JP2001033069A - Thermal storage system and melting method in the thermal storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To circulate bubbles upward along the outer surface of a heat transfer portion in a liquid cold storage medium while generating a forcible flow and turbulence in the surrounding liquid cold storage medium, improve heat transfer performance of the outer surface of the heat transfer portion and accelerate heat recovery from a heat storage tank, by providing a bubble blow-off portion for supplying bubbles in the liquid cold storage medium between the outer surface of the heat transfer portion and a solid cold storage medium covering the heat transfer portion. SOLUTION: A system comprises a heat storage tank 1 filled with a cold storage medium 2, a heating tube 3 which is disposed in the tank 1 for exchanging heat between refrigerant and the cold storage medium 2 in the tank 1, a bubble blow-off portion 4 which is disposed at a lower portion in the tank 1 and has air blow-off holes 5, a compressed air generating and supplying device 6 for supplying compressed air to the bubble blow-off portion 4, and a heat source unit 7 and a load side unit 8 both connected to the heating tube 3. The bubble blow-off portion 4 is provided to supply bubbles to a liquid cold storage medium between the outer surface of the heating tube 3 and a solid cold storage medium covering the heating tube 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage system for melting a solid heat storage refrigerant attached around a heat transfer tube typified by an internal melting type heat storage system, and to a heat storage system capable of performing the melting efficiently and a melting method thereof. Things.

[0002]

2. Description of the Related Art FIG. 24 shows an apparatus diagram disclosed in Japanese Utility Model Laid-Open No. 3-18439, for example, as a conventional example of a method of blowing bubbles from a lower part of a heat storage tank in a melting operation of a heat storage system.

In FIG. 24, 1 is a heat storage tank which is an ice heat storage tank, 3a to 3c are heat transfer sections formed of heat transfer tubes, 6 is a pressurized gas generating / supplying device forming bubble generating means, 4 is a bubble blowing pipe,
14 is a circulation pump which is a water pump, 15 is a temperature detecting means, 8 is a load side unit which is a heat exchange means with the load side,
19 is a water flow pipe, and 16 and 17 are air bubble amount adjusting means.

Next, an operation example will be described with reference to FIG. In order to keep the temperature detecting means 15 constant, a bubble amount control signal is transmitted from the bubble amount adjusting means 16 and 17 to the pressurized gas generation and supply device 6, and the bubble amount generated from the lower part of the heat storage tank is adjusted. Due to the blowing of bubbles from the lower part of the heat storage tank, the upper and lower temperature distributions of the cold water in the heat storage tank 1 disappear, and as a result,
Ice adhering around the heat transfer section 3 is uniformly melted.

As a conventional example of a method of blowing a pressurized liquid from a lower part of a heat storage tank in a melting operation of a heat storage system, an apparatus shown in, for example, Japanese Patent Application Laid-Open No. 5-215370 is shown in FIG.
Shown in

In FIG. 25, 1 is a heat storage tank which is an ice heat storage tank, 2 is a heat transfer section comprising a heat transfer tube, 14 is a circulation pump,
Reference numeral 4 'denotes a pressurized liquid jet pipe as a water jet pipe, reference numeral 18 denotes a water flow branch pipe, reference numeral 6' denotes a pressurized liquid generation / supply device as a water pump, and reference numeral 8 denotes a load-side unit serving as load-side cooling equipment.
Incidentally, the refrigerant medium is water.

Next, an operation example will be described with reference to FIG. During the cold storage operation, a refrigerant having a temperature lower than the freezing temperature of water is circulated through the heat transfer unit 3 and the pressurized liquid generation and supply device 6 'is continuously operated to add a part of the cold water in the heat storage tank 1. Water is sent to the pressurized liquid jet pipe 4 '. Then, the open / close valves FA are sequentially opened for 5 minutes by the timer, and pressurized water is intermittently blown out from the pressurized liquid jet pipe 4 '.

[0008] Since the temperature of the cold water in the heat storage tank 1 becomes substantially uniform over the entirety by the pressurized water blowing from the lower part of the heat storage tank, the thickness of ice generated around the heat transfer section 3 becomes substantially uniform over the whole.

On the other hand, during the melting operation, the circulating pump 14 is operated to send cold water in the heat storage tank 1 to the load side, and then circulates to the heat storage tank 1. At this time, the pressurized liquid generating / supplying device 6 'is operated to pressurized water from the pressurized liquid jet pipe 4' intermittently for 5 minutes each as in the case of ice making.

[0010] Due to the blowing of pressurized water from the lower part of the heat storage tank, the temperature distribution between the upper and lower portions of the cold water in the heat storage tank 1 disappears, and the ice adhering around the heat transfer part 3 is uniformly melted.

[0011]

In any of the above cases, the melting method is an external melting method, and the purpose of blowing out bubbles and pressurized liquid is as follows.
Eliminates uneven temperature of the liquid refrigerant in the heat storage tank, especially when a solid refrigerant is present, supplying the liquid refrigerant to the load side while always maintaining the melting temperature of the refrigerant, The purpose is to melt the medium from the outside and make the degree of melting uniform throughout the vessel.

[0012] For this reason, the promotion of melting of the solid storage refrigerant at a specific position or area in the heat storage tank, the use of the solid storage refrigerant in an internal melting type heat storage system, and the improvement of the heat transfer performance of the heat transfer section surface are not described. Not considered.

An object of the present invention is to improve the heat transfer performance of the heat transfer section surface by supplying bubbles or pressurized liquid to a specific position or area.

[0014]

A heat storage system according to the present invention exchanges heat between a heat storage tank filled with a refrigerant storage medium and a refrigerant installed in the heat storage tank and the refrigerant storage medium in the heat storage tank. A heat transfer unit, a bubble blowing unit provided in the lower part of the heat storage tank and having a gas blowing hole, a pressurized gas generation / supply unit for supplying a pressurized gas to the bubble blowing unit, and a connection to the heat transfer unit A heat source unit and a load side unit,
The bubble blowing section is provided so as to supply bubbles into the liquid refrigerant between the heat transfer section outer surface and the solid refrigerant storing the heat transfer section.

Further, the heat transfer section is a heat transfer fin.

Further, the heat transfer fin is a plate-like fin,
A plurality of bubble blowing holes are made to correspond to one surface of one plate-like fin.

Further, the pressurized gas generation / supply section controls the amount of bubbles blown into the liquid storage medium.

Further, the present invention provides an internal melting type heat storage system including a heat source unit and a load side unit connected to the heat transfer unit via a refrigerant pipe.

[0019] Further, in the cold storage operation, the refrigerant is not circulated through the internal refrigerant flow passage, but is provided with a heat transfer section dedicated to melting for flowing a refrigerant having a temperature equal to or higher than the melting temperature of the storage medium only during the melting operation.

Further, the bubble blowing section is provided so as to supply bubbles into a liquid refrigerant storage medium between the outer surface of the heat transfer section dedicated for melting and the solid refrigerant storage section covering the heat transfer section dedicated for melting.

Further, the gas outlet is disposed below the outer surface of the heat transfer section.

Further, the gas blowout hole and the lower portion of the outer surface of the heat transfer section are brought into contact with or close to each other.

Further, the heat transfer portion is a cylindrical tube, and the gas blowout hole is provided immediately below or near the heat transfer tube.

Also, a pressurized liquid blowout unit having a pressurized liquid blowout hole formed therein instead of the bubble blowout unit is provided with a pressurized liquid generation and supply unit instead of the pressurized gas generation and supply unit.

[0025] An apparatus for fixing the lower portion of the heat transfer section in the heat storage tank is provided, and the apparatus is the bubble blowing section or the pressurized liquid blowing section.

In addition, a liquid pump for circulating a refrigerant is provided between the heat transfer section in the heat storage tank and the load side unit.

The pH of the liquid storage medium in the heat storage tank is
And a PH controller for controlling the PH value of the liquid storage medium in accordance with the detection result of the PH detector.

In addition, a solid-state refrigerant is generated in the heat storage tank during a first predetermined time period, and the solid-cooled storage medium in the heat storage tank is generated during a second predetermined time period that is not continuous with the first predetermined time period. The apparatus is provided with a peak cut means that covers the cooling load on the load side only by the cooling heat that is obtained by melting and recovering the medium.

Further, in the method for melting a heat storage system according to the present invention, the flow of the liquid heat storage medium is promoted by passing bubbles through the liquid heat storage medium between the surface of the heat transfer section and the solid heat storage medium. Improve the heat transfer performance of the part surface.

Further, the amount of melting is adjusted by controlling the amount of bubbles blown into the liquid refrigerant.

In addition, a pressurized liquid is passed instead of bubbles.

Further, during the peak cut operation which is not continuous with the generation of the solid refrigerant, bubbles or pressurized liquid are passed.

Further, the heat storage system according to the present invention includes a heat storage tank filled with a refrigerant storage medium, and a heat transfer unit installed in the heat storage tank and exchanging heat between the refrigerant and the refrigerant storage medium in the heat storage tank. A bubble blowing unit provided at a lower portion in the heat storage tank and having a gas blowing hole, a pressurized gas generation / supply unit for supplying a pressurized gas to the bubble blowing unit, and a heat source unit connected to the heat transfer unit And a load-side unit, wherein a cover is formed on the outer surface of the heat transfer section, and the bubble blowing section is provided so as to supply bubbles into the liquid refrigerant between the heat transfer section and the cover.

