HK1169701B - Apparatus for heating service water - Google Patents

Description

Device for heating service water

Technical Field

The invention relates to a device for heating service water with a solar collector, comprising a service water tank with a partly cylindrical jacket as an absorber and an enclosure covering the service water tank and forming a light-transmitting cylindrical jacket, the axis of the enclosure extending parallel to the axis of the jacket of the service water tank.

Background

If service water is to be heated with the aid of solar energy, use is usually made of solar collectors which comprise a trough-shaped frame with a base plate serving as an absorber, on which parallel tubular flow channels are provided for the water, for example as a heat carrier. The tank with the absorber plates and the flow channels connected to the distribution and collection lines is provided with a light-transmitting cover, so that in particular the thermal radiation is absorbed by the absorber plates and the flow channels arranged thereon, and the absorbed heat is transferred to the heat carrier, with the aid of which the service water storage tank is filled via the heat exchanger. A disadvantage of such solar collectors is the need for a corresponding orientation with respect to the solar radiation and the need for a hot water storage tank for heating the service water, which hot water storage tank is connected to the solar collector via a heat exchanger.

In order to avoid these drawbacks, it has been proposed (DE 202006015934U 1) to use the jacket of a cylindrical service water tank as an absorber and to provide the service water tank for this purpose with an enclosure, the light-transmitting jacket of which forms a semi-cylindrical shape with an axis parallel to the axis of the tank. If the axis of the tank or enclosure is aligned approximately in the north-south direction, the cylindrical shape of the service water tank in cooperation with the enclosure forming the jacket in the form of a semi-cylinder causes substantial independence of the device from the angle of incidence of sunlight, so that substantially radial light incidence into the enclosure is ensured. Due to the temperature-dependent density of the service water, hot service water accumulates in the upper region of the horizontally arranged service water tank and can be drawn off via the upper hot water pipe by simultaneously supplying cold water in the base region. In order to reduce heat losses, the jacket of the enclosure is covered on the inside with a light-transmitting knitted fabric in order to reduce the heat radiation to the outside in the case of low outdoor temperatures. Furthermore, efforts are made to better utilize the light entering the enclosure by means of the light-reflecting bottom part. However, despite these measures, the efficiency is still limited.

Disclosure of Invention

The object of the invention is therefore based on increasing the efficiency of a solar collector in which the jacket of the service water tank is used as an absorber.

Based on a device for heating service water of the above-mentioned kind, the invention achieves this object by: the service water tank is connected in a heat-conducting manner to the absorber plate forming the bottom part of the enclosure and the absorber plate and the jacket of the service water tank are covered with a wide-mesh insulating fabric.

The provision of an additional absorber plate forming the bottom part of the enclosure and connected in a heat-conducting manner to the service water tank provides a better utilization of this heat radiation entering the enclosure, since the absorber plate heated by this heat radiation transfers the absorbed heat to the service water tank. Covering the jacket of the absorber plate and the service water tank with a wide-mesh insulating fabric prevents direct contact of the air flow formed in the enclosure by convection with the absorber plate and the service water tank, causing a higher temperature of the absorber plate and a lower cooling of the service water and thus an improved heating condition of the service water. The wide mesh of the fabric ensures a direct passage of the heat radiation through the fabric to the absorber plate and to the service water tank, wherein particularly advantageous heating conditions are obtained when the fabric itself can allow heat radiation, as is the case in glass fiber fabrics.

In order to ensure an advantageous heat transfer between the absorber plate and the service water tank, the absorber plate may house the service water tank in a cylindrical bulge located close to the jacket of the tank, thereby obtaining an enlarged heat transfer surface area. To fasten the service water tank, the service water tank can be welded to the absorber plate or welded together with the absorber plate.

This construction is particularly useful for service water tanks with a cylindrical jacket. The invention is not limited to such a cylindrical service water tank. A particularly simple constructional condition is obtained when the service water tank consists of a jacket approximately forming a semi-cylinder and a cylindrical wall connected to the inside of said jacket, the axis of which extends perpendicularly to the axis of the jacket. Since as a result of this measure the service water tank can be produced from two sheet metal cuts (cuttings) which are each cylindrically bent and then welded to one another, relatively simple production conditions can be maintained. The semi-cylindrical jacket of the service water tank, which jacket seals the cylindrical wall of the service water tank to the outside, forms, at least in the connecting region of the cylindrical wall, a projecting edge portion which represents an additional absorber surface area having a favorable effect on the heat transfer, since the semi-cylindrical jacket of the service water tank is arranged approximately coaxially with the jacket which likewise forms the semi-cylindrical enclosure, so that the thermal radiation is approximately radially aligned with respect to the jacket of the enclosure and the jacket of the service water tank, which therefore occurs approximately independently of all changes in the daytime solar position.

When the jacket of the service water tank is arranged integrally with the absorber plate, an advantageous connection of the service water tank to the absorber plate is obtained with the jacket of the service water tank in the form of a half cylinder.

Drawings

The subject matter of the invention is illustrated by way of example in the accompanying drawings, in which:

figure 1 shows a schematic cross-sectional view of a device for heating service water according to the invention;

FIG. 2 shows the apparatus in a longitudinal sectional view along line II-II of FIG. 1;

fig. 3 shows a diagram corresponding to fig. 1 of an embodiment of the apparatus for heating service water according to the invention; and

fig. 4 illustrates the apparatus of fig. 3 in a sectional view along the line IV-IV of fig. 3.

