SI22504A - Pressureless seasonal water-based thermal tank with system for emphasising water temperature layers - Google Patents

Abstract

The pressureless seasonal water-based thermal tank enables an indirect improvement of the efficiency rate of gathering solar energy, its transformation into heat, while in particularly the direct improvement of the efficiency rate of the seasonal heat storage. The application according to the described invention includes full (4) or half linear lamella structures (5), which are located above the filling heat exchangers (1) or beneath the drain heat exchangers (2) enabling focused and limited Reyleigh-Bernard convection (10). This prevents horizontal mixing of water (6) and the guaranteed inducing of a maximum thermally-layered water in the storage tank, which provides a 30 % enhanced efficiency rate in gathering and releasing heat from the storage tank compared to any existing systems. There is an additional description of the storage tank with a bendable water- nonpermeable foil (16), which in a simple way solves the problem of water expansion due to temperature changes (17) and thus pressure equalisation.

Description

NON-CURRENT SEASONAL WATER HEAT TANK WITH SYSTEM FOR STRESSING WATER TEMPERATURE

Subject of the invention:

The subject of the invention is a non-pressurized seasonal heat storage tank in which heat is stored by utilizing the heat capacity of water. The seasonal heat storage tank described is designed to store heat from the solar system in the warmer part of the year until the cooler part of the year. The essence of the invention is a new configuration of the seasonal reservoir, where the system for emphasizing the temperature layering of water achieves up to 30% better efficiency of supply and extraction of heat from the reservoir compared to any existing systems. In addition, the invention describes the construction of a tank with a flexible watertight foil, which can easily solve the problem of water elongation during temperature changes and thereby compensate for pressure.

Problem definition:

A technical problem solved by the invention is the indirect increase in the efficiency of solar energy converted to heat and the direct increase of the efficiency of storage and consumption of heat intended for heating buildings and sanitary water. Thus, the invention can effectively contribute to the use of solar energy for the purposes described.

Physical background of the problem:

The utilization of heat supply to the storage tank or the removal of heat from the storage tank depends on the temperature gradient at the site of heat transfer and the ability to accelerate heat flows within the storage tank. At the point of delivery or. Therefore, it is necessary to ensure the lowest temperatures of the storage tank and to transfer the heat as efficiently as possible to the place where energy is extracted from the storage tank, where the highest possible temperatures are desired. The latter can only be efficiently solved in a liquid reservoir by taking advantage of the phenomenon of hot liquid buoyancy in the cold. That is why heat supplies are always there

Form SIPO P-1 below and drains above.

However, it comes because of the nonlinear phenomena of t.i. Rayleigh-Bernard convection to strong mixing even at relatively short vertical transmissions (at distances greater than 10 cm). Therefore, Rayleigh-Bernard convection should be appropriately curtailed to prevent horizontal mixing in vertical heat transfer and to provide the highest possible temperature layering under realistic operating conditions of the seasonal heat storage tank. Additionally, the efficiency of the reservoir may be reduced due to heat losses resulting from different uses of expansion systems.

Known solutions:

Some variants of the seasonal reservoir are known, where heat is stored in the heat capacity of water. The simplest and most primitive solution is the solution without heat exchangers, where the heated medium from the primary system, which captures solar energy and converts it into heat, directly enters the reservoir. Due to the fluid flow, the inlet warm medium is mixed at practically 0.5 m above the inlet point with the cool medium of the reservoir, which does not allow the stimulation of temperature layering. Such solutions can therefore only be used in small storage tanks, which serve to mitigate the shocks of consumption. Such solutions cannot be scaled and are therefore unsuitable for use in seasonal storage tanks, since the efficiency of filling and discharging would be too low. In addition, in this case, the medium in the storage tank must be the same as the transmission medium in the (solar) energy capture system, which means the use of a large amount of expensive transmission medium with a freezing point below 40 “C.

Another solution involves the use of heat exchangers. In the absence of direct mass flows, the storage medium may be different from the medium of the energy capture system. However, the problem of horizontal mixing due to the appearance of Rayleigh-Bernard convection remains. Such reservoirs have the same problems as previously mentioned when scaling to altitudes greater than 0.5m and are not suitable for use as seasonal storage tanks.

Another solution is to use heat exchangers together with a system for emphasizing layering on the basis of non-return valves, which in the long run is problematic due to the mechanical operation of submerged valves.