Further, the cover is formed of a solid storage refrigerant.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a schematic diagram of the heat storage system of the first embodiment, and FIG. 2 is a cross-sectional view of the heat storage tank of the first embodiment. 1 and 2, 1 is a heat storage tank whose upper part is not completely sealed, 2 is a refrigerant storage medium filled in the heat storage tank 1, and 3 is a heat storage tube provided in the heat storage tank 1 and immersed in the refrigerant storage medium. The heat transfer unit 4 is a bubble blowing tube which is a bubble blowing unit disposed in the lower part of the heat storage tank 1, 5 is a bubble blowing hole provided on the bubble blowing tube 4, and 6 is a pressurized gas ( Pressurized gas generation and supply device for supplying air)
Is a heat source unit, 8 is a load unit, and the heat source unit 7
And the load unit 8 constitute a refrigeration cycle, and a heat transfer tube connecting the heat source unit 7 via the heat transfer unit 3 branches from the middle of one of the heat transfer tubes connecting the heat source unit 7 and the load unit 8. An electronic expansion valve is provided in a heat transfer tube between the heat transfer unit 3 and the heat transfer tube.

Next, the operation of the melting operation will be described with reference to FIG. When a refrigerant having a temperature higher than the melting temperature of the refrigerant body 2 flows from the load side unit group 8 or from the heat source unit 7 into the refrigerant flow passage inside the heat transfer unit 3, solids formed around the outer surface of the heat transfer unit 3 are generated. The refrigerant body 2b melts sequentially from the inside. At this time, the refrigerant flowing through the heat transfer section 3 performs a condensing action and releases heat. The melting of the refrigerant body 2 is melted from the innermost part of the solid refrigerant body 2b attached to the heat transfer section 3 to become a liquid, and the liquid refrigerant body 2a exists between the outer surface of the heat transfer section 3 and the solid refrigerant body 2b. start. When a pressurized gas is generated by the pressurized gas generation and supply device 6 during the melting operation, and bubbles are blown out from the bubble blowing holes 5 through the bubble blowing pipe 4, the bubbles are irregularly and minutely dispersed in the liquid storage medium 2a by buoyancy. It rises along the outer surface of the heat transfer section 3 with vibration. FIG. 3 shows a schematic diagram of the bubble blowing.

When air bubbles flow along the outer surface of the heat transfer section 3 in the liquid storage medium 2a sandwiched between the outer surface of the heat transfer section 3 and the solid storage medium 2b, the liquid storage medium 2a moves in a direction perpendicular to the bubble traveling direction. Is a closed space, and when bubbles with irregular movements flow through it, the liquid refrigerant 2a near the outer surface of the heat transfer section 3
Also, forced flow and turbulence are generated under the influence of air bubble distribution. As a result, a heat transfer effect is generated on the outer surface of the heat transfer section 3 more than when natural convection heat transfer is dominant, such as forced convection heat transfer. At this time, the bubble rises as a passage between the heat transfer section 3 and the solid refrigerant body covering the heat transfer section 3, so that the bubble is higher than that of the conventional external melting type which simply generates bubbles in the heat storage tank. Can be sent to a desired position or area, and the heat transfer efficiency is improved. The solid storage medium gradually melts and the distance between the heat transfer tube 3 and the heat transfer tube 3 increases. However, since the relative position between the heat transfer tube 3 and the bubble blowing hole 5 does not change, the action of bubbles passing through the surface of the heat transfer tube 3 is maintained. Is done.

The amount of heat recovered from the heat storage tank 1 during the melting operation can be expressed by equation (1), and the heat transfer coefficient K representing the heat transfer performance of the heat transfer section can be expressed by equation (2). Q = Ao · K · ΔT Equation (1) Q: Heat recovery amount [W] Ao: Heat transfer tube outer area [m ² ] K: Heat transfer tube heat transmittance [W / m ² K] ΔT: Heat transfer inside the heat transfer section Temperature difference between the refrigerant and the refrigerant in the heat storage tank [K] 1 / K = (1 / αo + Ao / Ai / αi) Equation (2) αo: Heat transfer coefficient of heat transfer unit outer surface [W / m ² K] αi : Heat transfer coefficient on the inner surface of the heat transfer section [W / m ² K] Ai: Area of the refrigerant flow section in the heat transfer section [m ² ] From the equation (1), when Ao and ΔT are constant, the larger the value of K is, the more the heat recovery. The quantity Q increases, and from equation (2), αi,
It can be seen that when Ao and Ai are constant, the heat transfer rate K of the heat transfer section 3 increases as αo increases.

By the flow of bubbles on the outer surface of the heat transfer section 3, the equation (3)
Since the heat transfer coefficient αo of the outer surface of the heat transfer unit 3 increases, the heat transfer rate K of the heat transfer unit 3 also increases, and as a result, the amount of heat recovery Q from the heat storage tank 1 per unit time of the equation (2) increases. can do.

Further, when the bubble blowing holes 5 are close to the outer surface of the heat transfer section 3, the probability of flowing bubbles to the liquid refrigerant medium 2a where the bubbles are to flow between the outer surface of the heat transfer section 3 and the solid heat storage medium 2b is increased. Since bubbles can be efficiently blown out, the heat transfer performance of the outer surface of the heat transfer unit 3 is improved, and the amount of heat recovered from the heat storage tank 1 per unit time can be increased.

In the case where the bubble blowing holes 5 are uniformly installed on the entire lower part of the heat storage tank 1 without considering the position of the heat transfer section, the liquid storage medium 2a between the outer surface of the heat transfer section 3 and the solid heat storage medium 2b is provided.
Air bubbles that do not circulate are generated, the amount of circulating air bubbles is reduced, and the degree of improvement in the heat transfer performance of the outer surface of the heat transfer unit 3 is small. On the other hand, bubbles that do not flow through the liquid refrigerant 2a between the outer surface of the heat transfer section 3 and the solid heat storage medium 2b flow through the outer surface of the solid refrigerant 2b, and the outside of the solid refrigerant 2b is owed to the sensible heat owned by the bubbles themselves. A phenomenon occurs in which the latent heat is lost due to unnecessary melting. A schematic diagram is shown in FIG. Considering the heat transfer performance improvement efficiency, one gas blowout hole 5 is made to correspond to the liquid storage medium 2a between the outer surface of one heat transfer part 3 and the solid heat storage medium 2b, so that the blown air bubbles are surely removed from the liquid. Cooling medium 2
I want to send it to the limited gap of a.

When the bubble blowing pipe 4 is once connected to the gas pressurized gas generating / supplying device 6 via the side surface of the heat storage tank 1 as shown in FIG. Since it is not necessary to make a hole, the heat storage tank 1 can be diverted to another use such as a dynamic ice heat storage tank. Moreover, the upper surface cover of the heat storage tank 1 is not covered by welding but is put on a cover, and is detachable. As described above, the processing operation and the disassembly operation are simplified, and can be diverted to another use.

Next, the effect of improving the heat transfer performance of the blowing of bubbles during the melting operation will be quantitatively described based on actual results. Fig. 6 shows the installation of a cylindrical heat transfer tube in the vertical direction in the heat transfer section, using water as the refrigerant medium and a 40% ethylene glycol solution as the refrigerant flowing through the heat transfer section, and setting the heat transfer tube refrigerant inlet temperature to 5 ° C. It is an experimental result in the case of doing. The average heat transfer coefficient outside the tube was about five times that in the case with and without bubble blowing, indicating that the heat transfer performance outside the tube was greatly improved by the bubble blowing.

(1) Immediately after the start of melting The solid refrigerant is melted to become a liquid refrigerant, but the thickness of the liquid portion is thin, and the bubbles do not enter the liquid refrigerant well, so that the bubbles flow on the outer surface of the heat transfer tube. do not do. In this case, the heat transfer is dominated by the heat conduction of the liquid storage medium. Equation (3) shows the equation of the heat transfer coefficient dominated by heat conduction. α = λ / L Equation (3) α: Heat transfer coefficient [W / m ² K] λ: Heat conductivity [W / mK] L: Thickness of liquid part [m] Thermal conductivity is a physical property value, and It is a value uniquely determined by the type, temperature, etc. For example, in the case of water, λ = 0.562 [W /
mK] (at 0 ° C.), and if the thickness L = 0.5 cm = 5.0e−3 [m], α = 112 [W / m ² K], which is a low value from equation (3). Further, from the equation (3), it can be seen that as the melting proceeds, the amount of the liquid storage medium and the thickness of the liquid portion increase, so that the heat transfer coefficient on the outer surface of the heat transfer tube decreases.

(2) When air bubbles start flowing on the outer surface of the heat transfer tube When the amount of liquid refrigerant and the thickness of the liquid portion increase, natural convection heat transfer becomes dominant in heat transfer due to heat conduction. At this time, when air bubbles start to flow along the outer surface of the heat transfer tube in the liquid storage medium,
Flow or turbulence occurs at a speed higher than natural convection generated by the temperature difference of the liquid storage medium itself. As a result, a heat transfer effect equivalent to forced convection occurs on the outer surface of the heat transfer section, and the amount of heat recovery from the heat storage tank per unit time can be increased.

FIG. 6A shows the results of a melting operation experiment when no bubbles are blown out. In this case, natural convection occurs in the vertical direction due to the density difference in the liquid refrigerant between the outer surface of the heat transfer part and the solid refrigerant, and the heat transfer coefficient αo = 150 [W / m ² K]. On the other hand, FIG. 6B shows the results of a melting operation experiment in the case where air bubbles are blown out. In this case, the heat transfer performance is improved by the influence of the flow and turbulence caused by the flow of bubbles on the outer surface of the heat transfer portion. From FIG. 6B, it can be estimated that the heat transfer coefficient αo = 790 [W / m ² K].

