DE20003852U1 - Heat accumulator with integrated changeover valve for temperature-oriented feeding of liquid - Google Patents

Description

Utility model application

Applicant : Consolar Energy Storage and Control Systems GmbH

Inventors : Dipl.-Ing. Andreas Siegemund, Dr. rer. nah Rolf Meißner, Dr.-Ing. Ulrich Leibfried

Title : Heat storage tank with integrated changeover valve for temperature-oriented feed

of liquid

Description :

The invention relates to heat storage units in which heat energy can be stored and removed by forming a thermal stratification in a liquid storage medium, possibly combined with other storage media such as solids or substances with phase changes. Such storage units are used in particular as heating buffer storage units, as domestic water storage units or as combined heating buffer and domestic water storage units (so-called combination storage units).

For the sake of clarity, water is always referred to as the heat transfer and storage medium in the following, but other liquids are also possible according to the invention.

In stratified storage tanks, a temperature stratification that decreases from top to bottom is created during loading and unloading. Heated water is fed into the storage tank at the point that corresponds to its temperature and removed at the point that corresponds to the temperature that is required.

In combination storage tanks connected to a solar system, for example, there are three temperature ranges:

The uppermost area of the storage volume with the highest temperature is available for domestic water heating via a heat exchanger. Depending on the heat exchanger and the required output, a temperature of at least 55 ⁰ C is required here.

Heating energy is taken from the middle storage area below at temperatures that depend on the connected heating system and the required heating output, e.g. between 35 and 45 ^° C.

The middle and upper storage areas of solar combination storage tanks can be heated with solar energy or with a conventional heat source, such as a boiler. This ensures that the heat supply for hot water and heating is guaranteed in all weather conditions.

The lower storage area is only heated by the solar system and is only heated when the feed temperatures of the solar circuit are too low for the middle and upper solar energy areas.

Different techniques are known for feeding the various water inlets of the reservoir to the right place: .

External switching valves :

A generally known and implemented option for temperature-oriented water supply is to guide the water through one or more external switching valves that lead to storage connections at different heights. There are such arrangements with electrically operated valves, the control then requires electronic control with temperature sensors. The effort for this is comparatively large. Alternatively, there are also switching valves with a passive function: expansion elements that switch the valve at a certain temperature.

The disadvantage of both arrangements is the increased piping and insulation effort outside the storage tank and the increased heat losses through the pipes and fittings.

Internal control systems with flaps:

One way of implementing temperature-oriented water supply internally in the storage tank is to use guide pipes that extend inside the storage tank over the height within which water of different temperatures is to be fed in. The guide pipes are equipped with one or more easily movable flaps that open or remain closed depending on the density difference between the water inside and outside. One such device is described in DE 39 05 874. Such check valves have the disadvantage that they are delicate and therefore susceptible to failure, particularly due to contamination and/or calcification, since the closing pressures are minimal. Maintenance - if it is possible at all - is very complex.

Internal open control systems :

There are a number of documents describing open guide systems. These are generally tubular structures that extend within the reservoir over the height within which water of different temperatures is to be fed in. For this purpose, the guide systems have openings, some of which are designed to prevent the water from escaping at the wrong place or to prevent still water from being sucked in by means of various flow chicanes. Internal open guide systems are described in the following documents, among others: DE 197 03 724, DE 195 16 837, DE 197 43 503, EP 92109944:0 and DE 197 04 914. The device described in DE 30 44 079 ■ represents a combination of an open guide system and an internal guide system with flaps.

Our own investigations into such devices have shown that they do not work reliably. The correct temperature stratification only works - if at all - at a certain flow rate. At all other flow rates, the water either comes out of the guide tube at the wrong point to the openings or water from the storage tank is sucked into the guide tube and mixed.

Internal passively moving feed pipes :

Another method for temperature-adjusted water supply is flexible pipes inside the water, the outlet of which leads into a small container with an opening, which, due to the density of the water in the container, is at the height with the corresponding temperature in the water.

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The water comes out through the opening. Realized example: Medusa by BODEWA, I-39040 Freienfeld.

The disadvantage of these devices is their susceptibility to failure: the flexibility of the hose (made of an ■ elastomer) can be lost over time in hot water, sludge (from heating water and/or lime) can settle on the hose and container and thus change the set weight so that the feed no longer occurs at the right place. A large and therefore expensive maintenance opening is required for maintenance.

Internal actively moving feed pipes :

Feed pipes that can be swiveled within the tank by a servomotor are also used for temperature-adjusted feed. Realized example: "Multifunctional tank" from HEHT, D - 08606 Taltitz. The disadvantage of this arrangement is the effort and potential risk of failure of the movable feed-through through the tank as well as the effort for the servomotor, temperature sensor and electronic control.

Another implementation was presented in 1999 by the company Ikarus, D-87437 Kempten: here, two concentric plastic pipes with row bores are installed inside the tank. The inner pipe is firmly connected to the connection piece on the tank floor and is provided with a vertically arranged row bore. The row bore of the slipped-over, freely rotating outer pipe is spiral-shaped. A defined opening is created at the intersection point of the vertical and spiral bore arrangement. The outlet height for the supplied water can thus be adjusted using a servomotor. This arrangement is also comparatively complex, both in terms of production and control.

The invention is intended to provide a solution with which water can be layered into at least two different areas of different heights of a storage tank depending on the temperature. The device is to be integrated into the storage tank in order to avoid external piping, penetrations through the insulation of the storage tank and heat losses. It is to be self-regulating, i.e. it is to require no electronic control with temperature sensors. It is to function reliably and safely at a wide range of flow rates and is easy to maintain. The device is to be cost-effective to implement.

The task described above is solved as follows:

At least one automatic valve with a thermal expansion element is installed in the storage tank. The valve is located inside the storage tank in a housing with at least two outlets that lead to the desired areas. The valve can be removed and installed through a small opening in the storage tank, which can be closed with a screw connection, for example. The invention can be implemented cost-effectively by using thermostat valves, which are used in very large quantities in the automotive engine sector.

Figure 1 shows an embodiment of the invention. The liquid storage medium (2) is located in the storage container (1) (shown reduced in size in the figure). The housing (3) for the valve insert (4) is installed on the inside of the container (1). The valve insert is accessible from the outside through the inspection opening with

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Closure (5) can be installed and removed. The supply line (1) leads into the housing (3). The supplied water flows around the expansion body (6), which pushes out the pin (7) more or less depending on the temperature. This moves the expansion body together with its valve surfaces (9) in such a way that either the lower outlet pipe (8) for colder water or the upper outlet pipe (9) for warmer water is opened and the other is closed.

Claims (6)

1. Heat storage device in which heat energy can be layered in a liquid storage medium in a temperature-dependent manner in at least two different areas of different heights of a storage device, whereby a thermal stratification is formed, characterized in that at least one automatic valve with a thermal expansion element (6) is mounted on the storage container (1) in a housing (3) with at least two outlets (8, 9) which lead into the desired areas. 2. Heat storage device according to claim 1, characterized in that the housing (3) is located inside the storage container (1). 3. Heat storage device according to claim 1, characterized in that the housing (3) is located in the wall of the storage container (1). 4. Heat accumulator according to claim 1, characterized in that the housing is located on the outside of the container wall. 5. Heat accumulator according to claims 1-4, characterized in that the valve can be removed and installed through a small opening on the housing (3), which can be closed, for example, with a screw socket. 6. Heat storage device according to claims 1-5, characterized in that thermostat valves from the automotive engine sector are used.