Recent solutions include the use of layering systems based on vertical tube-based structures (Pat. JP2279937, Pat. DE10121842) or open cylindrical symmetry funnels without heat exchanger (Pat. EP0861985). The first problem is a large amount of removable media, which is the same as the medium in the storage,

The SIPO P-1 form and the flow mass (not the one excited by Rayleigh-Bernard convection), which inevitably breaks down the temperature stratification and is not suitable for seasonal storage tanks. Even if the system were used in conjunction with heat exchangers, the cylindrical symmetry of the solutions implemented is not effective at larger storage tanks, since they are inevitable. 'Dead zones' of the reservoir to which heat cannot be supplied or fed on ten-minute time scales typical of the actual operating conditions of the seasonal reservoir. Thus, the efficiency of such a storage tank is up to 50% less. In addition, in the case of open structures with cylindrical symmetry, structure leakage occurs, since all vertical flow is directed to a narrow vertical-open core. This again reduces the efficiency of the tank.

With all known solutions, the issue of improving seasonal storage efficiency remains unresolved.

Description of solutions to the problem of the invention:

According to the invention, the problem is solved by a linear lamellar RayleighBernard convection limiting system in combination with heat exchangers in a reservoir attached to a freestanding support structure, as explained below and shown in the following figures:

Figure 1 - view of a typical seasonal tank structure in the case of dual charge heat exchanger (1), single heat exchanger for heating supply and dual heat exchanger for hot water (2) with accompanying lamella structures (4) and (5) for limiting Rayleigh- Bernard convection

Figure 2 - Schematic illustration of the expansion of a core of warm rising current above a heat exchanger tube at unrestricted Rayleigh-Bernard convection (6)

Figure 3 - Side view of the lamellar structure of a RayleighBernard convection limiting system (4)

Figure 4 is a cross-sectional view of the lamellar structure of a RayleighBernard convection limiting system (4) with a marked lamella width (7), an inclination (8) and a distance (9) and a schematic representation of the Rayleigh-Bernard convection current in the case of heavy buoyancy (10) and in when buoyancy becomes negligible (11)

OhrAZPC SIPO P-1

Figure 5 - cross-section of the half-lamellar structure of a system (5) for limiting Rayleigh-Bernard convection for implementation along the tank wall

Figure 6 - Vertical projection of the foil lampholder anchorages on the tension cords to achieve a uniform tension

Figure 7 - Design of a non-pressurized design of a flexible foil tank using wrinkles

The described tank contains charge heat exchangers (1) that supply heat to the tank. In order to prevent the hot rising current, to the occurrence of t.i. Rayleigh-Bernard convections and t.i. Rayleigh-Bernard instability zones (6), which promote pronounced horizontal mixing of warm flow with cold surrounding medium, according to the invention, a lamellar structure (4) is provided above the filling exchanger containing two mirror-symmetrical vertical series of inclined parallel lamellae (3). warm flow of Rayleigh-Bernard convection (10).

Analogously, each emptying heat exchanger (2) removes heat from the reservoir by taking heat from the surrounding medium and therefore cooling it. The descending cooled medium is limited by the installation of a lamellar structure that differs from the filling only in that it focuses the cold downstream.

According to the invention, said lamellar structures are assembled according to the following rules:

1. The slats are positioned at a sharp angle (8) with respect to the intended direction of the Rayleigh-Bernard convection current, i.e., between 0 and 90, so that the current of the RayleighBernard convection which hits them is always directed toward the mirror plane (10). The symmetry of the structure is linear and not cylindrical, which does not allow a uniform current density across the reservoir (Figure 1).

2. The width of the slats (7), their inclination (8) and their distance (9) are coordinated such that the vertical flow of Rayleigh-Bernard convection through the structure is closed at a sufficiently large temperature gradient or. when buoyancy is large enough (10) and open when buoyancy is gone. In this case, the current is directed between the slats of the structure (11). The slats are made of any thermally poorly conductive material, such as. from thermopolymers which are dimensionally stable up to 100C, and polyolefins are particularly suitable.

3. The distance between the blades (9) is smaller than the typical size of the Rayleigh-Bernard instability zone (14), which, when using water and some kW of heat exchanger power, is at most 20 cm at a slope of at least 45.

The SIPO Form P-1 slats may have a smaller slope. If the forces are smaller, the distance between them is correspondingly smaller.

4. The horizontal projection of the erected blades (13) is at least half greater than the RayleighBernard instability zone.

According to the invention, the structures described above are placed in the container according to the following rules:

5. Each storage tank shall have at least one filling structure and at least one discharge structure. The filling structure has a heat exchanger below and the fins direct the warm flow of Rayleigh-Bernard convection inwards and upwards. The discharge structure has a heat exchanger above and the blades direct the cool flow of Rayleigh-Bernard convection inward and downward.

6. In the horizontal direction, place the filling and discharge structures alternately and with linear symmetry.

7. Horizontal distances between filling and discharge structures are greater than the size of Rayleigh-Bernard instability zone but not larger than 1m.