For example, heat transfer area Ao = Ai = 1 [m ² ],
Assuming that the heat transfer coefficient on the inner surface of the heat transfer tube αi = 2000 [W / m ² K] and the temperature difference ΔT = 5 [deg] between the refrigerant and the refrigerant, the amount of heat recovery from the heat storage tank with and without bubble blowing is estimated. [When there is no bubble blowing] K = (1/150 + 1/2000) -1 = 140 [W / m ² K] Equation (4) Q = Ao · K · ΔT = 1 · 140 · 5 = 700 [W] Equation (5) [When there is bubble blowing] K = (1/790 + 1/2000) -1 = 566 [W / m2K] Equation (6) Q = Ao · K · ΔT = 1 · 566.5 = 2830 [W] Equation (7), and the amount of heat recovered from the heat storage tank at the time of bubble blowing is about four times that when no bubble is blown.

As described above, if the internal melting type heat storage system shown in the first embodiment is used, a bubble blowing hole is provided in the liquid storage medium between the outer surface of the heat transfer section and the solid state storage medium, so that the heat storage can be performed during the melting operation. The pressurized gas is generated by the pressurized gas generator, and the bubbles are blown out from the bubble blowing holes through the bubble blowing pipe. Since the bubbles flow upward while generating turbulence, the heat transfer performance of the outer surface of the heat transfer unit is improved, and the amount of heat recovery from the heat storage tank per unit time can be increased.

Embodiment 2 FIG. 7 is a schematic diagram of a heat storage system according to Embodiment 2, and FIG. 8 is a diagram of a heat storage tank. In the figure, 1 is a heat storage tank, 2 is a refrigerant storage body, 3 is a flat heat transfer section, 4 is a bubble blowing tube, 5 is a bubble blowing hole, 6 is a pressurized gas generation and supply device, 7 is a heat source unit, 8 is In the load units, these correspond to the same reference numerals in the first embodiment.

The operation of the melting operation will be described with reference to FIGS. When a refrigerant having a temperature higher than the melting temperature of the refrigerant body 2 flows from the load side unit group 8 or from the heat source unit 7 into the refrigerant flow passage inside the heat transfer unit 3, the solid cold storage generated and attached to the outer surface of the heat transfer unit 3. The medium 2b melts sequentially from the inside. At this time, the refrigerant flowing through the heat transfer section 3 performs a condensing action and releases heat. The refrigerant 2 is melted from the innermost part of the solid refrigerant 2b adhering to the outer surface of the heat transfer unit 3 to become liquid, and the liquid refrigerant 2a exists between the outer surface of the heat exchanger 3 and the solid refrigerant 2b. Begin to. When the pressurized gas is generated by the pressurized gas generator 6 during the melting operation and the bubbles are blown out from the bubble blowing hole 5 through the bubble blowing pipe 4, the bubbles randomly and minutely vibrate in the liquid storage medium 2a by buoyancy. With this, it rises along the outer surface of the heat transfer section 3. FIG. 9 is a schematic diagram of the bubble blowing.
Shown in

When air bubbles flow along the outer surface of the heat transfer section 3 in the liquid storage medium 2a sandwiched between the outer surface of the heat transfer section 3 and the solid refrigerant medium 2b, the liquid refrigerant 2a moves in a direction perpendicular to the bubble traveling direction. Is a closed space, and when bubbles with irregular movements flow through it, the liquid refrigerant 2a near the outer surface of the heat transfer section 3
Is also affected by the flow of air bubbles, causing forced flow and turbulence. As a result, a heat transfer effect, such as forced convection heat transfer, is exerted on the outer surface of the heat transfer section 3 more than when natural convection heat transfer is dominant. still,
When the heat transfer section 3 is a flat plate, the liquid storage medium 2a between the outer surface of the heat transfer section 3 and the solid storage medium 2b becomes wider horizontally, and a plurality of bubble blowing holes 5 are formed in one gap of the liquid storage medium 2b. Therefore, even if clogging occurs in one of the bubble blowing holes 5, bubbles blown from the other holes flow through the liquid storage medium 2a, so that the reliability of performance improvement as a system is improved. I do.

When the bubble blowing hole 5 is close to the outer surface of the heat transfer section 3, the probability of flowing bubbles to the liquid refrigerant 2a where the bubbles are desired to flow between the outer surface of the heat transfer section 3 and the solid heat storage medium 2b is increased. Since air bubbles can be well blown out, the heat transfer performance of the outer surface of the heat transfer unit 3 is improved, and the heat storage tank 1 per unit time is improved.
The amount of heat recovered from the fuel can be increased.

As described above, if the internal fusion type heat storage system described in the second embodiment is used, a bubble blowing hole is provided in the liquid storage medium between the outer surface of the heat transfer section and the solid storage medium, so that the heat storage can be performed during the melting operation. The pressurized gas is generated by the pressurized gas generator, and the bubbles are blown out from the bubble blowing holes through the bubble blowing pipe. Since the bubbles flow upward while generating turbulence, the heat transfer performance of the outer surface of the heat transfer unit is improved, and the amount of heat recovery from the heat storage tank per unit time can be increased. In addition, since the heat transfer section has a flat plate shape, a plurality of bubble outlets are made to correspond to one liquid refrigerant between the outer surface of the heat transfer section and the solid refrigerant, so that clogging is caused by one of the bubble outlets. Even if it occurs, there is an advantage that the heat transfer performance is not significantly reduced.

Embodiment 3 FIG. FIG. 10 is a diagram of a heat storage tank according to the third embodiment. In the figure, 1 is a heat storage tank, 2 is a refrigerant storage body, 3 is a vertical cylindrical heat transfer tube, 4 is a bubble blowing tube, 5 is a bubble blowing hole, 6 is a pressurized gas generation and supply device, 7 is a heat source unit, and 8 is a load. In the unit, these correspond to the same reference numerals in the first embodiment.

In the case where the solid refrigerant body 2b is prevented from being generated, for example, a heat insulating material is provided below the heat transfer section 3,
The operation when there is a distance between the bubble blowing hole 5 and the lower part of the heat transfer section 3 will be described with reference to FIG. When a refrigerant having a temperature higher than the melting temperature of the refrigerant body 2 flows from the load side unit group 8 or from the heat source unit 7 into the refrigerant flow passage inside the heat transfer unit 3, solids formed around the outer surface of the heat transfer unit 3 are generated. The refrigerant body 2b melts sequentially from the inside. At this time, the refrigerant flowing through the heat transfer section 3 performs a condensing action and releases heat. The melting of the cooling medium 2 is melted from the innermost part of the solid cooling medium 2b attached to the heat transfer tube to become a liquid, and the liquid cooling medium 2a starts to exist between the outer surface of the heat transfer unit 3 and the solid cooling medium 2b. When the pressurized gas is generated by the pressurized gas generator 6 during the melting operation and the bubbles are blown out from the bubble blowing hole 5 through the bubble blowing pipe 4, the bubbles randomly and minutely vibrate in the liquid storage medium 2a by buoyancy. With this, it rises along the outer surface of the heat transfer section 3.
FIG. 11 shows a schematic diagram of the bubble blowing.

When there is a distance between the bubble blowing hole 5 and the lower portion of the heat transfer section 3, as much as possible of the blown out bubbles, the liquid refrigerant 2a sandwiched between the outer surface of the heat transfer section 3 and the solid refrigerant 2b.
In order to feed the air into the inside, the bubble blowing hole 5 is provided directly below the heat transfer section 3 or in the vicinity thereof. When the bubbles flow through the liquid storage medium 2a, the liquid storage medium 2a is affected by the flow of the bubbles, because the liquid storage medium 2a has a limited gap, and the bubbles having irregular movements flow through the space. Flow and turbulence occur. As a result, a heat transfer effect equivalent to forced convection occurs on the outer surface of the heat transfer unit 3, and the amount of heat recovered from the heat storage tank 1 per unit time can be increased.

When the bubble blowing hole 5 is close to the outer surface of the heat transfer section 3,
Since the probability that air bubbles flow through the liquid refrigerant 2a where the air bubbles between the outer surface of the heat transfer unit 3 and the solid heat storage medium 2b are desired to flow can be increased and the air bubbles can be efficiently blown out, the heat transfer on the outer surface of the heat transfer unit 3 can be performed. The performance is improved, and the amount of heat recovered from the heat storage tank 1 per unit time can be increased.

As described above, if the internal fusion type heat storage system shown in the third embodiment is used, a bubble blowing hole is provided in the liquid storage medium between the outer surface of the heat transfer section and the solid storage medium, so that the heat storage can be performed during the melting operation. The pressurized gas is generated by the pressurized gas generator, and the bubbles are blown out from the bubble blowing holes through the bubble blowing pipe. Since the bubbles flow upward while generating turbulence, the heat transfer performance of the outer surface of the heat transfer unit is improved, and the amount of heat recovery from the heat storage tank per unit time can be increased. In addition, if there is a distance between the bubble outlet and the lower part of the heat transfer section, the bubble outlet is required to send as many blown bubbles as possible into the liquid refrigerant between the outer surface of the heat transfer tube and the solid refrigerant. When installed immediately below or near the bottom of the heat transfer tube, the bubbles rise upward due to buoyancy, and therefore have the highest probability of flowing through the liquid refrigerant.

