The subject of the invention is a stratified storage tank, useful in particular in roof solar thermal systems.

WO 02/39028 Al discloses a stratified storage tank that is designed to store working fluid at different temperatures. The tank has an internal distribution pipe with holes at different heights. The holes are intended to transfer fluid from the distribution pipe to the storage compartment of the tank. Fluid is stored in layers at various temperatures due to different density at varying temperatures. Inside the distribution pipe, there is a damping element in form of a reel, which consists of two parts: the first part tapering conically upwards and the second part tapering conically downwards. Between those parts, the body of the damping element in the shape of a reel has its maximum transversal section in its central part. The damping element is intended to decrease the linear speed of the fluid flowing through the inlet connector pipe of the tank to the distribution pipe.

The length of the damping element in line with WO 02/39028 Al makes it possible to use the solution in small systems powered with several or over a dozen solar collectors with thermal input of up to a dozen kW, which are facilitated with stratified tanks, wherein the diameter of fluid distribution pipes is small, maximally up to 50 mm. In the case of large systems, wherein the diameter of fluid distributing pipes in the stratified tank may be over 100mm, the solution described in WO 02/39028 Al does not apply, since the length of the damping element in the form of a reel would need to be over 500mm and would prevent stratified inflow of fluid within that section in the upper part of the tank. The aim of the invention is to design a solution of a stratified storage tank in solar thermal systems for very large surface areas of high thermal input, depending on the concentration of solar radiation up to several dozen kW, and significant linear speed of flowing fluid within pipes of the hydraulic circuit, reaching up to several m/s. In order to enable stratified inflow of fluid into the tank with such high speeds of the working fluid, it is necessary to decrease even a few dozen times the linear speed of the flow between the inlet connector pipe and the distribution pipe, the diameter of which may exceed 100 mm. Such a condition is not provided by stratified storage tanks known from prior state of the art. Without a successful dispersion and reduction of fluid linear speed, turbulent mixing of the fluid will occur within a wide section, with the result of averaging the temperature of inflowing fluid and the fluid present in the tank, as well as the impossibility of stratified inflow due to existing fluid turbulence.

The invention concerns a stratified storage tank with a vertical fluid distribution pipe that distributes fluid through outlets arranged at its height, whereby the distribution pipe is connected from above with an inlet connector pipe of the fluid coming from a heat source. The diameter of the inlet connector pipe is smaller than the diameter of the distribution pipe, and there is a dispersing element between the inlet connector pipe and the distribution pipe that disperses the fluid stream. The idea of this invention is that it comprises an additional initial disperse element for initial dispersion of the fluid stream, which is located between the inlet connector pipe and the dispersing element, which initial disperse element forms a check valve. The dispersing element has the form of a set of concentric rings, whereby neighboring rings form ducts with a cross- section that expands towards the bottom of the tank, while their mutual position is determined by distance elements.

The inflowing stream of fluid is dispersed and slowed down twice - initial dispersion takes place on the additional element which is the initial disperse element, while the proper dispersion takes place on the set of rings, between which ducts are formed with an expanding cross- section. Moreover, the initial disperse element serves the role of a check valve. After forced flow of the fluid in the system is stopped, gravity flows in the opposite direction occur, which results in discharge of heat on the roof surface and other elements of the hydraulic circuit. Due to heat loss on elements of the hydraulic circuit, the best solution is to place such a valve as early as at the beginning of the circuit, which is in the heat storage tank. Such a structure efficiently - a few dozen times - decreases the linear speed of flow and, moreover, allows for limitation of the length of dispersing elements, which generally does not exceed 150 mm.

In order to achieve a more efficient dispersion of fluid, side walls of the rings form a duct with an opening angle within the range from 5° to 30°. Moreover, the advantageous influence on the level of dispersion is achieved thanks to convex upper surfaces of concentric rings.

Favorably, the tank has a supporting structure that fixes the rings inside the distribution pipe.

The distance elements may be in the form of ribs that protrude above the upper edges of rings and are fixed to the inner wall of the distribution pipe, which allows to avoid an additional supporting structure. In such execution, it is justified to implement a recess in ribs to form a pocket for the initial disperse element, which serves to determine its position inside the distribution pipe.

In the simplest option, the initial disperse element is in form of a ball. In another embodiment, the initial disperse element is mushroom- shaped, and fixed on the side of the dispersing element with a mounting pin and expanded with a spring element.

