What Is Passive Solar?

A passive solar water heater includes a heat collecting shell with a transparent cover, a reflective surface, and two end walls. The built-in water storage tank can be heated by direct sunlight and reflected light from the inner surface of the heat collecting shell. The water storage tank has a cylindrical peripheral wall and two end walls, and the two tubes extend along the longitudinal axis of the water storage tank, pass through and are attached to the two end walls of the water tank, and extend in the water storage tank toward the cylinder The first position and the second position of the peripheral wall, the first two positions are generally opposite to each other, and the two pipes extend through the two walls of the heat collecting shell to support the water storage tank in the heat collecting shell. The relative position between the heat collecting shell, the water storage tank and the bracket can be adjusted as required.

Solar water heater heat exchangers use the energy absorbed from the sun to heat water. They are a very effective way to heat water because they do not use non-renewable resources and the sun costs nothing. Solar water heater heat exchangers are divided into active and passive Two types.

Because of its economical use, solar water heating systems have entered commercial use. Therefore, more research and development work has been performed in this field. A significant tendency is to focus on simplifying its structure, reducing manufacturing costs, making it easy to install and less prone to failure of moving parts. Passive circulation relies on gravity to operate, and no circulating water pump is needed. Because there is no electronic control equipment, passive solar water heaters are more reliable and the cost is relatively low. The disadvantage of the passive system is the slow response. In addition, the water tank must be installed above the collector.

The most familiar non-mechanical solar water heating system, the principle of this system is to use the well-known siphon effect to introduce a solar collector into an insulated water storage tank installed above the collector. However, there is a more simplified device than a thermosiphon system, which is a passive solar water heater, or a suffocating solar collector, which can also be called an integrated heat collection / storage system (ICS). The important difference between the two is that in a passive system, the heat collection surface is also the surface of the water tank, so the heat collection and water storage can be integrated into one, and the materials used can save much more than a thermosiphon system. This passive system essentially forms a solar heating expansion tube in the cold water introduction tube leading to the hot water system. Therefore, for its installation height relative to the building or water source, it is only necessary to consider whether the on-site water pressure is sufficient to allow water to flow through the solar water heater to the place where hot water is needed.

Passive solar water heaters include a collector housing with a transparent flat surface on the inside, a curved reflecting surface and two end walls; a water storage tank is installed in the collector, and its position can be just received by the collector. The sunlight reflected on the surface is heated and has a cylindrical outer wall. Its curved surface can reflect sunlight from various angles to the water tank and the opposite end wall; there is a first pipe passing along the longitudinal axis of the water tank and attached to One end wall extends to the first position near the cylindrical tank wall in the storage tank; the second pipe passes along the longitudinal axis of the storage tank and is attached to the other

figure 1

The end wall on one side extends to the second position in the storage tank near the wall of the cylindrical tank; the first and second positions described above are generally in opposite directions in the radial direction; the first and second pipes are outward Extending through the two end walls of the collector housing, this supports the collector housing and the sample storage in a detachable structure to support the water storage tank in the collector housing; the collector housing in a detachable structure Assemble with the water storage tank at the required relative position.

The aspects of the invention (only as examples) are shown in the drawings as follows:

FIG. 1 is a general view of the passive solar water heater of the present invention;

Figure 2 is an end view of the water heater shown in Figure 1;

3 is a sectional view of a water storage tank to which the solar hot water system shown in FIG. 1 is applied;

4 is a sectional view taken along line 4-4 in FIG. 3;

5 is a detailed view taken along line 5-5 in FIG. 1;

FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. 1.

Each figure shows a passive solar water heater. As shown in Figures 1 and 2, it includes

figure 2

Contains a collector housing 2, with a flat bottom portion 3, a transparent upper cover 41, a curved reflective inner surface 6, and two end walls 8. Note that the collector housing can be seen from Figures 2, 5, and 6 It is preferably composed of a thermally insulating material 10 and preferably is a foam-type synthetic resin 1 such as polyurethane, and has a reflective inner surface 6 and an outer skin 12.