Embodiment 4 FIG. FIG. 12 is a diagram of a heat storage tank according to the fourth embodiment. In the figure, 1 is a heat storage tank, 2 is a refrigerant storage medium, 3a is a heat transfer section that circulates a refrigerant through an internal refrigerant circulation section in both the cold storage operation and the melting operation and performs ice generation and ice melting, and 3b is an internal refrigerant only during the melting operation. A heat transfer section dedicated to melting for flowing the refrigerant through the flow section, 4 is a bubble blowing pipe, 5 is a bubble blowing hole, 6 is a pressurized gas generation and supply device, 7 is a heat source unit, and 8 is a load unit. 1 corresponds to the same reference numeral.

The operation of the melting operation will be described with reference to FIG. When a refrigerant having a temperature higher than the melting temperature of the refrigerant body 2 flows through the refrigerant flow passage inside the heat transfer part 3a, the solid refrigerant body 2b present around the outer surface of the heat transfer part 3 is melted sequentially from the inside. At this time, the refrigerant flowing through the heat transfer section 3 performs a condensing action and releases heat. On the other hand, since the heat transfer section 3b is not used during the cold storage operation, the solid coolant 2
b does not adhere and the liquid storage medium 2a is present around it. When a refrigerant having a temperature higher than the melting temperature of the refrigerant storage medium 2 flows through the refrigerant flow passage inside the heat transfer unit 3a during the melting operation, the refrigerant storage medium 2
And heat exchange using the sensible heat of the refrigerant storage medium 2.

The amount of heat recovered from the heat storage tank 1 during the melting operation can be expressed by equations (8) and (9). When the heat transfer unit 3b dedicated for melting is added, the area of the heat transfer unit 3 increases by Aob [m2], and the heat recovery amount increases accordingly. -When there is no heat transfer section dedicated to melting Qa = Aoa · Ka · ΔT equation (8)-When there is a heat transfer section dedicated to melting Qb = (Aoa · Ka + Aob · Kb) · ΔT equation (9) Aoa: Heat transfer section 3a Outer surface area [m ² ] Aob: Heat transfer part 3b Outer surface area [m ² ] Ka: Heat transfer rate of heat transfer part 3a [W / m ² K] Kb: Heat transfer rate of heat transfer part 3b [W / m ^2] K] ΔT: Temperature difference between the refrigerant flowing inside the heat transfer section and the refrigerant storage medium [K] Comparing Equations (8) and (9), the amount of heat recovery increases by Aob · Kb.

As shown in FIG. 12, when there is no bubble blowing tube 4 and bubble blowing hole 5 inside the heat storage tank 1 and no gas pressurizing and supplying device 6 in the heat storage system, the outer surfaces of the heat transfer sections 3a and 3b are formed. In the heat transfer, natural convection is dominant and both have the same performance. Ka and Kb in equation (4) are equivalent.

As shown in FIG. 13, a bubble blowing hole 5 is provided in the liquid storage medium 2a between the outer surface of the heat transfer section 3a and the solid storage medium 2b, a bubble blowing pipe 4 is provided in the heat storage tank 1, and a gas is provided in the heat storage system. A pressurizing / supplying device 6 is provided to blow air bubbles during the melting operation, while a bubble blowing tube 4 and a bubble blowing hole 5 are provided on the heat transfer section 3b side, and a gas pressurizing and supplying device 6 is provided to the heat storage system.
Is not provided, the liquid refrigerant 2a in the liquid refrigerant 2a between the outer surface of the heat transfer section 3 on the heat transfer section 3a side and the solid refrigerant 2b.
Air bubbles circulate in a, and forced flow or turbulence occurs under the influence of the air bubbles. As a result, a heat transfer effect equivalent to forced convection occurs on the outer surface of the heat transfer section 3, and the heat transfer from the heat storage tank 1 per unit time occurs. The amount of heat recovery can be increased. On the other hand, the liquid storage medium 2a between the outer surface of the heat transfer section 3 on the heat transfer section 3b side and the solid storage medium 2b
In this case, natural convection is generated because bubbles do not flow, and natural convection heat transfer is dominant in heat transfer performance. Ka in equation (4)
And Kb are, based on the experimental result values of the first embodiment,
a = 4 · Kb, and FIG. 13 shows that the amount of heat recovered from the heat storage tank 1 per unit time is larger in FIG. 13 than in FIG.

As described above, if the internal melting type heat storage system shown in the fourth embodiment is used, a part of the heat transfer part does not flow through the refrigerant flow passage inside the heat transfer part during the cold storage operation. The heat transfer rate K [W / m ² K] representing the heat transfer performance of the heat transfer section during the melting operation by using a heat transfer section dedicated to melting in which a refrigerant having a temperature equal to or higher than the melting temperature of the refrigerant storage medium flows only during the melting operation. If the temperature difference ΔT [K] between the refrigerant and the refrigerant is the same, the effective heat transfer area during the melting operation can be increased in the same heat storage tank volume and the same cold storage amount. The amount of heat recovered from the tank can be increased. In addition, when air bubbles are blown out to the liquid storage medium between the outer surface of the heat transfer unit and the solid storage medium that also performs the cold storage operation, the heat transfer performance on the outer surface of the heat transfer unit improves, and the heat storage tank per unit time Increase the amount of heat recovered.

Embodiment 5 FIG. 14 is a diagram of a heat storage system according to the fifth embodiment. In the figure, 1 is a heat storage tank, 2 is a refrigerant storage medium, and 3a is a heat transfer section that circulates a refrigerant through an internal refrigerant circulation section in both the cold storage operation and the melting operation to generate and melt ice and 3b.
Is a heat transfer section dedicated to melting, which circulates the refrigerant to the internal refrigerant flow section only during the melting operation, 4 is a bubble blowing pipe, 5 is a bubble blowing hole,
Reference numeral 6 denotes a pressurized gas generation / supply device, 7 denotes a heat source unit, and 8 denotes a load unit, which correspond to those having the same reference numerals in the first embodiment.

The operation of the melting operation will be described with reference to FIG. When a refrigerant having a temperature higher than the melting temperature of the refrigerant body 2 flows through the refrigerant flow passage inside the heat transfer part 3a, the solid refrigerant body 2b present around the outer surface of the heat transfer part 3 is melted sequentially from the inside. At this time, the refrigerant flowing through the heat transfer unit 3 radiates heat using the latent heat of fusion of the refrigerant body 2. On the other hand, since the heat transfer section 3b is not used during the cool storage operation, the solid coolant 2b does not adhere to the surface of the heat transfer section 3b at the end of the cool storage operation, and the liquid coolant 2a exists around the heat transfer section 3b. When a refrigerant having a temperature higher than the melting temperature of the storage medium 2 flows through the refrigerant flow passage inside the heat transfer section 3a during the melting operation, heat exchange is performed with the storage medium 2, and heat is released using the sensible heat of the storage medium 2.

As shown in FIG. 14, the heat transfer section 3a has a bubble blowing hole 5 in the liquid refrigerant 2a between the outer surface of the heat transfer section 3a and the solid refrigerant 2b, and the blown air bubbles have a heat transfer section 3b side. By providing the bubble blowing holes 5 so as to circulate on the outer surface of the heat transfer unit 3b, the liquid refrigerant 2a in the liquid refrigerant storage unit 2a between the outer surface of the heat transfer unit 3 on the side of the heat transfer unit 3a and the solid refrigerant storage unit 2b is used. Bubbles circulate, and forced flow or turbulence occurs under the influence of the air bubbles. As a result, a heat transfer effect equivalent to forced convection occurs on the outer surface of the heat transfer unit 3, and the amount of heat recovered from the heat storage tank 1 per unit time Can be increased. On the other hand, bubbles also flow on the outer surface of the heat transfer section 3 on the side of the heat transfer section 3b, and the liquid refrigerant 2a around the outer surface of the heat transfer section 3b is disturbed, so that the heat transfer performance is higher than when natural convection heat transfer is dominant. Also increases.

12, 13, and 14, the total heat transfer coefficient K [W / m ² K] representing the heat transfer performance and the amount of heat recovery Q from the heat storage tank per unit time. The magnitude of [W] can be represented by the following inequality expression (10). K, Q in FIG. 12 <K, Q in FIG. 13 <14K, Q in FIG.

As described above, when the internal melting type heat storage system shown in the fifth embodiment is used, a part of the heat transfer part does not flow through the refrigerant flow passage inside the heat transfer part during the cold storage operation. The heat transfer rate K [W / m ² K] representing the heat transfer performance of the heat transfer section during the melting operation by using a heat transfer section dedicated to melting in which a refrigerant having a temperature equal to or higher than the melting temperature of the refrigerant storage medium flows only during the melting operation. If the temperature difference ΔT [K] between the refrigerant and the refrigerant is the same, the effective heat transfer area during the melting operation can be increased in the same heat storage tank volume and the same cold storage amount. The amount of heat recovered from the tank can be increased, and air bubbles are blown out to the liquid storage medium between the solid-state heat storage unit and the outer surface of the heat transfer unit on the side of the heat transfer unit that performs the cold storage operation. When air bubbles are passed, the heat transfer performance on the outer surface of the heat transfer section is improved, and Heat recovery from the heat storage tank per increases. The heat recovery amount is larger than in the case of the fourth embodiment.

