LIQUID RESERVOIR

Abstract

 A liquid reservoir with a liquid inlet, a liquid outlet and an internal space defined by a housing, which comprises stored liquid and a thermal energy source, characterized in that the internal space is surrounded by at least one interspace, wherein each interspace is defined by two housings spaced apart from each other and connected by means of at least one connecting element for liquid flow with the adjacent spaces, which are the adjacent interspaces or the adjacent internal space, wherein the liquid inlet is connected to the external interspace, while the internal space of the reservoir is provided with the liquid outlet.

Description

Field of the Invention

[0001] The present invention relates to an arrangement of a reservoir system for liquid having a temperature different from the ambient temperature, provided with an internal storage space for liquid, at least one interspace, a source of thermal energy, a liquid inlet and a liquid outlet.

State of the Art

[0002] Conventional reservoirs for heated liquids, i.e. liquids with higher temperature than the ambient temperature, especially domestic hot water generators, are designed as a single-space vessel, provided with insulation layer on its external surface to reduce the amount of thermal energy being transferred from the environment with higher temperature into the environment with lower temperature, according to the first thermodynamic law.

[0003] The conventional heated liquid reservoirs are provided with external thermal insulation, usually consisting of fibrous or foam material having thickness from 6 to 12 cm, showing significant resistance towards heat transfer and serving as a means against water condensation on the surface of a storage vessel when filling the reservoir with cold water. However, the said thermal insulation does not stop but only reduces the heat transfer from the vessel with heated liquid to colder surrounding environment. In heated liquid reservoirs known in the state of the art, which usually employ free convections, the effect of thermal layering along the height of the vessel occurs. Despite insulation, thermal losses do not prevent substantially fast reduction of temperature in the hot water reservoir without energy supply. The greater the difference between the heated water reservoir temperature and the ambient temperature, the greater the irreversible energy losses from liquid to the surrounding environment.

[0004] Thermal source for water heating is usually an electric heating spiral or optionally a gas burner, however, thermal energy may be supplied by means of any other heat-carrying medium, such as hot steam. Heating source usually provided with a control circuit maintains the desired temperature level of the stored liquid.

[0005] The object of the present invention is to propose an arrangement of reservoir for liquid having different temperature than the ambient temperature, in order to reduce thermal losses to the minimum.

Summary of the Invention

[0006] The above-mentioned object of the invention is met by an arrangement of liquid reservoir with a liquid inlet, a liquid circuit and an internal space defined by a housing, comprising the stored liquid and thermal energy supply, characterized in that the internal space is surrounded by at least one interspace, wherein each interspace is defined by two housings spaced apart from each other, and connected by means of at least one connecting element for liquid flow with the adjacent spaces, which are the adjacent interspaces or the adjacent internal space, wherein the liquid inlet is connected to the external interspace, while the liquid outlet is guided outside the internal space. Each interspace is connected by the connecting means to the adjacent interspace and the last internal interspace is connected by the connecting means with the internal space of the reservoir. The connecting means may preferably be a tube or a simple opening in the upper part of the adjacent interspace.

[0007] In a preferred embodiment, due to the effect known as layering of the heated liquid resulting from changes of density and viscosity, the liquid inlet is connected to the bottom part of the external interspace and the liquid outlet is provided in the upper part of the internal space.

[0008] It is also preferred for each connecting element to have an input in the upper part of the interspace and the output in the bottom part of the following adjacent interspace or adjacent internal space.

[0009] Advantage of the present invention is that the thermal energy passing through the housing of the internal space, which is usually expected to have losses, remains trapped in liquid in the interspaces between the housings. As the temperature of liquid in interspaces between the housings is lower than the temperature of liquid in the internal space, the thermal gradient between liquid in the external interspace and the external surroundings of the reservoir is also lower. Liquid in each interspace reduces the temperature difference between the interspace and external environment, and captures the thermal energy passing through the reservoir housing. With suitable number of reservoirs and ratio of the liquid in the interspaces, it is possible to achieve that the external housing of the reservoir will only require thermal insulation in order to reduce the condensation in case of supply of liquid with lower temperature than the dew point temperature of the surroundings. The number of interspaces depends on the temperature and volume of stored liquid. For domestic hot water reservoirs, it seems that 2 or 3 interspaces are enough. In industrial applications, multiple interspaces are required.

Brief Description of Drawings

[0010] The present invention is further illustrated by means of attached drawings, wherein:

• Fig. 1 illustrates an arrangement of the reservoir with one interspace,
• Fig. 2 illustrates an arrangement of the reservoir with multiple interspaces, and
• Fig. 3 illustrates an embodiment of the heated liquid reservoir, where the internal space is surrounded by adjacent interspace only partially, therefore a part of the internal space housing forms also the external housing of the reservoir.