The invention has been further presented in the examples shown below and in the attached drawing, in which Fig. 1 schematically presents a stratified storage tank in longitudinal section, Fig. 2 - a schematic longitudinal section through the transition of the inlet connector pipe into the distribution pipe with a visible dispersing element in the first embodiment, Fig. 3 - the dispersing element from Fig. 2 in a schematic perspective view, Fig. 4 - a schematic longitudinal section through the transition of the inlet connector pipe into the distribution pipe with a visible dispersing element in another embodiment, Fig. 5 - the dispersing element from Fig. 4 in a schematic perspective view, while Fig. 6 shows a schematic longitudinal section through the transition of the inlet connector pipe into the distribution pipe with a visible dispersing element in further embodiment.

Fig. 1 presents schematically a stratified storage tank 1 with an inlet connector pipe 2 mounted from above for fluid coming from a heat source connected with a vertical distribution pipe 3 that has outlets 4 arranged at its height. The diameter of the inlet connector pipe 2 is smaller than the diameter of the distribution pipe 3. There are a dispersing element 5 and an initial disperse element 6 located between the inlet connector pipe 2 and the distribution pipe 3, which disperse the fluid stream. In particular the initial disperse element 6 is located between the inlet connector pipe 2 and the dispersing element 5. It is obvious that the stratified storage tank 1 connected in a closed working fluid circuit of the solar thermal system is also facilitated with an outlet connector pipe that has not been presented in Fig. 1. The initial disperse element 6 forms, at the same time, a check valve that closes the flow from the inlet connector pipe 2 to the distribution pipe 3 in case of lack of fluid flow in the system.

Fig. 2 schematically shows the dispersing element 5 and the initial disperse element 6 of the fluid stream in a longitudinal section. The dispersing element 5 is in the form of a set of concentric rings 5A. In this embodiment five concentric rings were used with a central support placed inside the smallest ring. There are, however, possible embodiments without a central support. The upper surfaces of concentric rings 5A are convex, most favorably rounded. The side walls of rings 5A form ducts 5B with a cross-section that expands in the direction of the bottom of the stratified liquid tank 1, with an opening angle a within the range from 5° to 30°. In particular, the opening angle a is 10°. The mutual position of rings 5A is determined with a distance elements and, in particular in this embodiment, they are in the form of ribs 5C protruding above the upper edges of rings 5A and are fixed to the inner wall of the distribution pipe 3. In ribs 5C there is recess 8 that forms a pocket for the initial disperse element 6 of the fluid stream, which in this embodiment has the form of a ball 6A. It may be a floating rubber ball serving as a check valve closing the hydraulic circuit in the case of lack of flow. Fig. 3 presents a perspective view of the dispersing element 5, with visible rings 5A, ducts 5B located between the rings 5A ribs 5C connecting rings 5A, and recess 8 formed in the ribs 5C for the initial disperse element 6 of the fluid stream.

In another embodiment, presented in Fig. 4 and Fig. 5, the configuration of rings 5A with ducts 5B formed between them and ribs 5C that connect them is similar. The difference between this embodiment and the embodiment shown in Fig. 2 and Fig. 3 is that the initial disperse element 6 of the fluid stream is mushroom- shaped 6B and is fixed on the side of dispersing element 5 on a mounting pin 6C in a central support 6E and expanded by a spring element 6D. In that embodiment, fixing of the dispersing element 5 to the inner wall of the distribution pipe 3 also takes place thanks to ribs 5C protruding above the upper edges of rings 5A.

In another embodiment, which has been presented in a schematic way in Fig. 6, fixing of the dispersing element 5 inside the distribution pipe 3 is implemented with the use of an additional supporting structure 7, especially in the form of a protrusion or protrusions on the inner wall of the distribution pipe 3.

With reference to the above embodiments, a stratified storage tank 1 has the capacity of V>3m ³ , for example V=5m ³ and is intended for solar thermal systems with a thermal input of up to several dozen kW. The best solution for such large tanks is to place them outside the building, in the ground. In such cases, connections in the form of connector pipes are located, due to the manner of assembly, in the upper part of the tank. Application of the initial disperse element 6 for initial dispersion of the fluid stream and the dispersing element 5 with specified structures shall efficiently decrease the linear speed of flow of the fluid from the inlet connection pipe 2 to the stratified storage tank 1 through the distribution pipe 3 and, consequently, allows for stratified inflow of fluid at assumed temperature parameters. For example, in case of a diameter of inlet connector pipe 2 amounting to 20 mm and a diameter of the distribution pipe 3 equal to 120 mm, it is possible to decrease the linear speed by forty times, from about 2 m/s to about 0.05 m/s.