8. To meet most of the thermal needs of a residential building, at least two different discharge structures are usually required to heat the heating system and to heat the hot water.

9. Since the heating system works with low power in energy-efficient buildings but consumes a lot of energy integrally, we place the appropriate discharge structure in the center of the tank.

10. Because the DHW heating system works with high power in shocks and consumes less or less. up to about the same amount of energy as the heating system, which makes the material flows even more pronounced, install a suitable discharge structure at the edge of the reservoir to minimize the impact on water stratification, while utilizing cold Rayleigh-Bernard convection currents at the reservoir wall to actively prevent heat loss through the wall of the tank. Therefore, such emptying structures, located adjacent to the wall, are carried out in half embodiment with a single vertical series of blades (5).

11. We must install filling structures in accordance with Rule 6 and Rule 7 among all the discharge structures, which means that in the case described above, two filling structures are installed with two half-empty discharge structures adjacent to the DHW walls and a discharge structure in the middle of the heating system. at the appropriate distance determined by the ratio of the dynamics of energy consumption and delivery to the storage tank.

Formed SIPO P-1

According to the invention, the system of lamellar structures and heat exchangers described above is mounted on a freestanding load-bearing structure according to the following rules:

12. The supporting structure is housed in a watertight bag that closes the water reservoir (16) and is made of elastic, flexible and poorly thermally conductive materials that allow creases to be made for the non-pressure construction of the reservoir, for which polyisobutylene is particularly suitable. Below, the bag is placed on a thin layer of thermal insulator, at least 60 cm thick on the side, of dimension-stable insulator pieces, some of which must have a radiation shield in the middle of the insulator in the form of an electrically conductive film to prevent losses by infrared radiation. Above is a blue bag on the water. when placing the structure on the top of the structure carrying the void exchangers.

13. The supporting structure below and above may be made of any material, and in the vertical direction only of thermally poorly conductive materials, in order not to break the temperature layering of water. They are suitable e.g. thermopolymers that are dimensionally stable in water at temperatures up to 100 “C, especially nylon.

14. Filler linear heat exchangers are attached to the supporting structure below. Above them are charge structures with a Rayleigh-Bernard convection constraint system as described in Rules 1 to 11.

15. Empty linear heat exchangers are attached to the supporting structure above. Below them are charge structures with a Rayleigh-Bernard convection constraint system as described in Rules 1 to 11.

16. Rayleigh-Bernard convection limiting blades and discharge structures are mounted on thermally poorly conductive bands or cords stable up to 100 “C, e.g. from temopolymers such as polyamides or Teflon. The slats can be made of poorly conductive panels or foil. In the use of the latter, a uniform tension of the blades and thus a straight shape is achieved by the forcing of a string in the form of a chain (16). The projections of the points of the anchorages of the slats describe the chain in the vertical plane (the mirror plane of the whole structure).

Claims (6)

PATENT APPLICATIONS A non-pressure seasonal water heat storage unit with a system for emphasizing the water temperature stratification, characterized in that a linear lamellar system of limiting Rayleigh-Bernard convection (4, 5) in the form of a lamella system (3) is above the filling heat exchanger (1) in the heat storage tank. , which focus the warm flow of Rayleigh-Bernard convection inwards and upwards (10) and, by analogy below the void heat exchanger (2) in the heat storage, the lamellar lines are a system of limiting Rayleigh-Bernard convection in the form of a system of lenses that focus the cold current of Rayleigh-Bernard convection inward and downward. 2. The system of claim 1, characterized in that the fins (3) of the Rayleigh-Bernard convection limiting system are arranged at an acute angle (7) with respect to the intended direction of the Rayleigh-Bernard convection current, ie between 0 and 90 "such that the Rayleigh current -Bernard's convection, which hits them, is always directed towards the mirror plane (4) and the lamellae, viewed from the side, overlap at least minimally (12). 3. The system of claims 1 and 2, characterized in that the blades are positioned linearly in a horizontal direction parallel to the heat exchanger (1) or (2) above or below which they are positioned, and that the blades are positioned in two in the full lamella system mirror symmetry groups with mirror symmetry across the plane between the two groups (4). The system of claims 1, 2, and 3, characterized in that, when the structure is placed against the wall of the reservoir, the lamellae form only one group of parallel lamellae, that is, a half-lamella structure (5). 5. The system of claims 1 to 4, characterized in that It is appreciated by SIPD P-1 that in the case of foil lamellae, the projections of the lampholder anchorages on the mirror vertical plane of the structure to constrain Rayleigh-Bernard convection represent the shape of a chain (15). 6. The system of claims 1 to 5, characterized in that it can be placed in a watertight flexible flexible storage bag, which allows non-pressure execution due to the use of the flexible bag folds (16), despite the water being stretched due to heating (17).