Embodiment 6 FIG. FIG. 15 is a diagram of a heat storage system according to the sixth embodiment. Bubble blowing tube 4, bubble blowing hole 5, pressurized gas generation and supply device 6 described in Embodiments 1 to 5
Is replaced by a pressurized liquid blow-out pipe 4 ', a pressurized liquid blow-out hole 5', and a pressurized liquid generation and supply device 6 '. Other configurations are the same as those of the first to fifth embodiments.

The operation of the melting operation will be described with reference to FIG. A refrigerant having a temperature higher than the melting temperature of the refrigerant storage medium 2 is supplied from the load-side unit group 8 to the refrigerant flow passage inside the heat transfer section 3.
Alternatively, when flowing from the heat source unit 7, the solid refrigerant body 2b adhered and generated around the outer surface of the heat transfer section 3 is melted sequentially from the inside. At this time, the refrigerant flowing through the heat transfer section 3 is
The heat is dissipated into the storage medium 2 using the latent heat of fusion. The melting of the coolant 2 is caused by the solid coolant 2b attached to the heat transfer section 3.
Is melted from the innermost portion to become a liquid, and the liquid refrigerant 2a starts to exist between the outer surface of the heat transfer section 3 and the solid refrigerant 2b. When a pressurized gas is generated by the pressurized gas generator 6 ′ during the melting operation and the pressurized liquid is blown upward from below from the pressurized liquid blowout hole 5 ′ through the pressurized liquid blowout pipe 4 ′, heat transfer is performed. The liquid refrigerant body 2a near the upper surface of the portion 3 generates an upward flow. FIG. 16 is a schematic diagram of blowing the pressurized liquid upward.

When an upward flow occurs in the liquid storage medium 2a sandwiched between the outer surface of the heat transfer section 3 and the solid storage medium 2b, the heat transfer section 3
In the heat transfer on the outer surface, forced convection heat transfer becomes dominant from natural convection heat transfer, heat transfer performance is improved, and the amount of heat recovered from the heat storage tank 1 per unit time is increased.

When the pressurized liquid blow-out hole 5 ′ is close to the outer surface of the heat transfer section 3, the pressurized liquid is supplied to the liquid refrigerant storage body 2 a where the pressurized liquid between the outer surface of the heat transfer section 3 and the solid heat storage medium 2 b is desired to flow. Is increased and the pressurized liquid can be blown out efficiently, so that the heat transfer performance of the outer surface of the heat transfer section 3 is improved, and the amount of heat recovered from the heat storage tank 1 per unit time can be increased. it can.

When the pressurized liquid blow-out hole 5 ′ is uniformly installed in the entire lower part of the heat storage tank 1, the pressurized liquid that does not flow through the liquid refrigerant medium 2 a between the outer surface of the heat transfer unit 3 and the solid heat storage medium 2 b is removed. The amount of generated and circulated pressurized liquid is reduced, and the degree of improvement in the heat transfer performance of the outer surface of the heat transfer unit 3 is small. On the other hand, the pressurized liquid that does not flow through the liquid refrigerant 2a between the outer surface of the heat transfer unit 3 and the solid heat storage medium 2b flows through the outer surface of the solid refrigerant 2b,
A phenomenon occurs in which the solid storage medium 2b is melted wastefully and loses latent heat. In consideration of the heat transfer performance improvement efficiency, the liquid storage medium 2 between the outer surface of one heat transfer unit 3 and the solid heat storage medium 2b
a corresponding to one pressurized liquid blowing hole 5 ′
We want to ensure that the blown out pressurized liquid is sent to the liquid refrigerant 2a.

When the pressurized liquid blow-out pipe 4 'is once connected to the gas pressurized gas generating and supplying device 6' via the side surface of the heat storage tank 1 as shown in FIG. Therefore, since it is not necessary to make a hole in the heat storage tank 1 container, the heat storage tank 1 can be diverted to another use such as a dynamic ice heat storage heat storage tank. The upper cover of the heat storage tank 1 is not covered by welding but is covered with a lid so as to be detachable. As described above, the processing operation and the disassembly operation are simplified, and can be diverted to another use.

As described above, when the heat storage system shown in Embodiment 6 is used, a pressurized liquid blowing hole is provided in the liquid refrigerant between the outer surface of the heat transfer section and the solid refrigerant, and the pressure is increased during the melting operation. The pressurized liquid is generated by the liquid generating device, and the pressurized liquid is blown out from the pressurized liquid blowout hole through the pressurized liquid blowout pipe. Since the pressurized liquid flows upward while forcibly flowing and disturbing the liquid, the heat transfer performance of the outer surface of the heat transfer section is improved, and the amount of heat recovery from the heat storage tank per unit time can be increased. it can. Also, unlike air bubbles whose rising speed cannot be adjusted, by adjusting the amount of pressurization, the flow rate of the pressurized liquid blown out from the pressurized liquid outlet can be controlled, so that the flow rate control of the liquid refrigerant storage medium can be easily performed. Become. Further, since the irregular movement is less than that of the bubble, the pressurized liquid can be more reliably sent to the target position or area.

Embodiment 7 Bubble blowing tube 4, bubble blowing hole 5, pressurized gas generating and supplying device 6 and pressurized liquid blowing tube 4 ', pressurized liquid blowing hole 5', and pressurized liquid generating and supplying device 6 described in the first to sixth embodiments. FIG. 18 shows an installation example diagram of '. In the figure, 3 is a heat transfer section, 4 is a bubble blowing pipe, 5
Is a bubble blowing hole, 6 is a pressurized gas generating and supplying device, 4 'is a pressurized liquid discharging tube, 5' is a pressurized liquid discharging hole, 6 'is a pressurized liquid generating and supplying device, and 9 is a fixing device at the lower part of the heat transfer section. Reference numeral 10 denotes a heat transfer unit upper fixing device, which corresponds to the same reference numeral in the first embodiment.

The lower part 9 of the heat transfer part is made hollow so that gas or pressurized liquid can flow through it.
Also serves as a pressurized liquid blowing pipe 4 '. When a bubble blowout hole or a pressurized liquid blowout hole is installed at the fixing portion of the heat transfer portion lower fixing device 9, while the effects described in the first to sixth embodiments are obtained, the inside of the heat transfer portion stock fixing device and the bubble blowout tube are provided. 4. The cost of the heat storage tank can be reduced because it can also serve as the pressurized liquid blowing pipe 4 '.

As described above, when the internal fusion type heat storage system shown in the seventh embodiment is used, the inside of the fixing device at the lower part of the heat transfer section can be used as the bubble blowing pipe 4 and the pressurized liquid blowing pipe 4 ′. Since the number of components in the tank is reduced, the cost of the heat storage tank is reduced, and the number of obstacles in the tank is reduced, so that the heat loss corresponding to the heat capacity of the obstacles is reduced.

Embodiment 8 FIG. FIG. 19 shows a schematic diagram of a heat storage system according to the eighth embodiment. In the figure, 1 is a heat storage tank, 2
Is a refrigerant storage unit, 3 is a copper heat transfer unit, 4 is a bubble blowing tube, 5 is a bubble blowing hole, 6 is a pressurized gas generation and supply device, 7 is a heat source unit, 8 is a load unit, 11 is a PH detector, 12
Denotes a PH control device, and the same reference numerals as those in the first embodiment denote the same components.

FIG. 20 shows the relationship between the amount of dissolved oxygen in copper and water and the water PH. Dissolved oxygen is already saturated when tap water is put in the thermal storage tank, and it is difficult to control it. Even in the saturated state, if the pH is properly controlled, no copper ion is deposited. On the other hand, when the water PH becomes low and becomes acidic,
Copper ions may precipitate from the copper heat transfer section, causing a hole in the copper tube.

Then, the pH of the water in the heat storage tank is constantly detected, and if the pH becomes lower than 7, magnesium which is more easily ionized than copper ions is released from the PH controller into the heat storage tank, and the copper heat transfer medium is discharged. Prevent the phenomenon of copper ion precipitation from the part.

As described above, if the heat storage system described in the eighth embodiment is used, the PH in the heat storage tank is always detected,
When the pH is likely to turn acidic, the PH controller releases the metal that is easier to ionize than copper into the heat storage tank to prevent the copper ionization phenomenon from occurring in the copper heat transfer section, thereby extending the life of the copper heat transfer section. Can be kept long.

Embodiment 9 FIG. FIG. 21 shows a schematic diagram of a heat storage system according to the ninth embodiment. 1 is a heat storage tank, 2 is a refrigerant storage body,
3 is a heat transfer part, 4 is a bubble blowing tube, 5 is a bubble blowing hole, 6
Is a pressurized gas generation and supply device, 7 is a heat source unit, 8 is a load unit, 13 is a refrigerant liquid pump, and the same reference numerals and names as those in Embodiment 1 including the others have the same reference numerals and names. I have.

Since the refrigerant liquid pump 13 has little compression work, it consumes less power than a compressor or a gas pump.

An operation example in which the refrigerant liquid pump 13 is used to circulate the refrigerant using Freon R22 as the refrigerant will be described. First,
The peak cut operation in which the cooling load of the group of load-side units 8 is covered only by the latent heat of the solid-state storage medium 2b in the heat storage tank 1 will be described. The refrigerant flowing out of the refrigerant liquid pump 13 is at 7 ° C.
It flows into the load-side unit group in a liquid state, where it absorbs heat and is gasified by an evaporating action. The gasified refrigerant flows into the heat storage tank heat transfer unit 3 via a valve on the load side on the liquid pipe and an expansion device that does not perform expansion. At this time, the pressure loss from the load side unit to the inlet of the heat storage tank heat transfer section 3 was 0.05
If there is MPa, the refrigerant temperature at the inlet of the heat storage tank heat transfer section 3 becomes about 5 ° C. The refrigerant radiates heat in the heat storage tank heat transfer unit 3 and is liquefied by the condensation action, and then flows into the inlet of the refrigerant liquid pump 13.

