchanger and It is possible to prevent an increase in the temperature difference between 4.5 and 5.

This also results in a reduction in power consumption of 13.

The third advantage is that the cooling of the working fluid in step 3 and the concentration in step 9 are connected by a heat pump to form one thermal cycle.

This greatly contributes to reducing not only energy consumption but also equipment costs.

The fourth advantage relates to the structure and material of the cold storage tank.

According to the present invention, the side cooling tank only stores water and operates under reduced pressure, so a normal steel tank is sufficient, and there is no need to be subject to various legal regulations when using refrigerant under pressure. It's cheap. Set ii again! There are no restrictions on location.

Furthermore, by selecting a solute that does not cause any corrosion problems, such as additives constituting the working fluid, it is possible to select equipment materials that are inexpensive and have a long service life.

Furthermore, the fifth advantage is that the heat pump system used for cooling the working liquid when absorbing water evaporation and concentrating and heating the dilute working liquid uses a frequently used refrigerant such as R-12.
Using such a standard refrigeration system is extremely advantageous in terms of power efficiency and equipment costs. Also 3,
In No. 9, the refrigerant system and working fluid system are isolated from each other in terms of heat transfer, so there is no chance of moisture entering the refrigerant system, and there is no risk of loss of refrigerant or corrosion of refrigeration cycle components. be.

[Example 1] An aqueous solution of L i Br was used as the working liquid, and valley cooling with ice was performed according to the method shown in FIG. 1 .

The biBra degree of the aqueous solution supplied to No. 4 was set to about 20% (M ratio).

During cold storage, the pressure inside 1 was first reduced to about 4 maHH using 6, and the water was boiled and evaporated while gradually cooling down.

The evaporated steam was sent to the condensing side 4 from 2 to 3, and was absorbed by the working liquid having a concentration of about 20% (M ratio) flowing down from the upper part on the heat transfer surface provided inside.

After a slight supercooling, the water temperature returned to around 0%, and ice crystals were produced, and as evaporation continued, the volume of the water increased, but at this time the pressure of 1 could be maintained at about 4 m1 (H). did it.

Furthermore, by installing a means as shown in FIGS. 3 and 4 inside the container 1, it was possible to prevent the surface from being completely covered with ice.

Ice was deposited at about 40 to 60% of the amount of water charged, but there was no particular problem, and no decrease in evaporation or opening of pipes due to ice formation was observed.

The concentration of the working liquid exiting the cooling tank decreases to about 10.5% due to water absorption, but the refrigerant evaporation temperature in the cooling can is maintained at around -5°C, providing the temperature difference necessary for cooling the working liquid. Ta.

No precipitation of ice or dissolved salts from the working fluid was observed.

The recovered working liquid is sent to the evaporation side 1o of 9, and is heated by the R-12 vapor condensed at about 53° C. on the heating side II while flowing down the heat transfer surface provided inside.

IO is 15. IG, connected to +7, approximately 55mm 1g
was maintained under reduced pressure.

In this way, the approximately 10.5% working liquid begins to boil at approximately 46°C and does not flow down the heat transfer surface, so that the approximately 10.5% working liquid begins to boil at approximately 46°C and does not flow down the heat transfer surface.
It is concentrated to 0% and returned to 4.

The generated water vapor is cooled by cooling water at 15,
After being condensed and recovered at about 40°C, it was returned to 1 at 18°C.

Heat exchangers were installed as appropriate for the circulation of working fluid and recovered water to improve thermal efficiency.

The @ring system of R-12 was prepared using a screw refrigerator using a conventional freezing technique.

The efficiency is 1 ice production including heat loss of the whole system and mechanical efficiency.
The power output was approximately 42kW per ton, and the COP was approximately 2.2.

[Brief explanation of drawings]

FIG. 1 is an example of a flow sheet for explaining a cooling method using ice. Figure 2 is a part of a flow sheet showing a method to separate the heat exchange functions 3 and 9 and the mass transfer function of absorbing and evaporating water vapor, which are integrated in Figure 1. be. FIGS. 3 and 4 are diagrams showing a method of constantly exposing a wide water surface by crushing the water surface formed on the surface of the water layer or by sprinkling water on the surface, respectively. FIG. 5 is a diagram showing an example of means for providing a large frozen area inside the container 1. The symbols in each figure are common and are as follows.

Claims (1)

[Scope of Claims] 1. Water is stored in a cold storage tank 1, and when storing water, it is boiled under reduced pressure, the liquid is self-cooled, and ice is generated at a temperature below 0°C to remove water vapor that evaporates during cold storage. The heat of absorption generated by being absorbed by the concentrated antifreeze aqueous solution (hereinafter referred to as working liquid) introduced into the condensing side 4 of the steam absorber 3 is removed by the evaporation of the refrigerant on the cooling side 5, and the obtained refrigerant vapor is converted into a refrigerant. The compressor 13 raises the pressure and temperature, and sends it to the heating side 11 of the concentrator 9, where it is condensed and used as a heating source, while the diluted working liquid is sent to the evaporation side 10 of 9, where it is evaporated and concentrated under reduced pressure. ,
The obtained refrigerant liquid and the concentrated working liquid are appropriately returned to 5 and 4, respectively.Cold storage heat method using ice 2, Claim 1 includes a plurality of planar hanging frames inside 1. The wick 26 is suspended, and the remaining water inside is pumped out by the circulating water pump 23, and the upper end of the wick 26 is uniformly watered through the liquid separation pipe 24 and the Slay nozzle group 25, and as the water flows down the surface of the wick 26, , a cold storage heat method using ice, characterized by self-cooling by evaporating a part of it, and freezing a part of it on the flowing surface.