A water storage tank 14 is located in the heat collector casing 2 and its position can be heated by the sunlight reflected by the inner surface 6 of the heat collector casing 2. The water tank 14 has a circular arrow-shaped tank wall 16 and an opposite end wall 18S. The water storage tank 14 is shown in detail in FIG. 3.

The first pipe 20 extends through 22 and is mounted on one end wall 18-particularly shown in Figs. 3 and 6; the first pipe 20 extends along the longitudinal axis of the water storage tank 14 and then extends to the first position 24; This is the part of the water storage tank 14 near the cylindrical wall 16. At the other end of the water heater, there is a second pipe 26 extending into and installed on the other end wall 18 which is also along the longitudinal axis of the water storage tank 14

image 3

The line extends inside the water tank to a second position 28 near the rounded wall 16. The above-mentioned first and second two positions 24 and 28 are substantially opposite in the radial direction 1. See FIGS. 2 and 3.

The storage box 14 is provided with an internal reinforcement frame 30 to support the pipes 20 and 26; the reinforcement frame 30 is welded to each other at 32, to the storage tank at 34, and to the pipe at 36. An opening 38 is made in the reinforcement frame 30 to receive the first and second pipes 20 and 26.

As shown in FIG. 6 in particular, 3 should be made with a symbol 40 on the protruding portions of the pipes 20 and 26 to indicate the direction in which the pipe is bent in the storage tank, because the internal conditions of the storage tank are invisible from the outside.

The above arrangement of the tubes 20 and 26 and the reinforcement frame 30 ensures that the water storage tank 14 is supported by the tubes 20 and 26 in the heat collector housing.

As shown in FIG. 1 and FIG. 2, the heater has a bracket, which includes a pair of longitudinal members 42, and a pair of legs 44 at each end, which extend upward and meet at 46 to meet. Laterally there are braces 48 for reinforcement. As shown in Figure 2, there are several positioning maps 50, which can be

Figure 4 Figure 5

Sliding on the legs, so that the collector housing 2 can easily change its angle to the sun without causing the water tank to shift from its preferred position. How to use the positioning ring 50 to fix the housing 2 can be used. Well-known methods in pipe technology.

The water storage tank 14 is fixedly connected to the pipes 20 and 26 by a pipe connection to fix its rotational position.

The entire heater uses a detachable device to fix the relative position between the collector housing 2 and the water storage tank 14 and the relative position of the two with the ground or the mounting surface. As shown in FIG. 6, each set of fixing devices includes a set screw 52 that is screwed into a wire hole 54 on the connecting head 46 of the leg 44. Tighten the positioning wire 52 to compress the center sleeve of the bracket to the tube, as shown in Figure 6. The sleeve 46 is equipped with a bushing 56 made of rubber or neoprene at the joint 46, and the sleeve 58 is aluminum. The bushing 56 provides a good frictional fit to the tubes 20 and 26, and can prevent heat from being transmitted from the tubes 20 and 26 to the bracket 44 and lose heat. For the same purpose, where the tubes 20 and 26 extend through the collector housing 2, a gasket 60 is added, and a groove 62 is formed on the outer edge of the gasket to fit the flange prepared on the outer skin 12 of the collector housing 2. 64 phases mesh.

As shown in Figure 5, the collector housing 2 has a glass cover 4, which is clamped in a ferrule 66. This ferrule is mounted in a 68

Image 6

On the collector housing 2, the installation between the glass cover and the ferrule must also be sealed with a gasket 70. Figure 5 shows a better specific design, which can be seen under the glass cover Two layers of plastic film 72 (preferably polytetrafluoroethylene) are flattened with splines 74, so that a three-layer system is formed, and two layers of air cushions are formed in the middle to provide better thermal insulation. Such a system is particularly needed for heat storage in colder climates.