In the melting operation in the conventional ice heat storage system, the refrigerant flowing into the heat storage tank heat transfer section 3 was in a high-pressure gas state compressed by a compressor or a gas pump. When it circulates using the refrigerant liquid pump 13, the temperature becomes almost the same as the evaporation temperature of the load side unit group 8. Assuming that the effective outside area A [m ² ] of the heat transfer section 3 in the heat storage tank 1 and the heat transfer rate K [W / m ² K] representing the heat transfer performance of the heat transfer section 3 are constant, Equation (1)
The amount of heat recovered from the heat storage tank 1 is determined by the temperature difference between the refrigerant flowing inside the heat transfer section 3 and the refrigerant storage medium 2. Q = A · K · ΔT Equation (1)

For example, the temperature of the refrigerant at the inlet of the heat storage tank heat transfer section 3 is conventionally 20 ° C., and when the refrigerant liquid pump 13 is used, it is 5 ° C.
Assuming that the temperature of the refrigerant storage medium 2 is 0 ° C., the recovered heat ratio is Q Conventional: Q refrigerant liquid pump = AK · (20 ° C.-0 ° C.): AK · (5 ° C.-0 ° C.) = 4 : Equation (11), and if the conventional melting method is used as it is, the amount of heat recovered from the heat storage tank 1 per unit time is reduced to ４.

Therefore, the outer surface of the heat transfer section 3 and the solid refrigerant
By blowing air bubbles into the liquid storage medium 2a during the heat transfer and improving the heat transfer performance, even if the temperature difference between the refrigerant circulating inside the heat transfer unit 3 and the storage medium 2 becomes smaller than in the conventional system, it is the same as before. Of heat recovery. According to the experimental results of Embodiment 1, the average heat transmittance at the time of blowing bubbles = 566 [W / m ² K] The average heat transmittance at the time of no blowing bubbles = 140 [W / m]
² K], so if the heat transfer section 3 has the same heat transfer area A [m ² ], Q conventional = A · 140 · (20 ° C-0 ° C) = 2800 · A [W] · Q refrigerant liquid pump = A · 566 · (5 ° C.−0 ° C.) = 2830 · A [W], and even if a refrigerant liquid pump is provided in the internal melting type heat storage system by blowing bubbles, the same amount of heat recovery as that of a heavier can be obtained.

As described above, if the heat storage system shown in the ninth embodiment is used, if bubbles are blown out to the liquid refrigerant 2a between the outer surface of the heat transfer section 3 and the solid refrigerant 2b during the melting operation, the refrigerant Even if the refrigerant is circulated by the pump, the same amount of heat recovered from the heat storage tank as that of the related art can be obtained.

Embodiment 10 FIG. FIG. 21 shows Embodiment 10
1 shows a schematic diagram of a heat storage system. The system configuration is the same as that of the ninth embodiment, and a description thereof will be omitted. FIG. 22 shows an example of the cooling operation load per day when the peak shift and peak cut operations are performed. Next, the bubble blowing or liquid blowing timing in the melting operation will be described.

The main purpose of providing heat storage by providing a heat storage tank is to level the power consumption during the day and night. Power is converted to cold energy using nighttime power and stored, and daytime power consumption is reduced by using the cold energy stored during the day. In the method of using the cold energy stored in the heat storage tank, the operation in which the cooling load of the load side unit group is entirely covered by only the cold energy in the heat storage tank without operating the heat source unit is called peak cut operation, and the compression in the heat source side unit is performed. The operation covered in parallel with the cooling operation by the heat pump or the gas pump is called a peak shift operation. In alleviating the tightness of power supply due to the recent surge in power demand,
The peak cut operation performed during the daytime, especially during a time when the power demand is large, has a great effect.

The heat storage operation is performed from 20:00 at night to 6:00 in the early morning. The flow of the refrigerant in this case will be described with reference to FIG. The valve on the load side unit side in the middle of the liquid pipe is closed, the valve on the heat source side unit is open, and the expansion device in the middle of the pipe through the liquid pipe and the heat storage tank 1 has an opening degree. . The high-pressure gas refrigerant compressed by compression means such as a compressor and a gas pump provided in the heat source unit 7 also flows through a heat exchanger provided in the heat source unit 7 to convert the refrigerant into a high-pressure liquid state by a condensation action. After that, the liquid enters a low-pressure two-phase state through a valve from the heat source side unit on the liquid pipe and an expansion device in front of the heat storage tank, and flows to the heat transfer unit 3 in the heat storage tank. In the heat transfer unit 3, the refrigerant becomes a low-pressure gas state by the evaporating action, and returns to the suction side of the compressor or the gas pump provided in the heat source unit 7. In the heat storage tank 1, the temperature of the liquid refrigerant decreases due to the evaporating effect of the refrigerant, and a solid refrigerant appears by solidification.

At this time, when there is a cooling load in the load side unit 8, a part of the refrigerant is circulated to the load side unit 8. The ratio of the amount of the refrigerant circulated to the heat transfer section 3 of the heat storage tank 1 to the amount of the refrigerant circulated to the load-side unit 8 is determined by the expansion device in front of the heat storage tank 1 and the liquid line provided in the load-side unit 8. Is uniquely determined by the degree of opening of the expansion device.

Next, from 8:00 in the morning to 13:00 in the afternoon, and 1 in the evening
Peak shift cooling operation is performed from 6:00 to 18:00 in the evening. The flow in this case will be described with reference to FIG. The valve on the load side unit side in the middle of the liquid pipe is open, the valve on the heat source side unit is open, and the expansion device located in the middle of the pipe between the liquid pipe and the heat storage tank 1 does not perform the expansion action. Part of the high-pressure gas refrigerant compressed by compression means such as a compressor or a gas pump provided in the heat source unit 7 flows to the heat transfer unit 3 in the heat storage tank 1. In the heat transfer section 3, the refrigerant becomes a medium-pressure liquid state due to the condensation action, and flows into the refrigerant junction via the expansion device.

On the other hand, the remainder of the high-pressure gas refrigerant compressed by the compressor or the gas pump flows through the heat exchanger provided in the heat source unit 7 and the refrigerant is turned into a high-pressure liquid state by the condensation action. The pressure is reduced a little by the expansion device provided in 7 and flows into the junction. The medium-pressure liquid refrigerant that has joined at the junction flows into the load-side unit 8, flows out in a low-pressure gas state by expansion and evaporation, and returns to the suction port of the compressor or gas pump of the heat-source-side unit 7. .
At this time, in the heat storage tank 1, the heat release of the refrigerant causes the solid refrigerant storage medium to melt, and the temperature of the liquid refrigerant storage medium to rise.

Next, a peak cut cooling operation is performed from 13:00 in the day to 16:00 in the evening. The flow of the refrigerant in this case is shown in FIG.
1 will be described. The valve on the load side unit side in the middle of the liquid pipe is open, the valve on the heat source side unit is closed, and the expansion device in the middle of the pipe through the liquid pipe and the heat storage tank 1 does not perform an expansion action. The liquid refrigerant on the discharge side of the liquid pump 13 flows into the load side unit group 8. At this time, the expansion device of the operating load side unit group 8 is set to a state in which the expansion operation is not performed. In the operation load side unit group 8, the refrigerant becomes a gas state by the evaporating action, and flows into the heat transfer unit 3 of the heat storage tank 1. In the heat transfer section 3, the refrigerant is in a liquid state by the condensation action and returns to the liquid pump 13 suction port.

In the peak cut operation, a device having a large compression action such as a compressor and a gas pump on the heat source side is not operated, and the liquid pump 13 having a small compression action for performing only the compression action for sending out the liquid refrigerant is operated. Therefore, the power consumption of the peak cut operation is smaller than that of the peak shift operation.

Bubble blowing and liquid blowing are performed during the peak cut operation. In this case, the solid storage medium is melted by the peak shift operation from 8:00 to 13:00 in the morning, and between the surface of the heat transfer unit 3 and the solid storage medium at 13:00 of the start of the peak shift operation. Is sufficiently present in the liquid storage medium, and the effect of improving the heat transfer performance by blowing bubbles or blowing liquid into the liquid storage medium can be reliably obtained.

Further, since the liquid pump 13 has a small compression action, there is almost no pressure difference between the discharge side and the suction side. Therefore, the temperature of the refrigerant flowing into the heat transfer section 3 of the heat storage tank 1 is also low, and the temperature difference between the refrigerant and the heat storage medium in the heat storage tank 1 cannot be obtained, so that the refrigerant discharged from the compressor or the gas pump causes the heat storage tank 1 to condense. The amount of heat recovery is smaller than that of. Bubble blowing and liquid blowing are performed to compensate for this.

A specific example will be described below. The refrigerant is R22. [A] When discharged from a compression means such as a compressor or a gas pump: refrigerant is 1.1 [MPa] (saturation temperature T _ca = 26 ° C.) [B] When discharged from a liquid pump: refrigerant 0.61 [ MP
a] (saturation temperature T _cb = 6 ° C.). Further, water (ice) is used as the refrigerant storage medium, and the temperature _Tw = 0.
° C. In this case, the amount of heat Q [W] that can be recovered in the heat storage tank is shown below. [A] Q = A · K _a · (T _ca −T _w ) = 26 A · K _a [B] Q = A · K _b · (T _cb −T _w ) = 6 A · K _b A: Heat transfer area [m ² ] K: Heat transmission rate [W / m ² K]

[0102] If If K _a = K _b, the compressor and the gas pump when using a liquid pump as compared to when using heat recovery amount 6/26
= 23%, which is about 1/4. Therefore, when the liquid pump 13 is used, air bubbles having the effect of quadrupling the heat transfer rate or liquid blowing having the effect of improving the heat transfer rate are performed to recover the same heat as when the compressor or gas pump is used. Hold the volume.