Description of Exemplary Embodiments

[0011] As it is shown in the Fig. 1, the present heated liquid reservoir has an internal space 1 for liquid storage with a thermal energy source 2.The walls of the reservoir consist of two housings 3 spaced apart from each other. The housings 3 define an interspace 4 therebetween, surrounding the internal space 1, preferably from all sides. A liquid inlet 5 of the reservoir is connected to the bottom part of the interspace 4. The interspace 4 is connected to the internal space 1 of the reservoir by means of the connecting element 6. The connecting element 6 has the input in the upper part of the interspace 4 and it is terminated into the bottom part of the internal space 1 of the reservoir. The liquid outlet 7 is then provided in the upper part of the internal space 1 of the reservoir.

[0012] In this arrangement, part of thermal energy of the liquid heated in the internal space 1, which passes the housing 3, is consumed by colder liquid supplied to the interspace 4, thanks to which the temperature of liquid inside the interspace rises. Thus, not cold but already preheated liquid is supplied to the internal space 1. The temperature gradient determined by the difference between temperatures of liquid in the internal space 1 and the liquid entering the interspace 4, or the temperature of the reservoir surroundings, is thus divided to two stages and thermal energy exiting the internal space 1 is actively used for preheating of the liquid in the interspace 4. This effect may be further increased by using another, or optionally more interspaces 4, so that multistage preheating of water before entering the internal space 1 of the reservoir is performed. Outlets of liquid from the particular interspaces or the internal space 1 are preferably provided in the upper parts thereof, in order to take advantage of the water layering effect in the interspace 4 as well as in the internal space 1 for heating the liquid. The liquid supplies are preferably provided in the bottom part of the interspace 4 or the internal space 1 with the purpose of liquid circulation.

[0013] Exemplary embodiment of the reservoir with multistage preheating of liquid is shown in the Fig. 2. The reservoir for preheating of liquid consists of four housings 3 spaced apart, defining the internal space 1 and three interspaces 4 therebetween, connected together by means of the connecting element 7. The interspaces 4 are arranged in layers so that the internal space 1 is surrounded by exactly one interspace 4 and this first interspace 4 is surrounded by the second interspace 4, etc. so that each next interspace 4 surrounds the previous interspaces 4 and the internal space 1.

[0014] The Fig. 3 shows an exemplary embodiment of the heated liquid reservoir, where the internal space 1 is only partially surrounded by the adjacent interspace 4, thus part of the housing 3 of the internal space 1 is also the external housing 3 of the reservoir. This arrangement may be preferably used for reducing the production costs.

[0015] With increasing number of housings 3, the temperature gradient between the particular interspaces 4 or between the external environment and the interspace 4 or the internal space 1 decreases. Finally, the amount of thermal energy leaking as loss energy into the surrounding environment is determined by the difference between temperature of the external interspace 4, the temperature of surroundings and quality of thermal insulation. In case the hot water reservoir is placed in an environment with temperature higher than the temperature of the supplied water, no thermal losses occur, only thermal gains. However, it is apparent that the higher the number of interspaces, the greater the production costs, and their number is thus limited by a suitable compromise between the amount of acceptable heat losses and the economic effectivity of production.

[0016] The above-described assembly functions as follows:

To the interspaces filled with liquid, cold liquid is forcibly supplied from the liquid inlet 5 (not shown) to the external interspace 4. The heated liquid is drained from the internal space 1 of the reservoir for usage and the drained liquid is being constantly replaced via the connecting element 6 with liquid from the adjacent interspace 4, into which colder liquid is optionally supplied from the next external interspace 4. Heat passing each housing 3 is captured in the liquid of the next interspace 4 and thus heats up the liquid.

Industrial Applicability

[0017] The present invention is intended for use in liquid systems for storage tanks, for domestic or industrial preparation of hot utility water.

List of Reference Signs

[0018] 

1

Internal space

2

Thermal energy supply

3

Housing

4

Interspace

5

Liquid inlet

6

Connecting element

7

Liquid circuit

Annotation

[0019] A liquid reservoir with a liquid inlet, a liquid outlet and an internal space defined by a housing, which comprises stored liquid and a thermal energy source, characterized in that the internal space is surrounded by at least one interspace, wherein each interspace is defined by two housings spaced apart from each other and connected by means of at least one connecting element for liquid flow with the adjacent spaces, which are the adjacent interspaces or the adjacent internal space, wherein the liquid inlet is connected to the external interspace, while the internal space of the reservoir is provided with the liquid outlet.

Claims

1. A liquid reservoir with a liquid inlet, a liquid outlet and an internal space defined by a housing, which comprises stored liquid and a thermal energy source, characterized in that the internal space (1) is surrounded by at least one interspace (4), wherein each interspace (4) is defined by two housings (3) spaced apart from each other and connected by means of at least one connecting element (6) for liquid flow with the adjacent spaces, which are the adjacent interspaces (4) or the adjacent internal space (1), wherein the liquid inlet (5) is connected to the external interspace (4), while the internal space (1) is provided with the liquid outlet (7).

2. The liquid reservoir according to claim 1, characterized in that the liquid inlet (5) is connected to the bottom part of the external interspace (4) and the liquid outlet (7) is provided in the upper part of the internal space (1).

3. The liquid reservoir according to claim 1 or 2, characterized in that the connecting element (6) has the input in the upper part of the interspace (4) and the output in the bottom part of the adjacent interspace (4) or the adjacent internal space (1).

Drawing