Detailed Description

According to the embodiment according to fig. 1 and 2, the device for heating service water comprises a solar collector with an enclosure 1, which enclosure 1 is composed of two semicircular face walls 2 and a jacket 3 made of light-transmitting material and forming an arch according to one half of a cylinder. The bottom part of the enclosure 1 is formed by a heat-conducting absorber plate 4, which heat-conducting absorber plate 4 is preferably made of a metal material, such as copper or aluminum, and is provided with a thermal insulation 5 on the side facing away from the jacket 3. In the region of the cylinder axis of the enclosure 1, the absorber plate 4 forms a cylindrical bulge 6 which accommodates a horizontally arranged cylindrical tank 7, the axis of the horizontally arranged cylindrical tank 7 being parallel to the axis of the enclosure 1. The arrangement is constructed by: so that the jacket 8 of the service water tank 7 rests in a planar manner on the cylindrical elevation 6 of the absorber plate 4, which thereby ensures an advantageous heat transfer from the absorber plate 4 to the tank jacket 8.

The service water tank 7 is connected at the bottom with a cold water pipe 9 and at the top with a hot water pipe 10, so that water accumulated in the upper region of the service water tank 7 can be discharged via the hot water pipe 10 while cold water is supplied into the bottom region of the service water tank 7, since the illustrated arrangement forms the service water tank within the enclosure 1 by conventional service water temperature stratification. As shown in fig. 2, in the case of switching (switch) a plurality of such apparatuses in series, each service water tank 7 is provided with a cold water pipe 9 and a hot water pipe 10 on the opposite surface sides to each other. This series connection allows temperature compensation of the service water tanks 7, which is particularly important when erecting the devices at different height levels. When the device is used alone, the ducts 9 and 10 can be sealed or omitted on one side.

Since the apparatus is advantageously erected in such a way that the axis of the enclosure 1 or the service water tank 7 extends approximately in the north-south direction, a substantially radial incidence of light is obtained during daytime solar radiation, so that advantageous conditions with respect to thermal radiation are provided, which apply not only to the absorber plate 4, but also to the service water tank 7. To improve these heating conditions, the absorber plate 4 and the jacket 8 of the service water tank 7 are covered with a wide-mesh insulating fabric 11, as indicated with the dash-dot lines in fig. 1. The mesh of the fabric 11 prevents air flow directly along the service water tank 7 and the absorber plate 4 due to the air cushion trapped within the mesh of the fabric. This means that the air flow caused by convection inside the enclosure 1 does not have a negative influence on the heat transfer in the area of the absorber plate 4 or the service water tank 7. With the advantageous constructional conditions obtained in particular in the case of glass fibre fabrics, the coarse mesh of the fabric 11 facilitates the passage of the thermal radiation through the fabric 11, since in this case the fabric 11 itself is permeable to the thermal radiation. The use of such a wide-mesh insulating fabric 11 additionally increases the efficiency.

The relevant difference between the embodiments according to fig. 1 and 2 on the one hand and fig. 3 and 4 on the other hand lies in the structure of the service water tank 7. Since the jacket 8 of the service water tank 7 according to fig. 1 and 2 forms a closed cylinder, the jacket 8 of the service water tank 7 according to fig. 3 and 4 is arranged in the form of a semi-cylinder extending substantially coaxially with the jacket 3 of the enclosure 1. As shown in fig. 4, in case the arrangement is constructed such that the semi-cylindrical jacket 8 of the service water tank 7 extends beyond the cylindrical wall 12 in axial direction on both sides, this semi-cylindrical jacket 8 of the service water tank 7 seals outwards the wall 12 which is open towards said jacket 8. The axis of the cylindrical wall 12 extends perpendicularly to the axis of the half-cylinder of the jacket 8.

Due to this arrangement, the light radiation entering substantially radially through the sheath 3 of the enclosure 1 also penetrates substantially radially onto the sheath 8 of the service water tank 7, providing advantageous heating conditions for the sheath 8 of the service water tank 7, which forms a relatively large absorption surface. Since the absorber plate 4 according to fig. 3 is arranged integrally with the jacket 8 of the service water tank 7, an advantageous heat transfer from the absorber plate 4 to the jacket 8 of the service water tank 7 is ensured. As in the embodiment according to fig. 1 and 2, the absorber plate 4 and the jacket 8 of the service water tank 7 are covered with a wide-meshed heat insulation fabric 11, preferably with a glass fiber fabric, in order to prevent as far as possible any heat loss through heat dissipation to the intermediate space between the service water tank 7 and the enclosure 1.

Claims (5)

1. A device for heating service water with solar collectors, comprising a service water tank (7) and an enclosure (1), the service water tank (7) having a closed cylindrical or semi-cylindrical jacket (8) as an absorber, the enclosure (1) covering the service water tank (7) and forming a light-transmitting, partially cylindrical jacket (3), the axis of the jacket (3) extending parallel to the axis of the jacket (8) of the service water tank (7), characterized in that the service water tank (7) is connected in a heat-conducting manner to an absorber plate (4) forming a bottom part of the enclosure (1), and the absorber plate (4) and the jacket (8) of the service water tank (7) are covered with an insulating fabric (11), wherein the insulating fabric is made as a mesh so as to facilitate heat radiation through the fabric.

2. The device according to claim 1, characterized in that the fabric (11) is made of a glass fiber fabric.

3. The apparatus according to claim 1 or 2, characterized in that the absorber plate (4) accommodates the service water tank (7) in a cylindrical bulge (6) arranged close to the cylindrical jacket (8).

4. The apparatus according to claim 1 or 2, characterized in that the service water tank (7) consists of the semi-cylindrical jacket (8) and a cylindrical wall (12) connected to the inside of the semi-cylindrical jacket (8), and the axis of the cylindrical wall (12) extends perpendicular to the jacket axis.

5. An apparatus according to claim 4, characterized in that the jacket (8) of the service water tank (7) is arranged integrally with the absorber plate (4).