As described above, according to the present embodiment, by performing the gas blowing and the liquid blowing during the peak cut operation, it is possible to perform the operation providing the same cooling load as that during the peak shift operation.

Embodiment 11 FIG. FIG. 23 shows an eleventh embodiment.
FIG. 3 is a perspective view showing a heat transfer tube and its peripheral structure in the heat storage system of FIG. In FIG. 23, 3 is a heat transfer tube, 20 is a cylinder fixed to the heat transfer tube 3 and covered with a heat transfer tube surface at a predetermined interval, made of a heat conductive material, and radially expanded downward. It has a shape. Other configurations are the same as those of the first embodiment, and a description thereof will be omitted.

The operation of the melting operation is the same as that of the first embodiment described with reference to FIG. In the first embodiment, the bubble passage is a liquid refrigerant formed by the outer surface of the heat transfer tube 3 and the solid refrigerant, but in the present embodiment, the space between the heat transfer tube 3 and the cover 20 is a bubble passage. I have. With such a configuration, melting of the solid-state storage medium progresses, the gap between the heat transfer tube 3 and the solid-state storage medium may be widened, or the solid-state storage medium may be partially melted to form a hole. Even so, the bubble rises on the surface of the heat transfer tube 3 by the cover 20, and the flow of the liquid storage medium near the outer surface of the heat transfer tube 3 is maintained.

Further, since the lower part of the cover 20 is radially expanded, the irregularly moving air bubbles are reduced by one.
0, and can be reliably captured in the upper cover 20 even in a direction slightly away from the heat transfer tube 3. Furthermore, if the cover 20 is made of a heat conductive material and fixed to the heat transfer tube 3, the cover 20 also plays a role as a fin, and heat exchange between the refrigerant storage body 2 and the refrigerant in the heat transfer tube is promoted. .

[0107]

As described above, according to the present invention, heat is exchanged between the heat storage tank filled with the refrigerant storage medium and the refrigerant installed in the heat storage tank and the refrigerant storage medium in the heat storage tank. A heat transfer unit, a bubble blowing unit provided in the lower part of the heat storage tank and having a gas blowing hole, a pressurized gas generation / supply unit for supplying a pressurized gas to the bubble blowing unit, and a connection to the heat transfer unit Since the heat source unit and the load-side unit are provided, and the bubble blowing unit is installed so as to supply air bubbles into the liquid refrigerant between the outer surface of the heat transfer unit and the solid refrigerant storage unit covering the heat transfer unit. Bubbles flow upward along the outer surface of the heat transfer unit in the liquid storage medium and generate forced flow or turbulence in the surrounding liquid storage medium, so that the heat transfer performance of the outer surface of the heat transfer unit is improved, The effect of promoting heat recovery from the tank is obtained.

Further, since the heat transfer portion is a heat transfer fin, the effect of increasing the area of contact with the liquid storage medium generated by the irregularly moving air bubbles can be obtained, so that heat can be reliably recovered.

Further, the heat transfer fin is a plate-like fin,
Multiple bubble outlets correspond to one plate fin surface, so even if one of the bubble outlets is clogged, the heat exchange efficiency of the plate fins is maintained by the bubbles blown out from the other bubble outlets can do.

Further, since the pressurized gas generation / supply unit controls the amount of air bubbles blown into the liquid storage medium, the effect of adjusting the amount of heat recovered from the heat storage tank is obtained.

Further, since the heat transfer unit and the load side unit are connected to the heat transfer unit via the refrigerant pipe, the internal melting type heat storage system is provided. The effect that the exchange efficiency can be improved is obtained.

Further, since the refrigerant is not circulated through the internal refrigerant flow passage during the cold storage operation, the heat transfer section dedicated to melting is provided only for the melting operation, so that the refrigerant having a temperature equal to or higher than the melting temperature of the refrigerant body is provided.
With the same heat storage tank volume and the same cold storage amount, an effective melting heat transfer area during the melting operation can be increased, and the effect of increasing the amount of heat recovered from the heat storage tank per unit time can be obtained.

Further, since the bubble blowing section is provided so as to supply bubbles into the liquid refrigerant storage medium between the outer surface of the heat transfer section dedicated for melting and the solid refrigerant storage section covering the heat transfer section dedicated for melting, the melt transfer section is provided. The effect of improving the heat transfer performance of the outer surface of the heat part and realizing an increase in the amount of heat recovery from the heat storage tank per unit time is obtained.

Further, since the gas blowing holes are arranged below the outer surface of the heat transfer section, when bubbles are blown out from the bubble blowing holes through the bubble blowing pipe, the bubbles rise in the liquid refrigerant due to buoyancy. Since the air bubbles flow along the outer surface of the heat transfer section from the lower end to the upper end in the vertical direction of the outer surface of the heat transfer surface while generating forced flow or turbulence in the surrounding liquid, the heat transfer surface improves heat transfer performance. And the effect of realizing an increase in the amount of heat recovery from the heat storage tank per unit time is obtained.

Further, since the gas outlet and the lower portion of the outer surface of the heat transfer section are brought into contact with or close to each other, a pressurized gas is generated by the pressurized gas generator during the melting operation, and the bubble outlet is provided through the bubble outlet pipe. When air bubbles are blown out of the liquid storage medium due to buoyancy, the air bubbles rise with irregular and minute vibrations. Because the probability of air bubbles flowing in the medium increases, as a result of improving the air bubble distribution efficiency,
The heat transfer performance of the outer surface of the heat transfer section is improved, and an effect of increasing the amount of heat recovered from the heat storage tank per unit time is obtained.

Further, since the heat transfer section is a cylindrical tube and the gas blow-out hole is provided directly below or near the heat transfer tube, a pressurized gas is generated by the pressurized gas generator during the melting operation, and the bubble is blown out. When bubbles are blown out from the bubble blowing holes through the tube, the bubbles rise in the liquid refrigerant body with irregular and minute vibrations due to buoyancy, so if the bubble blowing holes are directly below the heat transfer portion, for example, Even if there is a distance between the heat transfer section and the bubble blowing hole, the probability that the bubbles flow through the liquid refrigerant as a path through which the bubbles are to flow is increased.As a result, the bubble flow efficiency is improved. The effect of improving the heat transfer performance and realizing an increase in the amount of heat recovery from the heat storage tank per unit time is obtained.

Further, since the pressurized liquid blowout section having the pressurized liquid blowout hole formed in place of the bubble blowout section is provided with the pressurized liquid generation and supply apparatus instead of the pressurized gas generation and supply apparatus, the melted operation is performed during the melting operation. When the pressurized liquid is generated by the pressurized liquid generation device and the pressurized liquid is blown upward from the pressurized liquid blowout hole through the pressurized liquid blowout pipe, the liquid refrigerant accumulates along the outer surface of the heat transfer unit. Since the upward flow is generated, the heat transfer performance of the outer surface of the heat transfer section is improved, and an effect of realizing an increase in the amount of heat recovery from the heat storage tank per unit time is obtained.

[0118] Further, since an instrument for fixing the lower part of the heat transfer section in the heat storage tank is provided, and the instrument is the bubble blowing section or the pressurized liquid blowing section, the apparatus for fixing the lower portion of the heat transfer section can be connected to the air bubble or heat storage section. The effect can also be obtained as the pressure liquid blowing pipe can be used, and the cost of the heat storage system can be reduced.

Further, since a liquid pump for circulating a refrigerant is provided between the heat transfer section in the heat storage tank and the load side unit,
Since the heat transfer performance can be improved by forcible flow or turbulence in the liquid storage medium on the outer surface of the heat transfer unit, compared to conventional gas pumps and compressors, when using a refrigerant liquid pump, the heat storage tank heat transfer unit Even if the temperature of the refrigerant flowing into the refrigerant becomes low, it is possible to obtain a good amount of heat recovered from the heat storage tank per unit time, and the refrigerant liquid pump can reduce the amount of power consumption because of the small compression process. The effect that the running cost of the system can be reduced can be obtained.

Further, the pH of the liquid storage medium in the heat storage tank
A pH detecting unit for detecting the value of the liquid, and a PH control unit for controlling the PH value of the liquid storage medium according to the detection result of the PH detecting unit, so that the heat transfer unit material in the heat storage tank is ionized. Thus, the effect of preventing the heat transfer section from deteriorating can be obtained.

Further, a solid-state refrigerant is generated in the heat storage tank in a first predetermined time zone, and the solid cold storage medium in the heat storage tank is generated in a second predetermined time zone that is not continuous with the first predetermined time zone. With a peak cut means to melt the medium and recover heat,
Bubble blowing or liquid blowing can be performed smoothly during the peak cut operation, and the effect of efficiently recovering heat can be obtained.

Further, since air bubbles are passed through the liquid refrigerant between the surface of the heat transfer part and the solid refrigerant to promote the flow of the liquid refrigerant, the liquid refrigerant present on the surface of the heat transfer part is forced to move. The flow and turbulence are generated to improve the heat transfer performance of the outer surface of the heat transfer unit, and an effect of increasing the amount of heat recovery from the heat storage tank per unit time is obtained.