The operation of this water heater is extremely simple. First loosen the positioning ring 50 on the bracket, and adjust the collector housing to the required angle. Then loosen the screw 52 to rotate the water storage tank 14 and the pipes 20 and 26 until the symbol 40 outside the pipe indicates that the cold water inlet of the pipe 26 is already at the lowest point in the water tank and the hot water outlet of the pipe 20 is in the water tank. The highest point. To the pipes 20 and 26, the necessary water pipes can be connected by ordinary screw joints, respectively. In this way, the water storage tank 14 can be adjusted to the required angular position, so that the flow of heat and exhaust gas are optimal. Cold water flows through the heater and is directly illuminated by sunlight, and the sunlight is focused on the water storage tank 14 by the reflecting surface The water was quickly heated.

An important feature of a passive solar water heater is the support structure of its water storage tank. The design described above enables both the collector housing 2 and the water storage tank 14 to rotate independently of each other without affecting the connection of the water pipes. This is because each component has a common rotation axis that is in line with the central axis of the water storage tank 14, even when it is rotated, the collector housing 2 and the water storage tank 14 can be maintained symmetrically in the heater and they are in the tube. The mounting design on 20 and 26 ensures that no interference occurs between the structure and the bracket. The reinforcement frame 30 in the water tank I4 ensures that the heater has sufficient strength to support itself. In order to work effectively, the turning portions of the pipes 20 and 26 must always be in the vertical direction. This makes the pipes 20 and 26 regardless of the collector shell. The design that the body 2 can keep vertical at any angular position is simple in this invention. The positions of the water inlet and the water outlet can also be easily reversed, that is, the water storage tank 14 is rotated by 180 degrees. The water storage tank 14 can also use the siphon effect of the water inlet pipe to drain the stored water. The shape of the collector housing makes it suitable for the position adjustment. All light that is irradiated or passed through will be focused on the water tank and shot hard.

It can be seen that the angular position of the water storage tank and the angular position of the collector shell of the solar water heater provided by this invention are independent of each other, and both are independent of the installation under the legs The slope angle of the face. This design makes it possible to adjust the water storage tank to the ideal position of the exhaust and water inlet regardless of the tilt angle of the collector housing and whether it is installed on a flat surface or on an inclined surface.

The collector housing can be kept in one position all year round, or it can be adjusted according to the season or need to increase the amount of sunlight without adjusting the position of the water tank, and it is not necessary to remove the internal reinforcement of the inlet and outlet pipes. The water tank is installed on the water supply pipe, which avoids mutual interference with the rotation of the collector housing.

When manufacturing such a heater, care must be taken to ensure that its reflective surface is as smooth as possible and its light absorbing surface is as dark as possible, preferably black. That is to say, the inner surface 6 of the collector housing 2 must be accurately polished, and the outer surface of the water storage tank 14 must be painted with black, or better covered with a black film, which can increase a kind of heat radiation loss reduction. Characteristics The outer skin of the collector housing 2 is best to be pre-painted aluminum or galvanized steel, the legs can be made of aluminum tubes to make it lighter, and the storage tank 14 can be made of stainless steel ^[1] .

In various existing passive solar water heaters; the water tank is installed in the whole

A fixed position in the shell; the arrangement of the hot water outlet position on the water tank must be such that when the water heater faces the sun at an angle, the hot water outlet is at the highest position of the water tank in order to exhaust air to the maximum extent. If the water tank is arranged so that the opening of the hot water outlet pipe is not at the highest point of the water tank; the air trapped at the top of the water tank will increase, which will reduce the contact area between the water and the water tank, and accordingly reduce the heat transfer efficiency to water. It can be seen that this design has a problem especially for those horizontally installed water tanks, that is, it is even obvious when the inclination of the installation site is very flexible and it is appropriate to encounter different latitudes and different roof slopes. In addition, if it is necessary to adjust the inclination according to the season to increase its heat collection capacity, it is even more difficult or impossible ^[1] .