Further, since the amount of melting is adjusted by controlling the amount of bubbles blown into the liquid storage medium, the effect of adjusting the amount of heat recovered from the heat storage tank can be obtained.

Further, since the pressurized liquid is passed instead of the air bubbles, an upward flow is generated in the liquid storage medium present on the surface of the heat transfer section, so that the heat transfer performance on the outer surface of the heat transfer section is improved, and heat recovery is performed. The effect that the quantity can be increased can be obtained.

Further, since bubbles or pressurized liquid are passed during the peak cut operation that is not continuous with the generation of the solid refrigerant, the bubble or liquid can be blown out smoothly at the start of the peak cut operation, and the heat recovery can be efficiently performed. The effect that can be achieved is obtained.

A heat storage tank filled with a refrigerant storage medium, a heat transfer unit installed in the heat storage tank for exchanging heat between the refrigerant and the refrigerant storage medium in the heat storage tank, and a heat transfer unit installed in the lower part of the heat storage tank A bubble blowing section having a gas blowing hole formed therein, a pressurized gas generating / supplying section supplying a pressurized gas to the bubble blowing section, and a heat source unit and a load side unit connected to the heat transfer section, A cover is formed on the outer surface of the heat transfer section, and the bubble blowing section is provided so as to supply bubbles into the liquid storage medium between the heat transfer section and the cover. Air bubbles circulate upward along with the water and generate forced flow and turbulence in the surrounding liquid, improving the heat transfer performance of the outer surface of the heat transfer section and increasing the amount of heat recovered from the heat storage tank per unit time Is obtained.

Further, since the cover is formed of a solid storage refrigerant, air bubbles can be circulated in the liquid refrigerant storage medium along the outer surface of the heat transfer section with a simple structure and with forced flow or turbulence in the surrounding liquid. The effect that can be performed is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram of a heat storage system according to Embodiment 1 of the present invention.

FIG. 2 is a diagram of a heat storage tank according to the first embodiment.

FIG. 3 is a schematic diagram of bubble blowing according to the first embodiment.

FIG. 4 is another schematic diagram of bubble blowing according to the first embodiment.

FIG. 5 is an example of installation of a bubble blowing pipe according to the first embodiment in a heat storage tank.

FIG. 6 is an experimental result diagram of the heat transfer coefficient outside the heat transfer section according to the first embodiment.

FIG. 7 is a diagram of a heat storage system according to a second embodiment.

FIG. 8 is a diagram of a heat storage tank according to the second embodiment.

FIG. 9 is a schematic diagram of bubble blowing according to the second embodiment.

FIG. 10 is a diagram of a heat storage tank according to the third embodiment.

FIG. 11 is a schematic diagram of bubble blowing according to the third embodiment.

FIG. 12 is a diagram of a heat storage tank according to the fourth embodiment.

FIG. 13 is another heat storage tank diagram of the fourth embodiment.

FIG. 14 is a diagram of a heat storage tank according to the fifth embodiment.

FIG. 15 is a diagram of a heat storage system according to a sixth embodiment.

FIG. 16 is a schematic diagram of a pressurized liquid upward according to a sixth embodiment.

FIG. 17 is an installation example of a pressurized liquid blowing pipe according to the sixth embodiment in a heat storage tank.

FIG. 18 is a diagram illustrating an example of installation of a lower part of a heat transfer part and a heat transfer part lower fixing device according to the seventh embodiment.

FIG. 19 is a diagram of a heat storage system according to an eighth embodiment.

FIG. 20 is a diagram illustrating a relationship among copper, water PH, and dissolved oxygen amount in water according to the eighth embodiment.

FIG. 21 is a diagram of a heat storage system according to the ninth and tenth embodiments.

FIG. 22 is an example of a daily cooling operation load according to the tenth embodiment.

FIG. 23 is a view around a heat transfer tube of the heat storage system of the eleventh embodiment.

FIG. 24 is a diagram of a heat storage system shown as a conventional example.

FIG. 25 is a diagram of a heat storage system shown as another conventional example.

[Explanation of symbols]

Reference Signs List 1 heat storage tank, 2 refrigerant storage medium, 3 heat transfer section, 4 bubble blowing pipe, 4 'pressurized liquid blowing pipe, 5 bubble blowing hole, 5' pressurized liquid blowing hole, 6 pressurized gas generation and supply device, 6 ' Pressure liquid generation and supply device, 7 heat source unit, 8 load side unit group, 9 heat transfer unit lower fixing device, 10 heat transfer unit upper fixing device, 11 PH detection device, 12 PH control device, 13 refrigerant liquid pump,
20 covers.

Claims (21)

[Claims] 1. A heat storage tank filled with a refrigerant storage medium, a heat transfer unit installed in the heat storage tank and exchanging heat between a refrigerant and the refrigerant storage medium in the heat storage tank, and installed in a lower part of the heat storage tank A bubble blowing section having a gas blowing hole formed therein, a pressurized gas generating / supplying section supplying a pressurized gas to the bubble blowing section, and a heat source unit and a load side unit connected to the heat transfer section, A heat storage system, wherein the bubble blowing unit is provided so as to supply air bubbles into a liquid storage medium between the outer surface of the heat transfer unit and the solid storage medium covering the heat transfer unit. 2. The heat storage system according to claim 1, wherein said heat transfer section is a heat transfer fin. 3. The heat storage system according to claim 2, wherein the heat transfer fins are plate-like fins, and one plate-like fin is provided with a plurality of bubble blowing holes on one surface. 4. The heat storage system according to claim 1, wherein the pressurized gas generation / supply unit controls an amount of bubbles blown into the liquid storage medium. 5. The heat storage system according to claim 1, wherein the heat storage unit is an internal fusion type heat storage system including a heat source unit and a load unit connected to the heat transfer unit via a refrigerant pipe. 6. A heat transfer unit for exclusive use of melting, wherein the refrigerant does not flow through the internal refrigerant flow passage during the cold storage operation and the refrigerant having a temperature equal to or higher than the melting temperature of the refrigerant storage medium flows only during the melting operation. 5. The heat storage system according to 5. 7. The air bubble blowing section is provided so as to supply air bubbles into a liquid refrigerant storage medium between the outer surface of the heat transfer section exclusively for melting and the solid refrigerant storage section covering the heat transfer section exclusively for melting. The heat storage system according to claim 6. 8. The thermal storage system according to claim 1, wherein the gas outlet is disposed below an outer surface of the heat transfer section. 9. The heat storage system according to claim 1, wherein the gas outlet and the lower portion of the outer surface of the heat transfer section are in contact with or close to each other. 10. The heat storage system according to claim 1, wherein the heat transfer section is a cylindrical tube, and the gas outlet is provided immediately below or near the heat transfer tube. 11. A pressurized liquid blowout unit having a pressurized liquid blowout hole formed therein in place of the bubble blowout unit, and a pressurized liquid generation and supply device is provided in place of the pressurized gas generation and supply device. The heat storage system according to any one of claims 1 to 10. 12. An apparatus for fixing a lower portion of the heat transfer section in the heat storage tank, wherein the apparatus is the bubble blowing section or the pressurized liquid blowing section.
The heat storage system according to any one of the first to third aspects. 13. The heat storage system according to claim 1, further comprising a liquid pump that circulates a refrigerant between the heat transfer unit in the heat storage tank and the load-side unit. . 14. A fuel cell system comprising: a PH detector for detecting a PH value of a liquid refrigerant in the heat storage tank; and a PH controller for controlling a PH value of the liquid refrigerant in accordance with a detection result of the PH detector. The heat storage system according to claim 1, wherein: 15. A solid-state storage medium is generated in the heat storage tank during a first predetermined time zone, and the solid cold storage in the heat storage tank is generated during a second predetermined time zone that is not continuous with the first predetermined time zone. 2. The apparatus according to claim 1, further comprising a peak cut unit that covers the cooling load on the load side only with the cooling heat that is obtained by melting and recovering the medium.
15. The heat storage system according to any one of claims 14 to 14. 16. A method for improving the heat transfer performance of a surface of a heat transfer section by promoting the flow of the liquid storage medium by causing bubbles to pass through the liquid storage medium between the surface of the heat transfer section and the solid storage medium. A method for melting a heat storage system. 17. The melting method for a heat storage system according to claim 16, wherein the amount of melting is adjusted by controlling the amount of bubbles blown into the liquid storage medium. 18. The method for melting a heat storage system according to claim 16, wherein a pressurized liquid is passed instead of bubbles. 19. The melting method for a heat storage system according to claim 16, wherein the passage of bubbles or pressurized liquid is performed during a peak cut operation that is not continuous with the generation of the solid refrigerant. 20. A heat storage tank filled with a refrigerant storage medium, a heat transfer unit installed in the heat storage tank and exchanging heat between the refrigerant and the refrigerant storage body in the heat storage tank, and installed in a lower part of the heat storage tank. A bubble blowing section having a gas blowing hole formed therein, a pressurized gas generating / supplying section supplying a pressurized gas to the bubble blowing section, and a heat source unit and a load side unit connected to the heat transfer section, A heat storage system, wherein a cover is formed on an outer surface of the heat transfer unit, and the bubble blowing unit is provided so as to supply bubbles into a liquid storage medium between the heat transfer unit and the cover. 21. The heat storage system according to claim 20, wherein said cover is formed of a solid storage refrigerant.